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Sample records for delayed larval development

  1. A note on the population genetic consequences of delayed larval development in insects

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    Marcos Mattoso de Salles

    2013-01-01

    Full Text Available Observations by Dobzhansky's group in the 1940s suggesting that the presence of recessive genotypes could account for lower larval developmental rates in Drosophila melanogaster were not confirmed at the time and all subsequent investigations on this subject focused on the analysis of ecological models based on competition among pre-adult individuals. However, a paper published in this journal in 1991 eventually confirmed the finding made by Dobzhansky and his co-workers. In this report, we provide a theoretical analysis of the population genetic effects of a delay in the rate of larval development produced by such a genetic mechanism.

  2. Larval development of japanese "conchostracans"

    DEFF Research Database (Denmark)

    Olesen, Jorgen; Fritsch, Martin; Grygier, Mark J.

    2013-01-01

    For comparison with the remarkable larvae of the laevicaudatan (clam shrimp) Lynceus brachyurus, a basic description of the larval sequence of another laevicaudatan branchiopod, the Japanese Lynceus biformis, is provided. Four larval stages have been identified, ranging in size from 258 to 560 mu m...... to the endopod and a change in the form of the naupliar process, used for food manipulation, from a long, unbranched, pointed spine to a bifid structure. In addition, buds of trunk limbs (five pairs) first appear externally in stage 4 but can be recognized through the cuticle in the previous stage. The larval...

  3. Estimating of larval stadia of West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) developed in the artificial larval diet by measuring larval head widths.

    OpenAIRE

    下地, 幸夫; Shimoji, Yukio; 琉球産経株式会社

    2003-01-01

    The survey conducted by measuring larval head widths of West Indian sweetpotato weevil Euscepes postfasciatus developed in the artificial larval diet revealed that there were five larval stadia in the developmental period. The result of this experiment can be used to estimate the larval stadia approximately in the artificial larval diet.

  4. Knockdown of Cs-Spook induces delayed larval molting in rice striped stem borer Chilo suppressalis.

    Science.gov (United States)

    Shahzad, Muhammad Faisal; Li, Yao; Ge, Chang; Sun, Yang; Yang, Qiupu; Li, Fei

    2015-03-01

    Spook has essential roles in the biogenesis of the molting hormone 20-hydroxyecdysone (20-E). The function of spook in the rice striped stem borer (SSB) Chilo suppressalis remains unclear, prompting our hypothesis that it exerts actions similar to those reported for other insect species. Here we amplified the full-length transcript of spook (Cs-Spook) in SSB by 5' and 3' rapid amplification of cDNA ends. Cs-Spook has conserved P450 motifs such as Helix-C, Helix-I, Helix-K, and PERF motif (PxxFxPxRF). It was highly expressed in late instar larvae but less so in newly molted larvae. Cs-Spook was highly expressed in prothoracic glands. Cs-Spook was knocked down by dsRNA treatments. Compared with controls, the gene expression level was reduced to 9% at 24 h post injection (PI), 33% at 48 h PI, and 24% at 72 h PI. The ecdysteroid titer decreased significantly in the dsRNA-treated group (P < 0.05), resulting in delayed larval development. The delayed development in dsRNA-treatment group was rescued by treating with 20-E. Our work demonstrates that Cs-Spook participates in the biogenesis of 20-E and regulates the molt of SSB, as seen in other species.

  5. Larval development and settlement of a whale barnacle.

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    Nogata, Yasuyuki; Matsumura, Kiyotaka

    2006-03-22

    Larval development and settlement of whale barnacles have not previously been described, unlike intertidal barnacles. Indeed, the mechanisms of the association between barnacles and whales have not been studied. Here we describe the larval development and settlement of the whale barnacle, Coronula diadema, and possible involvement of a cue from the host in inducing larval settlement. Eight-cell stage embryos were collected from C. diadema on a stranded humpback whale, incubated in filtered seawater for 7 days, and nauplius larvae hatched out. When fed with Chaetoceros gracilis, the nauplii developed to stage VI, and finally metamorphosed to the cypris stage. The larval development looked similar to that of intertidal barnacles with planktotrophic larval stages. The cyprids did not settle in normal seawater, but did settle in polystyrene Petri dishes when incubated in seawater with a small piece of skin tissue from the host whale. This strongly suggests the involvement of a chemical cue from the host whale tissue to induce larval settlement.

  6. Larval development of Evermannia zosterura (Perciformes: Gobiidae).

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    González-Navarro, Enrique; Saldierna-Martínez, Ricardo Javier; Aceves-Medina, Gerardo

    2014-06-01

    Gobiidae is the most specious fish family in the world with almost 2 000 species, however only 11% of them have been described for their larval stages. The entire life cycle information is essential to understand the biology and ecology of this important fish group. Previous studies on zooplankton samples from Ensenada de La Paz, México, have shown the presence of several Gobiidae larvae and juveniles which were identified as Evermania zosterura. The main objective of this work was to describe the larval stages of this species, widely distributed in the Eastern tropical Pacific. The development of E. zosterura larvae was described based on 66 specimens. A total of 53 specimens were used to describe morphometrics and pigmentation patterns, while 13 specimens were cleared and stained, to obtain meristic characteristics. Cleared specimens had 30 to 31 total vertebrae; dorsal-fin elements: IV; 1, 13-14, anal-fin elements: 1, 13-14, and most had pterygiophore formula 4-111100. The combination of these characteristics confirmed these specimens as E. zosterura. The pigment pattern is similar throughout ontogeny. Larvae are characterized by having three to five dendritic melanophores along the post-anal ventral margin, four to nine smaller melanophores along the ventral margin between the isthmus and anus, and one on the midpoint of the dorsal margin of the tail. There is one small pigment spot on the angle of the jaw, and other on the tip of lower lip. There is an elongated internal pigment under the notochord, between the head and gas bladder. Notochord flexion starts near 3.5mm BL and ends at 4.6mm BL; transformalion to the juvenile stage is at about 13.6mm BL. Our conclusion is that the most useful characters to distinguish this species early-larval stages from those of similar species in the area, are the number of myomeres, the large melanophores (approximately uniformly in size) on the post anal ventral margin, and the elongate internal pigment under the notochord

  7. Arrested larval development in cattle nematodes.

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    Armour, J; Duncan, M

    1987-06-01

    Most economically important cattle nematodes are able to arrest their larval development within the host - entering a period of dormancy or hypobiosis. Arrested larvae have a low death rate, and large numbers can accumulate in infected cattle during the grazing season. Because of this, outbreaks of disease caused by such nematodes can occur at times when recent infection with the parasites could not have occurred, for example during winter in temperature northern climates when cattle are normally housed. The capacity to arrest is a heritable trait. It is seen as an adaptation by the parasite to avoid further development to its free-living stages during times when the climate is unsuitable for free-living survival. But levels of arrestment can vary markedly in different regions, in different cattle, and under different management regimes. Climatic factors, previous conditioning, host immune status, and farm management all seem to affect arrestment levels. In this article, James Armour and Mary Duncan review the biological basis of the phenomenon, and discuss the apparently conflicting views on how it is controlled.

  8. Delayed Speech or Language Development

    Science.gov (United States)

    ... to 2-Year-Old Delayed Speech or Language Development KidsHealth > For Parents > Delayed Speech or Language Development ... child is right on schedule. Normal Speech & Language Development It's important to discuss early speech and language ...

  9. Contributions for larval development optimization of Homarus gammarus

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    Pedro Tiago Fonseca Sá

    2014-06-01

    The seawater rising temperature resulted in a decrease of intermoult period in all larval development stages and at all tested temperatures, ranging from 4.77 (Z1 to 16.5 days (Z3 at 16°C, whereas at 23°C, ranged from 3:02 (Z1 and 9.75 days (Z3. The results obtained are an extremely useful guide for future optimization of protocols on larval development of H. gammarus.

  10. Larval development of Evermannia zosterura (Perciformes: Gobiidae)

    OpenAIRE

    González-Navarro, Enrique; Saldierna-Martínez, Ricardo Javier; Aceves-Medina, Gerardo

    2013-01-01

    Gobiidae is the most specious fish family in the world with almost 2 000 species, however only 11% of them have been described for their larval stages. The entire life cycle information is essential to understand the biology and ecology of this important fish group. Previous studies on zooplankton samples from Ensenada de La Paz, México, have shown the presence of several Gobiidae larvae and juveniles which were identified as Evermania zosterura. The main objective of this work was to describ...

  11. Larval development of Brachiopod Coptothyris grayi (Davidson, 1852) (Brachiopoda, Rhynchonelliformea).

    Science.gov (United States)

    Kuzmina, T V; Temereva, E N; Malakhov, V V

    2016-11-01

    The larval development of the Brachiopod Coptothyris grayi (Davidson, 1852) from the Sea of Japan is described for the first time. Ciliated blastula proved to represent the first free-swimming stage. The blastopore is initially formed as a rounded hole stretching later along the anteroposterior axis. The larva is first divided into two lobes (the apical lobe and the trunk); the mantle lobe is formed later as two lateral folds. Two pairs of seta bundles appear in the late stage larvae. The apical larval lobe in brachiopods is supposed to match the pre-oral lobe and anterior part of the trunk with tentacles in phoronids.

  12. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

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    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-01-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

  13. Role of elongator subunit Elp3 in Drosophila melanogaster larval development and immunity

    DEFF Research Database (Denmark)

    Walker, Jane; Kwon, So Yeon; Badenhorst, Paul

    2011-01-01

    The Elongator complex has been implicated in several cellular processes, including gene expression and tRNA modification. We investigated the biological importance of the Elp3 gene in Drosophila melanogaster. Deletion of Elp3 results in larval lethality at the pupal stage. During early development......, larval growth is dramatically impaired, with progression to the third instar delayed for ~24 hr, and pupariation occurring only at day 14 after egg laying. Melanotic nodules appear after 4 days. Microarray analysis shows that stress response genes are induced and ecdysone-induced transcription factors...... are severely repressed in the mutant. Interestingly, the phenotypes of Elp3 flies are similar to those of flies lacking the domino gene, encoding a SWI/SNF-like ATP-dependent chromatin-remodeling enzyme. Indeed, the gene expression profiles of these mutants are also remarkably similar. Together, these data...

  14. Social coercion of larval development in an ant species

    Science.gov (United States)

    Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

    2016-04-01

    Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults.

  15. Development of larval motor circuits in Drosophila.

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    Kohsaka, Hiroshi; Okusawa, Satoko; Itakura, Yuki; Fushiki, Akira; Nose, Akinao

    2012-04-01

    How are functional neural circuits formed during development? Despite recent advances in our understanding of the development of individual neurons, little is known about how complex circuits are assembled to generate specific behaviors. Here, we describe the ways in which Drosophila motor circuits serve as an excellent model system to tackle this problem. We first summarize what has been learned during the past decades on the connectivity and development of component neurons, in particular motor neurons and sensory feedback neurons. We then review recent progress in our understanding of the development of the circuits as well as studies that apply optogenetics and other innovative techniques to dissect the circuit diagram. New approaches using Drosophila as a model system are now making it possible to search for developmental rules that regulate the construction of neural circuits.

  16. Inhibition of Haemonchus contortus larval development by fungal lectins.

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    Heim, Christian; Hertzberg, Hubertus; Butschi, Alex; Bleuler-Martinez, Silvia; Aebi, Markus; Deplazes, Peter; Künzler, Markus; Štefanić, Saša

    2015-08-19

    Lectins are carbohydrate-binding proteins that are involved in fundamental intra- and extracellular biological processes. They occur ubiquitously in nature and are especially abundant in plants and fungi. It has been well established that certain higher fungi produce lectins in their fruiting bodies and/or sclerotia as a part of their natural resistance against free-living fungivorous nematodes and other pests. Despite relatively high diversity of the glycan structures in nature, many of the glycans targeted by fungal lectins are conserved among organisms of the same taxon and sometimes even among different taxa. Such conservation of glycans between free-living and parasitic nematodes is providing us with a useful tool for discovery of novel chemotherapeutic and vaccine targets. In our study, a subset of fungal lectins emanating from toxicity screens on Caenorhabditis elegans was tested for their potential to inhibit larval development of Haemonchus contortus. The effect of Coprinopsis cinerea lectins - CCL2, CGL2, CGL3; Aleuria aurantia lectin - AAL; Marasmius oreades agglutinin - MOA; and Laccaria bicolor lectin - Lb-Tec2, on cultivated Haemonchus contortus larval stages was investigated using a larval development test (LDT). To validate the results of the toxicity assay and determine lectin binding capacity to the nematode digestive tract, biotinylated versions of lectins were fed to pre-infective larval stages of H. contortus and visualized by fluorescent microscopy. Lectin histochemistry on fixed adult worms was performed to investigate the presence and localisation of lectin binding sites in the disease-relevant developmental stage. Using an improved larval development test we found that four of the six tested lectins: AAL, CCL2, MOA and CGL2, exhibited a dose-dependent toxicity in LDT, as measured by the number of larvae developing to the L3 stage. In the case of AAL, CGL2 and MOA lectin, doses as low as 5 μg/ml caused >95 % inhibition of larval

  17. Development of environmental tools for anopheline larval control

    OpenAIRE

    Mweresa Collins K; Imbahale Susan S; Takken Willem; Mukabana Wolfgang R

    2011-01-01

    Abstract Background Malaria mosquitoes spend a considerable part of their life in the aquatic stage, rendering them vulnerable to interventions directed to aquatic habitats. Recent successes of mosquito larval control have been reported using environmental and biological tools. Here, we report the effects of shading by plants and biological control agents on the development and survival of anopheline and culicine mosquito larvae in man-made natural habitats in western Kenya. Trials consisted ...

  18. Food selection in larval fruit flies: dynamics and effects on larval development

    Science.gov (United States)

    Schwarz, Sebastian; Durisko, Zachary; Dukas, Reuven

    2014-01-01

    Selecting food items and attaining a nutritionally balanced diet is an important challenge for all animals including humans. We aimed to establish fruit fly larvae ( Drosophila melanogaster) as a simple yet powerful model system for examining the mechanisms of specific hunger and diet selection. In two lab experiments with artificial diets, we found that larvae deprived of either sucrose or protein later selectively fed on a diet providing the missing nutrient. When allowed to freely move between two adjacent food patches, larvae surprisingly preferred to settle on one patch containing yeast and ignored the patch providing sucrose. Moreover, when allowed to move freely between three patches, which provided either yeast only, sucrose only or a balanced mixture of yeast and sucrose, the majority of larvae settled on the yeast-plus-sucrose patch and about one third chose to feed on the yeast only food. While protein (yeast) is essential for development, we also quantified larval success on diets with or without sucrose and show that larvae develop faster on diets containing sucrose. Our data suggest that fruit fly larvae can quickly assess major nutrients in food and seek a diet providing a missing nutrient. The larvae, however, probably prefer to quickly dig into a single food substrate for enhanced protection over achieving an optimal diet.

  19. Resource Limitation, Controphic Ostracod Density and Larval Mosquito Development.

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    Raylea Rowbottom

    Full Text Available Aquatic environments can be restricted with the amount of available food resources especially with changes to both abiotic and biotic conditions. Mosquito larvae, in particular, are sensitive to changes in food resources. Resource limitation through inter-, and intra-specific competition among mosquitoes are known to affect both their development and survival. However, much less is understood about the effects of non-culicid controphic competitors (species that share the same trophic level. To address this knowledge gap, we investigated and compared mosquito larval development, survival and adult size in two experiments, one with different densities of non-culicid controphic conditions and the other with altered resource conditions. We used Aedes camptorhynchus, a salt marsh breeding mosquito and a prominent vector for Ross River virus in Australia. Aedes camptorhynchus usually has few competitors due to its halo-tolerance and distribution in salt marshes. However, sympatric ostracod micro-crustaceans often co-occur within these salt marshes and can be found in dense populations, with field evidence suggesting exploitative competition for resources. Our experiments demonstrate resource limiting conditions caused significant increases in mosquito developmental times, decreased adult survival and decreased adult size. Overall, non-culicid exploitation experiments showed little effect on larval development and survival, but similar effects on adult size. We suggest that the alterations of adult traits owing to non-culicid controphic competition has potential to extend to vector-borne disease transmission.

  20. Interactive Effects of Endogenous and Exogenous Nutrition on Larval Development for Crown-Of-Thorns Starfish

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    Ciemon Frank Caballes

    2017-03-01

    Full Text Available Outbreaks of crown-of-thorns starfish are often attributed to step-changes in larval survivorship following anomalous increases in nutrients and food availability. However, larval growth and development is also influenced by the nutritional condition of spawning females, such that maternal provisioning may offset limitations imposed by limited access to exogenous sources of nutrients during the formative stages of larval development. This study examined the individual, additive, and interactive effects of endogenous (maternal diet: Acropora, Porites, mixed, and starved and exogenous (larval diet: high concentration at 104 cells·mL−1, low concentration at 103 algal cells·mL−1, and starved nutrition on the survival, growth, morphology, and development of larvae of the crown-of-thorns starfish. Female starfish on Acropora and mixed diet produced bigger oocytes compared to Porites-fed and starved treatments. Using oocyte size as a proxy for maternal provisioning, endogenous reserves in the oocyte had a strong influence on initial larval survival and development. This suggests that maternal reserves can delay the onset of obligate exogenous food acquisition and allow larvae to endure prolonged periods of poor environmental nutritive conditions or starvation. The influence of exogenous nutrition became more prominent in later stages, whereby none of the starved larvae reached the mid-to-late brachiolaria stage 16 days after the onset of the ability to feed. There was no significant difference in the survival, development, and competency of larvae between high and low food treatments. Under low algal food conditions, larvae compensate by increasing the length of ciliated feeding bands in relation to the maximum length and width, which improve food capture and feeding efficiency. However, the effects of endogenous nutrition persisted in the later developmental stages, as larvae from starved females were unable to develop larger feeding structures

  1. Development of environmental tools for anopheline larval control.

    Science.gov (United States)

    Imbahale, Susan S; Mweresa, Collins K; Takken, Willem; Mukabana, Wolfgang R

    2011-07-06

    Malaria mosquitoes spend a considerable part of their life in the aquatic stage, rendering them vulnerable to interventions directed to aquatic habitats. Recent successes of mosquito larval control have been reported using environmental and biological tools. Here, we report the effects of shading by plants and biological control agents on the development and survival of anopheline and culicine mosquito larvae in man-made natural habitats in western Kenya. Trials consisted of environmental manipulation using locally available plants, the introduction of predatory fish and/or the use of Bacillus thuringiensis var. israelensis (Bti) in various combinations. Man-made habitats provided with shade from different crop species produced significantly fewer larvae than those without shade especially for the malaria vector Anopheles gambiae. Larval control of the African malaria mosquito An. gambiae and other mosquito species was effective in habitats where both predatory fish and Bti were applied, than where the two biological control agents were administered independently. We conclude that integration of environmental management techniques using shade-providing plants and predatory fish and/or Bti are effective and sustainable tools for the control of malaria and other mosquito-borne disease vectors.

  2. Development of environmental tools for anopheline larval control

    Directory of Open Access Journals (Sweden)

    Mweresa Collins K

    2011-07-01

    Full Text Available Abstract Background Malaria mosquitoes spend a considerable part of their life in the aquatic stage, rendering them vulnerable to interventions directed to aquatic habitats. Recent successes of mosquito larval control have been reported using environmental and biological tools. Here, we report the effects of shading by plants and biological control agents on the development and survival of anopheline and culicine mosquito larvae in man-made natural habitats in western Kenya. Trials consisted of environmental manipulation using locally available plants, the introduction of predatory fish and/or the use of Bacillus thuringiensis var. israelensis (Bti in various combinations. Results Man-made habitats provided with shade from different crop species produced significantly fewer larvae than those without shade especially for the malaria vector Anopheles gambiae. Larval control of the African malaria mosquito An. gambiae and other mosquito species was effective in habitats where both predatory fish and Bti were applied, than where the two biological control agents were administered independently. Conclusion We conclude that integration of environmental management techniques using shade-providing plants and predatory fish and/or Bti are effective and sustainable tools for the control of malaria and other mosquito-borne disease vectors.

  3. Embryonic and larval development of Brycon amazonicus (SPIX & AGASSIZ, 1829

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    A. C. S. Sampaio Nakauth

    Full Text Available Abstract The objective of this study was to describe the embryonic and larval development of Brycon amazonicus, featuring the main events up to 50 hours after fertilization (AF. The material was provided by the Aquaculture Training, Technology and Production Center, Presidente Figueiredo (AM. The characterization was based on stereomicroscopic examination of the morphology of eggs, embryos and larvae and comparison with the literature. Matrinxã eggs are free, transparent, and spherical, with a perivitelline space of 0.56 ± 0.3 mm. The successive divisions give rise to cells with 64 blastomeres during the first hour AF. The gastrula stage, beginning 02 h 40 min AF, was characterized by progressive regression cells and the formation of the embryonic axis, leading to differentiation of the head and tail 05 h 30 min AF. From 06 to 09 h AF the somites, notochord, otic and optic vesicles and otoliths were observed, in addition to heart rate and the release of the tail. The larvae hatched at 10 h 30 min AF (29.9 °C, with a total length of 3.56 ± 0.46 mm. Between 19 and 30 h AF, we observed 1 pigmentation and gut formation, 2 branchial arches, 3 pectoral fins, 4 a mouth opening and 5 teeth. Cannibalism was initiated earlier (34 h AF which was associated with rapid yolk absorption (more than 90% until 50 h AF, signaling the need for an exogenous nutritional source. The environmental conditions (especially temperature influenced the time course of some events throughout the embryonic and larval development, suggesting the need for further studies on this subject.

  4. Ascorbic Acid Influences the Development and Immunocompetence of Larval Heliothis virescens

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    We report that ascorbic acid, which is known to be a free radical scavenger, to be important not only in insect development but also in larval resistance to baculovirus infection. We sequentially elevated the ascorbic acid content in diet and evaluated the effect on larval H. virescens development ...

  5. Correlated evolution between mode of larval development and habitat in muricid gastropods.

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    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.

  6. Correlated evolution between mode of larval development and habitat in muricid gastropods.

    Directory of Open Access Journals (Sweden)

    Paula Pappalardo

    Full Text Available Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule, which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in

  7. The effect of rearing temperature in larval development of pejerrey, Odontesthes bonariensis: morphological indicators of development

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    Tomás Chalde

    Full Text Available It is well known that in pejerrey water temperature not only affects growth rates but also directs the sexual differentiation process. This fact rise the question of how different the development of pejerrey larvae of the same age is when reared at different temperatures. A description of developmental stages for the embryonic and larval periods of the pejerrey, Odontesthes bonariensis, and the influence of rearing temperature on larval development are presented. Then, larval development was studied at three rearing temperatures, and changes in general morphology, fin morphology, and caudal fin structure have been taken into consideration within the thermal range involved in the temperature sex determination of this species. Fin fold reabsorption, caudal fin formation, and body shape were selected to follow the events leading to the acquisition of the juvenile morphology. The juvenile phenotype was defined when the fin fold was reabsorpted and the caudal fin acquired its definitive homocercal structure. The moment at which the juvenile phenotype was achieved, was evaluated in relation to larval age, size and, shape. The size resulted as the best indicator of development in pejerrey.

  8. Development of environmental tools for anopheline larval control

    NARCIS (Netherlands)

    Imbahale, S.S.; Mweresa, C.K.; Takken, W.; Mukabana, W.R.

    2011-01-01

    Background: Malaria mosquitoes spend a considerable part of their life in the aquatic stage, rendering them vulnerable to interventions directed to aquatic habitats. Recent successes of mosquito larval control have been reported using environmental and biological tools. Here, we report the effects

  9. Development of environmental tools for anopheline larval control

    NARCIS (Netherlands)

    Imbahale, S.S.; Mweresa, C.K.; Takken, W.; Mukabana, W.R.

    2011-01-01

    Background: Malaria mosquitoes spend a considerable part of their life in the aquatic stage, rendering them vulnerable to interventions directed to aquatic habitats. Recent successes of mosquito larval control have been reported using environmental and biological tools. Here, we report the effects o

  10. Control of larval and egg development in Aedes aegypti with RNA interference against juvenile hormone acid methyl transferase.

    Science.gov (United States)

    Van Ekert, Evelien; Powell, Charles A; Shatters, Robert G; Borovsky, Dov

    2014-11-01

    RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including mosquitoes and many other insects. Little has been done, however, to harness this approach in order to control adult and larval mosquitoes. Juvenile hormone (JH) plays a pivotal role in the control of reproduction in adults and metamorphism in larval mosquitoes. This report describes an approach to control Aedes aegypti using RNAi against JH acid methyl transferase (AeaJHAMT), the ultimate enzyme in the biosynthetic pathway of JH III that converts JH acid III (JHA III) into JH III. In female A. aegypti that were injected or fed jmtA dsRNA targeting the AeaJHAMT gene (jmtA) transcript, egg development was inhibited in 50% of the treated females. In mosquito larvae that were fed transgenic Pichia pastoris cells expressing long hair pin (LHP) RNA, adult eclosion was delayed by 3 weeks causing high mortality. Northern blot analyses and qPCR studies show that jmtA dsRNA causes inhibition of jmtA transcript in adults and larvae, which is consistent with the observed inhibition of egg maturation and larval development. Taken together, these results suggest that jmtA LHP RNA expressed in heat inactivated genetically modified P. pastoris cells could be used to control mosquito populations in the marsh.

  11. The Adult Body Plan of Indirect Developing Hemichordates Develops by Adding a Hox-Patterned Trunk to an Anterior Larval Territory.

    Science.gov (United States)

    Gonzalez, Paul; Uhlinger, Kevin R; Lowe, Christopher J

    2017-01-09

    Many animals are indirect developers with distinct larval and adult body plans [1]. The molecular basis of differences between larval and adult forms is often poorly understood, adding a level of uncertainty to comparative developmental studies that use data from both indirect and direct developers. Here we compare the larval and adult body plans of an indirect developing hemichordate, Schizocardium californicum [2]. We describe the expression of 27 transcription factors with conserved roles in deuterostome ectodermal anteroposterior (AP) patterning in developing embryos, tornaria larvae, and post-metamorphic juveniles and show that the tornaria larva of S. californicum is transcriptionally similar to a truncated version of the adult. The larval ectoderm has an anterior molecular signature, while most of the trunk, defined by the expression of hox1-7, is absent. Posterior ectodermal activation of Hox is initiated in the late larva prior to metamorphosis, in preparation for the transition to the adult form, in which the AP axis converges on a molecular architecture similar to that of the direct developing hemichordate Saccoglossus kowalevskii. These results identify a molecular correlate of a major difference in body plan between hemichordate larval and adult forms and confirm the hypothesis that deuterostome larvae are "swimming heads" [3]. This will allow future comparative studies with hemichordates to take into account molecular differences caused by early life history evolution within the phylum. Additionally, comparisons with other phyla suggest that a delay in trunk development is a feature of indirect development shared across distantly related phyla. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Influence of generation and photoperiod on larval development of Lobesia botrana (Lepidoptera: Tortricidae).

    Science.gov (United States)

    Pavan, Francesco; Floreani, Chiara; Barro, Paola; Zandigiacomo, Pietro; Montà, Laura Dalla

    2010-10-01

    The influence of generation (under field conditions) and photoperiod (under laboratory conditions) on Lobesia botrana larvae development was studied. Some larvae were collected during three annual generations in two grape-growing areas of northeastern Italy, and others were individually reared in the laboratory from egg to pupa on an artificial diet under two different photoperiod conditions (respectively, daylight 16 h/d [long day {LD}] and 14 h/d [short day {SD}]). The mandible lengths of collected larvae were measured and the data analyzed morphometrically to determine the number of larval instars. In the laboratory study, the number of larval moultings, the mandible length of each instar, the development time from hatching larva to pupa, and the pupal weight were considered. The measurement of mandible lengths of larvae collected in the field indicated the existence of five larval instars in all three annual generations, but the size of the two oldest larval instars was significantly higher for third-generation larvae than for the previous generations. Under laboratory conditions, the larvae usually exhibited five instars, but the mandible lengths of larvae and the pupa size were greater for individuals reared under SD. These also took a greater number of days to develop from hatching larvae to pupae. Because a larger size of the final larval instar occurs in individuals that produce diapausing pupae under SD in both the laboratory and the field, a positive association between larval size and the probability of surviving the winter can be inferred.

  13. Muscle organizers in Drosophila: the role of persistent larval fibers in adult flight muscle development

    Science.gov (United States)

    Farrell, E. R.; Fernandes, J.; Keshishian, H.

    1996-01-01

    In many organisms muscle formation depends on specialized cells that prefigure the pattern of the musculature and serve as templates for myoblast organization and fusion. These include muscle pioneers in insects and muscle organizing cells in leech. In Drosophila, muscle founder cells have been proposed to play a similar role in organizing larval muscle development during embryogenesis. During metamorphosis in Drosophila, following histolysis of most of the larval musculature, there is a second round of myogenesis that gives rise to the adult muscles. It is not known whether muscle founder cells organize the development of these muscles. However, in the thorax specific larval muscle fibers do not histolyze at the onset of metamorphosis, but instead serve as templates for the formation of a subset of adult muscles, the dorsal longitudinal flight muscles (DLMs). Because these persistent larval muscle fibers appear to be functioning in many respects like muscle founder cells, we investigated whether they were necessary for DLM development by using a microbeam laser to ablate them singly and in combination. We found that, in the absence of the larval muscle fibers, DLMs nonetheless develop. Our results show that the persistent larval muscle fibers are not required to initiate myoblast fusion, to determine DLM identity, to locate the DLMs in the thorax, or to specify the total DLM fiber volume. However, they are required to regulate the number of DLM fibers generated. Thus, while the persistent larval muscle fibers are not obligatory for DLM fiber formation and differentiation, they are necessary to ensure the development of the correct number of fibers.

  14. Ovarian development and early larval survival of Stenopus zanzibaricus (Bruce, 1976

    Directory of Open Access Journals (Sweden)

    Daniel Marques

    2014-06-01

    Full Text Available Despite economically valuable, ornamental shrimps are poorly studied and there is a lack of protocols for their captive breeding. Stenopus is one of the most important genera of ornamental shrimps, being Stenopus zanzibaricus one of the species with less information about captive breeding and larviculture. For a better knowledge of its reproductive cycle, we evaluated morphological and color changes during ovarian development of adult females through daily photographs taken during all the cycle. The effect of three diets (Brachionus plicatilis + Tetraselmis chuii; newly artemia nauplii + Tetraselmis chuii; newly artemia nauplii and two different temperatures (25ºC and 27ºC on early larval development were also evaluated. With this study, it was expected to obtain some insight about Stenopus zanzibaricus reproductive cycle and early larval development, in order to develop captive breeding and larval rearing protocols for this economic valuable species.

  15. Hox C6 expression during development and regeneration of forelimbs in larval Notophthalmus viridescens.

    Science.gov (United States)

    Khan, P A; Tsilfidis, C; Liversage, R A

    1999-06-01

    A central theme concerning the epimorphic regenerative potential of urodele amphibian appendages is that limb regeneration in the adult parallels larval limb development. Results of previous research have led to the suggestion that homeobox containing genes are "re-expressed" during the epimorphic regeneration of forelimbs of adult Notophthalmus viridescens in patterns which retrace larval limb development. However, to date no literature exists concerning expression patterns of any homeobox containing genes during larval development of this species. The lack of such information has been a hindrance in exploring the similarities as well as differences which exist between limb regeneration in adults and limb development in larvae. Here we report the first such results of the localization of Hox C6 (formerly, NvHBox-1) in developing and regenerating forelimbs of N. viridescens larvae as demonstrated by whole-mount in situ hybridization. Inasmuch as the pattern of Hox C6 expression is similar in developing forelimb buds of larvae and epimorphically regenerating forelimb blastemata of both adults and larvae, our results support the paradigm that epimorphic regeneration in adult newts parallels larval forelimb development. However, in contrast with observations which document the presence of Hox C6 in both intact, as well as regenerating hindlimbs and tails of adult newts, our results reveal no such Hox C6 expression during larval development of hindlimbs or the tail. As such, our findings indicate that critical differences in larval hindlimb and tail development versus adult expression patterns of this gene in these two appendages may be due primarily to differences in gene regulation as opposed to gene function. Thus, the apparent ability of urodeles to regulate genes in such a highly co-ordinated fashion so as to replace lost, differentiated, appendicular structures in adult animals may assist, at least in part, in better elucidating the phenomenon of epimorphic

  16. Does Bilingualism Delay the Development of Dementia?

    Directory of Open Access Journals (Sweden)

    Amy L Atkinson

    2016-08-01

    Full Text Available It has been suggested that bilingualism (where individuals speak two languages may delay the development of dementia. However, much of the research is inconclusive. Some researchers have reported that bilingualism delays the onset and diagnosis of dementia, whilst other studies have found weak or even detrimental effects. This paper reviews a series of nine empirical studies, published up until March 2016, which investigated whether bilingualism significantly delays the onset of dementia. The article also explores whether the inconsistent findings can be attributed to differences in study designs or the definitions of bilingualism used between studies. Based on current evidence, it appears that lifelong bilingualism, where individuals frequently use both languages, may be protective against dementia. However, becoming bilingual in adulthood or using the second language infrequently is unlikely to substantially delay onset of the disease.

  17. Circulation constrains the evolution of larval development modes and life histories in the coastal ocean.

    Science.gov (United States)

    Pringle, James M; Byers, James E; Pappalardo, Paula; Wares, John P; Marshall, Dustin

    2014-04-01

    The evolutionary pressures that drive long larval planktonic durations in some coastal marine organisms, while allowing direct development in others, have been vigorously debated. We introduce into the argument the asymmetric dispersal of larvae by coastal currents and find that the strength of the currents helps determine which dispersal strategies are evolutionarily stable. In a spatially and temporally uniform coastal ocean of finite extent, direct development is always evolutionarily stable. For passively drifting larvae, long planktonic durations are stable when the ratio of mean to fluctuating currents is small and the rate at which larvae increase in size in the plankton is greater than the mortality rate (both in units of per time). However, larval behavior that reduces downstream larval dispersal for a given time in plankton will be selected for, consistent with widespread observations of behaviors that reduce dispersal of marine larvae. Larvae with long planktonic durations are shown to be favored not for the additional dispersal they allow, but for the additional fecundity that larval feeding in the plankton enables. We analyzed the spatial distribution of larval life histories in a large database of coastal marine benthic invertebrates and documented a link between ocean circulation and the frequency of planktotrophy in the coastal ocean. The spatial variation in the frequency of species with planktotrophic larvae is largely consistent with our theory; increases in mean currents lead to a decrease in the fraction of species with planktotrophic larvae over a broad range of temperatures.

  18. Child obesity and motor development delays

    Science.gov (United States)

    Childhood obesity has been associated with delays in motor development using weight-for-length z-scores and subcutaneous fat. To study this further, percent body fat and motor development were assessed in children ages 3 to 24 months. Included were 455 children with a total of 1882 longitudinal obse...

  19. Inhibition of larval development of the marine copepod Acartia tonsa by four synthetic musk substances

    DEFF Research Database (Denmark)

    Wollenberger, Leah; Breitholtz, M.; Kusk, Kresten Ole

    2003-01-01

    ketone) and 2.5 mg/l (Tonalide(TM)). Since, the synthetic musks strongly inhibited larval development in A. tonsa at low nominal concentrations, they should be considered as very toxic. The larval development test with A. tonsa is able to provide important aquatic toxicity data for the evaluation...... of synthetic musks, for which there is little published ecotoxicological information available regarding Crustacea. It is suggested that subchronic and chronic copepod toxicity tests should be used more frequently for risk assessment of environmental pollutants. (C) 2002 Elsevier Science B.V. All rights...

  20. Comparison of two versions of larval development test to detect anthelmintic resistance in Haemonchus contortus.

    Science.gov (United States)

    Várady, Marián; Corba, Július; Letková, Valéria; Kovác, Gabriel

    2009-03-23

    Larval development (LDT) and micro-agar larval development tests (MALDT) were used to compare the reliability and sensitivity of two methods for detecting anthelmintic resistance in Haemonchus contortus. The tests were conducted using three resistant and four susceptible isolates of H. contortus. Both versions of the tests provided comparable results with regard to the characterization of benzimidazole and levamisole susceptibility but neither test was sufficiently sensitive to discrimination between an ivermectin (IVM) susceptible and an IVM resistant isolate. Each test has its own merits with the LDT having the advantage of being less time-consuming.

  1. Exploring Larval Development and Applications in Marine Fish Aquaculture Using Pink Snapper Embryos

    Science.gov (United States)

    Tamaru, Clyde; Haverkort-Yeh, Roxanne D.; Gorospe, Kelvin D.; Rivera, Malia Ana J.

    2014-01-01

    This biology investigation on "Pristipomoides filamentosus" larval development, survival, and aquaculture research was developed with three educational objectives: to provide high school students with (1) a scientific background on the biology and science of fisheries as well as overfishing, its consequences, and possible mitigations;…

  2. Worker honey bee ovary development: seasonal variation and the influence of larval and adult nutrition.

    Science.gov (United States)

    Hoover, Shelley E R; Higo, Heather A; Winston, Mark L

    2006-01-01

    We examined the effect of larval and adult nutrition on worker honey bee (Apis mellifera L.) ovary development. Workers were fed high or low-pollen diets as larvae, and high or low-protein diets as adults. Workers fed low-protein diets at both life stages had the lowest levels of ovary development, followed by those fed high-protein diets as larvae and low- quality diets as adults, and then those fed diets poor in protein as larvae but high as adults. Workers fed high-protein diets at both life stages had the highest levels of ovary development. The increases in ovary development due to improved dietary protein in the larval and adult life stages were additive. Adult diet also had an effect on body mass. The results demonstrate that both carry-over of larval reserves and nutrients acquired in the adult life stage are important to ovary development in worker honey bees. Carry-over from larval development, however, appears to be less important to adult fecundity than is adult nutrition. Seasonal trends in worker ovary development and mass were examined throughout the brood rearing season. Worker ovary development was lowest in spring, highest in mid-summer, and intermediate in fall.

  3. The effect of rearing temperature in larval development of pejerrey, Odontesthes bonariensis: morphological indicators of development

    Directory of Open Access Journals (Sweden)

    Tomás Chalde

    2011-01-01

    Full Text Available It is well known that in pejerrey water temperature not only affects growth rates but also directs the sexual differentiation process. This fact rise the question of how different the development of pejerrey larvae of the same age is when reared at different temperatures. A description of developmental stages for the embryonic and larval periods of the pejerrey, Odontesthes bonariensis, and the influence of rearing temperature on larval development are presented. Then, larval development was studied at three rearing temperatures, and changes in general morphology, fin morphology, and caudal fin structure have been taken into consideration within the thermal range involved in the temperature sex determination of this species. Fin fold reabsorption, caudal fin formation, and body shape were selected to follow the events leading to the acquisition of the juvenile morphology. The juvenile phenotype was defined when the fin fold was reabsorpted and the caudal fin acquired its definitive homocercal structure. The moment at which the juvenile phenotype was achieved, was evaluated in relation to larval age, size and, shape. The size resulted as the best indicator of development in pejerrey.A temperatura da água não afeta apenas as taxas de crescimento no peixe-rei, mas também direciona o processo de diferenciação sexual. Este fato levanta o questionamento de quão diferente é o desenvolvimento de larvas do peixe-rei da mesma idade quando criadas em temperaturas diferentes. Este trabalho teve como objetivo apresentar uma descrição do de desenvolvimento de embriões e larvas do peixe-rei, Odontesthes bonariensis, e a influência da temperatura de criação no desenvolvimento das larvas. Neste trabalho, o desenvolvimento das larvas foi estudado em três temperaturas diferentes de cultivo. Foram consideradas as alterações ocorridas na morfologia geral, assim como na morfologia e na estrutura da nadadeira caudal dentro da variação termal da

  4. A description of the larval development of Megabalanus azoricus (Pilsbry, 1916) reared in the laboratory

    Science.gov (United States)

    Dionísio, Maria; Rodrigues, Armindo; Costa, Ana

    2014-03-01

    This study provides the first description of the larval development of the commercially exploited barnacle Megabalanus azoricus. It describes the changes in larval size and shape as well as the general morphology and duration of each larval stage. Embryos were obtained from gravid specimens collected at São Miguel Island and reared through six naupliar stages to the cypris stage in laboratory conditions. The planktotrophic nauplii reached the cypris stage after 14 days of hatching in individual cultures at 20 °C under natural illumination and fed with phytoplankton ( Chaetoceros gracilis, Isochrysis sp., and Tetraselmis sp.). The nauplius of M. azoricus has a normal size compared with nauplii of other congeneric species, ranging between the 261 μm (nauplius I) and 912 μm (nauplius VI). This work provides the first description of larvae of the genus Megabalanus for the Portuguese oceanic islands and provides comparisons with congeneric species in other parts of the world.

  5. The larval development of Habronema muscae (Nematoda: Habronematidae) affects its intermediate host, Musca domestica (Diptera: Muscidae).

    Science.gov (United States)

    Schuster, Rolf Karl; Sivakumar, Saritha

    2017-02-01

    Although the life cycle of the equid stomach parasite Habronema muscae was disclosed more than 100 years ago, little is known about the effect of the developing nematode larvae in its intermediate host, Musca domestica. In a series of experiments, freshly hatched M. domestica larvae were exposed to H. muscae eggs contained in a faecal sample of a naturally infected horse. In daily intervals, 50 fly larvae were removed and transferred on a parasite-free larval rearing medium where they completed their development. Hatched flies were examined for the presence of Habronema third-stage larvae. In two subsequent control groups, flies spend their entire larval life in contaminated horse faeces and in a parasite-free larval rearing medium, respectively. Out of the 700 fly larvae used in the infection experiments, 304 developed into adult flies of which 281 were infected. The average nematode larval burden rose from 3.6 in the group with the shortest exposure to more than 25 in the groups with the longest exposure. The proportion of larvae that developed into the adult insect fell from 82 % in the uninfected control group to 27 % in the positive control group. The pupae of the positive control group were smaller and lighter than those of the uninfected control group. Lower pupal size and weight in the positive control group as well as a lower insect developing rate might be attributed to the destruction of adipose cells in the maggots by Habronema larvae.

  6. Influence of food concentration, temperature and salinity on the larval development of Balanus amphitrite

    Digital Repository Service at National Institute of Oceanography (India)

    Anil, A.C.; Kurian, J.

    Influence of food concentration (0.5, 1 and 2 x 10 sup(5) cell ml sup(-1) of Skeletonema costatum), temperature (20 and 30 degrees C) and salinity (15, 25 and 35 ppt) on the larval development of Balanus amphitrite (Cirripedia: Thoracica...

  7. Plasma Trace Metals Change Due to Development and Baculovirus Infection in Larval Heliothis virescens

    Science.gov (United States)

    We studied how biologically relevant trace metals (i.e, micronutrients) in the plasma of larvae of Heliothis virescens and Helicoverpa zea (Lepidoptera:Noctuidae) changed in response to larval development, per os baculovirus infection, and injection of heat-killed bacteria. Levels of plasma Co, Cr,...

  8. Development of a larval diet for the South American fruit fly Anastrepha fraterculus (Diptera:Tephritidae)

    Science.gov (United States)

    Mass-rearing protocols must be developed. In particular, a cost-effective larval diet, to implement the sterile insect technique against Anastrepha fratercculus (Wiedemann). The key elements of this diet are the optimal nutrients and their concentrations, diet supports or bulking agents, and the pH ...

  9. Inhibition of larval development of the marine copepod Acartia tonsa by four synthetic musk substances.

    Science.gov (United States)

    Wollenberger, Leah; Breitholtz, Magnus; Ole Kusk, Kresten; Bengtsson, Bengt Erik

    2003-04-15

    A nitro musk (musk ketone) and three polycyclic musks (Tonalide, Galaxolide and Celestolide) were tested for acute and subchronic effects on a marine crustacean, the calanoid copepod Acartia tonsa. Sublethal effects on A. tonsa larvae were investigated with a rapid and cost effective bioassay, which is based on the easily detectable morphological change from the last nauplius to the first copepodite stage during copepod larval development. The inhibition of larval development after 5 days exposure was a very sensitive endpoint, with 5-d-EC(50)-values as low as 0.026 mg/l (Tonalide), 0.059 mg/l (Galaxolide), 0.066 mg/l (musk ketone) and 0.160 mg/l (Celestolide), respectively. These values were generally more than one order of magnitude below the 48-h-LC(50)-values found for adults, which were 0.47 mg/l (Galaxolide), 0.71 mg/l (Celestolide), 1.32 mg/l (musk ketone) and 2.5 mg/l (Tonalide). Since the synthetic musks strongly inhibited larval development in A. tonsa at low nominal concentrations, they should be considered as very toxic. The larval development test with A. tonsa is able to provide important aquatic toxicity data for the evaluation of synthetic musks, for which there is little published ecotoxicological information available regarding Crustacea. It is suggested that subchronic and chronic copepod toxicity tests should be used more frequently for risk assessment of environmental pollutants.

  10. RELATION BETWEEN STRESS COPING STYLE, LARVAL DEVELOPMENT AND TIME TO EMERGANCE IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    DEFF Research Database (Denmark)

    Steffensen, John Fleng

    2010-01-01

    behavior. In salmonids, differences in larval development have been related to these styles. In this study we investigated larval development and time to emergence in two strains of Rainbow trout selected for low (LR) and high (HR) post stress plasma cortisol levels. These strains have previously been......Åberg, Madelene, Uniza Kahn, John Fleng Steffensen, Øyvind Øverli, Hans Magnus Gjoen and Erik Höglund Abstract: Proactive and reactive stress coping styles is widespread amongst animal groups. Reactive individuals are generally shy and subordinate whereas proactive individuals show the opposite...... characterized with proactive and reactive stress coping, respectively. A line specific SNP was used to distinguish the emerging larvae and a clear link between stress coping style and emergence time was demonstrated by LR larvae emerging earlier than HR larvae. LR larvae also had more yolk reserves at the time...

  11. Acute exposure to tris (2-butoxyethyl) phosphate (TBOEP) affects growth and development of embryo-larval zebrafish.

    Science.gov (United States)

    Liu, Yiran; Wu, Ding; Xu, Qinglong; Yu, Liqin; Liu, Chunsheng; Wang, Jianghua

    2017-10-01

    Tris (2-butoxyethyl) phosphate (TBOEP), is used as a flame retardant worldwide. It is an additive in materials and can be easily discharged into the surrounding environment. There is evidence linking TBOEP exposure to abnormal development and growth in zebrafish embryos/larvae. Here, using zebrafish embryo as a model, we investigated toxicological effects on developing zebrafish (Danio rerio) caused by TBOEP at concentrations of 0, 20, 200, 1000, 2000μg/L starting from 2h post-fertilization (hpf). Our findings revealed that TBOEP exposure caused developmental toxicity, such as malformation, growth delay and decreased heart rate in zebrafish larvae. Correlation analysis indicated that inhibition of growth was possibly due to down-regulation of expression of genes related to the growth hormone/insulin-like growth factor (GH/IGF) axis. Furthermore, exposure to TBOEP significantly increased thyroxine (T4) and 3,5,3'-triiodothyronine (T3) in whole larvae. In addition, changed expression of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis was observed, indicating that perturbation of HPT axis might be responsible for the developmental damage and growth delay induced by TBOEP. The present study provides a new set of evidence that exposure of embryo-larval zebrafish to TBOEP can cause perturbation of GH/IGF axis and HPT axis, which could result in developmental impairment and growth inhibition. Copyright © 2017. Published by Elsevier B.V.

  12. EFFECTS OF THALLIUM ON THE LARVAL DEVELOPMENT OF LUCILIA SERICATA MEIGEN 1826 AND PMI ESTIMATION

    Directory of Open Access Journals (Sweden)

    Arif Gökhan BAŞARAN

    2011-08-01

    Full Text Available Determination of larval growth rate of and forensic analysis of the age of Calliphoridae larvae on a corpse are useful evidence in legal investigations for the estimation of exact death time and time duration after death; post mortem interval. However many factors, such as temperature, tissue type and contamination of drugs and toxins, effect larval development of blow fly larvae and consequently theestimation of post mortem interval. The present study examined the larval growth rate of a forensically important blow fly species, Lucilia sericata Meigen 1826 in different concentrations (0,12; 0,25; 0,50; 1 and 2 μg/g of toxic heavy metal Thallium under controlled laboratory conditions. Body length and weight, death ratio of larvae and pupa between experimental and control groups were compared. Results demonstrated that the development rate of larvae between uncontaminated and contaminated diets varies significantly. In short, they molted later, reached maximum length more slowly and sometimesproduced significantly smaller pupae in contaminated food source. These results emphasized that the importance of determining the contamination rate of toxins in tissue for the forensic entomologist,while using development rates from standard curves based on larvae fed non-contaminated mediums.

  13. Larval Development of Two N. E. Pacific Pilidiophoran Nemerteans (Heteronemertea; Lineidae).

    Science.gov (United States)

    Hiebert, Terra C; Maslakova, Svetlana A

    2015-12-01

    Unique to the phylum Nemertea, the pilidium is an unmistakable planktonic larva found in one group of nemerteans, the Pilidiophora. Inside the pilidium, the juvenile develops from a series of epidermal invaginations in the larval body, called imaginal discs. The discs grow and fuse around the larval gut over the course of weeks to months in the plankton. Once complete, the juvenile breaks free from the larval body in a catastrophic metamorphosis, and often devours the larva as its first meal. One third of nemertean species are expected to produce a pilidium, but the larvae are known for very few species; development from fertilization to metamorphosis has been described in only one species, Micrura alaskensis. Known pilidia include both planktotrophic and lecithotrophic forms, and otherwise exhibit great morphological diversity. Here, we describe the complete development in two lineiform species that are common to the northeast Pacific coast, Micrura wilsoni and Lineus sp. "red." Both species possess typical, cap-shaped planktotrophic pilidia, and the order of emergence of imaginal discs is similar to that which is described in M. alaskensis. The pilidium of Lineus sp. "red" resembles pilidia of several other species, such as Lineus flavescens, and potentially characterizes a pilidiophoran clade. M. wilsoni has relatively transparent oocytes and a pilidium with what appears to be a unique pattern of pigmentation. The adults of both species are more commonly observed in intertidal zones than their larvae are in the plankton. © 2015 Marine Biological Laboratory.

  14. Leachate from microplastics impairs larval development in brown mussels.

    Science.gov (United States)

    Gandara E Silva, Pablo Pena; Nobre, Caio Rodrigues; Resaffe, Pryscila; Pereira, Camilo Dias Seabra; Gusmão, Felipe

    2016-12-01

    Microplastic debris is a pervasive type of contaminant in marine ecosystems, being considered a major threat to marine biota. One of the problems of microplastics is that they can adsorb contaminants in extremely high concentrations. When released from the particle, these contaminants have the potential to cause toxic effects in the biota. So far, reports of toxic effects are mostly linked with the direct exposure of organisms through ingestion of contaminated microplastics. There is little information on the toxicity of leachates from microplastics to marine organisms. In this study, we conducted experiments to evaluate the toxicity of leachates from virgin and beached plastic pellets to embryo development of the brown mussel (Perna perna). We compared the efficiency of two test procedures, and evaluated the toxicity of beached pellets collected in a coastal marine protected area. We observed that mussel embryo is sensitive to leachate from both virgin and beached pellets. However, the toxicity of the leachate from beached pellets was much higher than that of virgin pellets. We suggest contaminants adsorbed onto the surface of beached pellets were responsible for the high toxicity of leachate from beached pellets, while the toxicity of leachate from virgin pellets was mainly due to plastic additives. Our results suggest microplastic debris may be harmful even if ingestion is not the only or main pathway of interaction of marine organisms with contaminated plastic debris.

  15. HAMLET treatment delays bladder cancer development.

    Science.gov (United States)

    Mossberg, Ann-Kristin; Hou, Yuchuan; Svensson, Majlis; Holmqvist, Bo; Svanborg, Catharina

    2010-04-01

    HAMLET is a protein-lipid complex that kills different types of cancer cells. Recently we observed a rapid reduction in human bladder cancer size after intravesical HAMLET treatment. In this study we evaluated the therapeutic effect of HAMLET in the mouse MB49 bladder carcinoma model. Bladder tumors were established by intravesical injection of MB49 cells into poly L-lysine treated bladders of C57BL/6 mice. Treatment groups received repeat intravesical HAMLET instillations and controls received alpha-lactalbumin or phosphate buffer. Effects of HAMLET on tumor size and putative apoptotic effects were analyzed in bladder tissue sections. Whole body imaging was used to study HAMLET distribution in tumor bearing mice compared to healthy bladder tissue. HAMLET caused a dose dependent decrease in MB49 cell viability in vitro. Five intravesical HAMLET instillations significantly decreased tumor size and delayed development in vivo compared to controls. TUNEL staining revealed selective apoptotic effects in tumor areas but not in adjacent healthy bladder tissue. On in vivo imaging Alexa-HAMLET was retained for more than 24 hours in the bladder of tumor bearing mice but not in tumor-free bladders or in tumor bearing mice that received Alexa-alpha-lactalbumin. Results show that HAMLET is active as a tumoricidal agent and suggest that topical HAMLET administration may delay bladder cancer development. Copyright (c) 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  16. The impact of food type, temperature and starvation on larval development of Balanus amphitrite Darwin (Cirripedia: Thoracica)

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.; Anil, A.C.

    The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day...

  17. Development of the compound eyes of dragonflies (Odonata). II. Development of the larval compound eyes.

    Science.gov (United States)

    Sherk, T E

    1978-01-01

    The development of the compound eye was analyzed by marking individual ommatidia and by studying naturally occurring pigment band patterns. New ommatidia are added to the eye along its anterior margin. This changes the directions of view of the older ommatidia with the greatest change occurring in the fovea. New ommatidia are added to the fovea medially, and old ones are removed laterally as their interommatidial angles and directions of view in the visual field change. Over one-third of the aeshnid ommatidia are foveal during at least one of the early larval instars, and are then used for peripheral vision later in development. The design of each ommatidium is a compromise so that it is adapted for all stages of development, but sometimes better adapted for one instar than for others. Factors which are balanced for best vision are lens diameter, facet admission function, interommatidial angle, and inclination of the optic axis to the eye surface. Ommatidia are described in terms of these factors throughout their life history, from initial differentiation anteriorly, through passage through the fovea, to their final relatively posterior location.

  18. Temperature- and sex-related effects of serine protease alleles on larval development in the Glanville fritillary butterfly.

    Science.gov (United States)

    Ahola, V; Koskinen, P; Wong, S C; Kvist, J; Paulin, L; Auvinen, P; Saastamoinen, M; Frilander, M J; Lehtonen, R; Hanski, I

    2015-12-01

    The body reserves of adult Lepidoptera are accumulated during larval development. In the Glanville fritillary butterfly, larger body size increases female fecundity, but in males fast larval development and early eclosion, rather than large body size, increase mating success and hence fitness. Larval growth rate is highly heritable, but genetic variation associated with larval development is largely unknown. By comparing the Glanville fritillary population living in the Åland Islands in northern Europe with a population in Nantaizi in China, within the source of the post-glacial range expansion, we identified candidate genes with reduced variation in Åland, potentially affected by selection under cooler climatic conditions than in Nantaizi. We conducted an association study of larval growth traits by genotyping the extremes of phenotypic trait distributions for 23 SNPs in 10 genes. Three genes in clip-domain serine protease family were associated with larval growth rate, development time and pupal weight. Additive effects of two SNPs in the prophenoloxidase-activating proteinase-3 (ProPO3) gene, related to melanization, showed elevated growth rate in high temperature but reduced growth rate in moderate temperature. The allelic effects of the vitellin-degrading protease precursor gene on development time were opposite in the two sexes, one genotype being associated with long development time and heavy larvae in females but short development time in males. Sexually antagonistic selection is here evident in spite of sexual size dimorphism.

  19. CCDC-55 is required for larval development and distal tip cell migration in Caenorhabditis elegans.

    Science.gov (United States)

    Kovacevic, Ismar; Ho, Richard; Cram, Erin J

    2012-01-01

    The Caenorhabditis elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study, we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC.

  20. Effect of Salinity on Embryo and Larval Development of Oyster Crassostrea iredalei.

    Science.gov (United States)

    Fang, Amelia Ng Phei; Peng, Teh Chiew; Yen, Poi Khoy; Yasin, Zulfigar; Hwai, Aileen Tan Shau

    2016-11-01

    The effects of salinity on the embryonic and larvae stage of Crassostrea iredalei were investigated. Fertilised eggs and one day old D-larvae were subjected to salinities ranging from 0 to 30 ppt at temperature of 30±2°C. At salinity lower than 10 ppt, 100% mortality was observed. For embryo development, the highest survival was observed at salinity 25 ppt with 80.9±2.2% survival with no significant difference compared to 15 and 30 ppt. Shell height and length were both greatest at salinity 30 ppt. Throughout the 11 days culture, the highest larval survival occurred at salinity 15 ppt with no significant difference compared to all other salinities except 10 ppt. Larval shell sizes showed no significant differences between salinities, except for 10 ppt. Optimum culture condition for larvae growth are salinities ranging from 15 to 30 ppt whereby the larval of this species can tolerate wider range of salinity compared to other oyster species and thus, making it a competitive species to be cultured.

  1. Artificial substrates for oviposition and larval development of the pepper weevil (Coleoptera: Curculionidae).

    Science.gov (United States)

    Addesso, K M; McAuslane, H J; Stansly, P A; Slansky, F; Schuster, D J

    2009-02-01

    The pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae), is a major pest of cultivated peppers (Capsicum spp.) and other cultivated and wild species within the family Solanaceae. Laboratory study of this insect, as well as its biological control agents, will be greatly facilitated by an artificial rearing system that does not rely on pepper fruit. An egg collection method and amendments to a standard larval diet were investigated for use in the rearing of this weevil. Spherical sachets made of Parafilm or netting enclosing leaves of pepper, American black nightshade, eggplant, tomato, potato, and jasmine tobacco induced oviposition. Tomato, potato, and jasmine tobacco leaves were accepted despite the fact that these are not oviposition hosts for pepper weevils in the wild. A standard larval diet formula was modified in an attempt to improve egg hatch, larval survival, developmental time, and adult mass. The diet formula was modified with the addition of freeze-dried jalapeño pepper powder, an additional lipid source, alternate protein sources, and the removal of methyl paraben. None of the aforementioned treatments resulted in a significant improvement over the standard diet. Egg hatch was greater when eggs were incubated on moist paper towels rather than in diet; thus, placement of neonates rather than eggs into diet improved production of adults. Suggestions for more efficient rearing of weevils on the currently available diet and future directions for the development of an artificial rearing system for pepper weevil are discussed.

  2. CCDC-55 is required for larval development and distal tip cell migration in C. elegans

    Science.gov (United States)

    Kovacevic, Ismar; Ho, Richard; Cram, Erin J.

    2012-01-01

    The C. elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC. PMID:22285439

  3. Development of the larval anterior neurogenic domains of Terebratalia transversa (Brachiopoda provides insights into the diversification of larval apical organs and the spiralian nervous system

    Directory of Open Access Journals (Sweden)

    Santagata Scott

    2012-01-01

    Full Text Available Abstract Background Larval features such as the apical organ, apical ciliary tuft, and ciliated bands often complicate the evaluation of hypotheses regarding the origin of the adult bilaterian nervous system. Understanding how neurogenic domains form within the bilaterian head and larval apical organ requires expression data from animals that exhibit aspects of both centralized and diffuse nervous systems at different life history stages. Here, we describe the expression of eight neural-related genes during the larval development of the brachiopod, Terebratalia transversa. Results Radially symmetric gastrulae broadly express Tt-Six3/6 and Tt-hbn in the animal cap ectoderm. Tt-NK2.1 and Tt-otp are restricted to a central subset of these cells, and Tt-fez and Tt-FoxQ2 expression domains are already asymmetric at this stage. As gastrulation proceeds, the spatial expression of these genes is split between two anterior ectodermal domains, a more dorsal region comprised of Tt-Six3/6, Tt-fez, Tt-FoxQ2, and Tt-otp expression domains, and an anterior ventral domain demarcated by Tt-hbn and Tt-NK2.1 expression. More posteriorly, the latter domains are bordered by Tt-FoxG expression in the region of the transverse ciliated band. Tt-synaptotagmin 1 is expressed throughout the anterior neural ectoderm. All genes are expressed late into larval development. The basiepithelial larval nervous system includes three neurogenic domains comprised of the more dorsal apical organ and a ventral cell cluster in the apical lobe as well as a mid-ventral band of neurons in the mantle lobe. Tt-otp is the only gene expressed in numerous flask-shaped cells of the apical organ and in a subset of neurons in the mantle lobe. Conclusions Our expression data for Tt-Six3/6, Tt-FoxQ2, and Tt-otp confirm some aspects of bilaterian-wide conservation of spatial partitioning within anterior neurogenic domains and also suggest a common origin for central otp-positive cell types within

  4. Larval development of Cyrtograpsus affinis (Dana (Decapoda, Brachyura, Varunidae from Río de la Plata estuary, reared in the laboratory

    Directory of Open Access Journals (Sweden)

    Eduardo D. Spivak

    2000-03-01

    Full Text Available The complete larval development of the crab Cyrtograpsus affinis (Brachyura, Varunidae was obtained by culture in the laboratory. Five zoeal stages, the megalopa and the first crab are described and illustrated. Larval development from hatching to first crab took 29 days at 20° C and 35 PSU. The genus Cyrtograpsus only consists of three species. Larval development of C. altimanus and C. angulatus had been described previously. In the present study, morphological larval characters of the three species are compared. Generic larval features are also compared with those of other Varunidae genera.

  5. Role of bacteria in the oviposition behaviour and larval development of stable flies.

    Science.gov (United States)

    Romero, A; Broce, A; Zurek, L

    2006-03-01

    Stable flies, Stomoxys calcitrans (L.), are the most important pests of cattle in the United States. However, adequate management strategies for stable flies, especially for pastured cattle, are lacking. Microbial/symbiont-based approaches offer novel venues for management of insect pests and/or vector-borne human and animal pathogens. Unfortunately, the fundamental knowledge of stable fly-microbial associations and their effect on stable fly biology is lacking. In this study, stable flies laid greater numbers of eggs on a substrate with an active microbial community (> 95% of total eggs oviposited) than on a sterilized substrate. In addition, stable fly larvae could not develop in a sterilized natural or artificial substrate/medium. Bacteria were isolated and identified from a natural stable fly oviposition/developmental habitat and their individual effect on stable fly oviposition response and larval development was evaluated in laboratory bioassays. Of nine bacterial strains evaluated in the oviposition bioassays, Citrobacter freundii stimulated oviposition to the greatest extent. C. freundii also sustained stable fly development, but to a lesser degree than Serratia fanticola. Serratia marcescens and Aeromonas spp. neither stimulated oviposition nor supported stable fly development. These results demonstrate a stable fly bacterial symbiosis; stable fly larval development depends on a live microbial community in the natural habitat, and stable fly females are capable of selecting an oviposition site based on the microbially derived stimuli that indicate the suitability of the substrate for larval development. This study shows a promising starting point for exploiting stable fly-bacterial associations for development of novel approaches for stable fly management.

  6. Grass Pollen Affects Survival and Development of Larval Anopheles arabiensis (Diptera: Culicidae)

    Science.gov (United States)

    Asmare, Yelfwagash; Hopkins, Richard J; Tekie, Habte; Hill, Sharon R

    2017-01-01

    Abstract Nutrients in breeding sites are critical for the survival and development of malaria mosquitoes, having a direct impact on vectorial capacity. Yet, there is a limited understanding about the natural larval diet and its impact on the individual fitness of mosquitoes. Recent studies have shown that gravid Anopheles arabiensis Patton (Diptera: Culicidae) are attracted by and oviposit in grass-associated habitats. The pollen provided by these grasses is a potential source of nutrients for the larvae. Here, we assess the effect of Typha latifolia L. (Poales: Typhaceae), Echinochloa pyramidalis Lamarck, Pennisetum setaceum Forsskål, and Zea mays L. pollen on larval survival and rate of development in An. arabiensis under laboratory conditions. In addition, we characterize the carbon to nitrogen ratio and the size of pollen grains as a measure of diet quality. Carbon-rich pollen with a small grain size (T. latifolia and P. setaceum; 9.7 ± 0.3 × 103 and 5.5 ± 0.2 × 104 µm3, respectively) resulted in enhanced rates of development of An. arabiensis. In contrast, the larva fed on the nitrogen-rich control diet (TetraMin) was slower to develop, but demonstrated the highest larval survival. Larvae fed on carbon-rich and large-grained Z. mays pollen (4.1 ± 0.2 × 105 µm3) survived at similar levels as those fed on the control diet and also took a longer time to develop compared with larvae fed on the other pollens. While males and females did not appear to develop differently on the different pollen diets, males consistently emerged faster than their female counterparts. These results are discussed in relation to integrated vector management.

  7. Scymnus camptodromus (Coleoptera: Coccinellidae) Larval Development and Predation of Hemlock Woolly Adelgid (Hemiptera: Adelgidae).

    Science.gov (United States)

    Limbu, Samita; Keena, Melody A; Long, David; Ostiguy, Nancy; Hoover, Kelli

    2015-02-01

    Development time and prey consumption of Scymnus (Neopullus) camptodromus Yu and Liu (Coleoptera: Coccinellidae) larvae by instar, strain, and temperature were evaluated. S. camptodromus, a specialist predator of hemlock woolly adelgid Adelges tsugae (Annand) (Hemiptera: Adelgidae), was brought to the United States from China as a potential biological control agent for A. tsugae. This beetle has been approved for removal from quarantine but has not yet been field released. We observed that temperature had significant effects on the predator's life history. The larvae tended to develop faster and consume more eggs of A. tsugae per day as rearing temperature increased. Mean egg consumption per day of A. tsugae was less at 15°C than at 20°C. However, as larvae took longer to develop at the lower temperature, the total number of eggs consumed per instar during larval development did not differ significantly between the two temperatures. The lower temperature threshold for predator larval development was estimated to be 5°C, which closely matches the developmental threshold of A. tsugae progrediens. Accumulated degree-days for 50% of the predator neonates to reach adulthood was estimated to be 424. Although temperature had a significant effect on larval development and predation, it did not impact survival, size, or sex ratio of the predator at 15 and 20°C. Furthermore, no remarkable distinctions were observed among different geographical populations of the predator. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Significance of bacteria in oviposition and larval development of the sand fly Lutzomyia longipalpis.

    Science.gov (United States)

    Peterkova-Koci, Kamila; Robles-Murguia, Maricela; Ramalho-Ortigao, Marcelo; Zurek, Ludek

    2012-07-24

    Microbial ecology of phlebotomine sand flies is not well understood although bacteria likely play an important role in the sand fly biology and vector capacity for Leishmania parasites. In this study, we assessed the significance of the microbial community of rabbit feces in oviposition and larval development of Lutzomyia longipalpis as well as bacterial colonization of the gut of freshly emerged flies. Sterile (by autoclaving) and non-sterile (control) rabbit feces were used in the two-choice assay to determine their oviposition attractiveness to sand fly females. Bacteria were identified by amplification and sequencing of the 16S rRNA gene with universal eubacterial primers. Sterile, control (non-sterile), and sterilized and inoculated rabbit feces were used to assess the significance of bacteria in L. longipalpis development. Newly emerged adult flies were surface-sterilized and screened for the bacterial population size and diversity by the culturing approach. The digestive tract of L4 sterile and control larvae was incubated with Phalloidin to visualize muscle tissues and DAPI to visualize nuclei. Two-choice behavioural assays revealed a great preference of L. longipalpis to lay eggs on rabbit feces with an active complex bacterial community (control) (85.8 % of eggs) in comparison to that of sterile (autoclaved) rabbit feces (14.2 %). Bioassays demonstrated that L. longipalpis larvae can develop in sterile rabbit feces although development time to adult stage was greatly extended (47 days) and survival of larvae was significantly lower (77.8 %) compared to that of larvae developing in the control rabbit feces (32 days and 91.7 %). Larval survival on sterilized rabbit feces inoculated with the individual bacterial isolates originating from this substrate varied greatly depending on a bacterial strain. Rhizobium radiobacter supported larval development to adult stage into the greatest extent (39 days, 88.0 %) in contrast to that of Bacillus spp

  9. Larval spicules, cilia, and symmetry as remnants of indirect development in the direct developing sea urchin Heliocidaris erythrogramma.

    Science.gov (United States)

    Emlet, R B

    1995-02-01

    Nonfeeding larvae of the echinoid Heliocidaris erythrogramma were raised in culture and examined for expression of a larval skeleton and for the arrangement of the ciliated band. Opaque larvae were fixed, cleared, and examined under polarized light for evidence of calcification. By 35 hr after fertilization (at 22 degrees C), a pair of triradiate spicules was present at the posterior end of the larvae. Each member of this pair formed a fenestrated spicule as it grew laterally. This pair and another pair which formed subsequently, were arranged across a plane of bilateral symmetry orthagonal to the juvenile oral aboral axis. These paired larval spicules can be identified as reduced expressions of postoral and posterodorsal rods found in plutei, and their expression indicates that the juvenile rudiment of H. erythrogramma forms on the left side and that larval body axes are conserved in this modified larva. By 44 hr the ciliated band formed as an incomplete transverse loop of three segments at the posterior end and on the dorsal surface of the ovoid larva. Cilia in these segments grew to lengths of 45-50 microns, longer than other swimming and feeding cilia reported for echinoderm larvae. Band segments are interpreted as expressions of epaulettes (specialized swimming bands) rather than the feeding ciliated band of the pluteus. The ciliated band segments and the larval spicules are both bilaterally symmetrical with respect to the same plane and indicate conserved larval bilateral symmetry despite the major asymmetry of the fates of cells on either side of this plane in their contribution to juvenile development.

  10. Embryonic and larval development of Spisula solidissima similis (Say, 1822) (Bivalvia: Mactridae)

    OpenAIRE

    Walker, R.L.; O Beirn, F. X.

