Infestation of natural populations of earthworm cocoons by rhabditid and cephalobid nematodes

DEFF Research Database (Denmark)

Kraglund, HO; Ekelund, Flemming

2002-01-01

Nematodes infested 13 of 100 earthworm cocoons from a compost pile and 17 of 197 cocoons from a permanent pasture soil. Between one and 2000 nematodes were found within the infested cocoons. All nematodes found in cocoons from the compost pile belonged to the genus Rhabditis, while Rhabditis spp....... as well as members of Cephalobidae infested earthworm cocoons in the pasture soil. In cultures established from cocoons found in the pasture soil, at least five different types of nematodes belonging to the family Cephalobidae were found. Acrobeloides nanus was found in six cocoons, Cephalobus persegnis...... was found in four and Chiloplacus minimus was found in one cocoon. We suggest that earthworm - nematode interactions may be an important pathway for the transfer of carbon in terrestrial ecosystems, and that the inclusion of these pathways may lead to a better understanding of soil food web functioning....

Naturally induced secretions of the potato cyst nematode co-stimulate the proliferation of both tobacco leaf protoplasts and human peripheral blood mononuclear cells.

Science.gov (United States)

Goverse, A; Rouppe van der Voort, J; Roppe van der Voort, C; Kavelaars, A; Smant, G; Schots, A; Bakker, J; Helder, J

1999-10-01

Naturally induced secretions from infective juveniles of the potato cyst nematode Globodera rostochiensis co-stimulate the proliferation of tobacco leaf protoplasts in the presence of the synthetic phytohormones alpha-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). With the use of a protoplast-based bioassay, a low-molecular-weight peptide(s) (cyst nematode secretions also co-stimulated mitogenesis in human peripheral blood mononuclear cells (PBMC). The stimulation of plant cells isolated from nontarget tissue--these nematodes normally invade the roots of potato plants--suggests the activation of a general signal transduction mechanism(s) by an oligopeptide(s) secreted by the nematode. Whether a similar oligopeptide-induced mechanism underlies human PBMC activation remains to be investigated. Reactivation of the cell cycle is a crucial event in feeding cell formation by cyst nematodes. The secretion of a mitogenic low-molecular-weight peptide(s) by infective juveniles of the potato cyst nematode could contribute to the redifferentiation of plant cells into such a feeding cell.

Natural infection of free-range chickens with the ascarid nematode Toxocara sp.

Science.gov (United States)

Campos-da-Silva, Danielle R; da Paz, Jeanne S; Fortunato, Viviane R; Beltrame, Marcus A V; Valli, Luis C P; Pereira, Fausto E L

2015-11-01

Human toxocariasis may be acquired by eating raw chicken liver. However, there are no reports on the prevalence of natural infection of chickens with Toxocara. The aim of this study was to evaluate the presence of anti-Toxocara antibodies as indicators of natural infection with Toxocara, in free-range chickens from Espírito Santo State, Brazil. An ELISA test with secretory and excretory Toxocara canis antigens was used. Negative controls were 20 industrial chickens reared in a high hygiene standard environment. Positive control serum was from a chicken infected with embryonated eggs of T. canis. Sera were adsorbed with Ascaridia galli extract to reduce cross-reactivity. Cut-off was the mean plus four times the standard deviation of optical density (OD) in negative group. One hundred and fifty-seven sera from free-range chicken were investigated. Results showed 58.5% of the chickens were positive with ELISA test; 12.7% had OD over the positive control and may be considered as true infected chickens. The results between the cut-off and the positive control may include infections with low titers of antibodies or may represent serum scar of past infection or may be the result of cross-reaction with other nematodes rather than A. galli which is used for the adsorption of sera. In conclusion, high prevalence of Toxocara sp. antibodies demonstrates natural infection of free-range chickens from Espírito Santo State which may represent a risk of infection with this nematode in people who have the habit of eating raw or undercooked chicken meat or viscera. The results also suggest that chickens may be useful as sentinels to detect soil contaminated with Toxocara eggs.

Naturally Occurring Radioactive Materials (NORM)

International Nuclear Information System (INIS)

Gray, P.

1997-01-01

This paper discusses the broad problems presented by Naturally Occuring Radioactive Materials (NORM). Technologically Enhanced naturally occuring radioactive material includes any radionuclides whose physical, chemical, radiological properties or radionuclide concentration have been altered from their natural state. With regard to NORM in particular, radioactive contamination is radioactive material in an undesired location. This is a concern in a range of industries: petroleum; uranium mining; phosphorus and phosphates; fertilizers; fossil fuels; forestry products; water treatment; metal mining and processing; geothermal energy. The author discusses in more detail the problem in the petroleum industry, including the isotopes of concern, the hazards they present, the contamination which they cause, ways to dispose of contaminated materials, and regulatory issues. He points out there are three key programs to reduce legal exposure and problems due to these contaminants: waste minimization; NORM assesment (surveys); NORM compliance (training)

Naturally Occurring Radioactive Materials (NORM)

Energy Technology Data Exchange (ETDEWEB)

Gray, P. [ed.

1997-02-01

This paper discusses the broad problems presented by Naturally Occuring Radioactive Materials (NORM). Technologically Enhanced naturally occuring radioactive material includes any radionuclides whose physical, chemical, radiological properties or radionuclide concentration have been altered from their natural state. With regard to NORM in particular, radioactive contamination is radioactive material in an undesired location. This is a concern in a range of industries: petroleum; uranium mining; phosphorus and phosphates; fertilizers; fossil fuels; forestry products; water treatment; metal mining and processing; geothermal energy. The author discusses in more detail the problem in the petroleum industry, including the isotopes of concern, the hazards they present, the contamination which they cause, ways to dispose of contaminated materials, and regulatory issues. He points out there are three key programs to reduce legal exposure and problems due to these contaminants: waste minimization; NORM assesment (surveys); NORM compliance (training).

Natural occurring radioactive substances. Vol. 1

Energy Technology Data Exchange (ETDEWEB)

Emara, A E [National Center for radiation Research and Technology Atomic Energy Authority, Cairo (Egypt)

1996-03-01

Naturally occurring radioactive substances produced by cosmic rays of those of terrestrial origin are surveyed. The different radioactive decay series are discussed. Special emphasis is given to the element radium as regards its properties and distribution in different environmental samples. The properties of naturally occurring k-40 and its distribution in different natural media are also outlined. Induced radionuclides which are formed as a result of the interaction of cosmic rays with the constituents of the atmosphere are mentioned. In this respect the intensity of natural background radiation and the dose at different locations and levels is surveyed. Some regions of exceptionally high radioactivity which result in high exposure rates are mentioned. Monazite deposits and water springs are mentioned in some detail. The Oklo phenomenon as a natural reactor is also discussed. 8 tabs.

Natural occurring radioactive substances. Vol. 1

International Nuclear Information System (INIS)

Emara, A.E.

1996-01-01

Naturally occurring radioactive substances produced by cosmic rays of those of terrestrial origin are surveyed. The different radioactive decay series are discussed. Special emphasis is given to the element radium as regards its properties and distribution in different environmental samples. The properties of naturally occurring k-40 and its distribution in different natural media are also outlined. Induced radionuclides which are formed as a result of the interaction of cosmic rays with the constituents of the atmosphere are mentioned. In this respect the intensity of natural background radiation and the dose at different locations and levels is surveyed. Some regions of exceptionally high radioactivity which result in high exposure rates are mentioned. Monazite deposits and water springs are mentioned in some detail. The Oklo phenomenon as a natural reactor is also discussed. 8 tabs

Determination of natural occurring radionuclides concentrations

International Nuclear Information System (INIS)

Stajic, J.; Markovic, V.; Krstic, D.; Nikezic, D.

2011-01-01

Tobacco smoke contains certain concentrations of naturally occurring radionuclides from radioactive chains of uranium and thorium - 214 Pb, 214 Bi, 228 Ac, 208 Tl, 226 Ra, 232 Th and 40 K. Inhaling of tobacco smoke leads to internal exposure of man. In order to estimate absorbed dose of irradiation it is necessary to determine concentrations of radionuclides present in the tobacco leaves. In this paper specific activities of naturally occurring radionuclides were measured in tobacco samples from cigarettes which are used in Serbia. [sr

Metabolic cues for puberty onset in free grazing Holstein heifers naturally infected with nematodes.

Science.gov (United States)

Díaz-Torga, G S; Mejia, M E; González-Iglesias, A; Formia, N; Becú-Villalobos, D; Lacau-Mengido, I M

2001-07-01

Leptin is a new plausible candidate for the molecular link between nutritional status and the reproductive axis. In previous studies we described that continuous natural nematode infections in heifers retarded growth and delayed the onset of puberty, and that the insulin-like growth factor I (IGF-I) was involved. In the present study we monitored the leptin levels during development in heifers naturally parasitized versus those chronically treated with ivermectin and we investigated whether growth hormone (GH) accounted for the differences in IGF-I previously noted. Insulin levels were also measured. Prolactin hormone was recorded as an indicator of immune system activation. We found a direct correlation between leptin and body weight during development and a prepubertal surge of the hormone 2 weeks before the first progesterone peak that indicates the onset of puberty. This suggests that leptin may act as a signal for this event. Insulin did not vary during growth and prepuberty. On the other hand, GH as not responsible for diminished IGF-I levels in parasitized animals as levels were similar in both groups. The GH levels were high at birth and then diminished rapidly and remained constant during development and puberty. The last hormone studied, prolactin, followed seasonal changes of sunlight duration and presented sporadic bursts in infected animals. These were related to high nematode infection and are probably involved in the immune response of the host.

Host suitability of soybean and corn genotypes to the root lesion caused by nematode under natural infestation conditions

Directory of Open Access Journals (Sweden)

Anderli Divina Ferreira Rios

2016-04-01

Full Text Available ABSTRACT: Among the nematode management strategies, genetic resistance is one of the most appropriate and desirable. However, resistant soybean and corn genotypes resistant to Pratylenchus brachyurus are not available up to the moment. The objective of this study was to evaluate the host suitability of 50 soybean and 38 corn genotypes to P. brachyurus under natural infestation. Soybean genotypes BRSGO Chapadões, BRSGO Paraíso, M-Soy 7211 RR, M-Soy 8008 RR, Emgopa 313 RR, M-Soy 8411, BRSGO Juliana RR, Emgopa 316 RR, BRSGO Luziânia RR and TMG 103 RR, and corn genotype Agromem 30A06 reduced the nematode population during the evaluation period.

Entomogenous nematode Neoaplectana carpocapsae: radiation and mammalian safety

International Nuclear Information System (INIS)

Gaugler, R.R.

1978-01-01

Infective-stage juveniles of Neoaplacetana carpocapsae were acutely sensitive to short uv radiation (254 nm) and natural sunlight. High nematode mortality, although delayed, accompanied uv exposure. Irradiation rapidly reduced nematode pathogenicity, so that nematodes exposed for 7 min were unable to cause lethal infections in Galleria mallonella larvae. Moreover, the median survival time of Galleria larvae increased progressively as nematode exposure to uv was lengthened. Inhibition of nematode reproduction and development was noted at exposure periods more than 2.45 and 5 min, respectively. However, irradiation did not appear to affect juvenile motility. Exposure to direct sunlight also reduced pathogenicity, in a range from 6.9 to 94.9% at 30 and 60 min of exposure, respectively. Long uv (366 nm) did not affect juveniles at the exposures tested

Management of Root-Nematode (Meloidogyne SPP)

International Nuclear Information System (INIS)

Miano, D.W

2002-01-01

Greenhouse and field experiments were undertaken to determine the possibility of using soil amendments with different C:N levels or applied at different rates and times in the control of root-knot nematodes (Meloidogyne spp.)in tomato c.v Cal J.A naturally infested field was used while artificial inoculation was done in the greenhouse. Root galling was rated on a scale of 0-10, nematode population was estimated by counting second stage juveniles extracted from 200 cm 3 soil and fruit yields were recorded at the end of the season. Nematode population densities and galling indices were significantly (P< or=0.05) lower in amended soils compared to the control. Application of the amendments also resulted in significant (P< or=0.05) increase in yields. Chicken manure, compost manure, neem products and pig manure were were the most effective amendments. Fresh chicken manure had a more suppressive effect on nematode than when the manure was decomposed within or outside a nematode infested field. A general decrease in juvenile populations and galling was observed with increase of organic amendments applied

Plant species richness sustains higher trophic levels of soil nematode communities after consecutive environmental perturbations.

Science.gov (United States)

Cesarz, Simone; Ciobanu, Marcel; Wright, Alexandra J; Ebeling, Anne; Vogel, Anja; Weisser, Wolfgang W; Eisenhauer, Nico

2017-07-01

The magnitude and frequency of extreme weather events are predicted to increase in the future due to ongoing climate change. In particular, floods and droughts resulting from climate change are thought to alter the ecosystem functions and stability. However, knowledge of the effects of these weather events on soil fauna is scarce, although they are key towards functioning of terrestrial ecosystems. Plant species richness has been shown to affect the stability of ecosystem functions and food webs. Here, we used the occurrence of a natural flood in a biodiversity grassland experiment that was followed by a simulated summer drought experiment, to investigate the interactive effects of plant species richness, a natural flood, and a subsequent summer drought on nematode communities. Three and five months after the natural flooding, effects of flooding severity were still detectable in the belowground system. We found that flooding severity decreased soil nematode food-web structure (loss of K-strategists) and the abundance of plant feeding nematodes. However, high plant species richness maintained higher diversity and abundance of higher trophic levels compared to monocultures throughout the flood. The subsequent summer drought seemed to be of lower importance but reversed negative flooding effects in some cases. This probably occurred because the studied grassland system is well adapted to drought, or because drought conditions alleviated the negative impact of long-term soil waterlogging. Using soil nematodes as indicator taxa, this study suggests that high plant species richness can maintain soil food web complexity after consecutive environmental perturbations.

Detecting genotypic variation among the single spore isolates of Pasteuria penetrans population occuring in Florida using SNP-based markers

Science.gov (United States)

Pasteuria penetrans is a naturally occurring soil-borne endospore-forming bacterium, which functions as a castrating parasite of plant-parasitic nematodes belonging to the genus Meloidogyne. Pasteuria penetrans is established as an effective biological control agent for control and management o...

Effect of nematodes on rhizosphere colonization by seed-applied bacteria.

Science.gov (United States)

Knox, Oliver G G; Killham, Ken; Artz, Rebekka R E; Mullins, Chris; Wilson, Michael

2004-08-01

There is much interest in the use of seed-applied bacteria for biocontrol and biofertilization, and several commercial products are available. However, many attempts to use this strategy fail because the seed-applied bacteria do not colonize the rhizosphere. Mechanisms of rhizosphere colonization may involve active bacterial movement or passive transport by percolating water or plant roots. Transport by other soil biota is likely to occur, but this area has not been well studied. We hypothesized that interactions with soil nematodes may enhance colonization. To test this hypothesis, a series of microcosm experiments was carried out using two contrasting soils maintained under well-defined physical conditions where transport by mass water flow could not occur. Seed-applied Pseudomonas fluorescens SBW25 was capable of rhizosphere colonization at matric potentials of -10 and -40 kPa in soil without nematodes, but colonization levels were substantially increased by the presence of nematodes. Our results suggest that nematodes can have an important role in rhizosphere colonization by bacteria in soil.

Reciprocal Interactions between Nematodes and Their Microbial Environments.

Science.gov (United States)

Midha, Ankur; Schlosser, Josephine; Hartmann, Susanne

2017-01-01

Parasitic nematode infections are widespread in nature, affecting humans as well as wild, companion, and livestock animals. Most parasitic nematodes inhabit the intestines of their hosts living in close contact with the intestinal microbiota. Many species also have tissue migratory life stages in the absence of severe systemic inflammation of the host. Despite the close coexistence of helminths with numerous microbes, little is known concerning these interactions. While the environmental niche is considerably different, the free-living nematode Caenorhabditis elegans ( C. elegans ) is also found amongst a diverse microbiota, albeit on decaying organic matter. As a very well characterized model organism that has been intensively studied for several decades, C. elegans interactions with bacteria are much more deeply understood than those of their parasitic counterparts. The enormous breadth of understanding achieved by the C. elegans research community continues to inform many aspects of nematode parasitology. Here, we summarize what is known regarding parasitic nematode-bacterial interactions while comparing and contrasting this with information from work in C. elegans . This review highlights findings concerning responses to bacterial stimuli, antimicrobial peptides, and the reciprocal influences between nematodes and their environmental bacteria. Furthermore, the microbiota of nematodes as well as alterations in the intestinal microbiota of mammalian hosts by helminth infections are discussed.

Transgenic Strategies for Enhancement of Nematode Resistance in Plants

Directory of Open Access Journals (Sweden)

Muhammad A. Ali

2017-05-01

Full Text Available Plant parasitic nematodes (PPNs are obligate biotrophic parasites causing serious damage and reduction in crop yields. Several economically important genera parasitize various crop plants. The root-knot, root lesion, and cyst nematodes are the three most economically damaging genera of PPNs on crops within the family Heteroderidae. It is very important to devise various management strategies against PPNs in economically important crop plants. Genetic engineering has proven a promising tool for the development of biotic and abiotic stress tolerance in crop plants. Additionally, the genetic engineering leading to transgenic plants harboring nematode resistance genes has demonstrated its significance in the field of plant nematology. Here, we have discussed the use of genetic engineering for the development of nematode resistance in plants. This review article also provides a detailed account of transgenic strategies for the resistance against PPNs. The strategies include natural resistance genes, cloning of proteinase inhibitor coding genes, anti-nematodal proteins and use of RNA interference to suppress nematode effectors. Furthermore, the manipulation of expression levels of genes induced and suppressed by nematodes has also been suggested as an innovative approach for inducing nematode resistance in plants. The information in this article will provide an array of possibilities to engineer resistance against PPNs in different crop plants.

Regulation of naturally occurring radioactive materials in non-nuclear industries

International Nuclear Information System (INIS)

Scott, L.M.

1997-01-01

The volume and concentrations of naturally occurring radioactive material is large across a variety of industries commonly thought not to involve radioactive material. The regulation of naturally occurring radioactive material in the United States is in a state of flux. Inventory of naturally occurring radioactive materials is given, along with a range of concentrations. Current and proposed regulatory limits are presented. (author)

Formal synthesis of naturally occurring norephedrine

Indian Academy of Sciences (India)

A concise and simple synthesis of 1-hydroxy-phenethylamine derivatives has been achieved following classical organic transformations using commercially available chiral pools. The said derivatives were explored for the synthesis of naturally occurring bio-active small molecules. Formal synthesis of norephedrine, virolin ...

Nematode-Trapping Fungi.

Science.gov (United States)

Jiang, Xiangzhi; Xiang, Meichun; Liu, Xingzhong

2017-01-01

Nematode-trapping fungi are a unique and intriguing group of carnivorous microorganisms that can trap and digest nematodes by means of specialized trapping structures. They can develop diverse trapping devices, such as adhesive hyphae, adhesive knobs, adhesive networks, constricting rings, and nonconstricting rings. Nematode-trapping fungi have been found in all regions of the world, from the tropics to Antarctica, from terrestrial to aquatic ecosystems. They play an important ecological role in regulating nematode dynamics in soil. Molecular phylogenetic studies have shown that the majority of nematode-trapping fungi belong to a monophyletic group in the order Orbiliales (Ascomycota). Nematode-trapping fungi serve as an excellent model system for understanding fungal evolution and interaction between fungi and nematodes. With the development of molecular techniques and genome sequencing, their evolutionary origins and divergence, and the mechanisms underlying fungus-nematode interactions have been well studied. In recent decades, an increasing concern about the environmental hazards of using chemical nematicides has led to the application of these biological control agents as a rapidly developing component of crop protection.

Leachability of naturally occurring radioactive materials

International Nuclear Information System (INIS)

Desideri, D.; Feduzi, L.; Meli, M.A.; Roselli, C.

2006-01-01

Naturally occurring radioactive materials (NORM) are present in the environment and can be concentrated by technical activities, particularly those involving natural resources. These NORM deposits are highly stable and very insoluble under environmental conditions at the earth's surface. However, reducing or oxidant conditions or pH changes may enable a fraction of naturally occurring radionuclides to eventually be released to the environment. Leachability of 210 Pb and 210 Po was determined in three samples coming from a refractories production plant (dust, sludge, finished product), in one dust sample from a steelwork and in one ash sample coming from an electric power station. A sequential extraction method consisting of five operationally-defined fractions was used. The average leaching potential observed in the samples from the refractory industry is very low (mean values: 5.8% for 210 Pb and 1.7% for 210 Po). The 210 Pb and 210 Po leachability increases for the ash sample coming from an electric power plant using carbon (17.8% for 210 Pb and 10.0% for 210 Po); for the dust sample coming from a steelwork, the percent soluble fraction is 41.1% for 210 Pb and 8.5% for 210 Po. For all samples the results obtained show that 210 Pb is slightly more soluble than 210 Po. (author)

Endosymbiont-based immunity in Drosophila melanogaster against parasitic nematode infection.

Science.gov (United States)

Yadav, Shruti; Frazer, Joanna; Banga, Ashima; Pruitt, Katherine; Harsh, Sneh; Jaenike, John; Eleftherianos, Ioannis

2018-01-01

Associations between endosymbiotic bacteria and their hosts represent a complex ecosystem within organisms ranging from humans to protozoa. Drosophila species are known to naturally harbor Wolbachia and Spiroplasma endosymbionts, which play a protective role against certain microbial infections. Here, we investigated whether the presence or absence of endosymbionts affects the immune response of Drosophila melanogaster larvae to infection by Steinernema carpocapsae nematodes carrying or lacking their mutualistic Gram-negative bacteria Xenorhabdus nematophila (symbiotic or axenic nematodes, respectively). We find that the presence of Wolbachia alone or together with Spiroplasma promotes the survival of larvae in response to infection with S. carpocapsae symbiotic nematodes, but not against axenic nematodes. We also find that Wolbachia numbers are reduced in Spiroplasma-free larvae infected with axenic compared to symbiotic nematodes, and they are also reduced in Spiroplasma-containing compared to Spiroplasma-free larvae infected with axenic nematodes. We further show that S. carpocapsae axenic nematode infection induces the Toll pathway in the absence of Wolbachia, and that symbiotic nematode infection leads to increased phenoloxidase activity in D. melanogaster larvae devoid of endosymbionts. Finally, infection with either type of nematode alters the metabolic status and the fat body lipid droplet size in D. melanogaster larvae containing only Wolbachia or both endosymbionts. Our results suggest an interaction between Wolbachia endosymbionts with the immune response of D. melanogaster against infection with the entomopathogenic nematodes S. carpocapsae. Results from this study indicate a complex interplay between insect hosts, endosymbiotic microbes and pathogenic organisms.

Outcrossing and crossbreeding recovers deteriorated traits in laboratory cultured Steinernema carpocapsae nematodes.

Science.gov (United States)

Chaston, John M; Dillman, Adler R; Shapiro-Ilan, David I; Bilgrami, Anwar L; Gaugler, Randy; Hopper, Keith R; Adams, Byron J

2011-06-01

The nematode Steinernema carpocapsae infects and kills many pest insects in agro-ecosystems and is commonly used in biocontrol of these pests. Growth of the nematodes prior to distribution for biocontrol commonly results in deterioration of traits that are essential for nematode persistence in field applications. To better understand the mechanisms underlying trait deterioration of the efficacy of natural parasitism in entomopathogenic nematodes, we explored the maintenance of fitness related traits including reproductive capacity, heat tolerance, virulence to insects and 'tail standing' (formerly called nictation) among laboratory-cultured lines derived from natural, randomly mating populations of S. carpocapsae. Laboratory cultured nematode lines with fitness-related trait values below wild-type levels regained wild-type levels of reproductive and heat tolerance traits when outcrossed with a non-deteriorated line, while virulence and 'tail standing' did not deteriorate in our experiments. Crossbreeding two trait-deteriorated lines with each other also resulted in restoration of trait means to wild-type levels in most crossbred lines. Our results implicate inbreeding depression as the primary cause of trait deterioration in the laboratory cultured S. carpocapsae. We further suggest the possibility of creating inbred lines purged of deleterious alleles as founders in commercial nematode growth. Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.

Distribution and Population Dynamics of Nematodes in a Rice Field and Pasture in India

Science.gov (United States)

Mishra, C. C.; Dash, M. C.

1981-01-01

Ecological studies on soil nematodes were made in a tropical rice field and pasture. Parasitic species were more diversified in the pasture than in the rice field. Eighty-six and sixty percent of total nematodes occurred in the top 10 cm in rice field and pasture, respectively. Nematodes were not randomly or uniformly dispersed but aggregated. Parasitic forms were most abundant and correlated with root biomass in the 0-15-cm soil layer, the greatest number usually occurring at the 10-15-cm depth at both sites. In summer, however, they were densest at the 15-30-cm depth. Microbivores were most frequent in the top 5 cm of both sites. Micellaneous feeders (food sources uncertain) usually occurred in highest densities at the 15-30-cm depth. Predators showed no distinct depth preference. Temperature and moisture of the soil apparently played an important role in regulating nematode population. Peak densities of 31.3 × 10⁴/m² and 21.6 × 10⁴/m² at a 30-cm depth occurred in January, while minimum densities of 5.0-5.3 × 10⁴/m² and 4.1 × 10⁴/m² occurred in July-October and April in rice field and pasture, respectively. Monthly mean biomass of nematodes was 23.8 ± 4.5 mg/m² in rice field and 11.5 ± 1.5 mg/m² in pasture. PMID:19300801

Association of nematodes and dogwood cankers.

Science.gov (United States)

Self, L H; Bernard, E C

1994-03-01

Dogwood canker is a serious production problem of unknown etiology. From May 1985 through April 1989, cankers from 290 flowering dogwood trees in 15 separate nurseries were sampled for nematodes. Seventy-three percent (213) of the cankers contained nematodes. Panagrolaimus rigidus (Schneider) Thorne (115/290) and Aphelenchoides spp. (91/290) were the most frequently collected taxa. Panagrolaimus rigidus was reared on 2% water agar with unidentified bacteria as the food source. Aphelenchoides spp. were reared in antibiotic-amended agar culture with the fungus Glomerella cingulata (Stoneman) Spauld. &Schrenk as a food source. Repeated attempts to culture Aphelenchoides spp. on dogwood callus tissue were unsuccessful. Artificially created stem wounds inoculated with combinations of Aphelenchoides spp. and P. rigidus callused completely in 60 days with no indication of canker development. Very low numbers of nematodes were recovered from inoculated trees, but P. rigidus and one Aphelenchoides sp. were efficient dispersers and occurred in treatments other than those in which they were inoculated.

A naturally occurring trap for antiprotons

International Nuclear Information System (INIS)

Eades, J.; Morita, N.; Ito, T.M.

1993-05-01

The phenomenon of delayed annihilation of antiprotons in helium is the first instance of a naturally occurring trap for antimatter in ordinary matter. Recent studies of this effect at CERN are summarized, and plans are described for laser excitation experiments to test its interpretation in terms of metastable exotic helium atom formation. (author)

Immunoregulation by naturally occurring and disease-associated autoantibodies

DEFF Research Database (Denmark)

Nielsen, Claus H; Bendtzen, Klaus

2012-01-01

The role of naturally occurring autoantibodies (NAbs) in homeostasis and in disease manifestations is poorly understood. In the present chapter, we review how NAbs may interfere with the cytokine network and how NAbs, through formation of complement-activating immune complexes with soluble self......-antigens, may promote the uptake and presentation of self-molecules by antigen-presenting cells. Both naturally occurring and disease-associated autoantibodies against a variety of cytokines have been reported, including NAbs against interleukin (IL)-1α, IL-6, IL-8, IL-10, granulocyte-macrophage colony...

Natural variation in dauer pheromone production and sensing supports intraspecific competition in nematodes.

Science.gov (United States)

Bose, Neelanjan; Meyer, Jan M; Yim, Joshua J; Mayer, Melanie G; Markov, Gabriel V; Ogawa, Akira; Schroeder, Frank C; Sommer, Ralf J

2014-07-07

Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype [12]. To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Naturally Induced Secretions of the Potato Cyst Nematode Co-stimulate the Proliferation of Both Tobacco Leaf Protoplasts and Human Peripheral Blood Mononuclear Cells

NARCIS (Netherlands)

Goverse, A.; Rouppe van der Voort, J.N.A.M.; Rouppe van der voort, C.; Kavelaars, A.; Smant, G.; Schots, A.; Bakker, J.; Helder, J.

1999-01-01

Naturally induced secretions from infective juveniles of the potato cyst nematode Globodera rostochiensis co-stimulate the proliferation of tobacco leaf protoplasts in the presence of the synthetic phytohormones α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). With the use of a

Naturally occurring methyl salicylate glycosides.

Science.gov (United States)

Mao, Ping; Liu, Zizhen; Xie, Meng; Jiang, Rui; Liu, Weirui; Wang, Xiaohong; Meng, Shen; She, Gaimei

2014-01-01

As an important part of non steroids anti-inflammation drug (NSAIDs), salicylate has developed from natural substance salicylic acid to natrium salicylicum, to aspirin. Now, methyl salicylate glycoside, a new derivative of salicylic acid, is modified with a -COOH group integrated one methyl radical into formic ether, and a -OH linked with a monosaccharide, a disaccharide or a trisaccharide unit by glycosidic linkage. It has the similar pharmacological activities, anti-inflammatory, analgesic, antipyretic and antithrombotic as the previous salicylates' without resulting in serious side effects, particularly the gastrointestinal toxicity. Owing to the superiority of those significant bioactivities, methyl salicylate glycosides have became a hot research area in NSAIDs for several years. This paper compiles all 9 naturally occurring methyl salicylate glycosides, their distribution of the resource and pharmacological mechanism, which could contribute to the new drug discovery.

'David and Goliath' of the soil food web - Flagellates that kill nematodes

DEFF Research Database (Denmark)

Strandmark, Lisa Bjørnlund; Rønn, Regin

2008-01-01

Nematodes and flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food...... and showed for the first time that a small and common soil flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the flagellate cells and the nematode surface...... and occurs rapidly (within a few hours) at high flagellate density. At lower flagellate density, adult nematodes sometimes avoid attachment of flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one...

Predator-prey interactions of nematode-trapping fungi and nematodes: both sides of the coin.

Science.gov (United States)

Vidal-Diez de Ulzurrun, Guillermo; Hsueh, Yen-Ping

2018-05-01

Nematode-trapping fungi develop complex trapping devices to capture and consume nematodes. The dynamics of these organisms is especially important given the pathogenicity of nematodes and, consequently, the potential application of nematode-trapping fungi as biocontrol agents. Furthermore, both the nematodes and nematode-trapping fungi can be easily grown in laboratories, making them a unique manipulatable predator-prey system to study their coevolution. Several different aspects of these fungi have been studied, such as their genetics and the different factors triggering trap formation. In this review, we use the nematode-trapping fungus Arthrobotrys oligospora (which forms adhesive nets) as a model to describe the trapping process. We divide this process into several stages; namely attraction, recognition, trap formation, adhesion, penetration, and digestion. We summarize the latest findings in the field and current knowledge on the interactions between nematodes and nematode-trapping fungi, representing both sides of the predator-prey interaction.

Conserving and enhancing biological control of nematodes.

Science.gov (United States)

Timper, Patricia

2014-06-01

Conservation biological control is the modification of the environment or existing practices to protect and enhance antagonistic organisms to reduce damage from pests. This approach to biological control has received insufficient attention compared with inundative applications of microbial antagonists to control nematodes. This review provides examples of how production practices can enhance or diminish biological control of plant-parasitic nematodes and other soilborne pests. Antagonists of nematodes can be enhanced by providing supplementary food sources such as occurs when organic amendments are applied to soil. However, some organic amendments (e.g., manures and plants containing allelopathic compounds) can also be detrimental to nematode antagonists. Plant species and genotype can strongly influence the outcome of biological control. For instance, the susceptibility of the plant to the nematode can determine the effectiveness of control; good hosts will require greater levels of suppression than poor hosts. Plant genotype can also influence the degree of rhizosphere colonization and antibiotic production by antagonists, as well the expression of induced resistance by plants. Production practices such as crop rotation, fallow periods, tillage, and pesticide applications can directly disrupt populations of antagonistic organisms. These practices can also indirectly affect antagonists by reducing their primary nematode host. One of the challenges of conservation biological control is that practices intended to protect or enhance suppression of nematodes may not be effective in all field sites because they are dependent on indigenous antagonists. Ultimately, indicators will need to be identified, such as the presence of particular antagonists, which can guide decisions on where it is practical to use conservation biological control. Antagonists can also be applied to field sites in conjunction with conservation practices to improve the consistency, efficacy, and

Recent Duplication and Functional Divergence in Parasitic Nematode Levamisole-Sensitive Acetylcholine Receptors.

Directory of Open Access Journals (Sweden)

Thomas B Duguet

2016-07-01

Full Text Available Helminth parasites rely on fast-synaptic transmission in their neuromusculature to experience the outside world and respond to it. Acetylcholine plays a pivotal role in this and its receptors are targeted by a wide variety of both natural and synthetic compounds used in human health and for the control of parasitic disease. The model, Caenorhabditis elegans is characterized by a large number of acetylcholine receptor subunit genes, a feature shared across the nematodes. This dynamic family is characterized by both gene duplication and loss between species. The pentameric levamisole-sensitive acetylcholine receptor has been characterized from C. elegans, comprised of five different subunits. More recently, cognate receptors have been reconstituted from multiple parasitic nematodes that are found to vary in subunit composition. In order to understand the implications of receptor composition change and the origins of potentially novel drug targets, we investigated a specific example of subunit duplication based on analysis of genome data for 25 species from the 50 helminth genome initiative. We found multiple independent duplications of the unc-29, acetylcholine receptor subunit, where codon substitution rate analysis identified positive, directional selection acting on amino acid positions associated with subunit assembly. Characterization of four gene copies from a model parasitic nematode, Haemonchus contortus, demonstrated that each copy has acquired unique functional characteristics based on phenotype rescue of transgenic C. elegans and electrophysiology of receptors reconstituted in Xenopus oocytes. We found evidence that a specific incompatibility has evolved for two subunits co-expressed in muscle. We demonstrated that functional divergence of acetylcholine receptors, driven by directional selection, can occur more rapidly than previously thought and may be mediated by alteration of receptor assembly. This phenomenon is common among the

Drill machine guidance using natural occurring radiation

International Nuclear Information System (INIS)

Dahl, H.D.; Schroeder, R.L.; Williams, B.J.

