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Sample records for feeding regime photoperiod

  1. Growth of juvenile Atlantic cod Gadus morhua in land-based recirculation systems: Effects of feeding regime, photoperiod and diet

    DEFF Research Database (Denmark)

    Fülberth, Michael; Moran, Damian; Jarlbæk, Henrik;

    2009-01-01

    . Three RAS units were used to simultaneously test three feed/photoperiod regimes that might be encountered in the wild or aquaculture; LightDark (LD) 24:0, LD12:11 (+ 1 h crepuscular periods) and LD6:6 (+ 12 h crepuscular periods). Feed was administered during the light period every 30 min for a 3 min...... feeding duration. In each RAS unit three diets (A, B and C) were tested, which were broadly similar in composition but from different manufacturers. Water exchange rate averaged 10–19% in the three recirculation systems, and key water quality parameters such as NH4+ and CO2 remained at low effect...

  2. Effect of different photoperiods on growth, feed utilization and ...

    African Journals Online (AJOL)

    Effect of different photoperiods on growth, feed utilization and survival of ... in body weight, relative growth rate (RGR), specific growth rate (SGR) and gross food ... of continuous darkness or low light intensity for optimal growth performance, ...

  3. Photoperiodic regime influences onset of lens opacities in a non-human primate

    Directory of Open Access Journals (Sweden)

    Marko Dubicanac

    2017-05-01

    Full Text Available Background Opacities of the lens are typical age-related phenomena which have a high influence on photoreception and consequently circadian rhythm. In mouse lemurs, a small bodied non-human primate, a high incidence (more than 50% when >seven years of cataracts has been previously described during aging. Previous studies showed that photoperiodically induced accelerated annual rhythms alter some of mouse lemurs’ life history traits. Whether a modification of photoperiod also affects the onset of age dependent lens opacities has not been investigated so far. The aim of this study was therefore to characterise the type of opacity and the mouse lemurs’ age at its onset in two colonies with different photoperiodic regimen. Methods Two of the largest mouse lemur colonies in Europe were investigated: Colony 1 having a natural annual photoperiodic regime and Colony 2 with an induced accelerated annual cycle. A slit-lamp was used to determine opacities in the lens. Furthermore, a subset of all animals which showed no opacities in the lens nucleus in the first examination but developed first changes in the following examination were further examined to estimate the age at onset of opacities. In total, 387 animals were examined and 57 represented the subset for age at onset estimation. Results The first and most commonly observable opacity in the lens was nuclear sclerosis. Mouse lemurs from Colony 1 showed a delayed onset of nuclear sclerosis compared to mouse lemurs from Colony 2 (4.35 ± 1.50 years vs. 2.75 ± 0.99 years. For colony 1, the chronological age was equivalent to the number of seasonal cycles experienced by the mouse lemurs. For colony 2, in which seasonal cycles were accelerated by a factor of 1.5, mouse lemurs had experienced 4.13 ± 1.50 seasonal cycles in 2.75 ± 0.99 chronological years. Discussion Our study showed clear differences in age at the onset of nuclear sclerosis formation between lemurs kept under different

  4. The effect of photoperiod on life history and blood-feeding activity in Aedes albopictus and Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Costanzo, K S; Schelble, S; Jerz, K; Keenan, M

    2015-06-01

    Several studies have examined how climatic variables such as temperature and precipitation may affect life history traits in mosquitoes that are important to disease transmission. Despite its importance as a seasonal cue in nature, studies investigating the influence of photoperiod on such traits are relatively few. This study aims to investigate how photoperiod alters life history traits, survival, and blood-feeding activity in Aedes albopictus (Skuse) and Aedes aegypti (Linnaeus). We performed three experiments that tested the effects of day length on female survival, development time, adult size, fecundity, adult life span, and propensity to blood feed in Ae. albopictus and Ae. aegypti. Each experiment had three photoperiod treatments: 1) short-day (10L:14D), 2) control (12L:12D), and 3) long-day (14L:10D). Aedes albopictus adult females were consistently larger in size when reared in short-day conditions. Aedes aegypti adult females from short-day treatments lived longer and were more likely to take a blood meal compared to other treatments. We discuss how species-specific responses may reflect alternative strategies evolved to increase survival during unfavorable conditions. We review the potential impacts of these responses on seasonal transmission patterns, such as potentially increasing vectorial capacity of Ae. aegypti during periods of shorter day lengths.

  5. Exposure to short photoperiod regime reduces ventral subicular lesion-induced anxiety-like behavior in Wistar rats.

    Science.gov (United States)

    Subhadeep, Duttagupta; Srikumar, B N; Shankaranarayana Rao, B S; Kutty, Bindu M

    2017-03-01

    Neurodegeneration of hippocampal structures is implicated in Alzheimer's disease (AD). Patients with AD exhibit 'sundown syndrome' featuring mood swings and anxiety. Although there are studies demonstrating circadian rhythm disruption associated with sundown phenomenon, the mechanisms underlying the emotional disturbances remain elusive. In the present study, we examined the relationship between subiculum (a key hippocampal output structure) and anxiety. Our study demonstrates that bilateral ventral subicular lesion (VSL) leads to anxiogenic behavior. In the elevated plus maze test, VSL rats made less number of entries into the open arms and spent significantly more time in the closed arms. Similarly, in the light-dark exploration test, VSL rats spent significantly more time in the dark chamber and made fewer entries into the light chamber. VSL also produced significant neurodegeneration in the paraventricular, suprachiasmatic and dorsomedial nuclei of the hypothalamus. Exposing VSL rats to a short photoperiod regime (SPR; 06/18h light-dark cycle) for 21days ameliorated the anxiety-like behavior. VSL rats on SPR also exhibited increased food consumption and higher core body temperature. Our study supports the hypothesis that the ventral subiculum regulates anxiety-like behavior and that SPR helps in the alleviation of such behavior. Even though the mechanisms underlying anxiolytic effects of light-dark cycle manipulation are yet to be elucidated, such non-pharmacological strategies can help to mitigate anxiety-like behavior. A proper understanding of the effectiveness of photoperiod manipulation will help in developing strategies in the management of emotional disturbances associated with affective and neurodegenerative disorders including AD. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Effects of photoperiod regimes and ultraviolet-C radiations on biosynthesis of industrially important lignans and neolignans in cell cultures of Linum usitatissimum L. (Flax).

    Science.gov (United States)

    Anjum, Sumaira; Abbasi, Bilal Haider; Doussot, Joël; Favre-Réguillon, Alain; Hano, Christophe

    2017-02-01

    Lignans and neolignans are principal bioactive components of Linum usitatissimum L. (Flax), having multiple pharmacological activities. In present study, we are reporting an authoritative abiotic elicitation strategy of photoperiod regimes along with UV-C radiations. Cell cultures were grown in different photoperiod regimes (24h-dark, 24h-light and 16L/8D h photoperiod) either alone or in combination with various doses (1.8-10.8kJ/m(2)) of ultraviolet-C (UV-C) radiations. Secoisolariciresinol diglucoside (SDG), lariciresinol diglucoside (LDG), dehydrodiconiferyl alcohol glucoside (DCG), and guaiacylglycerol-β-coniferyl alcohol ether glucoside (GGCG) were quantified by using reverse phase-high performance liquid chromatography (RP-HPLC). Results showed that the cultures exposed to UV-C radiations, accumulated higher levels of lignans, neolignans and other biochemical markers than cultures grown under different photoperiod regimes. 3.6kJ/m(2) dose of UV-C radiations resulted in 1.86-fold (7.1mg/g DW) increase in accumulation of SDG, 2.25-fold (21.6mg/g DW) in LDG, and 1.33-fold (9.2mg/g DW) in GGCG in cell cultures grown under UV+photoperiod than their respective controls. Furthermore, cell cultures grown under UV+dark showed 1.36-fold (60.0mg/g DW) increase in accumulation of DCG in response to 1.8kJ/m(2) dose of UV-C radiations. Smilar trends were observed in productivity of SDG, LDG and GGCG. Additionally, 3.6kJ/m(2) dose of UV-C radiations also resulted in 2.82-fold (195.65mg/l) increase in total phenolic production, 2.94-fold (98.9mg/l) in total flavonoid production and 1.04-fold (95%) in antioxidant activity of cell cultures grown under UV+photoperiod. These findings open new dimensions for feasible production of biologically active lignans and neolignans by Flax cell cultures.

  7. Female feeding regime and polyandry in the nuptially feeding nursery web spider, Pisaura mirabilis

    Science.gov (United States)

    Prokop, Pavol; Maxwell, Michael R.

    2009-02-01

    We examined the influence of female feeding regime on polyandry in the nuptially feeding nursery web spider (Pisaura mirabilis). In this species, the nuptial gift, a dead prey item wrapped in the male’s silk, is physically separate from the ejaculate. We manipulated female feeding regime (starved or fed) and the presence or absence of a gift with three successive males to test direct-benefits hypotheses (nuptial gift or sperm supply) for the expression of polyandry. The presence of a gift was necessary for copulation, as no male without a gift successfully copulated. Female mating behavior most strongly supports polyandry due to the accumulation of gifted food items (“nuptial gift” direct-benefits hypothesis). Starved females that were presented with a gift accepted significantly more gifts and inseminations than fed females. Most starved females (74%) copulated two or more times, as opposed to only 3% of the fed females. Nearly all of the females that accepted a gift subsequently copulated. The nuptial gift item seems to function as male mating effort and females appear to receive multiple matings as part of a feeding strategy.

  8. Feed and feeding regime affect growth rate and gonadosomatic index of adult zebrafish (Danio rerio).

    Science.gov (United States)

    Gonzales, John M; Law, Sheran Hiu Wan

    2013-12-01

    A 5-week study was conducted to evaluate commercially available Artemia, Ziegler zebrafish diet, and Calamac diet fed in five different feeding regimes on the growth and reproductive development of 7-month-old zebrafish. Zebrafish were fed to satiation three times daily during the normal work week and twice daily during the weekend and holidays. Zebrafish in dietary groups CCC (Calamac three times daily) and CCA (Calamac twice daily, Artemia once daily) had a significantly (pzebrafish in dietary group 5 had significantly larger gonadosomatic index (GSI) values than all other groups, while female zebrafish in dietary group CCC had significantly larger GSI values than all other groups. No differences in the fatty acid content of female gonads were detected. Zebrafish fed solely Artemia had the greatest weight loss and lowest GSI values. Preliminary evidence of protein sparing in zebrafish is reported. Collectively, this study sheds more light into the effects of the use of commercially available feeds and feeding regime on the rearing of zebrafish.

  9. Regulation of feeding behavior in adult Drosophila melanogaster varies with feeding regime and nutritional state.

    Science.gov (United States)

    Edgecomb, R S; Harth, C E; Schneiderman, A M

    1994-12-01

    The regulation of feeding behavior in adult Drosophila melanogaster includes such elements as ingestion responsiveness, volume ingested in a single meal, food storage in the crop and rate of defecation. Our results suggest that feeding behavior varies in a manner dependent on feeding regime (food-deprived or ad-libitum-fed) and nutritional state. Fed flies that are subsequently food-deprived become increasingly more responsive to food stimuli over time and, when offered 1% agar diets containing different concentrations of sucrose, ingest greater amounts of diets that have higher sucrose concentrations. When fed ad libitum for 72 h on these same diets, D. melanogaster maintained much smaller crops on average than food-deprived flies fed a single meal. Additionally, ad-libitum-fed flies are grouped into two categories depending on the concentration of sucrose in the diet. Flies fed for 72 h on 1% agar diets having 50 mmoll-1 sucrose or more are not affected by the concentration of sucrose in the diet, while flies fed on diets of 15 or 25 mmoll-1 sucrose increase ingestion responsiveness, crop size and the rate of defecation with decreasing concentrations of sucrose in the diet. Flies fed on even lower sucrose concentrations (5 or 10 mmoll-1 sucrose) for 27-72 h exhibit both a shift over time to larger crop sizes and increased mortality over those of flies fed 15 mmoll-1 sucrose. These data suggest that flies fed ad libitum are capable of modulating their feeding behavior in response to their nutritional state.

  10. Recommended feeding regime and light climate in live feed cultures of the calanoid copepod Acartia tonsa Dana

    DEFF Research Database (Denmark)

    Jepsen, Per Meyer; Steensbjerg Bjørbæk, Niels; Rayner, Thomas Allan

    2017-01-01

    Understanding and optimising the parameters that controls the success for copepod cultures are the foundation for large scaled copepod cultures. Many underlying copepod culture parameters are already quantified and comprehended, but there is a lack in knowledge of optimising feeding regimes for c...

  11. Optimization of Stocking Density for the Sea Cucumber,Apostichopus japonicus Selenka, Under Feed-Supplement and Non-Feed-Supplement Regimes in Pond Culture

    Institute of Scientific and Technical Information of China (English)

    QIN Chuanxin; DONG Shuanglin; TAN Fuyi; TIAN Xiangli; WANG Fang; DONG Yunwei; GAO Qinfeng

    2009-01-01

    Optimal stocking densities were investigated for the sea cucumber Apostichopus japonicus Selenka under feed-supplement and non-feed-supplement regimes in net enclosures for 333 d. Substantial weight loss occurred during the aestivation phase (AE).Decreased growth rates were also observed during the winter phase (WT). In contrast, sea cucumbers showed rapid growth during the spring (SP) and autumn (AU) phases. Feeding regimes considerably influenced the growth performance, i.e., sea cucumbers grew faster under feed-supplement regime than under non-feed-supplement regime (P< 0.05). The average survival rates of sea cucumbers under feed-supplement regime were higher than those under non-feed-supplement regime for both the autumn phase and spring phase,but the differences were only significant for the latter phase (P<0.05). The fitted B-N curves showed that the optimal stocking densities, in terms of net production, were 22.3 ind. m-2 for feed-supplement regime and 14.1 ind. m-2 for non-feed-supplement regime.