    1996-01-01

    Larvae of the southern surf clam, Spisula solidissima similis (Say, 1822), were reared in the laboratory at a salinity of 25 ppt and a temperature of 20-22°C through the embryonic and early larval development period. Unfertilized eggs averaged 58.5 ± 0.32 (SE) μm, with the size-frequency of eggs being normal. First polar body was observed 22 minutes after fertilization with 50% of eggs exhibiting polar bodies after 26 minutes. Ciliated blastula and trochophore stages occurred at 6 hours an...

  11. Muscle development in the abdominal region of larval Hylidae (Amphibia: Anura).

    Science.gov (United States)

    Manzano, A S; Perotti, M G

    1999-09-01

    Larval muscle development in the abdominal region of five species of hylid frogs (Scinax nasicum, S. fuscovarium, Hyla andina, Phyllomedusa boliviana, Gastrotheca gracilis) was studied using differential staining techniques. These five species represent three major hylid subfamilies. The development of the main abdominal muscles, the rectus abdominis, the two lateral muscles (obliquus externus and transversus), and the lateral pectoralis abdominalis is described. The number of myotomes of the rectus abdominis varies between five and six, and the abdominal muscles associated with the rectus abdominis (obliquus externus, pectoralis abdominalis, and rectus cervicis) vary interspecifically in time of appearance and configuration. The presence of gaps in the configuration of the rectus abdominis has been related to the lotic habits of the larvae. However, our observations indicate the presence of such gaps in larvae that inhabit lentic environments as well. These results suggest that the presence of these gaps is unrelated to larval habitat. There are relatively small differences in muscle morphology among these closely related species, which apparently cannot be explained by morphological adaptations related to their ecology. In the species studied, the number of elements that form the abdominal musculature in larvae is equal to that observed in adults. Likewise, the general morphology of the muscles is ontogenetically conserved. This suggests that both the axial skeleton and musculature are more ontogenetically conserved in relation to the substantial changes that are observed in the skull and head muscles of developing anurans.

  12. Effect of Two Oil Dispersants on Larval Grass Shrimp (Palaemonetes pugio) Development.

    Science.gov (United States)

    Betancourt, P.; Key, P. B.; Chung, K. W.; DeLorenzo, M. E.

    2015-12-01

    The study focused on the effects that two oil dispersants, Corexit® EC9500A and Finasol® OSR52, have on the development of larval grass shrimp, (Palaemonetes pugio). The hypothesis was that Finasol would have a greater effect on larval grass shrimp development than Corexit. The experiment was conducted using 300 grass shrimp larvae that were 24 hours old. Each larva was exposed individually. In total, five sub-lethal concentrations were tested for each dispersant (control, 1.25, 2.50, 5.0,10.0 mg/L). The larvae were exposed for five days then transferred to clean seawater until metamorphosis into the juvenile stage. Key data measurements recorded included number of days to become juveniles, number of instars, length, dry weight, and mortality. Data from exposed shrimp was compared to the results of the control for each dispersant concentration. Corexit and Finasol exposure treatments of 5 mg/L and 10 mg/L showed significantly higher values for number of days and number of instars to reach juvenile status than values obtained from unexposed, control shrimp. Overall, mortality was higher in the Finasol treatments but the two dispersants did not respond significantly different from one another. Future studies are needed to determine the long term effects of dispersant exposure on all grass shrimp life stages and how any dispersant exposure impacts grass shrimp populations. Grass shrimp serve as excellent toxicity indicators of estuaries, and further studies will help to develop better oil spill mitigation techniques.

  13. Reusing larval rearing water and its effect on development and quality of Anopheles arabiensis mosquitoes.

    Science.gov (United States)

    Mamai, Wadaka; Lees, Rosemary Susan; Maiga, Hamidou; Gilles, Jeremie R L

    2016-03-16

    There is growing interest in applying the sterile insect technique (SIT) against mosquitoes. Mass production of mosquitoes for large-scale releases demands a huge amount of water. Yet, many arid and/or seasonally arid countries face the difficulties of acute water shortage, deterioration of water quality and environmental constraints. The re-use of water to rear successive generations of larvae is attractive as a way to reduce water usage and running costs, and help to make this control method viable. To determine whether dirty larval water was a suitable rearing medium for Anopheles arabiensis, in place of the 'clean' dechlorinated water routinely used, a series of three experiments was carried out to evaluate the effect of dirty water or mixed clean and dirty water on several parameters of insect quality. Batches of 100 fresh eggs were distributed in dirty water or added to clean water to test the effect of dirty water on egg hatching, whereas first-instar larvae were used to determine the effect on immature development time, pupation, adult emergence, body size, and longevity. Moreover, to assess the effect of dirty water on larval mortality, pupation rate, adult emergence, and longevity, L4 larvae collected after the tilting or larvae/pupae separation events were returned either to the dirty water or added to clean water. Results indicated that reusing dirty water or using a 50:50 mix of clean and dirty water did not affect egg hatching. Moreover, no difference was found in time to pupation, larval mortality or sex ratio when first-instar larvae were added to clean water, dirty water, or a 75:25, 50:50 or 25:75 mix of clean and dirty water and reared until emergence. When late-instar larvae were put back into their own rearing water, there was no effect on pupation rate, emergence rate or female longevity, though male longevity was reduced. When reared from first-instar larvae, however, dirty water decreased pupation rate, emergence rate, body size, and adult

  14. Rearing Tenebrio molitor in BLSS: Dietary fiber affects larval growth, development, and respiration characteristics

    Science.gov (United States)

    Li, Leyuan; Stasiak, Michael; Li, Liang; Xie, Beizhen; Fu, Yuming; Gidzinski, Danuta; Dixon, Mike; Liu, Hong

    2016-01-01

    Rearing of yellow mealworm (Tenebrio molitor L.) will provide good animal nutrition for astronauts in a bioregenerative life support system. In this study, growth and biomass conversion data of T. molitor larvae were tested for calculating the stoichiometric equation of its growth. Result of a respiratory quotient test proved the validity of the equation. Fiber had the most reduction in mass during T. molitor‧s consumption, and thus it is speculated that fiber is an important factor affecting larval growth of T. molitor. In order to further confirm this hypothesis and find out a proper feed fiber content, T. molitor larvae were fed on diets with 4 levels of fiber. Larval growth, development and respiration in each group were compared and analyzed. Results showed that crude-fiber content of 5% had a significant promoting effect on larvae in early instars, and is beneficial for pupa eclosion. When fed on feed of 5-10% crude-fiber, larvae in later instars reached optimal levels in growth, development and respiration. Therefore, we suggest that crude fiber content in feed can be controlled within 5-10%, and with the consideration of food palatability, a crude fiber of 5% is advisable.

  15. Proteomic analysis during larval development and metamorphosis of the spionid polychaete Pseudopolydora vexillosa

    KAUST Repository

    Mok, Flora SY

    2009-12-14

    Background: While the larval-juvenile transition (metamorphosis) in the spionid polychaete Pseudopolydora vexillosa involves gradual morphological changes and does not require substantial development of juvenile organs, the opposite occurs in the barnacle Balanus amphitrite. We hypothesized that the proteome changes during metamorphosis in the spionids are less drastic than that in the barnacles. To test this, proteomes of pre-competent larvae, competent larvae (ready to metamorphose), and juveniles of P. vexillosa were compared using 2-dimensional gel electrophoresis (2-DE), and they were then compared to those of the barnacle.Results: Unlike the significant changes found during barnacle metamorphosis, proteomes of competent P. vexillosa larvae were more similar to those of their juveniles. Pre-competent larvae had significantly fewer protein spots (384 spots), while both competent larvae and juveniles expressed about 660 protein spots each. Proteins up-regulated during competence identified by MALDI-TOF/TOF analysis included a molecular chaperon (calreticulin), a signal transduction regulator (tyrosin activation protein), and a tissue-remodeling enzyme (metallopeptidase).Conclusions: This was the first time to study the protein expression patterns during the metamorphosis of a marine polychaete and to compare the proteomes of marine invertebrates that have different levels of morphological changes during metamorphosis. The findings provide promising initial steps towards the development of a proteome database for marine invertebrate metamorphosis, thus deciphering the possible mechanisms underlying larval metamorphosis in non-model marine organisms. © 2009 Mok et al; licensee BioMed Central Ltd.

  16. Proteomic analysis during larval development and metamorphosis of the spionid polychaete Pseudopolydora vexillosa

    Directory of Open Access Journals (Sweden)

    Qian Pei-Yuan

    2009-12-01

    Full Text Available Abstract Background While the larval-juvenile transition (metamorphosis in the spionid polychaete Pseudopolydora vexillosa involves gradual morphological changes and does not require substantial development of juvenile organs, the opposite occurs in the barnacle Balanus amphitrite. We hypothesized that the proteome changes during metamorphosis in the spionids are less drastic than that in the barnacles. To test this, proteomes of pre-competent larvae, competent larvae (ready to metamorphose, and juveniles of P. vexillosa were compared using 2-dimensional gel electrophoresis (2-DE, and they were then compared to those of the barnacle. Results Unlike the significant changes found during barnacle metamorphosis, proteomes of competent P. vexillosa larvae were more similar to those of their juveniles. Pre-competent larvae had significantly fewer protein spots (384 spots, while both competent larvae and juveniles expressed about 660 protein spots each. Proteins up-regulated during competence identified by MALDI-TOF/TOF analysis included a molecular chaperon (calreticulin, a signal transduction regulator (tyrosin activation protein, and a tissue-remodeling enzyme (metallopeptidase. Conclusions This was the first time to study the protein expression patterns during the metamorphosis of a marine polychaete and to compare the proteomes of marine invertebrates that have different levels of morphological changes during metamorphosis. The findings provide promising initial steps towards the development of a proteome database for marine invertebrate metamorphosis, thus deciphering the possible mechanisms underlying larval metamorphosis in non-model marine organisms.

  17. Embryonic and larval development of critically endangered riverine catfish Rita rita

    Directory of Open Access Journals (Sweden)

    Muhammad Fazlul Awal Mollah

    2011-11-01

    Full Text Available The present study was carried out to investigate the embryonic and larval development of freshwater catfish Rita rita. The mature eggs and sperms were collected by using artificial insemination technique and fertilized eggs were incubated in mini circular hatchery with provision of continuously water supply. The fertilized eggs were transparent, demarsal, spherical, non-adhesive and brownish in colour with a diameter ranging between 1.3 to 1.6 mm. First cleavage occurred within 25-30 min post-fertilization at temperature of 28±1°C. Hatching started 22 h post-fertilization and completed within 24 h at the same temperature range. Newly hatched larvae were 2.0 mm in length devoid of mouth and pigmentation and started feeding at 48 to 60 h post-hatching. To date, this is the first time the early embryonic and larval development of freshwater catfish R. rita is described. Thus the findings of the present study provide valuable information that may help establishing the large scale seed production technique of Rita.

  18. Improving Narrative Skills in Young Children with Delayed Language Development

    Science.gov (United States)

    Davies, Peter; Shanks, Becky; Davies, Karen

    2004-01-01

    A substantial number of 5-7 year old children experience delayed language development which threatens their progress in school, although they have not been placed on speech and language therapy caseloads. Children with delayed language development typically have a limited ability to understand and tell stories. Intervention to develop the oral…

  19. Tcmof regulates larval/pupal development and female fecundity in red flour beetle, Tribolium castaneum.

    Science.gov (United States)

    Wang, Yanyun; Li, Chengjun; Sang, Ming; Li, Bin

    2015-02-01

    Males absent on the first (MOF) was originally identified as an essential component of the X chromosome dosage compensation system in Drosophila melanogaster, and is also a member of the MYST family of histone acetyltransferases. MOF has been extensively studied in D. melanogaster and mammals. However, whether MOF is involved in dosage compensation and/or other vital functions for newly emerging model insects such as Tribolium castaneum, is unclear. We cloned the mof from T. castaneum, named Tcmof. Phylogenetic analysis revealed that mof is highly conserved in eukaryotes but lost in birds. qPCR showed that Tcmof was most highly expressed in the early embryo stage and equally expressed in males and females. Treating larvae with ds-Tcmof led 79.1% of the insects to arrest during its eclosion; the remaining insects died either in the larval stage or immediately following eclosion. Treating pupae with the same construct eliminated the fertility of T. castaneum. This effect was rescued by reciprocal crosses with wild-type females, but not males. We infer that the mof gene is essential for larval/pupal development and female fertility in T. castaneum.

  20. Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity.

    Science.gov (United States)

    Chung, J Sook; Maurer, Leah; Bratcher, Meagan; Pitula, Joseph S; Ogburn, Matthew B

    2012-09-03

    Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5' and 3' RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. We report the ontogenetic variation in CasAQP-1 expression during the larval development

  1. Neural development in Eucidaris tribuloides and the evolutionary history of the echinoid larval nervous system.

    Science.gov (United States)

    Bishop, Cory D; MacNeil, Katelyn E A; Patel, Digna; Taylor, Valerie J; Burke, Robert D

    2013-05-01

    The structure and development of the larval nervous systems of all classes of echinoderms have been described and details of embryonic signaling mechanisms patterning neurogenesis have been revealed experimentally in sea urchins. Several features of neuroanatomy and neural development indicate that echinoids are the most derived group. Here we describe the development and organization of the nervous system of a cidaroid, Eucidaris tribuloides. The cidaroids are one of two major clades of echinoids, and are considered to have features of anatomy and development that represent the common ancestor to all echinoids. The embryos of E. tribuloides lack a thickened animal plate and serotonergic neurons arise laterally, associated with the ciliary band. Although lacking a discrete apical organ, plutei have serotonergic neurons associated with the pre-oral ciliary band joined by a few diffusely arranged connecting axons. Chordin and Hnf6, early markers for oral ectoderm and ciliary band, are expressed in similar patterns to euechinoids. However, an animal pole domain marker, Nk2.1, is expressed in a broader region of anterior ectoderm than in euechinoids. Six3, a proneural marker that is restricted to the animal plate of euechinoids, is expressed laterally in the preoral ciliary band at the same location as the serotonergic neurons. We conclude that the organization and development of the larval nervous system of E. tribuloides retains features shared with other echinoderm larvae, but not with euechinoids. These data support a model in which several distinctive features of euechinoid neural organization are derived, having arisen after the divergence of the two clades of echinoids about 265 million years ago. We hypothesize that differences in the developmental mechanisms that restrict neurogenesis to the animal pole forms the basis for the distinctive neuroanatomy of euechinoids.

  2. The presence of predators modifies the larval development of Fasciola hepatica in surviving Lymnaea truncatula.

    Science.gov (United States)

    Rondelaud, D; Vignoles, P; Dreyfuss, G

    2002-06-01

    Experimental infections of Lymnaea truncatula with Fasciola hepatica were performed to study the consequences of the presence of predators (sciomyzid larvae or zonitid snails) on the characteristics of larval F. hepatica development in surviving snails. Controls consisted of infected snails that were not subjected to predators. Compared to controls, the survival rate at day 30 post-exposure, the duration of cercarial shedding, and the number of cercariae shed by surviving snails were significantly lower when predators were present in snail breeding boxes, whatever the type of predator used. In contrast, the prevalences of Fasciola infections in snails, and the length of time between exposure and the onset of cercarial shedding showed no significant variation. The progressive development of a stress reaction in surviving snails against predators during the first 30 days of experimental exposure to F. hepatica would influence snail survival during the cercarial shedding period and, consequently, the number of cercariae shed by the snails.

  3. The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development

    Science.gov (United States)

    De Marco, Rodrigo J.; Groneberg, Antonia H.; Yeh, Chen-Min; Treviño, Mario; Ryu, Soojin

    2014-01-01

    The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging. PMID:25368561

  4. Embryonic, Larval, and Early Juvenile Development of the Tropical Sea Urchin, Salmacis sphaeroides (Echinodermata: Echinoidea

    Directory of Open Access Journals (Sweden)

    M. Aminur Rahman

    2012-01-01

    Full Text Available Salmacis sphaeroides (Linnaeus, 1758 is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10−5 dilution was 96.6±1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell, 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72±4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition.

  5. Proteomic analysis of Oesophagostomum dentatum (Nematoda during larval transition, and the effects of hydrolase inhibitors on development.

    Directory of Open Access Journals (Sweden)

    Martina Ondrovics

    Full Text Available In this study, in vitro drug testing was combined with proteomic and bioinformatic analyses to identify and characterize proteins involved in larval development of Oesophagostomum dentatum, an economically important parasitic nematode. Four hydrolase inhibitors ο-phenanthroline, sodium fluoride, iodoacetamide and 1,2-epoxy-3-(pnitrophenoxy-propane (EPNP significantly inhibited (≥90% larval development. Comparison of the proteomic profiles of the development-inhibited larvae with those of uninhibited control larvae using two-dimensional gel electrophoresis, and subsequent MALDI-TOF mass spectrometric analysis identified a down-regulation of 12 proteins inferred to be involved in various larval developmental processes, including post-embryonic development and growth. Furthermore, three proteins (i.e. intermediate filament protein B, tropomyosin and peptidyl-prolyl cis-trans isomerase inferred to be involved in the moulting process were down-regulated in moulting- and development-inhibited O. dentatum larvae. This first proteomic map of O. dentatum larvae provides insights in the protein profile of larval development in this parasitic nematode, and significantly improves our understanding of the fundamental biology of its development. The results and the approach used might assist in developing new interventions against parasitic nematodes by blocking or disrupting their key biological pathways.

  6. Ocean warming ameliorates the negative effects of ocean acidification on Paracentrotus lividus larval development and settlement.

    Science.gov (United States)

    García, Eliseba; Clemente, Sabrina; Hernández, José Carlos

    2015-09-01

    Ocean warming and acidification both impact marine ecosystems. All organisms have a limited body temperature range, outside of which they become functionally constrained. Beyond the absolute extremes of this range, they cannot survive. It is hypothesized that some stressors can present effects that interact with other environmental variables, such as ocean acidification (OA) that have the potential to narrow the thermal range where marine species are functional. An organism's response to ocean acidification can therefore be highly dependent on thermal conditions. This study evaluated the combined effects of predicted ocean warming conditions and acidification, on survival, development, and settlement, of the sea urchin Paracentrotus lividus. Nine combined treatments of temperature (19.0, 20.5 and 22.5 °C) and pH (8.1, 7.7 and 7.4 units) were carried out. All of the conditions tested were either within the current natural ranges of seawater pH and temperature or are within the ranges that have been predicted for the end of the century, in the sampling region (Canary Islands). Our results indicated that the negative effects of low pH on P. lividus larval development and settlement will be mitigated by a rise in seawater temperature, up to a thermotolerance threshold. Larval development and settlement performance of the sea urchin P. lividus was enhanced by a slight increase in temperature, even under lowered pH conditions. However, the species did show negative responses to the levels of ocean warming and acidification that have been predicted for the turn of the century. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Effects of proteinase inhibitor from Adenanthera pavonina seeds on short- and long term larval development of Aedes aegypti.

    Science.gov (United States)

    Sasaki, Daniele Yumi; Jacobowski, Ana Cristina; de Souza, Antônio Pancrácio; Cardoso, Marlon Henrique; Franco, Octávio Luiz; Macedo, Maria Lígia Rodrigues

    2015-05-01

    Currently, one of the major global public health concerns is related to the transmission of dengue/yellow fever virus by the vector Aedes aegypti. The most abundant digestive enzymes in Ae. aegypti midgut larvae are trypsin and chymotrypsin. Since protease inhibitors have the capacity to bind to and inhibit the action of insect digestive proteinases, we investigated the short- and long-term effects of Adenanthera pavonina seed proteinase inhibitor (ApTI) on Ae. aegypti larvae, as well as a possible mechanism of adaptation. ApTI had a significant effect on Ae. aegypti larvae exposed to a non-lethal concentration of ApTI during short- and long-duration assays, decreasing survival, weight and proteinase activities of midgut extracts of larvae. The zymographic profile of ApTI demonstrated seven bands; three bands apparently have trypsin-like activity. Moreover, the peritrophic membrane was not disrupted. The enzymes of ApTI-fed larvae were found to be sensitive to ApTI and to have a normal feedback mechanism; also, the larval digestive enzymes were not able to degrade the inhibitor. In addition, ApTI delayed larval development time. Histological studies demonstrated a degeneration of the microvilli of the posterior midgut region epithelium cells, hypertrophy of the gastric caeca cells and an augmented ectoperitrophic space in larvae. Moreover, Ae. aegypti larvae were incapable of overcoming the negative effects of ApTI, indicating that this inhibitor might be used as a promising agent against Ae. aegypti. In addition, molecular modeling and molecular docking studies were also performed in order to construct three-dimensional theoretical models for ApTI, trypsin and chymotrypsin from Ae. aegypti, as well as to predict the possible interactions and affinity values for the complexes ApTI/trypsin and ApTI/chymotrypsin. In this context, this study broadens the base of our understanding about the modes of action of proteinase inhibitors in insects, as well as the way insects

  8. Fine-scale temperature fluctuation and modulation of Dirofilaria immitis larval development in Aedes aegypti.

    Science.gov (United States)

    Ledesma, Nicholas; Harrington, Laura

    2015-04-15

    We evaluated degree-day predictions of Dirofilaria immitis development (HDU) under constant and fluctuating temperature treatments of equal average daily temperature. Aedes aegypti mosquitoes were infected with D. immitis microfilariae and parasite development was recorded at set time points in dissected mosquitoes. Time to L3 development in Malpighian tubules and detection in mosquito heads was shorter for larvae experiencing a daily regime of 19±9°C than larvae at constant 19°C; larval development rate in Malpighian tubules was slower in fluctuating regimes maintained above the 14°C developmental threshold than larvae under constant temperatures. We showed that hourly temperature modeling more accurately predicted D. immitis development to infective L3 stage. Development time differed between fluctuating and constant temperature treatments spanning the 14°C development threshold, implicating a physiological basis for these discrepancies. We conclude that average daily temperature models underestimate L3 development-and consequently dog heartworm transmission risk-at colder temperatures, and spatiotemporal models of D. immitis transmission risk should use hourly temperature data when analyzing high daily temperature ranges spanning 14°C. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Fine-scale temperature fluctuation and modulation of Dirofilaria immitis larval development in Aedes aegypti

    Science.gov (United States)

    Ledesma, Nicholas; Harrington, Laura

    2015-01-01

    We evaluated degree-day predictions of Dirofilaria immitis development (HDU) under constant and fluctuating temperature treatments of equal average daily temperature. Aedes aegypti mosquitoes were infected with D. immitis microfilariae and parasite development was recorded at set time points in dissected mosquitoes. Time to L3 development in Malpighian tubules and detection in mosquito heads was shorter for larvae experiencing a daily regime of 19±9°C than larvae at constant 19°C; larval development rate in Malpighian tubules was slower in fluctuating regimes maintained above the 14°C developmental threshold than larvae under constant temperatures. We showed that hourly temperature modeling more accurately predicted D. immitis development to infective L3 stage. Development time differed between fluctuating and constant temperature treatments spanning the 14°C development threshold, implicating a physiological basis for these discrepancies. We conclude that average daily temperature models underestimate L3 development—and consequently dog heartworm transmission risk—at colder temperatures, and spatio-temporal models of D. immitis transmission risk should use hourly temperature data when analyzing high daily temperature ranges spanning 14°C. PMID:25747489

  10. Oviposition and larval development of a stem borer, Eoreuma loftini, on rice and non-crop grass hosts

    Science.gov (United States)

    A greenhouse study compared oviposition preference and larval development duration of a stem borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), on rice, Oryza sativa L. (cv. Cocodrie), and four primary non-crop hosts of Gulf Coast Texas rice agroecosystems. Rice and two perennials, johnsongrass...

  11. GROWTH AND CHANGES IN BIOCHEMICAL COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986

    Science.gov (United States)

    Larval development in Menippe adina was associated with changes in weight and biochemical composition. Larvae of the stone crab, M. adina, were mass-reared under laboratory conditions (28|C; 20o/ooS) from hatching to the megalopal stage. Growth in M. adina is exponential througho...

  12. Regional immune responses with stage-specific antigen recognition profiles develop in lymph nodes of pigs following Ascaris suum larval migration

    DEFF Research Database (Denmark)

    Jungersen, Gregers; Eriksen, Lizzie; Nansen, P.

    2001-01-01

    The early life-cycle of the pig round worm, Ascaris suum, involves well-defined larval development in the liver; lungs and finally the small intestine. Distinct regional immune responses to larval antigens of A. suum were observed in the draining lymph nodes of immunized and challenged pigs during...... larval migration. This was reflected in a transient enlargement of the stimulated lymph nodes, due to increases in numbers of B cells and CD4 T cells, and the production of A. suum-specific antibody by antibody secreting cell (ASC) cultures. Larval antigen recognition pattern of antibodies in serum, bile...

  13. 2D Gel-Based Multiplexed Proteomic Analysis during Larval Development and Metamorphosis of the Biofouling Polychaete Tubeworm Hydroides elegans

    KAUST Repository

    Zhang, Yu

    2010-09-03

    Larval settlement and metamorphosis of a common biofouling polychaete worm, Hydroides elegans, involve remarkable structural and physiological changes during this pelagic to sessile habitat shift. The endogenous protein molecules and post-translational modifications that drive this larval transition process are not only of interest to ecologists but also to the antifouling paint industry, which aims to control the settlement of this biofouling species on man-made structures (e.g., ship hulls). On the basis of our recent proteomic studies, we hypothesize that rapid larval settlement of H. elegans could be mediated through changes in phosphorylation status of proteins rather than extensive de novo synthesis of proteins. To test this hypothesis, 2D gel-based multiplexed proteomics technology was used to monitor the changes in protein expression and phosphorylation status during larval development and metamorphosis of H. elegans. The protein expression profiles of larvae before and after they reached competency to attach and metamorphose were similar in terms of major proteins, but the percentage of phosphorylated proteins increased from 41% to 49% after competency. Notably, both the protein and phosphoprotein profiles of the metamorphosed individuals (adult) were distinctly different from that of the larvae, with only 40% of the proteins phosphorylated in the adult stage. The intensity ratio of all phosphoprotein spots to all total protein spots was also the highest in the competent larval stage. Overall, our results indicated that the level of protein phosphorylation might play a crucial role in the initiation of larval settlement and metamorphosis. © 2010 American Chemical Society.

  14. Xanthophore migration from the dermis to the epidermis and dermal remodeling during Salamandra salamandra salamandra (L.) larval development.

    Science.gov (United States)

    Pederzoli, Aurora; Gambarelli, Andrea; Restani, Cinzia

    2003-02-01

    During larval development of Salamandra salamandra salamandra chromatophores organize to form the definitive pigment pattern constituted by a black background with yellow patches that are characterized by epidermal xanthophores and dermal iridophores. Simultaneously the dermis undergoes remodeling from the larval stage to that typical of the adult. In the present study we ultrastucturally and immunocytochemically examined skin fragments of S. s. salamandra larvae and juveniles in order to investigate the modalities of xanthophore migration and differentiation in the context of dermal remodeling from the larval to adult stage. Semithin and thin sections showed that the dermis in newly born larvae consists of a compact connective tissue (basement lamella), to which fibroblasts and xanthophores adhere, and of a loose deep collagen layer. As larval development proceeds, fibroblasts and xanthophores invade the basement lamella, skin glands develop and the adult dermis forms. At metamorphosis, xanthophores reach the epidermis crossing through the basal lamina. We examined immunocytochemically the expression of signal molecules, such as fibronectin, vitronectin, beta1-integrin, chondroitin sulfate, E-cadherin, N-cadherin and plasminogen activator, which are known to be involved in regulating morphogenetic events. Their role in dermal remodeling and in pigment pattern formation is discussed.

  15. Effect of different diets and rearing tanks on the development and larval survival of Lysmata amboinensis (De Mann, 1888

    Directory of Open Access Journals (Sweden)

    Daniel Marques

    2014-06-01

    Full Text Available The optimization of rearing tanks and identification of rich nutritional diets for the larval development of ornamental decapods are two key factors in defining suitable protocols for larval rearing. The main objective of this study was to evaluate the effect of two rearing tanks (spheroconical and planktonkreisel and three different diets (diet 1: newly hatched Artemia nauplii on a density of 5 nauplii/ml, diet 2: newly hatched Artemia nauplii and harpacticoid copepods on a proportion of 3 artemia nauplii and 2 copepods/ml, Diet 3: Tetraselmis chuii for the first 24h, followed by Artemia nauplii at a density of 5 nauplii/ml on the survival rate and larval development time of Lysmata amboinensis. The results here obtained indicated that the survival rate at 10 days after hatching on kreisel tanks (48.9 ± 3.60% was significantly higher than spheroconical tanks (16.2 ± 2.80% (PTetraselmis chuii was used as a first food (76.7 ± 6.67%. The development time from Zoea I to Zoea IV of L. amboinensis was faster when subject to diet 1 (7.5 ± 0.01 days. In contrast, diet 3 was revealed a longer development period (8.2 ± 0.01 days. The use of copepods diet on the larval rearing of L. amboinensis larvae although not displaying the highest survival, revealed to be extremely promising, needing to adjust the size of the prey throughout the larval development of L. amboinensis.

  16. Evolution and plasticity of anuran larval development in response to desiccation. A comparative analysis.

    Science.gov (United States)

    Richter-Boix, Alex; Tejedo, Miguel; Rezende, Enrico L

    2011-09-01

    Anurans breed in a variety of aquatic habitats with contrasting levels of desiccation risk, which may result in selection for faster development during larval stages. Previous studies suggest that species in ephemeral ponds reduce their developmental times to minimize desiccation risks, although it is not clear how variation in desiccation risk affects developmental strategies in different species. Employing a comparative phylogenetic approach including data from published and unpublished studies encompassing 62 observations across 30 species, we tested if species breeding in ephemeral ponds (High risk) develop faster than those from permanent ponds (Low risk) and/or show increased developmental plasticity in response to drying conditions. Our analyses support shorter developmental times in High risk, primarily by decreasing body mass at metamorphosis. Plasticity in developmental times was small and did not differ between groups. However, accelerated development in High risk species generally resulted in reduced sizes at metamorphosis, while some Low risk species were able compensate this effect by increasing mean growth rates. Taken together, our results suggest that plastic responses in species breeding in ephemeral ponds are constrained by a general trade-off between development and growth rates.

  17. Embryonic and larval development of the suckermouth sailfin catfish Pterygoplichthys pardalis from Marikina River, Philippines

    Directory of Open Access Journals (Sweden)

    Joycelyn Cagatin Jumawan

    2014-05-01

    Full Text Available Background: There is little information about the early development of this invasive fish species in order to understand its early life history and developmental strategies towards invasion. Material and Methods: Female Pterygoplichthys pardalis were induced to spawn using human chorionic gonadotropin (HCG so as to study the developmental stages from fertilization until yolk resorption. Results: The females subjected to a single dose of HCG responded positively to treatment (97% with higher fertilization success (88% compared to the untreated females (21%. Nonetheless, the HCG-induced fertilized eggs had a low hatching success (49%, while from the free-living embryos successfully hatched, a high number (90% survived to become juveniles. Embryonic development in P. pardalis was completed 168 h and 30 min after fertilization, with the total yolk resorption completed on the 8th day post hatching, during which the suckermouth gradually shifted from rostral to ventral position to commence the loricariid algae-scraping feeding mode. Conclusions: Pterygoplichthys pardalis does not undergo a true larval metamorphosis between the free-living embryo and the juvenile stage and a definitive adult phenotype is developed directly. These results provided basic, yet essential information on the early developmental features of this invasive species whose spawning and early developmental strategies were difficult to observe in the field. Implications of some ontogenetic features in this species with regards to invasion are also discussed.

  18. Spawn and larval development of Pleuroploca aurantiaca (Lamarck, 1816 (Gastropoda: Fasciolariidae from Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Carlos A. O. Meirelles

    2005-06-01

    Full Text Available Spawn and larval development stages of Pleuroploca aurantiaca from northeast Brazil are described. The reproductive period lasted from August to December, with a peak in November. Spawn masses were composed of 29 ± 3 vase-shaped capsules which measured 9 ± 1 mm (n = 30 in length and 4.5 ± 0.5 mm (n = 30 in width. The exit plug was located on the apical area and measured 2.5 ± 0.5 mm (n = 30 in diameter. Each capsule had 353 ± 59 (n = 10 eggs that measured 240 ± 1 µm (n = 15 in diameter. On the tenth day, the intracapsular veliger stage was observed. The intracapsular pediveliger stage was observed on the twenty first day, when the individuals had a functional foot and a reduced velum. Hatching occurred on the thirtieth day, when the early juvenile measured 3 to 5 mm in length and there was no remaining velum. Only 1% of the eggs developed to the hatching stage. The rest were nurse eggs used by embryos as a food resource. Pleuroploca aurantiaca has an intracapsular metamorphosis development type.

  19. Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

    Science.gov (United States)

    Du, Rongbin; Wang, Yongqiang; Jiang, Haibin; Liu, Liming; Wang, Maojian; Li, Tianbao; Zhang, Shubao

    2010-01-01

    Broodstock of Verasper moseri (Jordan and Gilbert) aged 3-4 years old were selected, and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions. Fertilized eggs were obtained by artificial fertilization, and the development of embryos, larvae and juveniles was observed continuously. The results showed that the fertilized eggs of V. moseri were spherical, with transparent yolk and homogeneous bioplasm, and had no oil globule inside. The average diameter of the eggs was 1.77±0.02 mm. The eggs of V. moseri were buoyant in water with salinity above 35. The cleavage type was typical discoidal. Young pigment cells appeared when olfactory plates began to form. Hatching occurred at 187 h after fertilization at a water temperature of 8.5°C. The newly hatched larvae, floating on the water surface, were transparent with an average total length of 4.69±0.15 mm. During the cultivation period, when the water temperature was raised from 9 to 14.5°C, 4-day old larvae showed more melanophores on the body surface, making the larvae gray in color. The pectoral fins began to develop, which enabled the larvae to swim horizontally and in a lively manner. On days 7-8, the digestive duct formed. The yolk sac was small and black. The yolk sac was absorbed on day 11. Larvae took food actively, and body length and body height clearly increased. The rudiments of dorsal and anal fin pterygiophores were discernible and caudal fin ray elements formed on day 19. On day 24, the larval notochord flexed upwards, and the rays of unpaired fins began to differentiate. Pigment cells converged on the dorsal and anal fin rays, and the mastoid teeth on the mandible appeared. On day 29, the left eyes of juveniles began to move upwards. Depigmentation began in some juveniles and they became sandy brown in color on day 37. Most juveniles began to settle on the bottom of the tank. The left eyes of juveniles migrated completely to the right

  20. Typical and Delayed Lexical Development in Italian

    Science.gov (United States)

    Rescorla, Leslie; Frigerio, Alessandra; Sali, Maria Enrica; Spataro, Pietro; Longobardi, Emiddia

    2014-01-01

    Purpose: The Language Development Survey (LDS; Rescorla, 1989) was used to compare Italian and English lexical development. The authors addressed the issue of universal versus language-specific aspects of lexical development by testing language, age, and gender effects on vocabulary scores and by comparing vocabulary composition across languages.…

  1. Acidic intracellular pH shift during Caenorhabditis elegans larval development

    Energy Technology Data Exchange (ETDEWEB)

    Wadsworth, W.G.; Riddle, D.L. (Univ. of Missouri, Columbia (USA))

    1988-11-01

    During recovery from the developmentally arrested, nonfeeding dauer stage of the nemotode Caenorhabditis elegans, metabolic activation is accompanied by a decrease in intracellular pH (pH{sub i}). Phosphorus-31 nuclear magnetic resonance ({sup 31}P NMR) analyses of perchloric acid extracts show that inorganic phosphate predominates in dauer larvae, whereas ATP and other high-energy metabolites are abundant within 6 hr after dauer larvae have been placed in food to initiate development. Although metabolic activation has been associated with an alkaline pH{sub i} shift in other organisms, in vivo {sup 31}P NMR analysis of recovering dauer larvae shows a pH{sub i} decrease from {approx} 7.3 to {approx} 6.3 within 3 hr after the animals encounter food. This shift occurs before feeding begins, and it coincides with, or soon follows, the developmental commitment to recover from the dauer stage, suggesting that control of pH{sub i} may be important in the regulation of larval development in nematodes.

  2. Early embryo and larval development of inviable intergeneric hybrids derived from Crassostrea angulata and Saccostrea cucullata

    Science.gov (United States)

    Su, Jiaqi; Wang, Zhaoping; Zhang, Yuehuan; Yan, Xiwu; Li, Qiongzhen; Yu, Ruihai

    2016-06-01

    To detect the intergeneric hybridization between the oyster Crassostrea angulata and Saccostrea cucullata coexisting along the southern coast of China, reciprocal crosses were conducted between the two species. Barriers for sperm recognizing, binding, penetrating the egg, and forming the pronucleus were detected by fluorescence staining. From the results, although fertilization success was observed in hybrid crosses, the overall fertilization rate was lower than that of intraspecific crosses. A large number of hybrid larvae died at 6-8 d after hatching, and those survived could not complete metamorphosis. C. angulata ♀× S. cucullata ♂ larvae had a growth rate similar to that of the maternal species, whereas S. cucullata ♀ × C. angulata ♂ larvae grew the slowest among all crosses. Molecular genetics analysis revealed that hybrid progeny were amphimixis hybrids. This study demonstrated that hybrid embryos generated by crossing C. angulata and S. cucullata could develop normally to the larval state, but could not complete metamorphosis and then develop to the spat stage. Thus, there is a post-reproductive isolation between C. angulata and S. cucullata.

  3. Cholesterol Effect on Survival and Development of Larval Mud Crab Scylla serrata

    Directory of Open Access Journals (Sweden)

    KATSUYUKI HAMASAKI

    2012-03-01

    Full Text Available The effect of cholesterol on the survival and development of larval mud crab Scylla serrata were examined by feeding larvae with Artemia enriched with different level of cholesterol. Artemia enriched with four stated levels of cholesterol i.e., 0, 5, 10, and 20 ul/l (Chol 0, 5, 10, and 20. All treatments were mixed with DHA70G at 25 ul/l. All the oil was adjusted to 100 ul/l by adding the oleic acid. Survival rate, intermolt period, and carapace width at the fisrt crab stage of mud crab larvae fed Chol 0, 5, and 10 were higher compared to that of Chol 20 (P < 0.05. We suggest that free sterol contained in Artemia at 1.37% was harmful to the growth performance of mud crab larvae. This study suggests that mud crab larvae required at least 0.61% cholesterol for maintaining good survival and development and therefore no need to enrich Artemia by cholesterol for the practical purpose.

  4. The development of the digestive tract in larval European catfish (Silurus glanis L.).

    Science.gov (United States)

    Kozarić, Z; Kuzir, S; Petrinec, Z; Gjurcević, E; Bozić, M

    2008-04-01

    The European catfish, Silurus glanis L., has become an important aqua cultural fish in Croatia, and it is cultivated extensively in ponds in polyculture with carps. The development of the digestive tract in S. glanis was studied with the aim of improving intensive fish production. Research was carried out on S. glanis larval stadium from 1- to 19-day post-hatching (DPH). The main histological methods used were: haematoxylin and eosin staining, periodic acid Schiff staining (PAS), Alcian blue (AB) and toluidin blue staining (TB). A yolk sac was present during the first 5 days (1-5-DPH). During the initial 3-DPH period, there was no trace PAS and AB activity in the digestive tract. Differentiation of the digestive tract began at 3- to 5-DPH. The oesophagus was positive for AB at 5-DPH, PAS and TB after 7-DPH. Differentiation of enterocytes began at 5-DPG and the intestines were complete at 11-DPH. Development of liver and pancreas was also studied. The analysis of data obtained in this study suggests that after 5-DPH catfish larvae have morphologically completed digestive tracts.

  5. EFFECTS OF TEMPERATURE AND Ca2+ ON THE LARVAL DEVELOPMENT OF THE DECAPODA CRUSTACEAN: ERIOCHEIR SINENSIS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With increasing demand in China for the mitten crab larvae, understanding its survival mechanism gets more important. This research focused on the effects of temperature and Ca2+ on the larval growth and development. Eriocheir sinensis larvae were reared in laboratory under 21 different combinations of temperature (15, 20, 25℃) and Ca2+ content (120, 130, 140, 150, 160, 170, 180 mg/l) and constant salinity (20) and pH (8). The results suggested that the survival rate increases with temperature and Ca2+ content. These combinations of temperature and Ca2+ content maximized survival rate in our study and it may be the optimum water environmental conditions for culturing the larvae. To predict surviving larvae number under different water environmental conditions, 21 dynamic mathematical models were developed. This for the first time observation of the zoeal Ⅵ larvae of the Changjiang River E. sinensis population showed that they occurred under stressed water environmental conditions: temperature of 15℃ and Ca2+ content of 120,130 mg/l.

  6. Development of a statistically based access delay timeline methodology.

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, W. Gary; Robinson, David Gerald; Wyss, Gregory Dane; Hendrickson, Stacey M. Langfitt

    2013-02-01

    The charter for adversarial delay is to hinder access to critical resources through the use of physical systems increasing an adversarys task time. The traditional method for characterizing access delay has been a simple model focused on accumulating times required to complete each task with little regard to uncertainty, complexity, or decreased efficiency associated with multiple sequential tasks or stress. The delay associated with any given barrier or path is further discounted to worst-case, and often unrealistic, times based on a high-level adversary, resulting in a highly conservative calculation of total delay. This leads to delay systems that require significant funding and personnel resources in order to defend against the assumed threat, which for many sites and applications becomes cost prohibitive. A new methodology has been developed that considers the uncertainties inherent in the problem to develop a realistic timeline distribution for a given adversary path. This new methodology incorporates advanced Bayesian statistical theory and methodologies, taking into account small sample size, expert judgment, human factors and threat uncertainty. The result is an algorithm that can calculate a probability distribution function of delay times directly related to system risk. Through further analysis, the access delay analyst or end user can use the results in making informed decisions while weighing benefits against risks, ultimately resulting in greater system effectiveness with lower cost.

  7. In vitro detection of benzimidazole resistance in Haemonchus contortus: egg hatch test versus larval development test.

    Science.gov (United States)

    Várady, M; Cudeková, P; Corba, J

    2007-10-21

    The present study was designed to compare the egg hatch test (EHT) and the larval development test (LDT) as in vitro tools for detection of benzimidazole (BZ) resistance in Haemonchus contortus, a nematode parasite of small ruminants. Comparisons were made during a course of infection and changes in both EHT and LDT were monitored to measure the correlation between resistance and susceptibility in different parasite stages (eggs and larvae). In addition, mixed doses of known numbers of susceptible and BZ-resistant H. contortus eggs were used to assess the sensitivity of LDT for the detection of low levels of resistance. The degree of resistance for each test was expressed as resistance factor (RF). The LDT showed a greater ability to distinguish between four susceptible and four resistant isolates of H. contortus with higher resistance factors compared to the EHT. For the EHT the RF by using ED(50) criterion ranged from 3.2 to 13.3 and from 7.4 to 25.2 by using LC(99). For LDT the resistant isolates were 4.3-63.1 times more tolerant than the susceptible isolates using the ED(50) criterion and 91.1-1411.0 times more tolerant using the LC(99) criterion. The LDT was also able to clearly indicate the presence of low level (4%) of resistant larvae amongst a susceptible background population.

  8. Bt Maize Seed Mixtures for Helicoverpa zea (Lepidoptera: Noctuidae): Larval Movement, Development, and Survival on Non-transgenic Maize.

    Science.gov (United States)

    Burkness, Eric C; Cira, T M; Moser, S E; Hutchison, W D

    2015-12-01

    In 2012 and 2013, field trials were conducted near Rosemount, MN, to assess the movement and development of Helicoverpa zea (Boddie) larvae on non-Bt refuge corn plants within a seed mixture of non-Bt and Bt corn. The Bt corn hybrid expressed three Bt toxins-Cry1Ab, Cry1F, and Vip3A. As the use of seed mixtures for insect resistance management (IRM) continues to be implemented, it is necessary to further characterize how this IRM approach impacts resistance development in ear-feeding Lepidopteran pests. The potential for Bt pollen movement and cross pollination of the non-Bt ears in a seed mixture may lead to Bt toxin exposure to larvae developing on those refuge ears. Larval movement and development by H. zea, feeding on non-Bt refuge plants adjacent to either transgenic Bt or non-Bt plants, were measured to investigate the potential for unintended Bt exposure. Non-Bt plants were infested with H. zea eggs and subplots were destructively sampled twice per week within each treatment to assess larval development, location, and kernel injury. Results indicate that H. zea larval movement between plants is relatively low, ranging from 2-16% of larvae, and occurs mainly after reaching the second instar. Refuge plants in seed mixtures did not produce equivalent numbers of H. zea larvae, kernel injury, and larval development differed as compared with a pure stand of non-Bt plants. This suggests that there may be costs to larvae developing on refuge plants within seed mixtures and additional studies are warranted to define potential impacts.

  9. Ethanol affects the development of sensory hair cells in larval zebrafish (Danio rerio.

    Directory of Open Access Journals (Sweden)

    Phillip M Uribe

    Full Text Available Children born to mothers with substantial alcohol consumption during pregnancy can present a number of morphological, cognitive, and sensory abnormalities, including hearing deficits, collectively known as fetal alcohol syndrome (FAS. The goal of this study was to determine if the zebrafish lateral line could be used to study sensory hair cell abnormalities caused by exposure to ethanol during embryogenesis. Some lateral line sensory hair cells are present at 2 days post-fertilization (dpf and are functional by 5 dpf. Zebrafish embryos were raised in fish water supplemented with varying concentrations of ethanol (0.75%-1.75% by volume from 2 dpf through 5 dpf. Ethanol treatment during development resulted in many physical abnormalities characteristic of FAS in humans. Also, the number of sensory hair cells decreased as the concentration of ethanol increased in a dose-dependent manner. The dye FM 1-43FX was used to detect the presence of functional mechanotransduction channels. The percentage of FM 1-43-labeled hair cells decreased as the concentration of ethanol increased. Methanol treatment did not affect the development of hair cells. The cell cycle markers proliferating cell nuclear antigen (PCNA and bromodeoxyuridine (BrdU demonstrated that ethanol reduced the number of sensory hair cells, as a consequence of decreased cellular proliferation. There was also a significant increase in the rate of apoptosis, as determined by TUNEL-labeling, in neuromasts following ethanol treatment during larval development. Therefore, zebrafish are a useful animal model to study the effects of hair cell developmental disorders associated with FAS.

  10. Evolution of OTP-independent larval skeleton patterning in the direct-developing sea urchin, Heliocidaris erythrogramma.

    Science.gov (United States)

    Zhou, Na; Wilson, Keen A; Andrews, Mary E; Kauffman, Jeffery S; Raff, Rudolf A

    2003-12-15

    Heliocidaris erythrogramma is a direct-developing sea urchin that has evolved a modified ontogeny, a reduced larval skeleton, and accelerated development of the adult skeleton. The Orthopedia gene (Otp) encodes a homeodomain transcription factor crucial in patterning the larval skeleton of indirect-developing sea urchins. We compare the role of Otp in larvae of the indirect-developing sea urchin Heliocidaris tuberculata and its direct-developing congener H. erythrogramma. Otp is a single-copy gene with an identical protein sequence in these species. Expression of Otp is initiated by the late gastrula, initially in two cells of the oral ectoderm in H. tuberculata. These cells are restricted to oral ectoderm and exhibit left-right symmetry. There are about 266 copies of Otp mRNA per Otp- expressing cell in H. tuberculata. We tested OTP function in H. tuberculata and H. erythrogramma embryos by microinjection of Otp mRNA. Mis-expression of Otp mRNA in H. tuberculata radialized the embryos and caused defects during larval skeletogenesis. Mis-expression of Otp mRNA in H. erythrogramma embryos did not affect skeleton formation. This is consistent with the observation by in situ hybridization of no concentration of Otp transcript in any particular cells or region of the H. erythrogramma larva, and measurement of a level of less than one copy of endogenous Otp mRNA per cell in H. erythrogramma. OTP plays an important role in patterning the larval skeleton of H. tuberculata, but this role apparently has been lost in the evolution of the H. erythrogramma larva, and replaced by a new patterning mechanism.

  11. Effects of larval rearing temperature on immature development and West Nile virus vector competence of Culex tarsalis

    Directory of Open Access Journals (Sweden)

    Dodson Brittany L

    2012-09-01

    Full Text Available Abstract Background Temperature is known to induce changes in mosquito physiology, development, ecology, and in some species, vector competence for arboviruses. Since colonized mosquitoes are reared under laboratory conditions that can be significantly different from their field counterparts, laboratory vector competence experiments may not accurately reflect natural vector-virus interactions. Methods We evaluated the effects of larval rearing temperature on immature development parameters and vector competence of two Culex tarsalis strains for West Nile virus (WNV. Results Rearing temperature had a significant effect on mosquito developmental parameters, including shorter time to pupation and emergence and smaller female body size as temperature increased. However, infection, dissemination, and transmission rates for WNV at 5, 7, and 14 days post infectious feeding were not consistently affected. Conclusions These results suggest that varying constant larval rearing temperature does not significantly affect laboratory estimates of vector competence for WNV in Culex tarsalis mosquitoes.

  12. Larval development of Austinixa bragantina (Crustacea: Brachyura: Pinnotheridae reared in the laboratory

    Directory of Open Access Journals (Sweden)

    Jô de Farias Lima

    2009-03-01

    Full Text Available The zoeal and megalopal stages of Austinixa bragantina Coelho, 2005, a small pinnotherid crab found in association with ghost shrimps Callichirus major (Say, 1818 and Lepidophthalmus siriboia Felder & Rodrigues, 1993 in the northeastern region of the state of Pará, Brazil, were reared in the laboratory from hatching to the megalopal stage. The duration of the larval period from hatching to megalopa was 28 days and the mean of duration for each larval stage was 6, 5, 5, 6, and 6 days, respectively. In the present study, the zoeal and megalopal stages are described and illustrated in detail.

  13. Storm drains as larval development and adult resting sites for Aedes aegypti and Aedes albopictus in Salvador, Brazil

    OpenAIRE

    Paploski, Igor Adolfo Dexheimer; Moreno S Rodrigues; Mugabe, Vánio André; Kikuti,Mariana; Tavares, Aline S.; Reis, Mitermayer Galvão; Kitron, Uriel; Ribeiro, Guilherme Sousa

    2016-01-01

    Background Dengue (DENV), Chikungunya (CHIKV), Zika (ZIKV), as well as yellow fever (YFV) viruses are transmitted to humans by Aedes spp. females. In Salvador, the largest urban center in north-eastern Brazil, the four DENV types have been circulating, and more recently, CHIKV and ZIKV have also become common. We studied the role of storm drains as Aedes larval development and adult resting sites in four neighbourhoods of Salvador, representing different socioeconomic, infrastructure and topo...

  14. Reproduction and development in Halocaridina rubra Holthuis, 1963 (Crustacea: Atyidae) clarifies larval ecology in the Hawaiian anchialine ecosystem.

    Science.gov (United States)

    Havird, Justin C; Vaught, Rebecca C; Weese, David A; Santos, Scott R

    2015-10-01

    Larvae in aquatic habitats often develop in environments different from those they inhabit as adults. Shrimp in the Atyidae exemplify this trend, as larvae of many species require salt or brackish water for development, while adults are freshwater-adapted. An exception within the Atyidae family is the "anchialine clade," which are euryhaline as adults and endemic to habitats with subterranean fresh and marine water influences. Although the Hawaiian anchialine atyid Halocaridina rubra is a strong osmoregulator, its larvae have never been observed in nature. Moreover, larval development in anchialine species is poorly studied. Here, reproductive trends in laboratory colonies over a 5-y period are presented from seven genetic lineages and one mixed population of H. rubra; larval survivorship under varying salinities is also discussed. The presence and number of larvae differed significantly among lineages, with the mixed population being the most prolific. Statistical differences in reproduction attributable to seasonality also were identified. Larval survivorship was lowest (12% settlement rate) at a salinity approaching fresh water and significantly higher in brackish and seawater (88% and 72%, respectively). Correlated with this finding, identifiable gills capable of ion transport did not develop until metamorphosis into juveniles. Thus, early life stages of H. rubra are apparently excluded from surface waters, which are characterized by lower and fluctuating salinities. Instead, these stages are restricted to the subterranean (where there is higher and more stable salinity) portion of Hawaii's anchialine habitats due to their inability to tolerate low salinities. Taken together, these data contribute to the understudied area of larval ecology in the anchialine ecosystem. © 2015 Marine Biological Laboratory.

  15. Foliage maturity of Quercus ilex affects the larval development of a Croatian coastal population of Lymantria dispar (Lepidoptera: Erebidae

    Directory of Open Access Journals (Sweden)

    Lukić Ivan

    2017-02-01

    Full Text Available Gypsy moth (Lymantria dispar is one of the most important forest pests in the world. Numerous previous studies focused only on different host tree species, but small number of them on foliage age. Since recent genetic analyses showed that there are significant differences between Croatian continental and coastal population we investigated coastal population since there was no previous research. For this research juvenile and mature foliage of Holm oak (Quercus ilex was used. Larval development was investigated in two laboratory experiments. One experiment involved rearing trials consisting of 50 individual larvae per treatment while a parallel experiment investigated gregarious feeding conditions using 120 larvae in a rearing treatment. Larval mortality was lower and development time shorter for individuals reared on juvenile foliage. High pupation success in both the individual and group rearing experiment for larvae reared on juvenile foliage was also observed. To conclude, our results showed high mortality, poor larval development and low pupation success in larvae reared on mature foliage. This research is significant because in the aspect of ongoing climate changes there is a possibility that gypsy moth will move to the north and shift its distribution by expanding into new climatic area.

  16. Impact of ocean warming and ocean acidification on larval development and calcification in the sea urchin Tripneustes gratilla.

    Directory of Open Access Journals (Sweden)

    Hannah Sheppard Brennand

    Full Text Available BACKGROUND: As the oceans simultaneously warm, acidify and increase in P(CO2, prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming. METHODOLOGY/PRINCIPAL FINDINGS: We examined the interactive effects of near-future ocean warming and increased acidification/P(CO2 on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/P(CO2 treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/P(CO2 and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3 degrees C stimulated growth, producing significantly bigger larvae across all pH/P(CO2 treatments up to a thermal threshold (+6 degrees C. Increased acidity (-0.3-0.5 pH units and hypercapnia significantly reduced larval calcification. A +3 degrees C warming diminished the negative effects of acidification and hypercapnia on larval growth. CONCLUSIONS AND SIGNIFICANCE: This study of the effects of ocean warming and CO(2 driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high P(CO2 ocean would likely impair their performance with negative consequent effects for benthic adult populations.

  17. Development of the larval amphibian growth and development assay: Effects of benzophenone-2 exposure in Xenopus laevis from embryo to juvenile

    Science.gov (United States)

    The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized chemical testing guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan’s Ministry of Environment to support risk assessment. The assay is employed as a ...

  18. Efficacy and longevity of the newly developed catnip oil microcapsules against stable fly oviposition larval growth

    Science.gov (United States)

    The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is one of the most important pests of cattle and costs U.S. cattle producers billions of dollars in losses annually. In this study, the efficacy of catnip oil encapsulated in gelatin in oviposition deterrence and larval growth inhibition in st...

  19. Elevated copper levels during larval development cause altered locomotor behavior in the adult carabid beetle Pterostichus cupreus L. (Coleoptera: Carbidae)

    DEFF Research Database (Denmark)

    Bayley, M; Baatrup, E; Heimbach, U

    1995-01-01

    It is generally believed that copper causes changes in carabid communities indirectly by reducing food availability, because these animals are frequently found to have only slightly elevated metal contents even close to pollution sources. Using computer-centered video tracking, the locomotor...... behavior of adult Pterostichus cupreus carabid beetles was quantified after being raised on copper-contaminated food and soil during larval development. Copper was found to have an acute toxic effect measured in larval mortality, to cause a slight increase in the developmental period of males......, but not to effect the emergence weights of adults of either sex. This toxic effect on the larvae was preserved through pupation to the surviving adults, which were normal in size and appearance, but displayed a dramatically depressed locomotor behavior. Copper analysis of these adults revealed that copper levels...

  20. Infant overweight is associated with delayed motor development

    Science.gov (United States)

    Slining, Meghan; Adair, Linda S.; Goldman, Barbara Davis; Borja, Judith B.; Bentley, Margaret

    2012-01-01

    Objective To examine how infant overweight and high subcutaneous fat relate to infant motor development. Study design Participants are from the Infant Care, Feeding, and Risk of Obesity Project, a prospective, longitudinal study of low-income African American mother-infant dyads assessed from 3 -18 months of age (836 observations on 217 infants). Exposures were overweight (weight-for-length z-score ≥90th percentile of 2000 CDC/NCHS growth reference) and high subcutaneous fat (sum of three skinfold measurements >90th percentile of our sample). Motor development was assessed using Bayley Scales of Infant Development-II. Developmental delay was characterized as a standardized Psychomotor Development Index score <85. Longitudinal models estimated developmental outcomes as functions of time-varying overweight and subcutaneous fat, controlling for age and sex. Alternate models tested concurrent and lagged relationships (prior weight or subcutaneous fat predicting current motor development). Results Motor delay was 1.80 times as likely in overweight compared with non-overweight infants (95% CI:1.09, 2.97), and 2.32 times as likely in infants with high subcutaneous fat compared with lower subcutaneous fat (95% CI:1.26, 4.29). High subcutaneous fat was also associated with delay in subsequent motor development (OR=2.27, 95% CI:1.08, 4.76). Conclusions Pediatric overweight and high subcutaneous fat are associated with delayed infant motor development. PMID:20227724

  1. The wings of Bombyx mori develop from larval discs exhibiting an early differentiated state: a preliminary report

    Indian Academy of Sciences (India)

    Madhuri Kango-Singh; Amit Singh; K P Gopinathan

    2001-06-01

    Lepidopteran insects present a complex organization of appendages which develop by various mechanisms. In the mulberry silkworm, Bombyx mori a pair of meso- and meta-thoracic discs located on either side in the larvae gives rise to the corresponding fore- and hind-wings of the adult. These discs do not experience massive cell rearrangements during metamorphosis and display the adult wing vein pattern. We have analysed wing development in B. mori by two approaches, viz., expression of patterning genes in larval wing discs, and regulatory capacities of larval discs following explantation or perturbation. Expression of Nubbin is seen all over the presumptive wing blade domains unlike in Drosophila, where it is confined to the hinge and the wing pouch. Excision of meso- and meta-thoracic discs during the larval stages resulted in emergence of adult moths lacking the corresponding wings without any loss of thoracic tissues suggesting independent origin of wing and thoracic primordia. The expression of wingless and distal-less along the dorsal/ventral margin in wing discs correlated well with their expression profile in adult Drosophila wings. Partially excised wing discs did not show in situ regeneration or duplication suggesting their early differentiation. The presence of adult wing vein patterns discernible in larval wing discs and the patterns of marker gene expression as well as the inability of these discs to regulate growth suggested that wing differentiation is achieved early in B. mori. The timings of morphogenetic events are different and the wing discs behave like presumptive wing buds opening out as wing blades in B. mori unlike evagination of only the pouch region as wing blades seen in Drosophila.

  2. Desenvolvimento de Chrysoperla externa alimentada na fase larval com ovos de Bonagota cranaodes Development of Chrysoperla externa fed in the larval stage with eggs of Bonagota cranaodes

    Directory of Open Access Journals (Sweden)

    Ana Lúcia de Paula Ribeiro

    2011-09-01

    Full Text Available Este trabalho teve por finalidade realizar estudos biológicos da espécie de crisopídeo de maior ocorrência nos agroecossistemas brasileiros, Chrysoperla externa, a fim de viabilizar a criação desta em condições de laboratório. O trabalho foi desenvolvido no Laboratório de Entomologia da Universidade Federal de Santa Maria, onde foi estudada a biologia das fases imatura e adulta de C. externa, alimentando suas larvas com ovos de Bonagota cranaodes e os adultos com dieta artificial a base de lêvedo de cerveja e mel na proporção de 1:1. O período embrionário foi determinado utilizando cápsulas de gelatina e tubos de vidro de 2,5x8,5cm e os insetos adultos foram criados em gaiolas de tubo de PVC com 10,0 cm de diâmetro e 23,0cm de comprimento em temperatura de 25±2°C e 70±10% de umidade relativa e fotofase de 14 horas. De acordo com os resultados obtidos, o período embrionário foi de 4,0 dias, com viabilidade de 89,2%. Para a fase larval, foi determinada uma duração de 13,1 dias, sendo a duração média para o 1°, 2° e 3° ínstares de 3,7; 4,9; e 4,5 dias, respectivamente. O período médio de pré-pupa e pupa foi de 1,4 e 9,3 dias, respectivamente, perfazendo um ciclo de desenvolvimento médio de 27,8 dias. As medidas da largura da cápsula cefálica mostraram que a regra de Dyar aplica-se nesse caso. Larvas de Chrysoperla externa podem ser criadas em ovos de Bonagota cranaodes em condições de laboratório.The paper aimed to conduct biological studies of the chrysopidae species most frequent in the Brazilian agroecosystems, Chrysoperla externa, in order to raise this species under laboratory conditions. The research was developed at the Entomology Laboratory of the Federal University of Santa Maria, where biological studies of immature and adult stages of C. externa were performed, feeding its larva with eggs of Bonagota cranaotes and adults with an artificial diet based on beer yeast and honey, in the 1:1 proportion

  3. Effect of CO2-related acidification on aspects of the larval development of the European lobster, Homarus gammarus (L.

    Directory of Open Access Journals (Sweden)

    D. Boothroyd

    2009-08-01

    Full Text Available Oceanic uptake of anthropogenic CO2 results in a reduction in pH termed "Ocean Acidification" (OA. Comparatively little attention has been given to the effect of OA on the early life history stages of marine animals. Consequently, we investigated the effect of culture in CO2-acidified sea water (approx. 1200 ppm, i.e. average values predicted using IPCC 2007 A1F1 emissions scenarios for year 2100 on early larval stages of an economically important crustacean, the European lobster Homarus gammarus. Culture in CO2-acidified sea water did not significantly affect carapace length of H. gammarus. However, there was a reduction in carapace mass during the final stage of larval development in CO2-acidified sea water. This co-occurred with a reduction in exoskeletal mineral (calcium and magnesium content of the carapace. As the control and high CO2 treatments were not undersaturated with respect to any of the calcium carbonate polymorphs measured, the physiological alterations we record are most likely the result of acidosis or hypercapnia interfering with normal homeostatic function, and not a direct impact on the carbonate supply-side of calcification per se. Thus despite there being no observed effect on survival, carapace length, or zoeal progression, OA related (indirect disruption of calcification and carapace mass might still adversely affect the competitive fitness and recruitment success of larval lobsters with serious consequences for population dynamics and marine ecosystem function.

  4. Strongyloides stercoralis age-1: a potential regulator of infective larval development in a parasitic nematode.

    Science.gov (United States)

    Stoltzfus, Jonathan D; Massey, Holman C; Nolan, Thomas J; Griffith, Sandra D; Lok, James B

    2012-01-01

    Infective third-stage larvae (L3i) of the human parasite Strongyloides stercoralis share many morphological, developmental, and behavioral attributes with Caenorhabditis elegans dauer larvae. The 'dauer hypothesis' predicts that the same molecular genetic mechanisms control both dauer larval development in C. elegans and L3i morphogenesis in S. stercoralis. In C. elegans, the phosphatidylinositol-3 (PI3) kinase catalytic subunit AGE-1 functions in the insulin/IGF-1 signaling (IIS) pathway to regulate formation of dauer larvae. Here we identify and characterize Ss-age-1, the S. stercoralis homolog of the gene encoding C. elegans AGE-1. Our analysis of the Ss-age-1 genomic region revealed three exons encoding a predicted protein of 1,209 amino acids, which clustered with C. elegans AGE-1 in phylogenetic analysis. We examined temporal patterns of expression in the S. stercoralis life cycle by reverse transcription quantitative PCR and observed low levels of Ss-age-1 transcripts in all stages. To compare anatomical patterns of expression between the two species, we used Ss-age-1 or Ce-age-1 promoter::enhanced green fluorescent protein reporter constructs expressed in transgenic animals for each species. We observed conservation of expression in amphidial neurons, which play a critical role in developmental regulation of both dauer larvae and L3i. Application of the PI3 kinase inhibitor LY294002 suppressed L3i in vitro activation in a dose-dependent fashion, with 100 µM resulting in a 90% decrease (odds ratio: 0.10, 95% confidence interval: 0.08-0.13) in the odds of resumption of feeding for treated L3i in comparison to the control. Together, these data support the hypothesis that Ss-age-1 regulates the development of S. stercoralis L3i via an IIS pathway in a manner similar to that observed in C. elegans dauer larvae. Understanding the mechanisms by which infective larvae are formed and activated may lead to novel control measures and treatments for strongyloidiasis

  5. Developing methods based on light sheet fluorescence microscopy for biophysical investigations of larval zebrafish

    Science.gov (United States)

    Taormina, Michael J.

    Adapting the tools of optical microscopy to the large-scale dynamic systems encountered in the development of multicellular organisms provides a path toward understanding the physical processes necessary for complex life to form and function. Obtaining quantitatively meaningful results from such systems has been challenging due to difficulty spanning the spatial and temporal scales representative of the whole, while also observing the many individual members from which complex and collective behavior emerges. A three-dimensional imaging technique known as light sheet fluorescence microscopy provides a number of significant benefits for surmounting these challenges and studying developmental systems. A thin plane of fluorescence excitation light is produced such that it coincides with the focal plane of an imaging system, providing rapid acquisition of optically sectioned images that can be used to construct a three-dimensional rendition of a sample. I discuss the implementation of this technique for use in larva of the model vertebrate Danio rerio (zebrafish). The nature of light sheet imaging makes it especially well suited to the study of large systems while maintaining good spatial resolution and minimizing damage to the specimen from excessive exposure to excitation light. I show the results from a comparative study that demonstrates the ability to image certain developmental processes non-destructively, while in contrast confocal microscopy results in abnormal growth due to phototoxicity. I develop the application of light sheet microscopy to the study of a previously inaccessible system: the bacterial colonization of a host organism. Using the technique, we are able to obtain a survey of the intestinal tract of a larval zebrafish and observe the location of microbes as they grow and establish a stable population in an initially germ free fish. Finally, I describe a new technique to measure the fluid viscosity of this intestinal environment in vivo using

  6. Larval development, sensory mechanisms and physiological adaptions in acorn barnacles with special reference to Balanus amphitrite

    Digital Repository Service at National Institute of Oceanography (India)

    Anil, A.C.; Khandeparker, L.; Desai, D.V.; Baragi, L.V.; Gaonkar, C.

    for longer duration, hence a greater dispersal potential. In planktotrophic forms, planktonic period and attainment of a competence stage is variable. In the absence of cues, the capacity to maintain that larval state decreases with time, often leading...), although data suggest that cue specificity in B. amphitrite is rather poor (Bishop et al., 2006a). Most planktotrophic larvae become competent to metamorphose only after spending some time in the plankton (Bishop et al., 2006b). The definition...

  7. Exposure to domoic acid affects larval development of king scallop Pecten maximus (Linnaeus, 1758).

    Science.gov (United States)

    Liu, Hui; Kelly, Maeve S; Campbell, Dirk A; Dong, Shuang Lin; Zhu, Jian Xin; Wang, Su Feng

    2007-02-28

    Domoic acid (DA) is a highly toxic phycotoxin produced by bloom forming marine diatoms Pseudo-nitzschia spp. Bivalves can accumulate this toxin to a high level through their feeding activities, and thus illness or death in can occur in consumers of bivalves. In this study, king scallop, Pecten maximus, larvae were exposed to dissolved domoic acid (DA) for 25d, and the toxin accumulation and effects of harbouring this toxin were investigated. Scallop larvae incorporated DA continuously during the larval culture period and accumulated a maximum DA level of 5.21pgind(-1) when exposed to a solution of 50ngml(-1) dissolved DA. As a result of the DA treatment, larval growth, measured in terms of shell length and the appearance of the eye-spot, and larval survival were significantly compromised. This is the first study on DA incorporation dynamics in P. maximus larvae, signifying the potential of using shellfish larvae for the study on mechanisms of phycotoxin accumulation. The negative effect of DA exposure suggests that this toxin could possibly influence natural recruitment in P. maximus, and it may be necessary to protect hatchery-cultured scallop larvae from DA during toxic Pseudo-nitzschia blooms.

  8. Phosphoproteome analysis during larval development and metamorphosis in the spionid polychaete Pseudopolydora vexillosa

    KAUST Repository

    Chandramouli, Kondethimmanahalli

    2011-05-25

    Background: The metamorphosis of the spionid polychaete Pseudopolydora vexillosa includes spontaneous settlement onto soft-bottom habitats and morphogenesis that can be completed in a very short time. A previous study on the total changes to the proteome during the various developmental stages of P. vexillosa suggested that little or no de novo protein synthesis occurs during metamorphosis. In this study, we used multicolor fluorescence detection of proteins in 2-D gels for differential analysis of proteins and phosphoproteins to reveal the dynamics of post-translational modification proteins in this species. A combination of affinity chromatography, 2D-PAGE, and mass spectrometry was used to identify the phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles. Results: We reproducibly detected 210, 492, and 172 phosphoproteins in pre-competent larvae, competent larvae, and newly metamorphosed juveniles, respectively. The highest percentage of phosphorylation was observed during the competent larval stage. About 64 stage-specific phosphoprotein spots were detected in the competent stage, and 32 phosphoproteins were found to be significantly differentially expressed in the three stages. We identified 38 phosphoproteins, 10 of which were differentially expressed during metamorphosis. These phosphoproteins belonged to six categories of biological processes: (1) development, (2) cell differentiation and integrity, (3) transcription and translation, (4) metabolism, (5) protein-protein interaction and proteolysis, and (6) receptors and enzymes. Conclusion: This is the first study to report changes in phosphoprotein expression patterns during the metamorphosis of the marine polychaete P. vexillosa. The higher degree of phosphorylation during the process of attaining competence to settle and metamorphose may be due to fast morphological transitions regulated by various mechanisms. Our data are consistent with previous studies showing a

  9. The Impact of Seawater Saturation State on Early Skeletal Development in Larval Corals: Insights into Scleractinian Biomineralization

    Science.gov (United States)

    Cohen, A. L.; McCorkle, D. C.; de Putron, S.