1980-01-01

A drilling machine guidance system is described which uses only the naturally occuring radiation within the seam or stratum of interest. The apparatus can be used for guiding horizontal drilling machines through coal seams and the like. (U.K.)

Percieved functions of naturally occurring autobiographical memories

DEFF Research Database (Denmark)

Treebak, L. S.; Henriksen, J. R.; Lundhus, S.

2005-01-01

The main empirical reference on functions of autobiographical memories is still Hyman & Faries (1992) who used the cue-word-method and retrospective judgements. We used diaries to sample naturally occurring autobiographical memories and participants? perceived use of these. Results partly replicate...

Does scavenging extend the host range of entomopathogenic nematodes (Nematoda: Steinernematidae)?

Science.gov (United States)

Půza, Vladimír; Mrácek, Zdenĕk

2010-05-01

Living and freeze-killed natural and laboratory hosts, with different susceptibility to entomopathogenic nematodes, were exposed to the larvae of Steinernema affine and Steinernema kraussei in two different experimental arenas (Eppendorf tubes, Petri dishes), and the success of the colonisation and eventual progeny production were observed. Both nematodes were able to colonise both living and dead larvae of Galleria mellonella (Lepidoptera) and adult Blatella germanica (Blattodea) even though the progeny production in dead hosts was lower on average. Living carabid beetles, Poecilus cupreus, and elaterid larvae (Coleoptera) were resistant to the infection, however, both nematodes were able to colonise and multiply in several dead P. cupreus and in a majority of dead elaterid larvae. By scavenging, EPNs can utilise cadavers of insects that are naturally resistant to EPN infection, and so broaden their host range. (c) 2010 Elsevier Inc. All rights reserved.

Heterozygote deficits in cyst plant-parasitic nematodes: possible causes and consequences.

Science.gov (United States)

Montarry, Josselin; Jan, Pierre-Loup; Gracianne, Cecile; Overall, Andrew D J; Bardou-Valette, Sylvie; Olivier, Eric; Fournet, Sylvain; Grenier, Eric; Petit, Eric J

2015-04-01

Deviations of genotypic frequencies from Hardy-Weinberg equilibrium (HWE) expectations could reveal important aspects of the biology of populations. Deviations from HWE due to heterozygote deficits have been recorded for three plant-parasitic nematode species. However, it has never been determined whether the observed deficits were due (i) to the presence of null alleles, (ii) to a high level of consanguinity and/or (iii) to a Wahlund effect. The aim of the present work was, while taking into the possible confounding effect of null alleles, to disentangle consanguinity and Wahlund effect in natural populations of those three economically important cyst nematodes using microsatellite markers: Globodera pallida, G. tabacum and Heterodera schachtii, pests of potato, tobacco and sugar beet, respectively. The results show a consistent pattern of heterozygote deficiency in the three nematode species sampled at the spatial scale of the host plant. We demonstrate that the prevalence of null alleles is weak and that heterozygote deficits do not have a single origin. Our results suggested that it is restricted dispersal that leads to heterozygote deficits through both consanguinity and substructure, which effects can be linked to soil movement, cyst density, and the number of generations per year. We discuss potential implications for the durability of plant resistances that are used to protect crops against parasites in which mating between relatives occur. While consanguineous mating leads to homozygosity at all loci, including loci governing avirulence/virulence, which favours the expression of virulence when recessive, the Wahlund effect is expected to have no particular effect on the adaptation of nematodes to resistances. © 2015 John Wiley & Sons Ltd.

Connection between the decline of spruce and occurrence of animal pests, especially nematodes

Energy Technology Data Exchange (ETDEWEB)

Timans, U.

1986-12-01

In various regions of Bavaria, affected by the decline of spruce, attack by insects and especially nematodes was examined on diseased and healthy spruces. A connection between harmful forest insects and the decline of spruce did not become evident, neither over wide areas nor by examination of single trees. Attack by nematodes was examined in soil and wood samples and also in fine feeder roots of diseased and healthy trees. Plant-parasitic nematodes were not found in the wood and in feeder roots. Although root-parasitic nematodes were present in soil samples, their density was too little to account for a direct damage to spruce. They occurred likewise in samples from healthy and diseased trees. Plant-parasitic nematodes can thus be excluded as a possible causal agent for the decline of spruce.

Identification and functional analysis of secreted effectors from phytoparasitic nematodes.

Science.gov (United States)

Rehman, Sajid; Gupta, Vijai K; Goyal, Aakash K

2016-03-21

Plant parasitic nematodes develop an intimate and long-term feeding relationship with their host plants. They induce a multi-nucleate feeding site close to the vascular bundle in the roots of their host plant and remain sessile for the rest of their life. Nematode secretions, produced in the oesophageal glands and secreted through a hollow stylet into the host plant cytoplasm, are believed to play key role in pathogenesis. To combat these persistent pathogens, the identity and functional analysis of secreted effectors can serve as a key to devise durable control measures. In this review, we will recapitulate the knowledge over the identification and functional characterization of secreted nematode effector repertoire from phytoparasitic nematodes. Despite considerable efforts, the identity of genes encoding nematode secreted proteins has long been severely hampered because of their microscopic size, long generation time and obligate biotrophic nature. The methodologies such as bioinformatics, protein structure modeling, in situ hybridization microscopy, and protein-protein interaction have been used to identify and to attribute functions to the effectors. In addition, RNA interference (RNAi) has been instrumental to decipher the role of the genes encoding secreted effectors necessary for parasitism and genes attributed to normal development. Recent comparative and functional genomic approaches have accelerated the identification of effectors from phytoparasitic nematodes and offers opportunities to control these pathogens. Plant parasitic nematodes pose a serious threat to global food security of various economically important crops. There is a wealth of genomic and transcriptomic information available on plant parasitic nematodes and comparative genomics has identified many effectors. Bioengineering crops with dsRNA of phytonematode genes can disrupt the life cycle of parasitic nematodes and therefore holds great promise to develop resistant crops against plant

Phylogency and Evolution of Nematodes

NARCIS (Netherlands)

Bert, W.; Karssen, G.; Helder, J.

2011-01-01

Many plant-parasitic nematodes including members of the genera Meloidogyne (root-knot nematodes), Heterodera and Globodera (cyst nematodes) and Pratylenchus (lesion nematodes) are studied as they cause major damage to crops such as potato, tomato, soybean and sugar beet. Both for fundamental reasons

Unifying the functional diversity in natural and cultivated soils using the overall body-mass distribution of nematodes.

Science.gov (United States)

Mulder, Christian; Maas, Rob

2017-11-28

Sustainable use of our soils is a key goal for environmental protection. As many ecosystem services are supported belowground at different trophic levels by nematodes, soil nematodes are expected to provide objective metrics for biological quality to integrate physical and chemical soil variables. Trait measurements of body mass carried out at the individual level can in this way be correlated with environmental properties that influence the performance of soil biota. Soil samples were collected across 200 sites (4 soil types and 5 land-use types resulting in 9 combinations) during a long-term monitoring programme in the Netherlands and the functional diversity of nematode communities was investigated. Using three commonly used functional diversity indices applicable to single traits (Divergence, Evenness and Richness), a unified index of overall body-mass distribution is proposed to better illustrate the application of functional metrics as a descriptor of land use. Effects of land use and soil chemistry on the functional diversity of nematodes were demonstrated and a combination of environmental factors accounts for the low functional value of Scots Pine forest soils in comparison to the high functional value of heathland soils, whereas human factors account for the low functional and chemical values of arable fields. These findings show an unexpected high functional vulnerability of nematodes inhabiting clay-rich soils in comparison to sandy soils and support the notion that soil C:N ratio is a major driver of biodiversity. The higher the C:N ratio, the higher the overall diversity, as soil nematodes cope better with nutrient-poor agroecosystems under less intense fertilization. A trait-based way focusing on size distribution of nematodes is proposed to maintain environmental health by monitoring the overall diversity in soil biota, keeping agriculture and forestry sustainable.

A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans.

Science.gov (United States)

Choi, Jae Im; Yoon, Kyoung-Hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin

2016-03-01

Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator-prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds.

A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans

Science.gov (United States)

Choi, Jae Im; Yoon, Kyoung-hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin

2016-01-01

Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator–prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds. PMID:26241504

Arrested larval development in cattle nematodes.

Science.gov (United States)

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.

Caenorhabditis elegans Predation on Bacillus anthracis: Decontamination of Spore Contaminated Soil with Germinants and Nematodes.

Science.gov (United States)

Schelkle, Bettina; Choi, Young; Baillie, Leslie W; Richter, William; Buyuk, Fatih; Celik, Elif; Wendling, Morgan; Sahin, Mitat; Gallagher, Theresa

2017-01-01

Remediation of Bacillus anthracis -contaminated soil is challenging and approaches to reduce overall spore levels in environmentally contaminated soil or after intentional release of the infectious disease agent in a safe, low-cost manner are needed. B. anthracis spores are highly resistant to biocides, but once germinated they become susceptible to traditional biocides or potentially even natural predators such as nematodes in the soil environment. Here, we describe a two-step approach to reducing B. anthracis spore load in soil during laboratory trials, whereby germinants and Caenorhabditis elegans nematodes are applied concurrently. While the application of germinants reduced B. anthracis spore load by up to four logs depending on soil type, the addition of nematodes achieved a further log reduction in spore count. These laboratory based results suggest that the combined use of nematodes and germinants could represent a promising approach for the remediation of B. anthracis spore contaminated soil. Originality-Significance Statement: This study demonstrates for the first time the successful use of environmentally friendly decontamination methods to inactivate Bacillus anthracis spores in soil using natural predators of the bacterium, nematode worms.

Nematode assemblages in the deep-sea benthos of the Norwegian Sea

Science.gov (United States)

Jensen, Preben

1988-07-01

The deep-sea benthos of the Norwegian Sea contains 20-204 nematodes per 10 cm 2 down to 3 cm depth at seven stations sampled between 970 and 3294 m water depth. The majority of nematodes occur in the uppermost cm. Biomass varies from 3 to 73 μg C per 10 cm 2. Individual adult weight of the most dominant species differs by a factor of almost 1000, i.e. from 3-4 ng C to 3400 ng C; however, the majority of the nematodes is small-sized. Species diversity and evenness are high at all stations and each station harbours its specific fauna with little overlap between stations. Analysis of trophic group composition suggests that microbial feeding types (deposit and epistrate feeders) prevail in the deep-sea benthos; predators and scavengers are scarce. It is concluded that the nematode assemblage at each station consists of a mosaic of many microhabitats. The small nematode body weight probably results from limited food supply and/or poor food quality.

Generalists at the interface: Nematode transmission between wild and domestic ungulates.

Science.gov (United States)

Walker, Josephine G; Morgan, Eric R

2014-12-01

Many parasitic nematode species are generalists capable of infecting multiple host species. The complex life cycle of nematodes, involving partial development outside of the host, facilitates transmission of these parasites between host species even when there is no direct contact between hosts. Infective nematode larvae persist in the environment, and where grazing or water sources are shared ingestion of parasite larvae deposited by different host species is likely. In this paper we examine the extent to which nematode parasite species have been observed in sympatric wild and domestic ungulates. First, using existing host-parasite databases, we describe expected overlap of 412 nematode species between 76 wild and 8 domestic ungulate host species. Our results indicate that host-specific parasites make up less than half of the nematode parasites infecting any particular ungulate host species. For wild host species, between 14% (for common warthog) and 76% (for mouflon) of parasitic nematode species are shared with domestic species. For domestic host species, between 42% (for horse) and 77% (for llamas/alpacas) of parasitic nematode species are shared with wild species. We also present an index of liability to describe the risk of cross-boundary parasites to each host species. We then examine specific examples from the literature in which transmission of nematode parasites between domestic and wild ungulates is described. However, there are many limitations in the existing data due to geographical bias and certain host species being studied more frequently than others. Although we demonstrate that many species of parasitic nematode are found in both wild and domestic hosts, little work has been done to demonstrate whether transmission is occurring between species or whether similar strains circulate separately. Additional research on cross-species transmission, including the use of models and of genetic methods to define strains, will provide evidence to answer this

Generalists at the interface: Nematode transmission between wild and domestic ungulates

Directory of Open Access Journals (Sweden)

Josephine G. Walker

2014-12-01

Full Text Available Many parasitic nematode species are generalists capable of infecting multiple host species. The complex life cycle of nematodes, involving partial development outside of the host, facilitates transmission of these parasites between host species even when there is no direct contact between hosts. Infective nematode larvae persist in the environment, and where grazing or water sources are shared ingestion of parasite larvae deposited by different host species is likely. In this paper we examine the extent to which nematode parasite species have been observed in sympatric wild and domestic ungulates. First, using existing host–parasite databases, we describe expected overlap of 412 nematode species between 76 wild and 8 domestic ungulate host species. Our results indicate that host-specific parasites make up less than half of the nematode parasites infecting any particular ungulate host species. For wild host species, between 14% (for common warthog and 76% (for mouflon of parasitic nematode species are shared with domestic species. For domestic host species, between 42% (for horse and 77% (for llamas/alpacas of parasitic nematode species are shared with wild species. We also present an index of liability to describe the risk of cross-boundary parasites to each host species. We then examine specific examples from the literature in which transmission of nematode parasites between domestic and wild ungulates is described. However, there are many limitations in the existing data due to geographical bias and certain host species being studied more frequently than others. Although we demonstrate that many species of parasitic nematode are found in both wild and domestic hosts, little work has been done to demonstrate whether transmission is occurring between species or whether similar strains circulate separately. Additional research on cross-species transmission, including the use of models and of genetic methods to define strains, will provide

Findings of entomopathogenic nematodes (Rhabditida, Steinernematidae) in nature reserves in Ukraine

Czech Academy of Sciences Publication Activity Database

Yakovlev, Ye. B.; Kharchenko, V. A.; Mráček, Zdeněk

2014-01-01

Roč. 48, č. 3 (2014), s. 203-210 ISSN 0084-5604 R&D Projects: GA MŠk LH12105 Institutional support: RVO:60077344 Keywords : entomopathogenic nematode Subject RIV: EH - Ecology, Behaviour http://www.degruyter.com/view/j/vzoo.2014.48.issue-3/vzoo-2014-0023/vzoo-2014-0023.xml

First use of soil nematode communities as bioindicator of radiation impact in the Chernobyl exclusion zone

Energy Technology Data Exchange (ETDEWEB)

Lecomte, C.; Bonzom, J.M.; Adam-Guillermin, C. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, LECO (France); Della-Vedova, C. [Magelis, Cadenet (France); Beaugelin-Seiller, K. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, LM2E (France); Gaschak, S. [Chernobyl Center for Nuclear safety, Radioactive waste and Radioecology, International Radioecology Laboratory (Ukraine); Coppin, F. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, L2BT (France); Garnier-Laplace, J. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS (France)

2014-07-01

The aim of the study was to assess the effects of former radioactive contamination on the structure of the nematode community in sites affected by the fallout from the Chernobyl accident that occurred on 26, April 1986. Nematodes were collected in spring 2011 from 18 forest sites of the Chernobyl Exclusion Zone (CEZ). The external gamma dose rates, measured from radiophotoluminescent dosimeters (RPL) varied from 0.2 to 22 μGy h{sup -1} between sites. In parallel, the Total dose rates (TDR) absorbed by nematodes were predicted from measured soil activity concentrations, Dose Conversion Coefficients (DCC, calculated by the EDEN software) and Soil-to-biota concentration ratios (from the ERICA tool database). Results showed that TDR were one order of magnitude above the external gamma dose rate measured from RPL. This is mainly due to the contribution of alpha ({sup 241}Am,{sup 238,239,240}Pu) and beta ({sup 90}Sr, and {sup 137}Cs) emitters in the external dose rate. The small size (in the order of mm) of nematodes promoted a high energy deposition throughout the organisms without fading, giving more weight to external dose rate induced by alpha-and beta-emitters, relatively to gamma-emitters. Analysis of the nematode community showed a majority of bacterial-, plant-, and fungal- feeder nematodes and almost none of the disturbance sensitive families whatever the level of radioactive contamination. Multiple regression analysis was used to establish relationships between ecological features (nematodes abundance and family diversity, indices of ecosystem structure and function) to the environmental characteristics (TDR and soil physico-chemical properties). No evidence was found that nematode total abundance and family diversity were impaired by the radiological contamination. However, the Nematode Channel Ratio (defining the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR suggesting that the radioactive

An electron-microscopical analysis of capture and initial stages of penetration of nematodes by Arthrobotrys oligospora

NARCIS (Netherlands)

Veenhuis, Marten; Nordbring-Hertz, Birgit; Harder, Wim

1985-01-01

A detailed analysis was made of the capture and subsequent penetration of nematodes by the nematophagous fungus Arthrobotrys oligospora using different electron-microscopical techniques. Capture of nematodes by this fungus occurred on complex hyphal structures (traps) and was effectuated by an

Introduction to naturally occurring radioactive material

Energy Technology Data Exchange (ETDEWEB)

Egidi, P.

1997-08-01

Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. We are also bathed in a sea of natural radiation coming from the sun and deep space. Living systems have adapted to these levels of radiation and radioactivity. But some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. Other activities, such as flying at high altitudes, expose us to elevated levels of NORM. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose

Legionella-protozoa-nematode interactions in aquatic biofilms and influence of Mip on Caenorhabditis elegans colonization.

Science.gov (United States)

Rasch, Janine; Krüger, Stefanie; Fontvieille, Dominique; Ünal, Can M; Michel, Rolf; Labrosse, Aurélie; Steinert, Michael

2016-09-01

Legionella pneumophila, the causative agent of Legionnaireś disease, is naturally found in aquatic habitats. The intracellular life cycle within protozoa pre-adapted the "accidental" human pathogen to also infect human professional phagocytes like alveolar macrophages. Previous studies employing the model organism Caenorhabditis elegans suggest that also nematodes might serve as a natural host for L. pneumophila. Here, we report for the first time from a natural co-habitation of L. pneumophila and environmental nematode species within biofilms of a warm water spring. In addition, we identified the protozoan species Oxytricha bifaria, Stylonychia mytilus, Ciliophrya sp. which have never been described as potential interaction partners of L. pneumophila before. Modeling and dissection of the Legionella-protozoa-nematode interaction revealed that C. elegans ruptures Legionella-infected amoebal cells and by this means incorporate the pathogen. Further infection studies revealed that the macrophage infectivity potentiator (Mip) protein of L. pneumophila, which is known to bind collagen IV during human lung infection, promotes the colonization of the intestinal tract of L4 larvae of C. elegans and negatively influences the life span of the worms. The Mip-negative L. pneumophila mutant exhibited a 32-fold reduced colonization rate of the nematodes after 48h when compared to the wild-type strain. Taken together, these studies suggest that nematodes may serve as natural hosts for L. pneumophila, promote their persistence and dissemination in the environment, and co-evolutionarily pre-adapt the pathogen for interactions with extracellular constituents of human lung tissue. Copyright © 2016 Elsevier GmbH. All rights reserved.

Influence of the Sting Nematode, Belonolaimus longicaudalus, on Young Citrus Trees.

Science.gov (United States)

Kaplan, D T

1985-10-01

The sting nematode, Belonolaimus longicaudatus, was associated with poor growth of citrus in a central Florida nursery. Foliage of trees was sparse and chlorotic. Affected rootstocks included Changsha and Cleopatra mandarin orange; Flying Dragon, Rubidoux, and Jacobsen trifoliate orange; Macrophylla and Milam lemon; Palestine sweet lime; sour orange; and the hybrids - Carrizo, Morton, and Rusk citrange and Swingle citrumelo. Root symptoms included apical swelling, development of swollen terminals containing 3-5 apical meristems and hyperplastic tissue, coarse roots, and a reduction in the number of fibrous roots. Population densities as high as 392 sting nematodes per liter soil were detected, with 80% of the population occurring in the top 30 cm of soil; however, nematodes were detected to 107 cm deep. Although an ectoparasite, the nematode was closely associated with citrus root systems and was transported with bare root nursery stock. Disinfestation was accomplished by hot water treatment (49 C for 5 minutes).

Olfactory circuits and behaviors of nematodes.

Science.gov (United States)

Rengarajan, Sophie; Hallem, Elissa A

2016-12-01

Over one billion people worldwide are infected with parasitic nematodes. Many parasitic nematodes actively search for hosts to infect using volatile chemical cues, so understanding the olfactory signals that drive host seeking may elucidate new pathways for preventing infections. The free-living nematode Caenorhabditis elegans is a powerful model for parasitic nematodes: because sensory neuroanatomy is conserved across nematode species, an understanding of the microcircuits that mediate olfaction in C. elegans may inform studies of olfaction in parasitic nematodes. Here we review circuit mechanisms that allow C. elegans to respond to odorants, gases, and pheromones. We also highlight work on the olfactory behaviors of parasitic nematodes that lays the groundwork for future studies of their olfactory microcircuits. Copyright © 2016 Elsevier Ltd. All rights reserved.

Deposition of naturally occurring radioactivity in oil and gas production

International Nuclear Information System (INIS)

Lysebo, I.; Strand, T.

1997-01-01

This booklet contains general information about naturally occurring radioactive materials, NORM, in production of oil and natural gas, occupational doses, radiation protection procedures and measures, and classification methods of contaminated equipment. 6 refs., 1 fig., 1 tab

The significance of ecology in the development of Verticillium chlamydosporium as a biological control agent against root-knot nematodes (Meloidogyne spp.)

NARCIS (Netherlands)

Leij, de F.A.A.M.

1992-01-01

A thorough understanding of the interactions which occur between nematode parasites and nematode pests and the influence of biotic and abiotic factors on these interactions, is essential in the development of biological control agents for nematodes. The aim of this study was to develop a

Efficacy of the amino-acetonitrile derivative, monepantel, against experimental and natural adult stage gastro-intestinal nematode infections in sheep.

Science.gov (United States)

Sager, Heinz; Hosking, Barry; Bapst, Béatrice; Stein, Philip; Vanhoff, Kathleen; Kaminsky, Ronald

2009-01-22

Multiple drug resistance by nematodes, against anthelmintics has become an important economic problem in sheep farming worldwide. Here we describe the efficacy of monepantel, a developmental molecule from the recently discovered anthelmintic class, the amino-acetonitrile derivatives (AADs). Efficacy was tested against adult stage gastro-intestinal nematodes (GINs) in experimentally and naturally infected sheep at a dose of 2.5mg/kg body weight when administered as an oral solution. Some of the isolates used in experimental infection studies were known to be resistant to the benzimidazoles or levamisole anthelmintics; strains resistant to the macrocyclic lactones were not available for these tests. Worm count-based efficacies of >98% were determined in these studies. As an exception, Oesophagostomum venulosum was only reduced by 88% in one study, albeit with a low worm burden in the untreated controls (geometric mean 15.4 worms). Similar efficacies for monepantel were also confirmed in naturally infected sheep. While the efficacy against most species was >99%, the least susceptible species was identified as Nematodirus spathiger, and although efficacy was 92.4% in one study it was generally >99%. Several animals were infected with Trichuris ovis, which was not eliminated after the treatment. Monepantel demonstrated high activity against a broad range of the important GINs of sheep, which makes this molecule an interesting candidate for use in this species, particularly in regions with problems of anthelmintic resistance. Monepantel was well tolerated by the treated sheep, with no treatment related adverse events documented.

Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

Science.gov (United States)

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

Discovery of genomic intervals that underlie nematode responses to benzimidazoles.

Science.gov (United States)

Zamanian, Mostafa; Cook, Daniel E; Zdraljevic, Stefan; Brady, Shannon C; Lee, Daehan; Lee, Junho; Andersen, Erik C

2018-03-01

Parasitic nematodes impose a debilitating health and economic burden across much of the world. Nematode resistance to anthelmintic drugs threatens parasite control efforts in both human and veterinary medicine. Despite this threat, the genetic landscape of potential resistance mechanisms to these critical drugs remains largely unexplored. Here, we exploit natural variation in the model nematodes Caenorhabditis elegans and Caenorhabditis briggsae to discover quantitative trait loci (QTL) that control sensitivity to benzimidazoles widely used in human and animal medicine. High-throughput phenotyping of albendazole, fenbendazole, mebendazole, and thiabendazole responses in panels of recombinant lines led to the discovery of over 15 QTL in C. elegans and four QTL in C. briggsae associated with divergent responses to these anthelmintics. Many of these QTL are conserved across benzimidazole derivatives, but others show drug and dose specificity. We used near-isogenic lines to recapitulate and narrow the C. elegans albendazole QTL of largest effect and identified candidate variants correlated with the resistance phenotype. These QTL do not overlap with known benzimidazole target resistance genes from parasitic nematodes and present specific new leads for the discovery of novel mechanisms of nematode benzimidazole resistance. Analyses of orthologous genes reveal conservation of candidate benzimidazole resistance genes in medically important parasitic nematodes. These data provide a basis for extending these approaches to other anthelmintic drug classes and a pathway towards validating new markers for anthelmintic resistance that can be deployed to improve parasite disease control.

Introduction to naturally occurring radioactive material

International Nuclear Information System (INIS)

Egidi, P.

1997-01-01

Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. Some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose-based standards. So when is TENORM a problem? Where is it a problem? That depends on when, where, and whom you talk to exclamation point We will start by reviewing background radioactivity, then we will proceed to the geology, mobility, and variability of these

Nematode parasites of animals are more prone to develop xenobiotic resistance than nematode parasites of plants

Directory of Open Access Journals (Sweden)

Silvestre A.

2004-06-01

Full Text Available In this paper, we concentrate on a comparison of plant and animal-parasitic nematodes, to gain insight into the factors that influence the acquisition of the drug resistance by nematodes. Comparing nematode parasite of domestic animals and cultivated plants, it appears that drug resistance threatens only domestic animal production. Does the paucity of report on nematicide field resistance reflect reality or, is nematicide resistance bypassed by other management practices, specific to cultivated plants (i.e. agricultural control ? First, it seems that selection pressure by treatments in plants is not as efficient as selection pressure in ruminants. Agronomic practices (i.e. sanitation, early planting, usage of nematodes resistant cultivar and crop rotation are frequently used to control parasitic-plant nematodes. Although the efficiency of such measures is generally moderate to high, integrated approaches are developing successfully in parasitic-plant nematode models. Secondly, the majority of anthelmintic resistance cases recorded in animal-parasitic nematodes concern drug families that are not used in plant-parasitic nematodes control (i.e. benzimidazoles, avermectines and levamisole. Thirdly, particular life traits of parasitic-plant nematodes (low to moderate fecundity and reproductive strategy are expected to reduce probability of appearance and transmission of drug resistance genes. It has been demonstrated that, for a large number of nematodes such as Meloidogyne spp., the mode of reproduction by mitotic parthenogenesis reduced genetic diversity of populations which may prevent a rapid drug resistance development. In conclusion, anthelmintic resistance develops in nematode parasite of animals as a consequence of an efficient selection pressure. Early detection of anthelmintic resistance is then crucial : it is not possible to avoid it, but only to delay its development in farm animal industry.

A survival-reproduction trade-off in entomopathogenic nematodes mediated by their bacterial symbionts.

Science.gov (United States)

Emelianoff, Vanya; Chapuis, Elodie; Le Brun, Nathalie; Chiral, Magali; Moulia, Catherine; Ferdy, Jean-Baptiste

2008-04-01

In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.

Differential Selection by Nematodes on an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

Science.gov (United States)

Kim, Tae Gwan; Knudsen, Guy R

2018-03-15

Trophic interactions of introduced biocontrol fungi with soil animals can bea key determinant in the fungal proliferation and activity.This study investigated trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes ( p nematodes did not increase in number and the added Aphelenchoides sp. nematodes almost disappeared by day 10. With ThzID1-M3, population growth of nematodes was rapid between 5 and 10 days after treatment. ThzID1-M3 biomass peaked on day 5, dropped at day 10, and then almost disappeared at day 20, which was not influenced by the addition of nematodes.In contrast, a large quantity of ThzID1-M3 hyphae were present in a heat-treated soil in which nematodes were eliminated.Total fungal biomass in all treatments peaked on day 5 and subsequently decreased.Addition of nematodes increased the total fungal biomass ( p nematode population growth; however, hyphae of the introduced fungus when densely localized did.The results suggest that soil fungivorous nematodes are an important constraint onhyphal proliferation of fungal agents introduced into natural soils.

Leaching Properties of Naturally Occurring Heavy Metals from Soils

Science.gov (United States)

Zhang, M.; Hoshino, M.; Yoshikawa, M.; Hara, J.; Sugita, H.

2014-12-01

The major threats to human health from heavy metals are associated with exposure to arsenic, lead, cadmium, chromium, mercury, as well as some other elements. The effects of such heavy metals on human health have been extensively studied and reviewed by international organizations such as WHO. Due to their toxicity, heavy metal contaminations have been regulated by national environmental standards in many countries, and/or laws such as the Soil Contamination Countermeasures Act in Japan. Leaching of naturally occurring heavy metals from the soils, especially those around abandoned metal mines into surrounding water systems, either groundwater or surface water systems, is one of the major pathways of exposure. Therefore, understanding the leaching properties of toxic heavy metals from naturally polluted soils is of fundamentally importance for effectively managing abandoned metal mines, excavated rocks discharged from infrastructure constructions such as tunneling, and/or selecting a pertinent countermeasure against pollution when it is necessary. In this study, soil samples taken from the surroundings of abandoned metal mines in different regions in Japan were collected and analyzed. The samples contained multiple heavy metals such as lead, arsenic and chromium. Standard leaching test and sequential leaching test considering different forms of contaminants, such as trivalent and pentavalent arsenics, and trivalent and hexavalent chromiums, together with standard test for evaluating total concentration, X-ray Fluorescence Analysis (XRF), X-ray diffraction analysis (XRD) and Cation Exchange Capacity (CEC) tests were performed. In addition, sequential leaching tests were performed to evaluate long-term leaching properties of lead from representative samples. This presentation introduces the details of the above experimental study, discusses the relationships among leaching properties and chemical and mineral compositions, indicates the difficulties associated with

The evolutionary position of nematodes

Directory of Open Access Journals (Sweden)

Gojobori Takashi

2002-04-01

Full Text Available Abstract Background The complete genomes of three animals have been sequenced by global research efforts: a nematode worm (Caenorhabditis elegans, an insect (Drosophila melanogaster, and a vertebrate (Homo sapiens. Remarkably, their relationships have yet to be clarified. The confusion concerns the enigmatic position of nematodes. Traditionally, nematodes have occupied a basal position, in part because they lack a true body cavity. However, the leading hypothesis now joins nematodes with arthropods in a molting clade, Ecdysozoa, based on data from several genes. Results We tested the Ecdysozoa hypothesis with analyses of more than 100 nuclear protein alignments, under conditions that would expose biases, and found that it was not supported. Instead, we found significant support for the traditional hypothesis, Coelomata. Our result is robust to different rates of sequence change among genes and lineages, different numbers of taxa, and different species of nematodes. Conclusion We conclude that insects (arthropods are genetically and evolutionarily closer to humans than to nematode worms.

Damage-associated responses of the host contribute to defence against cyst nematodes but not root-knot nematodes.

Science.gov (United States)

Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S; Lozano-Torres, Jose L; Grundler, Florian M W; Siddique, Shahid

2017-12-16

When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in plant-nematode interactions remain unexplored. Here, we characterized the role of a group of cell wall receptor proteins in Arabidopsis, designated as polygalacturonase-inhibiting proteins (PGIPs), during infection with the cyst nematode Heterodera schachtii and the root-knot nematode Meloidogyne incognita. PGIPs are encoded by a family of two genes in Arabidopsis, and are involved in the formation of active OG elicitors. Our results show that PGIP gene expression is strongly induced in response to cyst nematode invasion of roots. Analyses of loss-of-function mutants and overexpression lines revealed that PGIP1 expression attenuates infection of host roots by cyst nematodes, but not root-knot nematodes. The PGIP1-mediated attenuation of cyst nematode infection involves the activation of plant camalexin and indole-glucosinolate pathways. These combined results provide new insights into the molecular mechanisms underlying plant damage perception and response pathways during infection by cyst and root-knot nematodes, and establishes the function of PGIP in plant resistance to cyst nematodes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Epidemiological studies of nematodes in fishes

International Nuclear Information System (INIS)

Qamar, M.F.; Butt, K.; Qureshi, N.A.

2014-01-01

Three hundred fresh water fishes of six species were collected from six different fish farms of Lahore for the prevalence of nematodes. Out of 300 fishes examined, 12 were found to be infected with the helminthes, majority of them were isolated from the stomach and intestines. The following two species of nematodes were recorded; Capillaria spp. and Eustrongylides spp. The overall prevalence of intestinal nematodes was recorded as 4%(12/300). The prevalence of nematodes was recorded on monthly basis which ranged from 0-8%. The highest prevalence of nematodes was 8% (4/50) during March, while the lowest prevalence was noted in June 0%.Singharee (Sperata sawari) showed the maximum infestation of nematodes of 8% (4/50), whereas in Silver Carp (Hypopthaimichthys molitrix) minimum prevalence of nematode (0%) was noted. The prevalence of different nematode in a particular fish specie was also recorded, and it was stated that overall prevalence of capillaria spp. was 6% in Rahu (Labeo rohita) and Saul (Channa marullius). Similarly overall infestation of Eustrongylides sp. was recorded as 4% in Singharee (Sperata sawari) and Silver carp (Hypopthaimichthys molitrix). The nematode intensity might be linked with the genetic makeup, intestinal vigor, and other managemental and environmental factors. (author)

Naturally occurring radionuclides in agricultural products: An overview

International Nuclear Information System (INIS)

Hanlon, E.A.