  12. A two-diet feeding regime for lactating sows reduced nutrient deficiency in early lactation and improved milk yield

    DEFF Research Database (Denmark)

    Pedersen, Trine Friis; Sønderby Bruun, Thomas; Feyera, Takele

    2016-01-01

    to their individual requirements for maintenance and milk production. Thus, a basal diet was formulated and supplied to meet the energy requirement for maintenance and a lactation supplement was formulated to meet the dynamic requirement of nutrients for milk production. Sows and piglets were weighed and feed intake......The objective of the present study was to evaluate whether a new feeding concept composed of two dietary components fed daily throughout lactation could minimize sow weight loss and increase milk yield (MY) and piglet weight gain. In total, 14 sows were included in the experiment from parturition...... until weaning 28 d later. The sows were fed one of two dietary feeding regimes from lactation d 2 and throughout lactation. The 1-diet feeding regime represented the Danish feeding standards and recommendations. The new 2-diet regime supplied sows feed and nutrients (ME and AA) according...

  13. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways.

    Science.gov (United States)

    Mulat, Daniel Girma; Jacobi, H Fabian; Feilberg, Anders; Adamsen, Anders Peter S; Richnow, Hans-Hermann; Nikolausz, Marcell

    2015-10-23

    Flexible biogas production that adapts biogas output to energy demand can be regulated by changing feeding regimes. In this study, the effect of changes in feeding intervals on process performance, microbial community structure, and the methanogenesis pathway was investigated. Three different feeding regimes (once daily, every second day, and every 2 h) at the same organic loading rate were studied in continuously stirred tank reactors treating distiller's dried grains with solubles. A larger amount of biogas was produced after feeding in the reactors fed less frequently (once per day and every second day), whereas the amount remained constant in the reactor fed more frequently (every 2 h), indicating the suitability of the former for the flexible production of biogas. Compared to the conventional more frequent feeding regimes, a methane yield that was up to 14% higher and an improved stability of the process against organic overloading were achieved by employing less frequent feeding regimes. The community structures of bacteria and methanogenic archaea were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA and mcrA genes, respectively. The results showed that the composition of the bacterial community varied under the different feeding regimes, and the observed T-RFLP patterns were best explained by the differences in the total ammonia nitrogen concentrations, H2 levels, and pH values. However, the methanogenic community remained stable under all feeding regimes, with the dominance of the Methanosarcina genus followed by that of the Methanobacterium genus. Stable isotope analysis showed that the average amount of methane produced during each feeding event by acetoclastic and hydrogenotrophic methanogenesis was not influenced by the three different feeding regimes.

  14. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways

    Science.gov (United States)

    Mulat, Daniel Girma; Jacobi, H. Fabian; Feilberg, Anders; Adamsen, Anders Peter S.; Richnow, Hans-Hermann

    2015-01-01

    Flexible biogas production that adapts biogas output to energy demand can be regulated by changing feeding regimes. In this study, the effect of changes in feeding intervals on process performance, microbial community structure, and the methanogenesis pathway was investigated. Three different feeding regimes (once daily, every second day, and every 2 h) at the same organic loading rate were studied in continuously stirred tank reactors treating distiller's dried grains with solubles. A larger amount of biogas was produced after feeding in the reactors fed less frequently (once per day and every second day), whereas the amount remained constant in the reactor fed more frequently (every 2 h), indicating the suitability of the former for the flexible production of biogas. Compared to the conventional more frequent feeding regimes, a methane yield that was up to 14% higher and an improved stability of the process against organic overloading were achieved by employing less frequent feeding regimes. The community structures of bacteria and methanogenic archaea were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA and mcrA genes, respectively. The results showed that the composition of the bacterial community varied under the different feeding regimes, and the observed T-RFLP patterns were best explained by the differences in the total ammonia nitrogen concentrations, H2 levels, and pH values. However, the methanogenic community remained stable under all feeding regimes, with the dominance of the Methanosarcina genus followed by that of the Methanobacterium genus. Stable isotope analysis showed that the average amount of methane produced during each feeding event by acetoclastic and hydrogenotrophic methanogenesis was not influenced by the three different feeding regimes. PMID:26497462

  15. Estimation of metabolic heat production and methane emission in Sahiwal and Karan Fries heifers under different feeding regimes

    Directory of Open Access Journals (Sweden)

    Sunil Kumar

    2016-05-01

    Full Text Available Aim: The objective of this study was designed to estimate the metabolic heat production and methane emission in Sahiwal and Karan Fries (Holstein-Friesian X Tharparkar heifers under two different feeding regimes, i.e., feeding regime-1 as per the National Research Council (NRC (2001 and feeding regime-2 having 15% higher energy (supplementation of molasses than NRC (2001. Materials and Methods: Six (n = 6 healthy heifers of Sahiwal and Karan Fries with 18-24 months of age were selected from Indian Council of Agricultural Research-National Dairy Research Institute, Karnal. An initial 15 days was maintained under feeding regime-1 and feeding regime-2 as adaptation period; actual experiment was conducted from 16th day onward for next 15 days. At the end of feeding regimes (on day 15th and 16th, expired air and volume were collected in Douglas bag for two consecutive days (morning [6:00 am] and evening [4:00 pm]. The fraction of methane and expired air volume were measured by methane analyzer and wet test meter, respectively. The oxygen consumption and carbon dioxide production were measured by iWorx LabScribe2. Results: The heat production (kcal/day was significantly (p0.05. The energy loss as methane (% from total heat production was significantly (p<0.05 higher in feeding regime-1. The body weight (kg, metabolic body weight (W0.75, and basal metabolic rate (kcal/kg0.75 were significantly (p<0.05 higher in feeding regime-2 in both breeds. Conclusions: This study indicates that higher energy diet by supplementing molasses may reduce energy loss as methane and enhance the growth of Sahiwal and Karan Fries heifers.

  16. The influence of different dietary energy content and feeding regimes on growth and feed utilization of European sea bass (Dicentrarchus labrax, L.

    Directory of Open Access Journals (Sweden)

    Pier Paolo Gatta

    2010-01-01

    Full Text Available The growing importance of European sea bass (Dicentrarchus labrax in aquaculture underlines the need to optimize the feeding strategy for this fish species. The aim of the present study was to assess the effect of dietary energy content and feeding regime on growth performance, feed uti- lization and feeding costs for European sea bass. Seven hundreds and forthyfourfish(averageinitial forthyfourfish(averageinitial four fish ( average initial body weight 68g were randomly allocated into twelve tanks 800 l in a closed recirculation system (water temperature: 22°C; dissolved oxygen ≥90% of saturation. Three isoproteic (47% crude protein extruded diets were formulated with different lipid levels i.e. 16% (diet D16, 24% (diet D24 and 32% (diet D32 and each diet was fed at two different feeding regimes (satiation and 80% satiation accord- ing to a bifactorial experimental design. Feed intake (FI was recorded daily. After 77 days, fish were bulk weighed and growth, SGR and FCR were calculated. Feedingregimesaffectedall theanalysed Feeding regimes affected all the analysed parameters (P<0.05, whereas diet influenced only FCR, FI, protein and lipid intake and the economic efficiency ratio (EER. Fish fed the lowest energy content diet (D16 to satiation resulted in the highest feed intake, a FCR similar to that of fish fed diets D24 and D32 and in the lowest EER.

  17. Managing hytrosavirus infections in Glossina pallidipes colonies: feeding regime affects the prevalence of salivary gland hypertrophy syndrome.

    Directory of Open Access Journals (Sweden)

    Adly M M Abd-Alla

    Full Text Available Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH syndrome and the virus isolated from Glossina pallidipes (GpSGHV has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. Due to the deleterious impact of SGHV on G. pallidipes colonies, several approaches were investigated to develop a virus management strategy. Horizontal virus transmission is the major cause of the high prevalence of the GpSGHV in tsetse colonies. Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane, instead of the regular feeding regime (several successive feeds per membrane, was among the proposed approaches to reduce GpSGHV infections. However, due to the absence of disposable feeding equipment (feeding trays and silicone membranes, the implementation of a clean feeding approach remains economically difficult. We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources. The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9 virus copies in regular colonies to an average of 10(2.5 and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach. The clean feeding approach also reduced the virus load from an average of 10(8 virus copy numbers to an average of 10(3 virus copies and SGH prevalence of 10% to 4% in flies fed after the clean fed colony. Taken together, these data indicate that the clean feeding approach is applicable in large-scale G. pallidipes production facilities and eliminates the deleterious effects of the virus and the SGH syndrome in these colonies.

  18. Bodyweight and body condition score in rabbits on four different feeding regimes.

    Science.gov (United States)

    Prebble, J L; Shaw, D J; Meredith, A L

    2015-03-01

    The aim of this study was to assess the effects of four diet regimes (extruded diet with ad lib hay, muesli with ad lib hay, ad lib hay only, ad lib muesli only) on bodyweight and body condition score in rabbits. Thirty-two Dutch rabbits were studied over 9 months. Bodyweight and body condition score were recorded weekly. All groups gained weight with age, but relative to the ad lib hay only group (mean, 1 · 77 ± 0 · 13 kg), after 9 months rabbits in the ad lib muesli only group were 146% heavier (2 · 59 ± 0 · 32 kg); extruded diet with ad lib hay group 125% heavier (2 · 21 ± 0 · 10 kg); and muesli with ad lib hay group 123% heavier (2 · 18 ± 0 · 13 kg). Median body condition score of the ad lib muesli only group was obese (4 · 5) and was higher than that in both the extruded diet with ad lib hay and muesli with ad lib hay (median = 3 · 5) groups (P lib hay and muesli with ad lib hay groups had above-ideal body condition score despite having bodyweights within the breed standard range. The ad lib hay only group had a median body condition score of 3 (ideal). There was an overall positive correlation between body condition score and weight (qs = 0 · 814, P < 0 · 001). The feeding of muesli without hay should be avoided, to prevent obesity. © 2014 British Small Animal Veterinary Association.

  19. Behavioural responses under different feeding methods and light regimes of the African catfish (Clarias gariepinus) juveniles

    NARCIS (Netherlands)

    Almazán Rueda, P.; Schrama, J.W.; Verreth, J.A.J.

    2004-01-01

    Little is known about the behaviour of fish under culture conditions. Several factors may have a direct effect on fish behaviour and its variations during the day. This study assessed the effect of feeding method (continuous by self-feeders vs. twice a day hand-feeding), light intensity (15 vs. 150

  20. Effects of feeding regime and fattening season on performance and production efficiency of small-scale rabbit farms.

    Directory of Open Access Journals (Sweden)

    Alma Llambiri

    2010-08-01

    Full Text Available Five small scale family farms with rabbits of local breed were included in the study. Two groups of rabbits per farm were fattened during summer and winter seasons. One group was fed in usual way with feeds produced in farm consisted mainly of alfalfa dry or fresh depending on seson and family residues. The feeding of the other group was daily supplemented with 25 g concentrate feedstuffs(17% protein bought in the market. Supplementation with concentrate feedstuffs showed to improve meat production from rabbits in both seasons. Live weight at the end of fattening was increased with 210 g and 360 g respectively during winter and summer season. The factors that affect the differences in live weight realized were feeding regime, sex of rabbit (P<0.001 and season of fattening (P<0.01. Approaching growth curves with theoretical one of Gomperz showed that concentrate adding in feed ration improved daily weight gain. It did not affect the dynamics of body weight change. It affects the gradient of quantity of daily gains of rabbits. Concentrate supplementation of daily feeding during fattening period increased up to 15 % the meat production as well as net income of the farm.

  1. Oxidative and lipolytic changes during ripening of Iberian hams as affected by feeding regime: extensive feeding and alpha-tocopheryl acetate supplementation.

    Science.gov (United States)

    Cava, R; Ruiz, J; Ventanas, J; Antequera, T

    1999-06-01

    The effect of pig feeding in an extensive system based on acorn and pasture or in confinement with a control diet containing 5 mg α-tocopheryl acetate kg(-1) of feed and a 100 mg α-tocopheryl acetate kg(-1) enriched diet on evolution of lipid changes throughout ripening of dry-cured hams was investigated. Feeding regime significantly affected TBA-RS, peroxide value and hexanal content of Biceps femoris and Semimembranosus muscles. Muscles from pigs fed supplemented diet with α-tocopherol or fed extensively on acorn and grass showed significant lower (p<0.05) TBA-RS and peroxide value than ham muscles from pigs fed the basal diet at 210 days of processing. Both feedings reduced significantly (p<0.05) hexanal content at day 210 and day 700. Muscle slices from pigs fed on acorn showed significant higher scores (p<0.05) in aroma and flavour intensity, cured flavour and numerically lower rancid scores than those from control diet hams. ©

  2. Photoperiodism in Neurospora crassa

    NARCIS (Netherlands)

    Tan, Ying; Merrow, Martha; Roenneberg, Till

    2004-01-01

    Plants and animals use day or night length for seasonal control of reproduction and other biological functions. Overwhelming evidence suggests that this photoperiodic mechanism relies on a functional circadian system. Recent progress has defined how flowering time in plants is regulated by

  3. No evidence for a bioenergetic advantage from forced swimming in rainbow trout under a restrictive feeding regime

    DEFF Research Database (Denmark)

    Skov, Peter Vilhelm; Lund, Ivar; Margarido Pargana, Alexandre

    2015-01-01

    during a 15 week growth experiment, in which fish were reared at three different current speeds: 1 BL s(-1), 0.5 BL s(-1) and still water (approximate to 0 BL s(-1)). Randomly selected groups of 100 fish were distributed among twelve 600 L tanks and maintained on a restricted diet regime. Specific growth...... rate (SGR) and feed conversion ratio (FCR) were calculated from weight and length measurements every 3 weeks. Routine metabolic rate (RMR) was measured every hour as rate of oxygen consumption in the tanks, and was positively correlated with swimming speed. Total ammonia nitrogen (TAN) excretion rates...... and the current speed at which fish were reared, fish that were forced to swim and were fed restrictively consequentially had poorer growth and feed utilization. The results show that for rainbow trout, water current can negatively affect growth despite promoting minor positive changes in substrate utilization...

  4. Estimation of length-weight relationship and condition factor of spotted snakehead Channa punctata (Bloch) under different feeding regimes.