    2007-12-01

    contrast to the fine, closed, densely packed spherulitic bundles accreted in the control system, larvae in the lower Omega treatments produced a disorganized conglomerate of large, highly faceted crystals, consistent with slow growth under low saturation state conditions. Our results suggest that the coral calcification response to changes in seawater saturation state is linked to a physiological limitation on the organism's ability to elevate the saturation state of seawater within the calcifying space. Further, our data indicate that ocean acidification due to fossil fuel CO2 emissions will likely have a strong negative effect on the recruitment and early skeletal development of larval corals over the next several decades.

  10. The larval development of Pilumnoides hassleri (Decapoda: Brachyura: Pilumnoididae reared in the laboratory, with a review of pilumnoidid systematics using larval characters

    Directory of Open Access Journals (Sweden)

    Tomás A. Luppi

    2010-03-01

    Full Text Available The genus Pilumnoides is an interesting taxon because its systematic position, based on adult characters, remains unclear. These xanthoid crabs have been related to the Carpiliidae, Goneplacidae and Eriphioidea. P. hassleri A. Milne Edwards, 1880 lives in Brazilian, Uruguayan and Argentinian coasts as far south as the Magellan Strait (southwestern Atlantic. Larvae of P. hassleri from females collected in the harbour of Mar del Plata were reared in the laboratory from zoea I to megalopa and the first larval stage, and described. The species passed through 5 zoeal stages and a megalopa. Larval characters were compared with the previous description of larvae from the southeastern Pacific species P. perlatus and with species of Carpilius, Goneplax and Eriphia in order to review the relationships between these taxa.

  11. Aquatic microfauna alter larval food resources and affect development and biomass of West Nile and Saint Louis encephalitis vector Culex nigripalpus (Diptera: Culicidae).

    Science.gov (United States)

    Duguma, Dagne; Kaufman, Michael G; Simas Domingos, Arthur B

    2017-05-01

    Ciliate protists and rotifers are ubiquitous in aquatic habitats and can comprise a significant portion of the microbial food resources available to larval mosquitoes, often showing substantial declines in abundance in the presence of mosquito larvae. This top-down regulation of protists is reported to be strong for mosquitoes inhabiting small aquatic containers such as pitcher plants or tree holes, but the nature of these interactions with larval mosquitoes developing in other aquatic habitats is poorly understood. We examined the effects of these two microbial groups on lower trophic level microbial food resources, such as bacteria, small flagellates, and organic particles, in the water column, and on Culex larval development and adult production. In three independent laboratory experiments using two microeukaryote species (one ciliate protist and one rotifer) acquired from field larval mosquito habitats and cultured in the laboratory, we determined the effects of Culex nigripalpus larval grazing on water column microbial dynamics, while simultaneously monitoring larval growth and development. The results revealed previously unknown interactions that were different from the top-down regulation of microbial groups by mosquito larvae in other systems. Both ciliates and rotifers, singly or in combination, altered other microbial populations and inhibited mosquito growth. It is likely that these microeukaryotes, instead of serving as food resources, competed with early instar mosquito larvae for microbes such as small flagellates and bacteria in a density-dependent manner. These findings help our understanding of the basic larval biology of Culex mosquitoes, variation in mosquito production among various larval habitats, and may have implications for existing vector control strategies and for developing novel microbial-based control methods.

  12. Delays in clinical development of neurological drugs in Japan.

    Science.gov (United States)

    Ikeda, Masayuki

    2017-06-28

    The delays in the approval and development of neurological drugs between Japan and other countries have been a major issue for patients with neurological diseases. The objective of this study was to analyze factors contributing to the delay in the launching of neurological drugs in Japan. We analyzed data from Japan and the US for the approval of 42 neurological drugs, all of which were approved earlier in the US than in Japan, and examined the potential factors that may cause the delay of their launch. Introductions of the 42 drugs in Japan occurred at a median of 87 months after introductions in the US. The mean review time of new drug applications for the 20 drugs introduced in Japan in January 2011 or later (15 months) was significantly shorter than that for the other 22 drugs introduced in Japan in December 2010 or earlier (24 months). The lag in the Japan's review time behind the US could not explain the approval delays. In the 31 of the 42 drugs, the application data package included overseas data. The mean review time of these 31 drugs (17 months) was significantly shorter than that of the other 11 drugs without overseas data (26 months). The mean approval lag behind the US of the 31 drugs (78 months) was also significantly shorter than that of the other 11 drugs (134 months). These results show that several important reforms in the Japanese drug development and approval system (e.g., inclusion of global clinical trial data) have reduced the delays in the clinical development of neurological drugs.

  13. Testing the effect of dietary carotenoids on larval survival, growth and development in the critically endangered southern corroboree frog.

    Science.gov (United States)

    Byrne, Phillip G; Silla, Aimee J

    2017-03-01

    The success of captive breeding programs (CBPs) for threatened species is often limited due to a lack of knowledge of the nutritional conditions required for optimal growth and survival. Carotenoids are powerful antioxidants known to accelerate vertebrate growth and reduce mortality. However, the effect of carotenoids on amphibian life-history traits remains poorly understood. The aim of our study was to use a manipulative laboratory experiment to test the effect of dietary-carotenoid supplementation during the larval life stage on the survival, growth and development of the critically endangered southern corroboree frog (Pseudophryne corroboree). Larvae were fed either a carotenoid supplemented diet or an unsupplemented diet and the survival, growth and development of individuals was monitored and compared. There was no significant effect of dietary treatment on larval survival, growth rate, time taken to reach metamorphosis, or body size at metamorphosis. Our findings provide no evidence that carotenoid supplementation during the larval life stage improves the growth and development of southern corroboree frogs. However, because the carotenoid dose used in our study did not have any detrimental effects on P. corroboree larvae, but has previously been shown to improve adult coloration, immunity, and exercise performance, carotenoid supplementation should be considered when evaluating the nutritional requirements of P. corroboree in captivity. Carotenoid supplementation studies are now required for a diversity of anuran species to determine the effects of carotenoids on amphibian survival, growth and development. Understanding the effects of dietary carotenoids on different life-history traits may assist with amphibian captive breeding and conservation. © 2017 Wiley Periodicals, Inc.

  14. Characterization of bacterial communities associating with larval development of Yesso Scallop ( Patinopecten yessoensisis Jay, 1857) by high-throughput sequencing

    Science.gov (United States)

    Sun, Xueying; Liu, Jichen; Li, Ming; Zhao, Xuewei; Liang, Jun; Sun, Pihai; Ma, Yuexin

    2016-12-01

    Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop ( Patinopecten yessoensisis Jay, 1857) larval development stages. The aim of this study was to characterize and compare the bacterial communities associating with Yesso scallop larval development at fertilized egg S1, trochophora S2, D-shaped larvae S3, umbo larvae S4, and juvenile scallop S5 stages by Illumina high-throughput sequencing. Genomic DNA was extracted from the larvae and their associating bactera, and a gene segment covering V3-V4 region of 16S rRNA gene was amplified and sequenced using an Illumina Miseq sequencer. Overall, 106760 qualified sequences with an average length of 449 bp were obtained. Sequences were compared with those retrieved from 16S rRNA gene databases, and 4 phyla, 7 classes, 15 orders, 21 families, 31 genera were identified. Proteobacteria was predominant phylum, accounting for more than 99%, at all 5 larval development stages. At genus level, Pseudomonas was dominant at stages S1 (80.60%), S2 (87.77%) and S5 (68.71%), followed by Photobacterium (17.06%) and Aeromonas (1.64%) at stage S1, Serratia (6.94%), Stenotrophomonas (3.08%) and Acinetobacter (1.2%) at stage S2, Shewanella (25.95%) and Pseudoalteromonas (4.57%) at stage S5. Moreover, genus Pseudoalteromonas became dominant at stages S3 (44.85%) and S4 (56.02%), followed by Photobacterium (29.82%), Pseudomonas (11.86%), Aliivibrio (8.60%) and Shewanella (3.39%) at stage S3, Pseudomonas (18.16%), Aliivibrio (14.29%), Shewanella (4.11%), Psychromonas (4.04%) and Psychrobacter (1.81%) at stage S4. From the results, we concluded that the bacterial community changed significantly at different development stages of Yesso Scallop larvae.

  15. Stage-Specific Changes in Physiological and Life-History Responses to Elevated Temperature and Pco2 during the Larval Development of the European Lobster Homarus gammarus (L.).

    Science.gov (United States)

    Small, Daniel P; Calosi, Piero; Boothroyd, Dominic; Widdicombe, Steve; Spicer, John I

    2015-01-01

    An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C∶N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment.

  16. Effects of sub-lethal teratogen exposure during larval development on egg laying and egg quality in adult Caenorhabditis elegans

    Science.gov (United States)

    Killeen, Alexis; Marin de Evsikova, Caralina

    2016-01-01

    Background: Acute high dose exposure to teratogenic chemicals alters the proper development of an embryo leading to infertility, impaired fecundity, and few viable offspring. However, chronic exposure to sub-toxic doses of teratogens during early development may also have long-term impacts on egg quality and embryo viability. Methods: To test the hypothesis that low dose exposure during early development can impact long-term reproductive health, Caenorhabditis elegans larvae were exposed to 10 teratogens during larval development, and subsequently were examined for the pattern of egg-laying and egg quality (hatched larvae and embryo viability) as gravid adults.  After the exposure, adult gravid worms were transferred to untreated plates and the numbers of eggs laid were recorded every 3 hours, and the day following exposure the numbers of hatched larvae were counted. Re sults: While fecundity and fertility were typically impaired by teratogens, unexpectedly, many teratogens initially increased egg-laying at the earliest interval compared to control but not at later intervals. However, egg quality, as assessed by embryo viability, remained the same because many of the eggs (teratogens during early larval development have subtle, long-term effects on egg laying and egg quality. PMID:28163903

  17. Larval food quantity affects development time, survival and adult biological traits that influence the vectorial capacity of Anopheles darlingi under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Araújo Maisa

    2012-08-01

    Full Text Available Abstract Background The incidence of malaria in the Amazon is seasonal and mosquito vectorial capacity parameters, including abundance and longevity, depend on quantitative and qualitative aspects of the larval diet. Anopheles darlingi is a major malaria vector in the Amazon, representing >95% of total Anopheles population present in the Porto Velho region. Despite its importance in the transmission of the Plasmodium parasite, knowledge of the larval biology and ecology is limited. Studies regarding aspects of adult population ecology are more common than studies on larval ecology. However, in order develop effective control strategies and laboratory breeding conditions for this species, more data on the factors affecting vector biology is needed. The aim of the present study is to assess the effects of larval food quantity on the vectorial capacity of An. darling under laboratory conditions. Methods Anopheles darlingi was maintained at 28°C, 80% humidity and exposed to a daily photoperiod of 12 h. Larvae were divided into three experimental groups that were fed either a low, medium, or high food supply (based on the food amounts consumed by other species of culicids. Each experiment was replicated for six times. A cohort of adults were also exposed to each type of diet and assessed for several biological characteristics (e.g. longevity, bite frequency and survivorship, which were used to estimate the vectorial capacity of each experimental group. Results The group supplied with higher food amounts observed a reduction in development time while larval survival increased. In addition to enhanced longevity, increasing larval food quantity was positively correlated with increasing frequency of bites, longer blood meal duration and wing length, resulting in greater vectorial capacity. However, females had greater longevity than males despite having smaller wings. Conclusions Overall, several larval and adult biological traits were significantly

  18. Comparative studies on the larval development of the penaeid shrimps, Penaeus Chinensis, P. merguiensis and P. penicillatus

    Science.gov (United States)

    Liu, Heng; Liu, Rui-Yu

    1994-12-01

    The morphology of larval and 1st postlarval stages of Penaeus penicillatus are described. Results from comparative studies on larval development of P. penicillatus, P. merguiensis and P. chinensis are as follows: These three species could not be identified during their naupliar stages. In the 1st protozoea, the antennule L1/L2 value is 1.7 2.0 in P. merguiensis, but less than 1.7 in P. chinensis and P. penicillatus; in the 2nd protozoea, the supra-orbital spine in P. chinensis is not bifurcated, while those of P. merguiensis and P. penicillatus are bifurcated; in the 3rd protozoea, there is a minute (or no) dorso-median spine on the posterior margin of the 1st and 2nd abdominal somite in P. chinensis, but they are prominent in P. merguiensis and P. penicillatus. In the mysis and 1st postlarval stages, P. chinensis differs from P. merguiensis and P. penicillatus in having 9 (8 in the other 2 species) long setae on the exopod of pereopods 1 3; additionally, one dorsal tooth appears on the rostrum of P. chinensis in the 2nd mysis and that of the other 2 species in the 3rd mysis; P. chinensis has 2 (mostly) or 1 dorsal tooth on the rostrum in the 3rd mysis and 2 3 in the 1st postlarva, while P. penicillatus and P. merguiensis have only 1 in the 3rd mysis and 1st postlarva. Comparative studies on larval development showed P. penicillatus has closer affinity with P. merguiensis than with P. chinensis.

  19. Development of millisecond and internal delayed electric detonators in Hungary

    Energy Technology Data Exchange (ETDEWEB)

    Benedek, D.

    1986-01-01

    The stages of developing millisecond and internal delayed detonators are discussed. The problems of their practical introduction in Hungary as well as the economic background of their production are outlined. The present situation, i.e. production possibilities, application of different detonator types as well as the expected progress in the field of detonator production and use in mines endangered by fire-damp are dealt with.

  20. Desenvolvimento e mortalidade larval de Spodoptera frugiperda em folhas de milho tratadas com extrato aquoso de folhas de Azadirachta indica Larval development and mortality of Spodoptera frugiperda fed on corn leaves treated with aqueous extract from Azadirachta indica leaves

    Directory of Open Access Journals (Sweden)

    Paulo Afonso Viana

    2003-01-01

    Full Text Available Estudou-se o efeito do extrato aquoso de folhas de nim sobre o desenvolvimento e a mortalidade de lagartas recém-eclodidas de Spodoptera frugiperda. Para constatação do efeito de contato e de ingestão, as lagartas foram pulverizadas e as folhas de milho submersas no extrato (10 mg.mL-1 em laboratório e/ou pulverizadas no campo com um pulverizador de CO2. Partes de folhas de milho tratadas foram colocadas em copos plásticos para alimentar as lagartas e trocadas a cada dois dias. Adjuvantes foram adicionados ao extrato visando melhorar sua aderência às superfícies tratadas. Os parâmetros avaliados foram a mortalidade e o desenvolvimento larval. As folhas de milho submergidas e pulverizadas com o extrato causaram elevada mortalidade (100% e prejudicaram o desenvolvimento das lagartas sobreviventes. Na avaliação realizada 10 dias após a aplicação, o espalhante adesivo e o óleo de soja misturados ao extrato melhoraram a eficiência deste. A mortalidade das lagartas ocorreu três dias após a aplicação do extrato e a sua pulverização diretamente sobre o inseto não prejudicou o desenvolvimento larval. O extrato aquoso de nim mostrou-se com potencial para o controle de S. frugiperda.The effect of aqueous extracts from neem leaves and spraying adjuvants were evaluated on development and mortality of neonate S. frugiperda larvae. Corn leaves were dipped in the aqueous extract (10 mg.mL-1 in the laboratory and/or sprayed in the field with a CO2 sprayer and placed in plastic cup for larvae rearing. The treated corn leaves were replaced every other day. Corn leaves submerged and sprayed with the extract caused high larval mortality (100% and showed a negative effect on the larval development. The spreading agent and soybean oil mixed with neem extract improved larval mortality at the end of the 10-day period. The aqueous extract caused lethal effect on S. frugiperda larvae after three days of the application and sprayed directly on the

  1. Survival and larval development of Spodoptera frugiperda (J E Smith) (Lepidoptera: Noctuidae) on alternatives host; Sobrevivencia e desenvolvimento larval de Spodoptera frugiperda (J E Smith) (Lepidoptera: Noctuidae) em hospedeiros alternativos

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Verissimo G.M. de [Universidade Federal de Minas Gerais (UFMG), Montes Claros, MG (Brazil). Dept. de Agronomia; Fonseca, Bernardo V.C. [Universidade FUMEC, Belo Horizonte, MG (Brazil); Boregas, Katia G.B. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Ecologia; Waquil, Jose M. [EMBRAPA Milho e Sorgo, Sete Lagoas, MG (Brazil)]. E-mail: aaquil@cnpms.embrapa.br

    2009-01-15

    Two bioassays were conducted to evaluate the suitability of host plants of fall armyworm (FAW), Spodoptera frugiperda (J E Smith), in the Brazilian agro-ecosystem. Larval development and survival were analyzed by infesting leaves of maize, grain sorghum, Johnson grass, soybean, Brachiaria and tobacco with FAW newly hatched larvae in a no choice test. No significant differences of survival were observed among insects reared on different hosts, except for tobacco, where no survivors were recorded. Larvae fed on soybean and artificial diet grew larger than those fed on the other hosts. The heaviest pupa was observed from larva fed on artificial diet and the lighter from larva fed on Brachiaria grass. No significant differences were reported on larval development time on natural hosts, but it was longer for larvae reared on artificial diet. Three classes of larval development time were observed on maize, four on sorghum, Brachiaria and soybean, and five on artificial diet. Nearly 85% of FAW larvae completed development within 12 d on maize; 77% on grain sorghum, 80% on Johnson grass, 68% on Brachiaria and 83% on soybean within 14 d and 69% on artificial diet within 17 d. The host suitability to FAW decreases from maize to sorghum, soybean and Brachiaria. (author)

  2. Overcrowding-mediated stress alters cell proliferation in key neuroendocrine areas during larval development in Rhinella arenarum.

    Science.gov (United States)

    Distler, Mijal J; Jungblut, Lucas D; Ceballos, Nora R; Paz, Dante A; Pozzi, Andrea G

    2016-02-01

    Exposure to adverse environmental conditions can elicit a stress response, which results in an increase in endogenous corticosterone levels. In early life stages, it has been thoroughly demonstrated that amphibian larval growth and development is altered as a consequence of chronic stress by interfering with the metamorphic process, however, the underlying mechanisms involved have only been partially disentangled. We examined the effect of intraspecific competition on corticosterone levels during larval development of the toad Rhinella arenarum and its ultimate effects on cell proliferation in particular brain areas as well as the pituitary gland. While overcrowding altered the number of proliferating cells in the pituitary gland, hypothalamus, and third ventricle of the brain, no differences were observed in areas which are less associated with neuroendocrine processes, such as the first ventricle of the brain. Apoptosis was increased in hypothalamic regions but not in the pituitary. With regards to pituitary cell populations, thyrotrophs but not somatoatrophs and corticotrophs showed a decrease in the cell number in overcrowded larvae. Our study shows that alterations in growth and development, produced by stress, results from an imbalance in the neuroendocrine systems implicated in orchestrating the timing of metamorphosis.

  3. Stages in the early and larval development of the African catfish Clarias gariepinus (Teleostei, Clariidae).

    Science.gov (United States)

    Olaniyi, Wasiu Adekunle; Omitogun, Ofelia Galman

    2014-08-01

    The African catfish Clarias gariepinus Burchell 1822 is a favourite aquaculture fish in many parts of Africa and Asia because of its hardiness and fast growth rate. In this study, early, post-embryonic and larval developmental stages of C. gariepinus were examined chronologically and described. Photomicrographs of unfertilized matured oocytes from 0 min of fertilization through all cell stages to alevin, to complete yolk absorption, to free swimming larval stages are shown and documented live from lateral and top views, with the aid of a light microscope. Extruded oocytes had a mean diameter of 1 ± 0.1 mm, and possessed a thin perivitelline membrane whose space was filled with a protoplasmic layer. Heartbeat was in the range of 115-160/min prior to hatching. Hatchability rate was 85% and hatching occurred at 17 h at a controlled temperature of 28.5 ± 0.5°C, while ontogeny of the eyes and other organs were discernible. At day 4, larvae mean length was 9.3 ± 0.5 mm, exogenous feeding had commenced fully and melanophores spread cephalocaudally but were concentrated significantly on the head parts. This paper, for the first time, presents the significant chronological developmental stages of C. gariepinus embryology that will have significant implications for genetic manipulation and catfish seed production for aquaculture.

  4. Effects of the dinoflagellate Karenia brevis on larval development in three species of bivalve mollusc from Florida.

    Science.gov (United States)

    Leverone, Jay R; Blake, Norman J; Pierce, Richard H; Shumway, Sandra E

    2006-07-01

    The effects of Karenia brevis (Wilson clone) on larval survival and development of the northern quahog, Mercenaria mercenaria, eastern oyster, Crassostrea virginica and bay scallop, Argopecten irradians, were studied in the laboratory. Larvae were exposed to cultures of whole and lysed cells, with mean total brevetoxin concentrations of 53.8 and 68.9 microgL(-1), respectively. Survival of early (3-day-old) larvae was generally over 85% for all shellfish species at K. brevis densities of 100 cells ml(-1) or less, and not significantly different between whole and lysed culture. At 1000 cells ml(-1), survival was significantly less in lysed culture than whole culture for both M. mercenaria and C. virginica. Survival of late (7-day-old) larvae in all three species was not significantly affected by K. brevis densities of 1000 cells ml(-1) or less. At 5000 cells ml(-1), however, survival was reduced to 37%, 26% and 19% for A. irradians, M. mercenaria and C. virginica, respectively. Development of C. virginica and M. mercenaria larvae was protracted at K. brevis densities of 1000 cells ml(-1). These results suggest that blooms of K. brevis, and particularly their associated brevetoxins, may have detrimental consequences for Florida's shellfisheries by disrupting critical larval processes. Special attention should be paid to blooms of K. brevis where these shellfish occur naturally or where aquaculture and restoration activities are either ongoing or planned.

  5. Influence of the temperature on the early larval development of the Pacific red snapper, Lutjanus peru (Nichols & Murphy, 1922

    Directory of Open Access Journals (Sweden)

    José Antonio Estrada-Godínez

    2015-03-01

    Full Text Available The Pacific red snapper, Lutjanus peru, is a commercially important species throughout its distribution range, making it a good alternative for aquaculture; however, there is few information regarding environmental conditions and their influence on early development of this species. Temperature is one of the main factors affecting embryo and larval development in marine fishes. In this paper, the effects of different temperatures upon hatching rate, growth, consumption of yolk sac and oil droplet and the formation of the digestive system and eye pigmentation were evaluated in larvae of this species under experimental conditions. Eggs incubated between 20 and 32°C showed hatching rates higher than 90%. However, larvae maintained at 26°C showed significantly larger notochord length and were the first to complete the pigmentation of the eyes and the formation of the digestive system when still possessing enough reserves in the yolk sac. Therefore, according to the results obtained, it is recommended that the incubation of eggs and larval rearing in Pacific red snapper takes place between 25 and 26°C.

  6. Developing optimum sample size and multistage sampling plans for Lobesia botrana (Lepidoptera: Tortricidae) larval infestation and injury in northern Greece.

    Science.gov (United States)

    Ifoulis, A A; Savopoulou-Soultani, M

    2006-10-01

    The purpose of this research was to quantify the spatial pattern and develop a sampling program for larvae of Lobesia botrana Denis and Schiffermüller (Lepidoptera: Tortricidae), an important vineyard pest in northern Greece. Taylor's power law and Iwao's patchiness regression were used to model the relationship between the mean and the variance of larval counts. Analysis of covariance was carried out, separately for infestation and injury, with combined second and third generation data, for vine and half-vine sample units. Common regression coefficients were estimated to permit use of the sampling plan over a wide range of conditions. Optimum sample sizes for infestation and injury, at three levels of precision, were developed. An investigation of a multistage sampling plan with a nested analysis of variance showed that if the goal of sampling is focusing on larval infestation, three grape clusters should be sampled in a half-vine; if the goal of sampling is focusing on injury, then two grape clusters per half-vine are recommended.

  7. Silencing of ecdysone receptor, insect intestinal mucin and sericotropin genes by bacterially produced double-stranded RNA affects larval growth and development in Plutella xylostella and Helicoverpa armigera.

    Science.gov (United States)

    Israni, B; Rajam, M V

    2017-04-01

    RNA interference mediated gene silencing, which is triggered by double-stranded RNA (dsRNA), has become a important tool for functional genomics studies in various systems, including insects. Bacterially produced dsRNA employs the use of a bacterial strain lacking in RNaseIII activity and harbouring a vector with dual T7 promoter sites, which allow the production of intact dsRNA molecules. Here, we report an assessment of the functional relevance of the ecdysone receptor, insect intestinal mucin and sericotropin genes through silencing by dsRNA in two lepidopteran insect pests, Helicoverpa armigera and Plutella xylostella, both of which cause serious crop losses. Oral feeding of dsRNA led to significant reduction in transcripts of the target insect genes, which caused significant larval mortality with various moulting anomalies and an overall developmental delay. We also found a significant decrease in reproductive potential in female moths, with a drop in egg laying and compromised egg hatching from treated larvae as compared to controls. dsRNA was stable in the insect gut and was efficiently processed into small interfering RNAs (siRNAs), thus accounting for the phenotypes observed in the present work. The study revealed the importance of these genes in core insect processes, which are essential for insect development and survival. © 2016 The Royal Entomological Society.

  8. Retarded Onchocerca volvulus L1 to L3 larval development in the Simulium damnosum vector after anti-wolbachial treatment of the human host

    Directory of Open Access Journals (Sweden)

    Albers Anna

    2012-01-01

    Full Text Available Abstract Background The human parasite Onchocerca volvulus harbours Wolbachia endosymbionts essential for worm embryogenesis, larval development and adult survival. In this study, the development of Wolbachia-depleted microfilariae (first stage larvae to infective third stage larvae (L3 in the insect vector Simulium damnosum was analysed. Methods Infected volunteers in Cameroon were randomly and blindly allocated into doxycycline (200 mg/day for 6 weeks or placebo treatment groups. After treatment, blackflies were allowed to take a blood meal on the volunteers, captured and dissected for larval counting and DNA extraction for quantitative real-time PCR analysis. Results PCR results showed a clear reduction in Wolbachia DNA after doxycycline treatment in microfilariae from human skin biopsies with > 50% reduction at one month post-treatment, eventually reaching a reduction of > 80%. Larval stages recovered from the insect vector had similar levels of reduction of endosymbiotic bacteria. Larval recoveries were analysed longitudinally after treatment to follow the kinetics of larval development. Beginning at three months post-treatment, significantly fewer L3 were seen in the blackflies that had fed on doxycycline treated volunteers. Concomitant with this, the proportion of second stage larvae (L2 was significantly increased in this group. Conclusions Doxycycline treatment and the resulting decline of Wolbachia endobacteria from the microfilaria resulted in retarded development of larvae in the insect vector. Thus, anti-wolbachial treatment could have an additive effect for interrupting transmission by reducing the number of L3 that can be transmitted by blackflies.

  9. Embryonic, larval, and juvenile development of the sea biscuit Clypeaster subdepressus (Echinodermata: Clypeasteroida.

    Directory of Open Access Journals (Sweden)

    Bruno C Vellutini

    Full Text Available Sea biscuits and sand dollars diverged from other irregular echinoids approximately 55 million years ago and rapidly dispersed to oceans worldwide. A series of morphological changes were associated with the occupation of sand beds such as flattening of the body, shortening of primary spines, multiplication of podia, and retention of the lantern of Aristotle into adulthood. To investigate the developmental basis of such morphological changes we documented the ontogeny of Clypeaster subdepressus. We obtained gametes from adult specimens by KCl injection and raised the embryos at 26 degrees C. Ciliated blastulae hatched 7.5 h after sperm entry. During gastrulation the archenteron elongated continuously while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larvae began to feed in 3 d and were 20 d old at metamorphosis; starved larvae died 17 d after fertilization. Postlarval juveniles had neither mouth nor anus nor plates on the aboral side, except for the remnants of larval spicules, but their bilateral symmetry became evident after the resorption of larval tissues. Ossicles of the lantern were present and organized in 5 groups. Each group had 1 tooth, 2 demipyramids, and 2 epiphyses with a rotula in between. Early appendages consisted of 15 spines, 15 podia (2 types, and 5 sphaeridia. Podial types were distributed in accordance to Lovén's rule and the first podium of each ambulacrum was not encircled by the skeleton. Seven days after metamorphosis juveniles began to feed by rasping sand grains with the lantern. Juveniles survived in laboratory cultures for 9 months and died with wide, a single open sphaeridium per ambulacrum, aboral anus, and no differentiated food grooves or petaloids. Tracking the morphogenesis of early juveniles is a necessary step to elucidate the developmental mechanisms of echinoid growth and important groundwork to clarify homologies between irregular urchins.

  10. Wnt signaling controls the stem cell-like asymmetric division of the epithelial seam cells during C. elegans larval development.

    Science.gov (United States)

    Gleason, Julie E; Eisenmann, David M

    2010-12-01

    Metazoan stem cells repopulate tissues during adult life by dividing asymmetrically to generate another stem cell and a cell that terminally differentiates. Wnt signaling regulates the division pattern of stem cells in flies and vertebrates. While the short-lived nematode C. elegans has no adult somatic stem cells, the lateral epithelial seam cells divide in a stem cell-like manner in each larval stage, usually generating a posterior daughter that retains the seam cell fate and an anterior daughter that terminally differentiates. We show that while wild-type adult animals have 16 seam cells per side, animals with reduced function of the TCF homolog POP-1 have as many as 67 seam cells, and animals with reduced function of the β-catenins SYS-1 and WRM-1 have as few as three. Analysis of seam cell division patterns showed alterations in their stem cell-like divisions in the L2-L4 stages: reduced Wnt signaling caused both daughters to adopt non-seam fates, while activated Wnt signaling caused both daughters to adopt the seam fate. Therefore, our results indicate that Wnt signaling globally regulates the asymmetric, stem cell-like division of most or all somatic seam cells during C. elegans larval development, and that Wnt pathway regulation of stem cell-like behavior is conserved in nematodes. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. A High-Throughput Method for the Analysis of Larval Developmental Phenotypes in Caenorhabditis elegans.

    Science.gov (United States)

    Olmedo, María; Geibel, Mirjam; Artal-Sanz, Marta; Merrow, Martha

    2015-10-01

    Caenorhabditis elegans postembryonic development consists of four discrete larval stages separated by molts. Typically, the speed of progression through these larval stages is investigated by visual inspection of the molting process. Here, we describe an automated method to monitor the timing of these discrete phases of C. elegans maturation, from the first larval stage through adulthood, using bioluminescence. The method was validated with a lin-42 mutant strain that shows delayed development relative to wild-type animals and with a daf-2 mutant that shows an extended second larval stage. This new method is inherently high-throughput and will finally allow dissecting the molecular machinery governing the speed of the developmental clock, which has so far been hampered by the lack of a method suitable for genetic screens.

  12. Incorporation of habitat information in the development of indices of larval bluefin tuna (Thunnus thynnus) in the Western Mediterranean Sea (2001-2005 and 2012-2013)

    Science.gov (United States)

    Ingram, G. Walter; Alvarez-Berastegui, Diego; Reglero, Patricia; Balbín, Rosa; García, Alberto; Alemany, Francisco

    2017-06-01

    Fishery independent indices of bluefin tuna larvae in the Western Mediterranean Sea are presented utilizing ichthyoplankton survey data collected from 2001 through 2005 and 2012 through 2013. Indices were developed using larval catch rates collected using two different types of bongo sampling, by first standardizing catch rates by gear/fishing-style and then employing a delta-lognormal modeling approach. The delta-lognormal models were developed three ways: 1) a basic larval index including the following covariates: time of day, a systematic geographic area variable, month and year; 2) a standard environmental larval index including the following covariates: mean water temperature over the mixed layer depth, mean salinity over the mixed layer depth, geostrophic velocity, time of day, a systematic geographic area variable, month and year; and 3) a habitat-adjusted larval index including the following covariates: a potential habitat variable, time of day, a systematic geographic area variable, month and year. Results indicated that all three model-types had similar precision in index values. However, the habitat-adjusted larval index demonstrated a high correlation with estimates of spawning stock biomass from the previous stock assessment model, and, therefore, is recommended as a tuning index in future stock assessment models.

  13. Larval development of Fasciola hepatica in experimental infections: variations with populations of Lymnaea truncatula.

    Science.gov (United States)

    Vignoles, P; Dreyfuss, G; Rondelaud, D

    2002-06-01

    A retrospective study was undertaken on 70 French populations of Lymnaea truncatula experimentally infected with Fasciola hepatica to determine whether or not susceptibility of snails to infection influenced redial and cercarial production. Results were compared with those obtained from two control populations, known for prevalences higher than 60% when experimentally infected with F. hepatica. In the 70 other populations examined, the prevalences ranged from 2 to 75%. In 55 of these populations, where the prevalence was more than 20%, a high proportion (50.1-56.8%) of snails died after cercarial shedding, whereas in the other groups (non-shedding snails with the most differentiated larvae being free cercariae, rediae containing cercariae, immature rediae, or sporocysts, respectively), snail death was significantly less. In 11 populations, where the prevalence values were 5-19%, only 14% of snails died after cercarial shedding, whereas snails with free cercariae, rediae with cercariae, or immature rediae showed significant increases in snail mortality. In the remaining four snail populations, with prevalences of less than 5%, the most differentiated larval forms were only immature rediae and/or sporocysts. Overall, the number of rediae containing cercariae significantly decreased with decreasing prevalence values. The low prevalence of experimental infection in several populations of snails might be explained by the occurrence of natural infections with miracidia originating from a mammalian host other than cattle, and/or by genetic variability in the susceptibility of snails to infection.

  14. Post-embryonic larval development and metamorphosis of the hydroid Eudendrium racemosum (Cavolini) (Hydrozoa, Cnidaria)

    Science.gov (United States)

    Sommer, C.

    1990-09-01

    The morphology and histology of the planula larva of Eudendrium racemosum (Cavolini) and its metamorphosis into the primary polyp are described from light microscopic observations. The planula hatches as a differentiated gastrula. During the lecithotrophic larval period, large ectodermal mucous cells, embedded between epitheliomuscular cells, secrete a sticky slime. Two granulated cell types occur in the ectoderm that are interpreted as secretory and sensorynervous cells, but might also be representatives of only one cell type with a multiple function. The entoderm consists of yolk-storing gastrodermal cells, digestive gland cells, interstitial cells, cnidoblasts, and premature cnidocytes. The larva starts metamorphosis by affixing its blunt aboral pole to a substratum. While the planula flattens down, the mucous cells penetrate the mesolamella and migrate through the entoderm into the gastral cavity where they are lysed. Subsequently, interstitial cells, cnidoblasts, and premature cnidocytes migrate in the opposite direction, i.e. from entoderm to ectoderm. Then, the polypoid body organization, comprising head (hydranth), stem and foot, all covered by peridermal secretion, becomes recognisable. An oral constriction divides the hypostomal portion of the gastral cavity from the stomachic portion. Within the hypostomal entoderm, cells containing secretory granules differentiate. Following growth and the multiplication of tentacles, the head periderm disappears. A ring of gland cells differentiates at the hydranth's base. The positioning of cnidae in the tentacle ectoderm, penetration of the mouth opening and the multiplication of digestive gland cells enable the polyp to change from lecithotrophic to planktotrophic nutrition.

  15. Looming detection by identified visual interneurons during larval development of the locust Locusta migratoria.

    Science.gov (United States)

    Simmons, Peter J; Sztarker, Julieta; Rind, F Claire

    2013-06-15

    Insect larvae clearly react to visual stimuli, but the ability of any visual neuron in a newly hatched insect to respond selectively to particular stimuli has not been directly tested. We characterised a pair of neurons in locust larvae that have been extensively studied in adults, where they are known to respond selectively to objects approaching on a collision course: the lobula giant motion detector (LGMD) and its postsynaptic partner, the descending contralateral motion detector (DCMD). Our physiological recordings of DCMD axon spikes reveal that at the time of hatching, the neurons already respond selectively to objects approaching the locust and they discriminate between stimulus approach speeds with differences in spike frequency. For a particular approaching stimulus, both the number and peak frequency of spikes increase with instar. In contrast, the number of spikes in responses to receding stimuli decreases with instar, so performance in discriminating approaching from receding stimuli improves as the locust goes through successive moults. In all instars, visual movement over one part of the visual field suppresses a response to movement over another part. Electron microscopy demonstrates that the anatomical substrate for the selective response to approaching stimuli is present in all larval instars: small neuronal processes carrying information from the eye make synapses both onto LGMD dendrites and with each other, providing pathways for lateral inhibition that shape selectivity for approaching objects.

  16. Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic and early larval development

    DEFF Research Database (Denmark)

    Rabatel, Andréane; Febvay, Gérard; Gaget, Karen;

    2013-01-01

    embryonic and the early larval stages of the pea aphid, characterizing, for the first time, the transcriptional profiles in these developmental phases. Our analyses allowed us to identify key genes in the phenylalanine, tyrosine and dopamine pathways and we identified ACYPI004243, one of the four genes...... encoding for the aspartate transaminase (E.C. 2.6.1.1), as specifically regulated during development. Indeed, the tyrosine biosynthetic pathway is crucial for the symbiotic metabolism as it is shared between the two partners, all the precursors being produced by B. aphidicola. Our microarray data...... are supported by HPLC amino acid analyses demonstrating an accumulation of tyrosine at the same developmental stages, with an up-regulation of the tyrosine biosynthetic genes. Tyrosine is also essential for the synthesis of cuticular proteins and it is an important precursor for cuticle maturation: together...

  17. A Dicer-1 gene from white shrimp Litopenaeus vannamei: expression pattern in the processes of immune response and larval development.

    Science.gov (United States)

    Yao, Xuemei; Wang, Lingling; Song, Linsheng; Zhang, Huan; Dong, Chaohua; Zhang, Ying; Qiu, Limei; Shi, Yaohua; Zhao, Jianmin; Bi, Yongkun

    2010-10-01

    Dicer is a member of the RNAase III family which catalyzes the cleavage of double-stranded RNA to small interfering RNAs and micro RNAs, and then directs sequence-specific gene silencing. In this paper, the full-length cDNA of Dicer-1 was cloned from white shrimp Litopenaeus vannamei (designated as LvDcr1). It was of 7636 bp, including a poly A tail, a 5' UTR of 136 bp, a 3' UTR of 78 bp, and an open reading frame (ORF) of 7422 bp encoding a putative protein of 2473 amino acids. The predicted amino acid sequence comprised all recognized functional domains found in other Dicer-1 homologues and showed the highest (97.7%) similarity to the Dicer-1 from tiger shrimp Penaeus mondon. Quantitative real-time PCR was employed to investigate the tissue distribution of LvDcr1 mRNA, and its expression in shrimps under virus challenge and larvae at different developmental stages. The LvDcr1 mRNA could be detected in all examined tissues with the highest expression level in hemocyte, and was up-regulated in hemocytes and gills after virus injection. These results indicated that LvDcr1 was involved in antiviral defense in adult shrimp. During the developmental stages from fertilized egg to postlarva VII, LvDcr1 was constitutively expressed at all examined development stages, but the expression level varied significantly. The highest expression level was observed in fertilized eggs and followed a decrease from fertilized egg to nauplius I stage. Then, the higher levels of expression were detected at nauplius V and postlarva stages. LvDcr1 expression regularly increased at the upper phase of nauplius, zoea and mysis stages than their prophase. The different expression of LvDcr1 in the larval stages could provide clues for understanding the early innate immunity in the process of shrimp larval development.

  18. The larval development of Pinnixa gracilipes Coelho (Decapoda, Pinnotheridae reared in the laboratory O desenvolvimento larval de Pinnixa gracilipes Coelho (Decapoda, Pinnotheridae cultivado em laboratório

    Directory of Open Access Journals (Sweden)

    Jô de F. Lima

    2006-06-01

    Full Text Available Pinnixa gracilipes Coelho, 1997 is a small pinnotherid crab living in association with ghost shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993 in the northeastern region of Pará State, Brazil. Larvae of P. gracilipes were reared in the laboratory from hatching to the megalopa stage. The complete zoeal period averaged 24 days. Mean duration for each larval stage was 5, 4, 4, 5 and 6 days, respectively. In the present study, five zoeal and megalopal stages are described and illustrated in detail. Morphological comparisons with previous reported works on Pinnotheridae larvae are briefly discussed.Pinnixa gracilipes Coelho, 1997 é um pequeno caranguejo pinoterídeo que vive em associação com Lepidophthalmus siriboia Felder & Rodrigues, 1993 no nordeste do Estado do Pará, Brasil. Larvas de P. gracilipes foram cultivadas em laboratório desde o nascimento ao estágio megalopa. O desenvolvimento completo durou cerca de 24 dias. O per��odo médio de cada estágio foi 5, 4, 4, 5 e 6 dias, respectivamente. No presente trabalho, os cinco estágios zoeae e megalopa são descritos e ilustrados em detalhes. Comparações morfológicas com estudos anteriores sobre larvas da família Pinnotheridae são brevemente discutidas.

  19. She’s a femme fatale: low-density larval development produces good disease vectors

    Directory of Open Access Journals (Sweden)

    Steven A Juliano

    2014-12-01

    Full Text Available Two hypotheses for how conditions for larval mosquitoes affect vectorial capacity make opposite predictions about the relationship of adult size and frequency of infection with vector-borne pathogens. Competition among larvae produces small adult females. The competition-susceptibility hypothesis postulates that small females are more susceptible to infection and predicts frequency of infection should decrease with size. The competition-longevity hypothesis postulates that small females have lower longevity and lower probability of becoming competent to transmit the pathogen and thus predicts frequency of infection should increase with size. We tested these hypotheses for Aedes aegypti in Rio de Janeiro, Brazil, during a dengue outbreak. In the laboratory, longevity increases with size, then decreases at the largest sizes. For field-collected females, generalised linear mixed model comparisons showed that a model with a linear increase of frequency of dengue with size produced the best Akaike’s information criterion with a correction for small sample sizes (AICc. Consensus prediction of three competing models indicated that frequency of infection increases monotonically with female size, consistent with the competition-longevity hypothesis. Site frequency of infection was not significantly related to site mean size of females. Thus, our data indicate that uncrowded, low competition conditions for larvae produce the females that are most likely to be important vectors of dengue. More generally, ecological conditions, particularly crowding and intraspecific competition among larvae, are likely to affect vector-borne pathogen transmission in nature, in this case via effects on longevity of resulting adults. Heterogeneity among individual vectors in likelihood of infection is a generally important outcome of ecological conditions impacting vectors as larvae.

  20. Interactive effect of elevated pCO2 and temperature on the larval development of an inter-tidal organism, Balanus amphitrite Darwin (Cirripedia: Thoracica)

    Digital Repository Service at National Institute of Oceanography (India)

    Baragi, L.V.; Anil, A.C.

    inter-tidal organism, to investigate the effect of these variables on its larval development and metamorphosis. Four alternate combinations of temperature and pCO2: (1) control (~30 °C and ~400 μatm); (2) elevated pCO2 (~30 °C...

  1. GROWTH AND VARIATIONS IN LIPID CLASS AND FATTY ACID COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986.

    Science.gov (United States)

    Larval development in decapod crustaceans is marked by variable growth patterns and changes in weight and biochemical composition. Larvae of the stone crab, Menippe adina, were mass-reared under laboratory conditions (28?C; 20o/ooS) from hatching to the megalopa stage. Growth in...

  2. Reproduction and larval development in three scalpellid barnacles, Scalpellum scalpellum (Linnaeus 1767), Ornatoscalpellum stroemii (M. Sars 1859) and Arcoscalpellum michelottianum (Seguenza 1876), Crustacea: Cirripedia: Thoracica): implications for reproduction

    DEFF Research Database (Denmark)

    Buhl-Mortensen, Lene; Høeg, Jens Thorvald

    2006-01-01

    We studied reproduction and larval development in three species of pedunculated barnacles with different depth distribution, that is, Scalpellum scalpellum (30-200 m), Ornatoscalpellum stroemii (100-1,600 m) and Arcoscalpellum michelottianum (64-5,190 m). Morphology, position and number of males ...

  3. Abbreviation of larval development and extension of brood care as key features of the evolution of freshwater Decapoda.

    Science.gov (United States)

    Vogt, Günter

    2013-02-01

    The transition from marine to freshwater habitats is one of the major steps in the evolution of life. In the decapod crustaceans, four groups have colonized fresh water at different geological times since the Triassic, the freshwater shrimps, freshwater crayfish, freshwater crabs and freshwater anomurans. Some families have even colonized terrestrial habitats via the freshwater route or directly via the sea shore. Since none of these taxa has ever reinvaded its environment of origin the Decapoda appear particularly suitable to investigate life-history adaptations to fresh water. Evolutionary comparison of marine, freshwater and terrestrial decapods suggests that the reduction of egg number, abbreviation of larval development, extension of brood care and lecithotrophy of the first posthatching life stages are key adaptations to fresh water. Marine decapods usually have high numbers of small eggs and develop through a prolonged planktonic larval cycle, whereas the production of small numbers of large eggs, direct development and extended brood care until the juvenile stage is the rule in freshwater crayfish, primary freshwater crabs and aeglid anomurans. The amphidromous freshwater shrimp and freshwater crab species and all terrestrial decapods that invaded land via the sea shore have retained ocean-type planktonic development. Abbreviation of larval development and extension of brood care are interpreted as adaptations to the particularly strong variations of hydrodynamic parameters, physico-chemical factors and phytoplankton availability in freshwater habitats. These life-history changes increase fitness of the offspring and are obviously favoured by natural selection, explaining their multiple origins in fresh water. There is no evidence for their early evolution in the marine ancestors of the extant freshwater groups and a preadaptive role for the conquest of fresh water. The costs of the shift from relative r- to K-strategy in freshwater decapods are traded

  4. Transcriptomic Analysis of Differentially Expressed Genes During Larval Development of Rapana venosa by Digital Gene Expression Profiling

    Directory of Open Access Journals (Sweden)

    Hao Song

    2016-07-01

    Full Text Available During the life cycle of shellfish, larval development, especially metamorphosis, has a vital influence on the dynamics, distribution, and recruitment of natural populations, as well as seed breeding. Rapana venosa, a carnivorous gastropod, is an important commercial shellfish in China, and is an ecological invader in the United States, Argentina, and France. However, information about the mechanism of its early development is still limited, because research in this area has long suffered from a lack of genomic resources. In this study, 15 digital gene expression (DGE libraries from five developmental stages of R. venosa were constructed and sequenced on the IIIumina Hi-Sequation 2500 platform. Bioinformaticsanalysis identified numerous differentially and specifically expressed genes, which revealed that genes associated with growth, nervous system, digestive system, immune system, and apoptosis participate in important developmental processes. The functional analysis of differentially expressed genes was further implemented by gene ontology, and Kyoto encyclopedia of genes and genomes enrichment. DGE profiling provided a general picture of the transcriptomic activities during the early development of R. venosa, which may provide interesting hints for further study. Our data represent the first comparative transcriptomic information available for the early development of R. venosa, which is a prerequisite for a better understanding of the physiological traits controlling development.

  5. Transcriptomic Analysis of Differentially Expressed Genes During Larval Development of Rapana venosa by Digital Gene Expression Profiling.

    Science.gov (United States)

    Song, Hao; Yu, Zheng-Lin; Sun, Li-Na; Xue, Dong-Xiu; Zhang, Tao; Wang, Hai-Yan

    2016-07-07

    During the life cycle of shellfish, larval development, especially metamorphosis, has a vital influence on the dynamics, distribution, and recruitment of natural populations, as well as seed breeding. Rapana venosa, a carnivorous gastropod, is an important commercial shellfish in China, and is an ecological invader in the United States, Argentina, and France. However, information about the mechanism of its early development is still limited, because research in this area has long suffered from a lack of genomic resources. In this study, 15 digital gene expression (DGE) libraries from five developmental stages of R. venosa were constructed and sequenced on the IIIumina Hi-Sequation 2500 platform. Bioinformaticsanalysis identified numerous differentially and specifically expressed genes, which revealed that genes associated with growth, nervous system, digestive system, immune system, and apoptosis participate in important developmental processes. The functional analysis of differentially expressed genes was further implemented by gene ontology, and Kyoto encyclopedia of genes and genomes enrichment. DGE profiling provided a general picture of the transcriptomic activities during the early development of R. venosa, which may provide interesting hints for further study. Our data represent the first comparative transcriptomic information available for the early development of R. venosa, which is a prerequisite for a better understanding of the physiological traits controlling development.

  6. Perinatal asphyxia: CNS development and deficits with delayed onset

    Directory of Open Access Journals (Sweden)

    Mario eHerrera-Marschitz

    2014-03-01

    Full Text Available Perinatal asphyxia constitutes a prototype of obstetric complications occurring when pulmonary oxygenation is delayed or interrupted. The primary insult relates to the duration of the period lacking oxygenation, leading to death if not re-established. Re-oxygenation leads to a secondary insult, related to a cascade of biochemical events required for restoring proper function. Perinatal asphyxia interferes with neonatal development, resulting in long-term deficits associated to mental and neurological diseases with delayed clinical onset, by mechanisms not yet clarified.In the experimental scenario, the effects observed long after perinatal asphyxia have been explained by over expression of sentinel proteins, such as poly(ADP-ribose polymerase-1 (PARP-1, competing for NAD+ during re-oxygenation, leading to the idea that sentinel protein inhibition constitutes a suitable therapeutic strategy. Asphyxia induces transcriptional activation of pro-inflammatory factors, in tandem with PARP-1 overactivation, and pharmacologically induced PARP-1 inhibition also down-regulates the expression of proinflammatory cytokines. Nicotinamide has been proposed as a suitable PARP-1 inhibitor. Its effect has been studied in an experimental model of global hypoxia in rats. In that model, the insult is induced by immersing rat foetuses into a water bath for various periods of time. Following asphyxia, the pups are delivered, treated, and nursed by surrogate dams, pending further experiments. Nicotinamide rapidly distributes into the brain following systemic administration, reaching steady state concentrations sufficient to inhibit PARP-1 activity for several hours, preventing several of the long-term consequences of perinatal asphyxia, supporting the idea that it constitutes a lead for exploring compounds with similar or better pharmacological profiles.

  7. The development of a cryogenic optical delay line for DARWIN

    NARCIS (Netherlands)

    Dool, T.C. van den; Kamphues, F.G.

    2005-01-01

    TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard (BB) delay line is

  8. Do long delay conditioned stimuli develop inhibitory properties?

    Directory of Open Access Journals (Sweden)

    Martha eEscobar

    2015-10-01

    Full Text Available In long-delay conditioning, a long conditioned stimulus (CS is paired in its final segments with an unconditioned stimulus. With sufficient training, this procedure usually results in conditioned responding being delayed until the final segment of the CS, a pattern of responding known as inhibition of delay. However, there have been no systematic investigations of the associative structure of long delay conditioning, and whether the initial segment of a long delay CS actually becomes inhibitory is debatable. In an appetitive preparation with rat subjects, the initial segment of long delay CS A passed a retardation (Experiment 1a but not a summation (Experiment 1b test for conditioned inhibition. Furthermore, retardation was observed only if long delay conditioning and retardation training occurred in the same context (Experiment 2. Thus, the initial segment of a long delay CS appears to share more characteristics with a latent inhibitor than a conditioned inhibitor. Componential theories of conditioning appear best suited to account for these results.

  9. Patterning the dorsal longitudinal flight muscles (DLM) of Drosophila: insights from the ablation of larval scaffolds

    Science.gov (United States)

    Fernandes, J. J.; Keshishian, H.

    1996-01-01

    The six Dorsal Longitudinal flight Muscles (DLMs) of Drosophila develop from three larval muscles that persist into metamorphosis and serve as scaffolds for the formation of the adult fibers. We have examined the effect of muscle scaffold ablation on the development of DLMs during metamorphosis. Using markers that are specific to muscle and myoblasts we show that in response to the ablation, myoblasts which would normally fuse with the larval muscle, fuse with each other instead, to generate the adult fibers in the appropriate regions of the thorax. The development of these de novo DLMs is delayed and is reflected in the delayed expression of erect wing, a transcription factor thought to control differentiation events associated with myoblast fusion. The newly arising muscles express the appropriate adult-specific Actin isoform (88F), indicating that they have the correct muscle identity. However, there are frequent errors in the number of muscle fibers generated. Ablation of the larval scaffolds for the DLMs has revealed an underlying potential of the DLM myoblasts to initiate de novo myogenesis in a manner that resembles the mode of formation of the Dorso-Ventral Muscles, DVMs, which are the other group of indirect flight muscles. Therefore, it appears that the use of larval scaffolds is a superimposition on a commonly used mechanism of myogenesis in Drosophila. Our results show that the role of the persistent larval muscles in muscle patterning involves the partitioning of DLM myoblasts, and in doing so, they regulate formation of the correct number of DLM fibers.

  10. Crustacean biodiversity as an important factor for mosquito larval control.

    Science.gov (United States)

    Kroeger, Iris; Duquesne, Sabine; Liess, Matthias

    2013-12-01

    Newly established ponds, which are highly dynamic systems with changing levels of biological interactions among species, are common larval mosquito habitats. We investigated the impact of crustacean abundance and taxa diversity on mosquito oviposition and larval development. The effects of the biological larvicide Bacillus thuringiensis israelensis (Bti) on mosquito larvae were monitored according to fluctuations in crustacean communities. Populations of the mosquito Culex pipiens colonized artificial ponds that contained crustacean communities at different time points of colonization by crustaceans: 1) 'no colonization' (no crustaceans), 2) 'simultaneous colonization' by crustaceans and mosquitoes, and 3) 'head-start colonization' by crustaceans (preceding colonization by mosquitoes). All types of ponds were treated with three concentrations of Bti (10, 100, or 1,000 µg/liter). Colonization of all ponds by Cx. pipiens (in terms of oviposition, larval abundance, and larval development) decreased significantly with increasing diversity of crustacean taxa. The total abundance of crustaceans had a minor effect on colonization by Cx. pipiens. The presence of crustaceans increased the sensitivity of Cx. pipiens larvae to Bti treatment by a factor of 10 and delayed the time of recolonization. This effect of Bti was relevant in the short term. In the long term, the presence of Cx. pipiens was determined by crustacean biodiversity. © 2013 The Society for Vector Ecology.

  11. Effects of larval crowding on development time, survival and weight at metamorphosis in Aedes aegypti (Diptera: Culicidae Efectos del hacinamiento larval en el tiempo de desarrollo, la supervivencia y el peso en la metamorfosis de Aedes aegypti (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Arnaldo Maciá

    2009-06-01

    Full Text Available The effects of larval crowding on survival, weight at metamorphosis and development time were assessed in the dengue mosquito, Aedes aegypti L., under a controlled environment. Larval cohorts were bred at 7 different densities (4, 8, 16, 32, 64, 128 and 256 larvae / 175 ml pot, while keeping constant water volume and food amount and quality, under controlled temperature and photoperiod. Natural detritus, mainly leaves, obtained from containers naturally colonized by A. aegypti, were used as a source of nutrients for larvae. Development time, mortality, mass at metamorphosis, and total biomass were recorded for each density. Development time ranged from 4 to 23 days in males, and from 5 to 24 in females, whereby larvae took longer to develop at 64 (females and 128 (males larvae per recipient. At high densities there was a male-biased sex proportion. At densities equal to or higher than 0.4 larvae/ml (0.32 larvae/cm² there was an increase of mortality. An inverse relationship between larval density and pupal weight was detected. Biomass per individual reached asymptotic values of about 1 mg/individual at a density of 128 individuals/pot (0.64 larvae/cm². This experiment shows that this southern strain of A. aegypti is sensitive to crowding in small containers.Los efectos del hacinamiento larval sobre el tiempo de desarrollo, la supervivencia y el peso en la metamorfosis fueron estudiados en el mosquito del dengue, Aedes aegypti L., en el laboratorio. Se criaron cohortes de larvas en 7 densidades (4, 8, 16, 32, 64, 128 y 256 larvas/ recipiente de 175 ml mientras se mantuvo constante el volumen de agua y la calidad y cantidad de alimento, bajo fotoperíodo y temperatura controlados. Se usaron detritos naturales, principalmente hojas, obtenidos de contenedores colonizados naturalmente por A. aegypti como fuente de nutrientes para las larvas. En cada densidad se registraron el tiempo de desarrollo, la mortalidad, el peso en la metamorfosis y la

  12. EFFECTS OF TEMPERATURE AND Ca2+ ON THE LARVAL DEVELOPMENT OF THE DECAPODA CRUSTACEAN : ERIOCHEIR SINENSIS

    Institute of Scientific and Technical Information of China (English)

    黄勃; 堵南山; 赖伟

    2001-01-01

    With increasing demand in China for the mitten crab larvae, understanding its survival mechanism gets more important. This research focused on the effects of temperature and Ca2+ on the larval growth and development. Eriocheir sinensis larvae were reared in laboratory under 21 different combinations of temperature (15, 20, 25℃) and Ca2+ content (120, 130, 140, 150, 160, 170, 180mg/l) and constant salinity (20) and pH (8), The results suggested that the survival rate increases with temperature and Ca2+ content. These combinations of temperature and Ca2+ content maximized survival rate inour study and it may be the optimum water environmental conditions for culturing the larvae. To predict surviving larvae number under different water environmental conditions, 21 dynamic mathematical models were developed. This for the first time observation of the zoeal Ⅵ larvae of the Changjiang River E.sinensis population showed that they occurred under stressed water environmental conditions: temperature of 15℃ and Ca2+ content of 120,130mg/l.

  13. Starvation stress during larval development facilitates an adaptive response in adult worker honey bees (Apis mellifera L.).

    Science.gov (United States)

    Wang, Ying; Kaftanoglu, Osman; Brent, Colin S; Page, Robert E; Amdam, Gro V

    2016-04-01

    Most organisms are constantly faced with environmental changes and stressors. In diverse organisms, there is an anticipatory mechanism during development that can program adult phenotypes. The adult phenotype would be adapted to the predicted environment that occurred during organism maturation. However, whether this anticipatory mechanism is present in eusocial species is questionable because eusocial organisms are largely shielded from exogenous conditions by their stable nest environment. In this study, we tested whether food deprivation during development of the honey bee (Apis mellifera), a eusocial insect model, can shift adult phenotypes to better cope with nutritional stress. After subjecting fifth instar worker larvae to short-term starvation, we measured nutrition-related morphology, starvation resistance, physiology, endocrinology and behavior in the adults. We found that the larval starvation caused adult honey bees to become more resilient toward starvation. Moreover, the adult bees were characterized by reduced ovary size, elevated glycogen stores and juvenile hormone (JH) titers, and decreased sugar sensitivity. These changes, in general, can help adult insects survive and reproduce in food-poor environments. Overall, we found for the first time support for an anticipatory mechanism in a eusocial species, the honey bee. Our results suggest that this mechanism may play a role in honey bee queen-worker differentiation and worker division of labor, both of which are related to the responses to nutritional stress.

  14. A case of acutely developed delayed radiation myelopathy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Shintaro; Amari, Masakuni [Geriatrics Research Inst., Maebashi (Japan). Hospital; Fukuda, Toshio; Okamoto, Koichi [Gunma Univ., Maebashi (Japan). School of Medicine

    2002-08-01

    A 66-year-old man with a history of hypertension received radiation therapy on his neck at age 61 because of laryngeal cancer (T1bN0M0). Five years after the radiation, he acutely developed dysuria, tetraparesis and dissociated sensory disturbances below bilateral Th4 level. T2 weighted MRI showed a high signal lesion affecting the central area of the spinal cord extending from C1 to C7. On the second clinical day, he developed respiratory arrest and was ventilated. The cerebrospinal fluid contained 20/mm{sup 3} (monocyte 15, neutorophil 5) white cells; protein was 52.5 mg/dl; IgG index 0.54; Q albumin was 9.6; tests for oligoclonal band and myelin basic protein were negative; a culture yielded no microorganism. He was treated with steroids and supportive measures without improvement, and died of a sudden cardiac arrest on the 8th clinical day. postmortem examination confirmed conspicuous focal spongy changes with many axonal swellings, especially in the posterior and lateral columns at cervical and Th1 levels. The pathological findings were considered to be compatible with those of delayed radiation myelopathy (DRM). In the anterior horn of the cervical cord there were lesions of diffuse racification and the proliferation of small vessels. There were no findings of hyaline vascular changes, infarction or metastasis of laryngeal cancer at the spinal cord. It is considered that hyperintensity of signals on T2-weighted may originate from racification and proliferation of small vessels in the gray matter, and these pathological changes would be intimately associated with the severe neurologic morbidity of this patient. Acute development of neurological findings and the pathological changes in the gray matter of the spinal cord are rare manifestations of DRM. (author)

  15. Delays in GABAergic interneuron development and behavioral inhibition after prenatal stress

    National Research Council Canada - National Science Library

    Lussier, Stephanie J; Stevens, Hanna E

    2016-01-01

    .... Prenatal stress delays GABAergic progenitor migration, but the significance of these early developmental disruptions for the continued development of GABAergic cells in the juvenile brain is unclear...

  16. Development of Trichosomoides nasalis (Nematoda: Trichinelloidea in the murid host: evidence for larval growth in striated muscle fibres

    Directory of Open Access Journals (Sweden)

    Fall E.H.

    2012-02-01

    Full Text Available Trichosomoides nasalis (Trichinelloidea is a parasite of Arvicanthis niloticus (Muridae in Senegal. Female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. Young laboratory-bred A. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. Both resulted in successful infection. Organs examined during rodent necropsy were blood and lymphatic circulatory systems (heart, large vessels, lymphnodes, lungs, liver, kidneys, thoracic and abdominal cavities, thoracic and abdominal muscular walls, diaphragm, tongue, and nasal mucosa. Development to adult nasal stages took three weeks. Recovery of newly hatched larvae from the peritoneal fluid at four-eight hours after oral infection suggests a direct passage from the stomach or intestinal wall to the musculature. However, dissemination through the blood, as observed with Trichinella spiralis, cannot be excluded even though newly hatched larvae of T. nasalis are twice as thick (15 μm. Developing larvae were found in histological sections of the striated muscle of the abdominal and thoracic walls, and larvae in fourth moult were dissected from these sites. Adult females were found in the deep nasal mucosa where mating occurred prior to worms settling in the nasal epithelium. The present study shows a remarkable similarity between T. nasalis and Trichinella species regarding muscle tropism, but the development of T. nasalis is not arrested at the late first-larval stage and does not induce transformation of infected fibres into nurse cells. T. nasalis seems a potential model to study molecular relations between trichinelloid larvae and infected muscle fibres.

  17. Development of Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host: evidence for larval growth in striated muscle fibres.

    Science.gov (United States)

    Fall, E H; Diagne, M; Junker, K; Duplantier, J M; Ba, K; Vallée, I; Bain, O

    2012-02-01

    Trichosomoides nasalis (Trichinelloidea) is a parasite of Arvicanthis niloticus (Muridae) in Senegal. Female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. Young laboratory-bred A. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. Both resulted in successful infection. Organs examined during rodent necropsy were blood and lymphatic circulatory systems (heart, large vessels, lymphnodes), lungs, liver, kidneys, thoracic and abdominal cavities, thoracic and abdominal muscular walls, diaphragm, tongue, and nasal mucosa. Development to adult nasal stages took three weeks. Recovery of newly hatched larvae from the peritoneal fluid at four-eight hours after oral infection suggests a direct passage from the stomach or intestinal wall to the musculature. However, dissemination through the blood, as observed with Trichinella spiralis, cannot be excluded even though newly hatched larvae of T. nasalis are twice as thick (15 μm). Developing larvae were found in histological sections of the striated muscle of the abdominal and thoracic walls, and larvae in fourth moult were dissected from these sites. Adult females were found in the deep nasal mucosa where mating occurred prior to worms settling in the nasal epithelium. The present study shows a remarkable similarity between T. nasalis and Trichinella species regarding muscle tropism, but the development of T. nasalis is not arrested at the late first-larval stage and does not induce transformation of infected fibres into nurse cells. T. nasalis seems a potential model to study molecular relations between trichinelloid larvae and infected muscle fibres.

  18. Development of an automated imaging pipeline for the analysis of the zebrafish larval kidney.

    Directory of Open Access Journals (Sweden)

    Jens H Westhoff

    Full Text Available The analysis of kidney malformation caused by environmental influences during nephrogenesis or by hereditary nephropathies requires animal models allowing the in vivo observation of developmental processes. The zebrafish has emerged as a useful model system for the analysis of vertebrate organ development and function, and it is suitable for the identification of organotoxic or disease-modulating compounds on a larger scale. However, to fully exploit its potential in high content screening applications, dedicated protocols are required allowing the consistent visualization of inner organs such as the embryonic kidney. To this end, we developed a high content screening compatible pipeline for the automated imaging of standardized views of the developing pronephros in zebrafish larvae. Using a custom designed tool, cavities were generated in agarose coated microtiter plates allowing for accurate positioning and orientation of zebrafish larvae. This enabled the subsequent automated acquisition of stable and consistent dorsal views of pronephric kidneys. The established pipeline was applied in a pilot screen for the analysis of the impact of potentially nephrotoxic drugs on zebrafish pronephros development in the Tg(wt1b:EGFP transgenic line in which the developing pronephros is highlighted by GFP expression. The consistent image data that was acquired allowed for quantification of gross morphological pronephric phenotypes, revealing concentration dependent effects of several compounds on nephrogenesis. In addition, applicability of the imaging pipeline was further confirmed in a morpholino based model for cilia-associated human genetic disorders associated with different intraflagellar transport genes. The developed tools and pipeline can be used to study various aspects in zebrafish kidney research, and can be readily adapted for the analysis of other organ systems.

  19. Analysis of Delays in Hard Rock Mine Lateral Development: A Case Study

    Directory of Open Access Journals (Sweden)

    P.A. Eshun

    2011-11-01

    Full Text Available The aim of this study is to identify and isolate the major causes of delays in underground lateral development at AngloGold Ashanti (AGA, Obuasi Mine, Ghana. It uses fishbone analysis to identify and present 20 possible causes of delays in lateral development at the mine. By employing Pareto analysis, 7 major causes of delays have been isolated. They are: scoop problems, low compressed air, labour shortages, bad ground, flood, power outages and waste pass getting full. The study concludes that, should management concentrate in minimising the 7 major causes of delays, it will be solving about 80% of the problems associated with delays in underground lateral development at AGA, Obuasi mine. The study further gives specific recommendations to reduce delays in lateral development at the mine.

  20. EGF-mediated EGFR/ERK signaling pathway promotes germinative cell proliferation in Echinococcus multilocularis that contributes to larval growth and development.

    Science.gov (United States)

    Cheng, Zhe; Liu, Fan; Li, Xiu; Dai, Mengya; Wu, Jianjian; Guo, Xinrui; Tian, Huimin; Heng, Zhijie; Lu, Ying; Chai, Xiaoli; Wang, Yanhai

    2017-02-01

    Larvae of the tapeworm E. multilocularis cause alveolar echinococcosis (AE), one of the most lethal helminthic infections in humans. A population of stem cell-like cells, the germinative cells, is considered to drive the larval growth and development within the host. The molecular mechanisms controlling the behavior of germinative cells are largely unknown. Using in vitro cultivation systems we show here that the EGFR/ERK signaling in the parasite can promote germinative cell proliferation in response to addition of human EGF, resulting in stimulated growth and development of the metacestode larvae. Inhibition of the signaling by either the EGFR inhibitors CI-1033 and BIBW2992 or the MEK/ERK inhibitor U0126 impairs germinative cell proliferation and larval growth. These data demonstrate the contribution of EGF-mediated EGFR/ERK signaling to the regulation of germinative cells in E. multilocularis, and suggest the EGFR/ERK signaling as a potential therapeutic target for AE and perhaps other human cestodiasis.

  1. Larval development and metamorphosis of Balanus albicostatus (Cirripedia: Thoracica); implications of temperature, food concentration and energetics

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.; Khandeparker, L.; Shirayama, Y.

    The influence of food concentrations (0.5, 1 and 2 x 105 cells ml sup(-1)) and temperatures (20 and 30 degrees C) on the survival, development, organic carbon and nitrogen content of Balanus albicostatus larvae was evaluated The effect of food...

  2. Analysis of Delays in Hard Rock Mine Lateral Development: A Case Study

    OpenAIRE

    P.A. Eshun; V.A. Temeng

    2011-01-01

    The aim of this study is to identify and isolate the major causes of delays in underground lateral development at AngloGold Ashanti (AGA), Obuasi Mine, Ghana. It uses fishbone analysis to identify and present 20 possible causes of delays in lateral development at the mine. By employing Pareto analysis, 7 major causes of delays have been isolated. They are: scoop problems, low compressed air, labour shortages, bad ground, flood, power outages and waste pass getting full. The study concludes th...

  3. First feeding of larval herring

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Munk, Peter; Støttrup, Josianne

    1985-01-01

    The transition period from endogenous to exogenous feeding by larval herring was investigated in the laboratory for four herring stocks in order to evaluate the chances of survival at the time of fiest feeding. Observations on larval activity, feeding and growth were related to amount of yolk......, visual experience with potential prey organisms prior to first feeding and prey density. Herring larvae did not initiate exogenous feeding until around the time of yolk resorption. The timing of first feeding was not influenced by prior exposure to potential prey organisms during the yolk sac stage....... In the light of these observations, the ecological significance of the yolk sac stage is discussed. Initiation of exogenous feeding was delayed by 1-4 days at a low (7.5 nauplii .cntdot. l-1) compared to a high (120 nauplii .cntdot. l-1) prey density, but even at prey densities corresponding to the lower end...