1994-01-01

Low levels of naturally occurring radionuclides exist in phosphatic clays, a by-product of phosphatic mining and beneficiation processes. Concerns about these radionuclides entering the human food chain were an immediate research priority before the phosphate clays could be reclaimed for intensive agricultural purposes. Efforts included the assembly of a large body of data from both sons and plants, part of which were produced by the Polk County (Florida) Mined Lands Agricultural Research/Demonstration Project MLAR/DP. Additional detailed studies involving dairy and beef cattle (Bos taurus) were conducted by researchers working with the MLAR/DP. A national symposium was conducted in which data concerning the MLAR/DP work and other research projects also dealing with naturally occurring radionuclides in agriculture could be discussed. The symposium included invited review papers dealing with the identification of radionuclide geological origins, the geochemistry and movement of radionuclides within the environment, mechanisms of plant uptake, entry points into the food chain, and evaluation of dose and risk assessment to the consumer of low levels of radionuclides. The risk to human health of an individual obtaining 0.1 of his or her dietary intake from crops produced on phosphatic clays increased by 1 in 5 x 10 6 /yr above a control individual consuming no food grown on phosphatic clays. Leaf tissues were found to be generally higher than fruit, grain, or root tissues. The natural range in radionuclide content among various food types was greater than the difference in radionuclides content between the same food produced on phosphatic clays vs. natural soils. 19 refs

Nematode communities in contaminated river sediments

International Nuclear Information System (INIS)

Heininger, Peter; Hoess, Sebastian; Claus, Evelyn; Pelzer, Juergen; Traunspurger, Walter

2007-01-01

Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure. - Nematode community structure of river sediments is related to pollution and site structure

Nematode communities in contaminated river sediments

Energy Technology Data Exchange (ETDEWEB)

Heininger, Peter [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Hoess, Sebastian [Ecossa - Ecological Sediment and Soil Assessment, Thierschstr. 43, 80538 Munich (Germany); Claus, Evelyn [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Pelzer, Juergen [Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068 Koblenz (Germany); Traunspurger, Walter [University of Bielefeld, Department of Animal Ecology, Morgenbreede 45, 33615 Bielefeld (Germany)]. E-mail: traunspurger@uni-bielefeld.de

2007-03-15

Nematode communities of eight sites from three river catchments were investigated in terms of the genera composition, feeding types, and life-history strategists. The sampling sites showed a gradient of anthropogenic contamination with heavy metals and organic pollutants being important factors in differentiating the sites. Nematode community structure was related to sediment pollution and the hydro-morphological structure of the sampling sites. Heavily contaminated sites were characterized by communities with high relative abundances of omnivorous and predacious nematodes (Tobrilus, c-p 3; Mononchus, c-p 4), while sites with low to medium contamination were dominated by bacterivorous nematodes (Monhystera, Daptonema; c-p 2) or suction feeders (Dorylaimus, c-p 4). The relatively high Maturity Index values in the heavily polluted sites were surprising. Nematodes turned out to be a suitable organism group for monitoring sediment quality, with generic composition being the most accurate indicator for assessing differences in nematode community structure. - Nematode community structure of river sediments is related to pollution and site structure.

Radioactivity in papers: the concentration and source of naturally occurring radionuclides

International Nuclear Information System (INIS)

Kobashi, Asaya

2005-01-01

The radioactivities of naturally occurring radionuclides ( 226 Ra, 228 Ra, 228 Th and 40 K) in papers such as magazines, newspapers, and copying papers produced in Japan were determined by gamma-ray spectrometry to obtain information on radioactivity level of papers. The X-ray diffraction measurement of the samples was also carried out to elucidate the source of radionuclides contained in them. The average 226 Ra, 228 Ra, 228 Th, and 40 K contents of pocket-sized books were 6.4, 21.5, 23.7, and 18.8 Bq kg -1 , respectively, and those of other kinds of samples were near to or less than the values. The 228 Th content was generally somewhat higher than the 228 Ra content. Possibly 228 Ra was leached from the raw materials of the papers to water during their production in preference to 228 Th. The concentrations of the naturally occurring radionuclides were correlated to each other. The X-ray diffraction study showed that kaolinite, talc, and calcite were contained in the papers. The kaolinite content of the samples was correlated to the concentrations of the naturally occurring radionuclides, indicating that the naturally occurring radionuclides in the paper samples were mainly brought with kaolinite used as filler or coating pigment in the papers. The regression analysis of the data showed that the natural radioactivity content of filler kaolinite was higher than that of pigment kaolinite. (author)

RNAi effector diversity in nematodes.

Directory of Open Access Journals (Sweden)

Johnathan J Dalzell

2011-06-01

Full Text Available While RNA interference (RNAi has been deployed to facilitate gene function studies in diverse helminths, parasitic nematodes appear variably susceptible. To test if this is due to inter-species differences in RNAi effector complements, we performed a primary sequence similarity survey for orthologs of 77 Caenorhabditis elegans RNAi pathway proteins in 13 nematode species for which genomic or transcriptomic datasets were available, with all outputs subjected to domain-structure verification. Our dataset spanned transcriptomes of Ancylostoma caninum and Oesophagostomum dentatum, and genomes of Trichinella spiralis, Ascaris suum, Brugia malayi, Haemonchus contortus, Meloidogyne hapla, Meloidogyne incognita and Pristionchus pacificus, as well as the Caenorhabditis species C. brenneri, C. briggsae, C. japonica and C. remanei, and revealed that: (i Most of the C. elegans proteins responsible for uptake and spread of exogenously applied double stranded (dsRNA are absent from parasitic species, including RNAi-competent plant-nematodes; (ii The Argonautes (AGOs responsible for gene expression regulation in C. elegans are broadly conserved, unlike those recruited during the induction of RNAi by exogenous dsRNA; (iii Secondary Argonautes (SAGOs are poorly conserved, and the nuclear AGO NRDE-3 was not identified in any parasite; (iv All five Caenorhabditis spp. possess an expanded RNAi effector repertoire relative to the parasitic nematodes, consistent with the propensity for gene loss in nematode parasites; (v In spite of the quantitative differences in RNAi effector complements across nematode species, all displayed qualitatively similar coverage of functional protein groups. In summary, we could not identify RNAi effector deficiencies that associate with reduced susceptibility in parasitic nematodes. Indeed, similarities in the RNAi effector complements of RNAi refractory and competent nematode parasites support the broad applicability of this research

RNA-Seq reveals the molecular mechanism of trapping and killing of root-knot nematodes by nematode-trapping fungi.

Science.gov (United States)

Pandit, Ramesh; Patel, Reena; Patel, Namrata; Bhatt, Vaibhav; Joshi, Chaitanya; Singh, Pawan Kumar; Kunjadia, Anju

2017-04-01

Nematode-trapping fungi are well known for their inherent potential to trap and kill nematodes using specialized trapping devices. However, the molecular mechanisms underlying the trapping and subsequent processes are still unclear. Therefore, in this study, we examined differential genes expression in two nematode-trapping fungi after baiting with nematode extracts. In Arthrobotrys conoides, 809 transcripts associated with diverse functions such as signal transduction, morphogenesis, stress response and peroxisomal proteins, proteases, chitinases and genes involved in the host-pathogen interaction showed differential expression with fold change (>±1.5 fold) in the presence of nematode extract with FDR (p-value nematode-trapping fungi for its host. The findings illustrate the molecular mechanism of fungal parasitism in A. conoides which may be helpful in developing a potential biocontrol agent against parasitic nematodes.

'Candidatus pasteuria usgae' sp. nov., an obligate endoparasite of the phytoparasitic nematode Belonolaimus longicaudatus.

Science.gov (United States)

Giblin-Davis, R M; Williams, D S; Bekal, S; Dickson, D W; Brito, J A; Becker, J O; Preston, J F

2003-01-01

Taxonomically relevant characteristics of a fastidiously Gram-positive, obligately endoparasitic prokaryote (strain S-1) that uses the phytoparasitic sting nematode Belonolaimus longicaudatus as its host are reviewed. 16S rDNA sequence similarity (> or = 93%) confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans and corroborates morphological, morphometric and host range evidence suggesting a novel taxon. The 16S rDNA sequence of strain S-1 has greatest similarity (96%) to the 16S rDNA sequences of both Pasteuria penetrans from root-knot nematodes (Meloidogyne species) and the recently reported strain of Pasteuria isolated from the soybean cyst nematode Heterodera glycines. Because the obligately endoparasitic nature of prokaryotes in the genus Pasteuria prevents isolation of definitive type strains, strain S-1 is proposed as 'Candidatus Pasteuria usgae' sp. nov.

The reindeer abomasal nematode (Ostertagia gruehneri) is naturally transmitted to sheep when sharing pastures

DEFF Research Database (Denmark)

Manninen, Saana-Maaria; Thamsborg, Stig Milan; Laaksonen, Sauli

2014-01-01

The increasing number of sheep (Ovis aries) in northern Finland, often alternately corralled with winter-fed reindeer (Rangifer tarandus tarandus), creates potential for cross-infection of gastrointestinal nematodes. The aim of this study was to elucidate this possibility with 43 animals. Eleven...... reindeer and 8 sheep had shared a corral by turns, reindeer during winters, and sheep in summers. Another 12 reindeer had no known contact with sheep. Twelve sheep had no close contact to other ruminants. Both reindeer groups were free-ranging during summers. During slaughter in September to November, 2003......, abomasa and parts of intestines were collected. Gastrointestinal nematodes were counted and identified. The species found were the following: in reindeer, Ostertagia gruehneri/Ostertagia arctica, Mazamastrongylus dagestanica, Nematodirus tarandi, Nematodirella longissimespiculata and Bunostomum...

Nematode grazing promotes bacterial community dynamics in soil at the aggregate level.

Science.gov (United States)

Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo

2017-12-01

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.

Natural Transformation of Campylobacter jejuni Occurs Beyond Limits of Growth

Science.gov (United States)

Vegge, Christina S.; Brøndsted, Lone; Ligowska-Marzęta, Małgorzata; Ingmer, Hanne

2012-01-01

Campylobacter jejuni is a human bacterial pathogen. While poultry is considered to be a major source of food borne campylobacteriosis, C. jejuni is frequently found in the external environment, and water is another well-known source of human infections. Natural transformation is considered to be one of the main mechanisms for mediating transfer of genetic material and evolution of the organism. Given the diverse habitats of C. jejuni we set out to examine how environmental conditions and physiological processes affect natural transformation of C. jejuni. We show that the efficiency of transformation is correlated to the growth conditions, but more importantly that transformation occurs at growth-restrictive conditions as well as in the late stationary phase; hence revealing that growth per se is not required for C. jejuni to be competent. Yet, natural transformation of C. jejuni is an energy dependent process, that occurs in the absence of transcription but requires an active translational machinery. Moreover, we show the ATP dependent ClpP protease to be important for transformation, which possibly could be associated with reduced protein glycosylation in the ClpP mutant. In contrast, competence of C. jejuni was neither found to be involved in DNA repair following DNA damage nor to provide a growth benefit. Kinetic studies revealed that several transformation events occur per cell cycle indicating that natural transformation of C. jejuni is a highly efficient process. Thus, our findings suggest that horizontal gene transfer by natural transformation takes place in various habitats occupied by C. jejuni. PMID:23049803

Transmission of naturally occurring lymphoma in macaque monkeys.

OpenAIRE

Hunt, R D; Blake, B J; Chalifoux, L V; Sehgal, P K; King, N W; Letvin, N L

1983-01-01

Spontaneously occurring rhesus monkey lymphomas were transmitted into healthy rhesus monkeys by using tumor cell suspensions. The naturally arising tumors included an immunoblastic sarcoma and an undifferentiated lymphoma. Recipient animals developed undifferentiated lymphomas, poorly differentiated lymphomas, or parenchymal lymphoproliferative abnormalities suggestive of early lesions of lymphoma. Some of these animals developed such opportunistic infections as cytomegalovirus hepatitis and ...

Interspecific competition between entomopathogenic nematodes (Steinernema is modified by their bacterial symbionts (Xenorhabdus

Directory of Open Access Journals (Sweden)

Pages Sylvie

2006-09-01

Full Text Available Abstract Background Symbioses between invertebrates and prokaryotes are biological systems of particular interest in order to study the evolution of mutualism. The symbioses between the entomopathogenic nematodes Steinernema and their bacterial symbiont Xenorhabdus are very tractable model systems. Previous studies demonstrated (i a highly specialized relationship between each strain of nematodes and its naturally associated bacterial strain and (ii that mutualism plays a role in several important life history traits of each partner such as access to insect host resources, dispersal and protection against various biotic and abiotic factors. The goal of the present study was to address the question of the impact of Xenorhabdus symbionts on the progression and outcome of interspecific competition between individuals belonging to different Steinernema species. For this, we monitored experimental interspecific competition between (i two nematode species: S. carpocapsae and S. scapterisci and (ii their respective symbionts: X. nematophila and X. innexi within an experimental insect-host (Galleria mellonella. Three conditions of competition between nematodes were tested: (i infection of insects with aposymbiotic IJs (i.e. without symbiont of both species (ii infection of insects with aposymbiotic IJs of both species in presence of variable proportion of their two Xenorhabdus symbionts and (iii infection of insects with symbiotic IJs (i.e. naturally associated with their symbionts of both species. Results We found that both the progression and the outcome of interspecific competition between entomopathogenic nematodes were influenced by their bacterial symbionts. Thus, the results obtained with aposymbiotic nematodes were totally opposite to those obtained with symbiotic nematodes. Moreover, the experimental introduction of different ratios of Xenorhabdus symbionts in the insect-host during competition between Steinernema modified the proportion of

Naturally Occurring Anthraquinones: Chemistry and Therapeutic Potential in Autoimmune Diabetes

Directory of Open Access Journals (Sweden)

Shih-Chang Chien

2015-01-01

Full Text Available Anthraquinones are a class of aromatic compounds with a 9,10-dioxoanthracene core. So far, 79 naturally occurring anthraquinones have been identified which include emodin, physcion, cascarin, catenarin, and rhein. A large body of literature has demonstrated that the naturally occurring anthraquinones possess a broad spectrum of bioactivities, such as cathartic, anticancer, anti-inflammatory, antimicrobial, diuretic, vasorelaxing, and phytoestrogen activities, suggesting their possible clinical application in many diseases. Despite the advances that have been made in understanding the chemistry and biology of the anthraquinones in recent years, research into their mechanisms of action and therapeutic potential in autoimmune disorders is still at an early stage. In this paper, we briefly introduce the etiology of autoimmune diabetes, an autoimmune disorder that affects as many as 10 million worldwide, and the role of chemotaxis in autoimmune diabetes. We then outline the chemical structure and biological properties of the naturally occurring anthraquinones and their derivatives with an emphasis on recent findings about their immune regulation. We discuss the structure and activity relationship, mode of action, and therapeutic potential of the anthraquinones in autoimmune diabetes, including a new strategy for the use of the anthraquinones in autoimmune diabetes.

Deposits of naturally occurring radioactivity in production of oil and natural gas

International Nuclear Information System (INIS)

Strand, T.; Lysebo, I.; Kristensen, D.; Birovljev, A.

1997-01-01

Deposits of naturally occurring radioactive materials is an increasing problem in Norwegian oil and gas production. Activity concentration in solid-state samples and production water, and doses to workers involved in different operations off-shore, have been measured. The report also includes a discussion of different methods of monitoring and alternatives for final disposal of wastes. 154 refs

Content of naturally occurring radionuclides in samples taken from world historical sites

International Nuclear Information System (INIS)

Nikolic, J.; Jankovic, M.; Todorovic, D.; Sarap, N.

2011-01-01

This paper presents the results of the investigation of naturally occurring radionuclides content in different samples taken from the historical sites in Iran, China, Syria and Jordan. Samples contained different natural materials used in masonry, for making artefacts for personal use as well as water, sand and mud from the Dead sea. The aim was to ascertain the content of naturally occurring radionuclides, calculation of hazard indexes and their comparison to the values recommended and obtained in modern days materials [sr

Signaling in Parasitic Nematodes: Physicochemical Communication Between Host and Parasite and Endogenous Molecular Transduction Pathways Governing Worm Development and Survival.

Science.gov (United States)

Lok, James B

2016-12-01

Signaling or communication between host and parasite may occur over relatively long ranges to enable host finding and acquisition by infective parasitic nematode larvae. Innate behaviors in infective larvae transmitted from the soil that enhance the likelihood of host contact, such as negative geotaxis and hypermotility, are likely mediated by mechanoreception and neuromuscular signaling. Host cues such as vibration of the substratum, elevated temperature, exhaled CO 2 , and other volatile odorants are perceived by mechanosensory and chemosensory neurons of the amphidial complex. Beyond this, the molecular systems that transduce these external cues within the worm are unknown at this time. Overall, the signal transduction mechanisms that regulate switching between dauer and continuous reproductive development in Caenorhabditis elegans , and doubtless other free-living nematodes, have provided a useful framework for testing hypotheses about how the morphogenesis and development of infective parasitic nematode larvae and the lifespan of adult parasites are regulated. In C. elegans , four major signal transduction pathways, G protein-coupled receptor signaling, insulin/insulin-like growth factor signaling, TGFβ-like signaling and steroid-nuclear hormone receptor signaling govern the switch between dauer and continuous development and regulate adult lifespan. Parasitic nematodes appear to have conserved the functions of G-protein-coupled signaling, insulin-like signaling and steroid-nuclear hormone receptor signaling to regulate larval development before and during the infective process. By contrast, TGFβ-like signaling appears to have been adapted for some other function, perhaps modulation of the host immune response. Of the three signal transduction pathways that appear to regulate development in parasitic nematodes, steroid-nuclear hormone signaling is the most straightforward to manipulate with administered small molecules and may form the basis of new

Dispersal strategy of cyst nematodes (Heterodera arenaria) in the plant root zone of mobile dunes and consequences for emergence, survival and reproductive success

NARCIS (Netherlands)

Stoel, C.D.; Putten, van der W.H.

2006-01-01

Root-feeding nematodes may play an important role in generating spatial and temporal variation in natural plant communities, but little is known about the performance of the nematodes in the plant root zone. We studied the emergence, survival and reproductive success of the cyst nematode Heterodera

Dispersal strategy of cyst nematodes (Heterodera Arenaria) in the plant root zone of mobile dunes and consequences for emergence, survival and reproductive success

NARCIS (Netherlands)

Van der Stoel, C.D.; Van der Putten, W.H.

2006-01-01

Root-feeding nematodes may play an important role in generating spatial and temporal variation in natural plant communities, but little is known about the performance of the nematodes in the plant root zone. We studied the emergence, survival and reproductive success of the cyst nematode Heterodera

Nematode cholinergic pharmacology

International Nuclear Information System (INIS)

Segerberg, M.A.

1989-01-01

Nematode acetylcholine (ACh) receptors were characterized using both biochemical and electrophysiological techniques, including: (1) receptor binding studies in crude homogenates of the free-living nematode Caenorhabditis elegans and the parasitic nematode Ascaris lumbricoides with the high-affinity probe [ 3 H]N-methylscopolamine ([ 3 H]NMS) which binds to muscarinic receptors in many vertebrate and invertebrate tissues (2) measurement of depolarization and contraction induced by a variety of cholinergic agents, including N-methylscopolamine (NMS), in an innervated dorsal muscle strip preparation of Ascaris; (3) examination of the antagonistic actions of d-tubocurarine (dTC) and NMS at dorsal neuromuscular junction; (4) measurement of input resistance changes in Ascaris commissural motorneurons induced by ACh, dTC, NMS, pilocarpine and other cholinergic drugs

Relationship between Psidium species (Myrtaceae) by resistance gene analog markers: focus on nematode resistance.

Science.gov (United States)

Noia, L R; Tuler, A C; Ferreira, A; Ferreira, M F S

2017-03-16

Guava (Psidium guajava L.) crop is severely affected by the nematode Meloidogyne enterolobii. Native Psidium species have been reported as sources of resistance against this nematode. Knowledge on the molecular relationship between Psidium species based on plant resistance gene analogs (RGA) can be useful in the genetic breeding of guava for resistance to M. enterolobii. In this study, RGA markers from conserved domains, and structural features of plant R genes, were employed to characterize Psidium species and establish genetic proximity, with a focus on nematode resistance. SSR markers were also applied owing to their neutral nature, thus differing from RGA markers. For this, species reported as sources of resistance to M. enterolobii, such as P. cattleianum and P. friedrichsthalianum, as well as species occurring in the Atlantic Rainforest and susceptible genotypes, were investigated. In 10 evaluated Psidium species, high interspecific genetic variability was verified through RGA and SSR markers, with intraspecific variation in P. guajava higher with SSR, as was expected. Resistant species were clustered by RGA markers, and differential amplicons among genotypes resistant and susceptible to M. enterolobii were identified. Knowledge on the molecular relationships between Psidium species constitutes useful information for breeding of the guava tree, providing direction for hybridization and material for rootstocks. Additionally, the genetic relationship between native species, which have been little studied, and P. guajava were estimated by RGAs, which were confirmed as important markers for genetic diversity related to pathogen resistance.

Reference Material IAEA 434: Naturally Occurring Radionuclides in Phosphogypsum

International Nuclear Information System (INIS)

2010-01-01

Phosphogypsum is generated as a by-product of the phosphoric acid based fertilizer industry. The discharge of phosphogypsum on earth surface deposits is a potential source of enhanced natural radiation and heavy metals, and the resulting environmental impact should be considered carefully to ensure safety and compliance with environmental regulations. In addition, phosphogypsum can be used to make several building materials and it is used in agriculture as a conditioner to maintain soil productivity in areas where soils are poor and erode easily. A reliable determination of naturally occurring radionuclides in phosphogypsum is necessary to comply with the radiation protection and environmental regulations. The IAEA-434 will assist laboratories in the IAEA Member States in validating their analytical methods for the determination of naturally occurring radionuclides in phosphogypsum and to control the quality of the produced analytical results. Reference values for the massic activities and associated standard uncertainties were established for: Pb-210, Ra-226, Th-230, U-234 and U-238. During sample production and certification, the requirements for reference material production and certification as stated in ISO guides 34 and 35 were taken into account. This report summarizes the preparation and certification process

Small RNAs and extracellular vesicles in filarial nematodes: From nematode development to diagnostics.

Science.gov (United States)

Quintana, J F; Babayan, S A; Buck, A H

2017-02-01

Parasitic nematodes have evolved sophisticated mechanisms to communicate with their hosts in order to survive and successfully establish an infection. The transfer of RNA within extracellular vesicles (EVs) has recently been described as a mechanism that could contribute to this communication in filarial nematodes. It has been shown that these EVs are loaded with several types of RNAs, including microRNAs, leading to the hypothesis that parasites could actively use these molecules to manipulate host gene expression and to the exciting prospect that these pathways could result in new diagnostic and therapeutic strategies. Here, we review the literature on the diverse RNAi pathways that operate in nematodes and more specifically our current knowledge of extracellular RNA (exRNA) and EVs derived from filarial nematodes in vitro and within their hosts. We further detail some of the issues and questions related to the capacity of RNA-mediated communication to function in parasite-host interactions and the ability of exRNA to enable us to distinguish and detect different nematode parasites in their hosts. © 2016 The Authors. Parasite Immunology published by John Wiley & Sons Ltd.

On the noble gas isotopic fractionation in naturally occurring gases

International Nuclear Information System (INIS)

Marty, B.

1984-01-01

The isotopic composition of neon in the mantle is an important geochemical constraint on the formation of the earth and subsequent degassing. Some deviation of neon isotopic composition in natural gas and rock samples from the atmospheric value which can not be accounted for by the known nuclear process has been reported, and Nagao et al. interpreted the deviation as the result of mass fractionation in natural gas in Japan. The possible cause of such fractionation was investigated. Gaseous diffusion, such as (a) free-molecule diffusion, (b) mutual diffusion and (c) thermal diffusion, is able to cause isotopic fractionation. After the detailed consideration on these three diffusion processes, conclusion that free-molecule diffusion occurs only in very particular condition, and it is questionable that thermal diffusion occurs in nature, were obtained. (b) which means the interaction of two or more gases, is supposed to occur in nature, and is able to confirm experimentally. In mutual diffusion only, gas transfer is concerned, but other form of fractionation should not be neglected. In solid diffusion, gas is trapped by fine grained sedimentary rocks, and may be fractionated by adsorption and communication to exterior through minute channels. Underground water also works as noble gas reservoir. For example, when gas stream is in contact with water, continuous exchange is possible to take place at the interface of gas and liquid, which contributes to the fractionation. (Ishimitsu, A.)

Naturally occurring crystalline phases: analogues for radioactive waste forms

International Nuclear Information System (INIS)

Haaker, R.F.; Ewing, R.C.

1981-01-01

Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included

Naturally occurring crystalline phases: analogues for radioactive waste forms

Energy Technology Data Exchange (ETDEWEB)

Haaker, R.F.; Ewing, R.C.

1981-01-01

Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included.

Plant-parasitic nematodes in Hawaiian agriculture

Science.gov (United States)

Hawaii’s diverse and mild climate allows for the cultivation of many crops. The introduction of each crop plant brought along its associated nematode pests. These plant-parasitic nematodes became established and are now endemic to the islands. Plantation agriculture determined the major nematode ...

Regulation of naturally occurring radioactive materials in Australia

International Nuclear Information System (INIS)

Jeffries, C.; Akber, R.; Johnston, A.; Cassels, B.

2011-01-01

In order to promote uniformity between jurisdictions, the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has developed the National Directory for Radiation Protection, which is a regulatory framework that all Australian governments have agreed to adopt. There is a large and diverse range of industries involved in mining or mineral processing, and the production of fossil fuels in Australia. Enhanced levels of naturally occurring radionuclides can be associated with mineral extraction and processing, other industries (e.g. metal recycling) and some products (e.g. plasterboard). ARPANSA, in conjunction with industry and State regulators, has undertaken a review and assessment of naturally occurring radioactive material (NORM) management in Australian industries. This review has resulted in guidance on the management of NORM that will be included in the National Directory for Radiation Protection. The first NORM safety guide provides the framework for NORM management and addresses specific NORM issues in oil and gas production, bauxite, aluminium and phosphate industries. Over time further guidance material for other NORM-related industries will be developed. This presentation will provide an overview of the regulatory approach to managing NORM industries in Australia. (authors)

Regulation of naturally occurring radioactive materials in Australia.

Science.gov (United States)

Jeffries, Cameron; Akber, Riaz; Johnston, Andrew; Cassels, Brad

2011-07-01

In order to promote uniformity between jurisdictions, the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has developed the National Directory for Radiation Protection, which is a regulatory framework that all Australian governments have agreed to adopt. There is a large and diverse range of industries involved in mining or mineral processing, and the production of fossil fuels in Australia. Enhanced levels of naturally occurring radionuclides can be associated with mineral extraction and processing, other industries (e.g. metal recycling) and some products (e.g. plasterboard). ARPANSA, in conjunction with industry and State regulators, has undertaken a review and assessment of naturally occurring radioactive material (NORM) management in Australian industries. This review has resulted in guidance on the management of NORM that will be included in the National Directory for Radiation Protection. The first NORM safety guide provides the framework for NORM management and addresses specific NORM issues in oil and gas production, bauxite, aluminium and phosphate industries. Over time further guidance material for other NORM-related industries will be developed. This presentation will provide an overview of the regulatory approach to managing NORM industries in Australia.

Unraveling the intraguild competition between Oscheius spp. nematodes and entomopathogenic nematodes: Implications for their natural distribution in Swiss agricultural soils.

Science.gov (United States)

Campos-Herrera, Raquel; Půža, Vladimir; Jaffuel, Geoffrey; Blanco-Pérez, Rubén; Čepulytė-Rakauskienė, Rasa; Turlings, Ted C J

2015-11-01

Entomopathogenic nematodes (EPN) are excellent biological control agents to fight soil-dwelling insect pests. In a previous survey of agricultural soils of Switzerland, we found mixtures of free-living nematodes (FLN) in the genus Oscheius, which appeared to be in intense competition with EPN. As this may have important implications for the long-term persistence of EPN, we studied this intraguild competition in detail. We hypothesized that (i) Oscheius spp. isolates act as scavengers rather than entomopathogens, and (ii) cadavers with relatively small numbers of EPN are highly suitable resources for Oscheius spp. reproduction. To study this, we identified Oscheius spp. isolated from Swiss soils, quantified the outcome of EPN/Oscheius competition in laboratory experiments, developed species-specific primers and probe for quantitative real-time PCR, and evaluated their relative occurrence in the field in the context of the soil food web. Molecular analysis (ITS/D2D3) identified MG-67/MG-69 as Oscheius onirici and MG-68 as O. tipulae (Dolichura-group). Oscheius spp. indeed behaved as scavengers, reproducing in ∼64% of frozen-killed cadavers from controlled experiments. Mixed infection in the laboratory by Oscheius spp. with low (3 IJs) or high (20 IJs) initial EPN numbers revealed simultaneous reproduction in double-exposed cadavers which resulted in a substantial reduction in the number of EPN progeny from the cadaver. This effect depended on the number of EPN in the initial inoculum and differed by EPN species; Heterorhabditis megidis was better at overcoming competition. This study reveals Oscheius spp. as facultative kleptoparasites that compete with EPN for insect cadavers. Using real-time qPCR, we were able to accurately quantify this strong competition between FLN and EPN in cadavers that were recovered after soil baiting (∼86% cadavers with >50% FLN production). The severe competition within the host cadavers and the intense management of the soils in

Genetic identification of anisakid nematodes isolated from largehead hairtail (Trichiurus japonicus in Korea

Directory of Open Access Journals (Sweden)

Jeong-Ho Kim

2016-07-01

Full Text Available Abstract Background The nematode species belonging to genus Anisakis occur at their third larval stage in numerous marine teleost fish species worldwide and known to cause accidental human infection through the ingestion of raw or undercooked fish or squids. They may also draw the attention of consumers because of the visual impact of both alive and dead worms. Therefore, the information on their geographical distribution and clear species identification is important for epidemiological survey and further prevention of human infection. Results For identification of anisakid nematodes species isolated from largehead hairtail (Trichiurus japonicus, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP analysis of internal transcribed spacers of ribosomal DNA were conducted. Mitochondrial cytochrome c oxidase subunit 2 gene was also sequenced, and phylogenetic analysis was conducted. From the largehead hairtail (n = 9, 1259 nematodes were isolated in total. Most of the nematodes were found encapsulated throughout the viscera (56.2 %, 708/1259 or moving freely in the body cavity (41.5 %, 523/1259, and only 0.3 % (4/1259 was found in the muscles. By PCR-RFLP, three different nematode species were identified. Anisakis pegreffii was the most dominantly found (98.7 %, 1243/1259 from the largehead hairtail, occupying 98.7 % (699/708 of the nematodes in the mesenteries and 98.1 % (513/523 in the body cavity. Hybrid genotype (Anisakis simplex × A. pegreffii occupied 0.5 %, and Hysterothylacium sp. occupied 0.2 % of the nematodes isolated in this study. Conclusions The largehead hairtail may not significantly contribute accidental human infection of anisakid nematode third stage larvae because most of the nematodes were found from the viscera or body cavity, which are not consumed raw. But, a high prevalence of anisakid nematode larvae in the largehead hairtail is still in concern because they may raise food safety

Nematodes inhabit soils of forest and clear-cut areas

Science.gov (United States)

Alex L. Shigo; George Yelenosky

1960-01-01

Nematodes are present in all forest soils, but their effects on forest trees are not known. The known destructive nature of these worms on other woody crops suggests that they may also be involved in causing some of the unexplainable losses in vigor and mortality of forest trees.

Sex-specific lifespan and its evolution in nematodes.

Science.gov (United States)

Ancell, Henry; Pires-daSilva, Andre

2017-10-01

Differences between sexes of the same species in lifespan and aging rate are widespread. While the proximal and evolutionary causes of aging are well researched, the factors that contribute to sex differences in these traits have been less studied. The striking diversity of nematodes provides ample opportunity to study variation in sex-specific lifespan patterns associated with shifts in life history and mating strategy. Although the plasticity of these sex differences will make it challenging to generalize from invertebrate to vertebrate systems, studies in nematodes have enabled empirical evaluation of predictions regarding the evolution of lifespan. These studies have highlighted how natural and sexual selection can generate divergent patterns of lifespan if the sexes are subject to different rates or sources of mortality, or if trade-offs between complex traits and longevity are resolved differently in each sex. Here, we integrate evidence derived mainly from nematodes that addresses the molecular and evolutionary basis of sex-specific aging and lifespan. Ultimately, we hope to generate a clearer picture of current knowledge in this area, and also highlight the limitations of our understanding. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Anthelmintic effects of forage chicory against parasitic nematodes in cattle

DEFF Research Database (Denmark)

Pena-Espinoza, Miguel Angel; Williams, Andrew; Thamsborg, Stig Milan

BACKGROUND: Chicory (Cichorium intybus) has potential as a natural anthelmintic in livestock, however evidence of efficacy against cattle nematodes is lacking. Here, we investigated anthelmintic effects of chicory in stabled calves. METHODS: Jersey male calves (2-4 months) were stratified by live...

Naturally occuring radiation in the Nordic countries - recommendations

International Nuclear Information System (INIS)

1986-01-01

In the publication ''Report on the Applicability of International Radiation Protection Recommendations in the Nordic Countries'', published in 1976, the radiation protection authorities in Denmark, Finland, Iceland, Norway and Sweden expessed their agreement on the main principles of radiation protection. The general aspects of radiation protection were covered in the recommendations with the exception of exposure of the public from natural sources of radiation. In 1983 a working group published the report ''Naturally Occurring radiation in the Nordic Countries, - Levels'' in the Radiation Protection Information-Series from the Nordic countries. In that report the present knowledge of the population exposure from natural sources of external gamma-radiation and from radon and thoron daughters in air was reviewed as a basis for the development of the radiation protection recommendations for natural radiation. During preparation of these recommendations due account has also been taken of ICRP publication no. 39: ''Principles for Limiting Exposure of the Public to Natural Sources of Radiation'', which was published in 1984 and in which ICRP for the first time has issued more specific recommendations for natural sources. The recommendations may serve as a basis for more formal rules and regulations within each country, if this is seemed necessary. However, no attempt has been made to formulate identical rules for all the five countries since the exposure levels from natural sources, methods of application and the legal frameworks differ between the countries. (EG)

Identification of Angiostrongylus cantonensis and other nematodes using the SSU rDNA in Achatina fulica populations of Metro Manila.

Science.gov (United States)

Constantino-Santos, M A; Basiao, Z U; Wade, C M; Santos, B S; Fontanilla I, K C

2014-06-01

Angiostrongylus cantonensis is a parasitic nematode that causes eosinophilic meningitis in humans. Accidental infection occurs by consumption of contaminated intermediates, such as the giant African land snail, Achatina fulica. This study surveyed the presence of A. cantonensis juveniles in A. fulica populations from 12 sites in Metropolitan Manila, Philippines using the SSU rDNA. Fourteen distinct sequences from 226 nematodes were obtained; of these, two matched A. cantonensis and Ancylostoma caninum, respectively, with 100% identity. Exact identities of the remaining twelve sequences could not be determined due to low percent similarities. Of the sequenced nematodes, A. cantonensis occurred with the highest frequency (139 out of 226). Most of these (131 out of 139) were collected in just one area in Quezon City. Nematode infection of A. fulica in this area and two others from Makati and another area in Quezon City, respectively, were highest, combining for 95% of the total infection. Ancylostoma caninum, on the other hand, was detected in four different sites. A. caninum is a canine parasite, and this is the first report of the nematode in A. fulica. These results cause public health concerns as both A. cantonensis and A. caninum are zoonotic to humans.