    Science.gov (United States)

    Datta, Surjya Narayan; Kaur, Vaneet Inder; Dhawan, Asha; Jassal, Geeta

    2013-01-01

    Comparative study was conducted to observe the efficacy of different feeding regimes on growth of Channa punctata. Six iso- proteinous diets were prepared by using different agro industrial by-products. Maximum weight gain was recorded with diet having 66.75% rice bran, 11.50% mustard cake, 23.0% groundnut cake, 5% molasses, 1.5% vitamin-mineral mixture and 0.5% salt with specific growth rate of 0.408. The experimental fish recorded the value of exponent 'b' in the range of 2.7675 to 4.3922. The condition factor 'K' of all experimental fish was above 1.0 (1.094- 1.235) indicating robustness or well being of experimented fish.

  5. Determination of optimum operating conditions for production of polyhydroxybutyrate by activated sludge submitted to dynamic feeding regime

    Institute of Scientific and Technical Information of China (English)

    QU Bo; LIU JunXin

    2009-01-01

    Polyhydroxybulyrate (PHB) was produced by activated sludge in a two-stage process. In the first stage, the sludge with high storage potential was enriched in a sequencing batch reactor (SBR) operated by a dynamic feeding regime. The biosynthesis of PHB was sequentially accomplished in a batch reactor in the second stage. This article focused on the optimization of PHB content by evaluating the effects of three critical factors: Dissolved oxygen, pH and food-to-microorganism (F/M) ratio in the batch reactor. The results showed that the rate of substrate uptake, as well as the yield and content of PHB increased with the increase of dissolved oxygen concentration. The control of pH was not necessary under the weak alkaline condition for improvement of PHB content, except for the case in which the pH value was out of rang of 1.0 to 10.0. The enhanced F/M ratio favored PHB accumulation in the range of 1.0 to 4.5 C-mmol/C-mmol and the highest PHB content, 64%, was achieved at 4.5 C-mmol/O-mmol. When F/M ratio was enhanced to 6.0 C-retool/C-retool, the phenomenon of utilizing simultaneously intracellular PHB and external substrate by sludge was observed, which resulted in a sharp decrease of PHB con-tent. The microscopic observation clearly confirmed that dynamic feeding regime was effective for selecting and enriching the sludge with a high storage potential.

  6. Involvement of cholecystokinin (CCK) in the daily pattern of gastrointestinal regulation of Senegalese sole (Solea senegalensis) larvae reared under different feeding regimes.

    Science.gov (United States)

    Navarro-Guillén, Carmen; Rønnestad, Ivar; Jordal, Ann-Elise Olderbakk; Moyano, Francisco Javier; Yúfera, Manuel

    2017-01-01

    Cholecystokinin (CCK) is an important regulator of pancreatic enzyme secretion in adult mammals and teleosteans. Although some studies have focused on the interaction between CCK and trypsin in marine fish larvae, little is known about the circadian patterns of the regulatory mechanism involving these two digestive components. In this study, we took advantage of the characteristic change from a diurnal to a nocturnal feeding habit that occurs in Senegalese sole (Solea senegalensis) post-larvae, to conduct an experiment where larvae and postlarvae were submitted to three different feeding regimes from mouth opening: continuous feeding, diurnal feeding and nocturnal feeding. The aim was to establish different daily feeding scenarios to uncover the operating mechanisms of CCK and tryptic enzyme activity over the 24-hourcycle to better understand the regulation of digestion in developing fish larvae. Results show a prevalence of simultaneous and opposing trends of CCK level and tryptic activity as a function of the postprandial time. This finding supports the existence of a regulatory loop between these two digestive components in pre- and post-metamorphic Senegal sole larvae. In addition, CCK level was also modulated by the gut content, tending to be lower when the gut is full and higher when is being emptied. Furthermore, larvae were able to synchronize digestive functions to very different feeding regimes, although it seems to be important having a diurnal feeding phase during pre-metamorphic stages for a proper development.

  7. PHOTOPERIODIC CONTROL OF ADULT DIAPAUSE IN CHRYSOPERLA SINICA (TJEDER) (NEUROPTERA: CHRYSOPIDAE) -I. CRITICAL PHOTOPERIOD AND SENSITIVE STAGES OF ADULT DIAPAUSE INDUCTION

    Institute of Scientific and Technical Information of China (English)

    Yong-yuXu; Ji-yuanMu; CuiHu; Hong-gangWang

    2004-01-01

    Photoperiodic sensitivity for diapause induction of the green lacewing, Chrysoperla sinica (Tjeder) was examined at 22℃. The adult diapause of C. sinica was induced by short-day photoperiods, and the critical photoperiod for its induction was between 12.5L-11.5D and 13L-11D.Adults developed without diapause under long-day conditions, and entered diapause under short-day conditions. The adult stage was the uppermost sensitive stage for adult diapause induction, adults could go into diapause only when the emerging adults were under diapause-inducing short-day photoperiods. The short-day photoperiodic experience by transferring between 15L: 9D and 9L: 15D at preimaginal stages did not result in adult diapause under 15L: 9D photo regime, although some treatments extended the pre-oviposition period in adult stage. The results showed that the 3rd instar larvae and pre-pupae were more sensitive to the photoperiodic change from 15L: 9D to 9L: 15D photo regime than the other preimaginal stages.

  8. Photoperiod in three xanthium populations from the tropic of cancer in Mexico.

    Science.gov (United States)

    McMillan, C

    1969-07-18

    Diverse photoperiodic responses were shown by three populations of Xanthium strumarium L. originating between 22 degrees and 25 degrees N on the western coast near Culiacán, Sinaloa; in the Chihuahuan Desert near Matehuala, San Luis Potoś; and on the Gulf Coast near Ciudad Mante, Tamaulipas, respectively. A combination of differences in critical night length and in ripeness-to-flower response (maturity) appears to be the basis for reproductive adaptation of these populations to different climatic regimes that prevail at the same latitude (and photoperiodic regime).

  9. Predicting Acorn-Grass Weight Gain Index using non-destructive Near Infrared Spectroscopy in order to classify Iberian pig carcasses according to feeding regime

    Directory of Open Access Journals (Sweden)

    Pérez-Marín, D.

    2013-04-01

    Full Text Available The classification of Iberian pig carcasses into different commercial categories according to feeding regime was evaluated by means of a non-destructive analysis of the subcutaneous adipose tissue using Near Infrared Spectroscopy (NIRS. A quantitative approach was used to predict the Acorn-Grass Weight Gain Index (AGWGI, and a set of criteria was established for commercial classification purposes. A total of 719 animals belonging to various batches, reflecting a wide range of feeding regimes, production systems and years, were analyzed with a view to developing and evaluating quantitative NIRS models. Results for the external validation of these models indicate that NIRS made clear differentiation of batches as a function of three feeding regimes possible with high accuracy (Acorn, Recebo and Feed, on the basis of the mean representative spectra of each batch. Moreover, individual analysis of the animals showed a broad consensus between field inspection information and the classification based on the AGWGI NIRS prediction, especially for extreme categories (Acorn and Feed.La clasificación en distintas categorías comerciales según régimen alimenticio de canales de cerdo Ibérico fue evaluada mediante el análisis no destructivo de muestras de tejido adiposo subcutáneo por Espectroscopía del Infrarrojo Cercano (NIRS. Partiendo de una aproximación cuantitativa para predecir el Índice de Reposición en Montanera (IRM se establecieron una serie de criterios para proceder a su clasificación comercial. Se analizaron un total de 719 animales pertenecientes a diversas partidas, que recogen una amplia variabilidad de muestras de distintos regímenes alimenticios, campañas y sistemas productivos, para el desarrollo y evaluación de los modelos NIRS cuantitativos. Los resultados de validación externa de los modelos indicaron que es posible discriminar con una gran exactitud entre partidas de distintos categorías (Bellota, Recebo y Cebo, en base

  10. Effect of artificial photoperiod on the blood cell indices of the catfish, Clarias batrachus

    Directory of Open Access Journals (Sweden)

    S Srivastava

    2010-04-01

    Full Text Available The present study is aimed to assess the influence of artificial photoperiod on the blood cell indices of an Indian catfish, Clarias batrachus(Linn.. Blood samples taken from adult fishes exposed to artificial photoperiod of 24L:0D and 0L:24D for a short period of 24 hrs, were analyzed for total RBC, total WBC, differential leukocyte count (DLC and some physiological variables – glucose and chloride. The total RBC and WBC counts were unaffected by both the artificial photoperiod regimes. However, lymphopenia (p<.05 and neutrophilia (p<.05 were observed under 24L:0D photoperiod. Blood chloride levels were significantly higher (p<.05 in 24L:0D whereas blood glucose levels remained unchanged in both the photoperiod treatments. The 0L:24D photoperiod did not produce any significant change in the blood cell indices neither in the physiological variables. The findings indicate that exposure to continuous light for as short a duration as of 24 hrs elicits stress responses in the leukocyte profile of this nocturnal fish and highlights the role of leukocyte profile as potential stress biomarkers in vertebrates.

  11. A photoperiod-responsive protein compendium and conceptual proteome roadmap outline in maize grown in growth chambers with controlled conditions.

    Science.gov (United States)

    Li, You-Zhi; Fan, Xian-Wei; Chen, Qiang; Zhong, Hao

    2017-01-01

    Maize (Zea mays L.) is one of the major staple food crops of the world. However, high photoperiod sensitivity, especially for tropical germplasms, impedes attempts to improve maize agronomical traits by integration of tropical and temperate maize germplasms. Physiological and phenotypic responses of maize to photoperiod have widely been investigated based on multi-site field observations; however, proteome-based responsive mechanisms under controlled photoperiod regimes, nutrient and moisture soils are not yet well understood. In the present study, we sequenced and analyzed six proteomes of tropically-adapted and photoperiod-sensitive M9 inbred line at the vegetative 3 stage and proteomes from tropically-adapted and photoperiod-sensitive Shuang M9 (SM9) inbred line at the vegetative-tasseling stage. All plants were grown in growth chambers with controlled soil and temperature and three photoperiod regimes, a short photoperiod (SP) of 10 h light/14 h dark, a control neutral photoperiod (NP) of 12 h light/12 h dark, and a long photoperiod (LP) of 16 h light/8 h dark for a daily cycle. We identified 4,395 proteins of which 401 and 425 differentially-expressed proteins (DPs) were found in abundance in M9 leaves and in SM9 leaves as per SP/LP vs. NP, respectively. Some DPs showed responses to both SP and LP while some only responded to either SP or LP, depending on M9 or SM9. Our study showed that the photoperiodic response pathway, circadian clock rhythm, and high light density/intensity crosstalk with each other, but apparently differ from dark signaling routes. Photoperiod response involves light-responsive or dark-responsive proteins or both. The DPs positioned on the signaling routes from photoperiod changes to RNA/DNA responses involve the mago nashi homolog and glycine-rich RNA-binding proteins. Moreover, the cell-to-cell movement of ZCN14 through plasmodesmata is likely blocked under a 16-h-light LP. Here, we propose a photoperiodic model based on our findings

  12. Food-anticipatory activity in Syrian hamsters: behavioral and molecular responses in the hypothalamus according to photoperiodic conditions.

    Science.gov (United States)

    Dantas-Ferreira, Rosana F; Dumont, Stéphanie; Gourmelen, Sylviane; Cipolla-Neto, José; Simonneaux, Valérie; Pévet, Paul; Challet, Etienne

    2015-01-01

    When food availability is restricted, animals adjust their behavior according to the timing of food access. Most rodents, such as rats and mice, and a wide number of other animals express before timed food access a bout of activity, defined as food-anticipatory activity (FAA). One notable exception amongst rodents is the Syrian hamster, a photoperiodic species that is not prone to express FAA. The present study was designed to understand the reasons for the low FAA in that species. First, we used both wheel-running activity and general cage activity to assess locomotor behavior. Second, the possible effects of photoperiod was tested by challenging hamsters with restricted feeding under long (LP) or short (SP) photoperiods. Third, because daytime light may inhibit voluntary activity, hamsters were also exposed to successive steps of full and skeleton photoperiods (two 1-h light pulses simulating dawn and dusk). When hamsters were exposed to skeleton photoperiods, not full photoperiod, they expressed FAA in the wheel independently of daylength, indicating that FAA in the wheel is masked by daytime light under full photoperiods. During FAA under skeleton photoperiods, c-Fos expression was increased in the arcuate nuclei independently of the photoperiod, but differentially increased in the ventromedial and dorsomedial hypothalamic nuclei according to the photoperiod. FAA in general activity was hardly modulated by daytime light, but was reduced under SP. Together, these findings show that food-restricted Syrian hamsters are not prone to display FAA under common laboratory conditions, because of the presence of light during daytime that suppresses FAA expression in the wheel.

  13. Food-anticipatory activity in Syrian hamsters: behavioral and molecular responses in the hypothalamus according to photoperiodic conditions.

    Directory of Open Access Journals (Sweden)

    Rosana F Dantas-Ferreira

    Full Text Available When food availability is restricted, animals adjust their behavior according to the timing of food access. Most rodents, such as rats and mice, and a wide number of other animals express before timed food access a bout of activity, defined as food-anticipatory activity (FAA. One notable exception amongst rodents is the Syrian hamster, a photoperiodic species that is not prone to express FAA. The present study was designed to understand the reasons for the low FAA in that species. First, we used both wheel-running activity and general cage activity to assess locomotor behavior. Second, the possible effects of photoperiod was tested by challenging hamsters with restricted feeding under long (LP or short (SP photoperiods. Third, because daytime light may inhibit voluntary activity, hamsters were also exposed to successive steps of full and skeleton photoperiods (two 1-h light pulses simulating dawn and dusk. When hamsters were exposed to skeleton photoperiods, not full photoperiod, they expressed FAA in the wheel independently of daylength, indicating that FAA in the wheel is masked by daytime light under full photoperiods. During FAA under skeleton photoperiods, c-Fos expression was increased in the arcuate nuclei independently of the photoperiod, but differentially increased in the ventromedial and dorsomedial hypothalamic nuclei according to the photoperiod. FAA in general activity was hardly modulated by daytime light, but was reduced under SP. Together, these findings show that food-restricted Syrian hamsters are not prone to display FAA under common laboratory conditions, because of the presence of light during daytime that suppresses FAA expression in the wheel.