  4. Regional expression of Pax7 in the brain of Xenopus laevis during embryonic and larval development

    Directory of Open Access Journals (Sweden)

    Sandra eBandín

    2013-12-01

    Full Text Available Pax7 is a member of the highly conserved Pax gene family that is expressed in restricted zones of the central nervous system during development, being involved in early brain regionalization and the maintenance of the regional identity. Using sensitive immunohistochemical techniques we have analyzed the spatiotemporal pattern of Pax7 expression in the brain of the anuran amphibian Xenopus laevis, during development. Pax7 expression was first detected in early embryos in the basal plate of prosomere 3, roof and alar plates of prosomere 1 and mesencephalon, and the alar plate of rhombomere 1. As development proceeded, Pax7 cells were observed in the hypothalamus close to the catecholaminergic population of the mammillary region. In the diencephalon, Pax7 was intensely expressed in a portion of the basal plate of prosomere 3, in the roof plate and in scattered cells of the thalamus in prosomere 2, throughout the roof of prosomere 1, and in the commissural and juxtacommissural domains of the pretectum. In the mesencephalon, Pax7 cells were localized in the optic tectum and, to a lesser extent, in the torus semicircularis. The rostral portion of the alar part of rhombomere 1, including the ventricular layer of the cerebellum, expressed Pax7 and, gradually, some of these dorsal cells were observed to populate ventrally the interpeduncular nucleus and the isthmus (rhombomere 0. Additionally, Pax7 positive cells were found in the ventricular zone of the ventral part of the alar plate along the rhombencephalon and the spinal cord. The findings show that the strongly conserved features of Pax7 expression through development shared by amniote vertebrates are also present in the anamniote amphibians as a common characteristic of the brain organization of tetrapods.

  5. Anatomy and development of the larval nervous system in Echinococcus multilocularis

    OpenAIRE

    Brehm, Klaus; Koziol, Uriel; Krohne, Georg

    2013-01-01

    Background The metacestode larva of Echinococcus multilocularis (Cestoda: Taeniidae) develops in the liver of intermediate hosts (typically rodents, or accidentally in humans) as a labyrinth of interconnected cysts that infiltrate the host tissue, causing the disease alveolar echinococcosis. Within the cysts, protoscoleces (the infective stage for the definitive canid host) arise by asexual multiplication. These consist of a scolex similar to that of the adult, invaginated within a small ...

  6. Otolith development in larval and juvenile Schizothorax davidi: ontogeny and growth increment characteristics

    Science.gov (United States)

    Yan, Taiming; Hu, Jiaxiang; Cai, Yueping; Xiong, Sen; Yang, Shiyong; Wang, Xiongyan; He, Zhi

    2016-09-01

    Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David's schizothoracin otoliths. Otolith development was observed and their formation period was verified by monitoring larvae and juveniles of known age. The results revealed that lapilli and sagittae developed before hatching, and the first otolith increment was identified at 2 days post hatching in both. The shape of lapilli was relatively stable during development compared with that of sagittae; however, growth of four sagittae and lapilli areas was consistent, but the posterior area grew faster than the anterior area and the ventral surface grew faster than the dorsal surface. Similarly, the sum length of the radius of the anterior and posterior areas on sagittae and lapilli were linearly and binomially related to total fish length, respectively. Moreover, daily deposition rates were validated by monitoring known-age larvae and juveniles. The increase in lapilli width was 1.88±0.080 0 μm at the ninth increment, which reached a maximum and the decreased gradually toward the otolith edge, whereas that of sagittae increased more slowly. These results illustrate the developmental biology of S. davidi, which will aid in population conservation and fish stock management.

  7. Observations on the morphology of embryonic and larval development in Styela canopus Savigny

    Institute of Scientific and Technical Information of China (English)

    Huang Ying; Ke Caihuan; Feng Danqing; Zhou Shiqiang; Li Fuxue

    2003-01-01

    The morphological characters on different developmental phases of embryo and larva and the schedule of the whole early developmental process in Styela canopus were observed and described.The types of reproduction and early development as well as the morphology of egg and larva in different ascidian species were compared. Styela canopus is oviparous. Its egg, 230.4~336.0 μm in diameter, is equipped with extraembryonic cell layers measured 43.2~ 63.0 μm thick. The early development of Styela canopus is typical urodele development, including fertilization, cleavage, gastrulation, tadpole in membrane, tadpole, initiating metamorphosis and juvenile. The tadpole of Styela canopus, with a length of 0.6~0.9 mm, consists of trunk and tail. There are obvious notochord, ocellus and adhesive papillae in the tadpole. Under the water temperature of (25 ± 0.5)℃ and the salinity of 27.0, the larva was hatched after 9.5~ 11.0 h since the fertilization.

  8. Suitability of monotypic and mixed diets for Anopheles hermsi larval development.

    Science.gov (United States)

    Beasley, Donald A; Walton, William E

    2016-06-01

    The developmental time and survival to eclosion of Anopheles hermsi Barr & Guptavanij fed monotypic and mixed diets of ten food types were examined in laboratory studies. Larvae fed monotypic diets containing animal detritus (freeze-dried rotifers, freeze-dried Daphnia pulicaria, and TetraMin® fish food flakes) and the mixotrophic protistan Cryptomonas ovata developed faster and survived better than larvae that were fed other monotypic diets. Survival to adulthood of larvae fed several concentrations of the diatom Planothidium (=Achnanthes) lanceolatum was poor (1% C20 polyunsaturated fatty acids as total fat, but regardless of essential fatty acid content, algae that produced mucilage and filaments that sank out of the feeding zone were poor quality diets.

  9. Uncoupling of complex regulatory patterning during evolution of larval development in echinoderms

    Directory of Open Access Journals (Sweden)

    Jennings Charlotte K

    2010-11-01

    Full Text Available Abstract Background Conservation of orthologous regulatory gene expression domains, especially along the neuroectodermal anterior-posterior axis, in animals as disparate as flies and vertebrates suggests that common patterning mechanisms have been conserved since the base of Bilateria. The homology of axial patterning is far less clear for the many marine animals that undergo a radical transformation in body plan during metamorphosis. The embryos of these animals are microscopic, feeding within the plankton until they metamorphose into their adult forms. Results We describe here the localization of 14 transcription factors within the ectoderm during early embryogenesis in Patiria miniata, a sea star with an indirectly developing planktonic bipinnaria larva. We find that the animal-vegetal axis of this very simple embryo is surprisingly well patterned. Furthermore, the patterning that we observe throughout the ectoderm generally corresponds to that of "head/anterior brain" patterning known for hemichordates and vertebrates, which share a common ancestor with the sea star. While we suggest here that aspects of head/anterior brain patterning are generally conserved, we show that another suite of genes involved in retinal determination is absent from the ectoderm of these echinoderms and instead operates within the mesoderm. Conclusions Our findings therefore extend, for the first time, evidence of a conserved axial pattering to echinoderm embryos exhibiting maximal indirect development. The dissociation of head/anterior brain patterning from "retinal specification" in echinoderm blastulae might reflect modular changes to a developmental gene regulatory network within the ectoderm that facilitates the evolution of these microscopic larvae.

  10. Larval development of Notolopas brasiliensis Miers, 1886 (Brachyura: Majoidea: Pisidae described from laboratory reared material and a reappraisal of the characters of Pisidae

    Directory of Open Access Journals (Sweden)

    William Santana

    2006-01-01

    Full Text Available The complete larval stages of Notolopas brasiliensis are described from laboratory reared material, with emphasis on the external morphological features of Majoidea, and compare the morphology of N. brasiliensis with other genera of Pisidae. Larval development of N. brasiliensis consists of two zoeal stages and one megalopa. The duration mean of each zoeal stage was 4.2 ± 1.0 days for Zoea I and 3.8 ± 0.7 days for Zoea II, the megalopa instar appearing 8.1 ± 0.4 days after hatching. The characters previously used to define larval forms of Pisidae are either symplesiomorphic or potentially highly homoplastic. As well, was observed that there are no common sets of larval characters that would define Pisidae nowadays. However, was showed that only a combination of characters could differentiate Notolopas from other pisid genera.O completo desenvolvimento larval de Notolopas brasiliensis é descrito, a partir de material criado em laboratório, com ênfase na morfologia externa de Majoidea e comparado aos demais gêneros de Pisidae. O desenvolvimento larval de N. brasiliensis consiste em dois estágios de zoea e um de megalopa. A duração media de cada estágio foi de 4.2 ± 1.0 dias para a Zoea I e 3.8 ± 0.7 dias para a Zoea II, a megalopa aparece entre 8.1 ± 0.4 dias após a eclosão. Os caracteres previamente utilizados para definir as formas larvais de Pisidae ou são simplesiomórficos ou altamente homoplásticos. Foi observado que não existe um conjunto de caracteres capazes de definir Pisidae até o presente.Contudo foi mostrado que uma combinação de caracteres pode ser utilizada para diferenciar Notolopas dos demais gêneros da família.

  11. Light impacts embryonic and early larval development of the European eel, Anguilla anguilla

    DEFF Research Database (Denmark)

    Politis, Sebastian Nikitas; Butts, Ian; Tomkiewicz, Jonna

    2014-01-01

    intensity white (full spectrum, 10.5 μmol m-2 s-1), blue (~470 nm, 3.9 μmol m-2 s-1), green (~530 nm, 1.5 μmol m-2 s-1), and red light (~690 nm, 1.1 μmol m-2 s-1). Additionally, offspring were reared in continuous darkness (0:24 h light/dark). Results showed that light critically influenced early life...... in the 24:0 h light/dark photoperiod (13 ± 8%), and larvae reared in red light (22 ± 8%) had higher survival than those reared in green (14 ± 8%) or white light (11 ± 8%). Under continuous darkness, development and survival of offspring was as high as the best intensity-photoperiod-spectral composition......Little is known about the natural ecology of European eel during early life history. Weextend our understandings on the ecology of this species by studying howearly life stages perform under various light regimes.We assessed the effects of intensity, photoperiod (12:12 and 24:0 h light...

  12. Control of larval and egg development in Aedes aegypti with Ribonucleic acid interference (RNAi) against juvenile hormone acid methyl transferase

    Science.gov (United States)

    Ribonucleic acid interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including mosquitoes and many other insects. Little has been done, however, to harness this approach in order to control adult and larval mosquitoes. Juvenile hormone (JH) plays a pi...

  13. Effects of Sediment Containing Coal Ash from the Kingston Ash Release on Embryo-Larval Development in the Fathead Minnow, Pimephales promelas (Rafinesque, 1820)

    Energy Technology Data Exchange (ETDEWEB)

    Greeley Jr, Mark Stephen [ORNL; Elmore, Logan R [ORNL; McCracken, Kitty [ORNL; Sherrard, Rick [Tennessee Valley Authority (TVA)

    2014-01-01

    The largest environmental release of coal ash in U.S. history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority (TVA) Kingston Fossil Plant in East Tennessee. A byproduct of coal-burning power plants, coal ash is enriched in metals and metalloids such as selenium and arsenic with known toxicity to fish including embryonic and larval stages. The effects of contact exposure to sediments containing up to 78 % coal ash from the Kingston spill on the early development of fish embryos and larvae were examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed on hatching success, incidences of gross developmental abnormalities, or embryo-larval survival. Results suggest that direct exposures to sediment containing residual coal ash from the Kingston ash release may not present significant risks to fish eggs and larvae in waterways affected by the spill.

  14. Embryonic and larval development of Eugerres mexicanus (Perciformes: Gerreidae in Tenosique: Tabasco, Mexico

    Directory of Open Access Journals (Sweden)

    Raúl E Hernández

    2012-03-01

    Full Text Available Most studies on Eugerres mexicanus mainly consider biogeographic and systematic aspects and rarely address reproductive characteristics, which are useful for fishery population management plans. This study aimed at evaluating the ontogeny of E. mexicanus, based on 30 embryos and 30 larvae sampled by induced spawning of breeders, taken in February 2009 from the Usumacinta River in Tenosique, Tabasco, Mexico. All descriptions of the embryonic development were based on morphometric and meristic data and followed standard methods. Eggs, recovered at the gastrula stage, had an average diameter of 1.17mm (SD=0.08. The bud stage appeared during the first three hours of development, in which the posterior side was adhered to the vitellus; Kupffer´s vesicle was visible. Yolk-sac larvae hatched 18 hours after fertilization, exhibiting a light brown color and an average total length of 2.94mm (SD=0.70; the preflexion stage was reached eight days after hatching, with a total average length of 4.67mm (SD=0.50 and a total notochord length of 4.45mm (SD=0.50. The flexion stage was reached on the 16th day, with an average total length of 6.66mm (SD=1.53, while postflexion was reached on the 24th day, with 10.33mm (SD=1.45. The pre-juvenile stage was reached on the 33rd day, with a total length of 14.30mm (SD=0.93, showing IX spines and 10 rays and III spines and eight rays in the dorsal and anal fins, respectively. The juvenile stage was reached by the 45th day, with an average length of 28.16mm (SD=1.93 and average weight of 4.75g (SD=1.49. Prejuveniles showed an initial pigmentation with dark colored dots in the superior and inferior jaw and dispersed on the head, while juveniles presented the same pigmentation pattern, decreasing towards the margin of the caudal peduncle. In conclusion, the embryonic developmental stages of E. mexicanus were typical for the Gerreidae group. However, their morphometric characters were slightly different since the diameter

  15. Interrenal and thyroid development in red drum (Sciaenops ocellatus): effects of nursery environment on larval growth and cortisol concentration during settlement.

    Science.gov (United States)

    Pérez-Domínguez, Rafael; Holt, G Joan

    2006-04-01

    Red drum settle into shallow seagrass meadows during the larval stage. Day-night cycles in these habitats result in marked diel temperature and dissolved oxygen (DO) cycles, and it is possible that extreme fluctuations influence endocrine development and growth of larvae. Here, we described red drum interrenal and thyroid ontogeny and determine responses to environmental stimuli with special emphasis on settlement to explore possible role of hormones as mediator of directive environmental factors. This study detected an early activation of thyroid and interrenal axis during the yolk-sac phase and a second activation of the thyroid starting at settlement size to the end of the larval period. Whole-body l-thyroxine (T4) and 3-5-3'-triiodo-l-thyronine (T3) showed a sharp decline at the juvenile stage. In contrast, cortisol steadily declines during the larval phase to a minimum before the end of the larval period. Older settlement-size larvae exposed to a strong stimulus increased whole body cortisol. In contrast, new settlers showed a minor cortisol rise suggesting changes on stress responsiveness during the ontogeny of the species. Additionally, settlement-size larvae exposed to various environmentally realistic temperature or DO fluctuations showed no difference in growth compared to fish grown under stable conditions (control). However, growth rate was significantly reduced in DO cycled fish with prolonged exposure to hypoxia. No differences were found in whole-body cortisol levels in the reduced growth treatment groups, suggesting that growth retardation was not related to a cortisol-mediated stress response. In moderate DO and temperature treatment groups, cortisol showed wider fluctuations than control groups during the night time that were not related to stress.

  16. Evaluation of the nutritional quality of Chaetoceros muelleri Schütt (Chaetocerotales: Chaetocerotaceae and Isochrysis sp. (Isochrysidales: isochrysidaceae grown outdoors for the larval development of Litopenaeus vannamei (Boone, 1931 (Decapoda: Penaeidae

    Directory of Open Access Journals (Sweden)

    Rodríguez Erika O.

    2012-01-01

    Full Text Available The biomass, proximal composition and fatty acid profile of Isochrysis sp., Chaetoceros muelleri and their mixture, grown under greenhouse conditions, were evaluated. The nutritional value of both species supplied as the monoalgal (Chaetoceros muelleri: Diet I, and Isochrysis sp. Diet II and mixed diet (Diet III for larval Litopenaeus vannamei was also assessed on the basis of the development and biochemical composition of the larvae. The highest protein levels were obtained in Diets I and II (40% and 35%, respectively. No significant differences in larval survival were found among the diets; however, larvae fed on Diet II had the lowest mean larval length.

  17. Development of the larval amphibian growth and development assay: Effects of chronic 4-tert-octylphenol or 17ß-trenbolone exposure in Xenopus laevis from embryo to juvenile

    Science.gov (United States)

    The Larval Amphibian Growth and Development Assay (LAGDA) is a Tier II test guideline being developed by the US Environmental Protection Agency under the Endocrine Disruptor Screening Program. The LAGDA was designed to evaluate effects of chronic chemical exposure on growth, thy...

  18. Predator-induced larval cloning in the sand dollar Dendraster excentricus: might mothers matter?

    Science.gov (United States)

    Vaughn, Dawn

    2009-10-01

    Predator-induced cloning in echinoid larvae, with reduced size a consequence of cloning, is a dramatic modification of development and a novel response to risks associated with prolonged planktonic development. Recent laboratory studies demonstrate that exposure to stimuli from predators (i.e., fish mucus) induces cloning in the pluteus larvae (plutei) of Dendraster excentricus. However, the timing and incidence of cloning and size reduction of unrelated conspecific plutei differed across experiments. A variable cloning response suggests the effects of such factors as cue quality, egg provisioning, maternal experience, and genetic background, indicating that the potential advantages of cloning as an adaptive response to predators are not available to all larvae. This study tested the hypothesis that cloning in D. excentricus plutei is maternally influenced. Plutei from three half-sibling larval families (different mothers, same father) were exposed to fish mucus for 9 days during early development. Cloning was inferred in a percentage of plutei from each family; however, the rate and success of cloning differed significantly among the larval half-siblings. Unexpectedly, all mucus-treated plutei were smaller and developmentally delayed when compared to all plutei reared in the absence of a mucus stimulus. Thus, while the results from this study support the hypothesis of an influence of mothers on cloning of larval offspring, reduced larval size was a uniform response to fish mucus and did not indicate an effect of mothers. Hypotheses of the developmental effects of fish mucus on larval size with or without successful cloning are discussed.

  19. Development of a High Power Programmable Precise Time-Delay Trigger/Ignition System for MFCG

    Institute of Scientific and Technical Information of China (English)

    WU Bi; HE Yuan-hang; ZHANG Qing-ming; MA Yue-fen

    2008-01-01

    High-power precise delay trigger/ignition system is a programmable pulse generator developed for experiment controlling in explosively driven magnetic flux compression generators.Precise delay pulses are generated by the digital circuit,after being magnified and sharpened through multistage isolated amplifiers and rising edge sharpening device,high-voltage steep delay pulses with precision less than us level are obtained.This system has been used in our compact magnetic flux compression generator experiments in place of the traditional primaeord delay device.

  20. Embrionary and larval development of the marine clam Tivela mactroides (Bivalvia:Veneridaein Zulia State,Venezuela

    Directory of Open Access Journals (Sweden)

    Yinett M Reverol

    2004-12-01

    Full Text Available The marine clam,Tivela mactroides ,from Caño Sagua beach,Venezuela,was spawned and reared under laboratory conditions to monitor its early development.Spawning was spontaneous but in some cases it had to be induced by the additon of eggs and sperm.After fertilization,the embryonic development occurred at 5 hr approximately. Trochophore larvae were observed between eight and ten hours later.Straight-hinged veliger stage appeared 15 hr after fertilization.Transition from veliger stage to the umbo stage occurred about eight days after fertilization.Pediveliger stage was observed 22 days after fertilization.Metamorphosis of T.mactroides was not successful under our laboratory conditions;probably the bacterial contamination and subsequent mortalities were important factors constraining the final phase of the larval cycle.However,in a few cases young individuals were observed.We suspect that this was due to unfavorable conditions (e.g.:bacterial contamination, unsuitable food availability,etc.and the broad variation in developmental times,suggesting that these stages might be particularly sensitive to environmental changes.These results may not necessarily reflect what happens under natural conditions.Rev.Biol.Trop.52(4:903-909.Epub 2005 Jun 24.La almeja Tivela mactroides ,de la playa Caño Sagua, Venezuela,fue desovada y cultivada bajo condiciones de laboratorio,monitoreando su desarrollo embrionario y larvario.El desove fue espontáneo,sin embargo,en algunos casos se indujo adicionando óvulos y espermatozoides. El desarrollo embrionario se produjo en cinco horas, aproximadamente.La larva trocófora fue observada a las diez horas,mientras que la prodisoconcha aparece a las 15 horas después de la fertilización.La larva disoconcha aparece ocho días después de la fecundación y la veliconcha,aproximadamente a los 20 días.La metamorfosis de T.mactroides no fue satisfactoria bajo estas condiciones, ya que la contaminación bacterial fue uno de los

  1. CO2 induced seawater acidification impacts sea urchin larval development II: gene expression patterns in pluteus larvae.

    Science.gov (United States)

    Stumpp, M; Dupont, S; Thorndyke, M C; Melzner, F

    2011-11-01

    Extensive use of fossil fuels is leading to increasing CO(2) concentrations in the atmosphere and causes changes in the carbonate chemistry of the oceans which represents a major sink for anthropogenic CO(2). As a result, the oceans' surface pH is expected to decrease by ca. 0.4 units by the year 2100, a major change with potentially negative consequences for some marine species. Because of their carbonate skeleton, sea urchins and their larval stages are regarded as likely to be one of the more sensitive taxa. In order to investigate sensitivity of pre-feeding (2 days post-fertilization) and feeding (4 and 7 days post-fertilization) pluteus larvae, we raised Strongylocentrotus purpuratus embryos in control (pH 8.1 and pCO(2) 41 Pa e.g. 399 μatm) and CO(2) acidified seawater with pH of 7.7 (pCO(2) 134 Pa e.g. 1318 μatm) and investigated growth, calcification and survival. At three time points (day 2, day 4 and day 7 post-fertilization), we measured the expression of 26 representative genes important for metabolism, calcification and ion regulation using RT-qPCR. After one week of development, we observed a significant difference in growth. Maximum differences in size were detected at day 4 (ca. 10% reduction in body length). A comparison of gene expression patterns using PCA and ANOSIM clearly distinguished between the different age groups (two-way ANOSIM: Global R=1) while acidification effects were less pronounced (Global R=0.518). Significant differences in gene expression patterns (ANOSIM R=0.938, SIMPER: 4.3% difference) were also detected at day 4 leading to the hypothesis that differences between CO(2) treatments could reflect patterns of expression seen in control experiments of a younger larva and thus a developmental artifact rather than a direct CO(2) effect. We found an up regulation of metabolic genes (between 10%and 20% in ATP-synthase, citrate synthase, pyruvate kinase and thiolase at day 4) and down regulation of calcification related genes

  2. Early-born neurons in type II neuroblast lineages establish a larval primordium and integrate into adult circuitry during central complex development in Drosophila.

    Science.gov (United States)

    Riebli, Nadia; Viktorin, Gudrun; Reichert, Heinrich

    2013-04-23

    The central complex is a multimodal information-processing center in the insect brain composed of thousands of neurons representing more than 50 neural types arranged in a stereotyped modular neuroarchitecture. In Drosophila, the development of the central complex begins in the larval stages when immature structures termed primordia are formed. However, the identity and origin of the neurons that form these primordia and, hence, the fate of these neurons during subsequent metamorphosis and in the adult brain, are unknown. Here, we used two pointed-Gal4 lines to identify the neural cells that form the primordium of the fan-shaped body, a major component of the Drosophila central complex. We found that these early-born primordium neurons are generated by four identified type II neuroblasts that amplify neurogenesis through intermediate progenitors, and we demonstrate that these neurons generate the fan-shaped body primordium during larval development in a highly specific manner. Moreover, we characterize the extensive growth and differentiation that these early-born primordium neurons undergo during metamorphosis in pupal stages and show that these neurons persist in the adult central complex, where they manifest layer-specific innervation of the mature fan-shaped body. Taken together, these findings indicate that early-born neurons from type II neuroblast lineages have dual roles in the development of a complex brain neuropile. During larval stages they contribute to the formation of a specific central complex primordium; during subsequent pupal development they undergo extensive growth and differentiation and integrate into the modular circuitry of the adult brain central complex.

  3. Embryonic development and larval stages of Steindachneridion parahybae (Siluriformes: Pimelodidae: implications for the conservation and rearing of this endangered Neotropical species

    Directory of Open Access Journals (Sweden)

    Renato M. Honji

    2012-01-01

    Full Text Available Steindachneridion parahybae is a freshwater catfish endemic to the Paraíba do Sul River and is classified as an endangered Neotropical species. An increasing number of conservation biologists are incorporating morphological and physiological research data to help conservation managers in rescue these endangered species. This study investigated the embryonic and larval development of S. parahybae in captivity, with emphasis in major events during the ontogeny of S. parahybae. Broodstocks were artificially induced to reproduce, and the extrusion occurred 200-255 degree-hours after hormonal induction at 24°C. Larval ontogeny was evaluated every 10 minutes under microscopic/stereomicroscopic using fresh eggs samples. The main embryogenic development stages were identified: zygote, cleavage, including the morula, blastula, gastrula phase, organogenesis, and hatching. The extruded oocytes showed an average diameter of 1.10 ± 0.10 mm, and after fertilization and hydration of eggs, the average diameter of eggs increased to about 1.90 ± 0.60 mm, characterized by a large perivitelline space that persisted up to embryo development, the double chorion, and the poles (animal and vegetative. Cell division started about 2 minutes after fertilization (AF, resulting in 2, 4, 8 (4 x 2 arrangement of cells, 16 (4 x 4, 32 (4 x 8 and 64 (2 x 4 x 8 cells. Furthermore, the blastula and gastrula stages followed after these cells divisions. The closed blastopore occurred at 11 h 20 min AF; following the development, the organogenetic stages were identified and subdivided respectively in: early segmentation phase and late segmentation phase. In the early segmentation phase, there was the establishment of the embryonic axis, and it was possible to distinguish between the cephalic and caudal regions; somites, and the optic vesicles developed about 20 h AF. Total hatching occurred at 54 h AF, and the larvae average length was 4.30 ± 0.70 mm. Gradual yolk sac reduction

  4. Larval development sites of the main Culicoides species (Diptera: Ceratopogonidae) in northern Europe and distribution of coprophilic species larvae in Belgian pastures.

    Science.gov (United States)

    Zimmer, Jean-Yves; Brostaux, Yves; Haubruge, Eric; Francis, Frédéric

    2014-10-15

    Some Culicoides species of biting midges (Diptera: Ceratopogonidae) are biological virus vectors worldwide and have indeed been associated with outbreaks of important epizoonoses in recent years, such as bluetongue and Schmallenberg disease in northern Europe. These diseases, which affect domestic and wild ruminants, have caused considerable economic losses. Knowledge of substrates suitable for Culicoides larval development is important, particularly for the main vector temperate species. This study, realized during two years, aimed to highlight the larval development sites of these biting midge species in the immediate surroundings of ten Belgian cattle farms. Moreover, spatial distribution of the coprophilic Culicoides larvae (C. chiopterus and C. dewulfi) within pastures was studied with increasing distance from farms along linear transects (farm-pasture-woodland). A total of 4347 adult specimens belonging to 13 Culicoides species were obtained by incubation of 2131 soil samples belonging to 102 different substrates; 18 of these substrates were suitable for larval development. The Obsoletus complex (formed by two species) was observed in a wide range of substrates, including silage residues, components of a chicken coop, dung adhering to walls inside stables, leftover feed along the feed bunk, a compost pile of sugar beet residues, soil of a livestock trampling area, and decaying wood, while the following served as substrates for the other specimens: C. chiopterus, mainly cow dung; C. dewulfi, cow dung and molehill soil; C. circumscriptus, algae; C. festivipennis, algae and soil in stagnant water; C. nubeculosus, algae and silt specifically from the edge of a pond; C. punctatus, mainly wet soil between silage reserves; C. salinarius, algae; and C. stigma, algae and wet soil between silage reserves. We also recorded significantly higher densities of coprophilic larvae within pastures in cow dung located near forests, which is likely due to the localization of

  5. Leaf development and photosynthetic properties of three tropical tree species with delayed greening

    NARCIS (Netherlands)

    Cai, Z.Q.; Slot, M.; Fan, Z.X.

    2005-01-01

    Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in d

  6. Larval development and metamorphosis in Balanus amphitrite Darwin (Cirripedia; Thoracica): Significance of food concentration, temperature and nucleic acids

    Digital Repository Service at National Institute of Oceanography (India)

    Anil, A.C.; Desai, D.V.; Khandeparker, L.

    an individual’s chance of locating a site appropriate for metamorphosis, but simultane- ously reducing the ability to compete for space during the first few weeks of juvenile life. The cypris larvae are non-feeding and have to depend upon the energy reserves... barnacles to compete for space and seriously reduce their likelihood of successfully recruiting to the adult population. In Ž. Ž. the light of these observations, Jarrett and Pechenik 1997 and Pechenik et al. 1998 opined that larval experience influences...

  7. Of tests, trochs, shells, and spicules: Development of the basal mollusk Wirenia argentea (Solenogastres and its bearing on the evolution of trochozoan larval key features

    Directory of Open Access Journals (Sweden)

    Wanninger Andreas

    2010-01-01

    Full Text Available Abstract Background The phylogenetic status of the aplacophoran mollusk taxon Solenogastres (Neomeniomorpha is controversially discussed. Some authors propose the clade to represent the most basal branch within Mollusca, while others claim aplacophoran mollusks (Solenogastres and Caudofoveata to be derived. Larval characters are central in these discussions, specifically the larval test (calymma, apical cap, the ontogeny of the epidermal scleritome, and the proposed absence of larval protonephridia. To date, developmental data are available for five solenogaster species, but most reports are incomplete and need confirmation. Results Wirenia argentea deposit small batches of uncleaved embryos that are tightly enclosed by a smooth and transparent egg hull. Cleavage is spiral and unequal. The ciliated larvae hatch about 45 hours after deposition and swim actively in the water column. Within 48-60 hours after hatching they become mushroom-shaped with a pronounced apical cap partly enclosing a posterior trunk. The cells covering the apical cap are large and cleavage arrested. On the apical cap there is a prominent prototrochal band of compound cilia and an apical ciliary tuft and the trunk bears a terminal ciliary band (telotroch. Obscured by the apical cap, a ciliary band originates in the stomodaeal pore and surrounds the trunk. As development is proceeding, the trunk elongates and becomes covered by cuticle with the exception of a ventral ciliary band, the future foot. The larvae have a pair of protonephridia. At 5 days after hatching they begin to settle and within the following 7-9 days the apical cap is gradually reduced. Scattered epidermal sclerites form under the cuticle. Wirenia argentea lack iterated groups of sclerites at any developmental stage. At 40 days after hatching, the postlarvae have a fully developed foregut, but the midgut and hindgut are not yet interconnected. Conclusions Solenogastres develop via a trochophore

  8. Attention and Word Learning in Autistic, Language Delayed and Typically Developing Children

    Directory of Open Access Journals (Sweden)

    Elena eTenenbaum

    2014-05-01

    Full Text Available Previous work has demonstrated that patterns of social attention hold predictive value for language development in typically developing infants. The goal of this research was to explore how patterns of attention in autistic, language delayed, and typically developing children relate to early word learning and language abilities. We tracked patterns of eye movements to faces and objects while children watched videos of a woman teaching them a series of new words. Subsequent test trials measured participants’ recognition of these novel word-object pairings. Results indicated that greater attention to the speaker’s mouth was related to higher scores on standardized measures of language development for autistic and typically developing children (but not for language delayed children. This effect was mediated by age for typically developing, but not autistic children. When effects of age were controlled for, attention to the mouth among language delayed participants was negatively correlated with standardized measures of language learning. Attention to the speaker’s mouth and eyes while she was teaching the new words was also predictive of faster recognition of the newly learned words among autistic children. These results suggest that language delays among children with autism may be driven in part by aberrant social attention, and that the mechanisms underlying these delays may differ from those in language delayed participants without autism.

  9. Attention and word learning in autistic, language delayed and typically developing children.

    Science.gov (United States)

    Tenenbaum, Elena J; Amso, Dima; Abar, Beau; Sheinkopf, Stephen J

    2014-01-01

    Previous work has demonstrated that patterns of social attention hold predictive value for language development in typically developing infants. The goal of this research was to explore how patterns of attention in autistic, language delayed, and typically developing children relate to early word learning and language abilities. We tracked patterns of eye movements to faces and objects while children watched videos of a woman teaching them a series of new words. Subsequent test trials measured participants' recognition of these novel word-object pairings. Results indicated that greater attention to the speaker's mouth was related to higher scores on standardized measures of language development for autistic and typically developing children (but not for language delayed children). This effect was mediated by age for typically developing, but not autistic children. When effects of age were controlled for, attention to the mouth among language delayed participants was negatively correlated with standardized measures of language learning. Attention to the speaker's mouth and eyes while she was teaching the new words was also predictive of faster recognition of those words among autistic children. These results suggest that language delays among children with autism may be driven in part by aberrant social attention, and that the mechanisms underlying these delays may differ from those in language delayed participants without autism.

  10. Developmental and hormone-induced changes of mitochondrial electron transport chain enzyme activities during the last instar larval development of maize stem borer, Chilo partellus (Lepidoptera: Crambidae).

    Science.gov (United States)

    VenkatRao, V; Chaitanya, R K; Naresh Kumar, D; Bramhaiah, M; Dutta-Gupta, A

    2016-12-01

    The energy demand for structural remodelling in holometabolous insects is met by cellular mitochondria. Developmental and hormone-induced changes in the mitochondrial respiratory activity during insect metamorphosis are not well documented. The present study investigates activities of enzymes of mitochondrial electron transport chain (ETC) namely, NADH:ubiquinone oxidoreductase or complex I, Succinate: ubiquinone oxidoreductase or complex II, Ubiquinol:ferricytochrome c oxidoreductase or complex III, cytochrome c oxidase or complex IV and F1F0ATPase (ATPase), during Chilo partellus development. Further, the effect of juvenile hormone (JH) analog, methoprene, and brain and corpora-allata-corpora-cardiaca (CC-CA) homogenates that represent neurohormones, on the ETC enzyme activities was monitored. The enzymatic activities increased from penultimate to last larval stage and thereafter declined during pupal development with an exception of ATPase which showed high enzyme activity during last larval and pupal stages compared to the penultimate stage. JH analog, methoprene differentially modulated ETC enzyme activities. It stimulated complex I and IV enzyme activities, but did not alter the activities of complex II, III and ATPase. On the other hand, brain homogenate declined the ATPase activity while the injected CC-CA homogenate stimulated complex I and IV enzyme activities. Cumulatively, the present study is the first to show that mitochondrial ETC enzyme system is under hormone control, particularly of JH and neurohormones during insect development.

  11. Effects of temperature on embryonic and larval development and growth in the natterjack toad (Bufo calamita in a semi-arid zone

    Directory of Open Access Journals (Sweden)

    Sanuy, D.

    2008-06-01

    Full Text Available Temperature affects the duration of embryonic and larval periods in amphibians. Plasticity in time to metamorphosis is especially important in amphibian populations of Mediterranean semi-arid zones where temperatures are high and precipitation is low, increasing the rate of pond desiccation. In order to test the influence of water temperature on the larval development and growth of the natterjack toad (Bufo calamita, we collected two spawns in a semi¿arid zone at Balaguer (Lleida, NE Iberian peninsula. Approximately 50 (+/-10 eggs (stage 14-16 were raised in the lab at different temperature conditions: 10, 15, 20, 22.5 and 25ºC with 12:12 photoperiod. The results show a lengthening of development time with decreasing temperatures and a better survival performance of B. calamita to high temperatures. However, mean size at metamorphosis was not different across treatments, thus, suggesting that this population of B. calamita requires a minimum size to complete the metamorphosis. This study is the first approach to examine the effects that climatic factors have on the growth and development of B. calamita in semi-arid zones.

  12. Biochemical compounds' dynamics during larval development of the carpet-shell clam Ruditapes decussatus (Linnaeus, 1758): effects of mono-specific diets and starvation

    Science.gov (United States)

    Matias, Domitília; Joaquim, Sandra; Ramos, Margarete; Sobral, Paula; Leitão, Alexandra

    2011-09-01

    Successful larval growth and development of bivalves depend on energy derived from internal (endotrophic phase) and external (exotrophic phase) sources. The present paper studies survival, growth and biochemical changes in the early developmental stages (from egg to pediveliger) of the clam Ruditapes decussatus in order to characterize the nutritional requirements and the transition from the endotrophic to the exotrophic phase. Three different feeding regimes were applied: starvation and two mono-specific microalgal diets ( Isochrysis aff galbana and Chaetoceros calcitrans). A comparison between fed and unfed larvae highlighted the importance of egg lipid reserves, especially neutral lipids, during a brief endotrophic phase of embryonic development (first 2 days after fertilization). Egg reserves, however, may energetically contribute to the maintenance of larvae beyond the embryonic development. In fed larvae, the endotrophic phase is followed by a mixotrophic phase extending to days 5-8 after fertilization and a subsequent exotrophic phase. Metamorphosis starts around day 20. The intense embryonic activities are supported by energy derived from lipids, mainly from neutral lipids, and the metamorphic activities are supported by energy derived essentially from proteins accumulated during the planktonic phase and depend on the nutritional value of diets. The diet of I. aff galbana proves to be more adequate to R. decussatus larval rearing. The results provide useful information for the successful production of R. decussatus aquaculture.

  13. Defining the chronic impacts of atenolol on embryo-larval development and reproduction in the fathead minnow (Pimephales promelas).

    Science.gov (United States)

    Winter, Matthew J; Lillicrap, Adam D; Caunter, John E; Schaffner, Christian; Alder, Alfredo C; Ramil, Maria; Ternes, Thomas A; Giltrow, Emma; Sumpter, John P; Hutchinson, Thomas H

    2008-02-18

    Atenolol is a beta-adrenergic receptor antagonist ('beta-blocker') widely used for the treatment of angina, glaucoma, high blood pressure and other related conditions. Since atenolol is not appreciably metabolized in humans, the parent compound is the predominant excretory product, and has been detected in sewage effluent discharges and surface waters. Consequently, atenolol has been chosen as a reference pharmaceutical for a European Union-funded research consortium, known as ERAPharm (http://www.erapharm.org), which focused on the fate and effects of pharmaceuticals in the environment. Here, we present data generated within this project from studies assessing population-relevant effects in a freshwater fish species. Using fathead minnows (Pimephales promelas) as a standard OECD test species, embryo-larval development (early life stage or ELS) and short-term (21 d) adult reproduction studies were undertaken. In the ELS study, the 4d embryo NOEC(hatching) and LOEC(hatching) values were 10 and >10mg/L, respectively, and after 28 d, NOEC(growth) and LOEC(growth) values were 3.2 and 10mg/L, respectively (arithmetic mean measured atenolol concentrations were >90% of these nominal values). In the short-term reproduction study, NOEC(reproduction) and LOEC(reproduction) values were 10 and >10mg/L, respectively (mean measured concentrations were 77-96% of nominal values), while the most sensitive endpoint was an increase in male fish condition index, giving NOEC(condition index) and LOEC(condition index) values of 1.0 and 3.2mg/L, respectively. The corresponding measured plasma concentration of atenolol in these fish was 0.0518 mg/L. These data collectively suggest that atenolol has low chronic toxicity to fish under the conditions described, particularly considering the low environmental concentrations reported. These data also allowed the assessment of two theoretical approaches proposed as predictors of the environmental impact of human pharmaceuticals: the Huggett

  14. Ultrastructure of the ovary of Dermatobia hominis (Diptera: cuterebridae. I. Development during the 3rd larval instar

    Directory of Open Access Journals (Sweden)

    E. A. Gregorio

    1990-09-01

    Full Text Available The ultrastructure and distribution of gonial and somatic cells in the ovary of Dermatobia hominis was studied during the 3rd larval instar. In larvae weighing between 400 and 500 mg, the ovary is partially divided into basal and apical regions by oblong somatic cells that penetrate from the periphery; these cells show ovoid nucleus and cytoplasm full of microtubules. In both regions, gonial cells with regular outlines, large nucleus and low electron-density cytoplasm are scattered among the interstitial somatic cells. These later cells have small nucleus and electrodense cytoplasm. Clear somatic cells with small nucleus and cytoplasm of very low electron-density are restrict to the apical region of the gonad. Degenerating interstitial somatic cells are seen in the basal portion close to the ovary peduncle. During all this larval period the morphological features of the ovary remain almost the same. At the end of the period there is a gradual deposition of glycogen in the cytoplasm of the somatic cells, increase in the number and density of their mitochondria plus nuclear modification as membrane wrinkling and chromatin condensation in masses.

  15. Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.

    Science.gov (United States)

    Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

    2014-01-01

    We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements.

  16. An investigation of the factors affecting flatfoot in children with delayed motor development.

    Science.gov (United States)

    Chen, Kun-Chung; Tung, Li-Chen; Tung, Chien-Hung; Yeh, Chih-Jung; Yang, Jeng-Feng; Wang, Chun-Hou

    2014-03-01

    This study investigated the prevalence of flatfoot in children with delayed motor development and the relevant factors affecting it. In total, 121 preschool-aged children aged 3-6 with delayed motor development (male: 81; female: 40) were enrolled in the motor-developmentally delayed children group, and 4 times that number, a total of 484 children (male: 324; female: 160), of gender- and age-matched normal developmental children were used as a control group for further analyses. The age was from 3.0 to 6.9 years old for the participants. The judgment criterion of flatfoot was the Chippaux-Smirak index >62.70%, in footprint measurement. The results showed that the prevalence of flatfoot in children with motor developmental delay was higher than that in normal developmental children, approximately 58.7%, and that it decreased with age from 62.8% of 3-year-olds to 50.0% of 6-year-olds. The results also showed that motor-developmentally delayed children with flatfoot are at about 1.5 times the risk of normal developmental children (odds ratio=1.511, p=0.005). In addition, the prevalence of flatfoot is relatively higher in overweight children with delayed motor development, and that in obese children is even as high as 95.8% (23/24). Children with both excessive joint laxity and delayed development are more likely to suffer from flatfoot. The findings of this study can serve as a reference for clinical workers to deal with foot issues in children with delayed motor development.

  17. Nitric oxide affects ERK signaling through down-regulation of MAP kinase phosphatase levels during larval development of the ascidian Ciona intestinalis.

    Directory of Open Access Journals (Sweden)

    Immacolata Castellano

    Full Text Available In the ascidian Ciona intestinalis larval development and metamorphosis require a complex interplay of events, including nitric oxide (NO production, MAP kinases (ERK, JNK and caspase-3 activation. We have previously shown that NO levels affect the rate of metamorphosis, regulate caspase activity and promote an oxidative stress pathway, resulting in protein nitration. Here, we report that NO down-regulates MAP kinase phosphatases (mkps expression affecting positively ERK signaling. By pharmacological approach, we observed that the reduction of endogenous NO levels caused a decrease of ERK phosphorylation, whereas increasing levels of NO induced ERK activation. We have also identified the ERK gene network affected by NO, including mpk1, mpk3 and some key developmental genes by quantitative gene expression analysis. We demonstrate that NO induces an ERK-independent down-regulation of mkp1 and mkp3, responsible for maintaining the ERK phosphorylation levels necessary for transcription of key metamorphic genes, such as the hormone receptor rev-erb and the van willebrand protein vwa1c. These results add new insights into the role played by NO during larval development and metamorphosis in Ciona, highlighting the cross-talk between different signaling pathways.

  18. The influence of different salinity conditions on egg buoyancy and development and yolk sac larval survival and morphometric traits of Baltic Sea sprat (Sprattus sprattus balticus Schneider

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    Christoph Petereit

    2009-10-01

    Full Text Available The small pelagic sprat (Sprattus sprattus is a key ecologic player in the Baltic Sea. However, there is long-term variability in recruitment which is thought to be influenced by fluctuations in abiotic and biotic conditions experienced during the early life stages. This study concentrates on the influence of different ambient salinities on sprat egg development, egg buoyancy and survival as well as early yolk sac larval morphometric traits. Egg buoyancy significantly decreased with increasing salinity experienced during fertilization and/or incubation experiments. Field egg buoyancy measurements in 2007 and 2008 exhibited annual and seasonal differences in specific gravity, potentially associated with changes in adult sprat vertical distribution. Neither egg development time nor the duration of the yolk sac phase differed among salinity treatments. At eye pigmentation, larval standard length exhibited high variance among individuals but did not differ among treatments. The largest ecological impact of salinity experienced during spawning was the modification the buoyancy of eggs and yolk sac larvae, which determines their vertical habitat in the Baltic Sea. There are strong thermo- and oxyclines in the Baltic Sea, and thus salinity can indirectly impact the survival of these early life stages by modifying the ambient temperatures and oxygen conditions experienced.

  19. Development of delayed hydride cracking resistant-pressure tube

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Suk; Kwon, Sang Chul; Kim, S. S.; Yim, K. S

    2000-10-01

    For the first time, we demonstrate that the pattern of nucleation and growth of a DHC crack is governed by the precipitation of hydrides so that the DHC velocity and K{sub IH} are determined by an angle of the cracking plane and the hydride habit plane 10.7. Since texture controls the distribution of the 10.7 habit plane in Zr-2.5Nb pressure tube, we draw a conclusion that a textural change in Zr-2.5Nb tube from a strong tangential texture to the radial texture shall increase the threshold stress intensity factor, K{sub IH}, and decrease the delayed hydride cracking velocity. This conclusion is also verified by a complimentary experiment showing a linear dependence of DHCV and K{sub IH} with an increase in the basal component in the cracking plane. On the basis of the study on the DHC mechanism and the effect of manufacturing processes on the properties of Zr-2.5Nb tube, we have established a manufacturing procedure to make pressure tubes with improved DHC resistance. The main features of the established manufacturing process consist in the two step-cold pilgering process and the intermediate heat treatment in the {alpha} + {beta} phase for Zr-2.5Nb alloy and in the {alpha} phase for Zr-1Nb-1.2Sn-0.4Fe alloy. The manufacturing of DHC resistant-pressure tubes of Zr-2.5Nb and Zr-1N-1.2Sn-0.4Fe was made in the ChMP zirconium plant in Russia under a joint research with Drs. Nikulina and Markelov in VNIINM (Russia). Zr-2.5Nb pressure tube made with the established manufacturing process has met all the specification requirements put by KAERI. Chracterization tests have been jointly conducted by VNIINM and KAERI. As expected, the Zr-2.5Nb tube made with the established procedure has improved DHC resistance compared to that of CANDU Zr-2.5Nb pressure tube used currently. The measured DHC velocity of the Zr-2.5Nb tube meets the target value (DHCV <5x10{sup -8} m/s) and its other properties also were equivalent to those of the CANDU Zr-2.5Nb tube used currently. The Zr-1Nb-1

  20. An experimental field study of delayed density dependence in natural populations of Aedes albopictus.

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    Rachael K Walsh

    Full Text Available Aedes albopictus, a species known to transmit dengue and chikungunya viruses, is primarily a container-inhabiting mosquito. The potential for pathogen transmission by Ae. albopictus has increased our need to understand its ecology and population dynamics. Two parameters that we know little about are the impact of direct density-dependence and delayed density-dependence in the larval stage. The present study uses a manipulative experimental design, under field conditions, to understand the impact of delayed density dependence in a natural population of Ae. albopictus in Raleigh, North Carolina. Twenty liter buckets, divided in half prior to experimentation, placed in the field accumulated rainwater and detritus, providing oviposition and larval production sites for natural populations of Ae. albopictus. Two treatments, a larvae present and larvae absent treatment, were produced in each bucket. After five weeks all larvae were removed from both treatments and the buckets were covered with fine mesh cloth. Equal numbers of first instars were added to both treatments in every bucket. Pupae were collected daily and adults were frozen as they emerged. We found a significant impact of delayed density-dependence on larval survival, development time and adult body size in containers with high larval densities. Our results indicate that delayed density-dependence will have negative impacts on the mosquito population when larval densities are high enough to deplete accessible nutrients faster than the rate of natural food accumulation.

  1. Low testosterone correlates with delayed development in male orangutans.

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    Melissa Emery Thompson

    Full Text Available Male orangutans (Pongo spp. display an unusual characteristic for mammals in that some adult males advance quickly to full secondary sexual development while others can remain in an adolescent-like form for a decade or more past the age of sexual maturity. Remarkably little is understood about how and why differences in developmental timing occur. While fully-developed males are known to produce higher androgen levels than arrested males, the longer-term role of steroid hormones in male life history variation has not been examined. We examined variation in testosterone and cortisol production among 18 fully-developed ("flanged" male orangutans in U.S. captive facilities. Our study revealed that while testosterone levels did not vary significantly according to current age, housing condition, and species origin, males that had undergone precocious development had higher testosterone levels than males that had experienced developmental arrest. While androgen variation had previously been viewed as a state-dependent characteristic of male developmental status, our study reveals that differences in the physiology of early and late developing males are detectable long past the developmental transition and may instead be trait-level characteristics associated with a male's life history strategy. Further studies are needed to determine how early in life differences in testosterone levels emerge and what consequences this variation may have for male behavioral strategies.

  2. Effects of larval crowding on development time, survival and weight at metamorphosis in Aedes aegypti (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Arnaldo MACIÁ

    2009-01-01

    Full Text Available Los efectos del hacinamiento larval sobre el tiempo de desarrollo, la supervivencia y el peso en la metamorfosis fueron estudiados en el mosquito del dengue, Aedes aegypti L., en el laboratorio. Se criaron cohortes de larvas en 7 densidades (4, 8, 16, 32, 64, 128 y 256 larvas/ recipiente de 175 ml mientras se mantuvo constante el volumen de agua y la calidad y cantidad de alimento, bajo fotoperíodo y temperatura controlados. Se usaron detritos naturales, principalmente hojas, obtenidos de contenedores colonizados naturalmente por A. aegypti como fuente de nutrientes para las larvas. En cada densidad se registraron el tiempo de desarrollo, la mortalidad, el peso en la metamorfosis y la biomasa total. El tiempo de desarrollo varió entre 4 y 23 días en los machos, y 5 a 24 días en hembras; fue más prolongado a la densidad de 64 (en las hembras y 128 (en los machos larvas por recipiente. En densidades altas la proporción de sexos favoreció los machos. Hubo un incremento en la mortalidad en densidades iguales o mayores que 0,4 larvas/ ml (0,32 larvas/cm2. Se detectó una relación inversa entre la densidad larval y el peso de las pupas. La biomasa por individuo alcanzó un valor asintótico de aproximadamente 1 mg/individuo en una densidad de 128 individuos/ recipiente (0,64 larvas/cm2. Las poblaciones de A. aegypti, cercanas a su extremo sur de distribución, serían sensibles al hacinamiento en pequeños contenedores de agua.

  3. Speech development delay in a child with foetal alcohol syndrome

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2016-09-01

    Full Text Available A female foetus in her mother’s womb was exposed to high concentrations of alcohol at each stage of pregnancy on a long-term basis, which resulted in a permanent disability. In addition to a number of deficiencies in the overall functioning of the body of the child, there are serious problems pertaining to verbal communication. This thesis aims to describe foetal alcohol syndrome (FAS disease and present the basic problems with communication functions in a child, caused by damage of brain structures responsible for speech development. The thesis includes a speech diagnosis and therapy program adapted to the presented case. In the Discussion Section we have presented characteristics of communication disorders in case of children with FAS and the description of developmental malformations, neurobehavioral disorders, and environmental factors affecting the development of the child’s speech.

  4. Formulation, Development and Evaluation of delayed release capsules of Duloxetine Hydrochloride made of different Enteric Polymers

    Directory of Open Access Journals (Sweden)

    Pallavi Yerramsetty

    2012-03-01

    Full Text Available Delayed release systems have acquired a centre stage in the arena of pharmaceutical research and development. The present study involves formulation and evaluation of Duloxetine Hydrochloride delayed release capsules. Duloxetine Hydrochloride is an acid labile drug. It degrades in the acidic environment of the stomach thus leading to therapeutic inefficacy. Therefore it is necessary to bypass the acidic pH of the stomach which can be achieved by formulating delayed release dosage form by using different enteric polymers. Protection of drug from acidic environment is done by coating the drug with enteric polymers by using suspension layering technique in Fluidized bed processor (FBP with different enteric polymers like HPMCAS (Hydroxy Propyl Methyl Cellulose Acetate Succinate, Acryl EZE and HPMCP (Hydroxy propyl methyl cellulose phthalate.The formulation (E12 of delayed release capsules of Duloxetine Hydrochloride containing HPMCP (HP-55: HP- 50 as enteric polymer can be taken as optimized

  5. Studies on embryonic and larval development of sea cucumber (Holothuria scabra)%糙海参胚胎和幼体发育的形态观察

    Institute of Scientific and Technical Information of China (English)

    严俊贤; 王世锋; 周永灿; 朱彦博; 冯永勤

    2012-01-01

    为提高糙海参育苗技术,研究描述了糙海参从受精卵发育到稚参的形态变化,在显微镜下测定了受精卵、胚胎和幼体的大小,确定了糙海参胚胎发育的过程.结果表明,通过利用阴干、流水刺激法对成熟亲参进行人工催产,得到大量的受精卵,其受精率为90%以上.糙海参胚胎和幼体发育可分为受精卵、卵裂期、囊胚期、旋转囊胚期、原肠期、初耳状幼体、中耳状幼体、大耳状幼体、樽形幼体和稚参等阶段;在平均水温29℃,平均盐度34条件下,糙海参受精卵经3h发育形成囊胚,4h进入旋转囊胚期,5h进入原肠期,19h完成胚胎发育变态为耳状幼体;并经过7d的生长与发育进入樽形幼体;第15天变态为稚参.观察发现,多精入卵现象则会导致胚胎发育不正常,最终使胚胎发育停止并死亡.在糙海参幼体发育过程中,大耳状幼体期幼虫臂的大小及其球状体的形成均可作为判断其幼体发育健康状况的重要指标:幼虫臂越大,球状体出现率越高,其幼虫的变态率和成活率也越高.对比发现,位于糙海参尾部的突出结构——尾突,为仿刺参和新西兰刺参所没有,这一结构差异同时导致了其骨片位置也不同;并且,糙海参胚胎和幼体与其他种类的海参在发育时间上存在一定差异.%At present, the cultivation of sea cucumber in China is mainly concentrated in the north. The main rearing species is Apostichopus japonicu. However, in the southern part of China , the high temperature of water is not fit for the cultivation of A. japonicu. As a result, to meet market demand, developing the cultivation of tropical sea cucumber is very necessary. Holothuria scabra is one of common tropical sea cucumbers with high economic value in Hainan. In this thesis, to enhance the seeding technology of H. scabra, the embryonic and larval development of H. scabra was observed and recorded. The heights of fertilized eggs

  6. Larval fish nutrition

    National Research Council Canada - National Science Library

    Holt, J

    2011-01-01

    ... introduction to fish micronutrient history 4.2 Micronutrients in larval feeds 4.3 Requirements versus recommendations 4.4 Vitamins 4.5 Minerals 34.6 Future challenges Section 2: Nutritional Physi...

  7. Regional distribution of calretinin and calbindin-D28k expression in the brain of the urodele amphibian Pleurodeles waltl during embryonic and larval development.

    Science.gov (United States)

    Joven, Alberto; Morona, Ruth; Moreno, Nerea; González, Agustín

    2013-07-01

    The sequence of appearance of calretinin and calbindin-D28k immunoreactive (CRir and CBir, respectively) cells and fibers has been studied in the brain of the urodele amphibian Pleurodeles waltl. Embryonic, larval and juvenile stages were studied. The early expression and the dynamics of the distribution of CBir and CRir structures have been used as markers for developmental aspects of distinct neuronal populations, highlighting the accurate extent of many regions in the developing brain, not observed on the basis of cytoarchitecture alone. CR and, to a lesser extent, CB are expressed early in the central nervous system and show a progressively increasing expression from the embryonic stages throughout the larval life and, in general, the labeled structures in the developing brain retain their ability to express these proteins in the adult brain. The onset of CRir cells primarily served to follow the development of the olfactory bulbs, subpallium, thalamus, alar hypothalamus, mesencephalic tegmentum, and distinct cell populations in the rhombencephalic reticular formation. CBir cells highlighted the development of, among others, the pallidum, hypothalamus, dorsal habenula, midbrain tegmentum, cerebellum, and central gray of the rostral rhombencephalon. However, it was the relative and mostly segregated distribution of both proteins in distinct cell populations which evidenced the developing regionalization of the brain. The results have shown the usefulness in neuroanatomy of the analysis during development of the onset of CBir and CRir structures, but the comparison with previous data has shown extensive variability across vertebrate classes. Therefore, one should be cautious when comparing possible homologue structures across species only on the basis of the expression of these proteins, due to the variation of the content of calcium-binding proteins observed in well-established homologous regions in the brain of different vertebrates.

  8. Isolation and characterization of three mRNAs enriched in embryos of the direct-developing sea urchin Heliocidaris erythrogramma: evolution of larval ectoderm.

    Science.gov (United States)

    Haag, E S; Raff, R A

    1998-06-01

    The Australian sea urchin Heliocidaris erythro-gramma utilizes a derived direct developmental mode that evolved 8-12 million years ago. From a differential screen we have isolated a small set of cDNAs corresponding to genes more greatly expressed in embryos of H. erythrogramma than in those of its indirect-developing nearest relative, H. tuberculata. The method was biased towards abundant transcripts and did not allow detection of modifications of usage of highly conserved gene family members. Three differentially expressed abundant transcripts were found that potentially encode secreted proteins. Two of these, the arylsulfatase HeARS and the putative lectin HeEL-1, were identifiable as homologues of known proteins. Another gene, HeET-1, may be exclusively expressed in the H. erythrogramma embryo. In situ hybridization experiments demonstrate that all three transcripts are localized to the ectoderm. Two of them, HeET-1 and HeEL-1, are transcribed in an identical domain comprising the larval ectoderm. This region of gene expression has acquired a novel columnar cytology during the evolution of the H. erythrogramma embryo. The third sequence, HeARS, encodes an arylsulfatase homologue. Its expression is uniform in the gastrula, but as the rudiment develops it accumulates to the greatest extent in the invaginating vestibular ectoderm. Through comparisons with indirect-developing species, we show that this concentration of arylsulfatase mRNA in the rudiment is a novel feature of H. erythrogramma development. These data suggest that H. erythrogramma has a unique arrangement of ectodermal gene expression territories. We propose that these reflect larval adaptations that have occurred in the lineage leading to H. erythrogramma, and enabled the evolution of direct development.

  9. The effect of chicory ( Cichorium intybus ) and sulla ( Hedysarum coronarium ) on larval development and mucosal cell responses of growing lambs challenged with Teladorsagia circumcincta.

    Science.gov (United States)

    Tzamaloukas, O; Athanasiadou, S; Kyriazakis, I; Huntley, J F; Jackson, F

    2006-03-01

    The aim of this study was to investigate the effects of grazing different bioactive forages on acquired immunity against Teladorsagia circumcinta infection. The development of immunity was assessed by following the response of trickle-infected lambs grazing chicory (Cichorium intybus; IC), sulla (Hedysarum coronarium; IS) or grass/clover (Lolium perenne/Trifolium repens; IGC), to a single challenge infection. Parasite-naive lambs, grazing grass/clover, were also challenged with the single infection dose providing the uninfected control (UGC) group. Trickle infection significantly reduced worm establishment, inhibited larval development and increased mucosal mast cell (MMC) and globule leucocyte (GL) cells. Grazing treatment (chicory, sulla or grass/clover) significantly affected adult worm (Psulla or chicory compared to those grazing on grass/clover, probably due to differences in forage nutritional values.

  10. Effects of ambient temperature on egg and larval development of the invasive emerald ash borer (Coleoptera: Buprestidae): implications for laboratory rearing.

    Science.gov (United States)

    Duan, Jian J; Watt, Tim; Taylor, Phil; Larson, Kristi; Lelito, Jonathan P

    2013-10-01

    The emerald ash borer, Agrilus planipennis Fairmaire, an invasive beetle from Asia causing large scale ash (Fraxinus) mortality in North America, has been extremely difficult to rear in the laboratory because of its long life cycle and cryptic nature of immature stages. This lack of effective laboratory-rearing methods has not only hindered research into its biology and ecology, but also mass production of natural enemies for biological control of this invasive pest. Using sticks from the alternate host plant, Fraxinus uhdei (Wenzig) Lingelsh, we characterized the stage-specific development time and growth rate of both emerald ash borer eggs and larvae at different constant temperatures (12-35 degrees C) for the purpose of developing effective laboratory-rearing methods. Results from our study showed that the median time for egg hatching decreased from 20 d at 20 degrees C to 7 d at 35 degrees C, while no emerald ash borer eggs hatched at 12 degrees C. The developmental time for 50% of emerald ash borer larvae advancing to third, fourth, and J-larval stages at 20 degrees C were 8.3, 9.1, and 12.3 wk, respectively, approximately two times longer than at 30 degrees C for the corresponding instars or stages. In contrast to 30 degrees C, however, the development times of emerald ash borer larvae advancing to later instars (from oviposition) were significantly increased at 35 degrees C, indicating adverse effects of this high temperature. The optimal range of ambient temperature to rear emerald ash borer larvae should be between 25-30 degrees C; however, faster rate of egg and larval development should be expected as temperature increases within this range.

  11. Embryonic and larval development of Jundiá (Rhamdia quelen, Quoy & Gaimard, 1824, Pisces, Teleostei, a South American Catfish

    Directory of Open Access Journals (Sweden)

    C. R. Pereira

    Full Text Available The jundiá (Rhamdia quelen, Quoy & Gaimard is an endemic South American fish species. Because this species supports cold winters and grows faster during warm months, it has begun to be viewed as an ideal species for fish production in southern South America. In the present study, jundiá oocytes used were obtained by extrusion from females after hormone injection. Soon after hydration, the eggs were transferred to 50 L conic glass incubators, with constant and controlled water influx. Samples of fertilized eggs were transferred to Petri dishes and, examined under a stereoscopic microscope, were spherical, demersal, and non-adhesive with defined perivitelline space and resistant chorion. Cleavage stages occurred during the first 3.5 h. After hatching, larvae were transferred to 200 L glass fiber incubators. First signs of embryo movement were observed 21 h after fertilization; larval eclosion occurred 30.5 h after fertilization. Present findings may provide a basis for studies aimed at determining the complete ontogeny of jundiá and may be useful in eco-toxicological studies.

  12. First Record on Larval Development of the Cirripedian Parasite Loxothylacus texanus (Cirripedia-Rhizocephala Under Laboratory Conditions in Mxico

    Directory of Open Access Journals (Sweden)

    J. Franco-Lopez

    2006-01-01

    Full Text Available Crabs with mature parasites were put on individual aquariums of 20 L of capacity and with an initial salinity of 10. Salinity was gradually increased 1 until it reached a point in which parasites expeled their eggs or larvae. Larvae at different developmental stages obtained from each sample were preserved in 70 and ethanol to be studied afterwards. From 20 crabs employed, only 14 of them produced eggs and other 6 died after a few days at the aquariums. The mature externas expelled from 8000 to 160000 clustered eggs. After 24 h from the beginning of cellular division, larvae hatch. This larvae are called nauplius 1. This stage lasted 24 h, after which all larvae entered an excitation period, where they rapidly moved, to then pass a new molt process resulting in a new larval stage, nauplius 2. Elevating salinity a unity, externas started to expel eggs, nauplis larvae 1 hatched from them, but they only survived less than 24 h. As salinity increased, nauplius larvae lived longer, even to realized a molt. At a 15 salinity, larvae reached cypris stage with no problem, but with a salinity higher than 25, larvae died after a few hours of hatching. We can conclude that: the rhizocephalan Loxothylacus texanus has two nauplius stages, the nauplius and cypris larvae presented similar morphological characteristics to related species of rhizocephalans and a salinity interval from 15 to 20 report the same result.

  13. Radiographic study of delayed tooth development in patients with dental agenesis.

    Science.gov (United States)

    Ruiz-Mealin, Erika V; Parekh, Susan; Jones, Steven P; Moles, David R; Gill, Daljit S

    2012-03-01

    The aims of this study were to compare the radiographic development of permanent teeth in a group of children affected by dental agenesis with an unaffected control group and to determine the effects of confounding factors including the severity of the dental agenesis, age, sex, ethnicity, and the number of stages used to estimate dental age. A single-center retrospective cross-sectional study of dental panoramic tomographs was undertaken between July 2007 and April 2008 in a postgraduate teaching school. A total of 139 patients (aged 9-18 years) were recruited from the orthodontic clinic on the basis of predetermined inclusion and exclusion criteria to either a dental agenesis group or a control group. Dental panoramic tomograms were assessed, and the stages of development of the permanent teeth in the left maxillary and left mandibular regions were scored by using the 12 stages of Haavikko and the 8 stages of Demirjian and Goldstein. For each tooth scored, the mean dental age and standard error were determined by using the dental age assessment method, and an estimated dental age for each subject was derived by using the weighted average method. A statistically significant delay in dental age was found in the patients with dental agenesis compared with the control group. The dental age assessment method of Haavikko showed a delay of 1.20 years (SD, 1.74), and the method of Demirjian and Goldstein showed a delay of 1.64 years (SD, 1.75). It was also observed that older patients with dental agenesis had greater delays in tooth formation (P tooth, the dental age was delayed by 0.13 year (lower confidence interval, -0.22; upper confidence interval, 0.35). There was no evidence that sex or ethnicity has an effect on the delay in dental age in patients with dental agenesis. The development of permanent teeth in children with dental agenesis is delayed when compared with a matched control group. The severity of dental agenesis affected the magnitude of the delay (P <0

  14. Expression patterns of two heat-shock cognate 70 genes during immune responses and larval development of the Chinese mitten crab Eriocheir sinensis.

    Science.gov (United States)

    Li, P; Jiang, X F; Guo, W B; Yan, J; Zhou, K Y

    2016-09-16

    Two heat-shock protein (HSP) 70 family transcripts, heat-shock protein 70 cognate 5 and heat-shock protein 70 cognate 3 (designated as EsHSC70-5 and EsHSC70-3, respectively), were isolated from the Chinese mitten crab Eriocheir sinensis and their expression profiles were evaluated for their responsiveness to larval development and immune challenge in adult crabs. The HSPs exhibited 45-89% identity with other heat-shock proteins, and they shared similar structural features. EsHSC70 mRNA expression was detected not only during infection but also during the developmental larval stages. The EsHSC70s were enriched, and their expression fluctuated during early development. EsHSC70 mRNA expression was significantly induced by Vibrio parahaemolyticus challenge in all of the tissues studied (P < 0.05). Expression of EsHSC70 mRNA in the hepatopancreas and at the early zoeal stages was particularly pronounced, and the two EsHSC70s exhibited differential expression patterns both chronologically and spatially. The EsHSC70-5 mRNA level was significantly downregulated in the intestine and gills compared to that in controls at nearly all time points, and was expressed at a lower level after the bacterial challenge, indicating that EsHSC70-5 and EsHSC70-3 respond to immune challenges. The stage-specific enrichment of EsHSC70 transcripts in crabs suggests that these stress proteins play an essential role during brachyurization events.

  15. Attention and word learning in autistic, language delayed and typically developing children

    OpenAIRE

    Tenenbaum, Elena J.; Amso, Dima; Abar, Beau; Sheinkopf, Stephen J.

    2014-01-01

    Previous work has demonstrated that patterns of social attention hold predictive value for language development in typically developing infants. The goal of this research was to explore how patterns of attention in autistic, language delayed, and typically developing children relate to early word learning and language abilities. We tracked patterns of eye movements to faces and objects while children watched videos of a woman teaching them a series of new words. Subsequent test trials measure...

  16. Early Lexical Expression in Typically Developing Maltese Children: Implications for the Identification of Language Delay

    Science.gov (United States)

    Gatt, Daniela; Grech, Helen; Dodd, Barbara

    2013-01-01

    Limited word production may be the first indicator of impaired language development. The unavailability of normative data and standardized assessments for young Maltese children hinders the identification of early language delays. This study aimed to document Maltese children's expressive vocabulary growth and accompanying range of variation, to…

  17. Daytime Sleep Patterns in Preschool Children with Autism, Developmental Delay, and Typical Development

    Science.gov (United States)

    Schwichtenberg, A. J.; Iosif, Ana-Maria; Goodlin-Jones, Beth; Tang, Karen; Anders, Thomas

    2011-01-01

    The present study examined daytime sleep patterns in 3 groups of preschool-aged children: children with autism, children with developmental delay, and children who were developing typically. Sleep was assessed in 194 children via actigraphy and parent-report sleep diaries for 7 consecutive days on 3 separate occasions over 6 months. Children with…

  18. Sleep Patterns in Preschool-Age Children with Autism, Developmental Delay, and Typical Development

    Science.gov (United States)

    Goodlin-Jones, Beth L.; Tang, Karen; Liu, Jingyi; Anders, Thomas F.

    2008-01-01

    The study investigates sleep disorders by assessing the quantity and quality of sleep in preschool children with autism and comparing them with developmental delay without autism, and typical development. The results prove that sleep patterns are different in preschool children across all three categories.

  19. Delayed umbilical cord clamping for reducing anaemia in low birthweight infants : implications for developing countries

    NARCIS (Netherlands)

    van Rheenen, Patrick F.; Gruschke, Sebastian; Brabin, Bernard J.

    BACKGROUND: Cheap and effective interventions are needed to reduce the risk of infant anaemia in developing countries. Delayed cord clamping (DCC) has been shown to be a simple, safe and cost-free delivery procedure that augments red cell mass in appropriate-for-gestational-age term and preterm

  20. Frontostriatal white matter integrity predicts development of delay of gratification : A longitudinal study

    NARCIS (Netherlands)

    Achterberg, Michelle; Peper, Jiska S.; van Duijvenvoorde, Anna C K; Mandl, René C W; Crone, Eveline A.

    2016-01-01

    The ability to delay gratification increases considerably across development. Here, we test the hypothesis that this impulse control capacity is driven by increased maturation of frontostriatal circuitry using a fiber-tracking approach combined with longitudinal imaging. In total, 192 healthy volunt

  1. Early Lexical Expression in Typically Developing Maltese Children: Implications for the Identification of Language Delay

    Science.gov (United States)

    Gatt, Daniela; Grech, Helen; Dodd, Barbara

    2013-01-01

    Limited word production may be the first indicator of impaired language development. The unavailability of normative data and standardized assessments for young Maltese children hinders the identification of early language delays. This study aimed to document Maltese children's expressive vocabulary growth and accompanying range of variation, to…

  2. Effect of maize lines on larval fitness costs of Cry1F resistance in the European corn borer (Lepidoptera: Crambidae).