Evaluation of Clonostachys rosea for Control of Plant-Parasitic Nematodes in Soil and in Roots of Carrot and Wheat.

Science.gov (United States)

Iqbal, Mudassir; Dubey, Mukesh; McEwan, Kerstin; Menzel, Uwe; Franko, Mikael Andersson; Viketoft, Maria; Jensen, Dan Funck; Karlsson, Magnus

2018-01-01

Biological control is a promising approach to reduce plant diseases caused by nematodes. We tested the effect of the fungus Clonostachys rosea strain IK726 inoculation on nematode community composition in a naturally nematode infested soil in a pot experiment, and the effect of C. rosea on plant health. The numbers of plant-parasitic nematode genera extracted from soil and plant roots decreased by 40 to 73% when C. rosea was applied, while genera of nonparasitic nematodes were not affected. Soil inoculation of C. rosea increased fresh shoot weight and shoot length of wheat plants by 20 and 24%, respectively, while only shoot dry weight increased by 48% in carrots. Light microscopy of in vitro C. rosea-nematode interactions did not reveal evidence of direct parasitism. However, culture filtrates of C. rosea growing in potato dextrose broth, malt extract broth and synthetic nutrient broth exhibited toxicity toward nematodes and immobilized 57, 62, and 100% of the nematodes, respectively, within 48 h. This study demonstrates that C. rosea can control plant-parasitic nematodes and thereby improve plant growth. The most likely mechanism responsible for the antagonism is antibiosis through production of nematicidal compounds, rather than direct parasitism.

Adsorption of fluoride ions onto naturally occurring earth materials ...

African Journals Online (AJOL)

Batch sorption system using two naturally occurring earth materials (EM) as adsorbents was investigated to remove fluoride ions from aqueous solution. The system variables studied include initial concentration of the sorbate, agitation time, adsorbent dose, pH, co-ions and temperature. The experimental data fitted well to ...

Conflict of interest between a nematode and a trematode in an amphipod host: Test of the "sabotage" hypothesis

Science.gov (United States)

Thomas, Frédéric; Fauchier, Jerome; Lafferty, Kevin D.

2002-01-01

Microphallus papillorobustus is a manipulative trematode that induces strong behavioural alterations in the gamaridean amphipod Gammarus insensibilis, making the amphipod more vulnerable to predation by aquatic birds (definitive hosts). Conversely, the sympatric nematodeGammarinema gammari uses Gammarus insensibilis as a habitat and a source of nutrition. We investigated the conflict of interest between these two parasite species by studying the consequences of mixed infection on amphipod behaviour associated with the trematode. In the field, some amphipods infected by the trematode did not display the altered behaviour. These normal amphipods also had more nematodes, suggesting that the nematode overpowered the manipulation of the trematode, a strategy that would prolong the nematode's life. We hypothesize that sabotage of the trematode by the nematode would be an adaptive strategy for the nematode consistent with recent speculation about co-operation and conflict in manipulative parasites. A behavioural test conducted in the laboratory from naturally infected amphipods yielded the same result. However, exposing amphipods to nematodes did not negate or decrease the manipulation exerted by the trematode. Similarly, experimental elimination of nematodes from amphipods did not permit trematodes to manipulate behaviour. These experimental data do not support the hypothesis that the negative association between nematodes and manipulation by the trematode is a result of the "sabotage" hypothesis.

Evolutionary history of nematodes associated with sweat bees.

Science.gov (United States)

McFrederick, Quinn S; Taylor, Douglas R

2013-03-01

Organisms that live in close association with other organisms make up a large part of the world's diversity. One driver of this diversity is the evolution of host-species specificity, which can occur via reproductive isolation following a host-switch or, given the correct circumstances, via cospeciation. In this study, we explored the diversity and evolutionary history of Acrostichus nematodes that are associated with halictid bees in North America. First, we conducted surveys of bees in Virginia, and found six halictid species that host Acrostichus. To test the hypothesis of cospeciation, we constructed phylogenetic hypotheses of Acrostichus based on three genes. We found Acrostichus puri and Acrostichus halicti to be species complexes comprising cryptic, host-specific species. Although several nodes in the host and symbiont phylogenies were congruent and tests for cospeciation were significant, the host's biogeography, the apparent patchiness of the association across the host's phylogeny, and the amount of evolution in the nematode sequence suggested a mixture of cospeciation, host switching, and extinction events instead of strict cospeciation. Cospeciation can explain the relationships between Ac. puri and its augochlorine hosts, but colonization of Halictus hosts is more likely than cospeciation. The nematodes are vertically transmitted, but sexual transmission is also likely. Both of these transmission modes may explain host-species specificity and congruent bee and nematode phylogenies. Additionally, all halictid hosts come from eusocial or socially polymorphic lineages, suggesting that sociality may be a factor in the suitability of hosts for Acrostichus. Copyright © 2012 Elsevier Inc. All rights reserved.

An improved method for generating axenic entomopathogenic nematodes.

Science.gov (United States)

Yadav, Shruti; Shokal, Upasana; Forst, Steven; Eleftherianos, Ioannis

2015-09-19

Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophila rpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.

Fungi associated with free-living soil nematodes in Turkey

Directory of Open Access Journals (Sweden)

Karabörklü Salih

2015-01-01

Full Text Available Free-living soil nematodes have successfully adapted world-wide to nearly all soil types from the highest to the lowest of elevations. In the current study, nematodes were isolated from soil samples and fungi associated with these free-living soil nematodes were determined. Large subunit (LSU rDNAs of nematode-associated fungi were amplified and sequenced to construct phylogenetic trees. Nematode-associated fungi were observed in six nematode strains belonging to Acrobeloides, Steinernema and Cephalobus genera in different habitats. Malassezia and Cladosporium fungal strains indicated an association with Acrobeloides and Cephalobus nematodes, while Alternaria strains demonstrated an association with the Steinernema strain. Interactions between fungi and free-living nematodes in soil are discussed. We suggest that nematodes act as vectors for fungi.

Windstorms as mediator of soil nematode community changes: Evidence from European spruce forest

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Renčo M.

2017-03-01

Full Text Available Nematode communities in a Norway spruce forest in High Tatra National Park, Slovakia were monitored for the period of several years (2006 and 2013. Unfortunately, in May 2014 natural windstorm damaged the forest. This disastrous event, together with preliminary obtained results allowed us to compare the direct impact of windstorm damage of forest habitat on soil nematode assemblages. The forest destruction by windstorm had a significant effect on the total nematode abundance, the abundance of omnivores and herbivores, as well as the nematode species diversity. The most dominant species, representing 55 % of the total nematode fauna, in the plot studied were Acrobeloides nanus followed by Malenchus exiguus, Filenchus vulgaris, Plectus communis, Plectus parvus and Tylencholaimus mirabilis. The abundance of bacterivorous signifi cantly increased after the windstorm, meanwhile the abundance of omnivores, fungivores, and herbivores ectoparasites and epidermal/root hair feeders showed an opposite trend. Of the evaluative indicators, Shannon species diversity (H’spp, maturity index (MI, maturity index 2-5 (MI2-5, sigma maturity index (ΣMI, enrichment index (EI and structure index (SI decreased significantly after windstorm. The EI and SI indexes characterized soil ecosystems before windstorm (2006 - 2013 as maturing with low or moderate disturbance, but soil ecosystems shortly after the windstorm (2014 were degraded and nutrient depleted. This also corresponded with graphical display of metabolic footprints characteristics of soil food web. Overall, the nematode communities differed significantly before and after forest damage. These results suggest the role of nematode communities as indicators of environment condition quality or its disruption.

Multiple-strand displacement and identification of single nucleotide polymorphisms as markers of genotypic variation of Pasteuria penetrans biotypes infecting root-knot nematodes.

Science.gov (United States)

Nong, Guang; Chow, Virginia; Schmidt, Liesbeth M; Dickson, Don W; Preston, James F

2007-08-01

Pasteuria species are endospore-forming obligate bacterial parasites of soil-inhabiting nematodes and water-inhabiting cladocerans, e.g. water fleas, and are closely related to Bacillus spp. by 16S rRNA gene sequence. As naturally occurring bacteria, biotypes of Pasteuria penetrans are attractive candidates for the biocontrol of various Meloidogyne spp. (root-knot nematodes). Failure to culture these bacteria outside their hosts has prevented isolation of genomic DNA in quantities sufficient for identification of genes associated with host recognition and virulence. We have applied multiple-strand displacement amplification (MDA) to generate DNA for comparative genomics of biotypes exhibiting different host preferences. Using the genome of Bacillus subtilis as a paradigm, MDA allowed quantitative detection and sequencing of 12 marker genes from 2000 cells. Meloidogyne spp. infected with P. penetrans P20 or B4 contained single nucleotide polymorphisms (SNPs) in the spoIIAB gene that did not change the amino acid sequence, or that substituted amino acids with similar chemical properties. Individual nematodes infected with P. penetrans P20 or B4 contained SNPs in the spoIIAB gene sequenced in MDA-generated products. Detection of SNPs in the spoIIAB gene in a nematode indicates infection by more than one genotype, supporting the need to sequence genomes of Pasteuria spp. derived from single spore isolates.

Detection of Naturally Occurring Gear and Bearing Faults in a Helicopter Drivetrain

Science.gov (United States)

2014-01-01

Detection of Naturally Occurring Gear and Bearing Faults in a Helicopter Drivetrain by Kelsen E. LaBerge, Eric C. Ames, and Brian D. Dykas...5066 ARL-TR-6795 January 2014 Detection of Naturally Occurring Gear and Bearing Faults in a Helicopter Drivetrain Kelsen E. LaBerge...ELEMENT NUMBER 6. AUTHOR(S) Kelsen E. LaBerge, Eric C. Ames, and Brian D. Dykas 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER

Naturally occurring radionuclides in pasture soil, feed ingredients and milk of dairy cattle

Energy Technology Data Exchange (ETDEWEB)

Turtiainen, T.; Kostiainen, E.; Solatie, D. [STUK-Radiation and Nuclear Safety Authority (Finland)

2014-07-01

Naturally occurring radionuclides are generally considered being respective part of the environment and hence no statutory monitoring of their levels are required in food products. Therefore, limited data are available on the naturally occurring radionuclides in food. Dairy products constitute a significant portion of Finnish diet (400-500 g/d) and hence it is reasonable to study radionuclide levels in milk in more detail. Contrary to caesium, strontium and iodine, few transfer coefficients are available in the literature for naturally occurring radionuclide transfer to cow's milk. The renaissance of mining industry in Finland has raised a question among the public about the baseline values of naturally occurring radionuclides in Finnish agricultural products. The objective of this study was to investigate naturally occurring radionuclides in the components of dairy cattle diet and milk and calculate their transfer to milk. This information is needed for regulating the permitted discharges to the environment and for setting up monitoring programs if any unplanned discharges are released. In modern dairy farming, cattle are fed a precise diet in order to maximize milk production and quality and to achieve cost-effectiveness. Therefore, several different components are found in dairy cattle's diet and pasture grass concentrations are not sufficient for calculating radionuclide transfer to cow's milk. In this study, we carried out comprehensive sampling at four dairy farms each representing different areas of natural radiation background. The pasture soils were characterized and measured for natural radioactivity. Samples were taken from cattle's total diet (including e.g. pasture grass, water, silage, mineral forage) and milk. Document available in abstract form only. (authors)

Learning by investing: evidence from a naturally occurring auction

Czech Academy of Sciences Publication Activity Database

Hanousek, Jan; Kočenda, Evžen

2011-01-01

Roč. 19, č. 1 (2011), s. 125-149 ISSN 0967-0750 R&D Projects: GA ČR GA402/09/1595; GA MŠk LC542 Institutional research plan: CEZ:MSM0021620846 Keywords : learning * naturally occurring auction * stock market Subject RIV: AH - Economics Impact factor: 0.679, year: 2011

Mechanisms of host seeking by parasitic nematodes.

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Gang, Spencer S; Hallem, Elissa A

2016-07-01

The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect more than one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries [1]. Parasitic nematodes of livestock and crops result in billions of dollars in losses each year [1]. Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration [1]. Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.

Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest.

Science.gov (United States)

Lambshead, P John D; Brown, Caroline J; Ferrero, Timothy J; Hawkins, Lawrence E; Smith, Craig R; Mitchell, Nicola J

2003-01-09

The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. The taxonomic composition (at family to genus level) of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone) could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described) of the group. However, nematode ecology is in dire need of further study.

Effects of midas® on nematodes in commercial floriculture production in Florida.

Science.gov (United States)

Kokalis-Burelle, Nancy; Rosskopf, Erin N; Albano, Joseph P; Holzinger, John

2010-03-01

Cut flower producers currently have limited options for nematode control. Four field trials were conducted in 2006 and 2007 to evaluate Midas® (iodomethane:chloropicrin 50:50) for control of root-knot nematodes (Meloidogyne arenaria) on Celosia argentea var. cristata in a commercial floriculture production field in southeastern Florida. Midas (224 kg/ha) was compared to methyl bromide:chloropicrin (98:2, 224 kg/ha), and an untreated control. Treatments were evaluated for effects on Meloidogyne arenaria J2 and free-living nematodes in soil through each season, and roots at the end of each season. Plant growth and root disease were also assessed. Population levels of nematodes isolated from soil were highly variable in all trials early in the season, and generally rebounded by harvest, sometimes to higher levels in fumigant treatments than in the untreated control. Although population levels of nematodes in soil were not significantly reduced during the growing season, nematodes in roots and galling at the end of the season were consistently reduced with both methyl bromide and Midas compared to the untreated control. Symptoms of phytotoxicity were observed in Midas treatments during the first year and were attributed to Fe toxicity. Fertilization was adjusted during the second year to investigate potential fumigant/fertilizer interactions. Interactions occurred at the end of the fourth trial between methyl bromide and fertilizers with respect to root-knot nematode J2 isolated from roots and galling. Fewer J2 were isolated from roots treated with a higher level of Fe (3.05%) in the form of Fe sucrate, and galling was reduced in methyl bromide treated plots treated with this fertilizer compared to Fe EDTA. Reduced galling was also seen with Midas in Fe sucrate fertilized plots compared to Fe EDTA. This research demonstrates the difficulty of reducing high root-knot nematode population levels in soil in subtropical conditions in production fields that have been

Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes.

Science.gov (United States)

Lee, Joon Ha; Dillman, Adler R; Hallem, Elissa A

2016-05-06

Entomopathogenic nematodes (EPNs) are lethal parasites of insects that are of interest as biocontrol agents for insect pests and disease vectors. Although EPNs have been successfully commercialized for pest control, their efficacy in the field is often inconsistent for reasons that remain elusive. EPN infective juveniles (IJs) actively search for hosts to infect using a diverse array of host-emitted odorants. Here we investigate whether their host-seeking behavior is subject to context-dependent modulation. We find that EPN IJs exhibit extreme plasticity of olfactory behavior as a function of cultivation temperature. Many odorants that are attractive for IJs grown at lower temperatures are repulsive for IJs grown at higher temperatures and vice versa. Temperature-induced changes in olfactory preferences occur gradually over the course of days to weeks and are reversible. Similar changes in olfactory behavior occur in some EPNs as a function of IJ age. EPNs also show temperature-dependent changes in their host-seeking strategy: IJs cultured at lower temperatures appear to more actively cruise for hosts than IJs cultured at higher temperatures. Furthermore, we find that the skin-penetrating rat parasite Strongyloides ratti also shows temperature-dependent changes in olfactory behavior, demonstrating that such changes occur in mammalian-parasitic nematodes. IJs are developmentally arrested and long-lived, often surviving in the environment through multiple seasonal temperature changes. Temperature-dependent modulation of behavior may enable IJs to optimize host seeking in response to changing environmental conditions, and may play a previously unrecognized role in shaping the interactions of both beneficial and harmful parasitic nematodes with their hosts.

An Update on Antitumor Activity of Naturally Occurring Chalcones

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En-Hui Zhang

2013-01-01

Full Text Available Chalcones, which have characteristic 1,3-diaryl-2-propen-1-one skeleton, are mainly produced in roots, rhizomes, heartwood, leaves, and seeds of genera Angelica, Sophora, Glycyrrhiza, Humulus, Scutellaria, Parartocarpus, Ficus, Dorstenia, Morus, Artocarpus, and so forth. They have become of interest in the research and development of natural antitumor agents over the past decades due to their broad range of mechanisms including anti-initiation, induction of apoptosis, antiproliferation, antimetastasis, antiangiogenesis, and so forth. This review summarizes the studies on the antitumor activity of naturally occurring chalcones and their underlying mechanisms in detail during the past decades.

The effects of naturally occurring impurities in rock salt

Indian Academy of Sciences (India)

In this paper we investigate the effect that naturally occurring impurities in salt mines have both on effective permittivity of the medium and on radio wave propagation at ∼200 MHz. The effective permittivity is determined based on the dielectric properties of salt and the characteristics of the main impurities. We conclude that ...

Efficacy of Doramectin Via Intramuscular Injection in Gastrointestinal Nematodes in Horses

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Yonairo Manuel Herrera Benavides

2015-05-01

Full Text Available This research aimed to test the effectiveness of doramectin by intramuscular administration against nematodes of horses, as it is evacuated, observed in the reduction in egg counts per gram of feces (epg. To this end, six donkeys and ten mestizo horses of different sexes and ages were used, all naturally infected with gastrointestinal nematodes. Animals were randomly divided into two groups: 1 (control, three donkeys and four horses that didn’t receive anthelmintic treatment; and 2 (treated, three donkeys and six horses treated with doramectin at a dose of 0.2 mg/kg by intramuscular administration, single dose, applied on the neck. At days 5, 12, 16, 24, 34, 41, 47, 56, 60 and 140 post-treatment all animals were subjected to stool tests, allowing to define epg values by McMaster technique. The results determined that doramectin by intramuscular administration was highly effective in controlling nematodes in field conditions and in animals subjected to continual reinfestation.

Nematode communities in sediments of the Kermadec Trench, Southwest Pacific Ocean

Science.gov (United States)

Leduc, Daniel; Rowden, Ashley A.

2018-04-01

Hadal trenches are characterized by environmental conditions not found in any other deep-sea environment, such as steep topography and periodic disturbance by turbidity flows, which are likely responsible for the distinct nature of benthic communities of hadal trenches relative to those of the abyssal plain. Nematodes are the most abundant metazoans in the deep-sea benthos, but it is not yet clear if different trenches host distinct nematode communities, and no data are yet available on the communities of most trenches, including the Kermadec Trench in the Southwest Pacific. Quantitative core samples from the seafloor of the Kermadec Trench were recently obtained from four sites at 6000-9000 m depth which allowed for analyses of meiofauna, and nematodes in particular, for the first time. Nematode community and trophic structure was also compared with other trenches using published data. There was a bathymetric gradient in meiofauna abundance, biomass, and community structure within the Kermadec Trench, but patterns for species richness were ambiguous depending on which metric was used. There was a change in community structure from shallow to deep sites, as well as a consistent change in community structure from the upper sediment layers to the deeper sediment layers across the four sites. These patterns are most likely explained by variation in food availability within the trench, and related to trench topography. Together, deposit and microbial feeders represented 48-92% of total nematode abundance in the samples, which suggests that fine organic detritus and bacteria are major food sources. The relatively high abundance of epigrowth feeders at the 6000 and 9000 m sites (38% and 31%, respectively) indicates that relatively freshly settled microalgal cells represent another important food source at these sites. We found a significant difference in species community structure between the Kermadec and Tonga trenches, which was due to both the presence/absence of

NGT-3D: a simple nematode cultivation system to study Caenorhabditis elegans biology in 3D

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Tong Young Lee

2016-04-01

Full Text Available The nematode Caenorhabditis elegans is one of the premier experimental model organisms today. In the laboratory, they display characteristic development, fertility, and behaviors in a two dimensional habitat. In nature, however, C. elegans is found in three dimensional environments such as rotting fruit. To investigate the biology of C. elegans in a 3D controlled environment we designed a nematode cultivation habitat which we term the nematode growth tube or NGT-3D. NGT-3D allows for the growth of both nematodes and the bacteria they consume. Worms show comparable rates of growth, reproduction and lifespan when bacterial colonies in the 3D matrix are abundant. However, when bacteria are sparse, growth and brood size fail to reach levels observed in standard 2D plates. Using NGT-3D we observe drastic deficits in fertility in a sensory mutant in 3D compared to 2D, and this defect was likely due to an inability to locate bacteria. Overall, NGT-3D will sharpen our understanding of nematode biology and allow scientists to investigate questions of nematode ecology and evolutionary fitness in the laboratory.

Susceptibility of Dalotia coriaria (Kraatz (Coleoptera: Staphylinidae to Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae and Steinernematidae

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Joseph Tourtois

2015-03-01

Full Text Available Dalotia coriaria (Kraatz (Coleoptera: Staphylinidae and entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae are two soil-dwelling biological control agents used to manage western flower thrips, Frankliniella occidentalis (Pergande (Thysanoptera: Thripidae and fungus gnats Bradysis spp. (Diptera: Sciaridae in glasshouses. Growers often use multiple natural enemies to achieve economic control, but knowledge of interactions among natural enemies is lacking. We conducted a laboratory bioassay to test the pathogenicity of four commercially available nematode species—Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhbditidae, Steinernema carpocapsae (Weiser (Rhabditida: Steinernematidae, S. feltiae (Filipjev, and S. riobrave Cabanillas et al.—to third instar and adult D. coriaria. Third instars were three times more susceptible than the adults to the entomopathogenic nematodes. Mortality for D. coriaria adults and third instars treated with S. feltiae and H. bacteriophora was lower than the mortality for D. coriaria adults and third instars treated with S. carpocapsae and S. riobrave. Neither infective juvenile foraging behavior nor size correlates with D. coriaria mortality. Dalotia coriaria appears to be most likely compatible with applications of S. feltiae and H. bacteriophora.

Entomopathogenic nematodes for the biocontrol of ticks.

Science.gov (United States)

Samish, M; Glazer, I

2001-08-01

Entomopathogenic steinemematid and heterorhabditid nematodes are increasingly used to control insect pests of economically important crops. Laboratory and field simulation trials show that ticks are also susceptible to these nematodes. The authors review the potential of entomogenous nematodes for the control of ticks.

Nematode diversity, abundance and community structure 50 years after the formation of the volcanic island of Surtsey

Science.gov (United States)

Ilieva-Makulec, K.; Bjarnadottir, B.; Sigurdsson, B. D.

2014-10-01

The soil nematode fauna can give important insights into soil development and other habitat changes that occur during primary succession. We investigated the generic composition, density, distribution and community structure of nematodes 50 years after the formation of a pristine volcanic island, Surtsey, Iceland. Part of the island has received additional nutrient inputs from seagulls breeding there since 1985, while the reminder has been much less affected and is at present found at a different successional sere. In total, 25 genera of nematodes were identified, of which 14 were reported on Surtsey for the first time. Nematode communities were more diverse in the more infertile area outside the gull colony, where 24 genera were found, compared to 18 inside. The trophic structure of the nematode communities showed relatively higher abundance of fungal feeders in the infertile areas, but relatively more bacterial- and plant-feeders inside the colony. Nematode abundance in surface soil was, however, significantly higher within the gull colony, with 16.7 ind. cm-2 compared to 3.6 ind. cm-2 outside. A multivariate analysis indicated that the nematode abundance and distribution on Surtsey were most strongly related to the soil C : N ratio, soil acidity, plant cover and biomass, soil temperature and soil depth.

Epidemiology and effects of gastrointestinal nematode infection on milk productions of dairy ewes

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Suarez V.H.

2009-06-01

Full Text Available 66 Pampinta breed ewes were studied during milking to evaluate the infection and the effect of gastrointestinal nematode on milk production sheep system. Naturally infected ewes on pasture were randomly allocated to two groups: TG, suppressively treated group every four weeks with levamisole and UG, untreated group. Faecal nematode egg counts and larval differentiation were conducted monthly. Successive groups of worm free tracer lambs were grazed with ewes and then slaughtered for worm counts. Test-day milk yield of individual ewes was recorded and ewe machine-milking period length (MPL were estimated. Faecal egg counts and tracer nematode numbers increased towards midsummer and declined sharply toward the end of the study. TG (188.0 ± 60 liters produced more (p < 0.066 milk liters than UG (171.9 ± 52.2 and TG had significantly more extended (p < 0.041 MPL than those of UG. The present study showed that dairy sheep were negatively affected by worms, even when exposed to short periods of high acute nematode (mainly Haemonchus contortus infection.

Top 10 plant-parasitic nematodes in molecular plant pathology.

Science.gov (United States)

Jones, John T; Haegeman, Annelies; Danchin, Etienne G J; Gaur, Hari S; Helder, Johannes; Jones, Michael G K; Kikuchi, Taisei; Manzanilla-López, Rosa; Palomares-Rius, Juan E; Wesemael, Wim M L; Perry, Roland N

2013-12-01

The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a 'top 10' list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly. © 2013 BSPP AND JOHN WILEY & SONS LTD.

Bioassay of naturally occurring allelochemicals for phytotoxicity.

Science.gov (United States)

Leather, G R; Einhellig, F A

1988-10-01

The bioassay has been one of the most widely used tests to demonstrate allelopathic activity. Often, claims that a particular plant species inhibits the growth of another are based entirely on the seed germination response to solvent extracts of the suspected allelopathic plant; few of these tests are of value in demonstrating allelopathy under natural conditions. The veracity of the bioassay for evaluating naturally occurring compounds for phytotoxicity depends upon the physiological and biochemical response capacity of the bioassay organism and the mechanism(s) of action of the allelochemicals. The possibility that more than one allelochemical, acting in concert at very low concentrations, may be responsible for an observed allelopathic effect makes it imperative that bioassays be extremely sensitive to chemical growth perturbation agents. Among the many measures of phytotoxicity of allelochemicals, the inhibition (or stimulation) of seed germination, radicle elongation, and/or seedling growth have been the parameters of choice for most investigations. Few of these assays have been selected with the view towards the possible mechanism of the allelopathic effect.

Development of the system nematode, Ditylenchus Dipsaci (Kuehn) Filipjev, and the potato tuber nematode, D. Destructor thore, after gamma irradiation

International Nuclear Information System (INIS)

Ignatowicz, S.; Karnkowski, W.

1996-01-01

Juvenile and adult nematodes emerged from onion and garlic samples on the 3 rd week after irradiation with doses up to 0.5 kGy and from potato treated with doses up to 2.0 kGy. However, irradiation of onion infected with Ditylenchus dipsaci caused the inhibition of the development and growth of juvenile nematodes to mature forms. Doses of gamma radiation ranging from 0.1 to 0.5 kGy had only a slight effect, if any, on the development and growth of D. dipsaci nematodes infecting garlic, but they increased juvenile mortality. Gamma radiation at doses up to 2.0 kGy induced increased mortality of nematode juveniles of the potato tuber nematode, D. destructor but less so inhibited their development to mature forms. Nematodes were found to be resistant to irradiation treatment. Therefore the use of gamma irradiation for nematode disinfestation of agricultural products seems to be impractical, if the aim of the treatment is to kill these pests within a few weeks. The level of radiation required to kill nematodes in infected plants would damage plant tissues so that the further storage of vegetables will be impossible. (author). 22 refs, 3 figs, 2 tabs

Plant nematodes in South Africa. 11. Checklist of plant nematodes of the protected areas of KwaZulu-Natal

Directory of Open Access Journals (Sweden)

Mariette Marais

2013-03-01

Full Text Available Nematodes are some of the most abundant soil organisms and are an essential part of soil ecology. These organisms are used as indicator organisms and can be linked to soil health. Biological collections contain vast amounts of data, with the National Collection of Nematodes housed at the Plant Protection Research Institute, Agricultural Research Council being no different. During the digitising of the collection a number of unpublished records of plant nematodes reported from protected areas in KwaZulu-Natal were found in the South African Plant-Parasitic Nematode Survey database. A total of 222 plant nematode species belonging to 39 genera were reported from the province, with only 94 of these species reported from the protected areas and 172 and 159 species reported from uncultivated (outside the protected areas and cultivated areas, respectively. Only nine species, Criconema silvum, Criconema talanum, Helicotylenchus marethae, Ogma dracomontanum, Ogma louisi, Ogma ueckermanni, Paralongidorus deborae, Trichodorus rinae and Xiphinemella marindae were described from protected areas, whilst O. dracomontanum, P. deborae and T. rinae were subsequently also reported from other provinces. Conservation implications: A higher degree of diversity of nematodes was observed in the unprotected areas of the province. The observation suggests that nematode fauna, and by implication also other invertebrates, are not adequately protected.

Plant nematodes in South Africa. 11. Checklist of plant nematodes of the protected areas of KwaZulu-Natal

Directory of Open Access Journals (Sweden)

Mariette Marais

2013-02-01

Full Text Available Nematodes are some of the most abundant soil organisms and are an essential part of soil ecology. These organisms are used as indicator organisms and can be linked to soil health. Biological collections contain vast amounts of data, with the National Collection of Nematodes housed at the Plant Protection Research Institute, Agricultural Research Council being no different. During the digitising of the collection a number of unpublished records of plant nematodes reported from protected areas in KwaZulu-Natal were found in the South African Plant-Parasitic Nematode Survey database. A total of 222 plant nematode species belonging to 39 genera were reported from the province, with only 94 of these species reported from the protected areas and 172 and 159 species reported from uncultivated (outside the protected areas and cultivated areas, respectively. Only nine species, Criconema silvum, Criconema talanum, Helicotylenchus marethae, Ogma dracomontanum, Ogma louisi, Ogma ueckermanni, Paralongidorus deborae, Trichodorus rinae and Xiphinemella marindae were described from protected areas, whilst O. dracomontanum, P. deborae and T. rinae were subsequently also reported from other provinces. Conservation implications: A higher degree of diversity of nematodes was observed in the unprotected areas of the province. The observation suggests that nematode fauna, and by implication also other invertebrates, are not adequately protected.

Radiation Effects on Nematodes: Results from IML-1 Esperiments

Science.gov (United States)

Nelson, G. A.; Schubert, W. W.; Kazarians, G. A.; Righards, G. F.; Benton, E. V; Benton, E. R.; Henke, R.

1993-01-01

The nematode Caenorhabditis elegans was exposed to natural space radiation using the ESA Biorack facility aboard Spacelab on International Microgravity Laboratory 1, STS-42. For the major experimental objective dormant animals were suspended in buffer or on agar or immobilized next to CR-39 plactic nuclear track detectors to correlate fluence of HZE particles with genetic events.

Integrated Metabolomics and Morphogenesis Reveal Volatile Signaling of the Nematode-Trapping Fungus Arthrobotrys oligospora.

Science.gov (United States)

Wang, Bai-Le; Chen, Yong-Hong; He, Jia-Ning; Xue, Hua-Xi; Yan, Ni; Zeng, Zhi-Jun; Bennett, Joan W; Zhang, Ke-Qin; Niu, Xue-Mei

2018-05-01

The adjustment of metabolic patterns is fundamental to fungal biology and plays vital roles in adaptation to diverse ecological challenges. Nematode-trapping fungi can switch their lifestyle from saprophytic to pathogenic by developing specific trapping devices induced by nematodes to infect their prey as a response to nutrient depletion in nature. However, the chemical identity of the specific fungal metabolites used during the switch remains poorly understood. We hypothesized that these important signal molecules might be volatile in nature. Gas chromatography-mass spectrometry was used to carry out comparative analysis of fungal metabolomics during the saprophytic and pathogenic lifestyles of the model species Arthrobotrys oligospora Two media commonly used in research on this species, cornmeal agar (CMA) and potato dextrose agar (PDA), were chosen for use in this study. The fungus produced a small group of volatile furanone and pyrone metabolites that were associated with the switch from the saprophytic to the pathogenic stage. A. oligospora fungi grown on CMA tended to produce more traps and employ attractive furanones to improve the utilization of traps, while fungi grown on PDA developed fewer traps and used nematode-toxic furanone metabolites to compensate for insufficient traps. Another volatile pyrone metabolite, maltol, was identified as a morphological regulator for enhancing trap formation. Deletion of the gene AOL_s00079g496 in A. oligospora led to increased amounts of the furanone attractant (2-fold) in mutants and enhanced the attractive activity (1.5-fold) of the fungus, while it resulted in decreased trap formation. This investigation provides new insights regarding the comprehensive tactics of fungal adaptation to environmental stress, integrating both morphological and metabolomic mechanisms. IMPORTANCE Nematode-trapping fungi are a unique group of soil-living fungi that can switch from the saprophytic to the pathogenic lifestyle once they come

The bacterial community of entomophilic nematodes and host beetles.

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Koneru, Sneha L; Salinas, Heilly; Flores, Gilberto E; Hong, Ray L

2016-05-01

Insects form the most species-rich lineage of Eukaryotes and each is a potential host for organisms from multiple phyla, including fungi, protozoa, mites, bacteria and nematodes. In particular, beetles are known to be associated with distinct bacterial communities and entomophilic nematodes. While entomopathogenic nematodes require symbiotic bacteria to kill and reproduce inside their insect hosts, the microbial ecology that facilitates other types of nematode-insect associations is largely unknown. To illuminate detailed patterns of the tritrophic beetle-nematode-bacteria relationship, we surveyed the nematode infestation profiles of scarab beetles in the greater Los Angeles area over a five-year period and found distinct nematode infestation patterns for certain beetle hosts. Over a single season, we characterized the bacterial communities of beetles and their associated nematodes using high-throughput sequencing of the 16S rRNA gene. We found significant differences in bacterial community composition among the five prevalent beetle host species, independent of geographical origin. Anaerobes Synergistaceae and sulphate-reducing Desulfovibrionaceae were most abundant in Amblonoxia beetles, while Enterobacteriaceae and Lachnospiraceae were common in Cyclocephala beetles. Unlike entomopathogenic nematodes that carry bacterial symbionts, insect-associated nematodes do not alter the beetles' native bacterial communities, nor do their microbiomes differ according to nematode or beetle host species. The conservation of Diplogastrid nematodes associations with Melolonthinae beetles and sulphate-reducing bacteria suggests a possible link between beetle-bacterial communities and their associated nematodes. Our results establish a starting point towards understanding the dynamic interactions between soil macroinvertebrates and their microbiota in a highly accessible urban environment. © 2016 John Wiley & Sons Ltd.