  14. SUPPLEMENTARY FEEDING ON THE NUTRIENT BALANCE OF LACTATING DAIRY COW AT CONTRASTING TEMPERATURE REGIMES: ASSESSMENT USING CORNELL NET CARBOHYDRATE AND PROTEIN SYSTEM (CNCPS MODEL

    Directory of Open Access Journals (Sweden)

    A. Jayanegara

    2014-10-01

    Full Text Available Dairy cows often do not receive adequate nutrient supply during their lactation period. This condition caneven be worse if the environmental temperature is not in comfortable range which may occur especially intropical regions. The present research was aimed to simulate the effect of supplementary feeding on nutrientbalance of lactating dairy cow at contrasting temperature regimes using Cornell Net Carbohydrate andProtein System (CNCPS model. Treatments consisted of feeds (R1: Pennisetum purpureum, R2: P.purpureum + concentrate (60:40, R3: P. purpureum + Gliricidia sepium + Leucaena leucocephala(60:20:20, R4: P. purpureum + concentrate + G. sepium + L. leucocephala (60:20:10:10 and environmentaltemperatures (T1: 20 oC, T2: 30 oC. The dairy cow inputs in CNCPS were Holstein breed, body weight of500 kg, feed intake of 15 kg (dry matter basis per day and produced milk 15 kg/day. Based on the CNCPSmodel, there were negative balances of metabolisable energy (ME and metabolisable protein (MP if alactating dairy cow fed only by P. purpureum. The ME balance was worse at higher temperature, while theMP balance was remain unchanged. Addition of concentrate mixture (R2 fulfilled the ME and MPrequirements as well as other nutrients. Addition of leguminous tree leaves (R3 and R4 improved thenutritional status of the lactating cow model compared to R1, but did not better than R2. It was concludedthat supplementary feeding is necessary for improving the nutrient balance of lactating dairy cow, especiallywhen the cow is maintained under uncomfortable environmental temperature.

  15. Photoperiodic flowering: time measurement mechanisms in leaves.

    Science.gov (United States)

    Song, Young Hun; Shim, Jae Sung; Kinmonth-Schultz, Hannah A; Imaizumi, Takato

    2015-01-01

    Many plants use information about changing day length (photoperiod) to align their flowering time with seasonal changes to increase reproductive success. A mechanism for photoperiodic time measurement is present in leaves, and the day-length-specific induction of the FLOWERING LOCUS T (FT) gene, which encodes florigen, is a major final output of the pathway. Here, we summarize the current understanding of the molecular mechanisms by which photoperiodic information is perceived in order to trigger FT expression in Arabidopsis as well as in the primary cereals wheat, barley, and rice. In these plants, the differences in photoperiod are measured by interactions between circadian-clock-regulated components, such as CONSTANS (CO), and light signaling. The interactions happen under certain day-length conditions, as previously predicted by the external coincidence model. In these plants, the coincidence mechanisms are governed by multilayered regulation with numerous conserved as well as unique regulatory components, highlighting the breadth of photoperiodic regulation across plant species.

  16. The effect of sainfoin (Onobrychis viciifolia) and carob pods (Ceratonia siliqua) feeding regimes on the control of lamb coccidiosis.

    Science.gov (United States)

    Saratsis, A; Voutzourakis, N; Theodosiou, T; Stefanakis, A; Sotiraki, S

    2016-06-01

    Recent research has suggested that plants containing condensed tannins may offer a promising alternative approach for the control of coccidiosis in lambs and goat kids. The present study aimed to examine the potential effect of condensed tannins in sainfoin (Onobrychis viciifolia) and carob pods (Ceratonia siliqua) incorporated in sheep rations against lamb coccidiosis. The above tannin-rich sources were studied in three independent feeding trials in which the animals (naturally infected by Eimeria spp. ewes and their lambs) were allocated (i) in the control group and received a tannin-free diet (lucerne hay), or (ii) in the treatment groups and received a tannin-rich diet based on sainfoin hay (in trials 1 and 2), or in carob pod meal and a combination of carob pod meal and sainfoin hay (in trial 3). In total, 95 newborn lambs (and their 73 ewes) were enrolled in all trials which started a month before lambing and ended 8-10 weeks after lambs were born (at weaning). The course of coccidial infection was monitored in lambs by faecal oocyst counts and consistencies which were recorded at weekly intervals. Moreover, lambs total weight gain was evaluated at the end of each trial. During all trials, 100 % of the animals got naturally infected by Eimeria species and the infection burden was higher in trials 2 and 3 compared to trial 1 but in all cases, severe signs of diarrhoea were not observed. Tannin-rich diets were well accepted by the animals not affecting their feed intake and body weight gain when compared to the controls. The results suggest that incorporation of both tannin-rich resources (especially sainfoin) in sheep rations can reduce Eimeria oocyst excretion rates by the lambs, which can decrease subsequently the contamination of the farm environment with the parasite. However, the high variability noted on the results is not allowing us to draw any definite conclusions at least until the potential of those plants is further investigated.

  17. Effect of crop protection and fertilization regimes used in organic and conventional production systems on feed composition and physiological parameters in rats.

    Science.gov (United States)

    Srednicka-Tober, Dominika; Barański, Marcin; Gromadzka-Ostrowska, Joanna; Skwarło-Sońta, Krystyna; Rembiałkowska, Ewa; Hajslova, Jana; Schulzova, Vera; Cakmak, Ismail; Öztürk, Levent; Królikowski, Tomasz; Wiśniewska, Katarzyna; Hallmann, Ewelina; Baca, Elżbieta; Eyre, Mick; Steinshamn, Håvard; Jordon, Teresa; Leifert, Carlo

    2013-02-01

    Very little is known about the effects of an organic or conventional diet on animal physiology and health. Here, we report the effect of contrasting crop protection (with or without chemosynthetic pesticides) and fertilization (manure or mineral fertilizers) regimes on feed composition and growth and the physiological parameters of rats. The use of manure instead of mineral fertilizers in feed production resulted in lower concentrations of protein (18.8 vs 20.6%) and cadmium (3.33 vs 4.92 μg/100 g) but higher concentrations of polyphenols (1.46 vs 0.89 g/100 g) in feeds and higher body protein (22.0 vs 21.5%), body ash (3.59 vs 3.51%), white blood cell count (10.86 vs 8.19 × 10³/mm³), plasma glucose (7.23 vs 6.22 mmol/L), leptin (3.56 vs 2.78 ng/mL), insulin-like growth factor 1 (1.87 vs 1.28 μg/mL), corticosterone (247 vs 209 ng/mL), and spontaneous lymphocyte proliferation (11.14 vs 5.03 × 10³ cpm) but lower plasma testosterone (1.07 vs 1.97 ng/mL) and mitogen stimulated proliferation of lymphocytes (182 vs 278 × 10³ cpm) in rats. There were no main effects of crop protection, but a range of significant interactions between fertilization and crop protection occurred.

  18. Photoperiod response and floral transition in sorghum.

    Science.gov (United States)

    Wolabu, Tezera W; Tadege, Million

    2016-12-01

    Sorghum is a short day plant with strong photoperiod response and its cultivation for grain in temperate regions necessitated the development of photoperiod insensitive mutants that can flower rapidly in the long days of summer. Wild type genotypes grow vegetatively in summer accumulating significant biomass before floral transition ensues during the shorter days of fall. Thus, photoperiod insensitive mutants are grown for grain production while photoperiod sensitive wild type genotypes are grown for forage and biomass feedstock production in the United States. However, the molecular mechanism of photoperiod response and floral transition is poorly understood in sorghum. We have previously reported 3 FLOWERING LOCUS T homologues (SbFT1, SbFT8 and SbFT10) that serve as the ultimate mediators of photoperiod response and floral transition, but more work remains to be done to clearly define the molecular function of the upstream regulatory factors. One of the major QTL that accounts for 85% of the flowering time variation, which was reported to be encoding the PRR37 protein is now debated to be encoding the SbFT12 protein, raising further questions as to how SbFT12 may regulate sorghum florigens. Further molecular analyses will uncover the true nature of the day length sensors in sorghum and the mechanisms of their interactions with florigens to modulate photoperiod dependent vegetative growth and floral transition.

  19. Ultrastructure of the anterior intestinal epithelia of the orange-spotted grouper Epinephelus coioides larvae under different feeding regimes.

    Science.gov (United States)

    Primavera-Tirol, Y H; Coloso, R M; Quinitio, G F; Ordonio-Aguilar, R; Laureta, L V

    2014-04-01

    Enterocytes of the anterior to midsection of the intestine in grouper Epinephelus coioides larvae were compared among different treatments: unfed to the point-of-no-return (PNR), fed natural food only, and co-fed natural food and artificial diet. On day 3, the nutritional condition of unfed grouper larvae regressed with its reduced enterocyte heights which were further degraded on day 4, the PNR, when all the enterocytes were in advanced stages of apoptosis. The apoptosis appeared to be internally directed via the mitochondria. Among day 3 fed larvae, enterocyte heights of those fed artificial diet did not differ from those fed natural food only. Dietary phospholipid deficiency was indicated in larvae co-fed artificial diet on day 3 with an unusually large chylomicron opening into the inter-enterocyte space, and on days 6 and 33 by intestinal steatosis. On day 19, scant to absent lipid droplets in enterocytes of larvae disclosed heightened nutritional requirement preparatory to metamorphosis. As observed in unfed day 3 and premetamorphic day 19 E. coioides, larvae undergoing critical periods and starvation during development employ apoptosis to dispose of degenerated enterocytes that are phagocytosed by adjacent healthy enterocytes without causing inflammatory distress. Upon metamorphosis, grouper larval gut develops better immunity fitness with eosinophilic granule cells observed in the intestinal epithelia of day 33 larvae. Future studies on grouper larval nutrition may consider the appropriate dietary phospholipid levels and larval competence to biosynthesize highly unsaturated fatty acid from linoleic acid vis-à-vis the use of plant ingredients in artificial diet formulations. In vivo challenge tests may validate appropriate dietary nutrient supplementation and lead to better feed formulation, matching the varying energetic demands and digestive capacities of developing E. coioides larvae.

  20. Níveis de hemoglobina, aleitamento materno e regime alimentar no primeiro ano de vida Hemoglobin concentration, breastfeeding and complementary feeding in the first year of life

    Directory of Open Access Journals (Sweden)

    Ana Marlúcia Oliveira Assis

    2004-08-01

    Full Text Available OBJETIVO: Identificar a relação entre os níveis de hemoglobina e o consumo de leite materno, alimentos complementares e líquidos não nutritivos no primeiro ano de vida. MÉTODOS: Estudo transversal envolvendo 553 crianças menores de 12 meses de vida, que freqüentavam os serviços públicos de saúde. A concentração de hemoglobina foi avaliada pelo método cianometahemoglobina, usando-se o sistema HemoCue. Utilizou-se a técnica da regressão linear múltipla para avaliar as associações de interesse. RESULTADOS: Níveis de hemoglobina compatíveis com a anemia foram identificados em 62,8% das crianças investigadas, com maior ocorrência naquelas de seis a 12 meses de idade (72,6%. O aleitamento materno exclusivo nos primeiros seis meses de vida assegurou os mais elevados níveis de hemoglobina. Os demais regimes alimentares declinaram de maneira diferenciada os níveis de hemoglobina, que se tornaram compatíveis com a anemia quando o regime de aleitamento artificial foi adotado (p=0,009. O consumo de chá e/ou água declinou em 0,76 g/dl (pOBJECTIVE: To assess the relationship between hemoglobin concentration and breastfeeding and complementary feeding during the first years of life. METHODS: Cross-sectional study with 553 children under age 12 months, who attended public healthcare facilities. Hemoglobin concentration was measured by the cyanmethaemoglobin method, using the HemoCue system. Associations of interest were analyzed through multiple linear regression. RESULTS: Hemoglobin concentrations compatible with anemia were identified in 62.8% of the children studied, with greater occurrence among the 6-12 months age group (72.6%. Exclusive breastfeeding during the first six months of life was associated with the highest levels of hemoglobin. The remaining feeding regimes were associated with different levels of reduction in hemoglobin levels, which became compatible with anemia in children fed with formula (p=0,009. Tea and

  1. In short photoperiods, human sleep is biphasic.

    Science.gov (United States)

    Wehr

    1992-06-01

    Results of a photoperiod experiment show that human sleep can be unconsolidated and polyphasic, like the sleep of other animals. When normal individuals were transferred from a conventional 16-h photoperiod to an experimental 10-h photo-period, their sleep episodes expanded and usually divided into two symmetrical bouts, several hours in duration, with a 1-3 h waking interval between them. The durations of nocturnal melatonin secretion and of the nocturnal phase of rising sleepiness (measured in a constant routine protocol) also expanded, indicating that the timing of internal processes that control sleep and melatonin, such as circadian rhythms, had been modified by the change in photoperiod. Previous work suggests that the experimental results could be simulated with dual-oscillators, entrained separately to dawn and dusk, or with a two-process model, having a lowered threshold for sleep-onset during the scotoperiod.

  2. Neuroanatomical approaches to the study of insect photoperiodism.

    Science.gov (United States)

    Shiga, Sakiko; Numata, Hideharu

    2007-01-01

    The anatomical locations of three components of insect photoperiodism--the photoperiodic photoreceptor, photoperiodic clock and hormonal effector--are summarized and compared between species. Among photoperiodic photoreceptors, either the retinal or extraretinal types or both are operative, and there is no general relationship between phylogeny and photoreceptor type. The photoperiodic clock comprises time measurement and counter systems. Currently, it is generally accepted that circadian oscillators are involved in the photoperiodic clock. Several recent studies have raised the possibility that timeless, a circadian clock gene, plays a role in the photoperiodic clock in flies. The dorsal protocerebrum has been identified as an important region regulating the endocrine system for adult, pupal and embryonic diapause controlled by photoperiod. In the blow fly Protophormia terraenovae, neural connections between circadian clock neurons and indispensable neurons in the pars lateralis for diapause induction in the dorsal protocerebrum have been demonstrated. This neural network may provide the access needed to investigate the neural components of the photoperiodic clock.

  3. Effect of Light Intensity and Photoperiod on Growth and Biochemical Composition of a Local Isolate of Nostoc calcicola.