    Science.gov (United States)

    Petzold-Maxwell, Jennifer L; Siegfried, Blair D; Hellmich, Richard L; Abel, Craig A; Coates, Brad S; Spencer, Terrence A; Gassmann, Aaron J

    2014-04-01

    Crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted and enable management of key insect pests while reducing the use of conventional insecticides. However, the evolution of Bt resistance could diminish these benefits. Fitness costs of Bt resistance occur in the absence of Bt toxin when individuals with resistance alleles show a reduction in fitness relative to susceptible individuals, and they can delay the evolution of resistance. Ecological factors including host-plant variety can affect the magnitude of fitness costs, and consequently, the degree to which fitness costs delay resistance. In this study, we measured fitness costs of resistance to Bt toxin Cry1F in the European corn borer Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) using Cry1F-resistant and Cry1F-susceptible strains sharing a similar genetic background. Fitness costs were tested on three lines of maize, Zea mays L., by measuring larval survival and development in two greenhouse experiments with plants in either the vegetative or reproductive stage. Both experiments showed that maize line significantly affected larval survival and developmental rate. However, larval survival, mass, and developmental rate did not differ between the Cry1F-resistant and susceptible strains, indicating a lack of fitness costs of resistance to Cry1F for the larval fitness components measured in this experiment. Future experiments should test for fitness costs of Cry1F resistance affecting survival to adulthood and adult life-history parameters.

  3. Fasciola gigantica: the growth and larval productivity of redial generations in the snail Lymnaea truncatula.

    Science.gov (United States)

    Dar, Y; Vignoles, P; Rondelaud, D; Dreyfuss, G

    2002-04-01

    Bimiracidial infections of French Lymnaea truncatula with a Madagascan isolate of Fasciola gigantica were carried out under laboratory conditions to study the growth of rediae and their larval productivity in relation to the different redial generations. The total numbers of rediae and their mean lengths significantly increased with the duration of infection until day 49 post-exposure (p.e.). Significant differences in the lengths between the different redial generations were noted. At day 49 p.e. (at 20 degrees C), the cercariae were produced by the first redial generation, while the productivity of other redial groups was delayed. This last finding shows a slow larval development of this Madagascan isolate of F. gigantica in this French population of L. truncatula.

  4. Development of a Marx-coupled trigger generator with high voltages and low time delay

    Science.gov (United States)

    Hu, Yixiang; Zeng, Jiangtao; Sun, Fengju; Cong, Peitian; Su, Zhaofeng; Yang, Shi; Zhang, Xinjun; Qiu, Ai'ci

    2016-10-01

    Coupled by the Marx of the "JianGuang-I" facility, a high voltage, low time-delay trigger generator was developed. Working principles of this trigger generator and its key issues were described in detail. Structures of this generator were also carefully designed and optimized. Based on the "JianGuang-I" Marx generator, a test stand was established. And a series of experiment tests were carried out to the study performance of this trigger generator. Experiment results show that the output voltage of this trigger generator can be continuously adjusted from 58 kV to 384 kV. The time delay (from the beginning of the Marx-discharging pulse to the time that the output pulse of the trigger generator arises) of this trigger pulse is about 200 ns and its peak time (0%˜100%) is less than 50 ns. Experiment results also indicate that the time-delay jitter of trigger voltages decreases rapidly with the increase in the peak voltage of trigger pulses. When the trigger voltage is higher than 250 kV, the time-delay jitters (the standard deviation) are less than 7.7 ns.

  5. The attitudes of family physicians toward a child with delayed growth and development.

    Science.gov (United States)

    Aker, Servet; Şahin, Mustafa Kürşat; Kınalı, Ömer; Şimşek Karadağ, Elif; Korkmaz, Tuğba

    2017-09-01

    Aim The purpose of this study was to assess the attitude of family physicians toward a child with delayed growth and development. Primary healthcare professionals play a key role in monitoring growth and development, the best indicator of the child's health status. If delayed growth and development can be detected early, then it is usually possible to restore functioning. This descriptive study was performed in Samsun, Turkey, in May and June 2015. In total, 325 family physicians were included. The study consisted of two parts. In the first session of the research, the story of an 18-month-old child with delayed growth and development was presented using visual materials. An interview between the child's mother and a member of primary healthcare staff was then enacted by two of the authors using role-playing. Subsequently, participants were given the opportunity to ask the mother and member of primary healthcare staff questions about the case. During the sessions, two observers observed the participants, took notes and compared these after the presentation. In the second part of the study, the participants were asked to complete a questionnaire consisting of three open-ended questions. Findings When asking questions of the mother, family physicians generally used accusatory and judgmental language. One of the questions most commonly put to the mother was 'Do you think you are a good mother?' Family physicians were keen to provide instruction for the patient and relatives. Family physicians to a large extent thought that the problem of a child with delayed growth and development can be resolved through education. Family physicians' manner of establishing relations with the patient and relatives is inappropriate. We therefore think that they should receive on-going in-service training on the subject.

  6. [Delayed identity development, family relationships and psychopathology: Links between healthy and clinically disturbed youth].

    Science.gov (United States)

    Seiffge-Krenke, Inge; Escher, Fabian J

    2017-05-19

    This study compared three groups of various age and health status (total N = 732) with respect to their identity status, stress level, and parental behavior. As expected, patients were characterized by delayed identity development, particularly ruminative exploration. Further, patients experienced high identity stress and described high levels of anxious paternal rearing and intrusive maternal psychological control. The patients‘ levels of both internalizing and externalizing symptomatology were high, and the impact of externalizing symptoms on identity arrest was strong. Identity status was delayed, albeit age adequate in both groups of healthy youths, with comparably high levels of anxious parental monitoring. Compared to adolescents, young adults were particularly active in their identity development, showing a high level of identity stress but no increase in psychopathology.

  7. Embryonic and larval development of Babyloniaformosae habei (Altena and Gittenberger, 1981) (Gastropoda:Buccinidae) on China's coast

    Institute of Scientific and Technical Information of China (English)

    CHENYan; ZHOUShiqiang; LIFuxue

    2004-01-01

    The development of embryos and larvae of Babyloniaformosae habei living along the southeast coast of China is observed under laboratory conditions. The egg masses are laid by females on hard substrate at night and each capsule contains 100-500 eggs. Each egg is 250-280 mm in diameter. The fast two cleavages of the embryo are meridional and equal, and a polar lobe is produced. Larval kidney, which only consists of a single cell, appears during the gastrula stage on each side of the embryo. The right tentacle develops prior to the left one. At 25-27 ℃, an intracapsulate veliger stage is reached about 4.5 d after deposition. The larvae hatch on the fifth day as swimming veligers with a shell length of 360 -500 mm. The newly hatched larva can ingest suspended algal cells from the water column and remains in the pelagic stage for 8-10 d. The newly settled juveniles are 900-1 200 mm in shell length.

  8. Late snowmelt delays plant development and results in lower reproductive success in the High Arctic.

    Science.gov (United States)

    Cooper, Elisabeth J; Dullinger, Stefan; Semenchuk, Philipp

    2011-01-01

    In tundra areas where the growing season is short, any delay in the start of summer may have a considerable effect on plant development, growth and reproductive success. Climate models suggest long-term changes in winter precipitation in the Arctic, which may lead to deeper snow cover and a resultant delay in date of snow melt. In this paper, we investigated the role of snow depth and melt out date on the phenological development and reproductive success of vascular plants in Adventdalen, Svalbard (78° 10'N, 16° 06'E). Effects of natural variations in snow accumulation were demonstrated using two vegetation types (snow depth: meadow 21 cm, heath 32 cm), and fences were used to experimentally increase snow depth by over 1m. Phenological delay was greatest directly after snowmelt in the earlier phenological phases, and had the largest effect on the early development of those species which normally green-up early (i.e. Dryas, Papaver, Salix, Saxifraga). Compressed growing seasons and length of the reproductive period led to a reduced reproductive success in some of the study species. There were fewer flowers, fewer plots with dispersing seeds, and lower germination rates. This can have consequences for plant establishment and community composition in the long-term.

  9. Effects of music therapy in the treatment of children with delayed speech development - results of a pilot study

    OpenAIRE

    Linden Ulrike; Groß Wibke; Ostermann Thomas

    2010-01-01

    Abstract Background Language development is one of the most significant processes of early childhood development. Children with delayed speech development are more at risk of acquiring other cognitive, social-emotional, and school-related problems. Music therapy appears to facilitate speech development in children, even within a short period of time. The aim of this pilot study is to explore the effects of music therapy in children with delayed speech development. Methods A total of 18 childr...

  10. Influence of metal(loid) bioaccumulation and maternal transfer on embryo-larval development in fish exposed to a major coal ash spill.

    Science.gov (United States)

    Greeley, Mark S; Adams, S Marshall; Elmore, Logan R; McCracken, Mary K

    2016-04-01

    In December 2008, an earthen retaining wall at the Tennessee Valley Authority (TVA) Kingston Fossil Fuel Plant failed and released 4.1 millionm(3) of coal ash to rivers flowing into Watts Bar Reservoir in east Tennessee, United States (U.S.). As part of a comprehensive effort to evaluate the risks to aquatic resources from this spill - the largest in U.S. history - we compared bioaccumulation and maternal transfer of selenium (Se), arsenic (As), and mercury (Hg) in adult redear sunfish (Lepomis macrolophus), collected two years after the spill from both coal-ash exposed and non-exposed areas of the Emory and Clinch Rivers, with the success of embryo-larval development in their offspring. Whole body and ovary concentrations of Se in female sunfish at three study sites downstream of the spill were significantly elevated (site means=4.9-5.3 and 6.7-9.0mg/kg d.w. whole body and ovary concentrations, respectively) compared with concentrations in fish from reference sites upstream of the spill site (2.2-3.2mg/kg d.w. for whole bodies and 3.6-4.8mg/kg d.w. for ovaries). However, Se concentrations in coal ash-exposed areas remain below proposed U.S. Environmental Protection Agency (USEPA) criteria for the protection of aquatic life. Site-to-site variation in fish concentrations of As and Hg were not well-correlated with ash-exposure, reflecting the multiple sources of these metal(loid)s in the affected watersheds. In 7-day laboratory tests of embryos and larvae derived from in vitro crosses of eggs and sperm from these field-collected sunfish, fertilization success, hatching success, embryo-larval survival, and incidences of developmental abnormalities did not differ significantly between ash-exposed and non-exposed fish. Furthermore, these developmental endpoints were not correlated with whole body or ovary concentrations of Se, As, or Hg in the maternal fish, or with fish size, ovary weight, or gonadal-somatic indices. Results from this and related studies associated

  11. Differential expression of insulin-like growth factor I and II mRNAs during embryogenesis and early larval development in rabbitfish, Siganus guttatus.

    Science.gov (United States)

    Ayson, Felix G; de Jesus, Evelyn Grace T; Moriyama, Shunsuke; Hyodo, Susumu; Funkenstein, Bruria; Gertler, Arieh; Kawauchi, Hiroshi

    2002-04-01

    In rodents, the expression of insulin-like growth factor II (IGF-II) is higher than that of insulin-like growth factor I (IGF-I) during fetal life while the reverse is true after birth. We wanted to examine whether this is also true in fish and whether IGF-I and IGF-II are differentially regulated during different stages of embryogenesis and early larval development in rabbitfish. We first cloned the cDNAs of rabbitfish IGF-I and IGF-II from the liver. Rabbitfish IGF-I has an open reading frame of 558 bp that codes for a signal peptide of 44 amino acids (aa), a mature protein of 68 aa, and a single form of E domain of 74 aa. Rabbitfish IGF-II, on the other hand, has an open reading frame of 645 bp that codes for a signal peptide of 47 aa, a mature protein of 70 aa, and an E domain of 98 aa. On the amino acid level, rabbitfish IGF-I shares 68% similarity with IGF-II. We then examined the relative expression of the two IGFs in unfertilized eggs, during different stages of embryogenesis, and in early larval stages of rabbitfish by a semiquantitative reverse transcription-polymerase chain reaction. Primers that amplify the mature peptide region of both IGFs were used and PCR for both peptides was done simultaneously, with identical PCR conditions for both. The identity of the PCR products was confirmed by direct sequencing. Contrary to published reports for seabream and rainbow trout, IGF-I mRNA was not detected in rabbitfish unfertilized eggs; it was first expressed in larvae soon after hatching. IGF-II mRNA, however, was expressed in unfertilized eggs, albeit weakly, and was already strongly expressed during the cleavage stage. mRNAs for both peptides were strongly expressed in the larvae, although IGF-II mRNA expression was higher than IGF-I expression.

  12. Early developmental delay in children with autism: A study from a developing country.

    Science.gov (United States)

    Arabameri, Elahe; Sotoodeh, Mohammad Saber

    2015-05-01

    Early diagnosis is appropriate and important for developmental disorders such as autism spectrum disorder. In many less developed countries, unfortunately, diagnosis of this disorder is delayed. The aim of the present study is to determine whether this disorder can be screened using simple strategies such as comparison of the age of acquisition of motor skills. For this purpose, 124 children with autism were chosen to enter the study, and their parents were asked to retrospectively specify the age of achieving milestones of sitting without support, standing alone and walking alone. Information obtained from the parents was compared with World Health Organization standards. Results indicate that participants (male and female) have significantly delayed age of acquisition of all three skills. Based on this result, it can be suggested that existing standards, as a simple means with low cost and easy availability, can be used for early screening of the disease at a younger age so that treatment can be provided more quickly.

  13. Cognitive development in children with language impairment, and correlation between language and intelligence development in kindergarten children with developmental delay.

    Science.gov (United States)

    Liao, Su-Fen; Liu, Jui-Ching; Hsu, Chun-Ling; Chang, Ming-Yuh; Chang, Tung-Ming; Cheng, Helen

    2015-01-01

    We performed a retrospective review of 65 children with developmental delay. The male-to-female ratio was 2.25 : 1, and the mean age was 5.8 years; performance IQ was 94.8, verbal IQ was 83, and full-scale IQ was 87.4. Twenty-three (35%) children had normal language development, 13 (20%) had below average language development, and 29 (45%) had developmental language disorder. Performance IQ was significantly better than verbal IQ in all children (P children with developmental language disorder and specific language impairment was significantly lower than that of children with normal language development. Performance IQ was found to be correlated with language score (r = .309, P = .012). The children with language impairment were associated with lower IQ scores. The discrepancy between performance IQ and verbal IQ persisted in children with developmental delay, not only in children with language disorder. © The Author(s) 2014.

  14. Cofactor Independent Phosphoglycerate Mutase of Brugia malayi Induces a Mixed Th1/Th2 Type Immune Response and Inhibits Larval Development in the Host

    Directory of Open Access Journals (Sweden)

    Prashant K. Singh

    2014-01-01

    Full Text Available Lymphatic filariasis is a major debilitating disease, endemic in 72 countries putting more than 1.39 billion people at risk and 120 million are already infected. Despite the significant progress in chemotherapeutic advancements, there is still need for other measures like development of an effective vaccine or discovery of novel drug targets. In this study, structural and immunological characterization of independent phosphoglycerate mutase of filarial parasite Brugia malayi was carried out. Protein was found to be expressed in all major parasite life stages and as an excretory secretory product of adult parasites. Bm-iPGM also reacted to all the categories of human bancroftian patient’s sera including endemic normals. In vivo immunological behaviour of protein was determined in immunized BALB/c mice followed by prophylactic analysis in BALB/c mice and Mastomys coucha. Immunization with Bm-iPGM led to generation of a mixed Th1/Th2 type immune response offering 58.2% protection against larval challenge in BALB/c and 65–68% protection in M. coucha. In vitro studies confirmed participation of anti-Bm-iPGM antibodies in killing of B. malayi infective larvae and microfilariae through ADCC mechanism. The present findings reveal potential immunoprotective nature of Bm-iPGM advocating its worth as an antifilarial vaccine candidate.

  15. Transcriptome Analysis of Drosophila melanogaster Third Instar Larval Ring Glands Points to Novel Functions and Uncovers a Cytochrome p450 Required for Development

    Science.gov (United States)

    Christesen, Danielle; Yang, Ying Ting; Somers, Jason; Robin, Charles; Sztal, Tamar; Batterham, Philip; Perry, Trent

    2016-01-01

    In Drosophila melanogaster larvae, the ring gland (RG) is a control center that orchestrates major developmental transitions. It is a composite organ, consisting of the prothoracic gland, the corpus allatum, and the corpora cardiaca, each of which synthesizes and secretes a different hormone. Until now, the RG’s broader developmental roles beyond endocrine secretion have not been explored. RNA sequencing and analysis of a new transcriptome resource from D. melanogaster wandering third instar larval RGs has provided a fascinating insight into the diversity of developmental signaling in this organ. We have found strong enrichment of expression of two gene pathways not previously associated with the RG: immune response and fatty acid metabolism. We have also uncovered strong expression for many uncharacterized genes. Additionally, RNA interference against RG-enriched cytochrome p450s Cyp6u1 and Cyp6g2 produced a lethal ecdysone deficiency and a juvenile hormone deficiency, respectively, flagging a critical role for these genes in hormone synthesis. This transcriptome provides a valuable new resource for investigation of roles played by the RG in governing insect development. PMID:27974438

  16. Three metabolites from an entomopathogenic bacterium, Xenorhabdus nematophila, inhibit larval development of Spodoptera exigua (Lepidoptera: Noctuidae) by inhibiting a digestive enzyme, phospholipase A2

    Institute of Scientific and Technical Information of China (English)

    Jaehyun Kim; Yonggyun Kim

    2011-01-01

    An entomopathogenic bacterium, Xenorhabdus nematophila, has been known to induce significant immunosuppression of target insects by inhibiting immune-associated phospholipase A2 (PLA2), which subsequently shuts down biosynthesis of eicosanoids that are critical in immune mediation in insects. Some metabolites originated from the bacterial culture broth have been identified and include benzylideneacetone, proline-tyrosine and acetylated phenylalanine-glycine-valine, which are known to inhibit enzyme activity of PLA2 extracted from hemocyte and fat body. This study tested their effects on digestive PLA2 of the beet armyworm, Spodoptera exigua. Young larvae fed different concentrations of the three metabolites resulted in significant adverse effects on larval development even at doses below 100 μg/mL. In particular, they induced significant reduction in digestive efficiency of ingested food. All three metabolites significantly inhibited catalytic activity of digestive PLA2 extracted from midgut lumen of the fifth instar larvae at a low micromolar range. These results suggest that the inhibitory activities of the three bacterial metabolites on digestive PLA2 of S. exigua midgut may explain some of their oral toxic effects.

  17. Prorenin Receptor Homologue VHA-20 is Critical for Intestinal pH Regulation, Ion and Water Management and Larval Development in C. elegans.

    Science.gov (United States)

    Zima, V; Šebková, K; Šimečková, K; Dvořák, T; Saudek, V; Kostrouchová, M

    2015-01-01

    The prorenin receptor (ATP6AP2) is a multifunctional transmembrane protein; it is a constituent of proton-translocating V-ATPase, a non-proteolytic activator of renin and an adaptor in the Wnt/β-catenin pathway. Here, we studied vha-20, one of the two prorenin receptor homologues that are identified by sequence similarity in the C. elegans genome. We show that vha-20 (R03E1.2) is prominently expressed in the intestine, in the excretory cell and in amphid neurons, tissues critical for regulation of ion and water management. The expression of vha-20 in the intestine is dependent on NHR-31, a nuclear receptor related to HNF4. VHA-20 is indispensable for normal larval development, acidification of the intestine, and is required for nutrient uptake. Inhibition of vha-20 by RNAi leads to complex deterioration of water and pH gradients at the level of the whole organism including distention of pseudocoelome cavity. This suggests new roles of prorenin receptor in the regulation of body ion and water management and in acidification of intestinal lumen in nematodes.

  18. A new case of poecilogony from South America and the implications of nurse eggs, capsule structure, and maternal brooding behavior on the development of different larval types.

    Science.gov (United States)

    Oyarzun, Fernanda X; Brante, Antonio

    2015-04-01

    Poecilogony is the production of different larval types within the same species. Although rare, poecilogonous species are ideal systems for testing the evolutionary and ecological implication of different developmental modes in marine invertebrates. Here, we described a new case of poecilogony, the Southern Hemisphere spionid Boccardia wellingtonensis. We used a combination of common-garden experiments, video recordings, and in vitro manipulations of individuals from three sites to (1) document the type of poecilogony, the brooding behavior of the mother, and the hatching process; (2) experimentally measure the effect of nurse eggs on the growth and type of larvae produced; and (3) document variation in the length of the brooding period, number of capsules, larvae, and nurse eggs of mothers from three sites to explore the potential for plasticity in reproductive traits. These results were compared to the previously reported poecilogonous species B. proboscidea, which resembles B. wellingtonensis in size, morphology, ecology, and reproductive strategy but differs in capsule structure. We found that in contrast to B. proboscidea, B. wellingtonensis produced larvae that, in isolation and in the presence of nurse eggs, developed into a wide range of offspring sizes. Mothers brood and hatch the larvae with frequent partial hatching of the brood during the brooding period. Although larvae could not liberate themselves, larvae crossed to other capsules as interconnections between capsules broke during the developmental period, potentially affecting food availability, sibling competition for nurse eggs, and cannibalism. Variation in brooding time and number of capsules deposited among sites suggest local adaptations.

  19. Effects of cysteine proteinase inhibitors scN and E-64 on southern corn rootworm larval development

    Science.gov (United States)

    The southern corn rootworm (SCRW) can be a serious pest of peanut pods. A laboratory bioassay was developed to test feeding cysteine proteinase inhibitors soyacystatin N (scN) and E-64 against southern corn rootworm reared on artificial diet to determine the effects on larvae development and mortal...

  20. Larval development of the rock shrimp Rhynchocinetes typus Milne Edwards, 1937 (Decapoda, Caridea reared in the laboratory Desarrollo larval del camarón de roca Rhynchocinetes typus Milne Edwards, 1937 (Decapoda, Caridea cultivados en laboratorio

    Directory of Open Access Journals (Sweden)

    ENRIQUE DUPRÉ

    2008-06-01

    Full Text Available The first description of the larval stages of a representative of the family Rhynchocinetidae from the southeastern Pacific coast of South América is presented. Larvae of the rock shrimp Rhynchocinetes typus, from rocky subtidal environment of the Chile-Pera coast were reared in the laboratory at 22 °C, salinity 32 and feeding with Anemia franciscana. Seven zoeal stages, which occur through 10 successive moults, are described and illustrated in detail. Morphological comparison made between R. typus and other congeneric and related species belonging to Rhynchocinetid showed the main characteristic for the diagnosis of zoeal stages are: (a the pereiopods appear in the third stage, (b the exopod of the antennae have six segments, and (c no pleopods were found on the seven stages. The main difference with related species was the presence of three lacinia in the right mandible at stage VIL.Se describe por primera vez el desarrollo larval de un representante de la familia Rhynchocinetidae en aguas del Pacífico suroriental. Las larvas de camarón de roca Rhynchocinetes typus Milne Edwards, 1937 que habita en el submareal rocoso de la costa de Chile-Perú, se cultivaron en laboratorio a 22 °C, con salinidad de 32 y se alimentaron con Anemia franciscana. Se determinaron siete estados de zoea que ocurren a través de 10 mudas sucesivas. Cada uno de los estados se describió e ilustró detalladamente. La comparación morfológica con otras especies congenéricas y otras especies de la familia Rhynchocinetidae indicó que las principales características distintivas de los estados de zoea fueron: (a el primer par de pereiópodos aparece en la zoea III, (b el exopodito de la antena presenta seis segmentos, y (c no se observaron pleópodos en ninguno de los siete estados descritos. La principal característica que diferencia la zoea de R. typus de las demás especies es la presencia de tres lacinias en la mandíbula derecha en el estado VIL.

  1. Do larval traits re-evolve? Evidence from the embryogenesis of a direct-developing salamander, Plethodon cinereus.

    Science.gov (United States)

    Kerney, Ryan R; Blackburn, David C; Müller, Hendrik; Hanken, James

    2012-01-01

    Recent molecular phylogenies suggest the surprising reacquisition of posthatching metamorphosis within an otherwise direct-developing clade of lungless salamanders (family Plethodontidae). Metamorphosis was long regarded as plesiomorphic for plethodontids, yet the genus Desmognathus, which primarily includes metamorphosing species, is now nested within a much larger clade of direct-developing species. The extent to which the putative reacquisition of metamorphosis in Desmognathus represents a true evolutionary reversal is contingent upon the extent to which both larva-specific features and metamorphosis were actually lost during the evolution of direct development. In this study we analyze development of the hyobranchial skeleton, which is dramatically remodeled during salamander metamorphosis, in the direct-developing red-backed salamander, Plethodon cinereus. We find dramatic remodeling of the hyobranchial skeleton during embryogenesis in P. cinereus and the transient appearance of larva-specific cartilages. Hyobranchial development in this direct-developing plethodontid is highly similar to that in metamorphosing plethodontids (e.g., Desmognathus). The proposed reacquisition of hyobranchial metamorphosis within Desmognathus does not represent the "re-evolution" of a lost phenotype, but instead the elaboration of an existing developmental sequence. © 2011 The Author(s). Evolution © 2011 The Society for the Study of Evolution.

  2. The development of the larval nervous system, musculature and ciliary bands of Pomatoceros lamarckii (Annelida: heterochrony in polychaetes

    Directory of Open Access Journals (Sweden)

    Shimeld Sebastian M

    2006-10-01

    Full Text Available Abstract Background To understand the evolution of animals it is essential to have taxon sampling across a representative spread of the animal kingdom. With the recent rearrangement of most of the Bilateria into three major clades (Ecdysozoa, Lophotrochozoa and Deuterostomia it has become clear that the Lophotrochozoa are relatively poorly represented in our knowledge of animal development, compared to the Ecdysozoa and Deuterostomia. We aim to contribute towards redressing this balance with data on the development of the muscular, nervous and ciliary systems of the annelid Pomatoceros lamarckii (Serpulidae. We compare our data with other lophotrochozoans. Results P. lamarckii develops locomotory and feeding structures that enable it to become a swimming, planktotrophic larva within 24 hours. Formation of the trochophore includes development of a prototroch, metatroch and neurotroch, development of apical and posterior nervous elements at similar times, and development of musculature around the ciliary bands and digestive tract prior to development of any body wall muscles. The adult nervous and muscular systems are essentially preformed in the late larva. Interestingly, the muscular systems of the larvae and juvenile worms do not include the circular muscles of the body wall, which are considered to be plesiomorphic for annelids, although the possibility that circular muscles develop after these stages cannot be ruled out at this point. Conclusion A comparison between polychaetes shows variability in the timing (heterochrony of development of body wall muscles and elements of the nervous system. These heterochronies are one route for evolution of different life history strategies, such as adaptations to feeding requirements.

  3. Ramathibodi Language Development Questionnaire: A Newly Developed Screening Tool for Detection of Delayed Language Development in Children Aged 18-30 Months.

    Science.gov (United States)

    Chuthapisith, Jariya; Wantanakorn, Pornchanok; Roongpraiwan, Rawiwan

    2015-08-01

    To develop a parental questionnaire for screening children with delayed language development in primary care settings. Ramathibodi Language Development (RLD) questionnaire was developed and completed by groups of 40 typically developing children age 18 to 30 months old and 30 children with delayed language development. The mean score was significantly lower in the delay language group (6.7 ± 1.9), comparing with the typically developing group (9.6 ± 0.7). The optimal ROC curve cut-off score was 8 with corresponding sensitivity and specificity were 98% and 72%, respectively. The corresponding area under the curve was 0.96 (95% CI = 0.92-0.99). The RLD questionnaire was the promising language developmental screening instrument that easily utilized in well-child examination settings.

  4. 大菱鲆仔鱼皮肤发育及超微结构%Development and ultrastructure of larval skin in Scophthamus maximus

    Institute of Scientific and Technical Information of China (English)

    朱杰; 张秀梅; 高天翔; 姜明

    2003-01-01

    利用光镜和透射电镜技术对大菱鲆仔鱼皮肤的发育及超微结构进行了观察.大菱鲆早期仔鱼鱼体两侧皮肤结构完全对称.变态前仔鱼的皮肤发育缓慢,l~25d仔鱼的皮肤由l~2层表皮细胞和不发达的真皮层组成.变态开始后,皮肤的发育速度明显加快.至变态结束(60 d左右),仔鱼的皮肤由3~4层表皮细胞和发达的皮下胶原层组成.随着变态发育,大菱鲆仔鱼有眼侧皮肤与无眼侧皮肤结构上出现差异.超微结构观察显示大菱鲆的表皮包括3种表皮细胞:含微丝细胞,黏液细胞和氯细胞.有眼侧表皮细胞胞质内有大量空泡结构,表皮结构较疏松,仅有1种含微丝细胞.无眼侧表皮细胞胞质密度较高,表皮细胞排列紧密,具有两种结构和电子密度各异的含微丝细胞.在真皮层的疏松结缔组织层中有黑色素胞、虹彩色素胞,纤维芽细胞和其他类型的细胞及组织分布其中,黑色素胞中色素颗粒的密度及分布随仔鱼的发育及皮肤的着色状况而发生变化.这种伴随变态而产生的鱼体两侧皮肤结构的差异,是大菱鲆仔鱼由浮游生活转入底栖生活的一种生态学适应.%The histological development and ultrastructure of larval turbot skin were studied by both light and transmission electron microscopes. The early larvae showed a complete bisymmetry of skin. The skin of 1 - 25days old larvae developed slowly and was composed of the thin epidermis of 1 - 2 layers epidermal cells and undeveloped dermis before the metamorphosis. But the skin developed significantly when the metamorphosis began. Till the completion of metamorphosis ( about 60 days old), the skin contained 3 - 4 layers epidermal cells and very developed collagenous strata. With the process of metamorphosis, the ocular side skin and blind side skin became different in ultrastructure. Ultrastructural observation showed the epidermis of turbot contained three types of epidermal

  5. Shifty salamanders: transient trophic polymorphism and cannibalism within natural populations of larval ambystomatid salamanders

    OpenAIRE

    Jefferson, Dale M; Ferrari, Maud CO; Mathis, Alicia; Hobson, Keith A.; Eric R Britzke; Crane, Adam L; Blaustein, Andrew R.; Chivers, Douglas P.

    2014-01-01

    Introduction Many species of ambystomatid salamanders are dependent upon highly variable temporary wetlands for larval development. High larval densities may prompt the expression of a distinct head morphology that may facilitate cannibalism. However, few studies have characterized structural cannibalism within natural populations of larval salamanders. In this study we used two species of larval salamanders, long-toed (Ambystoma macrodactylum) and ringed salamanders (A. annulatum). Head morp...

  6. Larval development of Lepidophthalmus siriboia Felder & Rodrigues, 1993 (Decapoda: Thalassinidea from the Amazon region, reared in the laboratory O desenvolvimento larval de Lepidophthalmus siriboia Felder & Rodrigues, 1993 (Decapoda: Thalassinidea da região amazônica, cultivado em laboratório

    Directory of Open Access Journals (Sweden)

    Fernando A. Abrunhosa

    2005-01-01

    Full Text Available The complete larval development of the ghost shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993 was described and illustrated in detail from specimens reared in the laboratory. Ovigerous females were collected at Canela Island in the northeastern region of the State of Pará. The larvae hatch as a prezoea, in which they persist for less than 3 hours. The larval development consists of three zoeal stages and a megalopa. The zoeal development averaged from 69 to 111 hours. The period in the megalopa stage was about 185 hours (about 8 days. The percentage of individuals succeeding in molt into juvenile stage was 91,8%. The first juvenile stage was reached 254 hours (about 10 days after hatching. Morphological comparisons and their relationship with larvae of congeneric species are briefly discussed.O desenvolvimento completo de Lepidophthalmus siriboia Felder & Rodrigues, 1993 foi descrito e ilustrado em detalhes a partir de espécimens cultivados em laboratório. Fêmeas ovígeras foram coletadas na ilha de Canela nordeste do Estado do Pará. As larvas eclodem como prezoea e o desenvolvimento larval consiste de 3 estágios de zoea e 1 de megalopa. O desenvolvimento dos 3 estágios de zoea durou em média de 69 a 111 horas. A duração de megalopa foi cerca de 185 horas (cerca de 8 dias. O primeiro juvenil foi alcançado em 254 horas (cerca de 10 dias após a eclosão. Comparações morfológicas com espécies do mesmo gênero são discutidas.

  7. Embryonic and Early Larval Development of Schizothorax wangchiachii%短须裂腹鱼胚胎与仔鱼早期发育特性研究

    Institute of Scientific and Technical Information of China (English)

    左鹏翔; 尹翔; 胡思波; 李光华; 冷云; 张建斌; 缪祥军; 王志飞; 崔丽莉; 梁祥; 钟文武

    2015-01-01

    为积累短须裂腹鱼的基础生物学资料,并对规模化人工繁殖提供理论指导,利用养殖条件下的短须裂腹鱼亲鱼,通过干法授精获得受精卵,对其胚胎发育和仔鱼早期发育全过程进行连续观察。短须裂腹鱼受精卵的平均卵径为2.36 mm,吸水膨胀后为3.68 mm,沉性卵、弱粘性、卵黄丰富。在水温(14±1)℃的条件下,受精后6 h 30 min进入卵裂期,20 h 55 min进入囊胚期,60 h 28 min进入原肠期,70 h 4 min进入原肠中期,77 h 52 min进入神经胚期,142 h肌肉开始收缩,177 h 46 min进入心动期,254 h 40 min开始出膜。孵化全过程所需积温为3565.3℃· h。初孵仔鱼全长8.7 mm。出膜后第2~9天,胸鳍、鳃、口腔、眼色素、体内血管等器官相继发育完全;第10天仔鱼全长达15.15mm,鳔充气,鱼苗开始平游和觅食。孵化过程中应重点防控水霉病。早期仔鱼可以投喂轮虫、蛋黄或者豆浆等,待仔鱼捕食能力变强之后,可以投喂更加适口的枝角类、嫩口丰年虫等。%Schizothorax wangchiachii is one of the primary economic fish in the Jinsha River and its tributaries .The species is also ecologically important and one of the indigenous fish listed in the artificial breeding and release pro -gram for Longkaikou and Ahai hydropower stations on the middle Jinsha River .The potential for large-scale cultu-ring of S.wangchiachii is indicated by high market demand and declining wild populations .However, little is pres-ently known about embryonic and larval development of S.wangchiachii.In this study embryonic and early larval stage S.wangchiachii, maintained under controlled laboratory conditions , were described and illustrated .On March 9, 2014, parental stock was selected from the breeding and release station at Longkaikou hydropower station and a total of 67 860 zygotes were obtained by dry fertilization .The incubation of zygotes and the

  8. Morphological observation on larval and juvenile development of Oncorhynchus mykiss%斑点鳟仔、稚、幼鱼的形态发育

    Institute of Scientific and Technical Information of China (English)

    郭文; 高凤祥; 潘雷; 胡发文; 菅玉霞; 王雪; 张少春

    2012-01-01

    以斑点鳟(Oncorhynchus mykiss)发眼卵为材料,进行了发眼卵的人工孵化及仔鱼的人工培育研究.对斑点鳟仔稚鱼的形态发育进行了系统观察,描述了各发育期的形态特征,并测定生长参数.斑点鳟早期生活史的分期如下:初孵仔鱼全长14.25±0.45 mm,体重85±5 mg,肛门未开口,营内源性营养,脊柱末端向上弯曲;10 dph开始上浮,投喂卤虫;12 dph开口摄食,开始营内外源混合性营养;14 dph鳍膜消失,各鳍独立;16dph开始投喂配合饵料;24 dph卵黄囊吸收完毕,营完全外源性营养;34 dph,体侧形成8~9个幼鲑斑;44dph各鳍的鳍条发育健全;60 dph幼鱼外形为纺锤形,与成鱼相同.研究表明,斑点鳟早期生长发育过程中全长、肛门前长、水平眼径和头高的生长情况基本相同,0~ 16 dph生长速度较快,16~44dph生长速度较慢,44 dph后生长速度再次变快.%The paper reported the results of morphological observation on larval development of Oncorhynchus mykiss. The eyed eggs obtained from America were used in this study. Morphological development of fish larvae was systematically observed. The paper described the morphological characteristics of various developmental stages and measured growth parameters. The early life history of Oncorhynchus mykiss was: the total length of newly hatched larvae was 14.25 ±0.45 mm, the weight was 85 ±5 mg; the anus was not open, the larvae relied on their yolk for nourishment, the end of spine was upwarped; the larvae started floating at 10 dph, fed with artemia; the larval mouth opened at 12 dph; the fin membrance disappeared at 14 dph; the yolk was exhausted at 24 dph; 8 - 9 large black spots on the lateral formed at 34 dph; All fin rays and scales formed at 44 dph; the juvenile showed the appearence of small adults at 60 dph. The morphological development and changes of pigment pattern were observed. The development of head, dorsal spine, anal fin and caudal peduncle

  9. House and Stable Fly Seasonal Abundance, Larval Development Substrates, and Natural Parasitism on Small Equine Farms in Florida.

    Science.gov (United States)

    Machtinger, E T; Leppla, N C; Hogsette, J A

    2016-08-01

    House flies, Musca domestica Linnaeus, and stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are common pests on horse farms. The successful use of pupal parasitoids for management of these pests requires knowledge of seasonal fluctuations and biology of the flies as well as natural parasitism levels. However, these dynamics have not been investigated on small equine farms. A 1-year field study began in July 2010, in north central Florida, to determine adult fly population levels and breeding areas on four small equine farms. Weekly surveillance showed that pest flies were present year-round, though there were differences in adult population levels among farms and seasons. Fly development was not confirmed on two of the four small farms, suggesting that subtle differences in husbandry may adversely affect the development of immature flies. In six substrates previously identified as the most common among the farms, stable fly puparia were found overwhelmingly in hay mixed with equine manure and house fly puparia were found in fresh pine shavings mixed with equine manure. Natural parasitism was minimal as expected, but greatest numbers of natural parasitoids collected were of the genus Spalangia. Differences in adult and immature fly numbers recovered emphasizes the need for farm owners to confirm on-site fly development prior to purchase and release of biological control agents. Additionally, due to the low natural parasitism levels and domination of parasitism by Spalangia cameroni, augmentative releases using this species may be the most effective.

  10. Mouse zygotes respond to severe sperm DNA damage by delaying paternal DNA replication and embryonic development.

    Directory of Open Access Journals (Sweden)

    Joanna E Gawecka

    Full Text Available Mouse zygotes do not activate apoptosis in response to DNA damage. We previously reported a unique form of inducible sperm DNA damage termed sperm chromatin fragmentation (SCF. SCF mirrors some aspects of somatic cell apoptosis in that the DNA degradation is mediated by reversible double strand breaks caused by topoisomerase 2B (TOP2B followed by irreversible DNA degradation by a nuclease(s. Here, we created zygotes using spermatozoa induced to undergo SCF (SCF zygotes and tested how they responded to moderate and severe paternal DNA damage during the first cell cycle. We found that the TUNEL assay was not sensitive enough to identify the breaks caused by SCF in zygotes in either case. However, paternal pronuclei in both groups stained positively for γH2AX, a marker for DNA damage, at 5 hrs after fertilization, just before DNA synthesis, while the maternal pronuclei were negative. We also found that both pronuclei in SCF zygotes with moderate DNA damage replicated normally, but paternal pronuclei in the SCF zygotes with severe DNA damage delayed the initiation of DNA replication by up to 12 hrs even though the maternal pronuclei had no discernable delay. Chromosomal analysis of both groups confirmed that the paternal DNA was degraded after S-phase while the maternal pronuclei formed normal chromosomes. The DNA replication delay caused a marked retardation in progression to the 2-cell stage, and a large portion of the embryos arrested at the G2/M border, suggesting that this is an important checkpoint in zygotic development. Those embryos that progressed through the G2/M border died at later stages and none developed to the blastocyst stage. Our data demonstrate that the zygote responds to sperm DNA damage through a non-apoptotic mechanism that acts by slowing paternal DNA replication and ultimately leads to arrest in embryonic development.

  11. Effects of exposure to 17α-ethynylestradiol during larval development on growth, sexual differentiation, and abundances of transcripts in the liver of the wood frog (Lithobates sylvaticus).

    Science.gov (United States)

    Tompsett, Amber R; Wiseman, Steve; Higley, Eric; Giesy, John P; Hecker, Markus

    2013-01-15

    Populations of amphibians are in decline in certain locations around the world, and the possible contribution of environmental contaminants, including estrogenic compounds, to these declines is of potential concern. In the current study, responses of the wood frog (Lithobates sylvaticus) to exposure to 17α-ethynylestradiol (EE2), the synthetic estrogen used in oral contraceptives, during the larval period were characterized. Exposure of L. sylvaticus to 1.08, 9.55, or 80.9 μg EE2/L had no effects on survival, growth, or metamorphic endpoints monitored in the current study. However, there were significant effects of exposure to EE2 on phenotypic sex ratios. In general, lesser proportions of L. sylvaticus developed as phenotypic males and greater proportions developed as phenotypic females or with mixed sex phenotypes at all concentrations of EE2 tested. Utilizing the data collected in the current study, the EC(50) for complete feminization of L. sylvaticus was determined to be 7.7 μg EE2/L, and the EC(50) for partial feminization was determined to be 2.3 μg EE2/L. In addition, after chronic exposure, abundances of transcripts of vitellogenin A2, high density lipoprotein binding protein, and 7-dehydrocholesterol reductase were 1.8-280-fold greater in livers from L. sylvaticus exposed to EE2 compared to controls. Overall, there were significant effects of exposure to all concentrations of EE2 tested, the least of which was within about 2-fold of estrogen equivalent concentrations previously measured in the environment. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Effects of exposure to 17{alpha}-ethynylestradiol during larval development on growth, sexual differentiation, and abundances of transcripts in the liver of the wood frog (Lithobates sylvaticus)

    Energy Technology Data Exchange (ETDEWEB)

    Tompsett, Amber R., E-mail: amber.tompsett@usask.ca [Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); Wiseman, Steve; Higley, Eric [Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); Giesy, John P. [Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); Dept. of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK (Canada); Dept. of Biology and Chemistry and State Key Laboratory for Marine Pollution, City University of Hong Kong, Hong Kong, Special Administrative Region (Hong Kong); Hecker, Markus [Toxicology Centre, University of Saskatchewan, Saskatoon, SK (Canada); School of the Environment and Sustainability, University of Saskatchewan, Saskatoon, SK (Canada)

    2013-01-15

    Populations of amphibians are in decline in certain locations around the world, and the possible contribution of environmental contaminants, including estrogenic compounds, to these declines is of potential concern. In the current study, responses of the wood frog (Lithobates sylvaticus) to exposure to 17{alpha}-ethynylestradiol (EE2), the synthetic estrogen used in oral contraceptives, during the larval period were characterized. Exposure of L. sylvaticus to 1.08, 9.55, or 80.9 {mu}g EE2/L had no effects on survival, growth, or metamorphic endpoints monitored in the current study. However, there were significant effects of exposure to EE2 on phenotypic sex ratios. In general, lesser proportions of L. sylvaticus developed as phenotypic males and greater proportions developed as phenotypic females or with mixed sex phenotypes at all concentrations of EE2 tested. Utilizing the data collected in the current study, the EC{sub 50} for complete feminization of L. sylvaticus was determined to be 7.7 {mu}g EE2/L, and the EC{sub 50} for partial feminization was determined to be 2.3 {mu}g EE2/L. In addition, after chronic exposure, abundances of transcripts of vitellogenin A2, high density lipoprotein binding protein, and 7-dehydrocholesterol reductase were 1.8-280-fold greater in livers from L. sylvaticus exposed to EE2 compared to controls. Overall, there were significant effects of exposure to all concentrations of EE2 tested, the least of which was within about 2-fold of estrogen equivalent concentrations previously measured in the environment.

  13. Ultramorphology of digestive tract of Anticarsia gemmatalis (Hübner, 1818 (Lepidoptera: Noctuidae at final larval development/ Ultramorfologia do trato digestivo de Anticarsia gemmatalis (Hübner, 1818 (Lepidoptera: Noctuidae no final do desenvolvimento larval

    Directory of Open Access Journals (Sweden)

    Luis Antônio Toledo

    2008-08-01

    Full Text Available The digestive tract of insects is an important natural, physical, and chemical defense barrier against pathogen invasion. Certain lepidopteran caterpillars are serious pests of agricultural crops and their biology has received much attention, but little is known about the larval noctuid gut. The morphological analysis of the digestive tract in Anticarsia gemmatalis under scanning electron microscopy (SEM is a good model for studies about its defense mechanism. The material was fixed (2,5% glutaraldehyde solution; 0.1M-phosphate buffer, pH 7.3, post-fixed (1% osmium tetroxide in the same buffer, dried at critical point, gold coated and analyzed in a SEM 515-Philips. A. gemmatalis digestive tract consists of a straight duct of varying length and diameter, subdivided in three main regions: the foregut formed by the oral cavity, pharynx, esophagus, and crop; the midgut that is the largest portion of the digestive tract without noticeable morphological differentiation along its length; and the hindgut that is morphologically differentiated in pylorus, ileum, colon, and rectum. Although the general morphology of the A. gemmatalis digestive tract is quite similar to the other Lepidoptera species, the anatomical array of the crop muscular layers is quite different comparing with the description for other larval insect.O trato digestivo dos insetos constitui uma importante barreira físico-química natural contra invasão de patógenos. Algumas larvas de lepidópteros são consideradas pragas agrícolas potenciais e sua biologia tem recebido muita atenção; no entanto, pouco se sabe sobre a morfologia do sistema digestivo. A análise morfológica do trato digestivo de Anticarsia gemmatalis em nível ultraestrutural é um método bastante eficaz para o estudo dos seus mecanismos de defesa. Os materiais foram fixados (solução de glutaraldeído 2,5%; 0.1M tampão fosfato, pH 7.3, pós-fixados (tetróxido de ósmio 1% no mesmo tampão, desidratados em

  14. Larval development of Spodoptera eridania (Cramer fed on leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins and its non-Bt isoline

    Directory of Open Access Journals (Sweden)

    Orcial Ceolin Bortolotto

    2015-03-01

    Full Text Available This study aimed to evaluate, in controlled laboratory conditions (temperature of 25±2 °C, relative humidity of 60±10%, and 14/10 h L/D photoperiod, the larval development of Spodoptera eridania (Cramer, 1784 (Lepidoptera, Noctuidae fed with leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 insecticide proteins and its non-Bt isoline. Maize leaves triggered 100% of mortality on S. eridania larvae independently of being Bt or non-Bt plants. However, it was observed that in overall Bt maize (expressing a single or pyramided protein slightly affects the larval development of S. eridania, even under reduced leaf consumption. Therefore, these results showed that Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 can affect the larval development of S. eridania, although it is not a target pest of this plant; however, more research is needed to better understand this evidence. Finally, this study confirms that non-Bt maize leaves are unsuitable food source to S. eridania larvae, suggesting that they are not a potential pest in maize fields.

  15. Larval nervous systems

    DEFF Research Database (Denmark)

    Nielsen, Claus

    2015-01-01

    The apical organ of ciliated larvae of cnidarians and bilaterians is a true larval organ that disappears before or at metamorphosis. It appears to be sensory, probably involved in metamorphosis, but knowledge is scant. The ciliated protostome larvae show ganglia/nerve cords that are retained as t...... common ancestor of the deuterostomes was very similar to the latest common pelago-benthic ancestor of the protostomes as described by the trochaea theory, and that the neural tube of the chordates is morphologically ventral....

  16. Immature development of the malaria vector mosquito, Anopheles gambiae S.L. (Diptera: Culicidae), in relation to soil-substrate organic matter content of larval habitats in northcentral Nigeria.

    Science.gov (United States)

    Olayemi, I K; Ojo, V O

    2013-02-01

    This study elucidated the relationships between larval habitat soil-substrate Organic Matter Content (OMC) and immature development of the mosquito Anopheles gambiae S.L. Day-old larvae of the mosquito were reared in media substrated with typical soil samples (i.e., sandy, silt, clayey and loamy soils), from established anopheline breeding sites, to provide a gradient in soil-substrate OMC. The OMC of the soil samples were determined by ignition to a constant weight; while the developing A. gambiae mosquitoes in the culture media were monitored daily for survivorship and duration of immature life stages. The results indicated significant (p OMC of the soil types (range = 11.21 +/- 2.91% in sandy to 29.83 +/- 2.96% in loamy soils). However, though Daily Larval Survival Rates (DLSR) were relatively high (range = 95.21 +/- 2.96 to 96.70 +/- 1.44%), as influenced by OMC, such values were not significantly different (p > 0.05) among the soil-substrate types; results contrary to those of Larval Success Rates (LSR) (i.e., range = 52.07 +/- 13.64 to 74.39 +/- 6.60%). Daily Pupation Rate (DPR) of the mosquitoes varied significantly among the soil-substrates, ranging from 13.87 +/- 2.39% in clayey to 25.00 +/- 4.30% in loamy substrates. Soil-substrate OMC significantly extended the Duration of Immature Life Stages (DILS) of the mosquitoes only in the sandy soil type (range = 12.76 +/- 1.74 to 15.81 +/- 2.40 days). On the whole, DILS was inversely related to soil-substrate OMC. Cross-correlational analysis revealed significant positive association among most of the variables tested. The findings of this study should serve as baseline information for the development of effective environmental management strategies for malaria larval-vector control.

  17. Utilization of blueberry by the lappet moth, Streblote panda Hübner (Lepidoptera: Lasiocampidae): survival, development, and larval performance.

    Science.gov (United States)

    Calvo, D; Molina, J Ma

    2004-06-01

    The lappet moth, Streblote panda Hübner [1820] (Lasiocampidae), is a common species found in blueberry, Vaccinium spp. (Ericaceae) fields of Western Andalusia. The biology of this species as well as the extent to which its larvae can use and survive on blueberry is unknown. In this study, the suitability to larvae of several blueberry cultivars was studied. Larvae were grown under controlled laboratory conditions on excised foliage of six blueberry cultivars. Survival, development, and food use were determined for first and fifth instars. According to our results, blueberry has become an alternative host plant for S. panda in southwestern Andalusia. Low growth rates and efficiencies of use of food were observed. Lower gross efficiency of growth was found for larvae fed blueberry 'Sharpblue', despite a higher apparent digestibility of this cultivar. Larvae reared on this cultivar had the highest mortality, increased developmental time, and used a greater part of metabolism for maintenance. Herbivore pressure may be increased with the widespread planting of the most suitable cultivars 'Misty' and 'O'Neal', whereas 'Sharpblue' and'Climax' seem to be the least suitable host plants. These data provide useful information for planning and managing blueberry orchards in the presence of S. panda populations.

  18. Effect of three larval diets on the development of the armyworm, Spodoptera latifascia Walker, 1856 (Noctuidae, Lepidoptera

    Directory of Open Access Journals (Sweden)

    M. E. M. Habib

    1982-01-01

    Full Text Available Some biological effects of feeding larvae of the armyworm Spodoptera latifascia with leaves of three plant species (cotton, soybean and lettuce have been studied. Some indicative measurements were utilized to determine the host suitability of these three plant species. Cotton leaves (Gossypium hirsutum were found to be better than soybean (Glycine max for the development and growth of this insect. Lettuce leaves (Lactuca sativa were incapable of sustaining this insect. Moreover, the stress of the latter diet was associated with a latent microbial disease, a mixed infection caused by Vairimorpha sp. and a nuclear polyhedrosis virus (NPV. Cotton leaves can be recommended as a suitable diet for mass rearing of this insect species. Due to recent outbreks of S. latifascia observed in the States of São Paulo, Santa Catarina and Paraná and because of the frequent applications of wide spectrum chemical insecticides, it can be expected that this insect will soon become one of the important pests threatening cotton and other economic plantations in Brazil.

  19. Mixed effects of elevated pCO2 on fertilisation, larval and juvenile development and adult responses in the mobile subtidal scallop Mimachlamys asperrima (Lamarck, 1819.

    Directory of Open Access Journals (Sweden)

    Elliot Scanes

    Full Text Available Ocean acidification is predicted to have severe consequences for calcifying marine organisms especially molluscs. Recent studies, however, have found that molluscs in marine environments with naturally elevated or fluctuating CO2 or with an active, high metabolic rate lifestyle may have a capacity to acclimate and be resilient to exposures of elevated environmental pCO2. The aim of this study was to determine the effects of near future concentrations of elevated pCO2 on the larval and adult stages of the mobile doughboy scallop, Mimachlamys asperrima from a subtidal and stable physio-chemical environment. It was found that fertilisation and the shell length of early larval stages of M. asperrima decreased as pCO2 increased, however, there were less pronounced effects of elevated pCO2 on the shell length of later larval stages, with high pCO2 enhancing growth in some instances. Byssal attachment and condition index of adult M. asperrima decreased with elevated pCO2, while in contrast there was no effect on standard metabolic rate or pHe. The responses of larval and adult M. asperrima to elevated pCO2 measured in this study were more moderate than responses previously reported for intertidal oysters and mussels. Even this more moderate set of responses are still likely to reduce the abundance of M. asperrima and potentially other scallop species in the world's oceans at predicted future pCO2 levels.

  20. Life in acid: interactive effects of pH and natural organic acids on growth, development and locomotor performance of larval striped marsh frogs (Limnodynastes peronii).

    Science.gov (United States)

    Barth, B J; Wilson, R S

    2010-04-01

    The low pH of naturally acidic aquatic environments is the result of soft-water with low buffering capacity and high concentrations of natural organic acids. Our current understanding of the influence of pH on aquatic organisms is largely limited to laboratory studies conducted under controlled conditions with little incorporation of these organic acids. Recent studies suggest natural organic acids may influence the physiology of aquatic species independent of low pH. We examined the effects of pH and varying concentrations of natural wallum water, which is high in organic acids on the hatching success, growth and locomotor performance of larval striped marsh frogs (Limnodynastes peronii). Based on previous studies, we predicted that the detrimental effects of low pH would be further exacerbated by higher concentrations of naturally occurring organic acids (high concentrations of wallum water). In artificial soft-water, embryos experienced both reduced growth and reduced survival when exposed to low pH. However, greater concentrations of natural organic acids did not exacerbate these effects of low pH on growth and development. Instead, we found some evidence that the natural organic acids within wallum water improved growth and swimming performance across all pH treatments. Using path analyses to investigate the effects of pH and natural organic acid concentration on burst swimming performance, we found performance was directly affected by both body length and organic acid concentration. Our data further highlight our limited understanding of the importance of natural organic acids for aquatic organisms and the need to incorporate greater ecological relevance into these studies.

  1. THE RESPONSE TO SELECTION FOR FAST LARVAL DEVELOPMENT IN DROSOPHILA MELANOGASTER AND ITS EFFECT ON ADULT WEIGHT: AN EXAMPLE OF A FITNESS TRADE-OFF.

    Science.gov (United States)

    Nunney, Leonard

    1996-06-01

    A selection experiment using Drosophila melanogaster revealed a strong trade-off between adult weight and larval development time (LDT), supporting the view that antagonistic pleiotropy for these two fitness traits determines mean adult size. Two experimental lines of flies were selected for a shorter LDT (measured from egg laying to pupation). After 15 generations LDT was reduced by an average of 7.9%. The response appeared to be controlled primarily by autosomal loci. A correlated response to the selection was a reduction in adult dry weight: individuals from the selected populations were on average 15.1% lighter than the controls. The lighter females of the selected lines showed a 35% drop in fecundity, but no change in longevity. Thus, there is no direct relationship between LDT and adult longevity. The genetic correlation between weight and LDT, as measured from their joint response to selection, was 0.86. Although there was weak evidence for dominance in LDT, there was none for weight, making it unlikely that selection acting on this antagonistic pleiotropy could lead to a stable polymorphism. In all lines, sex differences in weight violated expectations based on intrasex genetic correlations: Females, being larger than males, ought to require a longer LDT, whereas there was a slight trend in the opposite direction. Because the sexual dimorphism in size was not significantly altered by selection, it appears that the controlling loci are either invariant or have very limited pleiotropic effect on developmental time. It is suggested that they probably control some intrinsic, energy-intensive developmental process in males. © 1996 The Society for the Study of Evolution.

  2. Drought stress delays endosperm development and misregulates genes associated with cytoskeleton organization and grain quality proteins in developing wheat seeds.

    Science.gov (United States)

    Begcy, Kevin; Walia, Harkamal

    2015-11-01

    Drought stress is a major yield-limiting factor for wheat. Wheat yields are particularly sensitive to drought stress during reproductive development. Early seed development stage is an important determinant of seed size, one of the yield components. We specifically examined the impact of drought stress imposed during postzygotic early seed development in wheat. We imposed a short-term drought stress on plants with day-old seeds and observed that even a short-duration drought stress significantly reduced the size of developing seeds as well as mature seeds. Drought stress delayed the developmental transition from syncytial to cellularized stage of endosperm. Coincident with reduced seed size and delayed endosperm development, a subset of genes associated with cytoskeleton organization was misregulated in developing seeds under drought-stressed. Several genes linked to hormone pathways were also differentially regulated in response to drought stress in early seeds. Notably, drought stress strongly repressed the expression of wheat storage protein genes such as gliadins, glutenins and avenins as early as 3 days after pollination. Our results provide new insights on how some of the early seed developmental events are impacted by water stress, and the underlying molecular pathways that can possibly impact both grain size and quality in wheat.

  3. Insulin- and Warts-Dependent Regulation of Tracheal Plasticity Modulates Systemic Larval Growth during Hypoxia in Drosophila melanogaster

    Science.gov (United States)

    Wong, Daniel M.; Shen, Zhouyang; Owyang, Kristin E.; Martinez-Agosto, Julian A.

    2014-01-01

    Adaptation to dynamic environmental cues during organismal development requires coordination of tissue growth with available resources. More specifically, the effects of oxygen availability on body size have been well-documented, but the mechanisms through which hypoxia restricts systemic growth have not been fully elucidated. Here, we characterize the larval growth and metabolic defects in Drosophila that result from hypoxia. Hypoxic conditions reduced fat body opacity and increased lipid droplet accumulation in this tissue, without eliciting lipid aggregation in hepatocyte-like cells called oenocytes. Additionally, hypoxia increased the retention of Dilp2 in the insulin-producing cells of the larval brain, associated with a reduction of insulin signaling in peripheral tissues. Overexpression of the wildtype form of the insulin receptor ubiquitously and in the larval trachea rendered larvae resistant to hypoxia-induced growth restriction. Furthermore, Warts downregulation in the trachea was similar to increased insulin receptor signaling during oxygen deprivation, which both rescued hypoxia-induced growth restriction, inhibition of tracheal molting, and developmental delay. Insulin signaling and loss of Warts function increased tracheal growth and augmented tracheal plasticity under hypoxic conditions, enhancing oxygen delivery during periods of oxygen deprivation. Our findings demonstrate a mechanism that coordinates oxygen availability with systemic growth in which hypoxia-induced reduction of insulin receptor signaling decreases plasticity of the larval trachea that is required for the maintenance of systemic growth during times of limiting oxygen availability. PMID:25541690

  4. Insulin- and warts-dependent regulation of tracheal plasticity modulates systemic larval growth during hypoxia in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Daniel M Wong

    Full Text Available Adaptation to dynamic environmental cues during organismal development requires coordination of tissue growth with available resources. More specifically, the effects of oxygen availability on body size have been well-documented, but the mechanisms through which hypoxia restricts systemic growth have not been fully elucidated. Here, we characterize the larval growth and metabolic defects in Drosophila that result from hypoxia. Hypoxic conditions reduced fat body opacity and increased lipid droplet accumulation in this tissue, without eliciting lipid aggregation in hepatocyte-like cells called oenocytes. Additionally, hypoxia increased the retention of Dilp2 in the insulin-producing cells of the larval brain, associated with a reduction of insulin signaling in peripheral tissues. Overexpression of the wildtype form of the insulin receptor ubiquitously and in the larval trachea rendered larvae resistant to hypoxia-induced growth restriction. Furthermore, Warts downregulation in the trachea was similar to increased insulin receptor signaling during oxygen deprivation, which both rescued hypoxia-induced growth restriction, inhibition of tracheal molting, and developmental delay. Insulin signaling and loss of Warts function increased tracheal growth and augmented tracheal plasticity under hypoxic conditions, enhancing oxygen delivery during periods of oxygen deprivation. Our findings demonstrate a mechanism that coordinates oxygen availability with systemic growth in which hypoxia-induced reduction of insulin receptor signaling decreases plasticity of the larval trachea that is required for the maintenance of systemic growth during times of limiting oxygen availability.

  5. Interactions between the inositol 1,4,5-trisphosphate and cyclic AMP signaling pathways regulate larval molting in Drosophila.

    Science.gov (United States)

    Venkatesh, K; Siddhartha, G; Joshi, R; Patel, S; Hasan, G

    2001-05-01

    Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the steroid hormone ecdysone, in response to neural signals, at precise stages during development. In this study we have analyzed, using genetic and molecular methods, the roles played by two major signaling pathways in the regulation of larval molting in Drosophila. Previous studies have shown that mutants for the inositol 1,4,5-trisphosphate receptor gene (itpr) are larval lethals. In addition they exhibit delays in molting that can be rescued by exogenous feeding of 20-hydroxyecdysone. Here we show that mutants for adenylate cyclase (rut) synergize, during larval molting, with itpr mutant alleles, indicating that both cAMP and InsP(3) signaling pathways function in this process. The two pathways act in parallel to affect molting, as judged by phenotypes obtained through expression of dominant negative and dominant active forms of protein kinase A (PKA) in tissues that normally express the InsP(3) receptor. Furthermore, our studies predict the existence of feedback inhibition through protein kinase A on the InsP(3) receptor by increased levels of 20-hydroxyecdysone.

  6. Prenatal MDMA exposure delays postnatal development in the rat: a preliminary study.

    Science.gov (United States)

    Heuland, Emilie; Germaux, Marie-Aure; Galineau, Laurent; Chalon, Sylvie; Belzung, Catherine

    2010-01-01

    3,4-methylenedioxymethamphetamine or MDMA (ecstasy) is a synthetic illicit drug which is widely consumed throughout the world. Drug abuse during pregnancy may have an impairing effect on the progeny of drug-abusing mothers. The purpose of the present study was to assess the effect of prenatal MDMA exposure on the progeny development, using a rat model. Pregnant animals were injected daily with MDMA (10 mg/kg) between the 13th and 20th days of gestation. Male and female pups were then tested throughout the lactation period on the appearance and improvement of physical and sensory motor parameters. Appearance of some physical features (eyes opening and incisor eruption) and neurological reflexes as well as improving performances in negative geotaxis, gait and inclined board tests were delayed in pups prenatally exposed to MDMA compared to saline-treated pups. In contrast, functions that are necessary for survival such as forelimb reflex (that enables suckling) were present in both groups. At four weeks of age, MDMA animals recovered to normal level in all studied parameters. The delay in physical and neurological reflex development could be interpreted as alterations in maturation of some neuronal circuitries induced by prenatal MDMA exposure.

  7. Seasonal life history trade-offs in two leafwing butterflies: Delaying reproductive development increases life expectancy.

    Science.gov (United States)

    McElderry, Robert M

    2016-04-01

    Surviving inhospitable periods or seasons may greatly affect fitness. Evidence of this exists in the prevalence of dormant stages in the life cycles of most insects. Here I focused on butterflies with distinct seasonal morphological types (not a genetic polymorphism) in which one morphological type, or form, delays reproduction until favorable conditions return, while the other form develops in an environment that favors direct reproduction. For two butterflies, Anaea aidea and A. andria, I tested the hypothesis that the development of each seasonal form involves a differential allocation of resources to survival at eclosion. I assayed differences in adult longevity among summer and winter forms in either a warm, active environment or a cool, calm environment. Winter form adults lived 40 times longer than summer form but only in calm, cool conditions. The magnitude of this difference provided compelling evidence that the winter form body plan and metabolic strategy (i.e. resource conservatism) favor long term survival. This research suggests that winter form adults maintain lowered metabolic rate, a common feature of diapause, to conserve resources and delay senescence while overwintering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Development and evaluation of a set of group delay standards. [deep space tracking station calibration

    Science.gov (United States)

    Otoshi, T. Y.; Beatty, R. W.

    1976-01-01

    A set of cable assemblies serving as group delay standards having nominal delays of 15, 30, and 60 nsec are described. Various types of measurements were performed on the cable standards, including impedance, microwave phase shift, RF pulse burst delay, modulation pulsed delay, and envelope phase shift measurements. The results of these tests are given, and various sources of error are discussed, in particular, dispersion and internal reflections.

  9. A preliminary study on the relationship between characteristics of TV content and delayed speech development in young children.

    Science.gov (United States)

    Okuma, Kanako; Tanimura, Masako

    2009-06-01

    Our previous population survey of 18-month-old children suggested an association between delayed language development and heavy TV viewing. We therefore collected all 85 videos described as children's favorites in that questionnaire to examine relationships between the characteristics of habitually viewed videos and language development. In the language delayed group, compared to the non-delayed group, the types of videos preferred more were "realistic animations" and "baby education" and the characteristics of videos were contained few close-ups of characters facing viewers, continued uninterruptedly between stories, had constant movement or transformation of characters, had a high frame rate of animation, and that adults readily kept on watching the videos even with the sound off. These characteristics were seen more in videos the above two types. These findings imply that habitual television/video viewing with characteristics that are not apt to elicit parent-child communication for long hours may affect delayed language development in young children.

  10. First feeding of larval herring

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Munk, Peter; Støttrup, Josianne

    1985-01-01

    The transition period from endogenous to exogenous feeding by larval herring was investigated in the laboratory for four herring stocks in order to evaluate the chances of survival at the time of fiest feeding. Observations on larval activity, feeding and growth were related to amount of yolk, vi...

  11. Alpha-1 antitrypsin protein and gene therapies decrease autoimmunity and delay arthritis development in mouse model

    Directory of Open Access Journals (Sweden)

    Atkinson Mark A

    2011-02-01

    Full Text Available Abstract Background Alpha-1 antitrypsin (AAT is a multi-functional protein that has anti-inflammatory and tissue protective properties. We previously reported that human AAT (hAAT gene therapy prevented autoimmune diabetes in non-obese diabetic (NOD mice and suppressed arthritis development in combination with doxycycline in mice. In the present study we investigated the feasibility of hAAT monotherapy for the treatment of chronic arthritis in collagen-induced arthritis (CIA, a mouse model of rheumatoid arthritis (RA. Methods DBA/1 mice were immunized with bovine type II collagen (bCII to induce arthritis. These mice were pretreated either with hAAT protein or with recombinant adeno-associated virus vector expressing hAAT (rAAV-hAAT. Control groups received saline injections. Arthritis development was evaluated by prevalence of arthritis and arthritic index. Serum levels of B-cell activating factor of the TNF-α family (BAFF, antibodies against both bovine (bCII and mouse collagen II (mCII were tested by ELISA. Results Human AAT protein therapy as well as recombinant adeno-associated virus (rAAV8-mediated hAAT gene therapy significantly delayed onset and ameliorated disease development of arthritis in CIA mouse model. Importantly, hAAT therapies significantly reduced serum levels of BAFF and autoantibodies against bCII and mCII, suggesting that the effects are mediated via B-cells, at least partially. Conclusion These results present a new drug for arthritis therapy. Human AAT protein and gene therapies are able to ameliorate and delay arthritis development and reduce autoimmunity, indicating promising potential of these therapies as a new treatment strategy for RA.

  12. Optimized energy-delay sub-network routing protocol development and implementation for wireless sensor networks

    Science.gov (United States)

    Fonda, James W.; Zawodniok, Maciej; Jagannathan, S.; Watkins, Steve E.

    2008-08-01

    The development and the implementation issues of a reactive optimized energy-delay sub-network routing (OEDSR) protocol for wireless sensor networks (WSN) are introduced and its performance is contrasted with the popular ad hoc on-demand distance vector (AODV) routing protocol. Analytical results illustrate the performance of the proposed OEDSR protocol, while experimental results utilizing a hardware testbed under various scenarios demonstrate improvements in energy efficiency of the OEDSR protocol. A hardware platform constructed at the University of Missouri-Rolla (UMR), now the Missouri University of Science and Technology (MST), based on the Generation 4 Smart Sensor Node (G4-SSN) prototyping platform is also described. Performance improvements are shown in terms of end-to-end (E2E) delay, throughput, route-set-up time and drop rates and energy usage is given for three topologies, including a mobile topology. Additionally, results from the hardware testbed provide valuable lessons for network deployments. Under testing OEDSR provides a factor of ten improvement in the energy used in the routing session and extends network lifetime compared to AODV. Depletion experiments show that the time until the first node failure is extended by a factor of three with the network depleting and network lifetime is extended by 6.7%.

  13. Developing an Inspection Optimization Model Based on the Delay-Time Concept

    Directory of Open Access Journals (Sweden)

    Ehsan Nazemi

    2015-01-01

    Full Text Available Infrastructures are considered as important facilities required for every country and society to be able to work properly. Aging and deterioration of such structures during their lifetime are a major concern both for maintenance researchers in the academic world and for the practitioners. This concern is mainly because the deterioration increases the maintenance costs dramatically and lowers the reliability, availability, and safety of the structural system. Preventive maintenance and inspection activities are the most usual means for keeping the structure in a good condition. This paper utilizes the concept of delay-time for developing the optimal inspection policy for deteriorating structures. In the proposed stochastic model, discrete times of inspection activities are taken as the decision variables of an optimization problem, in a way that the obtained aperiodic (nonuniform inspection schedule minimizes the total downtime ratio of the structure. To illustrate the model capabilities, various numerical examples are solved and results are compared with the traditional periodic (uniform inspection policies. The results indicate the substantial reduction in system downtime due to the wisely planned inspection schedule and the appropriate utilization of delay-time concept, which is indeed a powerful framework for inspection optimization problems.