Altered dopamine signaling in naturally occurring maternal neglect.

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Stephen C Gammie

2008-04-01

occurring neglect and that MaD1 mice are a useful model for understanding the basis of naturally occurring neglect.

Exploitation of FTA cartridges for the sampling, long-term storage, and DNA-based analyses of plant-parasitic nematodes.

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Marek, Martin; Zouhar, Miloslav; Douda, Ondřej; Maňasová, Marie; Ryšánek, Pavel

2014-03-01

The use of DNA-based analyses in molecular plant nematology research has dramatically increased over recent decades. Therefore, the development and adaptation of simple, robust, and cost-effective DNA purification procedures are required to address these contemporary challenges. The solid-phase-based approach developed by Flinders Technology Associates (FTA) has been shown to be a powerful technology for the preparation of DNA from different biological materials, including blood, saliva, plant tissues, and various human and plant microbial pathogens. In this work, we demonstrate, for the first time, that this FTA-based technology is a valuable, low-cost, and time-saving approach for the sampling, long-term archiving, and molecular analysis of plant-parasitic nematodes. Despite the complex structure and anatomical organization of the multicellular bodies of nematodes, we report the successful and reliable DNA-based analysis of nematode high-copy and low-copy genes using the FTA technology. This was achieved by applying nematodes to the FTA cards either in the form of a suspension of individuals, as intact or pestle-crushed nematodes, or by the direct mechanical printing of nematode-infested plant tissues. We further demonstrate that the FTA method is also suitable for the so-called "one-nematode-assay", in which the target DNA is typically analyzed from a single individual nematode. More surprisingly, a time-course experiment showed that nematode DNA can be detected specifically in the FTA-captured samples many years after initial sampling occurs. Collectively, our data clearly demonstrate the applicability and the robustness of this FTA-based approach for molecular research and diagnostics concerning phytonematodes; this research includes economically important species such as the stem nematode (Ditylenchus dipsaci), the sugar beet nematode (Heterodera schachtii), and the Northern root-knot nematode (Meloidogyne hapla).

Naturally occurring BRCA2 alternative mRNA splicing events in clinically relevant samples

DEFF Research Database (Denmark)

Fackenthal, James D; Yoshimatsu, Toshio; Zhang, Bifeng

2016-01-01

patterns and thereby disrupt gene function. mRNA analyses are therefore among the tests used to interpret the clinical significance of some genetic variants. However, these could be confounded by the appearance of naturally occurring alternative transcripts unrelated to germline sequence variation...... to characterise the spectrum of naturally occurring BRCA2 mRNA alternate-splicing events. METHODS: mRNA was prepared from several blood and breast tissue-derived cells and cell lines by contributing ENIGMA laboratories. cDNA representing BRCA2 alternate splice sites was amplified and visualised using capillary...... or agarose gel electrophoresis, followed by sequencing. RESULTS: We demonstrate the existence of 24 different BRCA2 mRNA alternate-splicing events in lymphoblastoid cell lines and both breast cancer and non-cancerous breast cell lines. CONCLUSIONS: These naturally occurring alternate-splicing events...

Biocontrol of ticks by entomopathogenic nematodes. Research update.

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Samish, M; Alekseev, E; Glazer, I

2000-01-01

Entomopathogenic nematodes (EPNs) are lethal to ticks even though they do not use their normal propagation cycle within tick cadavers. The tick Boophilus annulatus was found to be far more susceptible to EPNs than Hyalomma excavatum, Rhipicephalus bursa, or Rhipicephalus sanguineus. Ticks seem to be less susceptible to nematodes when feeding on a host. Preimaginal tick stages were less susceptible to nematodes than adult ticks. The mortality rate of unfed females was highest, followed by unfed males, and engorged females. The virulence of nematodes to ticks varied greatly among different nematode strains. In most cases, the Heterorhabditis sp. strains were the most virulent strains tested in petri dishes. In buckets containing sandy soil sprayed with 50 nematodes/cm2 and engorged B. annulatus females, the LT50 of the ticks was less than five days. The addition of manure to soil or a manure extract to petri dishes reduced nematode virulence. Since ticks spend most of their life cycle in the upper humid layer of the ground, and many nematode strains share this same ecological niche, the use of EPNs for biocontrol of ticks appears promising.

Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest

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Hawkins Lawrence E

2003-01-01

Full Text Available Abstract Background The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. Results The taxonomic composition (at family to genus level of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. Conclusion The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described of the group. However, nematode ecology is in dire need of further study.

Nematode neuropeptides as transgenic nematicides.

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Neil D Warnock

2017-02-01

Full Text Available Plant parasitic nematodes (PPNs seriously threaten global food security. Conventionally an integrated approach to PPN management has relied heavily on carbamate, organophosphate and fumigant nematicides which are now being withdrawn over environmental health and safety concerns. This progressive withdrawal has left a significant shortcoming in our ability to manage these economically important parasites, and highlights the need for novel and robust control methods. Nematodes can assimilate exogenous peptides through retrograde transport along the chemosensory amphid neurons. Peptides can accumulate within cells of the central nerve ring and can elicit physiological effects when released to interact with receptors on adjoining cells. We have profiled bioactive neuropeptides from the neuropeptide-like protein (NLP family of PPNs as novel nematicides, and have identified numerous discrete NLPs that negatively impact chemosensation, host invasion and stylet thrusting of the root knot nematode Meloidogyne incognita and the potato cyst nematode Globodera pallida. Transgenic secretion of these peptides from the rhizobacterium, Bacillus subtilis, and the terrestrial microalgae Chlamydomonas reinhardtii reduce tomato infection levels by up to 90% when compared with controls. These data pave the way for the exploitation of nematode neuropeptides as a novel class of plant protective nematicide, using novel non-food transgenic delivery systems which could be deployed on farmer-preferred cultivars.

Interspecific nematode signals regulate dispersal behavior.

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Fatma Kaplan

Full Text Available Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2 of plant parasitic Meloidogyne spp. and infective juveniles (IJs of entomopathogenic nematodes (EPN, e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9. A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9 and C. elegans (ascr#2 dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

Unexpected variation in neuroanatomy among diverse nematode species

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Ziduan eHan

2016-01-01

Full Text Available Nematodes are considered excellent models for understanding fundamental aspects of neuron function. However, nematodes are less frequently used as models for examining the evolution of nervous systems. While the habitats and behaviors of nematodes are diverse, the neuroanatomy of nematodes is often considered highly conserved. A small number of nematode species greatly influences our understanding of nematode neurobiology. The free-living species Caenorhabditis elegans and, to a lesser extent, the mammalian gastrointestinal parasite Ascaris suum are, historically, the primary sources of knowledge regarding nematode neurobiology. Despite differences in size and habitat, C. elegans and Ascaris suum share a surprisingly similar neuroanatomy. Here, we examined species across several clades in the phylum Nematoda and show that there is a surprising degree of neuroanatomical variation both within and among nematode clades when compared to C. elegans and Ascaris. We found variation in the numbers of neurons in the ventral nerve cord and dye-filling pattern of sensory neurons. For example, we found that Pristionchus pacificus, a bacterial feeding species used for comparative developmental research, had 20% fewer ventral cord neurons compared to C. elegans. Steinernema carpocapse, an insect-parasitic nematode capable of jumping behavior, had 40% more ventral cord neurons than C. elegans. Interestingly, the non-jumping congeneric nematode, S. glaseri showed an identical number of ventral cord neurons as S. carpocapsae. There was also variability in the timing of neurodevelopment of the ventral cord with two of five species that hatch as second-stage juveniles showing delayed neurodevelopment. We also found unexpected variation in the dye-filling of sensory neurons among examined species. Again, sensory neuron dye-filling pattern did not strictly correlate with phylogeny. Our results demonstrate that variation in nematode neuroanatomy is more prevalent

Entomopathogenic nematode food webs in an ancient, mining pollution gradient in Spain.

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Campos-Herrera, Raquel; Rodríguez Martín, José Antonio; Escuer, Miguel; García-González, María Teresa; Duncan, Larry W; Gutiérrez, Carmen

2016-12-01

Mining activities pollute the environment with by-products that cause unpredictable impacts in surrounding areas. Cartagena-La Unión mine (Southeastern-Spain) was active for >2500years. Despite its closure in 1991, high concentrations of metals and waste residues remain in this area. A previous study using nematodes suggested that high lead content diminished soil biodiversity. However, the effects of mine pollution on specific ecosystem services remain unknown. Entomopathogenic nematodes (EPN) play a major role in the biocontrol of insect pests. Because EPNs are widespread throughout the world, we speculated that EPNs would be present in the mined areas, but at increased incidence with distance from the pollution focus. We predicted that the natural enemies of nematodes would follow a similar spatial pattern. We used qPCR techniques to measure abundance of five EPN species, five nematophagous fungi species, two bacterial ectoparasites of EPNs and one group of free-living nematodes that compete for the insect-cadaver. The study comprised 193 soil samples taken from mining sites, natural areas and agricultural fields. The highest concentrations of iron and zinc were detected in the mined area as was previously described for lead, cadmium and nickel. Molecular tools detected very low numbers of EPNs in samples found to be negative by insect-baiting, demonstrating the importance of the approach. EPNs were detected at low numbers in 13% of the localities, without relationship to heavy-metal concentrations. Only Acrobeloides-group nematodes were inversely related to the pollution gradient. Factors associated with agricultural areas explained 98.35% of the biotic variability, including EPN association with agricultural areas. Our study suggests that EPNs have adapted to polluted habitats that might support arthropod hosts. By contrast, the relationship between abundance of Acrobeloides-group and heavy-metal levels, revealed these taxa as especially well suited bio

WormBase: Annotating many nematode genomes.

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Howe, Kevin; Davis, Paul; Paulini, Michael; Tuli, Mary Ann; Williams, Gary; Yook, Karen; Durbin, Richard; Kersey, Paul; Sternberg, Paul W

2012-01-01

WormBase (www.wormbase.org) has been serving the scientific community for over 11 years as the central repository for genomic and genetic information for the soil nematode Caenorhabditis elegans. The resource has evolved from its beginnings as a database housing the genomic sequence and genetic and physical maps of a single species, and now represents the breadth and diversity of nematode research, currently serving genome sequence and annotation for around 20 nematodes. In this article, we focus on WormBase's role of genome sequence annotation, describing how we annotate and integrate data from a growing collection of nematode species and strains. We also review our approaches to sequence curation, and discuss the impact on annotation quality of large functional genomics projects such as modENCODE.

Chitosan-based nanoparticles of avermectin to control pine wood nematodes.

Science.gov (United States)

Liang, Wenlong; Yu, Aixin; Wang, Guodong; Zheng, Feng; Jia, Jinliang; Xu, Hanhong

2018-06-01

Pine wood nematode disease is a most devastating disease of pine trees. Avermectin (AVM) is a widely used bio-nematocide which can effectively to kill the pine wood nematode (PWN). However, its poor solubility in water and rapid photolysis are responsible for its poor bioavailability, which causes environmental pollution because of excessive applied rates. Here, a simple electrostatic interaction method was used to encapsulate AVM within nanoparticles composed of poly-γ-glutamic acid (γ-PGA) and chitosan (CS). The loading capacity of the resulting AVM-CS/γ-PGA nanoparticles was as much as 30.5%. The encapsulation of AVM within these nanoparticles reduced its losses by more than 20.0% through photolysis. An in vitro test showed that the rate of release of AVM from the nanoparticles was dependent on the ambient pH, with rapid release occurring in an alkaline environment. The mortality rate of nematodes which were treated with 1ppm of AVM content of AVM-CS/γ-PGA was 98.6% after 24h, while one of free AVM was only 69.9%. In addition, FITC-labeled CS/γ-PGA nanoparticles (FITC-CS/γ-PGA) showed that the nanoparticles could enrich in intestines and head of nematodes. All of these results showed that those nanoparticles of AVM are a potential multifunctional formulation to control the pest and reduce environment pollution. Copyright © 2018 Elsevier B.V. All rights reserved.

Transgenic potatoes for potato cyst nematode control can replace pesticide use without impact on soil quality.

Science.gov (United States)

Green, Jayne; Wang, Dong; Lilley, Catherine J; Urwin, Peter E; Atkinson, Howard J

2012-01-01

Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode) for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community.

Transgenic potatoes for potato cyst nematode control can replace pesticide use without impact on soil quality.

Directory of Open Access Journals (Sweden)

Jayne Green

Full Text Available Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community.

Standardization of sequential separation of naturally occurring radionuclides in drinking water

International Nuclear Information System (INIS)

Nair, Madhu G.; Rao, D.D.; Sathyapriya, R.S.; Sarkar, P.K.

2012-01-01

Human are constantly exposed to radiation originating from natural or manmade sources. The main contribution for internal dose is due to radionuclides from uranium and thorium series in drinking water. The distribution of these elements varies depending on the geological and physiological characteristics of the aquifer. With increased concern for radiological safety of public, it is necessary to evaluate the naturally occurring radionuclides in the drinking water

Daily intakes of naturally occurring radioisotopes in typical Korean foods

International Nuclear Information System (INIS)

Choi, Min-Seok; Lin Xiujing; Lee, Sun Ah; Kim, Wan; Kang, Hee-Dong; Doh, Sih-Hong; Kim, Do-Sung; Lee, Dong-Myung

2008-01-01

The concentrations of naturally occurring radioisotopes ( 232 Th, 228 Th, 230 Th, 228 Ra, 226 Ra, and 40 K) in typical Korean foods were evaluated. The daily intakes of these radioisotopes were calculated by comparing concentrations in typical Korean foods and the daily consumption rates of these foods. Daily intakes were as follows: 232 Th, 0.00-0.23; 228 Th, 0.00-2.04; 230 Th, 0.00-0.26; 228 Ra, 0.02-2.73; 226 Ra, 0.01-4.37 mBq/day; and 40 K, 0.01-5.71 Bq/day. The total daily intake of the naturally occurring radioisotopes measured in this study from food was 39.46 Bq/day. The total annual internal dose resulting from ingestion of radioisotopes in food was 109.83 μSv/y, and the radioisotope with the highest daily intake was 40 K. These values were same level compiled in other countries

The dual effects of root-cap exudates on nematodes: from quiescence in plant-parasitic nematodes to frenzy in entomopathogenic nematodes.

Science.gov (United States)

Hiltpold, Ivan; Jaffuel, Geoffrey; Turlings, Ted C J

2015-02-01

To defend themselves against herbivores and pathogens, plants produce numerous secondary metabolites, either constitutively or de novo in response to attacks. An intriguing constitutive example is the exudate produced by certain root-cap cells that can induce a state of reversible quiescence in plant-parasitic nematodes, thereby providing protection against these antagonists. The effect of such root exudates on beneficial entomopathogenic nematodes (EPNs) remains unclear, but could potentially impair their use in pest management programmes. We therefore tested how the exudates secreted by green pea (Pisum sativum) root caps affect four commercial EPN species. The exudates induced reversible quiescence in all EPN species tested. Quiescence levels varied with the green pea cultivars tested. Notably, after storage in root exudate, EPN performance traits were maintained over time, whereas performances of EPNs stored in water rapidly declined. In sharp contrast to high concentrations, lower concentrations of the exudate resulted in a significant increase in EPN activity and infectiousness, but still reduced the activity of two plant-parasitic nematode species. Our study suggests a finely tuned dual bioactivity of the exudate from green pea root caps. Appropriately formulated, it can favour long-term storage of EPNs and boost their infectiousness, while it may also be used to protect plants from plant-parasitic nematodes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Root-knot nematode management in double-cropped plasticulture vegetables.

Science.gov (United States)

Desaeger, J A; Csinos, A S

2006-03-01

Combination treatments of chisel-injected fumigants (methyl bromide, 1,3-D, metam sodium, and chloropicrin) on a first crop, followed by drip-applied fumigants (metam sodium and 1,3-D +/- chloropicrin) on a second crop, with and without oxamyl drip applications were evaluated for control of Meloidogyne incognita in three different tests (2002 to 2004) in Tifton, GA. First crops were eggplant or tomato, and second crops were cantaloupe, squash, or jalapeno pepper. Double-cropped vegetables suffered much greater root-knot nematode (RKN) pressure than first crops, and almost-total yield loss occurred when second crops received no nematicide treatment. On a first crop of eggplant, all fumigants provided good nematode control and average yield increases of 10% to 15 %. On second crops, higher application rates and fumigant combinations (metam sodium and 1,3-D +/- chloropicrin) improved RKN control and increased yields on average by 20% to 35 % compared to the nonfumigated control. Oxamyl increased yields of the first crop in 2003 on average by 10% to 15% but had no effect in 2004 when RKN failed to establish itself. On double-cropped squash in 2003, oxamyl following fumigation provided significant additional reduction in nematode infection and increased squash yields on average by 30% to 75%.

Natural selection on individual variation in tolerance of gastrointestinal nematode infection.

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Adam D Hayward

2014-07-01

Full Text Available Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host-parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance, other individuals lost weight significantly more rapidly (exhibiting low tolerance. We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites.

Spatial and temporal variation of intertidal nematodes in the northern Gulf of Mexico after the Deepwater Horizon oil spill.

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Brannock, Pamela M; Sharma, Jyotsna; Bik, Holly M; Thomas, W Kelley; Halanych, Kenneth M

2017-09-01

Nematodes are an abundant and diverse interstitial component of sedimentary habitats that have been reported to serve as important bioindicators. Though the 2010 Deepwater Horizon (DWH) disaster occurred 60 km offshore in the Gulf of Mexico (GOM) at a depth of 1525 m, oil rose to the surface and washed ashore, subjecting large segments of coastline in the northern GOM to contamination. Previous metabarcoding work shows intertidal nematode communities were negatively affected by the oil spill. Here we examine the subsequent recovery of nematode community structure at five sites along the Alabama coast over a two-year period. The latter part of the study (July 2011-July 2012) also included an examination of nematode vertical distribution in intertidal sediments. Results showed nematode composition within this region was more influenced by sample locality than time and depth. The five sampling sites were characterized by distinct nematode assemblages that varied by sampling dates. Nematode diversity decreased four months after the oil spill but increased after one year, returning to previous levels at all sites except Bayfront Park (BP). There was no significant difference among nematode assemblages in reference to vertical distribution. Although the composition of nematode assemblages changed, the feeding guilds they represented were not significantly different even though some variation was noted. Data from morphological observations integrated with metabarcoding data indicated similar spatial variation in nematode distribution patterns, indicating the potential of using these faster approaches to examine overall disturbance impact trends within communities. Heterogeneity of microhabitats in the intertidal zone indicates that future sampling and fine-scale studies of nematodes are needed to examine such anthropogenic effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes in plant species richness induce functional shifts in soil nematode communities in experimental grassland.

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Nico Eisenhauer

Full Text Available Changes in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.We studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment. In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.The results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant-nematode interactions.

Multifaceted effects of host plants on entomopathogenic nematodes.

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Hazir, Selcuk; Shapiro-Ilan, David I; Hazir, Canan; Leite, Luis G; Cakmak, Ibrahim; Olson, Dawn

2016-03-01

The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs. Copyright © 2016

Targeted mutagenesis in a human-parasitic nematode

Science.gov (United States)

Gang, Spencer S.; Castelletto, Michelle L.

2017-01-01

Parasitic nematodes infect over 1 billion people worldwide and cause some of the most common neglected tropical diseases. Despite their prevalence, our understanding of the biology of parasitic nematodes has been limited by the lack of tools for genetic intervention. In particular, it has not yet been possible to generate targeted gene disruptions and mutant phenotypes in any parasitic nematode. Here, we report the development of a method for introducing CRISPR-Cas9-mediated gene disruptions in the human-parasitic threadworm Strongyloides stercoralis. We disrupted the S. stercoralis twitchin gene unc-22, resulting in nematodes with severe motility defects. Ss-unc-22 mutations were resolved by homology-directed repair when a repair template was provided. Omission of a repair template resulted in deletions at the target locus. Ss-unc-22 mutations were heritable; we passed Ss-unc-22 mutants through a host and successfully recovered mutant progeny. Using a similar approach, we also disrupted the unc-22 gene of the rat-parasitic nematode Strongyloides ratti. Our results demonstrate the applicability of CRISPR-Cas9 to parasitic nematodes, and thereby enable future studies of gene function in these medically relevant but previously genetically intractable parasites. PMID:29016680

Tomato transgenic plants expressing hairpin construct of a nematode protease gene conferred enhanced resistance to root-knot nematodes

Directory of Open Access Journals (Sweden)

Tushar Kanti Dutta

2015-04-01

Full Text Available Root-knot nematodes (Meloidogyne incognita cause substantial yield losses in vegetables worldwide, and are difficult to manage. Continuous withdrawal of environmentally-harmful nematicides from the global market warrants the need for novel nematode management strategies. Utility of host-delivered RNAi has been demonstrated in several plants (Arabidopsis, tobacco and soybean that exhibited resistance against root-knot and cyst nematodes. Herein, a M. incognita-specific protease gene, cathepsin L cysteine proteinase (Mi-cpl-1, was targeted to generate tomato transgenic lines to evaluate the genetically modified nematode resistance. In vitro knockdown of Mi-cpl-1 gene led to the reduced attraction and penetration of M. incognita in tomato, suggesting the involvement of Mi-cpl-1 in nematode parasitism. Transgenic expression of the RNAi construct of Mi-cpl-1 gene resulted in 60-80% reduction in infection and multiplication of M. incognita in tomato. Evidence for in vitro and in vivo silencing of Mi-cpl-1 was confirmed by expression analysis using quantitative PCR. Our study demonstrates that Mi-cpl-1 plays crucial role during plant-nematode interaction and plant-mediated downregulation of this gene elicits detrimental effect on M. incognita development, reinforcing the potential of RNAi technology for management of phytonematodes in crop plants.

Entomopathogenic nematodes in the European biocontrol market.

Science.gov (United States)

Ehlers, R U

2003-01-01

In Europe total revenues in the biocontrol market have reached approximately 200 million Euros. The sector with the highest turn-over is the market for beneficial invertebrates with a 55% share, followed by microbial agents with approximately 25%. Annual growth rates of up to 20% have been estimated. Besides microbial plant protection products that are currently in the process of re-registration, several microbial products have been registered or are in the process of registration, following the EU directive 91/414. Entomopathogenic nematodes (EPN) are exceptionally safe biocontrol agents. Until today, they are exempted from registration in most European countries, the reason why SMEs were able to offer economically reasonable nematode-based products. The development of technology for mass production in liquid media significantly reduced the product costs and accelerated the introduction of nematode products in tree nurseries, ornamentals, strawberries, mushrooms, citrus and turf. Progress in storage and formulation technology has resulted in high quality products which are more resistant to environmental extremes occurring during transportation to the user. The cooperation between science, industry and extension within the EU COST Action 819 has supported the development of quality control methods. Today four companies produce EPN in liquid culture, offering 8 different nematode species. Problems with soil insects are increasing. Grubs, like Melolontha melolontha and other scarabaeidae cause damage in orchards and turf. Since the introduction of the Western Corn Rootworm Diabrotica virgifera into Serbia in 1992, this pests as spread all over the Balkan Region and has reached Italy, France and Austria. These soil insect pests are potential targets for EPN. The development of insecticide resistance has opened another sector for EPN. Novel adjuvants used to improve formulation of EPN have enabled the foliar application against Western Flower Thrips and Plutella

powdery leaf extracts for control of root knot nematode in african ...

African Journals Online (AJOL)

journal

Synthetic chemicals have been used to control plant pathogenic nematodes in the farmers fields. These chemicals, though valued for their effectiveness, are costly and may constitute health hazards to farm households and the environment. Reducing these situations in the farms through use of natural plant extracts is one of ...

Bioactive natural products from novel microbial sources.

Science.gov (United States)

Challinor, Victoria L; Bode, Helge B

2015-09-01

Despite the importance of microbial natural products for human health, only a few bacterial genera have been mined for the new natural products needed to overcome the urgent threat of antibiotic resistance. This is surprising, given that genome sequencing projects have revealed that the capability to produce natural products is not a rare feature among bacteria. Even the bacteria occurring in the human microbiome produce potent antibiotics, and thus potentially are an untapped resource for novel compounds, potentially with new activities. This review highlights examples of bacteria that should be considered new sources of natural products, including anaerobes, pathogens, and symbionts of humans, insects, and nematodes. Exploitation of these producer strains, combined with advances in modern natural product research methodology, has the potential to open the way for a new golden age of microbial therapeutics. © 2015 New York Academy of Sciences.

Phloem development in nematode-induced feeding sites: The implications of auxin and cytokinin

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Birgit eAbsmanner

2013-07-01

Full Text Available Sedentary plant parasitic nematodes such as root-knot nematodes and cyst nematodes induce giant cells or syncytia, respectively, in their host plant’s roots. These highly specialized structures serve as feeding sites from which exclusively the nematodes withdraw nutrients. While giant cells are symplastically isolated and obtain assimilates by transporter-mediated processes syncytia are massively connected to the phloem by plasmodesmata. To support the feeding sites and the nematode during their development, phloem is induced around syncytia and giant cells. In the case of syncytia the unloading phloem consists of sieve elements and companion cells and in the case of root knots it consists exclusively of sieve elements. We applied immunohistochemistry to identify the cells within the developing phloem that responded to auxin and cytokinin. Both feeding sites themselves did not respond to either hormone. We were able to show that in root knots an auxin response precedes the differentiation of these auxin responsive cells into phloem elements. This process appears to be independent of B-type Arabidopsis response regulators. Using additional markers for tissue identity we provide evidence that around giant cells protophloem is formed and proliferates dramatically. In contrast, the phloem around syncytia responded to both hormones. The presence of companion cells as well as hormone-responsive sieve elements suggests that metaphloem development occurs. The implication of auxin and cytokinin in the further development of the metaphloem is discussed.

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil.

Science.gov (United States)

Ramos, Fernanda; Portella, Luiza Pires; Rodrigues, Fernando de Souza; Reginato, Caroline Zamperete; Pötter, Luciana; Cezar, Alfredo Skrebsky; Sangioni, Luís Antônio; Vogel, Fernanda Silveira Flores

2016-04-01

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70-100 calves or more of both genders with ≥ 200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7-10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7-10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups were effective

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil

Science.gov (United States)

Ramos, Fernanda; Portella, Luiza Pires; Rodrigues, Fernando de Souza; Reginato, Caroline Zamperete; Pötter, Luciana; Cezar, Alfredo Skrebsky; Sangioni, Luís Antônio; Vogel, Fernanda Silveira Flores

2016-01-01

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70–100 calves or more of both genders with ≥200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7–10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7–10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups

Opportunity to use native nematodes for pest control

Science.gov (United States)

We have surveyed wild cranberry bogs in WI and found three isolates of native nematodes. We have been testing these nematodes as potential biological control agents in for cranberry insect pests including sparganothis fruitworm and flea beetle. The nematodes seem to be effective at finding and killi...

Basic and applied research: Entomopathogenic nematodes

Science.gov (United States)

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema kill arthropods with the aid of their bacterial symbionts. These nematodes are potent microbial control agents that have been widely commercialized for control of economically important insect pests. Biocontrol efficacy relies...

The prevalence of gastrointestinal nematode infection and their ...

African Journals Online (AJOL)

GIN infection was associated with 1.4 litres per cow per day less milk and this ... Gastrointestinal nematode (GIN) infections in cattle are of considerable economic importance .... Table 2. Mean faecal egg counts of gastrointestinal nematodes and the 95% confidence ... 3.2 Gastrointestinal nematode species. The pooled ...

Multipartite Symbioses Among Fungi, Mites, Nematodes, and the Spruce Beetle, Dendroctonus rufipennis.

Science.gov (United States)

Yasmin Cardoza; John Moser; Kier Klepzizg; Raffa Kenneth

2008-01-01

The spruce beetle, Dendroctonus rufipennis, is an eruptive forest pest of signifcant economic and ecological importance. D. rufipennis has symbiotic associations with a number of microorganisms, especially the ophiostomatoid fungus Leptographium abietinum. The nature of this interaction is only partially understood. Additionally, mite and nematode associates can...

Cryopreservation of roe deer abomasal nematodes for morphological identification.

Science.gov (United States)

Beraldo, Paola; Pascotto, Ernesto

2014-02-01

Conventional methods to preserve adult nematodes for taxonomic purposes involve the use of fixative or clearing solutions (alcohol, formaldehyde, AFA and lactophenol), which cause morphological alterations and are toxic. The aim of this study is to propose an alternative method based on glycerol-cryopreservation of nematodes for their subsequent identification. Adults of trichostrongylid nematodes from the abomasum of roe deer (Capreolus capreolus Linnaeus) were glycerol-cryopreserved and compared with those fixed in formaldehyde, fresh and frozen without cryoprotectans. Morphology, transparency and elasticity of the anterior and posterior portion of male nematodes were compared, especially the caudal cuticular bursa and genital accessories. The method presented is quick and easy to use, and the quality of nematode specimens is better than that of nematodes fixed by previously used fixatives. Moreover, glycerol cryopreserved nematodes can be stored for a long time at -20 degrees C in perfect condition and they could be suitable for further analyses, such as histological or ultrastructural examinations.

Diversity of bacteria carried by pinewood nematode in USA and phylogenetic comparison with isolates from other countries.

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Diogo Neves Proença

Full Text Available Pine wilt disease (PWD is native to North America and has spread to Asia and Europe. Lately, mutualistic relationship has been suggested between the pinewood nematode (PWN, Bursaphelenchus xylophilus the causal nematode agent of PWD, and bacteria. In countries where PWN occurs, nematodes from diseased trees were reported to carry bacteria from several genera. However no data exists for the United States. The objective of this study was to evaluate the diversity of the bacterial community carried by B. xylophilus, isolated from different Pinus spp. with PWD in Nebraska, United States. The bacteria carried by PWN belonged to Gammaproteobacteria (79.9%, Betaproteobacteria (11.7%, Bacilli (5.0%, Alphaproteobacteria (1.7% and Flavobacteriia (1.7%. Strains from the genera Chryseobacterium and Pigmentiphaga were found associated with the nematode for the first time. These results were compared to results from similar studies conducted from other countries of three continents in order to assess the diversity of bacteria with associated with PWN. The isolates from the United States, Portugal and China belonged to 25 different genera and only strains from the genus Pseudomonas were found in nematodes from all countries. The strains from China were closely related to P. fluorescens and the strains isolated from Portugal and USA were phylogenetically related to P. mohnii and P. lutea. Nematodes from the different countries are associated with bacteria of different species, not supporting a relationship between PWN with a particular bacterial species. Moreover, the diversity of the bacteria carried by the pinewood nematode seems to be related to the geographic area and the Pinus species. The roles these bacteria play within the pine trees or when associated with the nematodes, might be independent of the presence of the nematode in the tree and only related on the bacteria's relationship with the tree.

From phenotypic to molecular polymorphisms involved in naturally occurring variation for plant development

NARCIS (Netherlands)

Alonso-Blanco, C.; Mendez-Vigo, B.; Koornneef, M.

2005-01-01

An enormous amount of naturally occurring genetic variation affecting development is found within wild and domesticated plant species. This diversity is presumably involved in plant adaptation to different natural environments or in human preferences. In addition, such intraspecific variation

Benthic communities in chemical munitions dumping site areas within the Baltic deeps with special focus on nematodes

Science.gov (United States)

Kotwicki, Lech; Grzelak, Katarzyna; Bełdowski, Jacek

2016-06-01

Assessment of biological effects of chemical warfare agents (CWAs) dumped in the Baltic Sea has been one of the tasks of the Chemical Munitions Search & Assessment (CHEMSEA) project. Three sites have been selected for investigation: Bornholm Deep, Gotland Deep and Gdansk Deep. Fauna collected from these locations were compared with the reference area located between the studied regions at similar depths below 70 m. In total, four scientific cruises occurred in different seasons between 2011 and 2013. The total lack of any representatives of macrozoobenthos in all of the investigated dumping sites was noted. As a practical matter, the Baltic deeps were inhabited by nematodes as the only meiofauna representatives. Therefore, nematodes were used as a key group to explore the faunal communities inhabiting chemical dumping sites in the Baltic deeps. In total, 42 nematode genera belonging to 18 families were identified, and the dominant genus was Sabatieria (Comesomatidae), which constituted 37.6% of the overall nematode community. There were significant differences in nematode community structure (abundance and taxa composition) between the dumping areas and the reference site (Kruskal-Wallis H=30.96, pnematode assemblages could mirror the environmental conditions.

Biocontrol: Fungal Parasites of Female Cyst Nematodes

OpenAIRE

Kerry, Brian

1980-01-01

Three species of fungi, Catenaria auxiliarls (Kühn) Tribe, Nematophthora gynophila Kerry and Crump, and a Lagenidiaceous fungus have been found attacking female cyst nematodes. All are zoosporic fungi which parasitize females on the root surface, cause the breakdown of the nematode cuticle, and prevent cyst formation. Their identification and some aspects of their biology are reviewed. N. gynophila is widespread in Britain and reduces populations of the cereal cyst nematode, Heterodera avenae...

Identification, Validation and Utilization of Novel Nematode-Responsive Root-Specific Promoters in Arabidopsis for Inducing Host-Delivered RNAi Mediated Root-Knot Nematode Resistance

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Atul Kakrana

2017-12-01

Full Text Available The root-knot nematode (RKN, Meloidogyne incognita, is an obligate, sedentary endoparasite that infects a large number of crops and severely affects productivity. The commonly used nematode control strategies have their own limitations. Of late, RNA interference (RNAi has become a popular approach for the development of nematode resistance in plants. Transgenic crops capable of expressing dsRNAs, specifically in roots for disrupting the parasitic process, offer an effective and efficient means of producing resistant crops. We identified nematode-responsive and root-specific (NRRS promoters by using microarray data from the public domain and known conserved cis-elements. A set of 51 NRRS genes was identified which was narrowed down further on the basis of presence of cis-elements combined with minimal expression in the absence of nematode infection. The comparative analysis of promoters from the enriched NRRS set, along with earlier reported nematode-responsive genes, led to the identification of specific cis-elements. The promoters of two candidate genes were used to generate transgenic plants harboring promoter GUS constructs and tested in planta against nematodes. Both promoters showed preferential expression upon nematode infection, exclusively in the root in one and galls in the other. One of these NRRS promoters was used to drive the expression of splicing factor, a nematode-specific gene, for generating host-delivered RNAi-mediated nematode-resistant plants. Transgenic lines expressing dsRNA of splicing factor under the NRRS promoter exhibited upto a 32% reduction in number of galls compared to control plants.