    Science.gov (United States)

    Khajepour, Fateme; Hosseini, Seyed Abbas; Ghorbani Nasrabadi, Rasoul; Markou, Giorgos

    2015-08-01

    A study was conducted to investigate the effect of light intensity (21, 42, and 63 μmol photons m(-2) s(-1)) and photoperiod (8:16, 12:12, and 16:8 h light/dark) on the biomass production and its biochemical composition (total carotenoids, chlorophyll a, phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC), total protein, and carbohydrates) of a local isolate of Nostoc calcicola. The results revealed that N. calcicola prefers dim light; however, the most of the levels of light intensity and photoperiod investigated did not have a significant impact on biomass production. Increasing light intensity biomass content of chlorophyll a, PE, PC, APC, and total protein decreased, while total carotenoids and carbohydrate increased. The same behavior was observed also when light duration (photoperiod) increased. The interaction effect of increasing light intensity and photoperiod resulted in an increase of carbohydrate and total carotenoids, and to the decrease of chlorophyll a, PE, PC, APC, and total protein content. The results indicate that varying the light regime, it is capable to manipulate the biochemical composition of the local isolate of N. calcicola, producing either valuable phycobiliproteins or proteins under low light intensity and shorter photoperiods, or producing carbohydrates and carotenoids under higher light intensities and longer photoperiods.

  4. Boar taint, meat quality and fail rate in entire male pigs and male pigs immunized against gonadotrophin releasing factor as related to body weight and feeding regime.

    Science.gov (United States)

    Moore, K L; Mullan, B P; Dunshea, F R

    2017-03-01

    The objective of this experiment was to compare the pork quality of entire male pigs and pigs immunized against GnRF (IC males) at both light (64.8kg) and heavy (106kg) liveweights and two feeding regimes (restricted at 2.5 times maintenance and ad libitum). There was no difference in objective measurements (P>0.05) or eating pork quality (P>0.1) between entire male and IC males. Fail rates were reduced by 9.1% and 12% for pork from IC males for quality grade (P=0.007) and re-purchase intention (P=0.001), respectively, compared to pork from entire males. Skatole (P=0.001) and androstenone (P<0.001) levels in belly fat were higher in entire male than IC male pigs. In addition, 37.5% of the light entire male pigs fed ad libitum showed skatole levels that exceeded the sensory threshold of 0.2μg/g. This work confirms that immunization against GnRF is effective in eliminating boar taint and reducing pork quality fail rates by approximately 10% compared to pork from entire males.

  5. Classification of real farm conditions Iberian pigs according to the feeding regime with multivariate models developed by using fatty acids composition or NIR spectral data

    Directory of Open Access Journals (Sweden)

    De Pedro, Emiliano

    2009-07-01

    Full Text Available Multivariate Classification models to classify real farm conditions Iberian pigs, according to the feeding regime were developed by using fatty acids composition or NIR spectral data of liquid fat samples. A total of 121 subcutaneous fat samples were taken from Iberian pigs carcasses belonging to 5 batches reared under different feeding systems. Once the liquid sample was extracted from each subcutaneous fat sample, it was determined the percentage of 11 fatty acids (C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C20:1. At the same time, Near Infrared (NIR spectrum of each liquid sample was obtained. Linear Discriminant Analysis (LDA was considered as pattern recognition method to develop the multivariate models. Classification errors of the LDA models generated by using NIR spectral data were 0.0% and 1.7% for the model generated by using fatty acids composition. Results confirm the possibility to discriminate Iberian pig liquid samples from animals reared under different feeding regimes on real farm conditions by using NIR spectral data or fatty acids composition. Classification error obtained using models generated from NIR spectral data were lower than those obtained in models based on fatty acids composition.Se han desarrollado modelos multivariantes, generados a partir de la composición en ácidos grasos o datos espectrales NIR, para clasificar según el régimen alimenticio cerdos Ibéricos producidos bajo condiciones no experimentales. Se han empleado 121 muestras de grasa líquida procedentes de grasa subcutánea de canales de cerdos Ibéricos pertenecientes a 5 partidas con regímenes alimenticios diferentes. A dichas muestras líquidas se les determinó el contenido en 11 ácidos grasos (C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C20:1 y se obtuvo su espectro NIR. Los modelos de clasificación multivariantes se desarrollaron mediante Análisis Discriminante Lineal. Dichos

  6. intensive and extensive feeding regimes

    African Journals Online (AJOL)

    1999-07-01

    Jul 1, 1999 ... Anabolic steroids are known to increase muscle protein accretion and should ... nandrolone laurate (which differs from testosterone only in the absence of a methyl group at the C- .... This can be attributed to the fact that part of the protein ..... prenatal Trenbolone Acetate treatment on lamb performance and ...

  7. Photoperiod and reproduction in female deer mice

    Energy Technology Data Exchange (ETDEWEB)

    Whitsett, J.M.; Miller, L.L.

    1982-03-01

    Female deer mice were exposed to a short day photoperiod beginning during 1 of 3 stages of life. In the first experiment, exposure to SD during adulthood resulted in a minimal disruption of reproductive condition; many females bore 2 litters after the onset of this treatment. In the second experiment, females reared on SD from weaning matured normally, as measured by vaginal introitus; however, vaginal closure occurred in approximately one-half of these females by 9 weeks of age. In the third experiment, females were born of mothers housed on either an SD or a long day photoperiod, and were continued on the maternal photoperiod until 6 weeks of postnatal age. The SD photoperiod markedly inhibited reproductive maturation as measured by vaginal patency, ovarian weight, and uterine weight. A comparison of reproductive organ weights and vaginal condition provided evidence for the validity of the latter measure as an index of reproductive state. As assayed by the present testing procedure, the sensitivity of the reproductive system to photoperiod decreases as a function of age in female deer mice.

  8. Photoperiod throughout the maternal life cycle, not photoperiod during seed imbibition, influences germination in Arabidopsis thaliana.

    Science.gov (United States)

    Imaizumi, Toshiyuki; Auge, Gabriela; Donohue, Kathleen

    2017-04-01

    Plants adjust their phenology in response to seasonal cues experienced both by their parents and by themselves, and coordinating responses to these cues is necessary for expressing adaptive phenology. We investigated how cues are integrated across time to influence an important progeny phenotype, i.e., seed germination. We used Arabidopsis thaliana to investigate how the photoperiod experienced by maternal parents and by progeny influences seed germination. We examined when maternal photoperiod effects on germination are imposed and how long they persist in progeny. The photoperiod experienced by maternal plants more strongly influenced germination than the photoperiod experienced during seed imbibition. In addition, the photoperiod experienced at the prereproductive stage frequently influenced germination as strongly as that experienced during reproduction. In general, seeds from plants grown under short days had higher seed germination percentages than seeds from plants grown in longer days. These maternal effects diminished with after-ripening, but reappeared in seeds induced into secondary dormancy. We found no evidence that the effect of photoperiod systematically attenuates in proportion to the time that elapsed between the cue and the timing of seed germination. Moreover, more recently experienced cues did not override the effects of cues experienced previously. Instead, specific sequences of photoperiods experienced at the prereproductive and reproductive stages appear to influence germination behavior. © 2017 Botanical Society of America.

  9. Flowering time: from photoperiodism to florigen.

    Science.gov (United States)

    Ma, H

    1998-09-24

    An Arabidopsis blue-light receptor, Cry2, has been found to play a critical role in the photoperiodic control of flowering time; and genes have been identified that may control the production of a transmissible flower-inducing signal, which may turn out to be the long-elusive putative flowering hormone 'florigen'.

  10. Long-day photoperiod induced unhealthy development of chloroplasts in the photoperiod-sensitive genie male-sterile rice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By measurement of photochemical activities of chloroplasts and observation on supramolecular archi tecture of thylakoids in chloroplasts, it was found that compared with the effects of short-day photoperiod, long-day pho toperiod could induce normal development of chloroplasts in seedlings of NK58S (photoperiod-sensitive genie male-sterile rice) and NK58 (original line) which do not enter the photoperiod sensitive phase and in seedlings of NK58 just enter the photoperiod-sensitive phase. However, it could induce unhealthy development of chloroplasts in seedlings of NK58S which also just enter the photoperiod sensitive phase. This special effect of long-day photoperiod on the development of chloroplasts in NK58S is probably one of main reasons why long-day photoperiod induces rale-sterility in NK58S and normal fertility in NK58.

  11. Mate preference of female blue tits varies with experimental photoperiod.

    Directory of Open Access Journals (Sweden)

    Laura B Reparaz

    Full Text Available Organisms use environmental cues to time their life-cycles and among these cues, photoperiod is the main trigger of reproductive behaviours such as territory defence or song activity. Whether photoperiod is also important for another behaviour closely associated with reproduction, mate choice, is unknown. In many bird species, mate choice occurs at two different times during the annual cycle that strongly differ in daylength: in late winter when photoperiod is short and social mates are chosen, and again around egg-laying when photoperiod is longer and extra-pair mates are chosen. This duality makes the role that photoperiod plays on mate choice behaviours intriguing. We investigated the effect of photoperiod on mate choice using three experimental photoperiodic treatments (9 L:15 D, 14 L:10 D, 18 L:6 D, using blue tits (Cyanistes caeruleus as a biological model. We show that female choice was stronger under long photoperiods. In addition, female blue tits spent significantly more time near males with long tarsi and long wings. This latter preference was only expressed under long photoperiods, suggesting that some indices of male quality only become significant to females when they are strongly photostimulated, and therefore that females could select their social and extra-pair mates based on different phenotypic traits. These results shed light on the roles that photoperiod may play in stimulating pair-bonding and in refining female selectivity for male traits.

  12. Mate preference of female blue tits varies with experimental photoperiod.

    Science.gov (United States)

    Reparaz, Laura B; van Oers, Kees; Naguib, Marc; Doutrelant, Claire; Visser, Marcel E; Caro, Samuel P

    2014-01-01

    Organisms use environmental cues to time their life-cycles and among these cues, photoperiod is the main trigger of reproductive behaviours such as territory defence or song activity. Whether photoperiod is also important for another behaviour closely associated with reproduction, mate choice, is unknown. In many bird species, mate choice occurs at two different times during the annual cycle that strongly differ in daylength: in late winter when photoperiod is short and social mates are chosen, and again around egg-laying when photoperiod is longer and extra-pair mates are chosen. This duality makes the role that photoperiod plays on mate choice behaviours intriguing. We investigated the effect of photoperiod on mate choice using three experimental photoperiodic treatments (9 L:15 D, 14 L:10 D, 18 L:6 D), using blue tits (Cyanistes caeruleus) as a biological model. We show that female choice was stronger under long photoperiods. In addition, female blue tits spent significantly more time near males with long tarsi and long wings. This latter preference was only expressed under long photoperiods, suggesting that some indices of male quality only become significant to females when they are strongly photostimulated, and therefore that females could select their social and extra-pair mates based on different phenotypic traits. These results shed light on the roles that photoperiod may play in stimulating pair-bonding and in refining female selectivity for male traits.

  13. Photoperiodic plasticity in circadian clock neurons in insects

    Directory of Open Access Journals (Sweden)

    Sakiko eShiga

    2013-08-01

    Full Text Available Since Bünning’s observation of circadian rhythms and photoperiodism in the runner bean Phaseolus multiflorus in 1936, many studies have shown that photoperiodism is based on the circadian clock system. In insects, involvement of circadian clock genes or neurons has been recently shown in the photoperiodic control of developmental arrests, diapause. Based on molecular and neuronal studies in Drosophila melanogaster, photoperiodic changes have been reported for expression patterns of the circadian clock genes, subcellular distribution of clock proteins, fiber distribution, or the number of plausible clock neurons in different species. Photoperiod sets peaks of per or tim mRNA abundance at lights-off in Sarcophaga crassipalpis, Chymomyza costata and Protophormia terraenovae. Abundance of per and Clock mRNA changes by photoperiod in Pyrrhocoris apterus. Subcellular Per distribution in circadian clock neurons changes with photoperiod in P. terraenovae. Although photoperiodism is not known in Leucophaea maderae, under longer day length, more stomata and longer commissural fibers of circadian clock neurons have been found. These plastic changes in the circadian clock neurons could be an important constituent for photoperiodic clock mechanisms to integrate repetitive photoperiodic information and produce different outputs based on day length.

  14. Temporal segregation in coexisting spiny mice (genus Acomys): role of photoperiod and heterospecific odor.

    Science.gov (United States)

    Friedman, D; Haim, A; Zisapel, N

    1997-08-01

    Daily rhythms of activity and body temperature were measured in golden spiny mice Acomys russatus, acclimated for 2 weeks, at least, to 2 different photoperiod regimes (16L:8D; 8L:16D) at a constant ambient temperature of 28 degrees C. For recording body temperature, VM-FM (Mini-Mitter Co. Inc., Sunriver, OR) transmitters were implanted. For activity measurements, an infrared sensor (Hengstar BL 68 907F, Japan, using a Lodestar PS-303 power supply, Taiwan) mounted on each cage. Both rhythms were also measured in the same individuals exposed to chemical signals released in the urine of A. cahirinus. The results of this study show that both rhythms of A. russatus correlate and respond to changes in photoperiod regimens, as well as to the chemical signals. However, the correlation changes under the 2 photoperiod regimens. Under LD acclimation, a decrease in the correlation is noted, as a response to the addition of chemical signals. Our results suggest that the different responses due to the different light regimens represent 2 seasons in nature, where presumably each season demands a different physiological response.

  15. Photoperiodic growth control in perennial trees.

    Science.gov (United States)

    Azeez, Abdul; Sane, Aniruddha P

    2015-01-01

    Plants have to cope with changing seasons and adverse environmental conditions. Being sessile, plants have developed elaborate mechanisms for their survival that allow them to sense and adapt to the environment and reproduce successfully. A major adaptive trait for the survival of trees of temperate and boreal forests is the induction of growth cessation in anticipation of winters. In the last few years enormous progress has been made to elucidate the molecular mechanisms underlying SDs induced growth cessation in model perennial tree hybrid aspen (Populus tremula × P. tremuloides). In this review we discuss the molecular mechanism underlying photoperiodic control of growth cessation and adaptive responses.