  14. Drosophila adult and larval pheromones modulate larval food choice.

    Science.gov (United States)

    Farine, Jean-Pierre; Cortot, Jérôme; Ferveur, Jean-François

    2014-06-07

    Insects use chemosensory cues to feed and mate. In Drosophila, the effect of pheromones has been extensively investigated in adults, but rarely in larvae. The colonization of natural food sources by Drosophila buzzatii and Drosophila simulans species may depend on species-specific chemical cues left in the food by larvae and adults. We identified such chemicals in both species and measured their influence on larval food preference and puparation behaviour. We also tested compounds that varied between these species: (i) two larval volatile compounds: hydroxy-3-butanone-2 and phenol (predominant in D. simulans and D. buzzatii, respectively), and (ii) adult cuticular hydrocarbons (CHs). Drosophila buzzatii larvae were rapidly attracted to non-CH adult conspecific cues, whereas D. simulans larvae were strongly repulsed by CHs of the two species and also by phenol. Larval cues from both species generally reduced larval attraction and pupariation on food, which was generally--but not always--low, and rarely reflected larval response. As these larval and adult pheromones specifically influence larval food search and the choice of a pupariation site, they may greatly affect the dispersion and survival of Drosophila species in nature.

  15. [Delayed development of hemispheric dominance accompanied by a rare form of retarded language development].

    Science.gov (United States)

    Brunner, M; Wirth, G

    1986-04-01

    A severe and unusual form of retarded speech development in an eight-year old boy is analyzed as "right-hemispheric speech" against the background of neuropsychological theories on the specialisation of the cerebral hemispheres and considered in connection with the development of hemispheric dominance. A plan for therapy and teacher counselling is derived from this analysis. The influence of this retarded speech development on the acquisition of reading and writing is also touched upon.

  16. The Importance of Drains for the Larval Development of Lymphatic Filariasis and Malaria Vectors in Dar es Salaam, United Republic of Tanzania

    Science.gov (United States)

    Castro, Marcia C.; Kanamori, Shogo; Kannady, Khadija; Mkude, Sigsbert; Killeen, Gerry F.; Fillinger, Ulrike

    2010-01-01

    Background Dar es Salaam has an extensive drain network, mostly with inadequate water flow, blocked by waste, causing flooding after rainfall. The presence of Anopheles and Culex larvae is common, which is likely to impact the transmission of lymphatic filariasis and malaria by the resulting adult mosquito populations. However, the importance of drains as larval habitats remains unknown. Methodology Data on mosquito larval habitats routinely collected by the Urban Malaria Control Program (UMCP) and a special drain survey conducted in 2006 were used to obtain a typology of habitats. Focusing on drains, logistic regression was used to evaluate potential factors impacting the presence of mosquito larvae. Spatial variation in the proportion of habitats that contained larvae was assessed through the local Moran's I indicator of spatial association. Principal Findings More than 70% of larval habitats in Dar es Salaam were human-made. Aquatic habitats associated with agriculture had the highest proportion of Anopheles larvae presence and the second highest of Culex larvae presence. However, the majority of aquatic habitats were drains (42%), and therefore, 43% (1,364/3,149) of all culicine and 33% (320/976) of all anopheline positive habitats were drains. Compared with drains where water was flowing at normal velocity, the odds of finding Anopheles and Culex larvae were 8.8 and 6.3 (pcontrol efforts of those diseases. PMID:20520797

  17. Developing a cognitive behavioral therapy manual for delayed sleep-wake phase disorder.

    Science.gov (United States)

    Jansson-Fröjmark, Markus; Danielsson, Katarina; Markström, Agneta; Broman, Jan-Erik

    2016-11-01

    This article reports the development of a treatment protocol, based on cognitive behavioral therapy (CBT) principles, for delayed sleep-wake phase disorder (DSWPD). The protocol consists of psycho-education, presenting a CBT model for DSWPD, case formulation, motivational interviewing, registering sleep in a diary, strategies to improve the rhythm of sleep and wakefulness, relaxation training, cognitive restructuring, strategies to cope with daytime symptoms, constructing an individualized CBT program, and learning how to deal with relapses. Qualitative data, focusing on how the patients perceived the protocol, were collected within the realm of a trial exploring the efficacy of the protocol. These findings highlighted several advantages but also disadvantages of the therapy. It is our hope that this paper might act as a platform for further clinical work and future research efforts in patients with DSWPD.

  18. Reduced Mid1 expression and delayed neuromotor development in daDREAM transgenic mice

    Directory of Open Access Journals (Sweden)

    Mara eDierssen

    2012-05-01

    Full Text Available DREAM (downstream regulatory element antagonist modulator is a Ca2+-binding protein that binds DNA and represses transcription in a Ca2+-dependent manner. Previous work has shown a role for DREAM in cerebellar function regulating the expression of the sodium/calcium exchanger 3 (NCX3 in cerebellar granular neurons to control Ca2+ homeostasis and survival of these neurons. To achieve a global view of the genes regulated by DREAM in the cerebellum, we performed a genome-wide analysis in transgenic cerebellum expressing a Ca2+-insensitive/CREB-independent dominant active mutant DREAM (daDREAM. Here we show that DREAM regulates the expression of the midline 1 (Mid1 gene early after birth. As a consequence, daDREAM mice exhibit a significant shortening of the rostro-caudal axis of the cerebellum and a severe delay in neuromotor development early after birth. Our results indicate a role for DREAM in cerebellar function.

  19. Post onset, oral rapamycin treatment delays development of mitochondrial encephalopathy only at supramaximal doses.

    Science.gov (United States)

    Felici, Roberta; Buonvicino, Daniela; Muzzi, Mirko; Cavone, Leonardo; Guasti, Daniele; Lapucci, Andrea; Pratesi, Sara; De Cesaris, Francesco; Luceri, Francesca; Chiarugi, Alberto

    2017-05-01

    Mitochondrial encephalopathies are fatal, infantile neurodegenerative disorders caused by a deficit of mitochondrial functioning, for which there is urgent need to identify efficacious pharmacological treatments. Recent evidence shows that rapamycin administered both intraperitoneally or in the diet delays disease onset and enhances survival in the Ndufs4 null mouse model of mitochondrial encephalopathy. To delineate the clinical translatability of rapamycin in treatment of mitochondrial encephalopathy, we evaluated the drug's effects on disease evolution and mitochondrial parameters adopting treatment paradigms with fixed daily, oral doses starting at symptom onset in Ndufs4 knockout mice. Molecular mechanisms responsible for the pharmacodynamic effects of rapamycin were also evaluated. We found that rapamycin did not affect disease development at clinically-relevant doses (0.5 mg kg(-1)). Conversely, an oral dose previously adopted for intraperitoneal administration (8 mg kg(-1)) delayed development of neurological symptoms and increased median survival by 25%. Neurological improvement and lifespan were not further increased when the dose raised to 20 mg kg(-1). Notably, rapamycin at 8 mg kg(-1) did not affect the reduced expression of respiratory complex subunits, as well as mitochondrial number and mtDNA content. This treatment regimen however significantly ameliorated architecture of mitochondria cristae in motor cortex and cerebellum. However, reduction of mTOR activity by rapamycin was not consistently found within the brain of knockout mice. Overall, data show the ability of rapamycin to improve ultrastructure of dysfunctional mitochondria and corroborate its therapeutic potential in mitochondrial disorders. The non-clinical standard doses required, however, raise concerns about its rapid and safe clinical transferability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Ambulatory EEG NeuroMonitor platform for engagement studies of children with development delays

    Science.gov (United States)

    Mahajan, Ruhi; Consul-Pacareu, Sergi; Abusaud, Mohammed; Sahadat, Md N.; Morshed, Bashir I.

    2013-05-01

    Engagement monitoring is crucial in many clinical and therapy applications such as early learning preschool classes for children with developmental delays including autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), or cerebral palsy; as it is challenging for the instructors to evaluate the individual responses of these children to determine the effectiveness of the teaching strategies due to the diverse and unique need of each child who might have difficulty in verbal or behavioral communication. This paper presents an ambulatory scalp electroencephalogram (EEG) NeuroMonitor platform to study brain engagement activities in natural settings. The developed platform is miniature (size: 2.2" x 0.8" x 0.36", weight: 41.8 gm with 800 mAh Li-ion battery and 3 snap leads) and low-power (active mode: 32 mA low power mode: under 5mA) with 2 channels (Fp1, Fp2) to record prefrontal cortex activities of the subject in natural settings while concealed within a headband. The signals from the electrodes are amplified with a low-power instrumentation amplifier; notch filtered (fc = 60Hz), then band-passed by a 2nd-order Chebyshev-I low-pass filter cascaded with a 2nd-order low-pass (fc = 125Hz). A PSoC ADC (16-bit, 256 sps) samples this filtered signal, and can either transmit it through a Class-2 Bluetooth transceiver to a remote station for real-time analysis or store it in a microSD card for offline processing. This platform is currently being evaluated to capture data in the classroom settings for engagement monitoring of children, aimed to study the effectiveness of various teaching strategies that will allow the development of personalized classroom curriculum for children with developmental delays.

  1. Recruitment of the barnacle Balanus amphitrite Darwin in a tropical estuary: implications of environmental perturbation, reproduction and larval ecology

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.; Anil, A.C.

    variations in recruitment, larval abundance, development and reproduction. Adult conditioning and inter-brood variations were important factors in the larval ecology of this organism. The results indicate that the impulsive release of larvae during breaks...

  2. Neutrophil apoptosis is delayed in an equine model of colitis: Implications for the development of systemic inflammatory response syndrome.

    Science.gov (United States)

    Anderson, S L; Singh, B

    2017-05-01

    Horses that develop colitis invariably exhibit signs of a systemic inflammatory response syndrome (SIRS). A significant contributor to the development of SIRS in human subjects is delayed neutrophil apoptosis, but this has not been specifically studied in horses. To determine the occurrence of ex vivo neutrophil apoptosis and its contribution to the development of SIRS in an equine colitis model. Experiment using a colitis model. Neutrophils were isolated before and after the induction of colitis using an oligofructose overdose model, placed into culture for 12 h or 24 h with or without lipopolysaccharide (LPS) at various concentrations, and assessed for the occurrence of apoptosis using Annexin V and propidium iodide staining with flow cytometric quantification. Levels of caspase-3, -8 and -9 activity were measured after 12 h of incubation in neutrophil lysates. Ex vivo neutrophil apoptosis was significantly delayed in neutrophils isolated after the induction of colitis (12-h incubation: P = 0.004; 24-h incubation: P = 0.003) with concomitant reductions in caspase-3, -8 and -9 activity (caspase-3: P = 0.004; caspase-8: P = 0.02; caspase-9: P = 0.02). Neutrophils isolated after the induction of colitis were refractory to LPS-delayed apoptosis. Neutrophil apoptosis was delayed with increasing cell concentration in vitro. The main limitation of the study is the that the exact mechanism for delayed neutrophil apoptosis following the induction of colitis was not fully elucidated. The data show that neutrophil apoptosis is delayed in horses following the induction of colitis as a result of interference with the intrinsic and extrinsic apoptotic pathways, which may contribute to the development of equine SIRS. Concurrent development of neutrophilia may contribute to a prolonged neutrophil lifespan through a concentration-dependent delay in apoptosis. © 2016 EVJ Ltd.

  3. Clonidine treatment delays postnatal motor development and blocks short-term memory in young mice.

    Science.gov (United States)

    Calvino-Núñez, Cristina; Domínguez-del-Toro, Eduardo

    2014-01-01

    During the development of the nervous system, the perinatal period is particularly sensitive as neuronal connections are still forming in the brain of the neonate. Alpha2-adrenergic receptors are overexpressed temporarily in proliferative zones in the developing brain, reaching a peak during the first postnatal week of life. Both stimulation and blocking of these receptors during this period alter the development of neural circuits, affecting synaptic connectivity and neuronal responses. They even affect motor and cognitive skills later on in the adult. It's especially important to look for the early neurological consequences resulting from such modifications, because they may go unnoticed. The main objective of the present study has been to reaffirm the importance of the maturation of alpha-adrenergic system in mice, by carrying out a comprehensive examination of motor, behavioral and cognitive effects in neonates, during early postnatal development, following chronic administration of the drug Clonidine, an alpha2 adrenergic system agonist. Our study shows that mice treated postnatally with clonidine present a temporal delay in the appearance of developmental markers, a slow execution of vestibular reflexes during first postnatal week of life and a blockade of the short term memory in the novel object recognition task. Shortly after the treatment the startle response is hyperreactive.

  4. Kauri seeds and larval somersaults

    DEFF Research Database (Denmark)

    Dupont, Steen Thorleif

    2012-01-01

    The trunk morphology of the larvae of the kauri pine (Agathis) seed infesting moth Agathiphaga is described using conventional, polarization, and scanning electron microscopy. The pine seed chamber formed by the larva is also described and commented on. The simple larval chaetotaxy includes more...... of the minute posture sensing setae, proprioceptors, than expected from the lepidopteran larval ground plan. The excess of proprioceptors is suggested to be necessary for sensory input concerning the larval posture within the seed chamber. The trunk musculature includes an autapomorphic radial ventral...... musculature made up of unique multisegmental muscles. The combined presence of additional proprioceptors and the unique ventral musculature is proposed to be related to the larval movement within the confined space of the seed chamber, especially to a proposed somersault movement that allows the larva...

  5. Transcriptomic analysis of neuropeptides and peptide hormones in the barnacle Balanus amphitrite: evidence of roles in larval settlement.

    Science.gov (United States)

    Yan, Xing-Cheng; Chen, Zhang-Fan; Sun, Jin; Matsumura, Kiyotaka; Wu, Rudolf S S; Qian, Pei-Yuan

    2012-01-01

    The barnacle Balanus amphitrite is a globally distributed marine crustacean and has been used as a model species for intertidal ecology and biofouling studies. Its life cycle consists of seven planktonic larval stages followed by a sessile juvenile/adult stage. The transitional processes between larval stages and juveniles are crucial for barnacle development and recruitment. Although some studies have been conducted on the neuroanatomy and neuroactive substances of the barnacle, a comprehensive understanding of neuropeptides and peptide hormones remains lacking. To better characterize barnacle neuropeptidome and its potential roles in larval settlement, an in silico identification of putative transcripts encoding neuropeptides/peptide hormones was performed, based on transcriptome of the barnacle B. amphitrite that has been recently sequenced. Potential cleavage sites andstructure of mature peptides were predicted through homology search of known arthropod peptides. In total, 16 neuropeptide families/subfamilies were predicted from the barnacle transcriptome, and 14 of them were confirmed as genuine neuropeptides by Rapid Amplification of cDNA Ends. Analysis of peptide precursor structures and mature sequences showed that some neuropeptides of B. amphitrite are novel isoforms and shared similar characteristics with their homologs from insects. The expression profiling of predicted neuropeptide genes revealed that pigment dispersing hormone, SIFamide, calcitonin, and B-type allatostatin had the highest expression level in cypris stage, while tachykinin-related peptide was down regulated in both cyprids and juveniles. Furthermore, an inhibitor of proprotein convertase related to peptide maturation effectively delayed larval metamorphosis. Combination of real-time PCR results and bioassay indicated that certain neuropeptides may play an important role in cypris settlement. Overall, new insight into neuropeptides/peptide hormones characterized in this study shall

  6. Transcriptomic analysis of neuropeptides and peptide hormones in the barnacle Balanus amphitrite: evidence of roles in larval settlement.

    Directory of Open Access Journals (Sweden)

    Xing-Cheng Yan

    Full Text Available The barnacle Balanus amphitrite is a globally distributed marine crustacean and has been used as a model species for intertidal ecology and biofouling studies. Its life cycle consists of seven planktonic larval stages followed by a sessile juvenile/adult stage. The transitional processes between larval stages and juveniles are crucial for barnacle development and recruitment. Although some studies have been conducted on the neuroanatomy and neuroactive substances of the barnacle, a comprehensive understanding of neuropeptides and peptide hormones remains lacking. To better characterize barnacle neuropeptidome and its potential roles in larval settlement, an in silico identification of putative transcripts encoding neuropeptides/peptide hormones was performed, based on transcriptome of the barnacle B. amphitrite that has been recently sequenced. Potential cleavage sites andstructure of mature peptides were predicted through homology search of known arthropod peptides. In total, 16 neuropeptide families/subfamilies were predicted from the barnacle transcriptome, and 14 of them were confirmed as genuine neuropeptides by Rapid Amplification of cDNA Ends. Analysis of peptide precursor structures and mature sequences showed that some neuropeptides of B. amphitrite are novel isoforms and shared similar characteristics with their homologs from insects. The expression profiling of predicted neuropeptide genes revealed that pigment dispersing hormone, SIFamide, calcitonin, and B-type allatostatin had the highest expression level in cypris stage, while tachykinin-related peptide was down regulated in both cyprids and juveniles. Furthermore, an inhibitor of proprotein convertase related to peptide maturation effectively delayed larval metamorphosis. Combination of real-time PCR results and bioassay indicated that certain neuropeptides may play an important role in cypris settlement. Overall, new insight into neuropeptides/peptide hormones characterized in

  7. Transcriptomic analysis of neuropeptides and peptide hormones in the barnacle Balanus amphitrite: evidence of roles in larval settlement.

    KAUST Repository

    Yan, Xing-Cheng

    2012-10-02

    The barnacle Balanus amphitrite is a globally distributed marine crustacean and has been used as a model species for intertidal ecology and biofouling studies. Its life cycle consists of seven planktonic larval stages followed by a sessile juvenile/adult stage. The transitional processes between larval stages and juveniles are crucial for barnacle development and recruitment. Although some studies have been conducted on the neuroanatomy and neuroactive substances of the barnacle, a comprehensive understanding of neuropeptides and peptide hormones remains lacking. To better characterize barnacle neuropeptidome and its potential roles in larval settlement, an in silico identification of putative transcripts encoding neuropeptides/peptide hormones was performed, based on transcriptome of the barnacle B. amphitrite that has been recently sequenced. Potential cleavage sites andstructure of mature peptides were predicted through homology search of known arthropod peptides. In total, 16 neuropeptide families/subfamilies were predicted from the barnacle transcriptome, and 14 of them were confirmed as genuine neuropeptides by Rapid Amplification of cDNA Ends. Analysis of peptide precursor structures and mature sequences showed that some neuropeptides of B. amphitrite are novel isoforms and shared similar characteristics with their homologs from insects. The expression profiling of predicted neuropeptide genes revealed that pigment dispersing hormone, SIFamide, calcitonin, and B-type allatostatin had the highest expression level in cypris stage, while tachykinin-related peptide was down regulated in both cyprids and juveniles. Furthermore, an inhibitor of proprotein convertase related to peptide maturation effectively delayed larval metamorphosis. Combination of real-time PCR results and bioassay indicated that certain neuropeptides may play an important role in cypris settlement. Overall, new insight into neuropeptides/peptide hormones characterized in this study shall

  8. Larval development and settling of Macoma balthica in a large-scale mesocosm experiment at different fCO2 levels

    Directory of Open Access Journals (Sweden)

    A. Jansson

    2015-12-01

    Full Text Available Anthropogenic carbon dioxide (CO2 emissions are causing severe changes in the global inorganic carbon balance of the oceans. Associated ocean acidification is expected to impose a major threat to marine ecosystems worldwide, and it is also expected to be amplified in the Baltic Sea where the system is already at present exposed to relatively large natural seasonal and diel pH fluctuations. The response of organisms to future ocean acidification has primarily been studied in single-species experiments, whereas the knowledge of community-wide responses is still limited. To study responses of the Baltic Sea pelagic community to a range of future CO2-scenarios, six ∼ 55 m3 pelagic mesocosms were deployed in the northern Baltic Sea in June 2012. In this specific study we focused on the tolerance, development and subsequent settlement process of the larvae of the benthic key-species Macoma balthica when exposed to different levels of future CO2. We found that the settling of M. balthica was delayed along the increasing CO2 gradient of the mesocosms. Also, when exposed to increasing CO2 levels larvae settled at a larger size, indicating a developmental delay. With on-going climate change, both the frequency and extent of regularly occurring high CO2 conditions is likely to increase, and a permanent pH decrease will likely occur. The strong impact of increasing CO2 levels on early-stage bivalves is alarming as these stages are crucial for sustaining viable populations, and a failure in their recruitment would ultimately lead to negative effects on the population.

  9. Larval development and settling of Macoma balthica in a large-scale mesocosm experiment at different fCO2 levels

    Science.gov (United States)

    Jansson, A.; Lischka, S.; Boxhammer, T.; Schulz, K. G.; Norkko, J.

    2015-12-01

    Anthropogenic carbon dioxide (CO2) emissions are causing severe changes in the global inorganic carbon balance of the oceans. Associated ocean acidification is expected to impose a major threat to marine ecosystems worldwide, and it is also expected to be amplified in the Baltic Sea where the system is already at present exposed to relatively large natural seasonal and diel pH fluctuations. The response of organisms to future ocean acidification has primarily been studied in single-species experiments, whereas the knowledge of community-wide responses is still limited. To study responses of the Baltic Sea pelagic community to a range of future CO2-scenarios, six ∼ 55 m3 pelagic mesocosms were deployed in the northern Baltic Sea in June 2012. In this specific study we focused on the tolerance, development and subsequent settlement process of the larvae of the benthic key-species Macoma balthica when exposed to different levels of future CO2. We found that the settling of M. balthica was delayed along the increasing CO2 gradient of the mesocosms. Also, when exposed to increasing CO2 levels larvae settled at a larger size, indicating a developmental delay. With on-going climate change, both the frequency and extent of regularly occurring high CO2 conditions is likely to increase, and a permanent pH decrease will likely occur. The strong impact of increasing CO2 levels on early-stage bivalves is alarming as these stages are crucial for sustaining viable populations, and a failure in their recruitment would ultimately lead to negative effects on the population.

  10. A new Synbranchus (Teleostei: Synbranchiformes: Synbranchidae from ilha de Marajó, Pará, Brazil, with notes on its reproductive biology and larval development

    Directory of Open Access Journals (Sweden)

    Sandra E. Favorito

    Full Text Available Synbranchus lampreia, new species, is described from rio Goiapi, Marajó Island, Pará, northern Brazil. It differs from the other two described species of the genus by its color pattern, which consists of large roundish black blotches scattered over a light brown or yellowish ground pigmentation and presence of inconspicuous brown small spots distributed among the large dark spots. The species is further distinguished from S. marmoratus by a higher number of vertebrae and from S. madeira by a shorter postanal length. Information about reproductive aspects is provided and larval stages are described and illustrated.

  11. Development and validation of dissolution testings in acidic media for rabeprazole sodium delayed-release capsules.

    Science.gov (United States)

    Tan, Yinhe; Si, Xiaoqing; Zhong, Lulu; Feng, Xin; Yang, Xinmin; Huang, Min; Wu, Chuanbin

    2016-10-01

    Rabeprazole sodium (RAB) dissolved in acidic media is accompanied by its degradation in the course of dissolution testing. To develop and establish the accumulative release profiles of ACIPHEX(®) Sprinkle (RAB) delayed-release capsules (ACIPHEX(®) Sprinkle) in acidic media using USP apparatus 2 (paddle apparatus) as a dissolution tester, the issues of determination of accumulative release amount of RAB in these acidic media and interference of hydroxypropylmethyl cellulose phthalate were solved by adding appropriate hydrochloric acid (HCl) into dissolution samples coupled with centrifugation so as to remove the interference and form a solution of degradation products of RAB, which is of a considerably stable ultraviolet (UV) absorbance at the wavelength of 298 nm within 2.0 h. Therefore, the accumulative release amount of RAB in dissolution samples at each sample time points could be determined by UV-spectrophotometry, and the accumulative release profiles of ACIPHEX(®) Sprinkle in the media of pH 1.0, pH 6.0, and pH 6.8 could be established. The method was validated per as the ICH Q2 (R1) guidelines and demonstrated to be adequate for quality control of ACIPHEX(®) Sprinkle and the accumulative release profiles can be used as a tool to guide the formulation development and quality control of a generic drug for ACIPHEX(®) Sprinkle.

  12. Effects of dust, formaldehyde and delayed feeding on early postnatal development of broiler chickens.

    Science.gov (United States)

    de Gouw, Pieter; van de Ven, Lotte J F; Lourens, Sander; Kemp, Bas; van den Brand, Henry

    2017-06-01

    We investigated effects of perinatal exposure to dust or formaldehyde and the moment of first feed intake after hatching on broiler chicken development during the first week of life. Four environmental treatments were used from 468 until 512h of incubation: control (CONT), heat treated dust (HTD), untreated dust (UTD) or formaldehyde disinfection (FORM). After hatching, all chickens were assigned to 1 of 2 feeding treatments: early feeding (EF; feed and water available in the hatcher) or delayed feeding (DF). After 512h of incubation (day 0), chickens were reared until day 7 of age. In DF chickens, body weight (BW), yolk free body mass (YFBM) and relative liver weight did not differ among environmental treatments at day 0. However, in EF chickens BW at day 0 was greater in HTD chickens than in UTD and FORM chickens. YFBM in EF chickens at day 0 was greater when chickens were exposed to HTD compared to the other environmental treatments. In EF chickens, relative liver weight was greater in HTD chickens than in FORM. In DF chickens, BW at day 0 was positively related with hatching time (HT). In EF chickens, YFBM was positively related to HT. Residual yolk weight at day 0 was positively related with HT, whereas relative liver weight and microbicidal capacity were negatively related with HT. This study demonstrated that formaldehyde and dust during the hatching phase affect broiler chicken development at pulling from the incubator, but not at day 7. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Are cognitive "insomnia" processes involved in the development and maintenance of delayed sleep wake phase disorder?

    Science.gov (United States)

    Richardson, Cele E; Gradisar, Michael; Barbero, Sebastian C

    2016-04-01

    Although individuals with delayed sleep wake phase disorder (DSWPD) and chronic insomnia disorder (CID) share many of the same phenomenological experiences, theories relating to the development and maintenance of these disorders are distinct in focus. Unlike CID, theory relating to DSWPD is primarily physiologically based and assumes almost no cognitive pathway. However, recent research findings suggest that individuals with DSWPD also display many of the sleep-disordered cognitive processes that were previously assumed to be unique to the insomnia experience. As such, this review aims to summarise current research findings to address the question "Could cognitive processes be involved in the development and maintenance of DSWPD?" In particular, the presence of cognitive and physiological pre-sleep arousal, sleep-related attentional bias, distorted perception of sleep and daytime functioning, dysfunctional beliefs and safety behaviours will be investigated. As this emerging area of research requires a stronger evidence base, we highlight suggestions for future investigation and provide preliminary practice points for clinicians assessing and treating "insomnia" in patients with DSWPD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Evolved differences in larval social behavior mediated by novel pheromones.

    Science.gov (United States)

    Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

    2014-12-12

    Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects.

  15. 可口革囊星虫(Phascolosoma esculenta)胚胎及幼虫发育研究%STUDY ON THE EMBRYONIC AND LARVAL DEVELOPMENT OF PHASCOLOSOMA ESCULENTA

    Institute of Scientific and Technical Information of China (English)

    金春华; 竺俊全; 许式见; 王伟

    2011-01-01

    To elucidate the embryonic and larval development of Phascolosoma esculenta, fertilized eggs of P. esculenta by artificial insemination were obtained and observed.. The processes of embryonic and larval development were observed, and the impact of salinity and pH value on the embryonic and larval development was investigated. The results indicated that the embryonic and larval development of P. esculenta undergo the following stages, i.e., zygote, cleavage,blastula, gastrula, trochosphere, pelagosphere, and finally juvenile worm stages. It took 7 hrs 10min after fertilization for an egg developed into trochosphere when the salinity is at 23.0, pH at 8.1-8.2, and water temperature at 28-29℃. 45.5h is needed for finishing embryonic development after fertilization. The optimal salinity and pH for embryonic development was 17.10-30.15 and 7.40-8.56, respectively. It took 16-18 days for pelagosphera larva to develop into juvenile worm.The trochosphere, which had a long apical tuft of cilia with a pair of red eyespots at the anterior part of the back, fed on its own yolk sac, lived a planktonic life and exhibited phototaxis. The pelagosphera larva, consisting of a collar-like head and saccular trunk and with a pair of red eyespots located at the rear of head, had a pelagic living at early-middle stage and then altered to a benthonic living at later stage. Juvenile worm lived a benthonic life and mainly fed on single-cell planktonic mircoalgae. The cleavage pattern of P. esculenta was spiral and holoblastic and the larval development pattern was indirect.%采用人工授精的方法获得受精卵,在人工培育条件下观察了可口革囊星虫胚胎及幼虫发育过程及其盐度和pH对胚胎发育的影响,探究可口革囊星虫胚胎及幼虫发育规律.结果表明,可口革囊星虫胚胎及幼虫发育过程为:受精卵→卵裂→囊胚→原肠胚→担抡幼虫→海球幼虫→稚虫.在水温28-29℃、盐度23、pH 8.1-8.2条件下,受精后7h 10

  16. Insecticidal effects of extracts of seven plant species on larval development, alpha-amylase activity and offspring production of Tribolium castaneum (Herbst) (Insecta: Coleoptera: Tenebrionidae).

    Science.gov (United States)

    Jbilou, R; Amri, H; Bouayad, N; Ghailani, N; Ennabili, A; Sayah, F

    2008-03-01

    Bioinsecticidal effects of methanol extracts from seven plant species on Tribolium castaneum were investigated. Centaurium erythraea, Peganum harmala, Ajuga iva, Aristolochia baetica, Pteridium aquilinum and Raphanus raphanistrum extracts inhibit growth of larvae. C. erythraea was the most toxic with 63% mortality 10 days after treatment, followed by P. harmala with 58%. C. erythraea and P. aquilinum reduce the emergence rate respectively of 66% and 19%. The duration of larval period was shortened by Launaea arborescens, P. aquilinum and A. iva extracts, whereas R. raphanistrum and P. harmala extracts extend the larval period when compared to the control. Extracts of C. erythraea, P. harmala, A. iva and A. baetica inhibited F1 progeny production. Larvae possess three alpha-amylase isoforms as determined by SDS-PAGE. Larvae fed on treated diet had lower alpha-amylase activity than larvae feed on untreated diet. C. erythraea and P. harmala are the most potent extracts. These plant extracts could be useful to reduce seed damage caused by this pest species.

  17. Newly-discovered muscle in the larva of Patella coerulea (Mollusca, Gastropoda) suggests the presence of a larval extensor

    NARCIS (Netherlands)

    Damen, Peter; Dictus, Wim J.A.G.

    2002-01-01

    The development of the muscular system of the gastropod mollusc Patella has been thoroughly studied. As a result, two larval retractors, the main and accessory larval retractor, had been described in the larva of Patella. These muscles were supposed to be responsible for the retraction of the larval

  18. Newly-discovered muscle in the larva of Patella coerulea (Mollusca, Gastropoda) suggests the presence of a larval extensor

    NARCIS (Netherlands)

    Damen, Peter; Dictus, Wim J.A.G.

    2002-01-01

    The development of the muscular system of the gastropod mollusc Patella has been thoroughly studied. As a result, two larval retractors, the main and accessory larval retractor, had been described in the larva of Patella. These muscles were supposed to be responsible for the retraction of the larval

  19. Chloroquine neither eliminates liver stage parasites nor delays their development in a murine Chemoprophylaxis Vaccination model

    Directory of Open Access Journals (Sweden)

    Tejram eSahu

    2015-04-01

    Full Text Available Chemoprophylaxis Vaccination (CVac confers long lasting sterile protection against homologous parasite strains in humans, and involves inoculation of infectious sporozoites under drug cover. CVac using the drug chloroquine (CQ induces pre-erythrocytic immunity in humans that includes antibody to sporozoites and T-cell responses to liver stage parasites. The mechanism by which CVac with CQ induces strong protective immunity is not understood as untreated infections do not confer protection. CQ kills blood stage parasites, but its effect on liver stage parasites is poorly studied. Here we hypothesized that CQ may prolong or perturb liver stage development of Plasmodium, as a potential explanation for enhanced pre-erythrocytic immune responses. Balb/c mice with or without CQ prophylaxis were infected with sporozoite forms of a luciferase-expressing rodent parasite, Plasmodium yoelii-Luc (Py-Luc. Mice that received primaquine (PQ, a drug that kills liver stage parasites, served as a positive control of drug effect. Parasite burden in liver was measured both by bioluminescence and by qRT-PCR quantification of parasite transcript. Time to appearance of parasites in the blood was monitored by microscopic analysis of Giemsa-stained thick and thin blood smears. The parasite load in livers of CQ-treated and untreated mice did not significantly differ at any of the time points studied. Parasites appeared in the blood smears of both CQ-treated and untreated mice 3 days after infection. Taken together, our findings confirm that CQ neither eliminates liver stage parasites nor delays their development. Further investigations into the mechanism of CQ-induced protection after CVac are required, and may give insights relevant to drug and vaccine development.

  20. Enhanced insulin sensitivity in prepubertal children with constitutional delay of growth and development.

    Science.gov (United States)

    Wilson, Dyanne A; Hofman, Paul L; Miles, Harriet L; Sato, Tim A; Billett, Nathalie E; Robinson, Elizabeth M; Cutfield, Wayne S

    2010-02-01

    To test the hypothesis that prepubertal children with presumed constitutional delay of growth and development (CDGD) have enhanced insulin sensitivity and, therefore, insulin sensitivity is associated with later onset of puberty. Twenty-one prepubertal children with presumed CDGD and 23 prepubertal control children, underwent a frequently sampled intravenous glucose tolerance test to evaluate insulin sensitivity and other markers of insulin, glucose, and growth regulation. Children in the CDGD group were shorter and leaner than control subjects. Children with presumed CDGD were 40% more insulin sensitive (17.0 x 10(-4) min(-1)/[mU/L] versus 12.1 x 10(-4) min(-1)/[mU/L]; P = .0006) and had reduced acute insulin response, thus maintaining euglycemia (216 mU/L versus 330 mU/L; P = .02) compared with control subjects. In addition, the CDGD group had lower serum insulin-like growth factor binding protein 3 levels (3333 ng/mL versus 3775 ng/mL; P = .0004) and a trend toward lower serum insulin-like growth factor-II levels (794 ng/mL versus 911 ng/mL; P = .06). Prepubertal children with presumed CDGD have enhanced insulin sensitivity, supporting the hypothesis that insulin sensitivity is associated with timing of puberty. It may signify long-term biological advantages with lower risk of metabolic syndrome and malignancy. Copyright 2010 Mosby, Inc. All rights reserved.

  1. Larval morphology of Metaphycus flavus and its role in host attachment and larval cannibalism.

    Science.gov (United States)

    Tena, A; Kapranas, A; Walker, G P; Garcia-Marí, F; Luck, R F

    2011-06-01

    Metaphycus flavus (Howard) (Hymenoptera: Encyrtidae) is a facultatively gregarious endoparasitoid of soft scales (Hemiptera: Coccidae). When it develops in superparasitised hosts, the larvae often attack and consume brood mates six or more days post oviposition. Under our laboratory conditions (25±1°C and 14 hours of light followed by 18±1°C and ten hours of darkness in 50-70% R.H.), M. flavus eggs hatched three days after oviposition. Measurements of the mandibles and tentorium indicate there are four larval instars, and M. flavus reaches the fourth instar by day six post oviposition, and pupates on day eight. Thus, cannibalism among M. flavus larvae occurs during the fourth instar. During this instar, M. flavus larvae separate from their attachment to the scale cuticle, to which they were tethered by a respiratory structure during the previous three larval instars. Once detached, they are free to move within the scale, which increases the probability of larval encounters and aggressive behaviours. Moreover, the mandibles of the fourth instar are better adapted for fighting than are those of the first three larval instars, since they are larger and more sclerotized. The cranium and mouthparts of M. flavus have four different types of sensory organs, some of which are almost certainly olfactory, an unexpected function for a larva that presumably is surrounded by an aqueous medium where gustatory sensilla would seem to be more appropriate. The cranium also bears two pairs of what appear to be secretory pores.

  2. Development of a new Delayed Memory Index for the WMS-III.

    Science.gov (United States)

    Tulsky, David S; Chelune, Gordon J; Price, Larry R

    2004-06-01

    This paper presents the Delayed Memory Index (DMI) as an alternative to the General Memory Index (GMI) of the Weschler Memory Scale-Third Edition (WMS-III). The WMS-III Immediate Memory Index (IMI) and the GMI are not parallel in structure, making a direct comparison between these index scores (i.e., immediate vs. delayed memory variables) difficult. The IMI is composed of the sum of scaled scores of four subtests (Logical Memory I, Verbal Paired Associates I, Faces I, and Family Pictures I) while the GMI is composed of the sum of scaled scores of five subtests (Logical Memory II, Verbal Paired Associates II, Faces II, Family Pictures II and Auditory Recognition Delayed). Inclusion of Auditory Recognition Delayed in the GMI is also problematic as it is highly skewed and limited by extreme ceiling effects (see Tulsky, Chiaravalloti, Palmer, & Chelune, 2003). To remedy these problems, we present a new index score that does not include auditory recognition, the Delayed Memory Index. Normative tables for the new Delayed Memory Index based on the inclusion of the Faces subtest, or alternatively the Visual Reproduction subtest, are presented, and initial estimates of their psychometric properties are described.

  3. Effects of music therapy in the treatment of children with delayed speech development - results of a pilot study.

    Science.gov (United States)

    Gross, Wibke; Linden, Ulrike; Ostermann, Thomas

    2010-07-21

    Language development is one of the most significant processes of early childhood development. Children with delayed speech development are more at risk of acquiring other cognitive, social-emotional, and school-related problems. Music therapy appears to facilitate speech development in children, even within a short period of time. The aim of this pilot study is to explore the effects of music therapy in children with delayed speech development. A total of 18 children aged 3.5 to 6 years with delayed speech development took part in this observational study in which music therapy and no treatment were compared to demonstrate effectiveness. Individual music therapy was provided on an outpatient basis. An ABAB reversal design with alternations between music therapy and no treatment with an interval of approximately eight weeks between the blocks was chosen. Before and after each study period, a speech development test, a non-verbal intelligence test for children, and music therapy assessment scales were used to evaluate the speech development of the children. Compared to the baseline, we found a positive development in the study group after receiving music therapy. Both phonological capacity and the children's understanding of speech increased under treatment, as well as their cognitive structures, action patterns, and level of intelligence. Throughout the study period, developmental age converged with their biological age. Ratings according to the Nordoff-Robbins scales showed clinically significant changes in the children, namely in the areas of client-therapist relationship and communication. This study suggests that music therapy may have a measurable effect on the speech development of children through the treatment's interactions with fundamental aspects of speech development, including the ability to form and maintain relationships and prosodic abilities. Thus, music therapy may provide a basic and supportive therapy for children with delayed speech development

  4. Effects of Sampling Context on the Finite Verb Production of Children with and without Delayed Language Development

    Science.gov (United States)

    Sealey, Linda R.; Gilmore, Susan E.

    2008-01-01

    Informal language sampling is ubiquitous in the study of developing grammatical abilities in children with and without delayed language, including study of grammatical abilities in the area of finite verb production. Finite verbs are particularly important to assess as they appear to be the grammatical morphemes most vulnerable to error in the…

  5. OJKO-project : Longitudinal study on the development of young children with a serious cognitive and motor developmental delay

    NARCIS (Netherlands)

    Schalen, Gertruud Henrike; Visser, Linda; van der Putten, Annette

    2015-01-01

    Recently, a longitudinal project on the development of children with a serious cognitive and motor developmental delay has started in Belgium and the Netherlands. The aims of this study are to evaluate the cognitive, motor, communicative and social-emotional abilities of young children with a severe

  6. Delayed early primary visual pathway development in premature infants: high density electrophysiological evidence.

    Directory of Open Access Journals (Sweden)

    Emmanuel Tremblay

    Full Text Available In the past decades, multiple studies have been interested in developmental patterns of the visual system in healthy infants. During the first year of life, differential maturational changes have been observed between the Magnocellular (P and the Parvocellular (P visual pathways. However, few studies investigated P and M system development in infants born prematurely. The aim of the present study was to characterize P and M system maturational differences between healthy preterm and fullterm infants through a critical period of visual maturation: the first year of life. Using a cross-sectional design, high-density electroencephalogram (EEG was recorded in 31 healthy preterms and 41 fullterm infants of 3, 6, or 12 months (corrected age for premature babies. Three visual stimulations varying in contrast and spatial frequency were presented to stimulate preferentially the M pathway, the P pathway, or both systems simultaneously during EEG recordings. Results from early visual evoked potentials in response to the stimulation that activates simultaneously both systems revealed longer N1 latencies and smaller P1 amplitudes in preterm infants compared to fullterms. Moreover, preterms showed longer N1 and P1 latencies in response to stimuli assessing the M pathway at 3 months. No differences between preterms and fullterms were found when using the preferential P system stimulation. In order to identify the cerebral generator of each visual response, distributed source analyses were computed in 12-month-old infants using LORETA. Source analysis demonstrated an activation of the parietal dorsal region in fullterm infants, in response to the preferential M pathway, which was not seen in the preterms. Overall, these findings suggest that the Magnocellular pathway development is affected in premature infants. Although our VEP results suggest that premature children overcome, at least partially, the visual developmental delay with time, source analyses reveal

  7. Muscle development and body growth in larvae and early post-larvae of shi drum, Umbrina cirrosa L., reared under different larval photoperiod: muscle structural and ultrastructural study.

    Science.gov (United States)

    Ayala, Maria D; Abellán, Emilia; Arizcun, Marta; García-Alcázar, Alicia; Navarro, F; Blanco, Alfonso; López-Albors, Octavio M

    2013-08-01

    Shi drum specimens were maintained under four different photoperiod regimes: a natural photoperiod regime (16L:8D), constant light (24L), equal durations of light and dark (12L:12D) and a reduced number of daylight hours (6L:18D) from hatching until the end of larval metamorphosis. Specimens were then kept under natural photoperiod conditions until 111 days post-hatching. Muscle and body parameters were studied. During the vitelline phase, there was little muscle growth and no photoperiod effects were reported; however, a monolayer of red muscle and immature white muscle fibres were observed in the myotome. At hatching, external cells (presumptive myogenic cells) were already present on the surface of the red muscle. At the mouth opening, some presumptive myogenic cells appeared between the red and white muscles. At 20 days, new germinal areas were observed in the apical extremes of the myotome. At this stage, the 16L:8D group (followed by the 24L group) had the longest body length, the largest cross-sectional area of white muscle and the largest white muscle fibres. Conversely, white muscle hyperplasia was most pronounced in the 24L group. Metamorphosis was complete at 33 days in the 24L and 12L:12D groups. At this moment, both groups showed numerous myogenic precursors on the surface of the myotome as well as among the adult muscle fibres (mosaic hyperplastic growth). The 16L:8D group completed metamorphosis at 50 days, showing a similar degree of structural maturity in the myotome to that described in the 24L and 12L:12D groups at 33 days. When comparing muscle growth at the end of the larval period, hypertrophy was highest in the 16L:8D group, whereas hyperplasia was higher in the 24L and 16L:8D groups. At 111 days, all groups showed the adult muscle pattern typical of teleosts; however, the cross-sectional area of white muscle, white muscle fibre hyperplasia, body length and body weight were highest in the 24L group, followed by the 12L:12D group; white muscle

  8. Development of a regional tropospheric delay model for GPS-based navigation with emphasis to the Indian Region

    Science.gov (United States)

    Parameswaran, K.; Saha, Korak; Suresh Raju, C.

    2008-08-01

    The accuracy of Global Navigation Satellite System (GNSS), aimed to support precise positioning for aircraft navigation globally by coordinating different regional augmentation systems, is limited by the extent to which the atmospheric propagation delay of microwave signals can be modeled. An algorithm is developed for modeling the tropospheric delay based on mean meteorological parameters. A Region-specific Tropospheric Delay (RTD) model is developed exclusively for the Indian region using meteorological data from the Indian subcontinent, as a part of GPS Aided Geo Augmented Navigation (GAGAN) program. The applicability of this model is examined in the context of the global model used in Wide Area Augmentation System (WAAS), developed employing meteorological data mostly from North American continent, by comparing the estimated zenith tropospheric delay (ZTD) with those obtained from regional models employing measured atmospheric parameters at the surface. The rms deviation of ZTD estimated using RTD model from that of the surface model is found to be ˜5 cm. A further validation by comparing with GPS measurements from two IGS stations at Bangalore and Hyderabad showed that predictions made using the RTD model are within an rms deviation of ±5 cm while those using WAAS model is ±7 cm. Maximum value of the residual error for RTD model is ˜15 cm, which corresponds to a ˜0.5 m error in the vertical coordinates for the lowest satellite elevation angles usually encountered.

  9. Incidence and impact of axial malformations in larval bullfrogs (Rana catesbeiana) developing in sites polluted by a coal-burning power plants

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, W.A.; Congdon, J.; Ray, J.K. [Savannah River Ecology Laboratory, Aiken, SC (USA)

    2000-04-01

    Amphibian malformations have recently received much attention from the scientific community, but few studies have provided evidence linking environmental pollution to larval amphibian malformations in the field. The authors document an increased incidence of axial malformations in bullfrog larvae (Rana catesbeiana) inhabiting two sites contaminated with coal combustion wastes. In the polluted sites, 18 and 37% of larvae exhibited lateral curvatures of the spine, whereas zero and 4% of larvae from two reference sites had similar malformations. Larvae from the most heavily polluted site had significantly higher tissue concentrations of potentially toxic trace elements, including As, Cd, Se, Cu, Cr and V, compared with others from the reference sites. In addition, malformed larvae from the most contaminated site had decreased swimming speeds compared with those of normal larvae from the same site. It is hypothesized that the complex mixture of contaminants produced by coal combustion is responsible for the high incidence of malformations and associated effects on swimming performance.

  10. Incidence and impact of axial malformations in larval bullfrogs (Rana catesbeiana) developing in sites polluted by a coal-burning power plant

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, W.A.; Congdon, J.; Ray, J.K.

    2000-04-01

    Amphibian malformations have recently received much attention from the scientific community, but few studies have provided evidence linking environmental pollution to larval amphibian malformations in the field. The authors document an increased incidence of axial malformations in bullfrog larvae (Rana catesbeiana) inhabiting two sites contaminated with coal combustion wastes. In the polluted sites, 18 and 37% of larvae exhibited lateral curvatures of the spine, whereas zero and 4% of larvae from two reference sites had similar malformations. Larvae from the most heavily polluted site had significantly higher tissue concentrations of potentially toxic trace elements, including As, Cd, Se, Cu, Cr, and V, compared with conspecifics from the reference sites. In addition, malformed larvae from the cost contaminated site had decreased swimming speeds compared with those of normal larvae from the same site. The authors hypothesize that the complex mixture of contaminants produced by coal combustion is responsible for the high incidence of malformations and associated effects on swimming performance.

  11. Loss of LORELEI function in the pistil delays initiation but does not affect embryo development in Arabidopsis thaliana

    Science.gov (United States)

    Tsukamoto, Tatsuya

    2010-01-01

    Double fertilization, uniquely observed in plants, requires successful sperm cell delivery by the pollen tube to the female gametophyte, followed by migration, recognition and fusion of the two sperm cells with two female gametic cells. The female gametophyte not only regulates these steps but also controls the subsequent initiation of seed development. Previously, we reported that loss of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)-anchored protein, in the female reproductive tissues causes a delay in initiation of seed development. From these studies, however, it was unclear if embryos derived from fertilization of lre-5 gametophytes continued to lag behind wild-type during seed development. Additionally, it was not determined if the delay in initiation of seed development had any lingering effects during seed germination. Finally, it was not known if loss of LORELEI function affects seedling development given that LORELEI is expressed in eight-day-old seedlings. Here, we showed that despite a delay in initiation, lre-5/lre-5 embryos recover, becoming equivalent to the developing wild-type embryos beginning at 72 hours after pollination. Additionally, lre-5/lre-5 seed germination, and seedling and root development are indistinguishable from wild-type indicating that loss of LORELEI is tolerated, at least under standard growth conditions, in vegetative tissues. PMID:21051955

  12. Loss of LORELEI function in the pistil delays initiation but does not affect embryo development in Arabidopsis thaliana.

    Science.gov (United States)

    Tsukamoto, Tatsuya; Palanivelu, Ravishankar

    2010-11-01

    Double fertilization, uniquely observed in plants, requires successful sperm cell delivery by the pollen tube to the female gametophyte, followed by migration, recognition and fusion of the two sperm cells with two female gametic cells. The female gametophyte not only regulates these steps but also controls the subsequent initiation of seed development. Previously, we reported that loss of LORELEI, which encodes a putative glycosylphosphatidylinositol (GPI)-anchored protein, in the female reproductive tissues causes a delay in initiation of seed development. From these studies, however, it was unclear if embryos derived from fertilization of lre-5 gametophytes continued to lag behind wild type during seed development. Additionally, it was not determined if the delay in initiation of seed development had any lingering effects during seed germination. Finally, it was not known if loss of LORELEI function affects seedling development given that LORELEI is expressed in eight-day-old seedlings. Here, we showed that despite a delay in initiation, lre-5/lre-5 embryos recover, becoming equivalent to the developing wild-type embryos beginning at 72 hours after pollination. Additionally, lre-5/lre-5 seed germination, and seedling and root development are indistinguishable from wild type indicating that loss of LORELEI is tolerated, at least under standard growth conditions, in vegetative tissues.

  13. Larval exposure to 4-nonylphenol and 17β-estradiol affects physiological and behavioral development of seawater adaptation in Atlantic salmon smolts

    Science.gov (United States)

    Lerner, Darrren T.; Bjornsson, Bjorn Thrandur; McCormick, Stephen D.

    2007-01-01

    Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 μg L-1 NP (NP-L or NP-H, respectively), 2 μg L-1 17β-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K+-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long term, “organizational” effects on life-history events in salmonids.

  14. Larval exposure to 4-nonylphenol and 17beta-estradiol affects physiological and behavioral development of seawater adaptation in Atlantic salmon smolts.

    Science.gov (United States)

    Lerner, Darren T; Björnsson, Björn Thrandur; McCormick, Stephen D

    2007-06-15

    Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 microg L(-1) NP (NP-L or NP-H, respectively), 2 microg L(-1) 17beta-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K(+)-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long-term, "organizational" effects on life-history events in salmonids.

  15. Development of Some Larval Nematodes in Experimental and Natural Animal Hosts: An Insight into Development of Pathological Lesions vis-a-vis Host-Parasite Interactions

    Directory of Open Access Journals (Sweden)

    N. Chowdhury

    2013-01-01

    Full Text Available Infective third-stage larvae of three spiruroid nematodes, Ascarops strongylina and Physocephalus sexalatus of pigs and Spirocerca lupi of dogs, were recovered from 14 species of coprophagous beetles belonging to 4 different genera. These larvae were fed to rabbits and/or guinea pigs to study their development in these experimental hosts. Larvae of A. strongylina reached the adult stage in all rabbits and one guinea pig. The adult worms recovered in these hosts were 40% and 4%, respectively, and became diminutive in comparison to their natural hosts. The larvae of P. sexalatus became reencysted in the gastric wall of rabbits inducing marked pathological changes. The infective larvae of S. lupi became reencapsulated in the stomach wall of the rabbit and also showed development in the aortic wall. Adults of Toxocara canis of dog, collected from 5 different regions of the Indian subcontinent, varied significantly in size. The mouse passage of infective larvae of one of these types led to the recovery of the adults from the experimental dogs that were smaller in size and caused severe pathology in natural experimental hosts. Developmental effects shown in experimental hosts and host specificity are of value in understanding the evolution of nematode parasitism.

  16. Can adolescents learn self-control? Delay of gratification in the development of control over risk taking.

    Science.gov (United States)

    Romer, Daniel; Duckworth, Angela L; Sznitman, Sharon; Park, Sunhee

    2010-09-01

    Recent findings from developmental neuroscience suggest that the adolescent brain is too immature to exert control over impulsive drives, such as sensation seeking, that increase during adolescence. Using a discounting of delayed reward paradigm, this research examines the ability to delay gratification as a potential source of control over risk-taking tendencies that increase during adolescence. In addition, it explores the role of experience resulting from risk taking as well as future time perspective as contributors to the development of this ability. In a nationally representative sample (n = 900) of young people aged 14-22, a structural equation analysis shows that risk taking as assessed by use of three popular drugs (tobacco, marijuana, and alcohol) is inversely related to the ability to delay gratification. The relation is robust across gender, age, and different levels of sensation seeking. In addition, high sensation seekers exhibit dramatic age-related increase in delay of gratification, lending support to the hypothesis that engaging in risky behavior provides experience that leads to greater patience for long-term rewards. The findings support the conclusion that a complete understanding of the development of self-control must consider individual differences not easily explained by universal trends in brain maturation.

  17. Larval long-toed salamanders incur nonconsumptive effects in the presence of nonnative trout

    Science.gov (United States)

    Kenison, Erin K.; Litt, Andrea R.; Pilliod, David; McMahon, Thomas E.

    2016-01-01

    Predators can influence prey directly through consumption or indirectly through nonconsumptive effects (NCEs) by altering prey behavior, morphology, and life history. We investigated whether predator-avoidance behaviors by larval long-toed salamanders (Ambystoma macrodactylum) in lakes with nonnative trout result in NCEs on morphology and development. Field studies in lakes with and without trout were corroborated by experimental enclosures, where prey were exposed only to visual and chemical cues of predators. We found that salamanders in lakes with trout were consistently smaller than in lakes without trout: 38% lower weight, 24% shorter body length, and 29% shorter tail length. Similarly, salamanders in protective enclosures grew 2.9 times slower when exposed to visual and olfactory trout cues than when no trout cues were present. Salamanders in trout-free lakes and enclosures were 22.7 times and 1.48 times, respectively, more likely to metamorphose during the summer season than those exposed to trout in lakes and/or their cues. Observed changes in larval growth rate and development likely resulted from a facultative response to predator-avoidance behavior and demonstrate NCEs occurred even when predation risk was only perceived. Reduced body size and growth, as well as delayed metamorphosis, could have ecological consequences for salamander populations existing with fish if those effects carry-over into lower recruitment, survival, and fecundity.

  18. Development of an X-ray delay unit for correlation spectroscopy and pump-probe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Roseker, Wojciech

    2008-07-15

    Probing condensed matter on time scales ranging from femtoseconds to nanoseconds will be one of the key topics for future X-ray Free Electron Laser (XFEL) sources. The accessible time windows are, however, compromised by the intrinsic time structure of the sources. One way to overcome this limitation is the usage of a time delay unit. A prototype device capable of splitting an X-ray pulse into two adjustable fractions, delaying one of them with the aim to perform X-ray Photon Correlation Spectroscopy and pump-probe type studies was designed and manufactured. The device utilizes eight perfect crystals in vertical 90 scattering geometry. Its performance has been verified with 8.39 keV and 12.4 keV Xrays at various synchrotron sources. The measured throughput of the device with a Si(333) monochromator at 8.39 keV under ambient conditions is 0.6%. The stability was verified at 12.4 keV and operation without realignment and feedback was possible for more than 30 minutes. Time delays up to 2.95 ns have been achieved. The highest resolution achieved in an experiment was 15.4 ps, a value entirely determined by the diagnostics system. The influence of the delay unit optics on the coherence properties of the beam was investigated by means of Fraunhofer diffraction and static speckle analysis. The obtained high fringe visibility and contrast values larger than 23% indicate the feasibility of performing coherence based experiments with the delay line. (orig.)

  19. A unique case of mating behaviour in a Malagasy tree frog, Gephyromantis liber (Peracca, 1893), with observations on the larval development (Amphibia, Ranidae)

    NARCIS (Netherlands)

    Blommers-Schlösser, Rose M.A.

    1975-01-01

    The mating act in Gephyromantis liber and in other species of this genus differs from all other mating behaviour patterns known in Anura. The male settles with the ventral side of his thighs on the shoulders of the female, and oviposition starts without delay. The assumption is made that the femoral

  20. Cardiorespiratory ontogeny and response to environmental hypoxia of larval spiny lobster, Sagmariasus verreauxi.

    Science.gov (United States)

    Fitzgibbon, Quinn P; Ruff, Nicole; Battaglene, Stephen C

    2015-06-01

    Cardiorespiratory function is vital to an organism's ability to respond to environmental stress and analysis of cardiorespiratory capacity of species or life stages can elucidate vulnerability to climate change. Spiny lobsters have one of the most complex pelagic larval life cycles of any invertebrate and recently there has been an unexplained decline in post-larval recruitment for a number of species. We conducted the first analysis of the larval ontogeny of oxygen consumption, heart rate, maxilla 2 ventilation rate and oxyregulatory capacity of the spiny lobster, Sagmariasus verreauxi, to gain insight into their vulnerability to ocean change and to investigate life stage specific sensitivity to temperature-dependent oxygen limitation. In normoxia, heart and maxilla 2 ventilation rates increased in early larval development before declining, which we hypothesise is related to the transition from myogenic to neurogenic cardiac control. Maxilla 2 ventilation rate was sensitive to hypoxia at all larval stages, while heart rate was only sensitive to hypoxia in the late phyllosoma stages. Oxygen consumption conformed to environmental hypoxia at all larval stages. Spiny lobster larvae have limited respiratory control due to immature gas exchange physiology, compounded by their exceptionally large size. The lack of oxyregulatory ability suggests that all development stages are vulnerable to changes in sea temperature and oxygen availability. The synergetic stressors of increased temperature and reduced dissolved oxygen in the marine environment will diminish spiny lobster larval performance, increasing the challenge to achieve their extended larval life cycle, which may contribute to declines in post-larval recruitment.

  1. 人工养殖银鲳子代胚胎发育及仔稚幼鱼形态观察%Observation of embryonic,larval and juvenile development in Pampus argenteus offspring

    Institute of Scientific and Technical Information of China (English)

    施兆鸿; 彭士明; 王建钢; 孙鹏; 尹飞

    2011-01-01

    采用人工培育的子代银鲳(Pampus argentus)为亲本,对银鲳的胚胎及胚后各发育阶段的形态特征进行观察测量,以期为今后苗种培育和繁殖生物学研究提供参考资料.银鲳成熟卵子为端黄卵,单个油球,卵径(1.417±0.063)mm,油球径(0.575±0.031)mm.在水温(20.0±0.5)℃、盐度24±1,pH8.0~8.5条件下,受精卵经36 h孵化出膜.初孵仔鱼在水温19.0~24.0℃、盐度 23±1,pH8.0~8.5、光照2 000~3 000 lx条件下,经60 d培育成幼鱼.银鲳早期发育分前期仔鱼、后期仔鱼、稚鱼和幼鱼,前期仔鱼以卵黄囊吸收消化为主要形态特征;后期仔鱼分化出侧囊、食道、胃、幽门育囊和肝脏等消化器官,外形特征是鱼体腹两侧星状黑色素及金黄色斑点明显,背鳍和臀鳍鳍条原基出现,13日龄仔鱼全长(5.586±0.479)mm,体高((1.068±0.087)mm;稚鱼期消化器官进一步完善,脊索末端向上曲屈,随后尾下骨出现并且尾下骨末端与体轴倾斜,至35日龄尾下骨与体轴垂直,45日龄体高明显增高,全长(25.560±3.870)mm,体高(11.157±1.266)mm.幼鱼期胸鳍前端呈尖形,尾鳍上下两侧生长加快形成深叉状,鳞片完全长成,60 d时全长为(引.000±3.300)mm,体高达(19.750±1.620)mm,此时体形与成鱼已无差别.此外,本研究还对仔稚幼鱼的划分、鲳属鱼类中主要品种胚胎与仔稚鱼发育的异同点以及育苗中容易出现死亡的关键时期进行了分析探讨.%The embryonic, larval and juvenile development of the offspring obtained from cultured silver pomfret (Pampus argenteus) was observed, which contributed to the study of larvae rearing and breeding biology of pomfret.The eggs of silver pomfret were telolecithal, and had only one oil globule.The diameter of egg and oil globule were (1.417 ± 0.063) mm and (0.575 ± 0.031) mm, respectively.The hatching time was about 36 h after fertilization when the first larva was hatched at (20.0 ± 0.5) ℃, salinity 24 ± 1

  2. Spatial and temporal population genetic structure of four northeastern Pacific littorinid gastropods: the effect of mode of larval development on variation at one mitochondrial and two nuclear DNA markers.

    Science.gov (United States)

    Lee, Hyuk Je; Boulding, Elizabeth G

    2009-05-01

    We investigated the effect of development mode on the spatial and temporal population genetic structure of four littorinid gastropod species. Snails were collected from the same three sites on the west coast of Vancouver Island, Canada in 1997 and again in 2007. DNA sequences were obtained for one mitochondrial gene, cytochrome b (Cyt b), and for up to two nuclear genes, heat shock cognate 70 (HSC70) and aminopeptidase N intron (APN54). We found that the mean level of genetic diversity and long-term effective population sizes (N(e)) were significantly greater for two species, Littorina scutulata and L. plena, that had a planktotrophic larval stage than for two species, Littorina sitkana and L. subrotundata, that laid benthic egg masses which hatched directly into crawl-away juveniles. Predictably, two poorly dispersing species, L. sitkana and L. subrotundata, showed significant spatial genetic structure at an 11- to 65-km geographical scale that was not observed in the two planktotrophic species. Conversely, the two planktotrophic species had more temporal genetic structure over a 10-year interval than did the two direct-developing species and showed highly significant temporal structure for spatially pooled samples. The greater temporal genetic variation of the two planktotrophic species may have been caused by their high fecundity, high larval dispersal, and low but spatially correlated early survivorship. The sweepstakes-like reproductive success of the planktotrophic species could allow a few related females to populate hundreds of kilometres of coastline and may explain their substantially larger temporal genetic variance but lower spatial genetic variance relative to the direct-developing species.

  3. A Case of Expansion of Traumatic Choroidal Rupture with Delayed-Developed Outer Retinal Changes

    Directory of Open Access Journals (Sweden)

    Kun Moon

    2013-08-01

    Full Text Available Background: This study aims to report the expansion of a choroidal rupture site caused by blunt ocular trauma using scanning laser ophthalmoscope-optical coherence tomography. Case Report: The clinical course of a 15-year-old girl with a traumatic ocular injury after being hit in the eye by an elbow was evaluated. Upon the first examination, the best-corrected visual acuity was 16/20. The findings were subretinal pigment epithelial hemorrhage and vertical choroidal rupture. Three weeks after the trauma, the patient's visual acuity was reduced to counting fingers at 30 cm. On fundus examination and fluorescein angiography subretinal pigment epithelial hemorrhage decreased, while the choroidal rupture expanded; on optical coherence tomography outer retinal changes in the adjacent area were detected. Discussion: This study reveals that the delayed expansion of a choroidal rupture site and the delayed change of the adjacent outer retina improved.

  4. Larval Survivorship and Settlement of Crown-of-Thorns Starfish (Acanthaster cf. solaris at Varying Algal Cell Densities

    Directory of Open Access Journals (Sweden)

    Morgan S. Pratchett

    2017-01-01

    Full Text Available The dispersal potential of crown-of-thorns starfish (CoTS larvae is important in understanding both the initiation and spread of population outbreaks, and is fundamentally dependent upon how long larvae can persist while still retaining the capacity to settle. This study quantified variation in larval survivorship and settlement rates for CoTS maintained at three different densities of a single-celled flagellate phytoplankton, Proteomonas sulcata (1 × 103, 1 × 104, and 1 × 105 cells/mL. Based on the larval starvation hypothesis, we expected that low to moderate levels of phytoplankton prey would significantly constrain both survival and settlement. CoTS larvae were successfully maintained for up to 50 days post-fertilization, but larval survival differed significantly between treatments. Survival was greatest at intermediate food levels (1 × 104 cells/mL, and lowest at high (1 × 105 cells/mL food levels. Rates of settlement were also highest at intermediate food levels and peaked at 22 days post-fertilization. Peak settlement was delayed at low food levels, probably reflective of delayed development, but there was no evidence of accelerated development at high chlorophyll concentrations. CoTS larvae were recorded to settle 17–43 days post-fertilization, but under optimum conditions with intermediate algal cell densities, peak settlement occurred at 22 days post-fertilization. Natural fluctuations in nutrient concentrations and food availability may affect the number of CoTS that effectively settle, but seem unlikely to influence dispersal dynamics.

  5. Design and development of ankle-foot prosthesis with delayed release of plantarflexion

    Directory of Open Access Journals (Sweden)

    Michael Mitchell, MSc

    2013-05-01

    Full Text Available A computer-controlled mechanism that fits a standard ankle-foot prosthesis was designed to capture the absorbed energy in the ankle and delay its release until specific times in the gait cycle. This mechanism used a direct current motor to take up and hold the compression of a carbon-fiber ankle joint. Based on the timing of the contact forces between the foot and the ground, a microprocessor released the spring at preset times later in the gait cycle. This mechanism was added to a Talux prosthetic foot and was employed by a user of a conventional energy-storage ankle-foot prosthesis. His gait was recorded using a motion analysis system. Five settings: 0, 55, 65, 75, and 85 ms delay were tested on separate days, and the standard kinematic and kinetic gait data were recorded. The user reported some settings were more comfortable than others. When these preferences were tested with a randomized double-blind trial, the preferences were not consistent. A second user showed a preference for the 55 ms delay. The modifications to the device resulted in changes to the gait of the subjects, including increased cadence and kinematics of the unaffected joints and a longer, slower push from the ankle, which was noticed by both of the subjects.

  6. Design and development of ankle-foot prosthesis with delayed release of plantarflexion.

    Science.gov (United States)

    Mitchell, Michael; Craig, Katelynn; Kyberd, Peter; Biden, Edmund; Bush, Greg

    2013-01-01

    A computer-controlled mechanism that fits a standard ankle-foot prosthesis was designed to capture the absorbed energy in the ankle and delay its release until specific times in the gait cycle. This mechanism used a direct current motor to take up and hold the compression of a carbon-fiber ankle joint. Based on the timing of the contact forces between the foot and the ground, a microprocessor released the spring at preset times later in the gait cycle. This mechanism was added to a Talux prosthetic foot and was employed by a user of a conventional energy-storage ankle-foot prosthesis. His gait was recorded using a motion analysis system. Five settings: 0, 55, 65, 75, and 85 ms delay were tested on separate days, and the standard kinematic and kinetic gait data were recorded. The user reported some settings were more comfortable than others. When these preferences were tested with a randomized double-blind trial, the preferences were not consistent. A second user showed a preference for the 55 ms delay. The modifications to the device resulted in changes to the gait of the subjects, including increased cadence and kinematics of the unaffected joints and a longer, slower push from the ankle, which was noticed by both of the subjects.

  7. Subcutaneous fat accumulation in early infancy is more strongly associated with motor development and delay than muscle growth.

    Science.gov (United States)

    Kanazawa, H; Kawai, M; Niwa, F; Hasegawa, T; Iwanaga, K; Ohata, K; Tamaki, A; Heike, T

    2014-06-01

    Physical growth in neurologically healthy preterm infants affects motor development. This study investigated the separate relationships between muscle and fat in infancy and later motor development and physical growth. Muscle thickness and subcutaneous fat thickness of the anterior thigh were measured using ultrasound images obtained from neurologically healthy preterm infants at birth, 3, 6, 12 and 18 months' corrected age. We also obtained the Pediatric Evaluation of Disability Inventory and Alberta Infant Motor Scale scores at 18 months' corrected age to assess motor ability and motor delay. Thirty preterm infants completed the study protocol. There was a significant positive correlation between motor ability and increments in subcutaneous fat thickness during the first 3 and 6 months' corrected age (r = 0.48 and 0.40, p muscle thickness growth in any of the periods. A secondary, logistic regression analysis showed that increments in subcutaneous fat thickness during the first 3 months were a protective factor for motor delay. Subcutaneous fat accumulation in early infancy is more strongly associated with motor development and delay than muscle growth. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  8. Adaptive locomotor behavior in larval zebrafish.

    Science.gov (United States)

    Portugues, Ruben; Engert, Florian

    2011-01-01

    In this study we report that larval zebrafish display adaptive locomotor output that can be driven by unexpected visual feedback. We develop a new assay that addresses visuomotor integration in restrained larval zebrafish. The assay involves a closed-loop environment in which the visual feedback a larva receives depends on its own motor output in a way that resembles freely swimming conditions. The experimenter can control the gain of this closed feedback loop, so that following a given motor output the larva experiences more or less visual feedback depending on whether the gain is high or low. We show that increases and decreases in this gain setting result in adaptive changes in behavior that lead to a generalized decrease or increase of motor output, respectively. Our behavioral analysis shows that both the duration and tail beat frequency of individual swim bouts can be modified, as well as the frequency with which bouts are elicited. These changes can be implemented rapidly, following an exposure to a new gain of just 175 ms. In addition, modifications in some behavioral parameters accumulate over tens of seconds and effects last for at least 30 s from trial to trial. These results suggest that larvae establish an internal representation of the visual feedback expected from a given motor output and that the behavioral modifications are driven by an error signal that arises from the discrepancy between this expectation and the actual visual feedback. The assay we develop presents a unique possibility for studying visuomotor integration using imaging techniques available in the larval zebrafish.