Large-scale distribution patterns of mangrove nematodes: A global meta-analysis.

Science.gov (United States)

Brustolin, Marco C; Nagelkerken, Ivan; Fonseca, Gustavo

2018-05-01

Mangroves harbor diverse invertebrate communities, suggesting that macroecological distribution patterns of habitat-forming foundation species drive the associated faunal distribution. Whether these are driven by mangrove biogeography is still ambiguous. For small-bodied taxa, local factors and landscape metrics might be as important as macroecology. We performed a meta-analysis to address the following questions: (1) can richness of mangrove trees explain macroecological patterns of nematode richness? and (2) do local landscape attributes have equal or higher importance than biogeography in structuring nematode richness? Mangrove areas of Caribbean-Southwest Atlantic, Western Indian, Central Indo-Pacific, and Southwest Pacific biogeographic regions. We used random-effects meta-analyses based on natural logarithm of the response ratio (lnRR) to assess the importance of macroecology (i.e., biogeographic regions, latitude, longitude), local factors (i.e., aboveground mangrove biomass and tree richness), and landscape metrics (forest area and shape) in structuring nematode richness from 34 mangroves sites around the world. Latitude, mangrove forest area, and forest shape index explained 19% of the heterogeneity across studies. Richness was higher at low latitudes, closer to the equator. At local scales, richness increased slightly with landscape complexity and decreased with forest shape index. Our results contrast with biogeographic diversity patterns of mangrove-associated taxa. Global-scale nematode diversity may have evolved independently of mangrove tree richness, and diversity of small-bodied metazoans is probably more closely driven by latitude and associated climates, rather than local, landscape, or global biogeographic patterns.

Identification of a bacteria-like ferrochelatase in Strongyloides venezuelensis, an animal parasitic nematode.

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Eiji Nagayasu

Full Text Available Heme is an essential molecule for vast majority of organisms serving as a prosthetic group for various hemoproteins. Although most organisms synthesize heme from 5-aminolevulinic acid through a conserved heme biosynthetic pathway composed of seven consecutive enzymatic reactions, nematodes are known to be natural heme auxotrophs. The completely sequenced Caenorhabditis elegans genome, for example, lacks all seven genes for heme biosynthesis. However, genome/transcriptome sequencing of Strongyloides venezuelensis, an important model nematode species for studying human strongyloidiasis, indicated the presence of a gene for ferrochelatase (FeCH, which catalyzes the terminal step of heme biosynthesis, whereas the other six heme biosynthesis genes are apparently missing. Phylogenetic analyses indicated that nematode FeCH genes, including that of S. venezuelensis (SvFeCH have a fundamentally different evolutionally origin from the FeCH genes of non-nematode metazoa. Although all non-nematode metazoan FeCH genes appear to be inherited vertically from an ancestral opisthokont, nematode FeCH may have been acquired from an alpha-proteobacterium, horizontally. The identified SvFeCH sequence was found to function as FeCH as expected based on both in vitro chelatase assays using recombinant SvFeCH and in vivo complementation experiments using an FeCH-deficient strain of Escherichia coli. Messenger RNA expression levels during the S. venezuelensis lifecycle were examined by real-time RT-PCR. SvFeCH mRNA was expressed at all the stages examined with a marked reduction at the infective third-stage larvae. Our study demonstrates the presence of a bacteria-like FeCH gene in the S. venezuelensis genome. It appeared that S. venezuelensis and some other animal parasitic nematodes reacquired the once-lost FeCH gene. Although the underlying evolutionary pressures that necessitated this reacquisition remain to be investigated, it is interesting that the presence of Fe

Prevalence of Gastro-Intestinal Nematodes in Goats in Hyderabad and Adjoining Areas

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Nasreen Akhter*, A. G. Arijo, M. S. Phulan, Zafar Iqbal1 and K. B. Mirbahar

2011-10-01

Full Text Available The study was conducted to determine the prevalence of gastrointestinal nematodes of goats (n=1065 in and around Hyderabad using qualitative and quantitative coprological examinations. Results revealed that 43.10% (459 goats were infected with different species of nematodes including Haemonchus contortus (14.65%, Trichuris ovis (8.17%, Trichostrongylus axei (7.61%, Trichostrongylus colubriformis (6.76%, Oesphagostomum columbianum (5.35%, Ostertagia circumcincta (5.35%, Chabertia ovina (4.79% and Strongyloides papillosus (4.51%. Infections with mixed species of nematodes were recorded in 6.54% (n=30/459; T. ovis + H. contortus, 5.23% (n=24/459; C. ovina + H. contortus, 5.88% (n=27/459; S. papillosus + C. ovina, and 12.42% (n=57/459; O. circumcincta + T. ovis goats. Of the total infected (n=459; 51.4, 38.3 and 10.2% goats had light, moderate and heavy infections, respectively. The prevalence, nature and intensity of the helminthiasis in goats warrant an immediate attention to devise strategies for its control to reduce the production losses.

Natural transformation of Campylobacter jejuni occurs beyond limits of growth

DEFF Research Database (Denmark)

Vegge, Christina Skovgaard; Brøndsted, Lone; Ligowska, Małgorzata

2012-01-01

of transformation is correlated to the growth conditions, but more importantly that transformation occurs at growth-restrictive conditions as well as in the late stationary phase; hence revealing that growth per se is not required for C. jejuni to be competent. Yet, natural transformation of C. jejuni is an energy......Campylobacter jejuni is a human bacterial pathogen. While poultry is considered to be a major source of food borne campylobacteriosis, C. jejuni is frequently found in the external environment, and water is another well-known source of human infections. Natural transformation is considered...... to be one of the main mechanisms for mediating transfer of genetic material and evolution of the organism. Given the diverse habitats of C. jejuni we set out to examine how environmental conditions and physiological processes affect natural transformation of C. jejuni. We show that the efficiency...

Naturally Occurring Radionuclides in Pottery, Ceramic and Glasswares Produced in Bangladesh

International Nuclear Information System (INIS)

Chowdhury, M.I.; Reaz, Rafia; Kamal, M.; Alam, M.N.; Mustafa, M.N.

2005-01-01

The concentrations of naturally occurring radionuclides were measured using gamma spectrometry in the finished products of pottery, glass, ceramic and tiles. Ceramic and pottery utensils, tiles, basin and glassware contained naturally occurring radionuclides. Pottery is produced from local clay materials, but ceramic, tiles, basin and glassware's are made from both local and imported raw materials. Radium and thorium radionuclides are concentrated during the making of pottery from the clay materials due to calcination. Radionuclides concentrated more in the highly calcined pottery products than the low calcined products. Glassware products contained very low quantities of radionuclides comparing with the ceramic and pottery products. Study on radioactivity in the pottery, ceramic and glassware products is important in the assessment of possible radiological hazards to human health. The knowledge is essential for the development of standards and guidelines for the use and management of these materials. (author)

Succession and dynamics of Pristionchus nematodes and their microbiome during decomposition of Oryctes borbonicus on La Réunion Island.

Science.gov (United States)

Meyer, Jan M; Baskaran, Praveen; Quast, Christian; Susoy, Vladislav; Rödelsperger, Christian; Glöckner, Frank O; Sommer, Ralf J

2017-04-01

Insects and nematodes represent the most species-rich animal taxa and they occur together in a variety of associations. Necromenic nematodes of the genus Pristionchus are found on scarab beetles with more than 30 species known from worldwide samplings. However, little is known about the dynamics and succession of nematodes and bacteria during the decomposition of beetle carcasses. Here, we study nematode and bacterial succession of the decomposing rhinoceros beetle Oryctes borbonicus on La Réunion Island. We show that Pristionchus pacificus exits the arrested dauer stage seven days after the beetles´ deaths. Surprisingly, new dauers are seen after 11 days, suggesting that some worms return to the dauer stage after one reproductive cycle. We used high-throughput sequencing of the 16S rRNA genes of decaying beetles, beetle guts and nematodes to study bacterial communities in comparison to soil. We find that soil environments have the most diverse bacterial communities. The bacterial community of living and decaying beetles are more stable but one single bacterial family dominates the microbiome of decaying beetles. In contrast, the microbiome of nematodes is relatively similar even across different families. This study represents the first characterization of the dynamics of nematode-bacterial interactions during the decomposition of insects. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Genome Evolution of Plant-Parasitic Nematodes.

Science.gov (United States)

Kikuchi, Taisei; Eves-van den Akker, Sebastian; Jones, John T

2017-08-04

Plant parasitism has evolved independently on at least four separate occasions in the phylum Nematoda. The application of next-generation sequencing (NGS) to plant-parasitic nematodes has allowed a wide range of genome- or transcriptome-level comparisons, and these have identified genome adaptations that enable parasitism of plants. Current genome data suggest that horizontal gene transfer, gene family expansions, evolution of new genes that mediate interactions with the host, and parasitism-specific gene regulation are important adaptations that allow nematodes to parasitize plants. Sequencing of a larger number of nematode genomes, including plant parasites that show different modes of parasitism or that have evolved in currently unsampled clades, and using free-living taxa as comparators would allow more detailed analysis and a better understanding of the organization of key genes within the genomes. This would facilitate a more complete understanding of the way in which parasitism has shaped the genomes of plant-parasitic nematodes.

Extended phenotype: nematodes turn ants into bird-dispersed fruits

DEFF Research Database (Denmark)

Hughes, D P; Kronauer, D J C; Boomsma, J J

2008-01-01

A recent study has discovered a novel extended phenotype of a nematode which alters its ant host to resemble ripe fruit. The infected ants are in turn eaten by frugivorous birds that disperse the nematode's eggs.......A recent study has discovered a novel extended phenotype of a nematode which alters its ant host to resemble ripe fruit. The infected ants are in turn eaten by frugivorous birds that disperse the nematode's eggs....

Biocontrol: The Potential of Entomophilic Nematodes in Insect Management

OpenAIRE

Webster, John M.

1980-01-01

A review of the development of entomophilic nematology and a commentary on the potential of entomophilic nematodes in controlling insect pests. The paper considers some of the major contributions to our knowledge of entomophilic nematology; factors involved in insect pest management and how they are applicable to the use of nematodes; nematodes which are most promising as biological control agents; and problems to be solved to facilitate the use of entomophilic nematodes in insect management.

The FMRFamide-like peptide family in nematodes

Directory of Open Access Journals (Sweden)

Katleen ePeymen

2014-06-01

Full Text Available In the three decades since the FMRFamide peptide was isolated from the mollusk Macrocallista nimbosa, structurally similar peptides sharing a C-terminal RFamide motif have been identified across the animal kingdom. FMRFamide-like peptides (FLPs represent the largest known family of neuropeptides in invertebrates. In the phylum Nematoda, at least 32 flp genes are classified, making the FLP system of nematodes unusually complex. The diversity of the nematode FLP complement is most extensively mapped in Caenorhabditis elegans, where over 70 FLPs have been predicted. FLPs have shown to be expressed in the majority of the 302 C. elegans neurons including interneurons, sensory and motor neurons. The vast expression of FLPs is reflected in the broad functional repertoire of nematode FLP signaling, including neuroendocrine and neuromodulatory effects on locomotory activity, reproduction, feeding, and behavior. In contrast to the many identified nematode FLPs, only few peptides have been assigned a receptor and there is the need to clarify the pathway components and working mechanisms of the FLP signaling network. Here, we review the diversity, distribution, and functions of FLPs in nematodes.

Biology and predatory attributes of a diplogasterid nematode, Fictor composticola Khan et al., 2008

Directory of Open Access Journals (Sweden)

Bajaj H. K.

2015-02-01

Full Text Available Biology of Fictor composticola has been studied on Aphelenchus avenae in vitro. It reproduces by amphimixis, embryonic development is completed in 24 - 27 h and life cycle in 3 - 4 days. Fusion of sperm and egg pronuclei occurs in the uteri. Pulsation of median oesophageal bulb and pressing of lips against egg shell is seen just prior to hatching but teeth seem to play no role in this process. No moulting occurs inside the egg shell and the first stage juvenile hatches out. Female and male undergo mating upon addition of water in the culture plates and continue to swim in copula for a considerable time. A female lays 1.6 - 4.0 eggs in 24 h while feeding upon A. radicicolus. Predation and reproduction is affected by the temperature and 25 - 35 °C is the optimum range for these phenomena. Process of feeding as recorded with a CCTV attached to a compound microscope is described. F. composticola engulfs small preys; sucks the intestinal contents while holding them or cuts the body wall of large-sized preys and then feeds on prolapsed organs. Two sexes differ in their efficiencies of predation, a female on an average kills 53 A. avenae as compared to 11 by a male in 24 h. F. composticola feeds and reproduces on mycophagous nematodes and juveniles of root- knot, cyst and citrus nematodes but does not prey upon adult nematodes having coarsely annulated cuticle. Cannibalism in this species is also observed. F. composticola and Seinura paratenuicaudata prey upon each other. Biocontrol potential of F. composticola for managing nematode problems in button mushroom and agricultural crops has also been discussed.

Linear distribution of nematodes in the gastrointestinal tract of tracer lambs.

Science.gov (United States)

Makovcová, Katerina; Langrová, Iva; Vadlejch, Jaroslav; Jankovská, Ivana; Lytvynets, Andriy; Borkovcová, Marie

2008-12-01

Forty-eight tracer lambs were killed in 2004-2007. The abomasum, duodenum, small intestine (jejunum and ileum), colon and caecum were collected and processed for parasites enumeration and identification-mucosal scrapings of both abomasums and intestines were digested. Out of 48 gastrointestinal tracts examined, all were found to be positive for nematode infection. Seventeen species of gastrointestinal nematodes were recovered: Bunostomum trigonocephalum, Cooperia curticei, Haemonchus contortus, Chabertia ovina, Nematodirus battus, Nematodirus filicollis, Oesophagostomum venulosum, Teladorsagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus vitrinus, Strongyloides papillosus, Trichuris ovis, Trichuris globulosa, Trichuris skrjabini and Skrjabinema ovis. All species were searched for in the entire gastrointestinal tract. Six species of nematodes were recovered from abnormal sites, naturally in small numbers of lambs as well as in small amounts: Nematodirus battus in the abomasums (6.67% of lambs), N. filicollis in the caecum and in the colon (%4 and 8%, respectively), T. axei in the colon (9.52%), T. colubriformis in the colon (13.89%), T. vitrinus in the caecum (16.67%), in the colon (20.00%) and in the abomasum (3.33%). T. ovis was found in one case in the small intestine.

Mind the gaps in research on the control of gastrointestinal nematodes of farmed ruminants and pigs

DEFF Research Database (Denmark)

Charlier, J; Thamsborg, S M; Bartley, D J

2018-01-01

, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow-up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face......Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs......-use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio-psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create...

Biological Effect of Leaf Aqueous Extract of Caesalpinia pyramidalis in Goats Naturally Infected with Gastrointestinal Nematodes

Science.gov (United States)

Borges-dos-Santos, Roberto Robson; López, Jorge A.; Santos, Luciano C.; Zacharias, Farouk; David, Jorge Maurício; David, Juceni Pereira; Lima, Fernanda Washington de Mendonça

2012-01-01

Forty-eight goats naturally infected with gastrointestinal nematodes were randomly divided into four groups (n = 12): negative control (G1) (untreated), positive control (G2) (treated with doramectin, 1 mL/50 Kg b.w.), and G3 and G4 treated with 2.5 and 5 mg/Kg b.w. of a leaf aqueous extract of Caesalpinia pyramidalis (CP). Fecal and blood samples were regularly collected for the evaluation of fecal egg count (FEC), hematological and immunological parameters to assess the anthelmintic activity. In treated animals with CP, there was noted a significant reduction of 54.6 and 71.2% in the mean FEC (P < 0.05). An increase in IgA levels was observed in G3 and G4 (P < 0.05), during the experimental period, suggesting that it was stimulated by the extract administration. In conclusion, the results showed that CP provoked a protective response in infected animals treated with them. This response could be partly explained by the CP chemical composition. PMID:22548117

Predicting Emotions in Facial Expressions from the Annotations in Naturally Occurring First Encounters

DEFF Research Database (Denmark)

Navarretta, Costanza

2014-01-01

This paper deals with the automatic identification of emotions from the manual annotations of the shape and functions of facial expressions in a Danish corpus of video recorded naturally occurring first encounters. More specifically, a support vector classified is trained on the corpus annotations...... to identify emotions in facial expressions. In the classification experiments, we test to what extent emotions expressed in naturally-occurring conversations can be identified automatically by a classifier trained on the manual annotations of the shape of facial expressions and co-occurring speech tokens. We...... also investigate the relation between emotions and the communicative functions of facial expressions. Both emotion labels and their values in a three dimensional space are identified. The three dimensions are Pleasure, Arousal and Dominance. The results of our experiments indicate that the classifiers...

Management and control of gastrointestinal nematodes in communal goat farms in Zimbabwe.

Science.gov (United States)

Zvinorova, P I; Halimani, T E; Muchadeyi, F C; Katsande, S; Gusha, J; Dzama, K

2017-02-01

Goats are an important source of livelihood especially in smallholder communities. Infections with gastrointestinal nematodes (GIN) remain the most prevalent parasitic diseases affecting small ruminants. The study was conducted to assess management, the level of knowledge and control of gastrointestinal nematodes. Surveys were conducted in Chipinge, Shurugwi, Binga, Tsholotsho and Matobo districts, representing the five natural/agro-ecological regions (NR) in Zimbabwe. Data was collected in 135 households using a pre-tested semi-structured questionnaire. Results indicated that goats were ranked the most important livestock species, with high flock sizes in NR IV and V. Partitioning of roles was such that the adult males were involved in decision-making while females and children were involved in day-to-day management of animals. Farmers showed low levels of input use, with natural pasture (98.4%) being the main feed source and indigenous breeds (73.2%) being kept. Farmers ranked food and financial benefits as the main reasons for keeping goats. Gastrointestinal nematodes ranked the highest as the most common disease, with majority of farmers (57%) not controlling or treating animals and 63% of farmers not having knowledge on the spread of GIN. Access to veterinary services, anthelmintic class used and breeds used by the farmers had the highest effects on parasitic infections in households. Farmer education is required for capacitation of farmer in terms of disease prevention and control so as to improve goat production.

Developmental systems of plasticity and trans-generational epigenetic inheritance in nematodes.

Science.gov (United States)

Serobyan, Vahan; Sommer, Ralf J

2017-08-01

Several decades of research provided detailed insight into how genes control development and evolution, whereas recent studies have expanded this purely genetic perspective by presenting strong evidence for environmental and epigenetic influences. We summarize examples of phenotypic plasticity and trans-generational epigenetic inheritance in the nematode model organisms Pristionchus pacificus and Caenorhabditis elegans, which indicate that the response of developmental systems to environmental influences is hardwired into the organismś genome. We argue that genetic programs regulating these organismal-environmental interactions are themselves subject to natural selection. Indeed, macro-evolutionary studies of nematode feeding structures indicate evolutionary trajectories in which plasticity followed by genetic assimilation results in extreme diversity highlighting the role of plasticity as major facilitator of phenotypic diversification. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of supplementary feeding on the resilience and resistance of browsing Criollo kids against natural gastrointestinal nematode infections during the rainy season in tropical Mexico.

Science.gov (United States)

Torres-Acosta, J F J; Jacobs, D E; Aguilar-Caballero, A; Sandoval-Castro, C; May-Martinez, M; Cob-Galera, L A

2004-10-05

The objective was to determine the effect of supplementary feeding on the resilience and resistance of Criollo kids against natural gastrointestinal nematode (GIN) infections, when browsing native vegetation during the wet season in tropical Mexico. Thirty-four 2-month old Criollo kids, raised nematode free, were included at weaning in a 22-week trial. The kids were placed into four groups. Two groups of 8 kids were offered 100g/day soybean and sorghum meal (26%:74%, respectively fresh basis) (treated/supplemented (T-S) and infected/supplemented (I-S)). Two groups remained with no supplement for the duration of the trial (infected/non-supplemented (I-NS) (n = 10) and treated/non-supplemented (T-NS) (n = 8)). Kids in groups T-S and T-NS were drenched with 0.2mg of moxidectin/kg body weight orally (Cydectin, Fort Dodge) every 28 days. Groups I-S and I-NS were naturally infected with GIN. The animals browsed native vegetation (for an average of 7h/day) together with a herd of 120 naturally infected adult goats. Cumulative live weight gain (CLWG), packed cell volume (PCV), haemoglobin (Hb), total plasma protein and plasma albumin were recorded every 14 days as measurements of resilience. Resistance parameters (faecal egg counts (FEC) and peripheral eosinophil counts (PEC)) were also measured. Bulk faecal cultures were made for each group every 28 days. Every month a new pair of tracer kids assessed the infectivity of the vegetation browsed by the animals. The T-S group had the highest CLWG, PCV and Hb compared to the other three groups (P 0.05), while the I-NS group had the poorest CLWG, PCV and Hb (P Criollo kids against natural GIN infections and was economically feasible. Improved resistance was also suggested by the PEC but was not confirmed in the FEC.

Plant-parasitic nematodes: towards understanding molecular players in stress responses.

Science.gov (United States)

Gillet, François-Xavier; Bournaud, Caroline; Antonino de Souza Júnior, Jose Dijair; Grossi-de-Sa, Maria Fatima

2017-03-01

Plant-parasitic nematode interactions occur within a vast molecular plant immunity network. Following initial contact with the host plant roots, plant-parasitic nematodes (PPNs) activate basal immune responses. Defence priming involves the release in the apoplast of toxic molecules derived from reactive species or secondary metabolism. In turn, PPNs must overcome the poisonous and stressful environment at the plant-nematode interface. The ability of PPNs to escape this first line of plant immunity is crucial and will determine its virulence. Nematodes trigger crucial regulatory cytoprotective mechanisms, including antioxidant and detoxification pathways. Knowledge of the upstream regulatory components that contribute to both of these pathways in PPNs remains elusive. In this review, we discuss how PPNs probably orchestrate cytoprotection to resist plant immune responses, postulating that it may be derived from ancient molecular mechanisms. The review focuses on two transcription factors, DAF-16 and SKN-1 , which are conserved in the animal kingdom and are central regulators of cell homeostasis and immune function. Both regulate the unfolding protein response and the antioxidant and detoxification pathways. DAF-16 and SKN-1 target a broad spectrum of Caenorhabditis elegans genes coding for numerous protein families present in the secretome of PPNs. Moreover, some regulatory elements of DAF-16 and SKN-1 from C. elegans have already been identified as important genes for PPN infection. DAF-16 and SKN-1 genes may play a pivotal role in PPNs during parasitism. In the context of their hub status and mode of regulation, we suggest alternative strategies for control of PPNs through RNAi approaches. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company.

Mercury in parasitic nematodes and trematodes and their double-crested cormorant hosts: Bioaccumulation in the face of sequestration by nematodes

International Nuclear Information System (INIS)

Robinson, Stacey A.; Forbes, Mark R.; Hebert, Craig E.

2010-01-01

Endoparasites can alter their host's heavy metal concentrations by sequestering metals in their own tissues. Contracaecum spp. (a nematode), but not Drepanocephalus spathans (a trematode), were bioaccumulating mercury to concentrations 1.5 times above cormorant hosts. Nematodes did not have significantly greater stable nitrogen isotope values (δ 15 N) than their hosts, which is contradictory to prey-predator trophic enrichment studies, but is in agreement with other endoparasite-host relationships. However, Contracaecum spp. δ 13 C values were significantly greater than their hosts, which suggest that nematodes were consuming host tissues. Nematodes were accumulating and thus sequestering some of their cormorant hosts' body burden of methyl mercury; however, they were not dramatically reducing their hosts' accumulation of methyl mercury.

Host immune status affects maturation time in two nematode species--but not as predicted by a simple life-history model.

Science.gov (United States)

Guinnee, M A; Gemmill, A W; Chan, B H K; Viney, M E; Read, A F

2003-11-01

In theory, the age at which maturation occurs in parasitic nematodes is inversely related to pre-maturational mortality rate, and cross-species data on mammalian nematodes are consistent with this prediction. Immunity is a major source of parasite mortality and parasites stand to gain sizeable fitness benefits through short-term adjustments of maturation time in response to variation in immune-mediated mortality. The effects of thymus-dependent immune responses on maturation in the nematode parasites Strongyloides ratti and Nippostrongylus brasiliensis were investigated using congenitally thymus-deficient (nude) rats. As compared with worms in normal rats, reproductive maturity of parasites (presence of eggs in utero) in nude rats occurred later in S. ratti but earlier in N. brasiliensis. Immune-mediated differences in maturation time were not associated with differences in worm length. Thymus-dependent immunity had no effect on prematurational mortality. Results are discussed in relation to theoretical expectations and possible explanations for the observed patterns in parasite maturation.

NemaPath: online exploration of KEGG-based metabolic pathways for nematodes

Directory of Open Access Journals (Sweden)

Wang Zhengyuan

2008-11-01

Full Text Available Abstract Background Nematode.net http://www.nematode.net is a web-accessible resource for investigating gene sequences from parasitic and free-living nematode genomes. Beyond the well-characterized model nematode C. elegans, over 500,000 expressed sequence tags (ESTs and nearly 600,000 genome survey sequences (GSSs have been generated from 36 nematode species as part of the Parasitic Nematode Genomics Program undertaken by the Genome Center at Washington University School of Medicine. However, these sequencing data are not present in most publicly available protein databases, which only include sequences in Swiss-Prot. Swiss-Prot, in turn, relies on GenBank/Embl/DDJP for predicted proteins from complete genomes or full-length proteins. Description Here we present the NemaPath pathway server, a web-based pathway-level visualization tool for navigating putative metabolic pathways for over 30 nematode species, including 27 parasites. The NemaPath approach consists of two parts: 1 a backend tool to align and evaluate nematode genomic sequences (curated EST contigs against the annotated Kyoto Encyclopedia of Genes and Genomes (KEGG protein database; 2 a web viewing application that displays annotated KEGG pathway maps based on desired confidence levels of primary sequence similarity as defined by a user. NemaPath also provides cross-referenced access to nematode genome information provided by other tools available on Nematode.net, including: detailed NemaGene EST cluster information; putative translations; GBrowse EST cluster views; links from nematode data to external databases for corresponding synonymous C. elegans counterparts, subject matches in KEGG's gene database, and also KEGG Ontology (KO identification. Conclusion The NemaPath server hosts metabolic pathway mappings for 30 nematode species and is available on the World Wide Web at http://nematode.net/cgi-bin/keggview.cgi. The nematode source sequences used for the metabolic pathway

Determination of naturally occurring radionuclides in soil samples of Ayranci, Turkey

Science.gov (United States)

Agar, Osman; Eke, Canel; Boztosun, Ismail; Emin Korkmaz, M.

2015-04-01

The specific activity, radiation hazard index and the annual effective dose of the naturally occurring radioactive elements (238U, 232Th and 40K) were determined in soil samples collected from 12 different locations in Ayranci region by using a NaI(Tl) gamma-ray spectrometer. The measured activity concentrations of the natural radionuclides in studied soil samples were compared with the corresponding results of different countries and the internationally reported values. From the analysis, it is found that these materials may be safely used as construction materials and do not pose significant radiation hazards.

Testing deep-sea biodiversity paradigms on abyssal nematode genera and Acantholaimus species

Science.gov (United States)

Lins, Lidia; da Silva, Maria Cristina; Neres, Patrícia; Esteves, André Morgado; Vanreusel, Ann

2018-02-01

Biodiversity patterns in the deep sea have been extensively studied in the last decades. In this study, we investigated whether reputable concepts in deep-sea ecology also explain diversity and distribution patterns of nematode genera and species in the abyss. Among them, three paradigms were tackled: (1) the deep sea is a highly diverse environment at a local scale, while on a regional and even larger geographical scale, species and genus turnover is limited; (2) the biodiversity of deep-sea nematode communities changes with the nature and amount of organic matter input from the surface; and (3) patch-mosaic dynamics of the deep-sea environment drive local diversity. To test these hypotheses, diversity and density of nematode assemblages and of species of the genus Acantholaimus were studied along two abyssal E-W transects. These two transects were situated in the Southern Ocean ( 50°S) and the North Atlantic ( 10°N). Four different hierarchical scales were used to compare biodiversity: at the scale of cores, between stations from the same region, and between regions. Results revealed that the deep sea harbours a high diversity at a local scale (alpha diversity), but that turnover can be shaped by different environmental drivers. Therefore, these results question the second part of the paradigm about limited species turnover in the deep sea. Higher surface primary productivity was correlated with greater nematode densities, whereas diversity responses to the augmentation of surface productivity showed no trend. Areas subjected to a constant and low food input revealed similar nematode communities to other oligotrophic abyssal areas, while stations under high productivity were characterized by different dominant genera and Acantholaimus species, and by a generally low local diversity. Our results corroborate the species-energy hypothesis, where productivity can set a limit to the richness of an ecosystem. Finally, we observed no correlation between sediment

root nematode control and crop yield

African Journals Online (AJOL)

SARAH

2016-05-31

May 31, 2016 ... The relationship between cost and benefit of the nematicide applications was also estimated. ... based on nematode threshold (100 nematodes per g of fresh root) which resulted in two applications; ..... France. Araya M, 2004. Situación actual del manejo de nematodos en banano (Musa AAA) y plátano.

77 FR 22185 - Golden Nematode; Removal of Regulated Areas

Science.gov (United States)

2012-04-13

...-0036] Golden Nematode; Removal of Regulated Areas AGENCY: Animal and Plant Health Inspection Service..., without change, an interim rule that amended the golden nematode regulations by removing the townships of... that the fields in these two townships are free of golden nematode, and we determined that regulation...

Plant actin cytoskeleton re-modeling by plant parasitic nematodes.

Science.gov (United States)

Engler, Janice de Almeida; Rodiuc, Natalia; Smertenko, Andrei; Abad, Pierre

2010-03-01

The cytoskeleton is an important component of the plant's defense mechanism against the attack of pathogenic organisms. Plants however, are defenseless against parasitic root-knot and cyst nematodes and respond to the invasion by the development of a special feeding site that supplies the parasite with nutrients required for the completion of its life cycle. Recent studies of nematode invasion under treatment with cytoskeletal drugs and in mutant plants where normal functions of the cytoskeleton have been affected, demonstrate the importance of the cytoskeleton in the establishment of a feeding site and successful nematode reproduction. It appears that in the case of microfilaments, nematodes hijack the intracellular machinery that regulates actin dynamics and modulate the organization and properties of the actin filament network. Intervening with this process reduces the nematode infection efficiency and inhibits its life cycle. This discovery uncovers a new pathway that can be exploited for the protection of plants against nematodes.

Unraveling flp-11/flp-32 dichotomy in nematodes.

Science.gov (United States)

Atkinson, Louise E; Miskelly, Iain R; Moffett, Christy L; McCoy, Ciaran J; Maule, Aaron G; Marks, Nikki J; Mousley, Angela

2016-10-01

FMRFamide-like peptide (FLP) signalling systems are core to nematode neuromuscular function. Novel drug discovery efforts associated with nematode FLP/FLP receptor biology are advanced through the accumulation of basic biological data that can reveal subtle complexities within the neuropeptidergic system. This study reports the characterisation of FMRFamide-like peptide encoding gene-11 (flp-11) and FMRFamide-like peptide encoding gene-32 (flp-32), two distinct flp genes which encode the analogous peptide, AMRN(A/S)LVRFamide, in multiple nematode species - the only known example of this phenomenon within the FLPergic system of nematodes. Using bioinformatics, in situ hybridisation, immunocytochemistry and behavioural assays we show that: (i) flp-11 and -32 are distinct flp genes expressed individually or in tandem across multiple nematode species, where they encode a highly similar peptide; (ii) flp-11 does not appear to be the most widely expressed flp in Caenorhabditis elegans; (iii) in species expressing both flp-11 and flp-32, flp-11 displays a conserved, restricted expression pattern across nematode clades and lifestyles; (iv) in species expressing both flp-11 and flp-32, flp-32 expression is more widespread and less conserved than flp-11; (v) in species expressing only flp-11, the flp-11 expression profile is more similar to the flp-32 profile observed in species expressing both; and (vi) FLP-11 peptides inhibit motor function in multiple nematode species. The biological significance and evolutionary origin of flp-11 and -32 peptide duplication remains unclear despite attempts to identify a common ancestor; this may become clearer as the availability of genomic data improves. This work provides insight into the complexity of the neuropeptidergic system in nematodes, and begins to examine how nematodes may compensate for structural neuronal simplicity. From a parasite control standpoint, this work underscores the importance of basic biological data, and has

Adhering Pasteuria penetrans endospores affect movements of root-knot nematode juveniles

Directory of Open Access Journals (Sweden)

Ioannis VAGELAS

2013-01-01

Full Text Available Pasteuria penetrans is a biological control agent of root-knot nematodes (Meloidogyne spp., preventing root invasion by second-stage juveniles (J2s, and eventually causing females sterility and death. greatest control effects for P. penetrans depend on the numbers of endospores attached to nematode cuticles. a method based on digital image analysis was used to record the effects of endospore attachment on the movements of juvenile root-knot nematodes, using a model based on the centroid point. Data showed that the numbers of endospores attached to the cuticle influenced nematode movement. At high endospore attachment levels (20‒30 per J2, nematodes did not show directional movement, whereas nematodes encumbered with five to eight spores showed limited directional movement, compared to those without endospores. nematode cephalic region turns were modelled using a markov chain, showing that P. penetrans endospores affected movements. Less nematodes invaded and established on tomato root systems when encumbered with low (five to eight or high numbers (20‒30 of P. penetrans endospores, compared with unencumbered nematodes.

Novel RNA viruses within plant parasitic cyst nematodes.

Science.gov (United States)

Ruark, Casey L; Gardner, Michael; Mitchum, Melissa G; Davis, Eric L; Sit, Tim L

2018-01-01

The study of invertebrate-and particularly nematode-viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies.

76 FR 60357 - Golden Nematode; Removal of Regulated Areas

Science.gov (United States)

2011-09-29

.... APHIS-2011-0036] Golden Nematode; Removal of Regulated Areas AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION: Interim rule and request for comments. SUMMARY: We are amending the golden nematode... infested areas. Surveys have shown that the fields in these two townships are free of golden nematode, and...