  16. Effects of "short" photoperiods on seedling growth of Pinus brutia.

    Science.gov (United States)

    Iakovoglou, V; Radoglou, K; Kostopoulou, P; Dini-Papanastasi, O

    2012-03-01

    This study investigated how nurseries could benefit by inducing "short" photoperiods as low as 4 hr to produce "better" seedlings characterized by more vigorous roots; a substantial feature to overcome transplanting stress. The carryover effect of the photoperiod was also investigated on seedlings that grew for 30 days more underthe consistent 14 hr photoperiod. Seedlings of Pinus brutia were subjected to 4, 6, 8 and 14 hr photoperiod for 3 week. Fifteen seedlings were used to evaluate the leaf area, the root and shoot dry weight and their ratio. Six and sixteen seedlings were used to evaluate the shoot electrolyte leakage and the root growth potential, respectively. Based on the results, the 6 and 8 hr photoperiod indicated greater root allocation (4.8 and 4.9 mg, respectively) and chlorophyll content (3.7 and 4.4, respectively). They also indicated greater leaf area values (3.3 and 3.5 cm2, respectively) along with the 14 hr (3.4 cm2). The photoperiod effect continued even after seedlings were subjected at consistent photoperiod. Overall, "short" photoperiods could provide "better" P. brutia seedlings to accommodate immediate massive reforestation and afforestation needs.

  17. Temperature and photoperiod responses of soybean embryos cultured in vitro

    Science.gov (United States)

    Raper, C. D. Jr; Patterson, R. P.; Raper CD, J. r. (Principal Investigator)

    1986-01-01

    Temperature and photoperiod each have direct effects on growth rate of excised embryos of soybean (Glycine max (L.) Merrill). To determine if the effects of photoperiod are altered by temperature, embryos of 'Ransom II' were cultured in vitro at 18, 24, and 30 degrees C under photoperiod durations of 12 and 18 h at an irradiance of 9 W m-2 (700 to 850 nm) and a photosynthetic photon flux density of 58 micromoles m-2 s-1 (400 to 700 nm). Accumulation rates of fresh and dry weight were greater under 18-h than 12-h photoperiods over the entire range of temperature. Water content of the culture embryos was not affected by photoperiod but was greater at 18 and 30 than 24 degrees C. The accumulation rate of dry weight increased from 18 to 26 but declined at 30 degrees C.

  18. Effects of free air carbon dioxide enrichment and drought stress on the feed value of maize silage fed to sheep at different thermal regimes.

    Science.gov (United States)

    Lohölter, Malte; Meyer, Ulrich; Manderscheid, Remy; Weigel, Hans-Joachim; Erbs, Martin; Flachowsky, Gerhard; Dänicke, Sven

    2012-08-01

    Information about the effects of rising atmospheric CO2 concentration and drought on the feed value of maize silage and interactions with the thermal environment during feeding is limited. A free air carbon dioxide enrichment facility was operated in a maize field to generate an elevated CO2 concentration of 550 ppm. Drought was induced by the exclusion of precipitation in one half of all experimental plots. Plants were harvested, chopped and ensiled. In a balance experiment on sheep, the nutrient digestibility was determined for three climatic treatments (temperate, temperature humidity index (THI) 57-63; mild heat, THI 68-71; severe heat, THI 75-80). The CO2 concentration and drought did not alter the crude nutrient content of silage dry matter (DM) or nutrient and organic matter (OM) digestibility. Drought increased the concentration of deoxynivalenol (DON, p maize silage due to increased atmospheric CO2 and drought. Enriched CO2 may decrease DON contaminations during drought. The thermal environment during the balance experiment did not interact with feeding maize silage grown under elevated CO2, but may affect cell wall and OM digestibility.

  19. Effect of different photoperiods on the growth, infectivity and colonization of Trinidadian strains of Paecilomyces fumosoroseus on the greenhouse whitefly, Trialeurodes vaporariorum, using a glass slide bioassay.

    Science.gov (United States)

    Avery, Pasco B; Faull, Jane; Simmonds, Monique S J

    2004-01-01

    Growth, infectivity and colonization rates for blastospores and conidia of Trinidadian strains T, T10, and T11 of Paecilomyces fumosoroseus (Wize) Brown and Smith were assessed for activity against late fourth-instar nymphs of Trialeurodes vaporariorum (Westwood) (Homoptera:Aleyrodidae) under two different photoperiods (24 and 16 hour photophase). A glass-slide bioassay and a fungal development index, modified for both blastospores and conidia, were used to compare the development rates of the fungal strains on the insect hosts. Fewer adult whiteflies emerged from nymphs treated with blastospores and reared under a 16:8 hour light:dark photoperiod than a 24:0 hour photoperiod. Eclosion times of whitefly adults that emerged from nymphs treated with the different strains of conidia were similar over the 8 day experimental period at both light regimes. The percent eclosion of adult whiteflies seems to be directly correlated with the speed of infection of the blastospore or conidial treatment and the photoperiod regime. The longer photophase had a significant positive effect on development index for blastospores; however, a lesser effect was observed for the conidia at either light regime. Blastospore strain T11 offered the most potential of the three Trinidadian strains against T. vaporariorum fourth-instar nymphs, especially under constant light. The glass-slide bioassay was successfully used to compare both blastospores and conidia of P. fumosoroseus. It can be used to determine the pathogenicity and the efficacy of various fungal preparations against aleyrodid pests.

  20. Effect of different feeding regimes on pre-weaning growth rumen fermentation and its influence on post-weaning performance of lambs.

    Science.gov (United States)

    Bhatt, R S; Tripathi, M K; Verma, D L; Karim, S A

    2009-10-01

    Influence of pre-weaning live weight on post-weaning growth performance was assessed on thirty-nine 15-day-old Indian native lambs, randomly fed in three equal groups until 180 days of age. During pre-weaning phase lambs were maintained under feeding regimen of grazing (C-0; Control), grazing and ad lib creep mixture supplementation (C-AL) or grazing, with ad lib creep mixture and milk replacer supplementation (C-ALMR). Lambs were allowed to suckle respective dam in morning and evening till 90 days of age, and fed ad lib green leaves of Ailanthus excelsa after grazing. After weaning all lambs were maintained on grazing and ad lib finisher concentrates supplementation. Pre-weaning performance of lambs in terms of weaning weight (17.2 kg), average daily gain (ADG; 154 g) and feed conversion ratio 3.73 was higher (p < 0.01) in C-ALMR lambs but total gain and ADG were similar among three groups during post-weaning phase. However, improved pre-weaning plane of nutrition and growth rate increased (p < 0.01) finishing weight (FW) of lambs in C-AL, 33 kg and C-ALMR, 32 kg. Dry matter intake was significantly (p < 0.01) higher in C-AL and C-ALMR lambs due to combined effect of feeding. Rumen pH was lowest (p = 0.049) in C-AL lambs. Rumen ciliate protozoa population (10(4)/ml) decreased in C-ALMR lambs (4.3) but increased in C-AL lambs (50.0) more so in C-0 Lambs (19.8). Concentrate feeding of C-AL lamb improved nutrient digestibility. Lambs of C-0 group consumed more DM during post-weaning phase that improved growth performance, while nutrient digestibility was not affected by pre-weaning nutrition. Thus, pre-weaning nutrition has significant influence on FW, however influence of milk replacer feeding on lamb growth need further studies.

  1. Modification Of Photoperiod In Reproduction Of European Seabass (Dicentrarchus Labrax.

    Directory of Open Access Journals (Sweden)

    Edmond Hala

    2012-09-01

    Full Text Available The modification of photoperiod is routinely used in aquaculture with the aim to enhance production by manipulating the timing of reproduction in several important fish species. In European sea bass was proved that photoperiod manipulation plays an important role in different aspects of reproduction performance. The present study review the effects of photoperiod modification on some physiological aspects related to period of spawning, sexual differentiation and early puberty of the sea bass kept in culture conditions. Long photoperiod followed by short ones and applied before the summer solstice, produce advancements of reproductive period, but . Long photoperiod followed by short ones and applied after the summer solstice, produce delays of reproductive period. The modification of photoperiod offers the possibility of controlling the sexual differentiation of sea bass, but is necessary more work to unveil many of its mechanisms of action. The sea bass in culture conditions face the problem of early maturing males or precocious males. Applying the modified photoperiod in a specific time of early gonadal development can reduce the number of the early maturing males of sea bass.

  2. Evolutionary links between circadian clocks and photoperiodic diapause in insects.

    Science.gov (United States)

    Meuti, Megan E; Denlinger, David L

    2013-07-01

    In this article, we explore links between circadian clocks and the clock involved in photoperiodic regulation of diapause in insects. Classical resonance (Nanda-Hamner) and night interruption (Bünsow) experiments suggest a circadian basis for the diapause response in nearly all insects that have been studied. Neuroanatomical studies reveal physical connections between circadian clock cells and centers controlling the photoperiodic diapause response, and both mutations and knockdown of clock genes with RNA interference (RNAi) point to a connection between the clock genes and photoperiodic induction of diapause. We discuss the challenges of determining whether the clock, as a functioning module, or individual clock genes acting pleiotropically are responsible for the photoperiodic regulation of diapause, and how a stable, central circadian clock could be linked to plastic photoperiodic responses without compromising the clock's essential functions. Although we still lack an understanding of the exact mechanisms whereby insects measure day/night length, continued classical and neuroanatomical approaches, as well as forward and reverse genetic experiments, are highly complementary and should enable us to decipher the diverse ways in which circadian clocks have been involved in the evolution of photoperiodic induction of diapause in insects. The components of circadian clocks vary among insect species, and diapause appears to have evolved independently numerous times, thus, we anticipate that not all photoperiodic clocks of insects will interact with circadian clocks in the same fashion.

  3. Effect of Photoperiod On Permethrin Resistance In Aedes aegypti.

    Science.gov (United States)

    Villanueva, O Karina; Ponce, Gustavo; Lopez, Beatriz; Gutierrez, Selene M; Rodriguez, Iram P; Reyes, Guadalupe; Saavedra, Karla J; Black, William C; Garcia, Julian; Beaty, Barry; Eisen, Lars; Flores, Adriana E

    2016-12-01

    Living organisms have been exposed to light-dark cycles that allowed them to adapt to different ecological niches. Circadian cycles affect hormone release, metabolism, and response to xenobiotic compounds. Current studies have shown that insect susceptibility to toxic agents depends on circadian cycles, mainly because the biochemical processes involved in detoxification and responses to oxidative stress are modulated by this process. The goal of this study was to determine the effect of photoperiod on resistance to permethrin in Aedes aegypti . Collections of Ae. aegypti from 4 locations in Yucatan, southern Mexico, were subjected to 2 different photoperiod schemes: dark (0 h light:24 h dark) and natural photoperiod (12 h light:12 h dark). The comparison of both photoperiods was evaluated with respect to permethrin resistance using bottle bioassays and by monitoring the possible mechanism related such as enzymatic activity and by the frequency of 2 knockdown resistance mutations in the voltage-dependent sodium channel gene (V1016I and F1534C). The susceptible strain was used as a reference. The mosquitoes in dark photoperiod showed a reduction in resistance to the pyrethroid. The α-esterases and glutathione S-transferase enzymatic activities showed lower levels in the dark photoperiod, and the frequencies of V1016I knockdown resistance mutation showed significant difference between photoperiod schemes.

  4. Macroeconomic regimes

    NARCIS (Netherlands)

    Baele, L.T.M.; Bekaert, G.R.J.; Cho, S.; Inghelbrecht, K.; Moreno, A.

    2015-01-01

    A New-Keynesian macro-model is estimated accommodating regime-switching behavior in monetary policy and macro-shocks. A key to our estimation strategy is the use of survey-based expectations for inflation and output. Output and inflation shocks shift to the low volatility regime around 1985 and 1990

  5. Desempenho de novilhos F1s Angus-Nelore em pastagens de Brachiaria decumbens submetidos a diferentes regimes alimentares Performance of F1s Angus-Nellore steers on Brachiaria decumbens pasture under different feeding regimes

    Directory of Open Access Journals (Sweden)

    Valéria Pacheco Batista Euclides

    2001-04-01

    Full Text Available O objetivo deste experimento foi avaliar as eficiências biológica e econômica de sistemas de alimentação, durante os períodos críticos, como alternativa de redução da idade de abate de bovinos recriados em pastagens de Brachiaria decumbens. Sessenta bezerros F1s Angus-Nelore desmamados foram distribuídos nos seguintes tratamentos: A sem suplementação; B suplementação somente no primeiro período seco; C suplementação apenas na segunda seca; D suplementação nos dois períodos secos; e E suplementação no primeiro período seco e confinamento no segundo. Os suplementos utilizados foram rações comerciais fornecidas diariamente em quantidades equivalentes a 0,8 e 0,9% do peso vivo, nas primeira e segunda secas, respectivamente. O confinamento durou 100 dias e os novilhos receberam, ad libitum, uma ração contendo 40% de feno de Brachiaria decumbens e 60% de concentrado. O período experimental foi da desmama até o abate (460 kg. Durante o primeiro período seco, os animais suplementados apresentaram maiores ganhos de peso diário (GPD que os não suplementados, 460 e 70 g, respectivamente. Durante o segundo período seco, os animais confinados apresentaram maiores GPD (1.285 g, seguidos dos suplementados em pasto (580 g, enquanto os não suplementados perderam peso (-180 g. Houve aumento na capacidade de suporte dos pastos, onde os animais receberam suplementação, em 24 e 30%, durante os primeiro e segundo períodos secos, respectivamente. Os animais que passaram por restrição alimentar no segundo período seco apresentaram ganho compensatório, quando cessou a restrição, mas esse não foi suficiente para que os animais atingissem pesos de abate à mesma idade dos suplementados. As idades de abate foram 30,1; 28,0; 26,6; 24,2; e 22,0 meses, respectivamente, para os tratamentos A, B, C, D e E. Também foi apresentada a avaliação econômica.The objective of this trial was to evaluate the biological and economical feeding

  6. Primate breeding season: photoperiodic regulation in captive Lemur catta.

    Science.gov (United States)

    Van Horn, R N

    1975-01-01

    Under natural light in Portland, Oreg., captive ring-tailed lemurs (Lemur catta) experience a breeding season that differs by nearly half a year from the season in Madagascar. A series of experimental day length changes from 1971 to 1974 demonstrated the ability of both temperate and tropical photoperiod cycles to induce estrous cycles in quiescent animals. After photoperiodic activation, most impregnated females failed to resume estrous cycles even after infant separations unless they received additional photoperiod changes. Unimpregnated females, on the other hand, showed no significant decline in the incidence of estrous cycles under prolonged exposure to a constant day length regimen (12.OL:12.OD) for over a year.