  9. Effects of music therapy in the treatment of children with delayed speech development - results of a pilot study

    Science.gov (United States)

    2010-01-01

    Background Language development is one of the most significant processes of early childhood development. Children with delayed speech development are more at risk of acquiring other cognitive, social-emotional, and school-related problems. Music therapy appears to facilitate speech development in children, even within a short period of time. The aim of this pilot study is to explore the effects of music therapy in children with delayed speech development. Methods A total of 18 children aged 3.5 to 6 years with delayed speech development took part in this observational study in which music therapy and no treatment were compared to demonstrate effectiveness. Individual music therapy was provided on an outpatient basis. An ABAB reversal design with alternations between music therapy and no treatment with an interval of approximately eight weeks between the blocks was chosen. Before and after each study period, a speech development test, a non-verbal intelligence test for children, and music therapy assessment scales were used to evaluate the speech development of the children. Results Compared to the baseline, we found a positive development in the study group after receiving music therapy. Both phonological capacity and the children's understanding of speech increased under treatment, as well as their cognitive structures, action patterns, and level of intelligence. Throughout the study period, developmental age converged with their biological age. Ratings according to the Nordoff-Robbins scales showed clinically significant changes in the children, namely in the areas of client-therapist relationship and communication. Conclusions This study suggests that music therapy may have a measurable effect on the speech development of children through the treatment's interactions with fundamental aspects of speech development, including the ability to form and maintain relationships and prosodic abilities. Thus, music therapy may provide a basic and supportive therapy for

  10. Effects of music therapy in the treatment of children with delayed speech development - results of a pilot study

    Directory of Open Access Journals (Sweden)

    Linden Ulrike

    2010-07-01

    Full Text Available Abstract Background Language development is one of the most significant processes of early childhood development. Children with delayed speech development are more at risk of acquiring other cognitive, social-emotional, and school-related problems. Music therapy appears to facilitate speech development in children, even within a short period of time. The aim of this pilot study is to explore the effects of music therapy in children with delayed speech development. Methods A total of 18 children aged 3.5 to 6 years with delayed speech development took part in this observational study in which music therapy and no treatment were compared to demonstrate effectiveness. Individual music therapy was provided on an outpatient basis. An ABAB reversal design with alternations between music therapy and no treatment with an interval of approximately eight weeks between the blocks was chosen. Before and after each study period, a speech development test, a non-verbal intelligence test for children, and music therapy assessment scales were used to evaluate the speech development of the children. Results Compared to the baseline, we found a positive development in the study group after receiving music therapy. Both phonological capacity and the children's understanding of speech increased under treatment, as well as their cognitive structures, action patterns, and level of intelligence. Throughout the study period, developmental age converged with their biological age. Ratings according to the Nordoff-Robbins scales showed clinically significant changes in the children, namely in the areas of client-therapist relationship and communication. Conclusions This study suggests that music therapy may have a measurable effect on the speech development of children through the treatment's interactions with fundamental aspects of speech development, including the ability to form and maintain relationships and prosodic abilities. Thus, music therapy may provide a basic

  11. Match/mismatch between the Mytilus edulis larval supply and seston quality: effect on recruitment.

    Science.gov (United States)

    Toupoint, Nicolas; Gilmore-Solomon, Lisandre; Bourque, François; Myrand, Bruno; Pernet, Fabrice; Olivier, Frédéric; Tremblay, Réjean

    2012-08-01

    We considered Cushing's match/mismatch theory in a heterotrophic environment and hypothesized that settlement and recruitment success in blue mussel are higher when the food supply is rich in polyunsaturated and essential fatty acids (PUFA/EFA). To test this hypothesis, we monitored larval development as well as fatty acid composition in trophic resources during two successive reproductive seasons. The decoupling we found between the presence of competent larvae in the water column and settlement rates strongly suggests that metamorphosis is delayed until conditions are suitable. In both years, the major mussel settlement peak was synchronized with a phytoplanktonic pulse rich in EFA, consisting of a large autotrophic bloom in 2007 and a short but substantial peak of picoeukaryotes in 2008. These results suggest a "trophic settlement trigger" that indirectly affects recruitment by strongly improving the settlement rate. Despite similar larval settlement rates during both years, the lower 2007 recruitment likely resulted from a mismatch with a high lipid-quality trophic resource. The seasonal trophic conditions differed greatly between the two years, with fatty acids profiles reflecting heterotrophic plankton production in 2007 and mostly autotrophic production in 2008. In agreement with Cushing's theory, our results highlight a match/mismatch, related to the food lipid quality rather than food quantity. For the first time, we show that the recruitment in marine bivalves may be dependent on phytoplanktonic pulses characterized by high levels of PUFA.

  12. Location Isn't Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment.

    Science.gov (United States)

    Donahue, Megan J; Karnauskas, Mandy; Toews, Carl; Paris, Claire B

    2015-01-01

    Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward.

  13. Location Isn't Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment.

    Directory of Open Access Journals (Sweden)

    Megan J Donahue

    Full Text Available Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward.

  14. Utilization of larval and pupal detritus by Aedes aegypti and Aedes albopictus.

    Science.gov (United States)

    Bara, J J; Clark, T M; Remold, S K

    2014-06-01

    The utilization of detritus sources by mosquito larvae during development may significantly affect adult life history traits and mosquito population growth. Many studies have shown invertebrate carcasses to be an important detritus source in larval habitats, but little is known regarding how invertebrate carcasses are utilized by mosquito larvae. We conducted two studies to investigate the rate of detritus consumption and its effect on larval development and life history traits. Overall, we found that Aedes aegypti and Aedes albopictus larvae rapidly consumed larval detritus, while pupal detritus was consumed at a significantly slower rate. We also found that the consumption of larval detritus significantly increased larval survivorship and decreased male development time but did not significantly influence female development time or pupal cephalothorax length for either sex. Our results suggest that the direct consumption of larval detritus can support the production of adults in larval habitats that lack allochthonous detritus inputs or where such organic inputs are insufficient. These studies indicate that different forms of invertebrate detritus are utilized in distinct ways by mosquito larvae, and therefore different forms of invertebrate detritus may have distinct effects on larval development and adult life history traits. © 2014 The Society for Vector Ecology.

  15. Fragile X syndrome and an isodicentric X chromosome in a woman with multiple anomalies, developmental delay, and normal pubertal development.

    Science.gov (United States)

    Freedenberg, D L; Gane, L W; Richards, C S; Lampe, M; Hills, J; O'Connor, R; Manchester, D; Taylor, A; Tassone, F; Hulseberg, D; Hagerman, R J; Patil, S R

    1999-07-30

    We report on an individual with developmental delays, short stature, skeletal abnormalities, normal pubertal development, expansion of the fragile X triplet repeat, as well as an isodicentric X chromosome. S is a 19-year-old woman who presented for evaluation of developmental delay. Pregnancy was complicated by a threatened miscarriage. She was a healthy child with intellectual impairment noted in infancy. Although she had global delays, speech was noted to be disproportionately delayed with few words until age 3.5 years. Facial appearance was consistent with fragile X syndrome. Age of onset of menses was 11 years with normal breast development. A maternal male second cousin had been identified with fragile X syndrome based on DNA studies. The mother of this child (S's maternal first cousin) and the grandfather (S's maternal uncle) were both intellectually normal but were identified as carrying triplet expansions in the premutation range. S's mother had some school difficulties but was not identified as having global delays. Molecular analysis of S's fragile X alleles noted an expansion of more than 400 CGG repeats in one allele. Routine cytogenetic studies of peripheral blood noted the presence of an isodicentric X in 81of 86 cells scored. Five of 86 cells were noted to be 45,X. Cytogenetic fra(X) studies from peripheral blood showed that the structurally normal chromosome had the fragile site in approximately 16% of the cells. Analysis of maternal fragile X alleles identified an allele with an expansion to approximately 110 repeats. FMRP studies detected the expression of the protein in 24% of cells studied. To our knowledge, this is the first patient reported with an isodicentric X and fragile X syndrome. Whereas her clinical phenotype is suggestive of fragile X syndrome, her skeletal abnormalities may represent the presence of the isodicentric X. Treatment of S with 20 mg/day of Prozac improved her behavior. In the climate of cost con trol, this individual

  16. Adaptation to divergent larval diets in the medfly, Ceratitis capitata.

    Science.gov (United States)

    Leftwich, Philip T; Nash, William J; Friend, Lucy A; Chapman, Tracey

    2017-02-01

    Variation in diet can influence the timing of major life-history events and can drive population diversification and ultimately speciation. Proximate responses of life histories to diet have been well studied. However, there are scant experimental data on how organisms adapt to divergent diets over the longer term. We focused on this omission by testing the responses of a global pest, the Mediterranean fruitfly, to divergent selection on larval diets of different nutritional profiles. Tests conducted before and after 30 generations of nutritional selection revealed a complex interplay between the effects of novel larval dietary conditions on both plastic and evolved responses. There were proximate-only responses to the larval diet in adult male courtship and the frequency of copulation. Males on higher calorie larval diets consistently engaged in more bouts of energetic courtship. In contrast, following selection, larval development time, and egg to adult survival showed evidence of evolved divergence between diet regimes. Adult body size showed evidence for adaptation, with flies being significantly heavier when reared on their "own" diet. The results show the multifaceted responses of individuals to dietary selection and are important in understanding the extreme generalism exhibited by the medfly.

  17. Development of a novel mouse model of amodiaquine-induced liver injury with a delayed onset.

    Science.gov (United States)

    Metushi, Imir G; Cai, Ping; Dervovic, Dzana; Liu, Feng; Lobach, Alexandra; Nakagawa, Tetsuya; Uetrecht, Jack

    2015-01-01

    Amodiaquine (AQ) treatment is associated with a high incidence of idiosyncratic drug-induced liver injury (IDILI) and agranulocytosis. Evidence suggests that AQ-induced IDILI is immune mediated. A significant impediment to mechanistic studies of IDILI is the lack of valid animal models. This study reports the first animal model of IDILI with characteristics similar to mild IDILI in humans. Treatment of female C57BL/6 mice with AQ led to liver injury with delayed onset, which resolved despite continued treatment. Covalent binding of AQ was detected in the liver, which was greater in female than in male mice, and higher in the liver than in other organs. Covalent binding in the liver was maximal by Day 3, which did not explain the delayed onset of alanine aminotransferase (ALT) elevation. However, coincident with the elevated serum ALT, infiltration of liver and splenic mononuclear cells and activation of CD8 T-cells within the liver were identified. By Week 7, when ALT levels had returned close to normal, down-regulation of several inflammatory cytokines and up-regulation of PD-1 on T-cells suggested induction of immune tolerance. Treatment of Rag1(-/-) mice with AQ resulted in higher ALT activities than C57BL/6 mice, which suggested that the adaptive immune response was responsible for immune tolerance. In contrast, depletion of NK cells significantly attenuated the increase in ALT, which implied a role for NK cells in mild AQ-induced IDILI. This is the first example of a delayed-onset animal model of IDILI that appears to be immune-mediated.

  18. Development of the Larval Amphibian Growth and Development Assay: effects of chronic 4-tert-octylphenol or 17β-trenbolone exposure in Xenopus laevis from embryo to juvenile.

    Science.gov (United States)

    Haselman, Jonathan T; Kosian, Patricia A; Korte, Joseph J; Olmstead, Allen W; Iguchi, Taisen; Johnson, Rodney D; Degitz, Sigmund J

    2016-12-01

    The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized test guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan's Ministry of the Environment. The LAGDA was designed to evaluate apical effects of chronic chemical exposure on growth, thyroid-mediated amphibian metamorphosis and reproductive development. During the validation phase, two well-characterized endocrine-disrupting chemicals were tested to evaluate the performance of the initial assay design: xenoestrogen 4-tert-octylphenol (tOP) and xenoandrogen 17β-trenbolone (TB). Xenopus laevis embryos were exposed, in flow-through conditions, to tOP (nominal concentrations: 0.0, 6.25, 12.5, 25 and 50 µg l(-1) ) or TB (nominal concentrations: 0.0, 12.5, 25, 50 and 100 ng l(-1) ) until 8 weeks post-metamorphosis, at which time growth measurements were taken, and histopathology assessments were made of the gonads, reproductive ducts, liver and kidneys. There were no effects on growth in either study and no signs of overt toxicity, sex reversal or gonad dysgenesis. Exposure to tOP caused a treatment-related decrease in circulating thyroxine and an increase in thyroid follicular cell hypertrophy and hyperplasia (25 and 50 µg l(-1) ) during metamorphosis. Müllerian duct development was affected after exposure to both chemicals; tOP exposure caused dose-dependent maturation of oviducts in both male and female frogs, whereas TB exposure caused accelerated Müllerian duct regression in males and complete regression in >50% of the females in the 100 ng l(-1) treatment. Based on these results, the LAGDA performed adequately to evaluate apical effects of chronic exposure to two endocrine-active compounds and is the first standardized amphibian multiple life stage toxicity test to date. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  19. Delay-Tolerant Networking for Space Flight Operations: Design and Development

    Science.gov (United States)

    Burleigh, Scott

    2008-01-01

    Large-scale future space exploration will offer complex communication challenges that may be best addressed by establishing a network infrastructure. The Internet protocols are not well suited for operation of a network over interplanetary distances; a Delay-Tolerant Networking (DTN) architecture has been proposed instead. DTN is now a rapidly growing research field, but most implementations are mainly aimed at supporting applications of DTN technology to terrestrial networking problems. Those implementations are not necessarily suitable for deployment in an interplanetary network. Interplanetary Overlay Network (ION) is an implementation of the DTN architecture that is specifically designed for use in resource-constrained embedded systems, such as interplanetary robotic spacecraft.

  20. Delayed development of neural language organization in very preterm born children.

    Science.gov (United States)

    Mürner-Lavanchy, Ines; Steinlin, Maja; Kiefer, Claus; Weisstanner, Christian; Ritter, Barbara Catherine; Perrig, Walter; Everts, Regula

    2014-01-01

    This study investigates neural language organization in very preterm born children compared to control children and examines the relationship between language organization, age, and language performance. Fifty-six preterms and 38 controls (7-12 y) completed a functional magnetic resonance imaging language task. Lateralization and signal change were computed for language-relevant brain regions. Younger preterms showed a bilateral language network whereas older preterms revealed left-sided language organization. No age-related differences in language organization were observed in controls. Results indicate that preterms maintain atypical bilateral language organization longer than term born controls. This might reflect a delay of neural language organization due to very premature birth.

  1. [Delay and cessation of aging processes by manipulation of reproduction, food intake and development in insects].

    Science.gov (United States)

    Collatz, K-G

    2004-06-01

    Insects can serve as excellent models to show that the genetically determined life span of organisms as well as that of other traits is characterized by high phenotypic plasticity. Depending on different environmental conditions the life cycle strategy can therefore be highly variable. Thus developmental and aging processes are subjected to delaying or accelerating influences or can even be interrupted. Availability of protein to fulfill reproductive requirements, intermittent starvation, and the photoperiodic induction of reproductive diapause were taken as examples for the study of selected abiotic factors which influence the life history of the blowfly Phormia terraenovae and the beetle Gastroidea viridula.

  2. Preliminary development of flaw evaluation procedures for delayed hydride cracking initiation under hydride non-ratcheting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S.; Cui, J.; Kawa, D.; Shek, G.K.; Scarth, D.A. [Kinectrics Inc., Toronto, Ontario (Canada)

    2006-07-01

    The flaw evaluation procedure for Delayed Hydride Cracking (DHC) initiation currently provided in the CSA Standard N285.8 was developed for hydride ratcheting conditions, in which flaw-tip hydrides do not completely dissolve at peak temperature. Test results have shown that hydrided regions formed under non-ratcheting conditions, in which flaw-tip hydrides completely dissolve at peak temperature, have significantly higher resistance to cracking than those formed under ratcheting conditions. This paper presents some preliminary work on the development of a procedure for the evaluation of DHC initiation for flaws under hydride non-ratcheting conditions. (author)

  3. 'Peer pressure' in larval Drosophila?

    Science.gov (United States)

    Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

    2014-06-06

    Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on 'peer pressure', that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila.

  4. Proteomic Analysis of Larval Midgut from the Silkworm (Bombyx mori

    Directory of Open Access Journals (Sweden)

    Sai Zhang

    2011-01-01

    Full Text Available The midgut is the major organ for food digestion, nutrient absorption and also a barrier for foreign substance. The 5th-instar larval stage of silkworm is very important for larval growth, development, and silk production. In the present study, we used 2-DE and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS to analyze the midgut proteins from the 5th-instar larvae as well as the midgut proteins under starvation condition. A total of 96 proteins were identified in this study; and among them, 69 proteins were observed in midgut for the first time. We also found that the silkworm larval midgut responded to starvation by producing a 10 kDa heat shock protein and a diapause hormone precursor.

  5. Biological Strategies of Dermestes maculatus DeGeer (Coleoptera: Dermestidae) at Larval Stages in Different Temperatures.

    Science.gov (United States)

    Zanetti, N I; Visciarelli, E C; Centeno, N D

    2016-12-01

    The intraspecific variation in larval instars is a widely distributed phenomenon amongst holometabolous insects. Several factors can affect the number of instars, such as temperature, humidity, and density. Only a few references could be found in the literature because the invariability in the number of larval instars is considered normal, and the issue has raised little to no interest. Despite this, no study to date has intended to assess or focus on the larval development. Here, we analyzed the effect of different rearing temperature on the larval stage of Dermestes maculatus DeGeer (Coleoptera: Dermestidae). The results indicated that at all temperatures, L5 represented a decisive point for individuals as well as the other later larval instars, because the next step to follow was to pupate or molt to the next larval instar. Furthermore, there were mainly two populations, L5 and L6, although in different proportions according to temperature. We also found that at a greater number of instars, the larval development at all temperatures lasted longer. Moreover, the exponential model was the best adjustment in the developmental time of all populations as well as for the accumulated developmental time of L1-L4. Thus, we conclude that random factors such as genetics could probably cause interspecific variability in D. maculatus larval development.

  6. DELAYED FLOWERING, an Arabidopsis Gene That Acts in the Autonomous Flowering Promotion Pathway and Is Required for Normal Development

    Institute of Scientific and Technical Information of China (English)

    Ming-Jie Chen; Zheng Yuan; Hai Huang

    2006-01-01

    The control of flowering time in higher plants is one of the most important physiological processes and is critical for their reproductive success. To investigate the mechanisms controlling flowering time, we screened for Arabidopsis mutants with late-flowering phenotypes. One mutant, designated delayed flowering (dfr) in the Landsberg erecta (Ler) ecotype, was identified with delayed flowering time. Genetic analysis revealed that dfr is a single gene recessive nuclear mutant and the mutation was mapped to a locus tightly linked to UFO on chromosome 1. To our knowledge, no gene regulating flowering time has been reported yet in this region. The dfr mutant plant showed a delayed flowering time under the different growth conditions examined,including long- and short-day photoperiods and gibberellic acid GA3 treatments, suggesting that DFR is a gene involved in the autonomous flowering promotion pathway. The Arabidopsis gene FLOWERING LOCUS C (FLC) plays a central role in repressing flowering and its transcripts are undetectable in wild-type Ler.However, FLCexpression was upregulated in the dfrmutant, suggesting that DFR is a negative regulator of FLC. In addition, the dfr mutant plant displayed altered valve shapes of the silique and the number of trichomes and branches of each trichome were both reduced, indicating that the DRFgene is also required for normal plant development. Moreover, dfr leafy-5 (Ify-5) double mutant plants showed a much later flowering time than either dfr or Ify-5 single mutants, indicating that DFR and LFYact synergistically to promote flowering in Arabidopsis.

  7. Deficiency of inducible and endothelial nitric oxide synthase results in diminished bone formation and delayed union and nonunion development.

    Science.gov (United States)

    Meesters, D M; Neubert, S; Wijnands, K A P; Heyer, F L; Zeiter, S; Ito, K; Brink, P R G; Poeze, M

    2016-02-01

    Between 5% and 10% of all fractures fail to heal adequately resulting in nonunion of the fracture fragments. This can significantly decrease a patient's quality of life and create associated psychosocial and socio-economic problems. Nitric oxide (NO) and nitric oxide synthases (NOS) have been found to be involved in fracture healing, but until now it is not known if disturbances in these mechanisms play a role in nonunion and delayed union development. In this study, we explored the role of endothelial and inducible NOS deficiency in a delayed union model in mice. A 0.45mm femur osteotomy with periosteal cauterization followed by plate-screw osteosynthesis was performed in the left leg of 20-24week old wild type, Nos2(-/-) and Nos3(-/-) mice. Contralateral unfractured legs were used as a control. Callus volume was measured using micro-computed tomography (μCT) after 28 and 42days of fracture healing. Immuno histochemical myeloperoxidase (MPO) staining was performed on paraffin embedded sections to assess neutrophil influx in callus tissue and surrounding proximal and distal marrow cavities of the femur. After 7 and 28days of fracture healing, femurs were collected for amino acid and RNA analysis to study arginine-NO metabolism. With μCT, delayed union was observed in wild type animals, whereas in both Nos2(-/-) and Nos3(-/-) mice nonunion development was evident. Both knock-out strains also showed a significantly increased influx of MPO when compared with wild type mice. Concentrations of amino acids and expression of enzymes related to the arginine-NO metabolism were aberrant in NOS deficient mice when compared to contralateral control femurs and wild type samples. In the present study we show for the first time that the absence of nitric oxide synthases results in a disturbed arginine-NO metabolism and inadequate fracture healing with the transition of delayed union into a nonunion in mice after a femur osteotomy. Based on these data we suggest that the

  8. Choline supplementation mitigates trace, but not delay, eyeblink conditioning deficits in rats exposed to alcohol during development.

    Science.gov (United States)

    Thomas, Jennifer D; Tran, Tuan D

    2012-03-01

    Children exposed to alcohol prenatally suffer from a range of physical, neuropathological, and behavioral alterations, referred to as fetal alcohol spectrum disorders (FASD). Both the cerebellum and hippocampus are affected by alcohol exposure during development, which may contribute to behavioral and cognitive deficits observed in children with FASD. Despite the known neuropathology associated with prenatal alcohol exposure, many pregnant women continue to drink (heavy drinkers, in particular), creating a need to identify effective treatments for their children who are adversely affected by alcohol. We previously reported that choline supplementation can mitigate alcohol's effects on cognitive development, specifically on tasks which depend on the functional integrity of the hippocampus. The present study examined whether choline supplementation could differentially mitigate alcohol's effects on trace eyeblink classical conditioning (ECC, a hippocampal-dependent task) and delay ECC (a cerebellar-dependent task). Long-Evans rats were exposed to 5.25 g/kg/day alcohol via gastric intubation from postnatal days (PD) 4-9, a period of brain development equivalent to late gestation in humans. A sham-intubated control group was included. From PD 10-30, subjects received subcutaneous injections of 100 mg/kg choline chloride or vehicle. Beginning on PD 32-34, subjects were trained on either delay or trace eyeblink conditioning. Performance of subjects exposed to alcohol was significantly impaired on both tasks, as indicated by significant reductions in percentage and amplitude of conditioned eyeblink responses, an effect that was attenuated by choline supplementation on the trace, but not delay conditioning task. Indeed, alcohol-exposed subjects treated with choline performed at control levels on the trace eyeblink conditioning task. There were no significant main or interactive effects of sex. These data indicate that choline supplementation can significantly reduce the

  9. Larval Myogenesis in the Articulate Brachiopod Argyrotheca cordata (Risso, 1826)

    DEFF Research Database (Denmark)

    Altenburger, Andreas; Wanninger, Andreas Wilhelm Georg

    2008-01-01

    and micromorphological data to this debate, we investigated muscle formation in larvae of the brooding articulate brachiopod Argyrotheca cordata using immunocytochemistry combined with confocal laser scanning microscopy. Full grown larvae are three-lobed and show two pairs of bristle bundles. During larval development...

  10. A staging system for larval cod (Gadus morhua L.)

    OpenAIRE

    1986-01-01

    A staging system of larval cod is described. The system is based on the resorption of the yolk mass and the cell layers surrounding it combined with eye, mouth and gut development. A determination key is given. Each stage is described in detail.

  11. Characterization of anopheline (Diptera: Culicidae) larval habitats in Nouakchott, Mauritania.

    Science.gov (United States)

    Salem, O Ahmedou Salem Mohamed; Khadijetou, M Lekweiry; Moina, M Hasni; Lassana, Konate; Sébastien, Briolant; Ousmane, Faye; Ali, O Mohamed Salem Boukhary

    2013-12-01

    Despite the increasing number of reported autochthonous malaria cases in Nouakchott and the identification of Anopheles arabiensis as the major malaria vector in this Saharan city, anopheline larval habitats have never been identified so far. The objective of this study was to identify and characterize anopheline larval habitats in Nouakchott. During September and October 2012, samples from pools of rainwater, water discharged from standpipes and household drinking water tanks in the districts of Dar Naim, Teyarett and Arafat were analyzed for the presence/absence of anopheline larvae and physicochemical characterization of breeding habitats. Of the 51 prospected water bodies, eight consisting of seven water discharged from standpipes and one household drinking water tank were productive for Anopheles sp. All emerged anopheline mosquitoes from the positive dipping were morphologically identified as members of the An. gambiae complex. Multivariate regression analyses showed that a salinity up to 0.1 g/l and a shaded situation were respectively protective factors against high larval density in breeding sites (adjusted odds ratio = 0.62, 95% CI [0.44-0.87], p = 0.0052 and adjusted odds ratio = 0.56, 95% CI [0.44-0.71, p <0.0001] and a pH up to 7.61 was a risk factor for high larval density in breeding sites (adjusted odds ratio = 1.56, 95% CI [1.25-1.95], p = 0.0001). The study demonstrated in Nouakchott that despite an arid and dry climate, human practices have contributed to the establishment of favourable environmental conditions for the development of anopheline mosquitoes and, therefore, maintaining malaria transmission in this Saharan city. The core malaria vector control intervention as the use of long-lasting insecicidal nets (LLINs) could be complemented in Nouakchott by larval source control. In this area, appropriate larval control measures may be recommended in line with an integrated vector management (IVM) approach.

  12. Characterization of anopheline (Diptera: Culicidae larval habitats in Nouakchott, Mauritania

    Directory of Open Access Journals (Sweden)

    O. Ahmedou Salem Mohamed Salem

    2013-12-01

    Full Text Available Background & objectives: Despite the increasing number of reported autochthonous malaria cases in Nouakchott and the identification of Anopheles arabiensis as the major malaria vector in this Saharan city, anopheline larval habitats have never been identified so far. The objective of this study was to identify and characterize anopheline larval habitats in Nouakchott. Methods: During September and October 2012, samples from pools of rainwater, water discharged from standpipes and household drinking water tanks in the districts of Dar Naim, Teyarett and Arafat were analyzed for the presence/absence of anopheline larvae and physicochemical characterization of breeding habitats. Results: Of the 51 prospected water bodies, eight consisting of seven water discharged from standpipes and one household drinking water tank were productive for Anopheles sp. All emerged anopheline mosquitoes from the positive dipping were morphologically identified as members of the An. gambiae complex. Multivariate regression analyses showed that a salinity up to 0.1 g/l and a shaded situation were respectively protective factors against high larval density in breeding sites (adjusted odds ratio = 0.62, 95% CI [0.44-0.87], p = 0.0052 and adjusted odds ratio = 0.56, 95% CI [0.44-0.71, p <0.0001] and a pH up to 7.61 was a risk factor for high larval density in breeding sites (adjusted odds ratio = 1.56, 95% CI [1.25-1.95], p = 0.0001. Interpretation & conclusion: The study demonstrated in Nouakchott that despite an arid and dry climate, human practices have contributed to the establishment of favourable environmental conditions for the development of anopheline mosquitoes and, therefore, maintaining malaria transmission in this Saharan city. The core malaria vector control intervention as the use of long-lasting insecicidal nets (LLINs could be complemented in Nouakchott by larval source control. In this area, appropriate larval control measures may be recommended in line

  13. 卵形鲳鲹胚后发育阶段鳃的分化和发育%Differentiation and development of the gill in Trachinotus ovatus during larval and juvenile development

    Institute of Scientific and Technical Information of China (English)

    区又君; 何永亮; 李加儿

    2012-01-01

    We documented the differentiation and development of the gill and the relationship between gill structure and function in Trachinotus ovatus using histology and scanning electron microscopy. Development of the gill was divided into three stages in the larvae and juveniles. Stage I included organ-primordium formation between 0-3 days after hatching (DAH). During this stage, gill-primordia were present but undifferentiated, there were no gill rakers, and respiration occurred primarily via the finfold, skin, and the microvascular surface of the yolk-sac. Stage II occurred between 4-17 DAH and was characterized by differentiation and development of gill filaments. Gill arches, filaments, secondary gill lamella, and gill rakers developed gradually and the basic structure and morphology of the gill were established. Stage III was initiated at 18 DAH, at which time the gill organs (e.g., arches, filaments, secondary gill lamella, and rakers) resembled the adult in terms of morphology and function. The total number of gill filaments increased with the increasing body weight and body length in larvae and juveniles. Thus, the single secondary gill lamella area and total respiratory area also increased with an increase of body weight. The differentiation and development of the gill was in accordance with growth, development, and function in larval and juvenile T. Ovatus.%采用组织学和扫描电镜等方法,研究了卵形鲳鲹(Trachinotus ovatus)胚后发育阶段鳃的分化和发育及其结构和功能的关系.观察发现,仔稚鱼鳃的早期发育可分为3个阶段:第1阶段(0~3日龄)为原基期,鳃原基形成但未分化,鳃耙未出现,仔鱼主要依靠鳍褶、皮肤和卵黄囊上的微血管进行呼吸;第2阶段(4~17日龄)为鳃丝分化、发育期,鳃弓、鳃丝、鳃小片、鳃耙逐渐形成,具备鳃的基本结构和形态特点;第3阶段(18日龄之后)为鳃器官生长发育完善期,鳃弓、鳃丝、鳃小片、鳃耙发育完

  14. Histological Studies on the Development of Digestive System In Larval and Juvenile Starry Flounder%星斑川鲽仔稚鱼消化系统发育的组织学研究

    Institute of Scientific and Technical Information of China (English)

    方华华; 王波

    2011-01-01

    A histological examination was made on the development of digestive system in larval and juvenile starry flounder Platichtbys stellatus Pallas from 1 day to 35 days.In 3 days, the digestive tract in the larvae was formed but no food was intaken when the starry flounder was in endogenous nutrition.In 3-5 days , the mixotrophic stage which was the transition from endogenous nutrition to exogenous nutrition, the yolk was absorbed fairly well and disappeared, while the digestive tract was differentiated into six portions:buccopharynnx, oesophagus , stomach, anterior- middle intestine, posterior intestine and anus.The larval digestive system was morphologically ready to be absorbed to food at this time.Then, these digestive tract and associated glands became mature gradually with the development.Gastric glands were observed in 16 days ,which indicated it was a kind of fish with faster development.%使用石蜡切片技术对1~35日龄星斑川鲽的仔稚鱼消化系统进行组织学观察和研究.结果表明,星斑川鲽消化系统的发育主要分成3个阶段:从初孵到3日龄是卵黄阶段,其消化道为一细长的管道;从3日龄到5日龄是后卵黄阶段(混合营养阶段),卵黄被逐渐吸收,是卵黄阶段转向外源性营养阶段的过渡,消化道明显分化成口咽腔、食道、胃、前中肠、后肠和肛门,仔鱼消化系统具备了摄食和消化外源性食物的能力.此后,随着鱼体的生长,粘膜层的褶皱增加,消化道上皮细胞进一步分化,消化系统从功能和结构上逐步完善.16日龄,胃腺出现,标志着稚鱼期的开始,也表明星斑川鲽是一种发育较快的鱼类.

  15. Growth,development and adult fecundity of Chrysoperla carnea feeding on different larval diets%猎物对普通草蛉发育和繁殖能力的影响

    Institute of Scientific and Technical Information of China (English)

    麦麦提·亚生; 阿克旦·吾外士; 牙生·沙力; 刘建; 阿孜古丽·热依木; 丁瑞丰

    2015-01-01

    为探讨不同猎物对普通草蛉[Chrysoperla carnea (Stephens)]幼虫生长发育和成虫繁殖能力的影响,研究了普通草蛉幼虫取食棉蚜(Aphis gossypii Glover)、萝卜蚜[Lipaphis erysimi (Kaltenbach)]、榆长斑蚜[Tinocallis saltans (Nevsky)]、截形叶螨(Tetranychus truncatus Ehara)、枸杞木虱(Poratrioza sinica Yang & Li)和麦蛾[Si-totroga cerealella (Olivier)]卵共6种食物时的生长发育和成虫繁殖能力。结果表明:幼虫取食棉蚜发育历期最短,为(9.66±0.13)d、取食麦蛾卵发育历期最长,为(11.35±0.26)d;取食麦蛾卵时蛹期最短,为(7.33±0.16)d、取食萝卜蚜时蛹期最长,为(8.85±0.25)d;幼虫取食棉蚜死亡率最低,为(20.05±0.2)%、取食萝卜蚜时死亡率最高,为(31.25±0.52)%;幼虫取食截形叶螨不能完成幼虫期生长发育;幼虫取食棉蚜时蛹最重,为(8.27±0.20)mg,取食枸杞木虱时蛹最轻,为(7.28±0.18)mg;幼虫取食枸杞木虱时羽化率最低,为(69.29±0.79)%、取食萝卜蚜时羽化率最高,为(77.25±1.94)%;幼虫取食麦蛾卵时雌虫寿命最长,为(71.54±1.87)d、取食榆长斑蚜时雌虫寿命最短,为(57.35±3.66)d。幼虫取食不同食物对普通草蛉成虫产卵前期和产卵量无显著影响。幼虫食物是影响普通草蛉生长发育和繁殖能力的重要因素之一,普通草蛉幼虫取食棉蚜最适合其生长发育和繁殖。%In order to explore the influences of different larval diets on the growth and reproductive capacity of the lacewing Chrysoperla carnea (Stephens),the growth,development and adult fecundity of the lacewing C .car-nea were investigated by feeding the lacewing larvae with the cotton aphid Aphis gossypii Glover,Lipaphis erysimi (Kaltenbach),Tinocallis saltans (Nevsky),Tetranychus truncatus ,Poratrioza sinica Yang

  16. Undernutrition during the brain growth period of the rat significantly delays the development of processes mediating Pavlovian trace conditioning.

    Science.gov (United States)

    Rudy, J W; Castro, C A

    1990-05-01

    Pavlovian trace conditioning procedures allow one to assess the ability of animals to associate events that are temporally separated because the conditioned stimulus terminates prior to the occurrence of the unconditioned stimulus. We report that undernutrition during Postnatal Days 2-18 significantly delays the development of trace conditioning to a visual stimulus. Previously undernourished 20-day-old rats conditioned when no temporal interval separated the termination of the CS and US onset (0-s trace interval). However, it was not until the undernourished pups were 30 days old that they conditioned when the trace interval was 10 or 30 s. In contrast, control pups only 20 days old were able to condition when a 10-s trace interval separated the CS and US events, and 25-day-old control pups conditioned when the interval was either 10 or 30 s. These results suggest that undernutrition delays the development of processes that enable the rat to sustain a representation of a visual CS during the trace interval.

  17. Delayed Puberty

    DEFF Research Database (Denmark)

    Kolby, Nanna; Busch, Alexander Siegfried; Juul, Anders

    2017-01-01

    Delayed puberty can be a source of great concern and anxiety, although it usually is caused by a self-limiting variant of the normal physiological timing named constitutional delay of growth and puberty (CDGP). Delayed puberty can, however, also be the first presentation of a permanent condition ...... mineral density) and psychological (e.g., low self-esteem) and underline the importance of careful clinical assessment of the patients.......Delayed puberty can be a source of great concern and anxiety, although it usually is caused by a self-limiting variant of the normal physiological timing named constitutional delay of growth and puberty (CDGP). Delayed puberty can, however, also be the first presentation of a permanent condition...

  18. Risk Factors and Relationship Between Intestinal Parasites and the Growth Retardation and Psychomotor Development Delays of Children in Şanlıurfa, Turkey.

    Science.gov (United States)

    Yentur Doni, Nebiye; Yildiz Zeyrek, Fadile; Simsek, Zeynep; Gurses, Gulcan; Sahin, İbrahim

    2015-12-01

    The objective of this study was to determine the risk factors for and relationship among parasitic infections, growth retardation, and psychomotor developmental delays in children aged 6 years and below. This case-control study was performed in Şanlıurfa in southeastern Turkey between October and December 2007. Data were collected using a structured questionnaire, anthropometry, Ankara Development Screening Inventory, and laboratory analysis of stool specimens. The most common parasite was Giardia intestinalis (42.53%) followed by Enterobius vermicularis (27.58%), Ascaris lumbricoides (18.39%), Hymenolepis nana (5.75%), Trichuris trichiura (3.45%), Escherichia coli (1.15%), and Blastocystis spp. (1.15%). Fifty-eight percent of all children were infected with intestinal parasites; 55.2% had only one parasite, whereas 44.8% had multiple parasites. The children infected with G. intestinalis and other intestinal parasites had significantly higher levels of growth retardation and psychomotor development delay than non-infected children. Children with parasitic infections had growth delay up to 2.9 times, general development delay up to 1.9 times, language-cognitive development delay up to 2.2 times, and fine motor development delay up to 2.9 times higher than children without any parasitic infections. However, no significant relationship among intestinal parasites, gross motor development, social-self skills, and development delay was identified. The education level of parents, poor economic situation, number of households, not washing hands, playing with soil, family history of parasitic infection were the significant risk factors for intestinal parasites. Our study indicates that the presence of either malnutrition or intestinal parasites may put a child in a high-risk group for developmental delays and growth retardation. Therefore, public health interventions can embrace nationwide deworming in children.

  19. Environmental factors limiting fertilisation and larval success in corals

    Science.gov (United States)

    Woods, Rachael M.; Baird, Andrew H.; Mizerek, Toni L.; Madin, Joshua S.

    2016-12-01

    Events in the early life history of reef-building corals, including fertilisation and larval survival, are susceptible to changes in the chemical and physical properties of sea water. Quantifying how changes in water quality affect these events is therefore important for understanding and predicting population establishment in novel and changing environments. A review of the literature identified that levels of salinity, temperature, pH, suspended sediment, nutrients and heavy metals affect coral early life-history stages to various degrees. In this study, we combined published experimental data to determine the relative importance of sea water properties for coral fertilisation success and larval survivorship. Of the water properties manipulated in experiments, fertilisation success was most sensitive to suspended sediment, copper, salinity, phosphate and ammonium. Larval survivorship was sensitive to copper, lead and salinity. A combined model was developed that estimated the joint probability of both fertilisation and larval survivorship in sea water with different chemical and physical properties. We demonstrated the combined model using water samples from Sydney and Lizard Island in Australia to estimate the likelihood of larvae surviving through both stages of development to settlement competency. Our combined model could be used to recommend targets for water quality in coastal waterways as well as to predict the potential for species to expand their geographical ranges in response to climate change.

  20. Delayed fission

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-07-01

    Delayed fission is a nuclear decay process that couples {beta} decay and fission. In the delayed fission process, a parent nucleus undergoes {beta} decay and thereby populates excited states in the daughter. If these states are of energies comparable to or greater than the fission barrier of the daughter, then fission may compete with other decay modes of the excited states in the daughter. In this paper, mechanism and some experiments of the delayed fission will be discussed. (author)

  1. [Canine peritoneal larval cestodosis caused by Mesocestoides spp. larval stages].

    Science.gov (United States)

    Häußler, T C; Peppler, C; Schmitz, S; Bauer, C; Hirzmann, J; Kramer, M

    2016-01-01

    In a female dog with unspecific clinical symptoms, sonography detected a hyperechoic mass in the middle abdomen and blood analysis a middle grade systemic inflammatory reaction. Laparotomy revealed a peritoneal larval cestodosis (PLC). The diagnosis of an infection with tetrathyridia of Mesocestoides spp. was confirmed by parasitological examination and molecularbiological analysis. Reduction of the intra-abdominal parasitic load as well as a high dose administration of fenbendazole over 3 months led to a successful treatment which could be documented sonographically and by decreased concentrations of C-reactive protein (CRP). Seven months after discontinuation of fenbendazole administration, PLC recurred, pre-empted by an elevation of serum CRP values. According to the literature a life-long fenbendazole treatment was initiated. In cases of unclear chronic granulomatous inflammations in the abdominal cavity in dogs, PLC should be considered. CRP concentration and sonographic examinations are suitable to control for treatment success and a possibly occurring relapse.

  2. Delay and impairment in brain development and function in rat offspring after maternal exposure to methylmercury

    NARCIS (Netherlands)

    Radonjic, M.; Cappaert, N.L.M.; Vries, E.F.J.; Esch, C.E.F.; Kuper, F.C.; van Waarde, A.; Dierckx, R.A.J.O.; Wadman, W.J.; Wolterbeek, A.P.M.; Stierum, R.H.; de Groot, D.M.G.

    2013-01-01

    Maternal exposure to the neurotoxin methylmercury (MeHg) has been shown to have adverse effects on neural development of the offspring in man. Little is known about the underlying mechanisms by which MeHg affects the developing brain. To explore the neurodevelopmental defects and the underlying

  3. Delay and Impairment in Brain Development and Function in Rat Offspring After Maternal Exposure to Methylmercury

    NARCIS (Netherlands)

    Radonjic, Marijana; Cappaert, Natalie L. M.; de Vries, Erik F. J.; de Esch, Celine E. F.; Kuper, Frieke C.; van Waarde, Aren; Dierckx, Rudi A. J. O.; Wadman, Wytse J.; Wolterbeek, Andre P. M.; Stierum, Rob H.; de Groot, Didima M. G.

    Maternal exposure to the neurotoxin methylmercury (MeHg) has been shown to have adverse effects on neural development of the offspring in man. Little is known about the underlying mechanisms by which MeHg affects the developing brain. To explore the neurodevelopmental defects and the underlying

  4. Larval and nurse worker control of developmental plasticity and the evolution of honey bee queen-worker dimorphism.

    Science.gov (United States)

    Linksvayer, T A; Kaftanoglu, O; Akyol, E; Blatch, S; Amdam, G V; Page, R E

    2011-09-01

    Social evolution in honey bees has produced strong queen-worker dimorphism for plastic traits that depend on larval nutrition. The honey bee developmental programme includes both larval components that determine plastic growth responses to larval nutrition and nurse components that regulate larval nutrition. We studied how these two components contribute to variation in worker and queen body size and ovary size for two pairs of honey bee lineages that show similar differences in worker body-ovary size allometry but have diverged over different evolutionary timescales. Our results indicate that the lineages have diverged for both nurse and larval developmental components, that rapid changes in worker body-ovary size allometry may disrupt queen development and that queen-worker dimorphism arises mainly from discrete nurse-provided nutritional environments, not from a developmental switch that converts variable nutritional environments into discrete phenotypes. Both larval and nurse components have likely contributed to the evolution of queen-worker dimorphism.

  5. Child patterns of growth delay and cognitive development in a Bolivian mining city.

    Science.gov (United States)

    Ruiz-Castell, María; Carsin, Anne-Elie; Barbieri, Flavia-Laura; Paco, Pamela; Gardon, Jacques; Sunyer, Jordi

    2013-01-01

    This study aims to (1) follow up and characterize infant growth patterns during the first year of life in Bolivia, and (2) determine whether there exists an association between weight gain and cognitive development in children living near contaminated mining industries. Data on 175 children participating to the ToxBol (Toxicity in Bolivia) birth cohort were analyzed. Rapid-growth during the first 6 months was defined as a change in weight z-score > 0.67 while slow-growth was defined as a weight z-score change of Development at 10.5-12.5 months of age. Mixed models were used to examine the association between cognitive development and weight gain. Rapid growers weighed less at birth (P cognitive development (coef = 0.49, 95% confidence interval = -4.10, 5.08). In this Bolivian cohort, children born smaller were more likely to grow/develop faster and attain greater weight and length. Their cognitive development was not affected by their growth patterns. Copyright © 2012 Wiley Periodicals, Inc.

  6. Deletion of OTX2 in neural ectoderm delays anterior pituitary development

    Science.gov (United States)

    Mortensen, Amanda H.; Schade, Vanessa; Lamonerie, Thomas; Camper, Sally A.

    2015-01-01

    OTX2 is a homeodomain transcription factor that is necessary for normal head development in mouse and man. Heterozygosity for loss-of-function alleles causes an incompletely penetrant, haploinsufficiency disorder. Affected individuals exhibit a spectrum of features that range from developmental defects in eye and/or pituitary development to acephaly. To investigate the mechanism underlying the pituitary defects, we used different cre lines to inactivate Otx2 in early head development and in the prospective anterior and posterior lobes. Mice homozygous for Otx2 deficiency in early head development and pituitary oral ectoderm exhibit craniofacial defects and pituitary gland dysmorphology, but normal pituitary cell specification. The morphological defects mimic those observed in humans and mice with OTX2 heterozygous mutations. Mice homozygous for Otx2 deficiency in the pituitary neural ectoderm exhibited altered patterning of gene expression and ablation of FGF signaling. The posterior pituitary lobe and stalk, which normally arise from neural ectoderm, were extremely hypoplastic. Otx2 expression was intact in Rathke's pouch, the precursor to the anterior lobe, but the anterior lobe was hypoplastic. The lack of FGF signaling from the neural ectoderm was sufficient to impair anterior lobe growth, but not the differentiation of hormone-producing cells. This study demonstrates that Otx2 expression in the neural ectoderm is important intrinsically for the development of the posterior lobe and pituitary stalk, and it has significant extrinsic effects on anterior pituitary growth. Otx2 expression early in head development is important for establishing normal craniofacial features including development of the brain, eyes and pituitary gland. PMID:25315894

  7. Severity of specific language impairment predicts delayed development in number skills.

    Science.gov (United States)

    Durkin, Kevin; Mok, Pearl L H; Conti-Ramsden, Gina

    2013-01-01

    The extent to which mathematical development is dependent upon language is controversial. This longitudinal study investigates the role of language ability in children's development of number skills. Participants were 229 children with specific language impairment (SLI) who were assessed initially at age 7 and again 1 year later. All participants completed measures of psycholinguistic development (expressive and receptive), performance IQ, and the Basic Number Skills subtest of the British Ability Scales. Number skills data for this sample were compared with normative population data. Consistent with predictions that language impairment would impact on numerical development, average standard scores were more than 1 SD below the population mean at both ages. Although the children showed improvements in raw scores at the second wave of the study, the discrepancy between their scores and the population data nonetheless increased over time. Regression analyses showed that, after controlling for the effect of PIQ, language skills explained an additional 19 and 17% of the variance in number skills for ages 7 and 8, respectively. Furthermore, logistic regression analyses revealed that less improvement in the child's language ability over the course of the year was associated with a greater odds of a drop in performance in basic number skills from 7 to 8 years. The results are discussed in relation to the interaction of linguistic and cognitive factors in numerical development and the implications for mathematical education.

  8. Larval helminths in intermediate hosts

    DEFF Research Database (Denmark)

    Fredensborg, Brian Lund; Poulin, R

    2005-01-01

    a reduction in size, caused by crowding, virtually nothing is known about longer-lasting effects after transmission to the definitive host. This study is the first to use in vitro cultivation with feeding of adult trematodes to investigate how numbers of parasites in the intermediate host affect the size......Density-dependent effects on parasite fitness have been documented from adult helminths in their definitive hosts. There have, however, been no studies on the cost of sharing an intermediate host with other parasites in terms of reduced adult parasite fecundity. Even if larval parasites suffer...... and fecundity of adult parasites. For this purpose, we examined two different infracommunities of parasites in crustacean hosts. Firstly, we used experimental infections of Maritrema novaezealandensis in the amphipod, Paracalliope novizealandiae, to investigate potential density-dependent effects in single...

  9. The Larval Stage of Echinococcus Granulosus

    Directory of Open Access Journals (Sweden)

    Mohsen Sokouti

    2015-01-01

    Full Text Available Throughout the life cycle of Echinococcus granulosus, eggs of the parasite cannot mature into adult worms without first passing through the larval stage. Regarding the fact that this stage cannot take place in the definitive host, the eggs must look for an intermediate host, such as humans which are considered accidental intermediate hosts, in order to undergo their vital metamorphosis. In the upper gastrointestinal tract of the intermediate host, including humans (but not that of definitive host, the outer chitinous shells of the hexacanth embryos become lysed, enabling the embryos to penetrate the mucosa of the duodenum and upper jejunum to enter mesentric venule and be carried in the portal stream to the liver. Theoretically, a few of the embryos can enter the lymphatics of the intestinal wall and bypassing the liver through the cisterna chyli (1-3. It is believed that the larger amount of deoxycholic acid in the bile of herbivores and humans conjugated principally with glycine is responsible for lysis of the larva‘s protective center cuticle. On the other hand bile salts of carnivores such as dog are relatively poor in deoxy cholic acid which is linked with urine and have no effect on the cuticle of the larvae, which remain in the bowel lumen and developing into adult worms. Thus unlike what is mostly believed, humans do not serve as definitive hosts for the parasite; yet they carry only the larval forms which later penetrate into the villi of small bowel and form hydatid cyst in any organ of body (4-6.

  10. Follow-up of premature children with high risk for growth and development delay: a multiprofessional assessment

    Directory of Open Access Journals (Sweden)

    Marcia de Freitas

    2010-06-01

    Full Text Available Objective: To describe the activities of a multiprofessional outpatient clinic performed by neonatologist, physiatrist, physical therapist, occupational therapist, speech therapist, audiologist and psychologist, who evaluated the development of premature newborns. Methods: Twenty children born at a tertiary-care hospital (São Paulo, Brazil, between April 2006 and April 2007, with birth weight below 1250 g or less than 32 weeks of gestation, were evaluated. The multiprofessional evaluation included assessment of development using the Bayley III scale, at the corrected age of 3, 6, 9, 12, 18 and 24 months. Results: The mean gestation age at birth was 28.8 weeks; mean birth weight was 1055 g. The mean maternal age was 35 years and the mean length of stay of neonates was 46.3 days. Fifteen percent of children presented impaired sensory motor skills, 20% had hearing abnormalities and 10% motor alterations. Bayley III showed alterations in the communication area in 10% of subjects and in the motor area in 10% of individuals. The parents were oriented to stimulate the child or a specific intervention was suggested. The major development delay was observed between 6 and 18 months of age and the development was improved at 24 months of age. Conclusions: Most children evaluated had improved growth and development at 24 corrected-age months. Further studies with a larger sample are recommended, as well as the possibility to follow this population group up till the primary school.

  11. The Missing Link: Delayed Emotional Development Predicts Challenging Behavior in Adults with Intellectual Disability

    Science.gov (United States)

    Sappok, Tanja; Budczies, Jan; Dziobek, Isabel; Bölte, Sven; Dosen, Anton; Diefenbacher, Albert

    2014-01-01

    Individuals with intellectual disability (ID) show high rates of challenging behavior (CB). The aim of this retrospective study was to assess the factors underlying CB in an adult, clinical ID sample (n = 203). Low levels of emotional development (ED), as measured by the "Scheme of Appraisal of ED," predicted overall CB, specifically…

  12. Incidence, prevalence, diagnostic delay, and clinical presentation of female 46,XY disorders of sex development

    DEFF Research Database (Denmark)

    Berglund, Agnethe; Johannsen, Trine H; Krag, Kirstine Stochholm

    2016-01-01

    , prevalence, age at diagnosis, and clinical presentation at diagnosis in 46,XY females. DESIGN AND SETTING: A nationwide study covering all known females with a 46,XY karyotype in Denmark since 1960. The diagnosis of 46,XY disorder of sex development (DSD) was determined by medical record evaluation, data...

  13. Delay in early infant motor development in last two decades is not associated with childhood overweight

    NARCIS (Netherlands)

    Brouwer, Silvia I.; Lemmink, Koen; Bartelds, Meike; Geus, Eco de; Boomsma, Dorret; Corpeleijn, Eva; Stolk, Ronald

    2014-01-01

    26737: Introduction The aim of this study was to find out if early motor development has changed over the last decades and how it’s related to overweight during childhood. Method Data from twins participating in the Young Netherlands Twin Register (YNTR) was used. One of the twin pairs born between

  14. The Role of Ego Development in Psychosocial Adjustment among Boys with Delayed Puberty

    Science.gov (United States)

    Lindfors, Kaj; Elovainio, Marko; Wickman, Sanna; Vuorinen, Risto; Sinkkonen, Jari; Dunkel, Leo; Raappana, Aleksi

    2007-01-01

    This study examined the role of ego development, as measured with the Washington University sentence completion test, in the relationship between pubertal maturation and psychosocial adjustment (self-image and depression) in adolescent boys. The data consisted of 73 boys between 14 and 16 years of age. The results indicated that late maturing boys…

  15. Zygote development after delayed fertilization. A cytological and genetical analysis of embryos of the mouse.

    NARCIS (Netherlands)

    Boerjan, M.

    1990-01-01

    Chapter I gives (1) a brief review of morphological and molecular changes in mammalian oocytes initiated by fertilization, (2) a summary of published data on several aspects of post-ovulatory ageing in relation to embryonic development and (3) a description of methods to time ov

  16. 盐度对黄鲷胚胎发育及早期仔鱼生长的影响%Effect of salinity on embryonic development and larval growth of Dentex tumifrons Temminck et Schlegel

    Institute of Scientific and Technical Information of China (English)

    施兆鸿; 夏连军; 王建钢; 陆建学; 赵荣兴; 王海平; 谢立峰

    2004-01-01

    The effect of salinity on embryo and early larva development of Dentex tumiforns was discussed. Floating forms of egg in different salinities, optimal salinity for embryonic development and early larva growth was studied. The results showed: 1. In immobile condition, all eggs sank at salinity of 32.0, most of egg ssuspended in the middle of water at 34.0, and all eggs floated on the surface when salinity above 36.0. 2. Eggs did not hatch out at salinity of below 10.0 or above 60.0 and the death time of egg gradually moved up with increase or decline of salinity. Eggs hatched out at salinity range of 15.0 and 50.0, including abnormal larva. There was indistinct difference in speed of embryonic development (about 36-40h) within the salinity of 15.0 and 50.0. However the salinity had a great effect on larval survival after hatching and abnormal rate. The relation between hatching rate and salinity variation showed parabola but abnormal rate showed inverted parabola. The hatching rate was 81%-86% and abnormal rate of yolk sac larva was 27%-30% in suitable salinities of 27.0-39.0. The hatching rate was 89%-91% and abnormal rate was 13%-16% in optimal salinities of 33.0-36.0. The oil ball of abnormal larva was located in the central or front position. With increased extent of salinity, spondyle of larva bended and number of larva with arrhythmia increased. 3. The optimal salinities were 30.0-35.0 based on SAI. The test with SAI showed that SAI of early larvae was 41.25-47.53 at salinities of 30.0-35.0, the yolk and oil ball of 7-8 days larva was completely absorbed with a survival rate of 88%.

  17. RECENT CONTROVERSIES REGARDING THE DELAYS IN THE ECONOMIC DEVELOPMENT OF THE COUNTRIES FROM EASTERN EUROPE

    OpenAIRE

    Richiter Adriana

    2012-01-01

    The European integration is the best way for the poor Eastern European societies to follow in order to progress. Gathering contacts with the Occident cannot push the former communist societies to the status of chronically backward peripheries. The theory of "modernization" claims that the mere contact with the western modernity is sufficient to remove the elements of the traditional societies which hinder the development and generate progress automatically. Countries, which suffered from th...

  18. The effect of salinity on larval development of Uca tangeri (Eydoux, 1835 (Brachyura: Ocypodidae and new findings of the zoeal morphology

    Directory of Open Access Journals (Sweden)

    Eduardo D. Spivak

    2009-06-01

    Full Text Available In order to evaluate their tolerance to low salinities, zoeae of the fiddler crab Uca tangeri from the Rio San Pedro population (southwestern Spain were reared in the laboratory at 20ºC and at three salinities (16, 24 and 32. The zoeal development was completed at 24 and 32 but the crabs died as zoea I or zoea II, and very rarely as zoea III, at 16; tolerance to low salinities varied among clutches produced by different females. The duration of the first zoeal stage and of the complete zoeal development was shorter at 32. Our observations showed that the zoeae of U. tangeri could not tolerate retention in the mesohaline water of estuaries, and that export to oceanic waters would be optimal for their successful development. Survival at 24 suggests that larvae could also develop in polyhaline conditions if they were retained in the ocean-estuary interface. The presence of an additional zoeal stage (zoea VI was observed in some individuals and associated with unfavourable combinations of temperature and salinity. In addition, some previously omitted aspects of zoeal morphology were re-described and illustrated, providing new evidence which supports the basal position of this species in a proto-Atlantic origin of the genus Uca. It is proposed that the differences between Uca tangeri and the rest of the Uca species should be highlighted, and that it should be placed in its own genus as Afruca tangeri.

  19. Suppression of Brugia malayi (sub-periodic larval development in Aedes aegypti (Liverpool strain fed on blood of animals immunized with microfilariae

    Directory of Open Access Journals (Sweden)

    K Athisaya Mary

    2005-07-01

    Full Text Available Preliminary studies were carried out to investigate the role of filarial specific antibodies, raised in an animal model against the filarial parasite, Brugia malayi (sub-periodic, in blocking their early development in an experimental mosquito host, Aedes aegypti (Liverpool strain. In order to generate filarial specific antibodies, Mongolian gerbils, Meriones unguiculatus, were immunized either with live microfilariae (mf of B. malayi or their homogenate. Mf were harvested from the peritoneal cavity of Mongolian gerbils with patent infection of B. malayi and fed to A. aegypti along with the blood from immunized animals. Development of the parasite in infected mosquitoes was monitored until they reached infective stage larvae (L3. Fewer number of parasites developed to first stage (L1 and subsequently to L2 and L3 in mosquitoes fed with blood of immunized animals, when compared to those fed with blood of control animals. The results thus indicated that filarial parasite specific antibodies present in the blood of the immunized animals resulted in the reduction of number of larvae of B. malayi developing in the mosquito host.

  20. Catching prey with the antennae - The larval head of Corethrella appendiculata (Diptera: Corethrellidae).

    Science.gov (United States)

    Förster, Maria; Beutel, Rolf G; Schneeberg, Katharina

    2016-11-01

    The larval cephalic morphology of Corethrella appendiculata Grabham, 1906 is described and documented in detail. The observed features are compared to conditions found in Chaoboridae, Culicidae, and other culicomorph families. The function of antennae, mouthparts and associated muscles is interpreted based on the morphological results. The prey catching mechanism is compared to what occurs in other predaceous larvae of Culicomorpha. The cephalic larval morphology is discussed with respect to homology and possible phylogenetic implications. The horizontal frontoclypeal antennal grooves and the lateral rows of strongly developed bristles are likely larval autapomorphies of Corethrellidae. The presence of raptorial antennae is a highly unusual apomorphy shared with Chaoboridae. The systematic position of Corethrellidae remains ambiguous.

  1. Larval intraspecific competition for food in the European grapevine moth Lobesia botrana.

    Science.gov (United States)

    Thiéry, D; Monceau, K; Moreau, J

    2014-08-01

    Effective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tested by rearing different numbers of larvae on an artificial diet and measuring developmental and reproductive life history traits. We found that intraspecific competition during larval development has a slight impact on the fitness of L. botrana. The principal finding of this work is that larval density has little effect on the life history traits of survivors. Thus, the timing of eclosion, duration of subsequent oviposition, fecundity appears to be more uniform in L. botrana than in other species. The main effect of larval crowding was a strong increase of larval mortality at high densities whereas the probability of emergence, sex ratio, pupal mass, fecundity and longevity of mated females were not affected by larval crowding. Owing to increased larval mortality at high larval densities, we hypothesized that mortality of larvae at high densities provided better access to food for the survivors with the result that more food was available per capita and there were no effect on fitness of survivors. From our results, larval crowding alters the reproductive capacity of this pest less than expected but this single factor should now be tested in interaction with limited resources in the wild.

  2. Development and implementation of mass media campaigns to delay sexual initiation among African American and White youth.

    Science.gov (United States)

    Noar, Seth M; Zimmerman, Rick S; Palmgreen, Philip; Cupp, Pamela K; Floyd, Brenikki R; Mehrotra, Purnima

    2014-01-01

    Reducing new HIV/STD infections among at-risk adolescents requires developing and evaluating evidence-based health communication approaches. Research overwhelmingly supports the conclusion that early sexual initiation is associated with STDs and other negative outcomes in later years (e.g., unintended pregnancy). The authors' research group secured funding from the National Institute of Mental Health to develop, implement, and rigorously evaluate televised mass media campaigns to delay initiation of sexual intercourse among African American and White adolescents in two cities in the Southeastern United States. The focus of the present study is on the development and implementation of the campaigns, including (a) rationale and theoretical underpinnings; (b) collection, screening, and assessment of existing public service announcements; (c) development of new public service announcements; (d) study design and campaign airing plan; and (e) message exposure achieved in the campaigns. Health communication campaigns hold much promise in reaching at-risk adolescent populations with targeted, timely, and relevant risk-reduction messages.

  3. Temperature control of larval dispersal and the implications for marine ecology, evolution, and conservation.

    Science.gov (United States)

    O'Connor, Mary I; Bruno, John F; Gaines, Steven D; Halpern, Benjamin S; Lester, Sarah E; Kinlan, Brian P; Weiss, Jack M

    2007-01-23

    Temperature controls the rate of fundamental biochemical processes and thereby regulates organismal attributes including development rate and survival. The increase in metabolic rate with temperature explains substantial among-species variation in life-history traits, population dynamics, and ecosystem processes. Temperature can also cause variability in metabolic rate within species. Here, we compare the effect of temperature on a key component of marine life cycles among a geographically and taxonomically diverse group of marine fish and invertebrates. Although innumerable lab studies document the negative effect of temperature on larval development time, little is known about the generality versus taxon-dependence of this relationship. We present a unified, parameterized model for the temperature dependence of larval development in marine animals. Because the duration of the larval period is known to influence larval dispersal distance and survival, changes in ocean temperature could have a direct and predictable influence on population connectivity, community structure, and regional-to-global scale patterns of biodiversity.

  4. Metamorphosis in Craniiformea revisited: Novocrania anomala shows delayed development of the ventral valve

    DEFF Research Database (Denmark)

    Altenburger, Andreas; Wanninger, Andreas Wilhelm Georg; Holmer, Lars E.

    2013-01-01

    the Rhynchonelliformea. This interpretation suggests that the last common ancestor of the Craniiformea has lost the pedicle and the ventral valve in early juvenile development. Characters that have previously been considered to be shared between the Craniiformea and the Linguliformea (clade Inarticulata...... brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda...

  5. Proteomics Insights: Proteins related to Larval Attachment and Metamorphosis of Marine Invertebrates

    Directory of Open Access Journals (Sweden)

    KONDETHIMMANAHALLI eCHANDRAMOULI

    2014-10-01

    Full Text Available The transition in an animal from a pelagic larval stage to a sessile benthic juvenile typically requires major morphological and behavioral changes. Larval competency, attachment and initiation of metamorphosis are thought to be regulated by intrinsic chemical signals and specific sets of proteins. However, the molecular mechanisms that regulate larval attachment and metamorphosis in marine invertebrates have yet to be fully elucidated. Despite the many challenges associated with analysis of the larvae proteome, recent proteomic technologies have been used to address specific questions in larval developmental biology. These and other molecular studies have generated substantial amount of information of the proteins and molecular pathways involved in larval attachment and metamorphosis. Furthermore, the results of these studies have shown that systematic changes in protein expression patterns and post-translational modifications (PTM are crucial for the transition from larva to juvenile. The degeneration of larval tissues is mediated by protein degradation, while the development of juvenile organs may require PTM. In terms of application, the identified proteins may serve as targets for antifouling compounds, and biomarkers for environmental stressors. In this review we highlight the strengths and limitations of proteomic tools in the context of the study of marine invertebrate larval biology.

  6. Proteomics insights: proteins related to larval attachment and metamorphosis of marine invertebrates

    KAUST Repository

    Chandramouli, Kondethimmanahalli

    2014-10-31

    The transition in an animal from a pelagic larval stage to a sessile benthic juvenile typically requires major morphological and behavioral changes. Larval competency, attachment and initiation of metamorphosis are thought to be regulated by intrinsic chemical signals and specific sets of proteins. However, the molecular mechanisms that regulate larval attachment and metamorphosis in marine invertebrates have yet to be fully elucidated. Despite the many challenges associated with analysis of the larvae proteome, recent proteomic technologies have been used to address specific questions in larval developmental biology. These and other molecular studies have generated substantial amount of information of the proteins and molecular pathways involved in larval attachment and metamorphosis. Furthermore, the results of these studies have shown that systematic changes in protein expression patterns and post-translational modifications (PTMs) are crucial for the transition from larva to juvenile. The degeneration of larval tissues is mediated by protein degradation, while the development of juvenile organs may require PTM. In terms of application, the identified proteins may serve as targets for antifouling compounds, and biomarkers for environmental stressors. In this review we highlight the strengths and limitations of proteomic tools in the context of the study of marine invertebrate larval biology.

  7. Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

    Science.gov (United States)

    Tariq, K; Noor, M; Hori, M; Ali, A; Hussain, A; Peng, W; Chang, C-J; Zhang, H

    2017-05-09

    Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

  8. Implicit Memory in Monkeys: Development of a Delay Eyeblink Conditioning System with Parallel Electromyographic and High-Speed Video Measurements.

    Directory of Open Access Journals (Sweden)

    Yasushi Kishimoto

    Full Text Available Delay eyeblink conditioning, a cerebellum-dependent learning paradigm, has been applied to various mammalian species but not yet to monkeys. We therefore developed an accurate measuring system that we believe is the first system suitable for delay eyeblink conditioning in a monkey species (Macaca mulatta. Monkey eyeblinking was simultaneously monitored by orbicularis oculi electromyographic (OO-EMG measurements and a high-speed camera-based tracking system built around a 1-kHz CMOS image sensor. A 1-kHz tone was the conditioned stimulus (CS, while an air puff (0.02 MPa was the unconditioned stimulus. EMG analysis showed that the monkeys exhibited a conditioned response (CR incidence of more than 60% of trials during the 5-day acquisition phase and an extinguished CR during the 2-day extinction phase. The camera system yielded similar results. Hence, we conclude that both methods are effective in evaluating monkey eyeblink conditioning. This system incorporating two different measuring principles enabled us to elucidate the relationship between the actual presence of eyelid closure and OO-EMG activity. An interesting finding permitted by the new system was that the monkeys frequently exhibited obvious CRs even when they produced visible facial signs of drowsiness or microsleep. Indeed, the probability of observing a CR in a given trial was not influenced by whether the monkeys closed their eyelids just before CS onset, suggesting that this memory could be expressed independently of wakefulness. This work presents a novel system for cognitive assessment in monkeys that will be useful for elucidating the neural mechanisms of implicit learning in nonhuman primates.

  9. Experimental drought and heat can delay phenological development and reduce foliar and shoot growth in semiarid trees.

    Science.gov (United States)

    Adams, Henry D; Collins, Adam D; Briggs, Samuel P; Vennetier, Michel; Dickman, L Turin; Sevanto, Sanna A; Garcia-Forner, Núria; Powers, Heath H; McDowell, Nate G

    2015-11-01

    Higher temperatures associated with climate change are anticipated to trigger an earlier start to the growing season, which could increase the terrestrial C sink strength. Greater variability in the amount and timing of precipitation is also expected with higher temperatures, bringing increased drought stress to many ecosystems. We experimentally assessed the effects of higher temperature and drought on the foliar phenology and shoot growth of mature trees of two semiarid conifer species. We exposed field-grown trees to a ~45% reduction in precipitation with a rain-out structure ('drought'), a ~4.8 °C temperature increase with open-top chambers ('heat'), and a combination of both simultaneously ('drought + heat'). Over the 2013 growing season, drought, heat, and drought + heat treatments reduced shoot and needle growth in piñon pine (Pinus edulis) by ≥39%, while juniper (Juniperus monosperma) had low growth and little response to these treatments. Needle emergence on primary axis branches of piñon pine was delayed in heat, drought, and drought + heat treatments by 19-57 days, while secondary axis branches were less likely to produce needles in the heat treatment, and produced no needles at all in the drought + heat treatment. Growth of shoots and needles, and the timing of needle emergence correlated inversely with xylem water tension and positively with nonstructural carbohydrate concentrations. Our findings demonstrate the potential for delayed phenological development and reduced growth with higher temperatures and drought in tree species that are vulnerable to drought and reveal potential mechanistic links to physiological stress responses. Climate change projections of an earlier and longer growing season with higher temperatures, and consequent increases in terrestrial C sink strength, may be incorrect for regions where plants will face increased drought stress with climate change.

  10. Delayed development of systemic immunity in preterm pigs as a model for preterm infants

    DEFF Research Database (Denmark)

    Nguyen, Duc Ninh; Jiang, Pingping; Frøkiær, Hanne;

    2016-01-01

    Preterm neonates are highly sensitive to systemic infections in early life but little is known about systemic immune development following preterm birth. We hypothesized that preterm neonates have immature systemic immunity with distinct developmental trajectory for the first several weeks of life......, relative to those born at near-term or term. Using pigs as a model, we characterized blood leukocyte subsets, antimicrobial activities and TLR-mediated cytokine production during the first weeks after preterm birth. Relative to near-term and term pigs, newborn preterm pigs had low blood leukocyte counts......, poor neutrophil phagocytic rate, and limited cytokine responses to TLR1/2/5/7/9 and NOD1/2 agonists. The preterm systemic responses remained immature during the first postnatal week, but thereafter showed increased blood leukocyte numbers, NK cell proportion, neutrophil phagocytic rate and TLR2...

  11. Delayed development of systemic immunity in preterm pigs as a model for preterm infants

    DEFF Research Database (Denmark)

    Nguyen, Duc Ninh; Jiang, Pingping; Frøkiær, Hanne

    2016-01-01

    Preterm neonates are highly sensitive to systemic infections in early life but little is known about systemic immune development following preterm birth. We hypothesized that preterm neonates have immature systemic immunity with distinct developmental trajectory for the first several weeks of life......, relative to those born at near-term or term. Using pigs as a model, we characterized blood leukocyte subsets, antimicrobial activities and TLR-mediated cytokine production during the first weeks after preterm birth. Relative to near-term and term pigs, newborn preterm pigs had low blood leukocyte counts......, poor neutrophil phagocytic rate, and limited cytokine responses to TLR1/2/5/7/9 and NOD1/2 agonists. The preterm systemic responses remained immature during the first postnatal week, but thereafter showed increased blood leukocyte numbers, NK cell proportion, neutrophil phagocytic rate and TLR2...