Naturally occurring radioactive materials at New South Wales mines

International Nuclear Information System (INIS)

McLaughlin, Robert

2013-01-01

Until recently mines in New South Wales have been largely exempt from the provisions of the Radiation Control Act with respect to radioactive ore being mined and processed. Legislative changes and the national harmonisation efforts for mine safety regulation have drawn attention to the emerging issue of naturally occurring radioactive material (NORM). While mine operators are already obliged under their duty of care to manage this hazard, specific control measures are increasingly expected by the community and regulators. This applies throughout the whole mine life cycle from exploration right through to rehabilitation.

The pinewood nematode, Bursaphelenchus xylophilus

OpenAIRE

Mota, Manuel; Vieira, Paulo

2004-01-01

According to the European Plant Protection Organization, the pinewood nematode (PWN), Bursaphelenchus xylophilus is a quarantine organism at the top of the list of the pathogenic species. PWN may be found in North America (Canada, USA and Mexico) and in East Asia (Japan, Korea, China and Taiwan) and has a highly destructive capability towards conifers, in a relatively short time, causing serious economic damage in Japan, China and Korea. This nematode surveying is extremely imp...

Behavioral changes in freestall-housed dairy cows with naturally occurring clinical mastitis

DEFF Research Database (Denmark)

Fogsgaard, Katrine Kop; Bennedsgaard, Torben Werner; Herskin, Mette S

2015-01-01

Dairy cows exhibit classic signs of sickness behavior during mastitis. However, knowledge about the consequences of naturally occurring mastitis in freestall-housed dairy cows, milked in automatic milking systems, is lacking. The aim of the present study was to describe the behavior of dairy cows...... after diagnosis and antibiotic treatment of mastitis. In the days before and after antibiotic treatment, the milking behavior, feeding, and activity were examined in 30 mastitic and 30 control Danish Holstein-Friesian cows kept in freestalls and milked by an automatic milking system. Sickness behavior...... milking, as seen by a higher frequency of tripping and kicking. Mastitic cows continued to show increased kicking during milking even after the antibiotic treatment period. These results show that the behavioral changes induced by naturally occurring mastitis persisted beyond the days of antibiotic...

Entomopathogenic and plant pathogenic nematodes as opposing forces in agriculture.

Science.gov (United States)

Kenney, Eric; Eleftherianos, Ioannis

2016-01-01

Plant-parasitic nematodes are responsible for substantial damages within the agriculture industry every year, which is a challenge that has thus far gone largely unimpeded. Chemical nematicides have been employed with varying degrees of success, but their implementation can be cumbersome, and furthermore they could potentially be neutralising an otherwise positive effect from the entomopathogenic nematodes that coexist with plant-parasitic nematodes in soil environments and provide protection for plants against insect pests. Recent research has explored the potential of employing entomopathogenic nematodes to protect plants from plant-parasitic nematodes, while providing their standard degree of protection against insects. The interactions involved are highly complex, due to both the three-organism system and the assortment of variables present in a soil environment, but a strong collection of evidence has accumulated regarding the suppressive capacity of certain entomopathogenic nematodes and their mutualistic bacteria, in the context of limiting the infectivity of plant-parasitic nematodes. Specific factors produced by certain entomopathogenic nematode complexes during the process of insect infection appear to have a selectively nematicidal, or at least repellant, effect on plant-parasitic nematodes. Using this information, an opportunity has formed to adapt this relationship to large-scale, field conditions and potentially relieve the agricultural industry of one of its most substantial burdens. Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil

Directory of Open Access Journals (Sweden)

Fernanda Ramos

2016-04-01

Full Text Available Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70–100 calves or more of both genders with ≥200 eggs per gram of feces (EPG (sensitivity of 50 EPG. These calves were distributed into 10 groups (of 7–10 animals per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7–10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different

BASIDIOMYCETE-BASED METHOD FOR BIOCONTROL OF PHYTOPATHOGENIC NEMATODES

Directory of Open Access Journals (Sweden)

Tiberius BALAEŞ

2015-12-01

Full Text Available Phytopathogenic nematodes represent one of the most important groups of pathogens in crops. The use of chemical to control the nematodes attack in crops is decreasing every year due to the concern of the toxicity and side effects of such compounds. In the course for finding alternatives to the use of chemicals, biological control of nematodes is gaining much attention. Some saprotrophic fungi are able to feed on invertebrates, thus becoming efficient agents of control. In this study, three species of basidiomycetes were analyzed for their potential to be used as control agents of phytopathogenic nematodes. Through on in vitro investigation of these potential, one strain – Gymnopilus junonius was further selected for a pot test against Meloidogyne incognita, a very important phytopathogenic species of nematodes. The fungal treatment strongly decreased the M. incognita population on the tested pots, proving the potential of G. junonius strain to be used in biocontrol.

Gamma ray doses proceeding from natural occurring radionuclides in closed environments

International Nuclear Information System (INIS)

Aguiar, Vitor Angelo P. de; Medina, Nilberto H.; Silveira, Marcilei A. Guazzelli da; Moreira, Ramon H.

2009-01-01

In this work we report on the application of gamma-ray spectrometry in the study of the effective dose coming from terrestrial natural elements present in building materials such as sand, cement, lime (CaO) and milled granitic stones. The major contribution to annual gamma-ray radiation effective dose is due to the natural occurring radionuclides 40 K, 232 Th and 238 U. Two spectrometry systems were employed to measure the gamma radiation: one with a 60% efficient GeHP detector and the second one with a 2''x2'' NaI(Tl) scintillator. The estimated effective dose coming from the three reference rooms assumed is 0.63 mSv/yr, proceeding from terrestrial natural elements. The principal gamma radiation sources are cement, sand and bricks. (author)

Mercury in parasitic nematodes and trematodes and their double-crested cormorant hosts: Bioaccumulation in the face of sequestration by nematodes

Energy Technology Data Exchange (ETDEWEB)

Robinson, Stacey A., E-mail: srobinsc@connect.carleton.ca [Department of Biology, Carleton University, 209 Nesbitt Bldg, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada); Forbes, Mark R., E-mail: mforbes6@gmail.com [Department of Biology, Carleton University, 209 Nesbitt Bldg, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada); Hebert, Craig E., E-mail: Craig.Hebert@ec.gc.ca [Environment Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1A 0H3 (Canada)

2010-10-15

Endoparasites can alter their host's heavy metal concentrations by sequestering metals in their own tissues. Contracaecum spp. (a nematode), but not Drepanocephalus spathans (a trematode), were bioaccumulating mercury to concentrations 1.5 times above cormorant hosts. Nematodes did not have significantly greater stable nitrogen isotope values ({delta}{sup 15}N) than their hosts, which is contradictory to prey-predator trophic enrichment studies, but is in agreement with other endoparasite-host relationships. However, Contracaecum spp. {delta}{sup 13}C values were significantly greater than their hosts, which suggest that nematodes were consuming host tissues. Nematodes were accumulating and thus sequestering some of their cormorant hosts' body burden of methyl mercury; however, they were not dramatically reducing their hosts' accumulation of methyl mercury.

Potato crop growth as influenced by potato cyst nematodes (Globodera pallida) and abiotic factors

NARCIS (Netherlands)

Ruijter, de F.

1998-01-01

The objective of the research described in this thesis was to determine the major mechanisms by which potato cyst nematodes reduce potato crop growth and to explain interactions known to occur with cultivar and abiotic factors. Understanding of these interactions may lead to strategies that

Stem nematode counteracts plant resistance of aphids in alfalfa, Medicago sativa.

Science.gov (United States)

Ramirez, Ricardo A; Spears, Lori R

2014-10-01

Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. This study examined the effect of nematode-resistant varieties on aphid (Acyrthosiphon pisum) suppression, and then determined how infection by the stem nematode, Ditylenchus dipsaci, mediated ecological effects on aphids and on plant defense proteins. Four alfalfa (Medicago sativa) varieties were selected with resistance to nematodes only (+,-), aphids only (-,+), nematodes and aphids (+,+), and susceptibility to nematodes and aphids (-,-). Field and greenhouse experiments were conducted to isolate the effect of nematode infection and aphid abundance on each variety. We found that varieties resistant to nematode, regardless of aphid resistance, had the lowest aphid counts, suggesting possible cross-resistance. Aphid abundance, however, increased when plants were exposed to nematodes. Resistant varieties were associated with elevated saponins but these compounds were not affected by insect or pathogen feeding. Concentrations of peroxidases and trypsin inhibitors, however, were increased in nematode resistant varieties when exposed to nematodes and aphids, respectively. The patterns of plant defense were variable, and a combination of resistance traits and changes in nutrient availability may drive positive interactions between nematodes and aphids aboveground.

Naturally occurring radioactivity in the Nordic countries. Recommendations

International Nuclear Information System (INIS)

2000-01-01

In the publication 'Naturally Occurring Radiation in the Nordic Countries - Recommendations' published in 1986 the radiation protection authorities in Denmark, Finland, Iceland, Norway and Sweden gave radiation protection recommendations for natural radiation in the Nordic countries. The exposure of the populations in the Nordic countries to natural radiation sources is among the highest in the world and much effort has been devoted during the last 10 to 20 years to characterising, assessing and, where feasible, to reduce these exposures. The exposure of workers to natural radiation sources has also been an important area of work in the same period. During this period the international recommendations on radiation protection policy have been further developed with ICRP Publication 60: '1990 Recommendations of the International Commission on Radiological Protection', and ICRP Publication 65: 'Protection Against Radon-222 at Home and at Work'. The European Basic Safety Standards Directive from 1996 (96/29/EURATOM), which is based on the ICRP recommendations, differs from the earlier versions in that special provisions have been laid down concerning exposure to natural radiation sources. As Denmark, Finland and Sweden are members of European Union and the EFTA-countries (Iceland and Norway) have close co-operation with the EU, the practical implementation of the EU-BSS will play an important role in all the Nordic countries. In November 1998, a new Drinking Water Directive, 98/83/EC, was adopted. The directive also includes radioactivity in drinking water, excluding potassium-40, radon, and radon decay products. Altogether this means that the Nordic recommendations from 1986 for natural radiation needed to be updated. The Nordic Radiation Protection Authorities therefore decided to set up a working group with the aim of revising the recommendations from 1986. The new revised recommendations will, as before, only deal with the components of the exposure to natural

Early responses of resistant and susceptible potato roots during invasion by the potato cyst nematode Globodera rostochiensis.

Science.gov (United States)

Sheridan, Jacqueline P; Miller, Anthony J; Perry, Roland N

2004-03-01

Signals from roots of resistant (cv. Maris Piper) and susceptible (cv. Désirée) potato cultivars during invasion by second stage juveniles (J2s) of the potato cyst nematode, Globodera rostochiensis, were investigated. Novel experimental chambers enabled the recording of electrophysiological responses from roots during nematode invasion. The root cell membrane potentials were maintained throughout the 3 d required to assess invasion and feeding site development. The steady-state resting membrane potentials of Désirée were more negative than those of Maris Piper on day 1, but the reverse on day 3. After 5 d there was no difference between the two cultivars. Intracellular microelectrodes detected marked spike activity in roots after the application of J2s and there were distinct and reproducible differences between the two cultivars, with the response from Désirée being much greater than that from Maris Piper. The responses to mechanical stimulation of roots by blunt micropipettes and sharp electrodes were consistent and similar in both cultivars to the responses in Maris Piper obtained after nematode invasion, but could not account for the marked response found in Désirée. Exogenous application of exoenzymes, used to mimic nematode chemical secretions, resulted in a distinct depolarization pattern that, although similar in both cultivars, was different from patterns obtained during nematode invasion or mechanical stimulation. The pH of homogenates prepared from roots of both cultivars was measured and a Ca2+ channel blocker was used to assess the role of Ca2+ in nematode invasion. The results indicated a role for Ca2+ in the signalling events that occur during nematode invasion.

Relationship between production, nematodes and "redness" in strawberries

Directory of Open Access Journals (Sweden)

Paula Nogueira Curi

2016-08-01

Full Text Available ABSTRACT: In recent years "redness" has increasingly appeared in strawberry plants with leaves taking on a reddish color. No causal agent has been associated with plants. Since strawberries presented problems due to the incidence of nematodes, the purpose of this study was to look at the relationship between production, resistance to the Meloidogyne hapla nematode and the "redness" symptom in strawberry cultivars. Two experiments were performed, both with the 'Camino Real', 'Festival', 'Oso Grande', 'Albion' and 'Camarosa' cultivars. The first experiment was performed in the field, where the following were evaluated: strawberry production, fruit quality, macro and micronutrient contents in fruit and leaves, percentage of plant survival, incidence of nematodes, quantity of eggs in the roots and juveniles in the soil, and the incidence of Botrytis cinerea . In the second experiment, the strawberries were transplanted into pots and filled with pinus bark-based commercial substrate. Half the pots were inocculated with Meloidogyne hapla . Cultivars presented differences in fruit production and also in the incidence of "redness". Lowest performance in production was related to the high incidence of the nematode Meloidogyne hapla. 'Oso Grande' and 'Albion' presented nematode-resistant behavior. It was possible find a relationship between the incidence of the Meloidogyne hapla nematode, and the incidence of "redness" only 'Camino Real' cultivar.

Immunomodulatory effects in workers exposed to naturally occurring asbestos fibers.

Science.gov (United States)

Ledda, Caterina; Costa, Chiara; Matera, Serena; Puglisi, Beatrice; Costanzo, Valentina; Bracci, Massimo; Fenga, Concettina; Rapisarda, Venerando; Loreto, Carla

2017-05-01

Natural asbestiform fibers are defined 'naturally occurring asbestos' (NOA) and refer to the mineral as a natural component of soils or rocks. The release of NOA fibers into the air from rocks or soils by routine human activities or natural weathering processes represents a risk for human beings. Fluoro-edenite (FE) is a NOA fiber detected in the benmoreitic lava in the area of Biancavilla, South-west slope of Mt. Etna. The aim of the present study was to investigate FE immunotoxicity pathways in a group of 38 occupationally exposed construction workers, in order to find any biological markers of its effect. Subjects underwent respiratory function tests and HRCT total chest scanning. Serum IL-1β, IL-6, IL-8 and TNF-α were measured. The presence of PPs was significantly greater in subjects exposed than in the control (25 vs. 2). In subjects exposed to FE, IL-1β and TNF-α values were significantly higher than the controls. The previously observed increase of IL-1β and IL-18 showed a probable involvement of the proteic complex defined inflammosome by FE fibers.

APPLICATION OF THE NATURALLY-OCCURRING DEUTERIUM ISOTOPE TO TRACING THE CAPILLARY FRINGE

Science.gov (United States)

Naturally-occurring deuterium is a useful tracer of subsurface hydrologic processes. A possible application includes the identification of capillary fringes in the vadose zone. Multiple and discontinuous water tables persist in many temperate regions, under various hydrogeologi...

Apoplastic Venom Allergen-like Proteins of Cyst Nematodes Modulate the Activation of Basal Plant Innate Immunity by Cell Surface Receptors

Science.gov (United States)

Lozano-Torres, Jose L.; Wilbers, Ruud H. P.; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C.; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert

2014-01-01

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize

Apoplastic venom allergen-like proteins of cyst nematodes modulate the activation of basal plant innate immunity by cell surface receptors.

Science.gov (United States)

Lozano-Torres, Jose L; Wilbers, Ruud H P; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert

2014-12-01

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize

Apoplastic venom allergen-like proteins of cyst nematodes modulate the activation of basal plant innate immunity by cell surface receptors.

Directory of Open Access Journals (Sweden)

Jose L Lozano-Torres

2014-12-01

Full Text Available Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes

Interaction between manufactured gold nanoparticles and naturally occurring organic macromolecules

International Nuclear Information System (INIS)

Diegoli, Sara; Manciulea, Adriana L.; Begum, Shakiela; Jones, Ian P.; Lead, Jamie R.; Preece, Jon A.

2008-01-01

The increasing exploitation of nanomaterials into many consumer and other products is raising concerns as these nanomaterials are likely to be released into the environment. Due to our lack of knowledge about the environmental chemistry, transport and ecotoxicology of nanomaterials, it is of paramount importance to study how natural aquatic colloids can interact with manufactured gold nanoparticles as these interactions will determine their environmental fate and behaviour. In this context, our work aims to quantify the effect of naturally occurring riverine macromolecules - International Humic Substances Society (IHSS) Suwannee River Humic Acid Standard (SRHA) - on citrate- and acrylate-stabilized gold nanoparticles. The influence of SRHA on the stability of the gold colloids was studied as a function of pH by UV-visible absorption spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). At high ionic strengths (0.1 M), extensive and rapid aggregation occurred, while more subtle effects were observed at lower ionic strength values. Evidence was found that SRHA enhances particle stability at extreme pH values (ionic strength < 0.01 M) by substituting and/or over-coating the original stabilizer on the gold nanoparticle surface, thus affecting surface charge and chemistry. These findings have important implications for the fate and behaviour of nanoparticles in the environment and their ecotoxicity

Cyst nematode-induced changes in plant development

NARCIS (Netherlands)

Goverse, A.

1999-01-01

This thesis describes a first attempt to investigate the biological activity of cyst nematode secretions on plant cell proliferation and the molecular mechanisms underlying feeding cell development in plant roots upon cyst nematode infection.

To investigate the role of

Anthelmintic resistance in equine nematodes

Directory of Open Access Journals (Sweden)

Jacqueline B. Matthews

2014-12-01

Full Text Available Anthelmintics have been applied indiscriminately to control horse nematodes for over 40 years. Three broad-spectrum anthelmintic classes are currently registered for nematode control in horses: benzimidazoles (fenbendazole, oxibendazole, tetrahydropyrimidines (pyrantel and macrocyclic lactones (ivermectin, moxidectin. Generally, control strategies have focused on nematode egg suppression regimens that involve the frequent application of anthelmintics to all horses at intervals based on strongyle egg reappearance periods after treatment. The widespread use of such programmes has substantially reduced clinical disease, especially that associated with large strongyle species; however, high treatment frequency has led to considerable selection pressure for anthelmintic resistance, particularly in cyathostomin species. Field studies published over the last decade indicate that benzimidazole resistance is widespread globally in cyathostomins and there are also many reports of resistance to pyrantel in these worms. Cyathostomin resistance to macrocyclic lactone compounds is emerging, principally measured as a reduction in strongyle egg reappearance time observed after treatment. Ivermectin resistance is a further concern in the small intestinal nematode, Parascaris equorum, an important pathogen of foals. These issues indicate that horse nematodes must now be controlled using methods less dependent on anthelmintic use and more reliant on management practices designed to reduce the force of infection in the environment. Such strategies include improved grazing management integrated with targeted anthelmintic administration involving faecal egg count (FEC-directed treatments. The latter require that the supporting diagnostic tests available are robust and practically applicable. Recent research has focused on maximising the value of FEC analysis in horses and on optimizing protocols for anthelmintic efficacy testing. Other studies have sought to develop

Changes in soil nematode communities under the impact of fertilizers

Science.gov (United States)

Gruzdeva, L. I.; Matveeva, E. M.; Kovalenko, T. E.

2007-06-01

Changes taking place in the communities of soil nematodes of an artificially sown meadow under the impact of annually applied mineral fertilizers have been studied in a field experiment for nine years. It is shown that changes in the species composition, trophic structure, and numbers of nematodes from different genera depend on the fertilizer applied and on the competitiveness of the plant species grown. The spectra of nematode genera sensitive to the complete mineral fertilizer (NPK) and to the particular nutrients have been identified with the use of a number of parameters, including the maturity index of nematode communities, the biotope preferences of the particular nematode genera, and the general pattern of nematode habitats. The results obtained in this study can be used to assess the effect of mineral fertilizers on the soil fauna and to suggest optimum application rates of mineral fertilizers ensuring the sustainable development of meadow herbs. The use of the data on the trophic structure of nematode communities for predicting the ways of organic matter decomposition in the soil is discussed.

High-throughput sequencing of nematode communities from total soil DNA extractions

DEFF Research Database (Denmark)

Sapkota, Rumakanta; Nicolaisen, Mogens

2015-01-01

nematodes without the need for enrichment was developed. Using this strategy on DNA templates from a set of 22 agricultural soils, we obtained 64.4% sequences of nematode origin in total, whereas the remaining sequences were almost entirely from other metazoans. The nematode sequences were derived from...... in previous sequence-based studies are not nematode specific but also amplify other groups of organisms such as fungi and plantae, and thus require a nematode enrichment step that may introduce biases. Results: In this study an amplification strategy which selectively amplifies a fragment of the SSU from...... a broad taxonomic range and most sequences were from nematode taxa that have previously been found to be abundant in soil such as Tylenchida, Rhabditida, Dorylaimida, Triplonchida and Araeolaimida. Conclusions: Our amplification and sequencing strategy for assessing nematode diversity was able to collect...

Challenges for mass production of nematodes in submerged culture.

Science.gov (United States)

de la Torre, Mayra

2003-08-01

Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.

Induction of interleukin 1 by synthetic and naturally occurring muramyl peptides.

Science.gov (United States)

Dinarello, C A; Krueger, J M

1986-10-01

Like bacterial lipopolysaccharides (endotoxins), synthetic muramyl peptides (MPs) are thought to exert many of their biological effects by inducing the production of various mediators from host cells. Both synthetic muramyl dipeptide (MDP) and naturally occurring sleep factor (SF), which contains an MP structure, stimulate human monocytes to produce interleukin 1 (IL 1). IL 1 is a family of unique polypeptides that mediate a variety of host defense functions and possess several biological properties, many of which are shared with MPs. Endotoxins are potent inducers of IL 1, but polymyxin B, which blocks endotoxin's biological activities, has no effect on MP-induced IL 1 production. SF purified from human urine and SF isolated from the peritoneal fluid of patients undergoing chronic ambulatory peritoneal dialysis (CAPD) induce IL 1 when incubated with human mononuclear cells in vitro. SF from urine or CAPD fluid induces IL 1 production in the picrogram per milliliter range whereas synthetic MDP requires microgram per milliliter concentrations. Thus, both synthetic and naturally occurring MPs exert their biological effects, in part, by inducing IL 1.

Benthic freshwater nematode community dynamics under conditions ...

African Journals Online (AJOL)

Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr El-Sheikh Governorate, Egypt, ...

Scenarios identified internationally for occupational and public exposure to naturally occurring radioactive materials

International Nuclear Information System (INIS)

Fernandez Gomez, Isis Maria

2012-01-01

Natural radiation for decades was considered a normal phenomenon that existed in nature, so that man was conditioned to ignore; unlike artificial ionizing radiation. This mindset has changed, in the late seventies of the last century, because it has became aware of the danger that exposure to natural radiation could pose health. Studies on it have been initiated to conduct and publish. All humans are exposed to natural radiation; but, this exposure is not uniform, has depended on where they live and work, whether they have been in areas with rocks or soils particularly radioactive, their way of life, of the use of certain building materials in their homes, the use of natural gas, the use of home heating with coal. Air travel also have increased exposure to natural radiation. Ionizing radiation, whether natural or artificial, have interacted with the human body in the same way, there fore have failed to say that the natural are less or more harmful than artificial. Natural sources are grouped into two major categories. The first are the external sources: from abroad as cosmic radiation (the sun and interstellar spaces of the universe), terrestrial radiation (emitted by rocks and soil), the radiation of some buildings (e.g. granite, which can emit radon gas) and radiation contained in some foods. The second category are the internal resources: due to the presence in the human body from the environment radionuclides that are able to ionize (potassium-40, carbon-14). The naturally occurring radioactive materials (NORM for its acronym in English) have been referred to those naturally occurring radioactive materials on which any human technological activity has increased its exposure potential compared with the situation unchanged. (author) [es

Nematode taxonomy: from morphology to metabarcoding

Science.gov (United States)

Ahmed, M.; Sapp, M.; Prior, T.; Karssen, G.; Back, M.

2015-11-01

Nematodes represent a species rich and morphologically diverse group of metazoans inhabiting both aquatic and terrestrial environments. Their role as biological indicators and as key players in nutrient cycling has been well documented. Some groups of nematodes are also known to cause significant losses to crop production. In spite of this, knowledge of their diversity is still limited due to the difficulty in achieving species identification using morphological characters. Molecular methodology has provided very useful means of circumventing the numerous limitations associated with classical morphology based identification. We discuss herein the history and the progress made within the field of nematode systematics, the limitations of classical taxonomy and how the advent of high throughput sequencing is facilitating advanced ecological and molecular studies.

Parasitic nematode interactions with mammals and plants.

Science.gov (United States)

Jasmer, Douglas P; Goverse, Aska; Smant, Geert

2003-01-01

Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent reinfection of host species. In addition, development of resistance to nematicides and anthelmintics by these parasites and reduced availability of some nematicides, for environmental protection, pose significant obstacles for current and future prospects of effective parasite control. Due to marked differences in host species, research on animal and plant parasitic nematodes often proceeds independently. Despite the differences between animals and plants, basic cellular properties are shared among these host organisms. Some common properties may be important for mechanisms [homologous or convergent (homoplastic)] by which nematodes successfully infect these diverse hosts or by which animal and plant hosts resist infections by these pathogens. Here we compare host/parasite interactions between plant parasitic nematodes (PPN) and animal parasitic nematodes, with an emphasis on mammalian hosts (MPN). Similarities and differences are considered in the context of progress on molecular dissection of these interactions. A comprehensive coverage is not possible in the space allotted. Instead, an illustrative approach is used to establish examples that, it is hoped, exemplify the value of the comparative approach.

[Nematodes (Nematoda) from bats (Chiroptera) of the Samarskaya Luka Peninsula (Russia)].

Science.gov (United States)

Kirillova, N Iu; Kirillov, A A; Vekhnik, V P

2008-01-01

Fauna of parasitic nematodes from Chiroptera of the Samarskaya Luka has been studied. Seven nematode species has been recorded. Numbers of host specimens, indices of extensiveness and intensiveness of the invasion, parasite abundance, and brief characteristics of the nematode species are given. Some nematode species were for the first time recorded in bats of Russia.

Effect of urea-molasses block supplementation on grazing weaner goats naturally infected with gastrointestinal nematodes

Directory of Open Access Journals (Sweden)

R.M. Waruiru

2004-11-01

Full Text Available The influence of feeding urea-molasses blocks (UMB on growth and gastrointestinal (GI nematode parasitism of weaner goats grazing the same pasture was investigated on a farm in Nyandarua District, Kenya. Thirty female Small East African goat kids at an average age of 5 months were initially treated with albendazole orally (5 mg kg-1 body mass and randomly assigned into one of two groups: group I were fed UMB prepared using a cold process and group II kids (controls received no block supplementation (NBS. The UMB were given in the evening when the animals returned from grazing and were consumed during the night at a rate of 95.0 g head-1 day-1. Supplementation was undertaken for 3 consecutive months from July to September 2001 and January to March 2002. Body mass of the kids and faecal egg counts were measured monthly and larval cultures were performed on positive faecal samples of kids of each group. Five goats from each group were randomly selected for slaughter and total counts and identification of worms at the end of June 2002. Significant differences (P < 0.05 were found in cumulative mass gains of kids in group I from September compared with those in group II. On termination of the study kids in group I had gained an average of (+ SD 20.4 ± 1.4 kg while those in group II had gained 11.8 + 1.1 kg. From January 2002, faecal egg counts of the kids in the UMB group differed significantly (P < 0.05 from those of the NBS group and at slaughter, the mean (+ SD worm counts for the UMB group was 482 + 299 while that of the NBS group was 1 302 + 410. In all the goats, Haemonchus contortus was the predominant nematode recovered. These results indicate that UMB had significant effects in the control of GI nematode parasitism and enhanced growth of the young goats.

Evaluation of efficacy of entomopathogenic nematodes against larvae of Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae).

Science.gov (United States)

Tóth, Erika M; Márialigeti, K; Fodor, A; Lucskai, A; Farkas, R

2005-01-01

The blowfly Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) is the primary agent of cutaneous myiasis of sheep in northern Europe, southern Africa, Australia and New Zealand. As the application of chemicals has several disadvantages, alternative control measures of traumatic myiasis of livestock must be developed. In this study, the use of entomopathogenic nematodes (EPNs) as potential biocontrol agents against second instar larvae of Lucilia sericata was considered. The following nematode species were tested: Heterorhabditis bacteriophora (IS 5, HHU 1, Hmol, HNC 1, HAZ 36, Hbrecon, HHU 2, HAZ 29, HHP 88, HHU 3, HHU 4 and HGua), Steinernema intermedia, NC513 strain of S. glaserii, S. anomali, S. riobrave, Steinernema sp. and 5 strains of S. feltiae (22, Vija Norway, HU 1, scp, and IS 6). None of the examined EPN species or strains showed larvicidal efficacy at 37 degrees C (no killing effect was observed in the case of the two heat-tolerant strains--H. bacteriophora and S.feltiae) against L. sericata larvae. At lower temperatures (20 degrees C and 25 degrees C) only strains of S. feltiae were found to be active. The overall odds ratios calculated for L. sericata maggots to contract S. feltiae nematode infection show significant (p nematode occurred in the cadavers.

Disruption of prefoldin-2 protein synthesis in root-knot nematodes via host-mediated gene silencing efficiently reduces nematode numbers and thus protects plants.

Science.gov (United States)

Ajjappala, Hemavathi; Chung, Ha Young; Sim, Joon-Soo; Choi, Inchan; Hahn, Bum-Soo

2015-03-01

The aim of this study is to demonstrate the feasibility of down-regulating endogeneous prefoldin-2 root-knot nematode transcripts by expressing dsRNA with sequence identity to the nematode gene in tobacco roots under the influence of strong Arabidopsis ubiquitin (UBQ1) promoter. Root-knot nematodes (RKNs) are sedentary endoparasites infecting a wide range of plant species. They parasitise the root system, thereby disrupting water and nutrient uptake and causing major reductions in crop yields. The most reliable means of controlling RKNs is via the use of soil fumigants such as methyl bromide. With the emergence of RNA interference (RNAi) technology, which permits host-mediated nematode gene silencing, a new strategy to control plant pathogens has become available. In the present study, we investigated host-induced RNAi gene silencing of prefoldin-2 in transgenic Nicotiana benthamiana. Reductions in prefoldin-2 mRNA transcript levels were observed when nematodes were soaked in a dsRNA solution in vitro. Furthermore, nematode reproduction was suppressed in RNAi transgenic lines, as evident by reductions in the numbers of root knots (by 34-60 % in independent RNAi lines) and egg masses (by 33-58 %). Endogenous expression of prefoldin-2, analysed via real-time polymerase chain reaction and Western blotting, revealed that the gene was strongly expressed in the pre-parasitic J2 stage. Our observations demonstrate the relevance and potential importance of targeting the prefoldin gene during the nematode life cycle. The work also suggests that further improvements in silencing efficiency in economically important crops can be accomplished using RNAi directed against plant-parasitic nematodes.

Nematode-bacterium symbioses--cooperation and conflict revealed in the "omics" age.

Science.gov (United States)

Murfin, Kristen E; Dillman, Adler R; Foster, Jeremy M; Bulgheresi, Silvia; Slatko, Barton E; Sternberg, Paul W; Goodrich-Blair, Heidi

2012-08-01

Nematodes are ubiquitous organisms that have a significant global impact on ecosystems, economies, agriculture, and human health. The applied importance of nematodes and the experimental tractability of many species have promoted their use as models in various research areas, including developmental biology, evolutionary biology, ecology, and animal-bacterium interactions. Nematodes are particularly well suited for the investigation of host associations with bacteria because all nematodes have interacted with bacteria during their evolutionary history and engage in a variety of association types. Interactions between nematodes and bacteria can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved, their study can provide broader insights into other types of associations, including those relevant to human diseases. Recently, genome-scale studies have been applied to diverse nematode-bacterial interactions and have helped reveal mechanisms of communication and exchange between the associated partners. In addition to providing specific information about the system under investigation, these studies also have helped inform our understanding of genome evolution, mutualism, and innate immunity. In this review we discuss the importance and diversity of nematodes, "omics"' studies in nematode-bacterial systems, and the wider implications of the findings.

Studies on Lasioseius scapulatus, a Mesostigmatid mite predaceous on nematodes

OpenAIRE

Imbriani, I.; Mankau, R.

1983-01-01

The life history and feeding habits of Lasioseius scapulatus, an ascid predator and potential biocontrol agent of nematodes, was examined. Reproduction was asexual, and the life cycle was 8-10 days at room temperature. Life history consisted of the egg, protonymph, deutonymph, and adult. Both nymphal stages and the adult captured and consumed nematodes. Two fungal genera and eight genera of nematodes were suitable food sources. Second-stage root-knot nematode juveniles were eaten, but eggs an...

Rapid identification of cyst (Heterodera spp., Globodera spp.) and root-knot (Meloidogyne spp.) nematodes on the basis of ITS2 sequence variation detected by PCR-single-strand conformational polymorphism (PCR-SSCP) in cultures and field samples

NARCIS (Netherlands)

Clapp, J.P.; Van der Stoel, C.D.; Van der Putten, W.H.

2000-01-01

Cyst and root-knot nematodes show high levels of gross morphological similarity. This presents difficulties for the study of their ecology in natural ecosystems. In this study, cyst and root-knot nematode species, as well as some ectoparasitic nematode species, were identified using the second

Effect of Acetic and Lactic Acid Mixtures on Control of Quarantine Nematode, Bursaphelenchus xylophilus, in Exporting Cymbidium

Directory of Open Access Journals (Sweden)

Yunhee Seo

2014-09-01

Full Text Available The mixture (MX of acetic acid (AA and lactic acid (LA was examined for its effectiveness in the control of the pine wood nematode Bursaphelenchus xylophilus contaminated in cymbidium culture medium. Nematode mortality in vitro was nearly 100% in AA and MX at the concentrations of 5.0-1.0% (pH 2.6 – 4.2 and in LA only at 5.0% (pH 3.5, but lowered at concentrations of 0.5-0.1% (pH 5.1-6.9 more significantly in LA than AA and MX. MX of most concentrations caused higher nematode mortality than the average response to AA and LA. All treatments of MX (0.5% and 0.25%, fosthiazate (standard and double concentrations and culture dilution of Paenibacillus polymyxa GBR-1 (107colony-forming units/ml reduced significantly the nematode populations in the cymbidium culture medium, compared to non-treatment control, with no significant difference among the treatments. No phytotoxicity occurred in all treatments. pH of the medium with the time after treatment and growths of 2-year-old cymbidium were not significantly different among treatments. Considering the safety and price of the organic acids, use of MX in the processes for culturing cymbidium may be a practically reliable and eco-friendly way in the control of the quarantine nematode in cymbidium.