  7. Phonon-dressed Mollow triplet in the regime of cavity quantum electrodynamics: excitation-induced dephasing and nonperturbative cavity feeding effects.

    Science.gov (United States)

    Roy, C; Hughes, S

    2011-06-17

    We study the resonance fluorescence spectra of a driven quantum dot placed inside a high-Q semiconductor cavity and interacting with an acoustic phonon bath. The dynamics is calculated using a time-convolutionless master equation in the polaron frame. We predict pronounced spectral broadening of the Mollow sidebands through off-resonant cavity emission which, for small cavity-coupling rates, increases quadratically with the Rabi frequency in direct agreement with recent experiments using semiconductor micropillars [S. M. Ulrich et al., preceding Letter, Phys. Rev. Lett. 106, 247402 (2011)]. We also demonstrate that, surprisingly, phonon coupling actually helps resolve signatures of the elusive second rungs of the Jaynes-Cummings ladder states via off-resonant cavity feeding. Both multiphonon and multiphoton effects are shown to play a qualitatively important role on the fluorescence spectra.

  8. Increased sensitivity of the circadian system to temporal changes in the feeding regime of spontaneously hypertensive rats - a potential role for Bmal2 in the liver.

    Directory of Open Access Journals (Sweden)

    Lenka Polidarová

    Full Text Available The mammalian timekeeping system generates circadian oscillations that rhythmically drive various functions in the body, including metabolic processes. In the liver, circadian clocks may respond both to actual feeding conditions and to the metabolic state. The temporal restriction of food availability to improper times of day (restricted feeding, RF leads to the development of food anticipatory activity (FAA and resets the hepatic clock accordingly. The aim of this study was to assess this response in a rat strain exhibiting complex pathophysiological symptoms involving spontaneous hypertension, an abnormal metabolic state and changes in the circadian system, i.e., in spontaneously hypertensive rats (SHR. The results revealed that SHR were more sensitive to RF compared with control rats, developing earlier and more pronounced FAA. Whereas in control rats, the RF only redistributed the activity profiles into two bouts (one corresponding to FAA and the other corresponding to the dark phase, in SHR the RF completely phase-advanced the locomotor activity according to the time of food presentation. The higher behavioral sensitivity to RF was correlated with larger phase advances of the hepatic clock in response to RF in SHR. Moreover, in contrast to the controls, RF did not suppress the amplitude of the hepatic clock oscillation in SHR. In the colon, no significant differences in response to RF between the two rat strains were detected. The results suggested the possible involvement of the Bmal2 gene in the higher sensitivity of the hepatic clock to RF in SHR because, in contrast to the Wistar rats, the rhythm of Bmal2 expression was advanced similarly to that of Bmal1 under RF. Altogether, the data demonstrate a higher behavioral and circadian responsiveness to RF in the rat strain with a cardiovascular and metabolic pathology and suggest a likely functional role for the Bmal2 gene within the circadian clock.

  9. Plant adaptation to temperature and photoperiod

    Directory of Open Access Journals (Sweden)

    O. JUNTTILA

    2008-12-01

    Full Text Available Plants respond to environmental conditions both by adaptation and by acclimation. The ability of the plants to grow, reproduce and survive under changing climatic conditions depends on the efficiency of adaptation and acclimation. The adaptation of developmental processes in plants to temperature and photoperiod is briefly reviewed. In annual plants this adaptation is related to growth capacity and to the timing of reproduction. In perennial plants growing under northern conditions, adaptation of the annual growth cycle to the local climatic cycle is of primary importance. Examples of the role of photothermal conditions in regulation of these phenological processes are given and discussed. The genetic and physiological bases for climatic adaptation in plants are briefly examined.;

  10. Photoperiod Adaptation of Quinoa (Chenopodium quinoa Willd.)

    DEFF Research Database (Denmark)

    Bendevis, Mira Arpe

    The global interest in quinoa (Chenopodium quinoa Willd.) is rapidly increasing, both as a result of its nutritional qualities but also due to its potential as an alternative crop in regions, such as the Mediterranean and Western Australia, where increasing soil salinity and extended periods...... of drought are the major constraints on agricultural productivity. However, quinoa originates from the Andean region and the majority of available cultivars are facultative short day plants and exhibit severely reduced, or completely disrupted, seed production under day lengths longer than 12 hours....... The inherent photoperiod sensitivity poses a challenge to future success of quinoa in regions outside its centre of origin. The existence of day length neutral quinoa cultivars provide an attractive alternative for cultivation in regions outside the tropical zone, as well as a valuable tool to compare adaptive...

  11. Interactive effects of photoperiod and light intensity on blood physiological and biochemical reactions of broilers grown to heavy weights.

    Science.gov (United States)

    Olanrewaju, H A; Purswell, J L; Collier, S D; Branton, S L

    2013-04-01

    The effects of photoperiod, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. A 3 × 3 factorial experiment in a randomized complete block design was used in this study. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d, and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8 to 56, regular/intermittent (2L:2D), and short/nonintermittent (8L:16D) from d 8 to 48 and 23L:1D from d 49 to 56, respectively] and exposure to 3 light intensities (10, 5.0, and 0.5 lx) from d 8 through d 56 at 50% RH. Feed and water were provided ad libitum. Venous blood samples were collected on d 7, 14, 28, 42, and 56. Main effects indicated that short/nonintermittent photoperiod significantly (P light intensity, or their interaction. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during photoperiod and light intensity exposure did not deteriorate despite a lower pH and higher partial pressure of CO2 with normal HCO3(-). These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on blood physiological variables, whereas the short photoperiod markedly affected most blood physiological variables without inducing physiological stress in broilers.

  12. Transcriptional regulation of the ADP-glucose pyrophosphorylase isoforms in the leaf and the stem under long and short photoperiod in lentil.

    Science.gov (United States)

    Seferoglu, Ayse Bengisu; Baris, Ibrahim; Morgil, Hande; Tulum, Isil; Ozdas, Sule; Cevahir, Gul; Kavakli, Ibrahim Halil

    2013-05-01

    ADP-glucose pyrophosphorylase (AGPase) is a key enzyme in plant starch biosynthesis. It contains large (LS) and small (SS) subunits encoded by two different genes. In this study, we explored the transcriptional regulation of both the LS and SS subunits of AGPase in stem and leaf under different photoperiods length in lentil. To this end, we first isolated and characterized different isoforms of the LS and SS of lentil AGPase and then we performed quantitative real time PCR (qPCR) to see the effect of photoperiod length on the transcription of the AGPase isforms under the different photoperiod regimes in lentil. Analysis of the qPCR results revealed that the transcription of different isoforms of the LSs and the SSs of lentil AGPase are differentially regulated when photoperiod shifted from long-day to short-day in stem and leaves. While transcript levels of LS1 and SS2 in leaf significantly decreased, overall transcript levels of SS1 increased in short-day regime. Our results indicated that day length affects the transcription of lentil AGPase isoforms differentially in stems and leaves most likely to supply carbon from the stem to other tissues to regulate carbon metabolism under short-day conditions. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. Effect of photoperiod on sexual activity of boar

    Directory of Open Access Journals (Sweden)

    Radomir Savić

    2015-08-01

    Full Text Available The main objective of this study was to assess the effect of photoperiod on sexual activity of three breeds of boars: Swedish Landrace (n=34, Large White (n=38, and Duroc (n=32. Boar sexual activity was analysed based on the libido index and intensity of ejaculation. The libido index was calculated as the ratio between the duration of ejaculation and time of preparation until ejaculation. The intensity of ejaculation was the volume of ejaculate (mL secreted in the unit of time (min. The effect of photoperiod was analysed as the effect of duration of daylight (12 h within photoperiod intervals (increasing and decreasing. Impact assessment was carried out by applying the General Linear Model procedure. Libido and intensity of ejaculation varied under the impact of photoperiod and the breed of boars. With the increase in age, the boar libido weakened, while the volume of ejaculate and intensity of ejaculation increased. Boars manifested better libido when the daylight lasted longer than 12 h in both photoperiod intervals. Different from libido, the volume of ejaculate and intensity of ejaculation were highest when the daylight was shorter than 12 h, but only in the decreasing photoperiod interval. Swedish Landrace boars manifested best libido, while in the production of sperm the Duroc boars were inferior compared with Swedish Landrace and Large White. The phenotypic relationship among libido, ejaculate volume, and ejaculation intensity ranges from very low to high; however, the coefficients were positive, which indicates the possibility of simultaneous improvement of these traits.

  14. Time to flower: interplay between photoperiod and the circadian clock.

    Science.gov (United States)

    Johansson, Mikael; Staiger, Dorothee

    2015-02-01

    Plants precisely time the onset of flowering to ensure reproductive success. A major factor in seasonal control of flowering time is the photoperiod. The length of the daily light period is measured by the circadian clock in leaves, and a signal is conveyed to the shoot apex to initiate floral transition accordingly. In the last two decades, the molecular players in the photoperiodic pathway have been identified in Arabidopsis thaliana. Moreover, the intricate connections between the circadian clockwork and components of the photoperiodic pathway have been unravelled. In particular, the molecular basis of time-of-day-dependent sensitivity to floral stimuli, as predicted by Bünning and Pittendrigh, has been elucidated. This review covers recent insights into the molecular mechanisms underlying clock regulation of photoperiodic responses and the integration of the photoperiodic pathway into the flowering time network in Arabidopsis. Furthermore, examples of conservation and divergence in photoperiodic flower induction in other plant species are discussed. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. Photoperiodic modulation of thyroid hormone receptor (TR-α), deiodinase-2 (Dio-2) and glucose transporters (GLUT 1 and GLUT 4) expression in testis of adult golden hamster, Mesocricetus auratus.

    Science.gov (United States)

    Verma, Rakesh; Haldar, Chandana

    2016-12-01

    Phenomenon of seasonal reproduction is being regulated by changes in day length or photoperiod. The molecular mechanism underlying the event of photoperiodic regulation of testis and thyroid functions along with glucose uptake transporters has never been reported for golden hamster, M. auratus. The present study was performed to investigate the effect of photoperiod on the expression of key thyroid hormone receptor (TR-α), deiodinase-2 (Dio-2) and glucose uptake transporters (GLUT-1 & GLUT-4) in testicular germ cell and Leydig cells, and its correlation with the testicular androgen receptor (AR), germ cell proliferation factor (PCNA) and cell survival factor (Bcl-2) in testis of adult golden hamster, Mesocricetus auratus. Hamsters were exposed to different photoperiodic regimes i.e. critical photoperiod (CP), short day (SD) and long day (LD) for 10weeks. LD induces upregulation of thyroidal and gonadal activity as evident by active thyroid gland and testicular histoarchitecture, peripheral total thyroid (tT3, tT4) and testosterone hormone profiles when compared with SD exposed hamsters. Further, LD increased the expression of testicular TR-α, Dio-2, GLUT-1, GLUT-4 along with testicular AR and glucose content thereby enhancing germ cell proliferation and survival as reflected by increased PCNA and Bcl-2 expression when compared to SD exposed hamsters. Thus, it can be suggested that testicular thyroid hormone status is being regulated by photoperiod and is possibly involved in seasonal adaptation to reproductive phenomenon of golden hamster.

  16. Apparent dissociation of photoperiodic time measurement between vernal migration and breeding under dim green light conditions in Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii

    Institute of Scientific and Technical Information of China (English)

    Gang WANG; Marilyn RAMENOFSKY; John C.WINGFIELD

    2013-01-01

    In seasonally breeding birds,the annual cycle of photoperiod is a principal environmental cue for temporal arrangement of different life-history stages,such as migration and breeding.In the past,most research has focused on the mechanisms of photoperiodic control of breeding with less attention paid to migration.In Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii (GWCS),photoreceptors for induction of breeding are known to reside in the basal hypothalamus.However,it is unknown whether the sites of photoperiodic reception for vernal migration are the same as those for breeding.Therefore,we hypothesized that they may be controlled separately.In this study,we exposed photosensitive GWCSs to low-penetration green light (wavelength at 510 rm) under a regime of 1 lux during the day and <0.1 lux at night,and switched the photoperiodic conditions from short day (10 h daytime) to long day (18 h daytime).The results showed that the experimental birds developed traits associated with vernal migration including mass increase,fat deposition and migratory restlessness behavior when transferred from short day to long day green light cycles,while control birds maintained continuously on short day green light conditions did not express any migration related characteristics.Neither experimental nor control groups showed gonadal recrudescence under either green light cycles.In support of our hypothesis,we were able to apparently dissociate the photoperiodic responses regulating vernal migration and breeding,which suggests separate mechanisms ofphotoperiodic time measurement.Such distinct photoperiodic mechanisms may drive the fine-tuned temporal arrangement of the two life history stages.