  12. Suppression of the transcription factor MSX1 gene delays bovine preimplantation embryo development in vitro.

    Science.gov (United States)

    Tesfaye, D; Regassa, A; Rings, F; Ghanem, N; Phatsara, C; Tholen, E; Herwig, R; Un, C; Schellander, K; Hoelker, M

    2010-05-01

    This study was conducted to investigate the effect of suppressing transcription factor gene MSX1 on the development of in vitro produced bovine oocytes and embryos, and identify its potential target genes regulated by this gene. Injection of long double-stranded RNA (LdsRNA) and small interfering RNA (siRNA) at germinal vesicle stage oocyte reduced MSX1 mRNA expression by 73 and 37% respectively at metaphase II stage compared with non-injected controls. Similarly, injection of the same anti-sense oligomers at zygote stage reduced MSX1 mRNA expression by 52 and 33% at 8-cell stage compared with non-injected controls. Protein expression was also reduced in LdsRNA- and siRNA-injected groups compared with non-injected controls at both stages. Blastocysts rates were 33, 28, 20 and 18% in non-injected control, scrambled RNA (scRNA), LdsRNA- and siRNA-injected groups respectively. Cleavage rates were also significantly reduced in Smartpool siRNA (SpsiRNA)-injected group (53.76%) compared with scRNA-injected group (57.76%) and non-injected control group (61%). Large-scale gene expression analysis showed that 135 genes were differentially regulated in SpsiRNA-injected group compared with non-injected controls, of which 54 and 81 were down- and up-regulated respectively due to suppression of MSX1. Additionally, sequence homology mapping and gene enrichment analysis with known human pathway information identified several functional modules that were affected due to suppression of MSX1. In conclusion, suppression of MSX1 affects oocyte maturation, embryo cleavage rate and the expression of several genes, suggesting its potential role in the development of bovine preimplantation embryos.

  13. High gene flow due to pelagic larval dispersal among South Pacific archipelagos in two amphidromous gastropods (Neritomorpha: Neritidae).

    Science.gov (United States)

    Crandall, E D; Taffel, J R; Barber, P H

    2010-06-01

    The freshwater stream fauna of tropical oceanic islands is dominated by amphidromous species, whose larvae are transported to the ocean and develop in the plankton before recruiting back to freshwater habitat as juveniles. Because stream habitat is relatively scarce and unstable on oceanic islands, this life history would seem to favor either the retention of larvae to their natal streams, or the ability to delay metamorphosis until new habitat is encountered. To distinguish between these hypotheses, we used population genetic methods to estimate larval dispersal among five South Pacific archipelagos in two amphidromous species of Neritid gastropod (Neritina canalis and Neripteron dilatatus). Sequence data from mitochondrial cytochrome oxidase I (COI) revealed that neither species is genetically structured throughout the Western Pacific, suggesting that their larvae have a pelagic larval duration (PLD) of at least 8 weeks, longer than many marine species. In addition, the two species have recently colonized isolated Central Pacific archipelagos in three independent events. Since colonization, there has been little or no gene flow between the Western and Central Pacific archipelagos in N. canalis, and high levels of gene flow across the same region in N. dilatatus. Both species show departures from neutrality and recent dates for colonization of the Central Pacific archipelagos, which is consistent with frequent extinction and recolonization of stream populations in this area. Similar results from other amphidromous species suggest that unstable freshwater habitats promote long-distance dispersal capabilities.

  14. The complete larval development of Armases benedicti (Rathbun (Decapoda, Sesarmidae, from the Amazon region, reared in the laboratory O desenvolvimento larval completo de Armases benedicti (Rathbun (Decapoda, Sesarmidae, da região Amazônica, obtido em laboratório

    Directory of Open Access Journals (Sweden)

    Jô de F. Lima

    2006-06-01

    Full Text Available The four zoeal and one megalopal stages of the wharf crab Armases benedicti (Rathbun, 1897 larvae reared in the laboratory are described and illustrated in detail. The mean duration for each larval stage was 3, 2, 4, 4 and 13 days, respectively. The duration of the larval period from hatching to the first juvenile was 26 days. Morphologically, A. benedicti is very similar to the reported species of genus. However, a small lateral spine is clearly observed in the carapace of zoeal stages of this species. This feature appears to be unique among the family Sesarmidae. Another distinctive character for this species is the zoeal setation of the maxilla endopod (2+2 in which most of the sesarmids have setation (2+3 except for Sesarma tetragonum (Fabricius, 1798. Other comparisons with previous larval studies of the genus Armases Abele, 1992 are briefly discussed.São descritos e ilustrados em detalhes, os quatro estágios de zoea e um de megalopa do caranguejo Armases benedicti (Rathbun, 1897, a partir de larvas obtidas em laboratório. A média de duração de cada estágio larval foi 3, 2, 4, 4 e 13 dias, respectivamente. O período compreendido desde a eclosão até o surgimento do primeiro juvenil foi de 26 dias. Morfologicamente A. benedicti é muito similar às outras espécies do gênero, contudo, um pequeno espinho lateral é claramente observado na carapaça das zoeas desta espécie. Esta característica aparenta ser única dentre os Sesarmidae. Outra característica distinta desta espécie é a distribuição das cerdas do endópodo da maxila (2+2, o qual difere dos demais sesarmídeos que apresentam a distribuição (2+3, exceto para Sesarma tetragonum (Fabricius, 1798 o qual apresenta (2+2. Outras comparações morfológicas com trabalhos anteriores relacionados a larvas do gênero Armases Abele, 1992 são brevemente discutidas.

  15. Mosquito larval source management for controlling malaria.

    Science.gov (United States)

    Tusting, Lucy S; Thwing, Julie; Sinclair, David; Fillinger, Ulrike; Gimnig, John; Bonner, Kimberly E; Bottomley, Christian; Lindsay, Steven W

    2013-08-29

    Malaria is an important cause of illness and death in people living in many parts of the world, especially sub-Saharan Africa. Long-lasting insecticide treated bed nets (LLINs) and indoor residual spraying (IRS) reduce malaria transmission by targeting the adult mosquito vector and are key components of malaria control programmes. However, mosquito numbers may also be reduced by larval source management (LSM), which targets mosquito larvae as they mature in aquatic habitats. This is conducted by permanently or temporarily reducing the availability of larval habitats (habitat modification and habitat manipulation), or by adding substances to standing water that either kill or inhibit the development of larvae (larviciding). To evaluate the effectiveness of mosquito LSM for preventing malaria. We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CABS Abstracts; and LILACS up to 24 October 2012. We handsearched the Tropical Diseases Bulletin from 1900 to 2010, the archives of the World Health Organization (up to 11 February 2011), and the literature database of the Armed Forces Pest Management Board (up to 2 March 2011). We also contacted colleagues in the field for relevant articles. We included cluster randomized controlled trials (cluster-RCTs), controlled before-and-after trials with at least one year of baseline data, and randomized cross-over trials that compared LSM with no LSM for malaria control. We excluded trials that evaluated biological control of anopheline mosquitoes with larvivorous fish. At least two authors assessed each trial for eligibility. We extracted data and at least two authors independently determined the risk of bias in the included studies. We resolved all disagreements through discussion with a third author. We analyzed the data using Review Manager 5 software. We included 13 studies; four cluster-RCTs, eight controlled before

  16. Mosquito larval source management for controlling malaria

    Science.gov (United States)

    Tusting, Lucy S; Thwing, Julie; Sinclair, David; Fillinger, Ulrike; Gimnig, John; Bonner, Kimberly E; Bottomley, Christian; Lindsay, Steven W

    2015-01-01

    Background Malaria is an important cause of illness and death in people living in many parts of the world, especially sub-Saharan Africa. Long-lasting insecticide treated bed nets (LLINs) and indoor residual spraying (IRS) reduce malaria transmission by targeting the adult mosquito vector and are key components of malaria control programmes. However, mosquito numbers may also be reduced by larval source management (LSM), which targets mosquito larvae as they mature in aquatic habitats. This is conducted by permanently or temporarily reducing the availability of larval habitats (habitat modification and habitat manipulation), or by adding substances to standing water that either kill or inhibit the development of larvae (larviciding). Objectives To evaluate the effectiveness of mosquito LSM for preventing malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CABS Abstracts; and LILACS up to 24 October 2012. We handsearched the Tropical Diseases Bulletin from 1900 to 2010, the archives of the World Health Organization (up to 11 February 2011), and the literature database of the Armed Forces Pest Management Board (up to 2 March 2011). We also contacted colleagues in the field for relevant articles. Selection criteria We included cluster randomized controlled trials (cluster-RCTs), controlled before-and-after trials with at least one year of baseline data, and randomized cross-over trials that compared LSM with no LSM for malaria control. We excluded trials that evaluated biological control of anopheline mosquitoes with larvivorous fish. Data collection and analysis At least two authors assessed each trial for eligibility. We extracted data and at least two authors independently determined the risk of bias in the included studies. We resolved all disagreements through discussion with a third author. We analyzed the data using Review Manager 5 software

  17. The lethal giant larvae Gene in Tribolium castaneum: Molecular Properties and Roles in Larval and Pupal Development as Revealed by RNA Interference

    Directory of Open Access Journals (Sweden)

    Da Xiao

    2014-04-01

    Full Text Available We identified and characterized the TcLgl gene putatively encoding lethal giant larvae (Lgl protein from the red flour beetle (Tribolium castaneum. Analyses of developmental stage and tissue-specific expression patterns revealed that TcLgl was constitutively expressed. To examine the role of TcLgl in insect development, RNA interference was performed in early (1-day larvae, late (20-day larvae, and early (1-day pupae. The early larvae injected with double-stranded RNA of TcLgl (dsTcLgl at 100, 200, and 400 ng/larva failed to pupate, and 100% mortality was achieved within 20 days after the injection or before the pupation. The late larvae injected with dsTcLgl at these doses reduced the pupation rates to only 50.3%, 36.0%, and 18.2%, respectively. The un-pupated larvae gradually died after one week, and visually unaffected pupae failed to emerge into adults and died during the pupal stage. Similarly, when early pupae were injected with dsTcLgl at these doses, the normal eclosion rates were reduced to only 22.5%, 18.0%, and 11.2%, respectively, on day 7 after the injection, and all the adults with abnormal eclosion died in two days after the eclosion. These results indicate that TcLgl plays an essential role in insect development, especially during their metamorphosis.

  18. Association between feeding difficulties and language delay in preterm infants using Bayley Scales of Infant Development-Third Edition.

    Science.gov (United States)

    Adams-Chapman, Ira; Bann, Carla M; Vaucher, Yvonne E; Stoll, Barbara J

    2013-09-01

    To evaluate the relationship between abnormal feeding patterns and language performance on the Bayley Scales of Infant Development-Third Edition at 18-22 months adjusted age among a cohort of extremely premature infants. This is a descriptive analysis of 1477 preterm infants born ≤ 26 weeks gestation or enrolled in a clinical trial between January 1, 2006 and March 18, 2008 at a National Institute of Child Health and Human Development Neonatal Research Network center who completed the 18-month neurodevelopmental follow-up assessment. At 18-22 months adjusted age, a comprehensive neurodevelopmental evaluation was performed by certified examiners including the Receptive and Expressive Language Subscales of the Bayley Scales of Infant Development-Third Edition and a standardized adjusted age feeding behaviors and nutritional intake. Data were analyzed using bivariate and multilevel linear and logistic regression modeling. Abnormal feeding behaviors were reported in 193 (13%) of these infants at 18-22 months adjusted age. Abnormal feeding patterns, days of mechanical ventilation, hearing impairment, and Gross Motor Functional Classification System level ≥ 2 each independently predicted lower composite language scores. At 18 months adjusted age, premature infants with a history of feeding difficulties are more likely to have language delay. Neuromotor impairment and days of mechanical ventilation are both important risk factors associated with these outcomes. Copyright © 2013 Mosby, Inc. All rights reserved.

  19. Delayed Root Development by Displaced Mineral Trioxide Aggregate after Regenerative Endodontics: A Case Report.

    Science.gov (United States)

    Timmerman, Aovana; Parashos, Peter

    2017-02-01

    This case report presents the treatment of a 16-year-old boy with a maxillary lateral incisor (tooth #10) presenting with Oehlers type II dens invaginatus and diagnosed with previously initiated therapy and asymptomatic apical periodontitis. A regenerative endodontic procedure (REP) was performed for the tooth but complicated by apically displaced mineral trioxide aggregate (MTA). Clinical and radiographic examination was undertaken yearly, and a cone-beam computed tomography scan was taken to investigate further the formation of hard tissues within the root canal. Subsequently, tooth #10 was re-accessed and then root-filled with MTA. There was complete periapical healing, thickening of the dentinal root walls, and completed apex formation 3 years after REP. Hard tissue formation was noted within the root canal, on the root canal wall, and the root apex through clinical and radiographic examination. Less hard tissue formation was noted on the labial root canal wall where the displaced MTA was located, which was identified on the cone-beam computed tomography scan. This report demonstrates that REP can potentially provide excellent treatment outcomes for structurally compromised teeth. REP should be considered as a first-line treatment before proceeding with a root filling when root development is incomplete, but attention to technical detail is essential. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. A hemocyte-expressed fibrinogen-related protein gene (LvFrep) from the shrimp Litopenaeus vannamei: Expression analysis after microbial infection and during larval development.

    Science.gov (United States)

    Coelho, Jaqueline da Rosa; Barreto, Cairé; Silveira, Amanda da Silva; Vieira, Graziela Cleusa; Rosa, Rafael Diego; Perazzolo, Luciane Maria

    2016-09-01

    Fibrinogen-related proteins (FREPs) comprise a large family of microbial recognition proteins involved in many biological functions in both vertebrate and invertebrate animals. By taking advantage of publicly accessible databases, we have identified a FREP-like homolog in the most cultivated penaeid shrimp, Litopenaeus vannamei (LvFrep). The obtained sequence showed a conserved fibrinogen-related domain (FReD) and displayed significant similarities to FREP-like proteins from other invertebrates and to ficolins from crustaceans. The expression of LvFrep appeared to be limited to circulating hemocytes. Interestingly, LvFrep gene expression was induced in shrimp hemocytes only in response to a Vibrio infection but not to the White spot syndrome virus (WSSV). Moreover, LvFrep transcript levels were detected early in fertilized eggs, suggesting the participation of this immune-related gene in the antimicrobial defenses during shrimp development.

  1. Preliminary observations on the effects of vector-averaged gravity on the embryonic and larval development of the gastropod mollusk, Ilyanassa obsoleta Stimpson

    Science.gov (United States)

    Conrad, G. W.; Stephens, A. P.; Conrad, A. H.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    Fertilized eggs of Ilyanassa obsoleta Stimpson were collected immediately after their deposition in egg capsules. Unopened egg capsules then were affixed to glass slides, and incubated either statically (controls) or on a clinostat (experimentals). After incubation for 9-14 days, hatching occurred sooner and in a higher percentage of clinostated capsules than in controls. Embryos that hatched while undergoing clinostat incubation were abnormal in morphology, whereas other embryos present in non-hatched capsules in the same tubes appeared normal, as did embryos in the control tubes. Although the results are compatible with a conclusion that vector-averaged gravity in the experimental tubes caused the altered development, some other aspects of how the incubations were done may have contributed to the differences between the control and experimental results.

  2. Delay of Gratification: A Comparison Study of Children with Down Syndrome, Moderate Intellectual Disability and Typical Development

    Science.gov (United States)

    Cuskelly, M.; Gilmore, L.; Glenn, S.; Jobling, A.

    2016-01-01

    Background: Self-regulation has been found to be an important contributor to a range of outcomes, with delay of gratification (a self-regulatory skill) predicting better academic, social and personal functioning. There is some evidence that individuals with Down syndrome have difficulty with delay of gratification. We investigated the question of…

  3. Expression of Calmodulin and Myosin Light Chain Kinase during Larval Settlement of the Barnacle Balanus amphitrite

    KAUST Repository

    Chen, Zhang-Fan

    2012-02-13

    Barnacles are one of the most common organisms in intertidal areas. Their life cycle includes seven free-swimming larval stages and sessile juvenile and adult stages. The transition from the swimming to the sessile stages, referred to as larval settlement, is crucial for their survivor success and subsequent population distribution. In this study, we focused on the involvement of calmodulin (CaM) and its binding proteins in the larval settlement of the barnacle, Balanus (= Amphibalanus) amphitrite. The full length of CaM gene was cloned from stage II nauplii of B. amphitrite (referred to as Ba-CaM), encoding 149 amino acid residues that share a high similarity with published CaMs in other organisms. Quantitative real-time PCR showed that Ba-CaM was highly expressed in cyprids, the stage at which swimming larvae are competent to attach and undergo metamorphosis. In situ hybridization revealed that the expressed Ba-CaM gene was localized in compound eyes, posterior ganglion and cement glands, all of which may have essential functions during larval settlement. Larval settlement assays showed that both the CaM inhibitor compound 48/80 and the CaM-dependent myosin light chain kinase (MLCK) inhibitor ML-7 effectively blocked barnacle larval settlement, whereas Ca 2+/CaM-dependent kinase II (CaMKII) inhibitors did not show any clear effects. The subsequent real-time PCR assay showed a higher expression level of Ba-MLCK gene in larval stages than in adults, suggesting an important role of Ba-MLCK gene in larval development and competency. Overall, the results suggest that CaM and CaM-dependent MLCK function during larval settlement of B. amphitrite. © 2012 Chen et al.

  4. Susceptibility of cat fleas (Siphonaptera: Pulicidae) to fipronil and imidacloprid using adult and larval bioassays.

    Science.gov (United States)

    Rust, M K; Vetter, R; Denholm, I; Blagburn, B; Williamson, M S; Kopp, S; Coleman, G; Hostetler, J; Davis, W; Mencke, N; Rees, R; Foit, S; Tetzner, K

    2014-05-01

    The monitoring of the susceptibility offleas to insecticides has typically been conducted by exposing adults on treated surfaces. Other methods such as topical applications of insecticides to adults and larval bioassays on treated rearing media have been developed. Unfortunately, baseline responses of susceptible strains of cat flea, Ctenocephalides felis (Bouchè), except for imidacloprid, have not been determined for all on-animal therapies and new classes of chemistry now being used. However, the relationship between adult and larval bioassays of fleas has not been previously investigated. The adult and larval bioassays of fipronil and imidacloprid were compared for both field-collected isolates and laboratory strains. Adult topical bioassays of fipronil and imidacloprid to laboratory strains and field-collected isolates demonstrated that LD50s of fipronil and imidacloprid ranged from 0.11 to 0.40 nanograms per flea and 0.02 to 0.18 nanograms per flea, respectively. Resistance ratios for fipronil and imidacloprid ranged from 0.11 to 2.21. Based on the larval bioassay published for imidacloprid, a larval bioassay was established for fipronil and reported in this article. The ranges of the LC50s of fipronil and imidacloprid in the larval rearing media were 0.07-0.16 and 0.11-0.21 ppm, respectively. Resistance ratios for adult and larval bioassays ranged from 0.11 to 2.2 and 0.58 to 1.75, respectively. Both adult and larval bioassays provided similar patterns for fipronil and imidacloprid. Although the adult bioassays permitted a more precise dosage applied, the larval bioassays allowed for testing isolates without the need to maintain on synthetic or natural hosts.

  5. Expression of calmodulin and myosin light chain kinase during larval settlement of the Barnacle Balanus amphitrite.

    Directory of Open Access Journals (Sweden)

    Zhang-Fan Chen

    Full Text Available Barnacles are one of the most common organisms in intertidal areas. Their life cycle includes seven free-swimming larval stages and sessile juvenile and adult stages. The transition from the swimming to the sessile stages, referred to as larval settlement, is crucial for their survivor success and subsequent population distribution. In this study, we focused on the involvement of calmodulin (CaM and its binding proteins in the larval settlement of the barnacle, Balanus ( = Amphibalanus amphitrite. The full length of CaM gene was cloned from stage II nauplii of B. amphitrite (referred to as Ba-CaM, encoding 149 amino acid residues that share a high similarity with published CaMs in other organisms. Quantitative real-time PCR showed that Ba-CaM was highly expressed in cyprids, the stage at which swimming larvae are competent to attach and undergo metamorphosis. In situ hybridization revealed that the expressed Ba-CaM gene was localized in compound eyes, posterior ganglion and cement glands, all of which may have essential functions during larval settlement. Larval settlement assays showed that both the CaM inhibitor compound 48/80 and the CaM-dependent myosin light chain kinase (MLCK inhibitor ML-7 effectively blocked barnacle larval settlement, whereas Ca(2+/CaM-dependent kinase II (CaMKII inhibitors did not show any clear effects. The subsequent real-time PCR assay showed a higher expression level of Ba-MLCK gene in larval stages than in adults, suggesting an important role of Ba-MLCK gene in larval development and competency. Overall, the results suggest that CaM and CaM-dependent MLCK function during larval settlement of B. amphitrite.

  6. Immunocytochemistry and metamorphic fate of the larval nervous system of Triphyllozoon mucronatum (Ectoprocta: Gymnolaemata: Cheilostomata)

    DEFF Research Database (Denmark)

    Wanninger, Andreas; Koop, Demian; Degnan, Bernard M.

    2005-01-01

    The development of gymnolaemate Ectoprocta includes a larval stage of either the coronate or the cyphonautes type. Herein, we provide the first description of the larval neural anatomy of a coronate larva using immunocytochemical methods. We used antibodies against the neurotransmitters serotonin...

  7. How the early sporulation sigma factor sigmaF delays the switch to late development in Bacillus subtilis.

    Science.gov (United States)

    Karmazyn-Campelli, Céline; Rhayat, Lamya; Carballido-López, Rut; Duperrier, Sandra; Frandsen, Niels; Stragier, Patrick

    2008-03-01

    Sporulation in Bacillus subtilis is a primitive differentiation process involving two cell types, the forespore and the mother cell. Each cell implements two successive transcription programmes controlled by specific sigma factors. We report that activity of sigma(G), the late forespore sigma factor, is kept in check by Gin, the product of csfB, a gene controlled by sigma(F), the early forespore sigma factor. Gin abolishes sigma(G) transcriptional activity when sigma(G) is artificially synthesized during growth, but has no effect on sigma(F). Gin interacts strongly with sigma(G) but not with sigma(F) in a yeast two-hybrid experiment. The absence of Gin allows sigma(G) to be active during sporulation independently of the mother-cell development to which it is normally coupled. Premature sigma(G) activity leads to the formation of slow-germinating spores, and complete deregulation of sigma(G) synthesis is lethal when combined with gin inactivation. Gin allows sigma(F) to delay the switch to the late forespore transcription programme by preventing sigma(G) to take over before the cell has reached a critical stage of development. A similar strategy, following a completely unrelated route, is used by the mother cell.

  8. Delayed development of spontaneous seizures and prolonged convulsive state in rats after massed stimulation of the anterior piriform cortex.

    Science.gov (United States)

    Timofeeva, O A; Peterson, G M

    1997-04-18

    We studied the short- and long-term epileptogenic effects of massed stimulation (MS) of the piriform cortex. Sprague-Dawley rats with electrodes implanted bilaterally in the anterior piriform cortex and the dorsal and ventral hippocampi underwent MS: electrical stimulation of the left piriform cortex every 5 min for 6 h (afterdischarge threshold, 60 Hz, 1 ms, 1 s). Animals were retested (5 stimulations) 3-4 times later at different time points to check for the kindled state. Our data showed that MS resulted in delayed development of severe epilepsy. The interval between MS and the first appearance of convulsive response (2 weeks) was characterized by deep refractoriness to seizure (silent period). Unexpectedly, dramatic seizure activity occurred 4-7 weeks after MS. This was manifested by (1) generalized tonic-clonic convulsions with multiple failings, which were elicited repeatedly during retest; (2) frequent progression of elicited generalized convulsions into a prolonged (> 8 min) postictal convulsive state expressed mainly by continuous partial seizures and even new bouts of generalized seizures, and (3) development of mild spontaneous seizures. We found that epileptiform activity predominated in the ventral hippocampus. Mossy fiber sprouting was also most pronounced in this area. We propose that the MS resulted in formation of pathological circuits which involve both piriform cortex and ventral hippocampus and lead to severe epilepsy.

  9. Hatching and larval export of the intertidal crab Neohelice granulata in Mar Chiquita coastal lagoon, Argentina

    OpenAIRE

    Guillermina Sánchez Vuichard; Nahuel Farías; Tomás Luppi

    2013-01-01

    Synchronization in the events of the reproductive cycle in female Neohelice granulata Dana, 1851 were studied from samples taken weekly and biweekly from September to December 2006 in the Laguna Mar Chiquita. The timing and larval hatching and synchronicity were inferred from numbers of ovigerous females and observing the stages of embryonic development. Synchronization in larval hatching also was observed in females in experiments in dark for a period of 48 hours, at three different saliniti...

  10. Behavioral ecology of larval dragonflies and damselflies.

    Science.gov (United States)

    Johnson, D M

    1991-01-01

    During the past decade, larval dragonflies and damselflies (Insecta: Odonata) have been the subjects for very productive ecological research. Descriptive field work, enclosure experiments and laboratory behavior studies have identified fish predation, intraguild predation (especially mutual predation among odonates, including cannibalism) and interference competition as particularly strong interactions influencing larval odonate assemblages. Behavioral differences among species suggest evolutionary adaptations for coexistence with different predators, and for winning intraspecific aggressive encounters.

  11. Development of a Low-cost, FPGA-based, Delay Line Particle Detector for Satellite and Sounding Rocket Applications

    Science.gov (United States)

    Harrington, M.; Kujawski, J. T.; Adrian, M. L.; Weatherwax, A. T.

    2013-12-01

    Electrons are, by definition, a fundamental, chemical and electromagnetic constituent of any plasma. This is especially true within the partially ionized plasmas of Earth's ionosphere where electrons are a critical component of a vast array of plasma processes. Siena College is working on a novel method of processing information from electron spectrometer anodes using delay line techniques and inexpensive COTS electronics to track the movement of high-energy particles. Electron spectrometers use a variety of techniques to determine where an amplified electron cloud falls onto a collecting surface. One traditional method divides the collecting surface into sectors and uses a single detector for each sector. However, as the angular and spatial resolution increases, so does the number of detectors, increasing power consumption, cost, size, and weight of the system. An alternative approach is to connect each sector with a delay line built within the PCB material which is shielded from cross talk by a flooded ground plane. Only one pair of detectors (e.g., one at each end of the chain) are needed with the delay line technique which is different from traditional delay line detectors which use either Application Specific Integrated Circuits (ASICs) or very fast clocks. In this paper, we report on the implementation and testing of a delay line detector using a low-cost Xilinx FPGA and a thirty-two sector delay system. This Delay Line Detector has potential satellite and rocket flight applications due to its low cost, small size and power efficiency

  12. Detecting larval export from marine reserves.

    Science.gov (United States)

    Pelc, R A; Warner, R R; Gaines, S D; Paris, C B

    2010-10-26

    Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves.

  13. Ultra-early Detection of Microcirculatory Injury as Predictor of Developing Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage.

    Science.gov (United States)

    Gölitz, Philipp; Hoelter, Philip; Rösch, Julie; Roessler, Karl; Knossalla, Frauke; Doerfler, Arnd

    2017-08-15

    Delayed cerebral ischemia (DCI) still remains a major complication after subarachnoid hemorrhage (SAH). The aim of our study was to evaluate whether flow analysis of admission digital subtraction angiography (DSA) using parametric color coding (PCC), a postprocessing algorithm, allows ultra-early identification of SAH patients at risk for developing subsequent symptomatic vasospasm. In this study 52 patients who suffered SAH from aneurysm rupture, were retrospectively enrolled. Of the patients 26 developed DCI and angiographically proven cerebral vasospasm and 26 age, gender-and clinical status-matched SAH patients without DCI served as controls. Using PCC, the following flow parameters were calculated: cerebral circulation time (CirT), cortical relative time to peak (rTTP) and microvascular transit time (TT). Mean cerebral CirT and cortical rTTP were longer in the DCI group (6.42 s ± 1.54 and 3.16 s ± 0.86, respectively) than in the non-DCI group (5.77 s ± 1.86 and 3.11 s ± 1.41, respectively), but without statistical significance. The mean microvascular TT was statistically significantly (p = 0.04) longer in the DCI group (3.19 s ± 0.78) than in the non-DCI group (2.67 s ± 0.73). Angiographic flow analysis might be suitable for ultra-early detection and quantitative assessment of microcirculatory injury in SAH patients, predictive of developing subsequent DCI. Prolonged microvascular TT seems to be a significant independent factor positively associated with DCI development. Identifying SAH patients at risk for DCI ultra-early after ictus might contribute to initiate prophylactic therapies before clinical deterioration.

  14. Functional evolution of Ets in echinoderms with focus on the evolution of echinoderm larval skeletons.

    Science.gov (United States)

    Koga, Hiroyuki; Matsubara, Mioko; Fujitani, Haruka; Miyamoto, Norio; Komatsu, Miéko; Kiyomoto, Masato; Akasaka, Koji; Wada, Hiroshi

    2010-09-01

    Convergent evolution of echinoderm pluteus larva was examined from the standpoint of functional evolution of a transcription factor Ets1/2. In sea urchins, Ets1/2 plays a central role in the differentiation of larval skeletogenic mesenchyme cells. In addition, Ets1/2 is suggested to be involved in adult skeletogenesis. Conversely, in starfish, although no skeletogenic cells differentiate during larval development, Ets1/2 is also expressed in the larval mesoderm. Here, we confirmed that the starfish Ets1/2 is indispensable for the differentiation of the larval mesoderm. This result led us to assume that, in the common ancestors of echinoderms, Ets1/2 activates the transcription of distinct gene sets, one for the differentiation of the larval mesoderm and the other for the development of the adult skeleton. Thus, the acquisition of the larval skeleton involved target switching of Ets1/2. Specifically, in the sea urchin lineage, Ets1/2 activated a downstream target gene set for skeletogenesis during larval development in addition to a mesoderm target set. We examined whether this heterochronic activation of the skeletogenic target set was achieved by the molecular evolution of the Ets1/2 transcription factor itself. We tested whether starfish Ets1/2 induced skeletogenesis when injected into sea urchin eggs. We found that, in addition to ectopic induction of mesenchyme cells, starfish Ets1/2 can activate some parts of the skeletogenic pathway in these mesenchyme cells. Thus, we suggest that the nature of the transcription factor Ets1/2 did not change, but rather that some unidentified co-factor(s) for Ets1/2 may distinguish between targets for the larval mesoderm and for skeletogenesis. Identification of the co-factor(s) will be key to understanding the molecular evolution underlying the evolution of the pluteus larvae.

  15. The influence of larval competition on Brazilian Wolbachia-infected Aedes aegypti mosquitoes.

    Science.gov (United States)

    Dutra, Heverton Leandro Carneiro; Lopes da Silva, Vanessa; da Rocha Fernandes, Mariana; Logullo, Carlos; Maciel-de-Freitas, Rafael; Moreira, Luciano Andrade

    2016-05-16

    With field releases starting in Brazil, particular interest must be given to understanding how the endosymbiotic bacterium Wolbachia pipientis affects Aedes aegypti mosquitoes with a Brazilian genetic background. Currently, there is limited information on how the bacterium affects phenotypic traits such as larval development rate, metabolic reserves and morphometric parameters in Ae. aegypti. Here, we analyze for the first time, the effect of Wolbachia on these key phenotypes and consider how this might impact the potential of the bacterium as a disease control agent in Brazil. We examined the influence of the wMel strain of Wolbachia in laboratory Ae. aegypti with a Brazilian genetic background, reared under different larval densities. Pupae formation was counted daily to assess differences in development rates. Levels of metabolic reserves and morphometric parameters were assessed in adults resulting from each larval condition. wMel infection led to more rapid larval development at higher densities for both males and females, with no effect under less crowded conditions in females. Infection also led to reduced body size at both high and low density, but not at intermediate density, although the scale of this difference was maintained regardless of larval density, in comparison to uninfected individuals. Wing shape also varied significantly between infected and uninfected mosquitoes due to larval density. Glycogen levels in uninfected mosquitoes decreased under higher larval density, but were consistently high with Wolbachia infection, regardless of larval density. We demonstrate that the wMel Wolbachia strain can positively influence some important host fitness traits, and that this interaction is directly linked to the conditions in which the host is reared. Combined with previously published data, these results suggest that this Wolbachia strain could be successfully used as part of the Eliminate Dengue Program in Brazil.

  16. Desenvolvimento larvário de Balanídeos em laboratório - Balanus amphitrite (Var. amphitrite Larval development of Balanids reared in laboratory: Balanus amphitrite var. amphitrite

    Directory of Open Access Journals (Sweden)

    Dyrce Lacombe

    1972-01-01

    laboratory. From the 200 Nauplii that we obtained from the lamellae we get 120 Cypris stages, and the growth of 78 young balanids. Cyclotella nana from the New York Aquarium culture was used for alimentation. The larval phase of Balanus amphitrite amphitrite consiste of six naupliar stages and one Cypris stage. Form and size of the body, the number and structure of the appendage settation and spines, are given for all the larval stages. There are described all details of the microanatomy of each stage. The setation is, however, a valuable criterion for the identification of the Nauplii and may be used to separate stages and species. The duration of the six stages are the followings; first stage: 15 to 20 minutes; second stage: from the 2th to 4th day; third stage; from the 4th day to 6th; fourth stage: up to 8th day; fifth stage: from the 9th to 11th day and the sixth stage: up to the 12th day. The necessary time for the complete larval development in laboratory of Balanus amphitrite amphitrite ranges from 12 to 14 days. We continued to observe and study the Cypris stages metamorphose in young balanids and their growth for more than 3 months in the glass criation.

  17. Effects of extra-embryonic provisioning on larval morphology and histogenesis in Boccardia proboscidea (Annelida, Spionidae).

    Science.gov (United States)

    Gibson, Glenys; Carver, David

    2013-01-01

    Morphology is strongly correlated with trophic mode in marine invertebrate larvae. We asked if larval morphogenesis is influenced by adelphophagy, a trophic mode in which larvae are provisioned with additional yolk in the form of extra-embryonic nurse eggs, instead of the more common increase in egg size. We used histology and scanning electron microscopy to analyze morphogenesis in Boccardia proboscidea, a polychaete that produces both small planktotrophic larvae and large adelphophagic larvae in a single egg capsule. Results indicate that both morphs are similar for histogenesis of ectodermal derivatives, and differ for the gut mucosa and coelom which show delayed differentiation in the adelphophagic morph. Heterochrony in gut and coelom development suggests that differentiation of these organ systems is decoupled from overall development, and that a trade-off exists between maturation of these tissues and rapid growth. We also looked for potential barriers to adelphophagy in planktotrophic larvae that have nurse eggs available to them. These planktotrophic larvae appeared morphologically equipped for adelphophagy: the gut was differentiated at an early stage, and larvae had structures involved in nurse-egg ingestion in the adelphophagic morph (e.g., oral cilia and ventral ciliated patches). Planktotrophic larvae were additionally capable of ingesting particles (Di-I) while in the egg capsule. Lack of adelphophagy in planktotrophic larvae remains enigmatic but these results indicate that morphology alone does not account for the arrested development shown by these larvae.

  18. A Strategy to Delay the Development of Cisplatin Resistance by Maintaining a Certain Amount of Cisplatin-Sensitive Cells.

    Science.gov (United States)

    Duan, Guihua; Tang, Qianyuan; Yan, Hongli; Xie, Lijuan; Wang, Yun; Zheng, Xi Emily; Zhuge, Yuzheng; Shen, Shanshan; Zhang, Bin; Zhang, Xiaoqi; Wang, Jun; Wang, Wei; Zou, Xiaoping

    2017-03-27

    Cisplatin (ddp), which is commonly employed in the treatment of many advanced cancers, often results in initial therapeutic success; however, rapid progression of ddp-resistant cells remains the main reason for treatment failure. Facd with such a problem, we investigated the fitness differences between ddp-sensitive and ddp-resistant cell lines. We found that the growth of ddp-resistant cells was significantly slower than that of sensitive cells due to elevated ROS levels, which suggested that the ddp resistance mechanisms may have negative impacts on the growth of resistant cells. Furthermore, we observed that, when mixed with ddp-sensitive cells, ddp-resistant cells failed to compete, and the growth of ddp-resistant cells could therefore be suppressed by treatment in vivo. We propose a mathematical model parameterized based on in vivo experiments to describe the allometric growth of tumors consisting of two competing subclones. According to our model, a quantitative strategy with a variant drug-dosing interval is proposed to control tumor growth. Taking advantage of intratumoral competition, our strategy with appropriate dosing intervals could remarkably delay the development of ddp resistance and prolong overall survival. Maintaining a certain number of ddp-sensitive cells rather than eradicating the tumor with continuous treatment is feasible for future tumor treatment.

  19. Compact-device model development for the energy-delay analysis of magneto-electric magnetic tunnel junction structures

    Science.gov (United States)

    Sharma, N.; Bird, J. P.; Dowben, P. A.; Marshall, A.

    2016-06-01

    We discuss the application of a novel class of device, the magneto-electric magnetic tunnel junction (ME-MTJ) to realize a variety of computational functions, including majority logic and the XNOR/XOR gate. We also develop a compact model to describe the operation of these devices, which function by utilizing the phenomenon of ‘voltage-controlled magnetism’ to switch the operational state of MTJs. The model breaks down the switching process into three key stages of operation: electrical-to-magnetic conversion, magnetization transfer, and final-state readout. Estimates for the switching energy and delay of these devices, obtained from this compact model, reveal significant improvements in both of these parameters when compared to conventional MTJs switched by spin-transfer-torque. In fact, the capacity to use the ME-MTJ to implement complex logical operations within a single device allows its energy costs to even approach those of low-power CMOS. The added benefits of non-volatility and compact circuit footprint, combined with their potential for heterogeneous integration with CMOS, make the ME devices of considerable interest for post-CMOS technology.

  20. Isolation and culture of larval cells from C. elegans.

    Directory of Open Access Journals (Sweden)

    Sihui Zhang

    Full Text Available Cell culture is an essential tool to study cell function. In C. elegans the ability to isolate and culture cells has been limited to embryonically derived cells. However, cells or blastomeres isolated from mixed stage embryos terminally differentiate within 24 hours of culture, thus precluding post-embryonic stage cell culture. We have developed an efficient and technically simple method for large-scale isolation and primary culture of larval-stage cells. We have optimized the treatment to maximize cell number and minimize cell death for each of the four larval stages. We obtained up to 7.8×10(4 cells per microliter of packed larvae, and up to 97% of adherent cells isolated by this method were viable for at least 16 hours. Cultured larval cells showed stage-specific increases in both cell size and multinuclearity and expressed lineage- and cell type-specific reporters. The majority (81% of larval cells isolated by our method were muscle cells that exhibited stage-specific phenotypes. L1 muscle cells developed 1 to 2 wide cytoplasmic processes, while L4 muscle cells developed 4 to 14 processes of various thicknesses. L4 muscle cells developed bands of myosin heavy chain A thick filaments at the cell center and spontaneously contracted ex vivo. Neurons constituted less than 10% of the isolated cells and the majority of neurons developed one or more long, microtubule-rich protrusions that terminated in actin-rich growth cones. In addition to cells such as muscle and neuron that are high abundance in vivo, we were also able to isolate M-lineage cells that constitute less than 0.2% of cells in vivo. Our novel method of cell isolation extends C. elegans cell culture to larval developmental stages, and allows use of the wealth of cell culture tools, such as cell sorting, electrophysiology, co-culture, and high-resolution imaging of subcellular dynamics, in investigation of post-embryonic development and physiology.

  1. 17-Beta estradiol and 4-nonylphenol delay smolt development and downstream migration in Atlantic salmon, Salmo salar.

    Science.gov (United States)

    Madsen, Steffen S; Skovbølling, Søren; Nielsen, Christian; Korsgaard, Bodil

    2004-06-10

    ) may contribute to the differential mortality. The study indicates that short-term exposure to natural and environmental estrogens may impair smolt development and survival and delay subsequent downstream migration in Atlantic salmon.

  2. A subset of interneurons required for Drosophila larval locomotion.

    Science.gov (United States)

    Yoshikawa, Shingo; Long, Hong; Thomas, John B

    2016-01-01

    Efforts to define the neural circuits generating locomotor behavior have produced an initial understanding of some of the components within the spinal cord, as well as a basic understanding of several invertebrate motor pattern generators. However, how these circuits are assembled during development is poorly understood. We are defining the neural circuit that generates larval locomotion in the genetically tractable fruit fly Drosophila melanogaster to study locomotor circuit development. Forward larval locomotion involves a stereotyped posterior-to-anterior segmental translocation of body wall muscle contraction and is generated by a relatively small number of identified muscles, motor and sensory neurons, plus an unknown number of the ~270 bilaterally-paired interneurons per segment of the 1st instar larva. To begin identifying the relevant interneurons, we have conditionally inactivated synaptic transmission of interneuron subsets and assayed for the effects on locomotion. From this screen we have identified a subset of 25 interneurons per hemisegment, called the lateral locomotor neurons (LLNs), that are required for locomotion. Both inactivation and constitutive activation of the LLNs disrupt locomotion, indicating that patterned output of the LLNs is required. By expressing a calcium indicator in the LLNs, we found that they display a posterior-to-anterior wave of activity within the CNS corresponding to the segmental translocation of the muscle contraction wave. Identification of the LLNs represents the first step toward elucidating the circuit generating larval locomotion.

  3. Metacommunity patterns in larval odonates.

    Science.gov (United States)

    McCauley, Shannon J; Davis, Christopher J; Relyea, Rick A; Yurewicz, Kerry L; Skelly, David K; Werner, Earl E

    2008-11-01

    The growth of metacommunity ecology as a subdiscipline has increased interest in how processes at different spatial scales structure communities. However, there is still a significant knowledge gap with respect to relating the action of niche- and dispersal-assembly mechanisms to observed species distributions across gradients. Surveys of the larval dragonfly community (Odonata: Anisoptera) in 57 lakes and ponds in southeast Michigan were used to evaluate hypotheses about the processes regulating community structure in this system. We considered the roles of both niche- and dispersal-assembly processes in determining patterns of species richness and composition across a habitat gradient involving changes in the extent of habitat permanence, canopy cover, area, and top predator type. We compared observed richness patterns and species distributions in this system to patterns predicted by four general community models: species sorting related to adaptive trade-offs, a developmental constraints hypothesis, dispersal assembly, and a neutral community assemblage. Our results supported neither the developmental constraints nor the neutral-assemblage models. Observed patterns of richness and species distributions were consistent with patterns expected when adaptive tradeoffs and dispersal-assembly mechanisms affect community structure. Adaptive trade-offs appeared to be important in limiting the distributions of species which segregate across the habitat gradient. However, dispersal was important in shaping the distributions of species that utilize habitats with a broad range of hydroperiods and alternative top predator types. Our results also suggest that the relative importance of these mechanisms may change across this habitat gradient and that a metacommunity perspective which incorporates both niche- and dispersal-assembly processes is necessary to understand how communities are organized.

  4. A Novel Microdeletion in 1(p34.2p34.3), Involving the "SLC2A1" ("GLUT1") Gene, and Severe Delayed Development

    Science.gov (United States)

    Vermeer, Sascha; Koolen, David A; Visser, Gepke; Brackel, Hein J. L.; van der Burgt, Ineke; de Leeuw, Nicole; Willemsen, Michel A. A. P.; Sistermans, Erik A.; Pfundt, Rolph; de Vries, Bert B. A.

    2007-01-01

    A "de novo" 4.1-megabase microdeletion of chromosome 1p34.2p34.3 has been identified by array-based comparative genomic hybridization in a young male with severely delayed development, microcephaly, pronounced hypotonia, and facial dysmorphism. The deleted region encompasses 48 genes, among them the glucose transporter 1 ("SLC2A1" or "GLUT1")…

  5. A novel microdeletion in 1(p34.2p34.3), involving the SLC2A1 (GLUT1) gene, and severe delayed development.

    NARCIS (Netherlands)

    Vermeer, S.; Koolen, D.A.; Visser, G.; Brackel, H.J.; Burgt, I. van der; Leeuw, N. de; Willemsen, M.A.A.P.; Sistermans, E.A.; Pfundt, R.; Vries, B.B. van

    2007-01-01

    A de novo 4.1-megabase microdeletion of chromosome 1p34.2p34.3 has been identified by array-based comparative genomic hybridization in a young male with severely delayed development, microcephaly, pronounced hypotonia, and facial dysmorphism. The deleted region encompasses 48 genes, among them the g

  6. A Novel Microdeletion in 1(p34.2p34.3), Involving the "SLC2A1" ("GLUT1") Gene, and Severe Delayed Development

    Science.gov (United States)

    Vermeer, Sascha; Koolen, David A; Visser, Gepke; Brackel, Hein J. L.; van der Burgt, Ineke; de Leeuw, Nicole; Willemsen, Michel A. A. P.; Sistermans, Erik A.; Pfundt, Rolph; de Vries, Bert B. A.

    2007-01-01

    A "de novo" 4.1-megabase microdeletion of chromosome 1p34.2p34.3 has been identified by array-based comparative genomic hybridization in a young male with severely delayed development, microcephaly, pronounced hypotonia, and facial dysmorphism. The deleted region encompasses 48 genes, among them the glucose transporter 1 ("SLC2A1" or "GLUT1")…

  7. 太平洋鳕仔鱼消化系统发育形态学和组织学观察%Ontogenetic morphological and histological development of digestive system in larval Pacific cod Gadus macrocephalus

    Institute of Scientific and Technical Information of China (English)

    胡盼; 宫雪; 韩雨哲; 姜志强; 潘金露

    2015-01-01

    The morphological and histological development of digestive system was observed in larval Pacific cod Gadus macrocephalus from 1 to 50 days post hatching ( DPH) under a light microscope. No differentiation in the di-gestive system was found at hatching, the mouth and anus were not opened, and liver and pancreas were appeared. The mouth gape was formed at 3 DPH and the intestine began to be differentiated. At 6 DPH, the digestive tract was consisted of buccopharynx, oesophagus, stomach anlage, intestine and rectum, with movable premaxilla and maxilla, with initial feeding capacity. The yolk sac was depleted completely at 12 DPH, and the intestine folds and mucus cells increased progressively in number, with almost complete digestive system and onset of exogenous nutri-tion. The intestine was spiral in shape, and the digestive organs and associated glands became further development steadily, similar to that in adult Pacific cod at 47 DPH. The findings provide a theoretical basis for the scientific management and nutrition for Pacific cod larva rearing.%采用切片技术和光学显微镜对1~50日龄太平洋鳕Gadus macrocephalus仔鱼的消化系统进行组织学和形态学观察。结果表明:初孵仔鱼消化系统基本没有分化,口和肛门尚未与外界相通,可见肝脏和胰脏;3日龄时,口裂形成,肠道开始分化;6日龄时,消化道已经分化出口咽腔、食道、胃前体、肠和直肠,上下颌可张合,初步具备摄食能力;12日龄时,卵黄囊完全消失,肠道皱褶和黏液细胞数量逐渐增多,消化系统逐渐发育完成,营外源性营养;仔鱼发育至47日龄时,肠道呈螺旋状,消化器官和消化腺趋于完善,接近成鱼。本研究可为太平洋鳕苗种的科学管理和营养饲料学方面的深入研究提供理论依据。

  8. Delayed development and lifespan extension as features of metabolic lifestyle alteration in C. elegans under dietary restriction.

    Science.gov (United States)

    Szewczyk, Nathaniel J; Udranszky, Ingrid A; Kozak, Elena; Sunga, June; Kim, Stuart K; Jacobson, Lewis A; Conley, Catharine A

    2006-10-01

    Studies of the model organism Caenorhabditis elegans have almost exclusively utilized growth on a bacterial diet. Such culturing presents a challenge to automation of experimentation and introduces bacterial metabolism as a secondary concern in drug and environmental toxicology studies. Axenic cultivation of C. elegans can avoid these problems, yet past work suggests that axenic growth is unhealthy for C. elegans. Here we employ a chemically defined liquid medium to culture C. elegans and find development slows, fecundity declines, lifespan increases, lipid and protein stores decrease, and gene expression changes relative to that on a bacterial diet. These changes do not appear to be random pathologies associated with malnutrition, as there are no developmental delays associated with starvation, such as L1 or dauer diapause. Additionally, development and reproductive period are fixed percentages of lifespan regardless of diet, suggesting that these alterations are adaptive. We propose that C. elegans can exist as a healthy animal with at least two distinct adult life histories. One life history maximizes the intrinsic rate of population increase, the other maximizes the efficiency of exploitation of the carrying capacity of the environment. Microarray analysis reveals increased transcript levels of daf-16 and downstream targets and past experiments demonstrate that DAF-16 (FOXO) acting on downstream targets can influence all of the phenotypes we see altered in maintenance medium. Thus, life history alteration in response to diet may be modulated by DAF-16. Our observations introduce a powerful system for automation of experimentation on healthy C. elegans and for systematic analysis of the profound impact of diet on animal physiology.

  9. Distribution, Health, and Development of Larval and Juvenile Lost River and Shortnose Suckers in the Williamson River Delta Restoration Project and Upper Klamath Lake, Oregon: 2008 Annual Data Summary

    Science.gov (United States)

    Burdick, Summer M.; Ottinger, Christopher; Brown, Daniel T.; VanderKooi, Scott P.; Robertson, Laura; Iwanowicz, Deborah

    2009-01-01

    Federally endangered Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris were once abundant throughout their range but populations have declined; they have been extirpated from several lakes, and may no longer reproduce in others. Poor recruitment into the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species, and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable rearing habitat. Within Upper Klamath Lake, a lack of marshes also may allow larval suckers to be swept from suitable rearing areas downstream into the seasonally anoxic waters of the Keno Reservoir. The Nature Conservancy (TNC) flooded about 3,600 acres to the north of the Williamson River mouth (Tulana Unit) in October 2007, and about 1,400 acres to the south and east of the Williamson River mouth (Goose Bay Unit) a year later, to retain larval suckers in Upper Klamath Lake, create nursery habitat for suckers, and improve water quality. In collaboration with TNC, the Bureau of Reclamation, and Oregon State University, we began a long-term collaborative research and monitoring program in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. Our approach includes two equally important aspects. One component is to describe habitat use and colonization processes by larval and juvenile suckers and non-sucker fish species. The second is to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report contains a summary of the first year of data collected as a part of this monitoring effort.

  10. Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis

    Science.gov (United States)

    Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval develop...

  11. Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis

    Science.gov (United States)

    Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval develop...

  12. Managing Ammonia Emissions From Screwworm Larval Rearing Media.

    Science.gov (United States)

    Sagel, Agustin; Phillips, Pamela; Chaudhury, Muhammad; Skoda, Steven

    2016-02-01

    Mass production, sterilization, and release of screwworms (Cochliomyia hominivorax (Coquerel)) that were competitive in the field significantly contributed to the successful application of the sterile insect technique for eradication of screwworms from continental North America. Metabolic byproducts resulting from protein-rich diets required for larval screwworms lead to ammonia liberation, sometimes at high levels, within the mass rearing facility. Until recently a sodium polyacrylate gel bulking agent was used for the larval media and adsorbed much of the ammonia. A need to replace the gel with an environmentally "friendly" bulking agent, while not increasing ammonia levels in the rearing facility, led to a series of experiments with the objective of developing procedures to reduce ammonia emissions from the larval media bulked with cellulose fiber. Additives of ammonia-converting bacteria, potassium permanganate, and Yucca schidigera Roezl ex Otrgies powder extract, previously reported to reduce ammonia levels in organic environments, were evaluated. Ammonia-converting bacteria did not have a positive effect. Addition of Y. schidigera powder extract (∼1% of total volume), potassium permanganate (∼250 ppm), and a combination of these two additives (at these same concentrations) kept ammonia at equivalent levels as when larval media was bulked with gel. Potassium permanganate also had sufficient antimicrobial properties that the use of formaldehyde in the diet was not necessary. Further testing is needed, at a mass rearing level, before full implementation into the screwworm eradication program. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

  13. 全数字延时锁定环的研究进展%Research Development of All Digital Delay-locked Loops

    Institute of Scientific and Technical Information of China (English)

    徐太龙; 陈军宁; 孟坚; 徐超; 柯导明

    2013-01-01

    全数字延时锁定环在现代超大规模系统芯片中具有极其重要的作用,被广泛地用于解决系统时钟的产生和分布问题,因此详细分析其研究进展具有一定的理论意义和实际应用价值.首先在分析延时锁定环工作原理的基础上,阐明了全数字延时锁定环相对于全模拟和混合信号延时锁定环具有的优点.其次详细阐述了全数字延时锁定环的发展过程、研究现状和存在的问题,尤其在指出传统逐次逼近寄存器延时锁定环存在谐波锁定、锁定时间没有达到理论值和死锁三个问题的基础上,对各种改进型逐次逼近寄存器延时锁定环的性能进行了对比分析.最后对全数字延时锁定环的未来发展趋势进行了展望.%All digital delay-locked loops play a very important role in modern day very large scale integrated system-on-chips for widely used to solve the problems of generation and distribution of the system clocks,so analyzing its research development has theoretical and actual application sense.Based on analyzing the operation principle of the delay-locked loops,the advantages of the all digital delay-locked loops are presented,compared to the all analog and mixed-signal delay-locked loops.The developing process,research starus and current problems of all digital delay-locked loops are described in detail,especially,the three issues of harmonic-locking,lock-time longer than theoretical value and dead-lock of the conventional all digital delay-locked loops are pointed out,and then the performances of various improved all digital delay-locked loops are compared.Finally the future development trends of all digital delay-locked loops are pointed out.

  14. Oceanography promotes self-recruitment in a planktonic larval disperser

    Science.gov (United States)

    Teske, Peter R.; Sandoval-Castillo, Jonathan; van Sebille, Erik; Waters, Jonathan; Beheregaray, Luciano B.

    2016-01-01

    The application of high-resolution genetic data has revealed that oceanographic connectivity in marine species with planktonic larvae can be surprisingly limited, even in the absence of major barriers to dispersal. Australia’s southern coast represents a particularly interesting system for studying planktonic larval dispersal, as the hydrodynamic regime of the wide continental shelf has potential to facilitate onshore retention of larvae. We used a seascape genetics approach (the joint analysis of genetic data and oceanographic connectivity simulations) to assess population genetic structure and self-recruitment in a broadcast-spawning marine gastropod that exists as a single meta-population throughout its temperate Australian range. Levels of self-recruitment were surprisingly high, and oceanographic connectivity simulations indicated that this was a result of low-velocity nearshore currents promoting the retention of planktonic larvae in the vicinity of natal sites. Even though the model applied here is comparatively simple and assumes that the dispersal of planktonic larvae is passive, we find that oceanography alone is sufficient to explain the high levels of genetic structure and self-recruitment. Our study contributes to growing evidence that sophisticated larval behaviour is not a prerequisite for larval retention in the nearshore region in planktonic-developing species. PMID:27687507

  15. Oceanography promotes self-recruitment in a planktonic larval disperser.

    Science.gov (United States)

    Teske, Peter R; Sandoval-Castillo, Jonathan; van Sebille, Erik; Waters, Jonathan; Beheregaray, Luciano B

    2016-09-30

    The application of high-resolution genetic data has revealed that oceanographic connectivity in marine species with planktonic larvae can be surprisingly limited, even in the absence of major barriers to dispersal. Australia's southern coast represents a particularly interesting system for studying planktonic larval dispersal, as the hydrodynamic regime of the wide continental shelf has potential to facilitate onshore retention of larvae. We used a seascape genetics approach (the joint analysis of genetic data and oceanographic connectivity simulations) to assess population genetic structure and self-recruitment in a broadcast-spawning marine gastropod that exists as a single meta-population throughout its temperate Australian range. Levels of self-recruitment were surprisingly high, and oceanographic connectivity simulations indicated that this was a result of low-velocity nearshore currents promoting the retention of planktonic larvae in the vicinity of natal sites. Even though the model applied here is comparatively simple and assumes that the dispersal of planktonic larvae is passive, we find that oceanography alone is sufficient to explain the high levels of genetic structure and self-recruitment. Our study contributes to growing evidence that sophisticated larval behaviour is not a prerequisite for larval retention in the nearshore region in planktonic-developing species.

  16. Green tea proanthocyanidins cause impairment of hormone-regulated larval development and reproductive fitness via repression of juvenile hormone acid methyltransferase, insulin-like peptide and cytochrome P450 genes in Anopheles gambiae sensu stricto

    Science.gov (United States)

    Nyanjom, Steven G.; Mutunga, James M.; Njeru, Sospeter N.; Bargul, Joel L.

    2017-01-01

    Successful optimization of plant-derived compounds into control of nuisance insects would benefit from scientifically validated targets. However, the close association between the genotypic responses and physiological toxicity effects mediated by these compounds remains underexplored. In this study, we evaluated the sublethal dose effects of proanthocyanidins (PAs) sourced from green tea (Camellia sinensis) on life history traits of Anopheles gambiae (sensu stricto) mosquitoes with an aim to unravel the probable molecular targets. Based on the induced phenotypic effects, genes selected for study targeted juvenile hormone (JH) biosynthesis, signal transduction, oxidative stress response and xenobiotic detoxification in addition to vitellogenesis in females. Our findings suggest that chronic exposure of larval stages (L3/L4) to sublethal dose of 5 ppm dramatically extended larval developmental period for up to 12 days, slowed down pupation rates, induced abnormal larval-pupal intermediates and caused 100% inhibition of adult emergence. Further, females exhibited significant interference of fecundity and egg hatchability relative to controls (p reproductive fitness thus could be potentially used for controlling populations of malaria vectors. PMID:28301607

  17. Language development, delay and intervention-the views of parents from communities that speech and language therapy managers in England consider to be under-served.

    Science.gov (United States)

    Marshall, Julie; Harding, Sam; Roulstone, Sue

    2017-07-01

    Evidence-based practice includes research evidence, clinical expertise and stakeholder perspectives. Stakeholder perspectives are important and include parental ethno-theories, which embrace views about many aspects of speech, language and communication, language development, and interventions. The Developmental Niche Framework provides a useful theory to understand parental beliefs. Ethnotheories, including those about language development, delay and interventions, may vary cross culturally and are less well understood in relation to families who may be considered 'under-served' or 'hard-to-reach' by speech and language therapy services. Who is considered to be under-served and the reasons why some families are under-served are complex. To describe beliefs and reported practices, in relation to speech and language development, delay and intervention, of parents and carers from a small number of groups in England who were perceived to be under-served in relation to SLT services. As part of a wider National Institute for Health Research (NIHR)-funded study (Child Talk), seven focus groups (with a total of 52 participants) were held with parents from three communities in England. Topics addressed included beliefs about language development, language delay and parents' reported responses to language delay. Data were transcribed and analysed using adapted framework analysis, which also drew on directed content analysis. Four themes resulted that broadly matched the topics addressed in the focus groups: language development and the environment; causes and signs of speech and language delay; responses to concerns about speech, language and communication; and improving SLT. These produced some previously unreported ideas, e.g., about how language develops and the causes of delay. The findings are discussed in relation to previous literature and the Developmental Niche Framework. Clinical implications include ideas about issues for SLTs to discuss with families and the

  18. Intellectual development analysis of delayed language development in 150 children%150例语言发育迟缓儿童的智能发育分析

    Institute of Scientific and Technical Information of China (English)

    徐志兵

    2014-01-01

    Objective To investigate the intellectual development of delayed language development children. Methods The study included 150 children of delayed language development,who were divided into three groups in accordance with the extent of language development defect,78 cases of mild defects,59 cases of moderate defects,13 cases of severe defects. Results The language,adaptive behavior and personal social scores reduced in turn in the mild defects,moder-ate defects,severe defects group,there were statistically significant difference (P<0.05).Language development and adap-tive behavior,fine motor and personal social development levels had significantly positive correlation (P<0.05).The inci-dence of adaptive behavior and low personal social in the mild defects,moderate defects,severe defects group increased in turn,there were statistically significant difference (P<0.05). Conclusion On the assessment of the level of intellectual development,adaptive behavior,fine motor and personal social training should be joined the language training of delayed language development children.%目的:探讨语言发育迟缓儿童的智能发育。方法本次研究对象共包括150例语言发育迟缓儿童,按照语言发育的缺陷程度分为3组,其中轻度缺陷78例,中度缺陷59例,重度缺陷13例。结果轻度缺陷、中度缺陷、重度缺陷组患儿的语言、适应行为、个人社交得分均依次降低,3组差异有统计学意义(P<0.05)。语言发育水平与适应行为、精细动作及个人社交发育水平呈明显正相关性(P<0.05)。轻度缺陷、中度缺陷及重度缺陷组的适应行为、个人社交低下的发生率呈依次升高趋势,3组差异有统计学意义(P<0.05)。结论在对智能发育水平进行评估的同时,应将适应行为、精细运动及个人社交方面的训练加入语言发育迟缓儿童语言训练中。

  19. Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus.

    Science.gov (United States)

    Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E; Muturi, Ephantus J

    2015-01-01

    Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced.

  20. Exposure to 2,4-decadienal negatively impacts upon marine invertebrate larval fitness.

    Science.gov (United States)

    Caldwell, Gary S; Lewis, Ceri; Olive, Peter J W; Bentley, Matthew G

    2005-06-01

    Diatoms liberate volatile, biologically active unsaturated aldehydes following cell damage, which negatively impact upon invertebrate reproductive processes such as fertilization, embryogenesis and larval survival. 2,4-Decadienal is frequently identified among the aldehydes produced and is one of the more biologically active. The majority of studies which have examined the toxic effects of diatom aldehydes to invertebrate reproduction have scored egg production and/or hatching success as indicators of biological impacts. There are very few studies which have dealt specifically with the impacts of diatom-derived aldehydes on larval fitness. Larval stages of the polychaetes Arenicola marina and Nereis virens and the echinoderms Asterias rubens and Psammechinus miliaris exposed to 2,4-decadienal at sub 1 microg ml(-1) concentrations suffered reduced survival over the incubation period (day 1-8 post fertilization) with detectable differences for the polychates at a concentration of 0.005 and 0.01-0.1 microg ml(-1) for the echinoderms. Susceptibility of larval N. virens was investigated using stage specific 24 h exposures at 2,4-decadienal concentrations up to 1.5 microg ml(-1). A clear stage specific effect was found, with earlier larval stages most vulnerable. Nectochaete larvae (9-10 d) showed no reduction in survival at the concentrations assayed. Fluctuating asymmetry (FA), defined as random deviations from perfect bilateral symmetry, was used to analyse fitness of larval P. miliaris exposed to 2,4-decadienal at concentrations of 0.1, 0.5 and 1 microg ml(-1). The degree and frequency of asymmetrical development increased with increasing 2,4-decadienal concentration. Equally, as FA increased larval survival decreased. These results provide further support for the teratogenic nature of 2,4-decadienal and its negative impact on invertebrate larval fitness.

  1. Factors affecting fungus-induced larval mortality in Anopheles gambiae and Anopheles stephensi

    Directory of Open Access Journals (Sweden)

    Takken Willem

    2010-01-01

    Full Text Available Abstract Background Entomopathogenic fungi have shown great potential for the control of adult malaria vectors. However, their ability to control aquatic stages of anopheline vectors remains largely unexplored. Therefore, how larval characteristics (Anopheles species, age and larval density, fungus (species and concentration and environmental effects (exposure duration and food availability influence larval mortality caused by fungus, was studied. Methods Laboratory bioassays were performed on the larval stages of Anopheles gambiae and Anopheles stephensi with spores of two fungus species, Metarhizium anisopliae and Beauveria bassiana. For various larval and fungal characteristics and environmental effects the time to death was determined and survival curves established. These curves were compared by Kaplan Meier and Cox regression analyses. Results Beauveria bassiana and Metarhizium anisopliae caused high mortality of An. gambiae and An. stephensi larvae. However, Beauveria bassiana was less effective (Hazard ratio (HR Metarhizium anisopliae. Anopheles stephensi and An. gambiae were equally susceptible to each fungus. Older larvae were less likely to die than young larvae (HR Conclusions This study shows that both fungus species have potential to kill mosquitoes in the larval stage, and that mortality rate depends on fungus species itself, larval stage targeted, larval density and amount of nutrients available to the larvae. Increasing the concentration of fungal spores or reducing the exposure time to spores did not show a proportional increase and decrease in mortality rate, respectively, because the spores clumped together. As a result spores did not provide uniform coverage over space and time. It is, therefore, necessary to develop a formulation that allows the spores to spread over the water surface. Apart from formulation appropriate delivery methods are also necessary to avoid exposing non-target organisms to fungus.

  2. Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

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    Verschave, S H; Levecke, B; Duchateau, L; Vercruysse, J; Charlier, J

    2015-06-15

    component = 6.2), rather than due to pasture (variance component = 0.55) or season (variance component = 0.15). Using the observed distribution of L3, the required sample size (i.e. number of plots per pasture) for sampling a pasture through random plots with a particular precision was simulated. A higher relative precision was acquired when estimating PLC on pastures with a high larval contamination and a low level of aggregation compared to pastures with a low larval contamination when the same sample size was applied. In the future, herbage sampling through random plots across pasture (method 2) seems a promising method to develop further as no significant difference in counts between the methods was found and this method was less time consuming.

  3. Relative impacts of adult movement, larval dispersal and harvester movement on the effectiveness of reserve networks.

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    Grüss, Arnaud; Kaplan, David M; Hart, Deborah R

    2011-01-01

    Movement of individuals is a critical factor determining the effectiveness of reserve networks. Marine reserves have historically been used for the management of species that are sedentary as adults, and, therefore, larval dispersal has been a major focus of marine-reserve research. The push to use marine reserves for managing pelagic and demersal species poses significant questions regarding their utility for highly-mobile species. Here, a simple conceptual metapopulation model is developed to provide a rigorous comparison of the functioning of reserve networks for populations with different admixtures of larval dispersal and adult movement in a home range. We find that adult movement produces significantly lower persistence than larval dispersal, all other factors being equal. Furthermore, redistribution of harvest effort previously in reserves to remaining fished areas ('fishery squeeze') and fishing along reserve borders ('fishing-the-line') considerably reduce persistence and harvests for populations mobile as adults, while they only marginally changes results for populations with dispersing larvae. Our results also indicate that adult home-range movement and larval dispersal are not simply additive processes, but rather that populations possessing both modes of movement have lower persistence than equivalent populations having the same amount of 'total movement' (sum of larval and adult movement spatial scales) in either larval dispersal or adult movement alone.

  4. Larval density dependence in Anopheles gambiae s.s., the major African vector of malaria

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    Muriu, Simon M.; Coulson, Tim; Mbogo, Charles M.; Godfray, H. Charles J.

    2017-01-01

    Summary Anopheles gambiae sensu stricto is the most important vector of malaria in Africa although relatively little is known about the density-dependent processes determining its population size.Mosquito larval density was manipulated under semi-natural conditions using artificial larval breeding sites placed in the field in coastal Kenya; two experiments were conducted: one manipulating the density of a single cohort of larvae across a range of densities and the other employing fewer densities but with the treatments crossed with four treatments manipulating predator access.In the first experiment, larval survival, development rate and the size of the adult mosquito all decreased with larval density (controlling for block effects between 23% and 31% of the variance in the data could be explained by density).In the second experiment, the effects of predator manipulation were not significant, but again we observed strong density dependence in larval survival (explaining 30% of the variance).The results are compared with laboratory studies of A. gambiae larval competition and the few other studies conducted in the field, and the consequences for malaria control are discussed PMID:23163565

  5. Relative impacts of adult movement, larval dispersal and harvester movement on the effectiveness of reserve networks.

    Directory of Open Access Journals (Sweden)

    Arnaud Grüss

    Full Text Available Movement of individuals is a critical factor determining the effectiveness of reserve networks. Marine reserves have historically been used for the management of species that are sedentary as adults, and, therefore, larval dispersal has been a major focus of marine-reserve research. The push to use marine reserves for managing pelagic and demersal species poses significant questions regarding their utility for highly-mobile species. Here, a simple conceptual metapopulation model is developed to provide a rigorous comparison of the functioning of reserve networks for populations with different admixtures of larval dispersal and adult movement in a home range. We find that adult movement produces significantly lower persistence than larval dispersal, all other factors being equal. Furthermore, redistribution of harvest effort previously in reserves to remaining fished areas ('fishery squeeze' and fishing along reserve borders ('fishing-the-line' considerably reduce persistence and harvests for populations mobile as adults, while they only marginally changes results for populations with dispersing larvae. Our results also indicate that adult home-range movement and larval dispersal are not simply additive processes, but rather that populations possessing both modes of movement have lower persistence than equivalent populations having the same amount of 'total movement' (sum of larval and adult movement spatial scales in either larval dispersal or adult movement alone.

  6. Enhancement of larval RNAi efficiency by over-expressing Argonaute2 in Bombyx mori.

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    Li, Zhiqian; Zeng, Baosheng; Ling, Lin; Xu, Jun; You, Lang; Aslam, Abu F M; Tan, Anjiang; Huang, Yongping

    2015-01-01

    RNA interference has been described as a powerful genetic tool for gene functional analysis and a promising approach for pest management. However, RNAi efficiency varies significantly among insect species due to distinct RNAi machineries. Lepidopteran insects include a large number of pests as well as model insects, such as the silkworm, Bombyx mori. However, only limited success of in vivo RNAi has been reported in lepidoptera, particularly during the larval stages when the worms feed the most and do the most harm to the host plant. Enhancing the efficiency of larval RNAi in lepidoptera is urgently needed to develop RNAi-based pest management strategies. In the present study, we investigate the function of the conserved RNAi core factor, Argonaute2 (Ago2), in mediating B. mori RNAi efficiency. We demonstrate that introducing BmAgo2 dsRNA inhibits the RNAi response in both BmN cells and embryos. Furthermore, we establish several transgenic silkworm lines to assess the roles of BmAgo2 in larval RNAi. Over-expressing BmAgo2 significantly facilitated both dsRNA-mediated larval RNAi when targeting DsRed using dsRNA injection and shRNA-mediated larval RNAi when targeting BmBlos2 using transgenic shRNA expression. Our results show that BmAgo2 is involved in RNAi in B. mori and provides a promising approach for improving larval RNAi efficiency in B. mori and in lepidopteran insects in general.

  7. Shifty salamanders: transient trophic polymorphism and cannibalism within natural populations of larval ambystomatid salamanders.

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    Jefferson, Dale M; Ferrari, Maud Co; Mathis, Alicia; Hobson, Keith A; Britzke, Eric R; Crane, Adam L; Blaustein, Andrew R; Chivers, Douglas P

    2014-01-01

    Many species of ambystomatid salamanders are dependent upon highly variable temporary wetlands for larval development. High larval densities may prompt the expression of a distinct head morphology that may facilitate cannibalism. However, few studies have characterized struc