Monitoring of increased natural occuring radiation exposure; Arbeitsplatzueberwachung bei erhoehter natuerlicher Strahlenexposition

Energy Technology Data Exchange (ETDEWEB)

Guhr, Andreas [ALTRAC Radon-Messtechnik, Berlin (Germany); Leissring, Nick [Bergtechnisches Ingenieurbuero GEOPRAX, Chemnitz (Germany)

2015-07-01

The radiation exposure due to natural occurring sources is a special challenge for the health and safety protection at workplaces. The monitoring of the radon exposure of employees in mines, radon-spa and in water works is regulated by prescription of radiation protection. The relevant compounds of the radiation exposure are the inhalation of radon and radon daughter products; terrestrial irradiation; ingestion of radioactive contaminated materials and the inhalation of contaminated dust. The monitoring of the radiation workers is realized essentially by measurements by radiation safety officer of the performing company, by an external engineering firm as well as by control measurements of experts of local authorities. The experiences in the practice have shown that in the field of operational radiation protection only a combination of personal- and operational dosimetry is suitable to avoid health hazards by work in fields with increased natural occurring radiation exposures.

Naturally occurring radioactive materials in construction integrating radiation protection in Reuse

CERN Document Server

Schroeyers, Wouter

2017-01-01

Naturally Occurring Radioactive Materials in Construction (COST Action NORM4Building) discusses the depletion of energy resources and raw materials and its huge impact not only on the building market, but also in the development of new synthetic building materials, whereby the reuse of various (waste) residue streams becomes a necessity. It is based on the outcome of COST Action TU 1301, where scientists, regulators, and representatives from industry have come together to present new findings, sharing knowledge, experiences, and technologies to stimulate research on the reuse of residues containing enhanced concentrates of natural radionuclides (NORM) in tailor-made building materials. Chapters address legislative issues, measurement, and assessment of building materials, physical and chemical aspects, from raw materials, to residues with enhanced concentrations of natural radionuclides (NORM), processes, building products containing NORM, and end-of-life and reuse requirements. Presents a holistic app...

Survey of nematodes associated with terrestrial slugs in Norway.

Science.gov (United States)

Ross, J L; Ivanova, E S; Hatteland, B A; Brurberg, M B; Haukeland, S

2016-09-01

A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identified by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in this study: Alloionema appendiculatum, Agfa flexilis, Angiostoma limacis, Angiostoma sp. and Phasmarhabditis hermaphrodita. Of these species, only one nematode was previously undescribed (Angiostoma sp.). This is the first record of the presence of A. appendiculatum, A. flexilis and A. limacis in Norway.

Management of the potato cyst nematode (Globodera pallida) with bio-fumigants/stimulants.

Science.gov (United States)

Martin, T J G; Turner, S J; Fleming, C C

2007-01-01

Field trials evaluated the effect of four plant-based bio-fumigants/stimulants on population levels of G. pallida and the resulting potato yields and quality. Three formulations contained seaweed biostimulants (Algifol, Nutridip and Metastim) and one bio-fumigant containing mustard and chilli pepper extracts (Dazitol). These were compared with the fumigant nematicide Nemathorin and untreated control plots. The effect of G. pallida on growing potato crops was assessed by recording haulm characteristics which indicated that the nematicide treatment gave most protection. Levels of PCN juveniles and migratory nematodes were assessed during the trial. Plots treated with Nemathorin and Dazitol had fewest PCN, whilst the highest number of migratory nematodes occurred in fallow plots. Sixteen weeks after planting the nematicide treatment produced highest yield and tuber numbers. Dazitol treatment produced a lower yield but the largest tubers.

Effect of mine tailing on the spatial variability of soil nematodes from lead pollution in La Union (Spain).

Science.gov (United States)

Rodríguez Martín, José Antonio; Gutiérrez, Carmen; Escuer, Miguel; García-González, Ma Teresa; Campos-Herrera, Raquel; Aguila, Nancy

2014-03-01

The Cartagena-La Union mining district, exploited since the end of the 3rd century BC, was one of the world's largest lead producers in the 19th century. Although activity ceased in 1991, today mining residues pose a huge pollution problem. This study characterises lead contents (total and DPTA) and other soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.) using multivariate geostatistical methods in relation to nematode diversity. In this work, trophic groups and metabolic footprints of soil nematodes were measured using 193 samples from the mining, natural and agricultural areas in this district. We explored the relationship between soil health and nematode communities. High lead concentrations were quantified: mean 8,500 mg kg(-1) for total and 340 mg kg(-1) for DPTA in this mining area. Although nematode diversity was broad (81 taxa), their diversity, abundance and metabolic footprints significantly reduced in the mining area. Significant differences in the nematode community structure were observed, and the relative abundance of predators was sensitive to mine and agricultural activities, whilst omnivores reduced only in the agricultural area, and bacterial feeders exhibited a differential response to both anthropogenic disturbances. The total abundance of nematodes, trophic groups and c-p groups correlated negatively with soil Pb contents, and a positive relationship was found with SOM and N, P and K contents. Copyright © 2013 Elsevier B.V. All rights reserved.

The complete mitochondrial genomes of three parasitic nematodes of birds: a unique gene order and insights into nematode phylogeny

Science.gov (United States)

2013-01-01

Background Analyses of mitochondrial (mt) genome sequences in recent years challenge the current working hypothesis of Nematoda phylogeny proposed from morphology, ecology and nuclear small subunit rRNA gene sequences, and raise the need to sequence additional mt genomes for a broad range of nematode lineages. Results We sequenced the complete mt genomes of three Ascaridia species (family Ascaridiidae) that infest chickens, pigeons and parrots, respectively. These three Ascaridia species have an identical arrangement of mt genes to each other but differ substantially from other nematodes. Phylogenetic analyses of the mt genome sequences of the Ascaridia species, together with 62 other nematode species, support the monophylies of seven high-level taxa of the phylum Nematoda: 1) the subclass Dorylaimia; 2) the orders Rhabditida, Trichinellida and Mermithida; 3) the suborder Rhabditina; and 4) the infraorders Spiruromorpha and Oxyuridomorpha. Analyses of mt genome sequences, however, reject the monophylies of the suborders Spirurina and Tylenchina, and the infraorders Rhabditomorpha, Panagrolaimomorpha and Tylenchomorpha. Monophyly of the infraorder Ascaridomorpha varies depending on the methods of phylogenetic analysis. The Ascaridomorpha was more closely related to the infraorders Rhabditomorpha and Diplogasteromorpha (suborder Rhabditina) than they were to the other two infraorders of the Spirurina: Oxyuridorpha and Spiruromorpha. The closer relationship among Ascaridomorpha, Rhabditomorpha and Diplogasteromorpha was also supported by a shared common pattern of mitochondrial gene arrangement. Conclusions Analyses of mitochondrial genome sequences and gene arrangement has provided novel insights into the phylogenetic relationships among several major lineages of nematodes. Many lineages of nematodes, however, are underrepresented or not represented in these analyses. Expanding taxon sampling is necessary for future phylogenetic studies of nematodes with mt genome

Nematode CLE signaling in Arabidopsis requires CLAVATA2 and CORYNE

Science.gov (United States)

Plant-parasitic cyst nematodes secrete CLAVATA3 (CLV3)/ESR(CLE)-like effector proteins. These proteins have been shown to act as ligand mimics of plant CLE peptides and are required for successful nematode infection; however, the receptors for nematode CLE-like peptides have not been identified. Her...

Bacterial microbiome and nematode occurrence in different potato agricultural soils

Science.gov (United States)

Pratylenchus neglectus and Meloidogyne chitwoodi are the main plant-parasitic nematodes in potato crops of the San Luis Valley, Colorado. Bacterial microbiome (16S rRNA copies per gram of soil) and nematode communities (nematodes per 200 gr of soil) from five different potato farms were analyzed to ...

7 CFR 301.85-9 - Movement of live golden nematodes.

Science.gov (United States)

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...

Naturally occurring radionuclides transfer factor on aquatic flora and fauna in Nagarjuna Sagar Dam near proposed uranium mining site

International Nuclear Information System (INIS)

Arunachalam, Kantha Deivi

2015-04-01

Naturally occurring radioactive element can be found in low levels within all rock, soil, and water. The present work aims to understand the transfer of naturally occurring radionuclides in different compartments of environment reflecting its behaviour in different tropic levels. The understanding and evaluation of the possible interactions of various naturally occurring radionuclides were done in the world's third largest man-made dam, Nagarjuna Sagar, built on river Krishna located in Andhra Pradesh, India. The naturally occurring radionuclides such as Uranium ( 238 U), Polonium ( 210 Po), Radium ( 226 Ra), and Lead ( 210 Pb) were analyzed in different matrices (i.e) sediment, water, and fish. The measurement of the naturally occurring radionuclides in the environment can be used as a reference baseline for long-term monitoring in the entire aquatic ecosystem

Naturally occurring arsenic in the groundwater at the Kansas City Plant

Energy Technology Data Exchange (ETDEWEB)

Korte, N.E.

1990-12-01

This report describes an investigation concerning the presence of arsenic in concentrations exceeding 0.4 mg/L in the groundwater under the Department of Energy's Kansas City Plant (KCP). The study consisted of four distinct phases: a thorough review of the technical literature, a historical survey of arsenic use at the facility, a laboratory study of existing techniques for determining arsenic speciation, and a field program including water, soil, and sediment sampling. The historical survey and literature review demonstrated that plant activities had not released significant quantities of arsenic to the environment but that similar occurrences of arsenic in alluvial groundwater are widespread in the midwestern United States. Laboratory studies showed that a chromatographic separation technique was necessary to accurately determine arsenic speciation for the KCP groundwater samples. Field studies revealed that naturally occurring reducing conditions prevalent in the subsurface are responsible for dissolving arsenic previously sorbed by iron oxides. Indeed, the data demonstrated that the bulk arsenic concentration of site subsoils and sediments is {approximately}7 mg/kg, whereas the arsenic content of iron oxide subsamples is as high as 84 mg/kg. Literature showed that similar concentrations of arsenic in sediments occur naturally and are capable of producing the levels of arsenic found in groundwater monitoring wells at the KCP. The study concludes, therefore, that the arsenic present in the KCP groundwater is the result of natural phenomena. 44 refs., 8 figs., 14 tabs.

Efficacy of an energy block containing Duddingtonia flagrans in the control of gastrointestinal nematodes of sheep.

Science.gov (United States)

Sagüés, María F; Fusé, Luis A; Fernández, Alicia S; Iglesias, Lucía E; Moreno, Fabiana C; Saumell, Carlos A

2011-09-01

The efficacy of the nematode-trapping fungus Duddingtonia flagrans incorporated into an energy block was evaluated for the control of gastrointestinal nematodes in sheep. Four naturally parasitised sheep with average nematode egg counts of 2,470 eggs per gram grazed by pairs on two similar parasite-free paddocks for 30 days. During that period, one pair of sheep (treated animals, T1) received an energy block containing chlamydospores of D. flagrans at a dose of 200,000 chlamydopores/kg bw/day, while the second pair (control animals, C1) received a fungus-free energy block. The animals in both groups were taken off the paddocks after contaminating the pastures for a month with either nematode eggs plus fungal chlamydospores (T1) or nematode eggs alone (C1). Twelve parasite-free sheep were divided into two groups of six animals each, the treated group (T2) was placed on the paddock previously contaminated with parasites and fungus, while the control group (C2) was placed on the parasite-only paddock. These two groups grazed on their respective paddocks during 30 days and were then housed for 15 days, after which period they were slaughtered in order to determine the parasite burden present in each animal. Results showed that animals in group T2 harboured significantly less nematodes than their counterpart in group C2. The efficacy of D. flagrans was 92% against the total parasite burden, 100% against Haemonchus contortus and Teladorsagia circumcincta, 89.9% against Trichostrongylus colubriformis, 87.5% against Cooperia onchopora, and 90% against Trichostrongylus axei. No efficacy was detected against Nematodirus spathiger, Trichuris ovis and T. skrjabini.

Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

Science.gov (United States)

Moens, Tom; Vafeiadou, Anna-Maria; De Geyter, Ellen; Vanormelingen, Pieter; Sabbe, Koen; De Troch, Marleen

2014-09-01

We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had δ13C indicating that MPB is their major carbon source. δ15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

Synthesis of the naturally occurring prenylated coumarins balsamiferone and cedrelopsin by domino reactions

Digital Repository Service at National Institute of Oceanography (India)

Patre, R.E.; Parameswaran, P.S.; Tilve, S.G.

Regioselective one step synthesis of naturally occurring prenyl coumarin balsamiferone is described using domino Wittig reaction, 3,3-sigmatropic rearrangements and deprenylation, while regioselective synthesis of cedrelopsin is described via domino...

Corrected simulations for one-dimensional diffusion processes with naturally occurring boundaries.

Science.gov (United States)

Shafiey, Hassan; Gan, Xinjun; Waxman, David

2017-11-01

To simulate a diffusion process, a usual approach is to discretize the time in the associated stochastic differential equation. This is the approach used in the Euler method. In the present work we consider a one-dimensional diffusion process where the terms occurring, within the stochastic differential equation, prevent the process entering a region. The outcome is a naturally occurring boundary (which may be absorbing or reflecting). A complication occurs in a simulation of this situation. The term involving a random variable, within the discretized stochastic differential equation, may take a trajectory across the boundary into a "forbidden region." The naive way of dealing with this problem, which we refer to as the "standard" approach, is simply to reset the trajectory to the boundary, based on the argument that crossing the boundary actually signifies achieving the boundary. In this work we show, within the framework of the Euler method, that such resetting introduces a spurious force into the original diffusion process. This force may have a significant influence on trajectories that come close to a boundary. We propose a corrected numerical scheme, for simulating one-dimensional diffusion processes with naturally occurring boundaries. This involves correcting the standard approach, so that an exact property of the diffusion process is precisely respected. As a consequence, the proposed scheme does not introduce a spurious force into the dynamics. We present numerical test cases, based on exactly soluble one-dimensional problems with one or two boundaries, which suggest that, for a given value of the discrete time step, the proposed scheme leads to substantially more accurate results than the standard approach. Alternatively, the standard approach needs considerably more computation time to obtain a comparable level of accuracy to the proposed scheme, because the standard approach requires a significantly smaller time step.

Evaluation of the Tolerance of Some Citrus Rootstocks to Citrus Nematode in Greenhouse (Tylenchulus semipenetrans

Directory of Open Access Journals (Sweden)

Y. Mohammad Alian

2018-02-01

rootstocks including Citromelo, Poncirus, Sour Orange, Bakraee, Rough lemon and Off-type some of these rootstocks are common citrus rootstocks in the North and south citrus regions of the present time, therefore it is necessary to choose appropriate rootstock. In addition to it, another purpose (aim of this research is to assess tolerance of new off-type biotype, produced from citrus breeding programs, to citrus nematode under greenhouse conditions in comparison with Citromelo, Poncirus, Sour Orange, Bakraee and Rough lemon which are common citrus rootstock in the North and South provinces of the country. Bakraee is one of the natural types of citrus used in citrus regions of Fars, Hormozgan and Kerman as rootstock of mandarin and orange cultivars for many years. Introductory surveys concerning Bakraee tolerance to coldness, the rot of crown and root, and diseases such as Tristeza, Exocortis and Cachexia were carried out but its tolerance to citrus nematode has not surveyed yet. Recent molecular surveys showed Bakraee relationship with Rough lemon beside, because of appearing unknown disease of citrus trees decline on Bakraee rootstock from the beginning of 1389 in Jiroft mountainous regions, doing etiology studies and investigating its tolerance to disease factors such as citrus nematode is of great importance. Since this nematode is soil parasite and can live in the depth of soil, its chemical control is very difficult. Despite the fact that one of the control methods of it is soil sterilization before citrus planting, but because of increasing environmental risks and bad effects on human health, it is recommended that resistant rootstocks such as Poncirus should be planted in the nematode soil. Also, it is necessary to control plants in selling time from the aspect of infection and, if necessary, to sterilize infected plants in order to prevent infection spread and build healthy orchards. Therefore regarding the fact that rootstocks of Poncirus and Citromelo are resistant

Ecology of the Pinewood Nematode in Southern Pine Chip Piles

Science.gov (United States)

L. David Dwinell

1986-01-01

The optimum temperature range for pinewood nematodes in southern pine chips was 35 to 40° C. Nematode populations declined at temperatures of -20°C. at temperatures above 45°C. and in anaerobic environments. Wood moisture content and presence of bluestain fungus also influenced nematode populations.

Mining the secretome of root-knot nematodes for cell wall modifying proteins

NARCIS (Netherlands)

Roze, E.H.A.

2008-01-01

The products of parasitism genes in nematodes must be secreted to reach their targets at the nematode-plant interface. These nematode secretory proteins are therefore recognised to play an important role in the nematode-plant interaction and as a result have been subject of intense study for years.

Determination of naturally occurring radionuclides in scales produced in oil industry

Energy Technology Data Exchange (ETDEWEB)

Al-Masri, M S; Ali, A F; Kitue, M; Kawash, A [Atomic Energy Commission, Dept. of Radiation Protection and Nuclear Safety, Damascus (Syrian Arab Republic)

1997-04-01

Scales produced by Oil production operations contain relatively high concentrations of natural radionuclides especially radium isotopes (Ra-226, Ra-228, Ra-224) and their daughters. These scales deposit in oil surface equipment such as separator tanks, tubular, and storage tanks. In this work, naturally occurring radionuclides and radiation exposure levels in some Syrian oil lines have been determined. Radiation measurements have shown high radiation exposure in some production sites and reached about 23 {mu}Sv/hr (production wellhead) which is higher than the normal background (0.09 - 012 {mu}Sv/hr). The highest value of the exposure around storage tanks was about o.5 {mu}Sv/hr. Moreover, the highest concentration of radionuclides in scales were found to be 47000 Bq/Kg and 55000 Bq/Kg for Ra-226 and Ra-228 respectively while in sludge samples, the Ra-226 concentration was about 24.2 Bq/Kg, a relatively very low activity. In addition, results have shown that soil contamination can occur by disposal of produced water to the surrounding environment. Furthermore, the present paper shows some of protection procedures, which should be followed by workers for radiation protection. (author). 10 refs., 4 tabs.

Helminth associations in white-toothed shrews Crocidura russula (Insectivora: Soricidae) from the Albufera Natural Park, Spain.

Science.gov (United States)

Portolés, Enrique; Granel, Pedro; Esteban, J Guillermo; Cabaret, Jacques

2004-06-01

The helminths of 218 white-toothed shrews from 29 sites in 2 biotopes in the Albufera Natural Park (Valencia, Spain) were examined from July 1990 to August 1991. An association analysis of helminths occurring at a prevalence of more than 4% was carried out for 4 species of cestodes located in the intestine (Hymenolepis pistillum, H. scalaris, H. tiara, and Pseudhymenolepis redonica) and 3 species of nematodes (Pseudophysaloptera sp. located in the stomach, Stammerinema rhopocephala larvae in the intestine and abdominal cavity, and Porrocaecum sp. in the thoracic and abdominal cavities). Bivariate (species pairs) versus multivariate analyses (associations within the entire set of species) were performed of presence-absence and of quantitative records (influence of intensity on associations). The associations were evaluated with respect to the sex and age of the host and to the sampling date and sites. The host and environment played a limited role, and the major determinant of species assemblage was phylogenetic. Positive associations were found among both the cestodes and the nematodes, whereas negative associations were found between cestodes and nematodes. The type of life cycle was probably the second greatest determinant of species associations. Nematodes using shrews as a paratenic host or as their definitive host were both positively associated.

Activity, specificity, and titer of naturally occurring canine anti-DEA 7 antibodies.

Science.gov (United States)

Spada, Eva; Proverbio, Daniela; Baggiani, Luciana; Canzi, Ilaria; Perego, Roberta

2016-11-01

The reported prevalence of naturally occurring anti-dog erythrocyte antigen (DEA) 7 antibodies in DEA 7-negative dogs is as high as 50%. Characterization of these antibodies may better define their importance in canine transfusion medicine. We determined in vitro activity, specificity, and titer of anti-DEA 7 antibodies in DEA 7-negative dogs. Plasma samples from 317 DEA 7-negative dogs were cross-matched with DEA 7-positive red blood cells (RBCs) using gel column technology. Agglutination occurred with DEA 7-positive RBCs but not with DEA 7-negative RBCs in 73 samples (23%), which were hence classified as containing anti-DEA 7 antibodies. These samples were evaluated for hemolytic and agglutinating activity, strength of agglutination, and antibody specificity and titers. All samples showed agglutination but none showed hemolysis. Gel agglutination was graded as 1+ for 20 samples (27%), 2+ for 49 samples (67%), 3+ for 4 samples (6%); no samples were graded 4+. The agglutination titer was DEA 7 antibodies were found in 23% of DEA 7-negative dogs. The presence of naturally occurring anti-DEA 7 antibodies suggests that cross-matching of canine blood recipients is advisable, even at first transfusion, to minimize delayed transfusion reactions. © 2016 The Author(s).

PLANT-PARASITIC NEMATODES ON STONE FRUITS AND CITRUS IN LEBANON

Directory of Open Access Journals (Sweden)

Said K. Ibrahim

2016-06-01

Full Text Available Ibrahim Said K., Ibrahim Azar, Christian Naser, Badran Akikki and Ludmilla Ibrahim. 2016. Plant-parasitic nematodes on stone fruits and citrus in Lebanon. Lebanese Science Journal, 17(1: 9-24. This study aimed to determine the occurrence, distribution of plant parasitic nematodes on stone fruits in Lebanon and to determine the effect of plant extracts on the mortality of several nematode species. A total of 308 soil samples were collected from five different crops. Almost all surveyed areas showed infection with nematodes. The soil infestation rate with nematodes in collected soil samples from all 10 surveyed crops ranged from 66.6 to 100%. Eighteen out of 308 soil samples were free of nematodes (5.8%. All the collected soil samples from nectarine and plum orchards were infested with nematodes (100%, followed by citrus (97.6%, apple (88.7%, pear and quince (85.7%, and cherry (81.4%. The lowest infection (66.6% was detected on almond and apricot. The level of infestation varied from one area to another and ranged between 0.1 and 28 nematodes per 1 g of soil, with the highest number obtained on cherry. Several genera were identified based on morphological characters including: root-knot nematodes (Meloidogyne spp., Tylenchulus, Xiphinema, Rotylenchus, Pratylenchus, and Longidorus. Tylenchulus and Radopholus spp. were the most common on citrus trees, whereas Pratylechus and Meloidogyne spp. were detected almost in all the samples collected from all the crops. Six chopped aromatic plants were tested in pot experiments to control nematodes population densities. The results revealed that carbofuran (nematicide was the most effective (88.48% in comparison to the plant materials. Allium sativum gave the highest control (76.52% followed by Tageta patula (72.0%, Cucurbita maxima (71.84% and Inula viscosa (63.96%. Origanum syriacum (55.04% and Thymus (53.72% were less effective in comparison to the rest of tested plant materials.

[Screening endophytic bacteria against plant-parasitic nematodes].

Science.gov (United States)

Peng, Shuang; Yan, Shuzhen; Chen, Shuanglin

2011-03-01

Plant-parasite nematode is one of the most important pathogens in plant. Our objective is to screen endophytic bacteria against plant-parasitic nematodes from plant. Endophytic bacteria were isolated and screened by testing their metabolite against Bursaphelenchus xylophilus in vitro. Those strains inhibiting B. xylophilus were selected to culture in liquid medium and fermentation conditions were optimized by orthogonal test. The stability of the antinematode substances was evaluated by various. In addition, four strains were identified by 16SrDNA sequence analysis. In total 13 strains of endophytic bacteria secreting antinematode metabolite were isolated from 6 species of plant. The supernatant of the fermentation broth of these endophytic bacteria gave 100% mortality of nematodes after treated as the follows: 1 ml each was mixed with 0.2 ml of the suspension of nematodes (2000 nematodes/ml) then incubated at 250C for 24 h, some of which could led to leakage or dissolution of nematodes. Among them, four strains, BCM2, SZ5, CCM7 and DP1, showed stronger activity than others. The supernatants diluted three times also gave not less than 95% mortality after 24 h treatment, and those from DP1 and SZ5 even gave 100% mortality. The fermentation conditions of the four strains were optimized and the antinematode activity grew up four times after optimization. The antinematode substances of these strains were found stable when treated with protease or heating or stored at 4 degrees C after 100 days, while instable when treated with acid or alkali. DP1 and CCM7 were identified to be Bacillus subtilis, while SZ5 and BCM2 to be Bacillus cereus. Endophytic bacteria secreting antinematode metabolite were found in economic crops. The metabolite of some strains showed strong and stable antinematode activity. Our results indicate the real potential of biocontrol by endophytic bacteria.

Individual and collective dose rates from naturally-occurring radionuclides in seafood

International Nuclear Information System (INIS)

Pentreath, R.J.; Camplin, W.C.; Allington, D.J.

1989-01-01

Although seafoods are not a large item in the UK diet, they are of interest because of the above-average quantities of naturally-occurring radionuclides which they contain -particularly shellfish. The single most important contributor is 210 Po; studies have therefore been made to examine the contribution which this nuclide makes to the dose received, both collectively and to individual high-rate consumers of shellfish. (author)

PLANT-PARASITIC NEMATODES ON STONE FRUITS AND CITRUS IN LEBANON

International Nuclear Information System (INIS)

Ibrahim, S.K.; Azar, I.; Naser, CH.; Akikki, B; Ibrahim, L.

2016-01-01

This study aimed to determine the occurrence, distribution of plant parasitic nematodes on stone fruits in Lebanon and to determine the effect of plant extracts on the mortality of several nematode species. A total of 308 soil samples were collected from five different crops. Almost all surveyed areas showed infection with nematodes.The soil infestation rate with nematodes in collected soil samples from all 10 surveyed crops ranged from 66.6 to 100%. Eighteen out of 308 soil samples were free of nematodes (5.8%). All the collected soil samples from nectarine and plum orchards were infested with nematodes (100%), followed by citrus (97.6%), apple (88.7%), pear and quince (85.7%), and cherry (81.4%). The lowest infection (66.6%) was detected on almond and apricot. The level of infestation varied from one area to another and ranged between 0.1and 28 nematodes per 1 g of soil, with the highest number obtained on cherry. Several genera were identified based on morphological characters including:root-knot nematodes (Meloidogynespp.), Tylenchulus, Xiphinema, Rotylenchus, Pratylenchus, and Longidorus. Tylenchulus and Radopholus spp. were the most common on citrus trees, whereas Pratylechus and Meloidogyne spp. were detected almost in all the samples collected from all the crops. Six chopped aromatic plants were tested in pot experiments to control nematodes population densities. The results revealed that carbofuran (nematicide) was the most effective (88.48%) in comparison to the plant materials. Allium sativum gave the highest control (76.52%) followed by Tageta patula (72.0%), Cucurbita maxima (71.84%) and Inula viscosa (63.96%). Origanum syriacum (55.04%)d Thymus (53.72%) were less effective in comparison to the rest of tested plant materials. (author)

Management of Root Knot Nematode on Tomato through Grafting Root Stock of Solanum sisymbriifolium

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Suraj Baidya

2017-05-01

Full Text Available The root-knot nematodes (Meloidogyne spp are difficult to manage once established in the field because of their wide host range, and soil-borne nature. Thus, the aim of the present study was to examine the use of resistant root stock of wild brinjal (Solanum sisymbriifolium to reduce the loss caused by the nematodes on tomato. For the management of root-knot nematodes, grafted plant with resistant root stock of the wild brinjal was tested under farmers’ field conditions at Hemza of Kaski district. Grafted and non-grafted plants were produced in root-knot nematode-free soil. Around three week-old grafted and non-grafted tomato plants were transplanted in four different plastic tunnels where root-knot nematodes had been reported previously. The plants were planted in diagonal position to each other as a pair plot in 80 × 60 cm2 spacing in an average of 20 × 7 m2 plastic tunnels. Galling Index (GI was recorded three times in five randomly selected plants in each plot at 60 days intervals. The first observation was recorded two months after transplanting. Total fruit yield was recorded from same plants. In the grafted plants, the root system was totally free from gall whereas in an average of 7.5 GI in 0-10 scale was recorded in the non-grafted plants. Fruits were harvested from time to time and cumulated after final harvest to calculate the total fruit yield. It was estimated that on an average tomato fruit yield was significantly (P>0.05 increased by 37 percent in the grafted plants compared with the non-grafted plants. Grafting technology could be used effectively for cultivation of commonly grown varieties, which are susceptible to root-knot nematodes in disease prone areas. This can be used as an alternative technology for reducing the use of hazardous pesticides for enhancing commercial organic tomato production.

Trait-mediated diversification in nematode predator–prey systems

NARCIS (Netherlands)

Mulder, C.; Helder, J.; Vervoort, M.T.W.; Vonk, J.A.

2011-01-01

Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding

Book review: Systematics of Cyst Nematodes (Nematoda: Heteroderinae)

Science.gov (United States)

The cyst nematodes are an important group of plant-parasitic nematodes that cause billions of dollars in economic damage to crops every year. This article reviews a recently published, two-volume monograph that describes the morphological and molecular characteristics of these agriculturally signif...

Nematode effector proteins: an emerging paradigm of parasitism

Science.gov (United States)

Phytonematodes use a stylet and secreted effectors to invade host tissues and extract nutrients to support their growth and development. The molecular function of nematode effectors is currently the subject of intense investigation. In this review, we summarize our current understanding of nematode ...

Infection Assay of Cyst Nematodes on Arabidopsis Roots.

Science.gov (United States)

Bohlmann, Holger; Wieczorek, Krzysztof

2015-09-20

Plant parasitic nematodes are devastating pests on many crops. Juveniles (J2) of cyst nematodes invade the roots to induce a syncytium. This feeding site is their only source of nutrients. Male nematodes leave the roots after the fourth molt to mate with females. The females stay attached to their syncytia throughout their life and produce hundreds of eggs, which are contained in their bodies. When the females die their bodies form the cysts, which protect the eggs. Cysts can survive for many years in the soil until favorable conditions induce hatching of the juveniles. The beet cyst nematode Heterodera schachtii ( H. schachtii )is a pathogen of sugar beet ( Beta vulgaris ) but can also complete its life cycle on Arabidopsis roots growing on agar plates under sterile conditions. We present here protocols for a stock culture of H. schachtii and an infection assay on agar plates.

Ijuhya vitellina sp. nov., a novel source for chaetoglobosin A, is a destructive parasite of the cereal cyst nematode Heterodera filipjevi.

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Samad Ashrafi

Full Text Available Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae, encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal

Ijuhya vitellina sp. nov., a novel source for chaetoglobosin A, is a destructive parasite of the cereal cyst nematode Heterodera filipjevi.

Science.gov (United States)

Ashrafi, Samad; Helaly, Soleiman; Schroers, Hans-Josef; Stadler, Marc; Richert-Poeggeler, Katja R; Dababat, Abdelfattah A; Maier, Wolfgang

2017-01-01

Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae), encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal and nematode

Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground.

Directory of Open Access Journals (Sweden)

Camila Cramer Filgueiras

Full Text Available Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes.

Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

Science.gov (United States)

Filgueiras, Camila Cramer; Willett, Denis S.; Junior, Alcides Moino; Pareja, Martin; Borai, Fahiem El; Dickson, Donald W.; Stelinski, Lukasz L.; Duncan, Larry W.

2016-01-01

Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes. PMID:27136916

Susceptibility of irradiated Galleria mellonella F1Larvae to Entomopathogenic Nematodes

International Nuclear Information System (INIS)

Salem, H.M.; Rizk, S.A.; Sayed, R.M.; Hussein, M.A; Hafez, S.E

2008-01-01

Combined effect of substerilizing doses of gamma radiation (40 and 100 Gy) and different concentrations of entomopathogenic nematodes (20, 40, 60, and 80 IJs) on the greater wax moth, Galleria mellonella was studied. The 4th larval instar resulted from irradiated male parent pupae mated with normal female were tested for susceptibility to Heterorhabditis bacteriophora BA1 and Steinernema carpocapsae BA2. The mortality rate of the larvae increased by increrasing radiation dose and nematode concentrations. The reproduction of both nematode strains decreased significantly with increasing the treatments (radiation dose and nematode concentrations). In addition, exposure to gamma radiation and entomopathogenic nematodes significantly decreased the total haemocyte count (THC) of the larvae with increasing radiation doses (40 and 100 Gy) and both nematode strains concentrations (20 and 40 IJs) and reached the minimal count at the combiend effect. Finally, larvae were more susceptible to Steinernema carpocapsa than Heterorhabditis bacteriophora. (author)

Remote Sensing of Parasitic Nematodes in Plants

Science.gov (United States)

Lawrence, Gary W.; King, Roger; Kelley, Amber T.; Vickery, John

2007-01-01

A method and apparatus for remote sensing of parasitic nematodes in plants, now undergoing development, is based on measurement of visible and infrared spectral reflectances of fields where the plants are growing. Initial development efforts have been concentrated on detecting reniform nematodes (Rotylenchulus reniformis) in cotton plants, because of the economic importance of cotton crops. The apparatus includes a hand-held spectroradiometer. The readings taken by the radiometer are processed to extract spectral reflectances at sixteen wavelengths between 451 and 949 nm that, taken together, have been found to be indicative of the presence of Rotylenchulus reniformis. The intensities of the spectral reflectances are used to estimate the population density of the nematodes in an area from which readings were taken.

First report of the spiral nematode Helicotylenchus microlobus infecting soybean in North Dakota

Science.gov (United States)

Spiral nematodes (Helicotylenchus spp.) are common plant-parasitic nematodes in fields of many crops. In June 2015, two soil samples were collected from a soybean field in Richland County, ND. Nematodes were extracted from soil using the sugar centrifugal flotation method. Plant-parasitic nematodes ...

Mapping genetic factors controlling potato - cyst nematode interactions

NARCIS (Netherlands)

Rouppe van der Voort, J.N.A.M.

1998-01-01

The thesis describes strategies for genetic mapping of the genomes of the potato cyst nematode and potato. Mapping in cyst nematodes was achieved by AFLP genotyping of single cysts and subsequent segregation analysis in a family of sibling populations. The genetic map of Globodera