  17. Desempenho larval do camarão-d'água-doce (Macrobrachium rosenbergii De Man, 1879 submetido a diferentes regimes alimentares Larval performance of the freshwater prawn (Macrobrachium rosenbergii De Man, 1879 submitted to different feeding systems

    Directory of Open Access Journals (Sweden)

    Luciana Almada Thomaz

    2004-12-01

    Full Text Available O desempenho das larvas de Macrobrachium rosenbergii submetidas a quatro diferentes regimes alimentares foi verificado utilizando a observação diária dos subestádios larvais e as primeiras metamorfoses. As larvas foram estocadas em densidade de aproximadamente 100 larvas.l-1, em 16 tanques retangulares, com capacidade de 33 litros. O experimento foi dividido em quatro unidades experimentais (blocos, nos quais foram testados quatro regimes alimentares na larvicultura em circuito aberto, com quatro repetições por tratamento. Os regimes alimentares substituindo progressivamente náuplio de Artemia sp. (nas pelo rotífero Brachionus plicatilis (rots foram os seguintes tratamentos: 100% Brachionus plicatilis (30 rots/mL (T1; 100% Artemia (5 nas/ mL (T2, 60% Artemia (3 nas/mL + 40% Brachionus plicatilis (12 rots/ mL (T3 e 40% Artemia (2 nas/mL + 60% Brachionus plicatilis (18 rots/ mL (T4, sendo adicionada a estes tratamentos ração úmida. Os resultados da mudança dos subestádios larvais demonstraram que não houve diferença significativa entre os tratamentos T2, T3 e T4. No tratamento T1 (100% Brachionus plicatilis houve mortalidade total no 14º dia do experimento. O efeito da ocorrência das primeiras metamorfoses para pós-larvas, ocorreu ao 27º dia nos tratamentos T2, T3 e T4. Conseqüentemente, o ciclo de larvicultura até a metamorfose de 90% para pós-larva (PL1 foi o mesmo nos tratamentos (35 dias. Portanto, a utilização do rotífero enriquecido e congelado no regime alimentar das larvas permitiu desempenho satisfatório em termos de desenvolvimento larval de M. rosenbergii até a passagem para o estádio de pós-larva.The feeding is one of the most important factors to larval development and the sucess of the commercial cultivation of decapod crustacean larvae depends on the efficient and economic utilization of the available food. The performance of Macrobrachium rosenbergii larva submitted to four different feeding systems was

  18. Adaptation to short photoperiods augments circadian food anticipatory activity in Siberian hamsters.

    Science.gov (United States)

    Bradley, Sean P; Prendergast, Brian J

    2014-06-01

    This article is part of a Special Issue "Energy Balance". Both the light-dark cycle and the timing of food intake can entrain circadian rhythms. Entrainment to food is mediated by a food entrainable circadian oscillator (FEO) that is formally and mechanistically separable from the hypothalamic light-entrainable oscillator. This experiment examined whether seasonal changes in day length affect the function of the FEO in male Siberian hamsters (Phodopus sungorus). Hamsters housed in long (LD; 15 h light/day) or short (SD; 9h light/day) photoperiods were subjected to a timed-feeding schedule for 10 days, during which food was available only during a 5h interval of the light phase. Running wheel activity occurring within a 3h window immediately prior to actual or anticipated food delivery was operationally-defined as food anticipatory activity (FAA). After the timed-feeding interval, hamsters were fed ad libitum, and FAA was assessed 2 and 7 days later via probe trials of total food deprivation. During timed-feeding, all hamsters exhibited increases FAA, but FAA emerged more rapidly in SD; in probe trials, FAA was greater in magnitude and persistence in SD. Gonadectomy in LD did not induce the SD-like FAA phenotype, indicating that withdrawal of gonadal hormones is not sufficient to mediate the effects of photoperiod on FAA. Entrainment of the circadian system to light markedly affects the functional output of the FEO via gonadal hormone-independent mechanisms. Rapid emergence and persistent expression of FAA in SD may reflect a seasonal adaptation that directs behavior toward sources of nutrition with high temporal precision at times of year when food is scarce.

  19. Reproductive phenology of the American Bullfrog in subtropical Brazil: photoperiod as a main determinant of seasonal activity

    Directory of Open Access Journals (Sweden)

    CAMILA I. MEDEIROS

    2016-01-01

    Full Text Available ABSTRACT The North American bullfrog Lithobates catesbeianus continues to invade ecosystems worldwide, potentially causing population declines and even extinctions. Within its native distribution, bullfrogs show prolonged reproductive seasons and high fertility. However, data on breeding biology of bullfrogs ex-situ in invaded localities mainly comes from anecdotal reports. Understanding how invasive species are adjusting their life histories to new colonized environments is important for conservation purposes. Here we describe temporal and spatial abundance, calling activity, spawning and tadpole distribution of bullfrogs in southern Brazil. Eighteen samplings occurred during one year. The abundance of individuals was positively related to longer photoperiods and higher temperatures. Reproductive activity was also positively associated with longer photoperiods. Calling sites, spawning and tadpoles were associated with microhabitats presenting hydrophytes, which may provide shelter and thermal stability to bullfrogs. The reproductive seasonal activity of bullfrogs can be highly variable across its growing geographical range, but in subtropical Brazil it is associated with photoperiod, a highly predictable abiotic determinant. In our study area, bullfrogs presented a breeding season twice as long as that observed in some native localities. We suggest that management strategies directed to bullfrog populations must consider the habitat structures and seasonal regimes determined by each invaded environment.

  20. Effects of shortened photoperiod on gonadotropin-releasing hormone, gonadotropin, and vitellogenin gene expression associated with ovarian maturation in rainbow trout.

    Science.gov (United States)

    Choi, Sungchang; Lee, Cheul Ho; Park, Woodong; Kim, Dae-Jung; Sohn, Young Chang

    2010-01-01

    Reproductive activities of salmonids are synchronized by changes in photoperiod, which control the endocrine system via the brain-pituitary-gonadal axis. Gonadotropin-releasing hormone (GnRH) in the brain regulates synthesis and release of the pituitary gonadotropins (GTHs; FSH and LH). FSH and LH in turn stimulate the production of sex steroids for oocyte growth and maturation-Inducing steroid hormones for oocyte maturation and ovulation, respectively, in female salmonids. To clarify effects of long-term photoperiod manipulations on the reproductive activity of salmonids from early recrudescence to ovulation, we Investigated the gene expression profiles of GnRH, GTHs, and vitellogenin (VTG), and plasma sex steroids in female rainbow trout (Oncorhynchus mykiss). In addition, the percentages of eyed embryos and hatched alevins were examined together with the number of ovulated eggs to evaluate the effects of photoperiod regimes on egg quality. During late summer, the mRNA levels of GnRHs, GTHalpha, and LHbeta, and the plasma level of a maturational steroid (17alpha,20beta-dihydroxy-4-pregnen-3-one; 17,20beta-P) were significantly elevated by a gradually shortened photoperiod under constant temperature, in accordance with accelerated sexual maturation. The percentages of eyed embryos and hatched alevins from fish ovulated in August were comparable to those of control fish observed in December. These results clearly indicate that syntheses of GnRHs, LH, VTG, and 17,20beta-P are effectively accelerated by a programmed long-short photoperiod regime in early recrudescent female rainbow trout, without a marked deterioration in egg quality.

  1. Effects of different food composition and feeding regimes on growth and reproduction of Moina mongolica Daday%不同食物组合与投喂方法对蒙古裸腹溞生长和生殖的影响

    Institute of Scientific and Technical Information of China (English)

    王岩; 李轩

    2004-01-01

    A laboratory experiment was carried out to evaluate effects of different food composition and feeding regimes on growth and reproduction of Moina mongolica Daday. Three food composition (1×106cells·mL-1 Chlorella sp. +2×10-5g·mL-1 baker's yeast, 1.5×106 cells·mL-1 Chlorella sp. +1.5×10-5g·mL-1 baker's yeast, 2×106 cells·mL-1 Chlorella sp. +1.0×10-5g·mL-1 baker's yeast) and two feeding regimes (feeding the M. mongolica mixture of Chlorella sp. and baker's yeast everyday, or Chlorella sp. and baker's yeast alternately) were examined in the experiment. There were no significant differences in increment of body length,age at maturity, intervals between broods, brood number, brood size and total reproductive output between the M.mongolica fed with different mixed food using same feeding regimes. Lower daily reproductive output, however,was observed in the individuals fed mixed food containing 1.0×106 cells·mL-1 Chlorella sp. and 2×10-5g.mL-1 baker's yeast. When fed the mixed food with same composition, the M.mongolica that were fed mixture of Chlorella sp. and baker's yeast dally did not exhibit significantly different growth and reproduction performances compared to the individuals fed Chlorella sp. and baker's yeast altemately. The results suggest the mixture of 1.5×106cells·mL-1 Chlorella sp. +1.0×10-5g·mL-1 baker's yeast is a nutritionally adequate food item for M.mongolica, and flexible feeding regime, feeding the animal either with mixture of Chlorella sp. and baker's yeast dally or with Chlorella sp. and baker's yeast alternately, can be used in commercial production of M. mongolica.

  2. Environmental stress and flowering time: the photoperiodic connection.

    Science.gov (United States)

    Riboni, Matteo; Robustelli Test, Alice; Galbiati, Massimo; Tonelli, Chiara; Conti, Lucio

    2014-01-01

    Plants maximize their chances to survive adversities by reprogramming their development according to environmental conditions. Adaptive variations in the timing to flowering reflect the need for plants to set seeds under the most favorable conditions. A complex network of genetic pathways allows plants to detect and integrate external (e.g., photoperiod and temperature) and/or internal (e.g., age) information to initiate the floral transition. Furthermore different types of environmental stresses play an important role in the floral transition. The emerging picture is that stress conditions often affect flowering through modulation of the photoperiodic pathway. In this review we will discuss different modes of cross talk between stress signaling and photoperiodic flowering, highlighting the central role of the florigen genes in this process.

  3. Effects of spectral composition, photoperiod and light intensity on the gonadal development of Atlantic salmon Salmo salar in recirculating aquaculture systems (RAS)

    Science.gov (United States)

    Qiu, Denggao; Xu, Shihong; Song, Changbin; Chi, Liang; Li, Xian; Sun, Guoxiang; Liu, Baoliang; Liu, Ying

    2015-01-01

    Artificial lighting regimes have been successfully used to inhibit sexual maturity of Atlantic salmon in confinement. However, when these operations are applied in commercial recirculating aquaculture systems (RAS) using standard lighting technology, sexual maturation is not suppressed. In this study, an L9 (33) orthogonal design was used to determine the effects of three factors (spectral composition, photoperiod, and light intensity) on the gonadal development of Atlantic salmon in RAS. We demonstrated that the photoperiod at the tested levels had a much greater effect on the gonadosomatic index and female Fulton condition factor than spectral composition and light intensity. The photoperiod had a significant effect on the secretion of sex steroids and melatonin ( P0.05). The optimum lighting levels in female and male Atlantic salmon were LD 8:16, 455 nm (or 625 nm), 8.60 W/m2; and LD 8:16, 8.60 W/m2, 455 nm respectively. These conditions not only delayed gonadal development, but also had no negative effects on Atlantic salmon growth in RAS. These results demonstrate that a combination of spectral composition, photoperiod and light intensity is effective at delaying the gonadal development of both male and female salmon in RAS.

  4. Effects of photoperiod, plant growth regulators and culture media on in vitro growth of seedlings of Cyrtochilum loxense (Lindl. Kraenzl. an endemic and endangered orchid from Ecuador

    Directory of Open Access Journals (Sweden)

    Yadira González

    2014-10-01

    Full Text Available Cyrtochilum loxense (Lindl. Kraenzl. is an endemic and seriously endangered orchid species endemic in the Loja Province (Southern Ecuador. The main goals of this research were to analyze how culture media, plant growth regulators and photoperiod affect the growth of C. loxense. Eight month old plants (approximate 1 – 1.5 cm in height obtained by in vitro germination, were cultivated on MS media or Knudson C; MS with three levels of naphthalene acetic acid (NAA and 6-benzylaminopurine (BAP (2/0.5; 1/0.5 y 0.5/ 0.5 mg-1L; and three photoperiodic regimes (24/0, 16/8, 8/16 h on MS with and without plant growth regulators. No significant differences of shoot induction were observed on media with or without plant growth regulators, and all tested photoperiods. The highest growth (1.2 cm was observed in plantlets cultivated on growth regulator-free media with a 16/8 photoperiod. Also the shoot and root formation was better in this species in absence of plant growth regulators. Probably this response is due to the endogenous hormone levels in the tissues or due to the kind and concentrations of PGRs used were too low to induce positive morphogenetic responses.

  5. Photoperiod and feeding behavior of the Antarctic fish Notothenia rossii (Perciformes: Nototheniidae and functional morphology of chemical and visual sensory structures used in foraging Comportamento alimentar do peixe antártico Notothenia rossii (Perciformes: Nototheniidae em diferentes fotoperíodos e a morfologia funcional das estruturas quimio-foto sensoriais usadas na detecção do alimento

    Directory of Open Access Journals (Sweden)

    Lucélia Donatti

    2008-06-01

    Full Text Available The influence of photoperiod on the ability of Notothenia rossii Richardson, 1844 to detect prey was studied experimentally. In 12L/12D there was the highest number of individuals stimulated visually and chemically while in 24D chemical perception was the same as that observed in 12L/12D, the latter being lower than in 24L. The ultrastructure of chemo- and photo-sensory structures, involved in the detection of food, was studied. The photoreceptor cells of the retina are single and double cones, and rods. Taste buds were concentrated in the central part of upper and lower lips. Their shape is even, but the size is variable. The olfactory rosette has a sensory and a non-sensory epithelium, being rich in different mucosubstances. The conclusion was that in different photoperiods there is a difference in the response to visual and chemical stimulation for prey detection and that all sensory systems are more stimulated in periods of more luminosity, mainly when there is an alternation between light and dark periods. Sensory organs are complex when compared to some other Antarctic fish such as Gobionotothen gibberifrons Lönnberg, 1905 and Ophthalmolycus amberensis Tomo, Marshoff & Torno, 1977 but similar to those of N. coriiceps Rchardson, 1844.A capacidade de Notothenia rossii Richardson, 1844 detectar presas in diferentes fotoperíodos (24L, 24D e 12L/12D foi estudada em tanques experimentais. Em 12L/12D houve um maior número de indivíduos estimulados visual e quimicamente enquanto que em 24D a percepção química foi a mesma que a observada em 12L/12D, sendo este ultimo inferior a 24L. A morfologia das estruturas quimio-foto sensoriais, envolvidas na detecção do alimento, foi estudada. As células fotorreceptoras da retina são os cones simples e duplos e os bastonetes. Os botões concentraram-se na região central dos lábios superior e inferior. Seu formato é constante, mas o tamanho é variável. A rosseta olfatória possui um epit

  6. Quantifying the Effects of Photoperiod, Temperature and Daily Irradiance on Flowering Time of Soybean Isolines

    Directory of Open Access Journals (Sweden)

    Elroy R. Cober

    2014-11-01

    Full Text Available Soybean isolines with different combinations of photoperiod sensitivity alleles were planted in a greenhouse at different times during the year resulting in natural variation in daily incident irradiance and duration. The time from planting to first flower were observed. Mathematical models, using additive and multiplicative modes, were developed to quantify the effect of photoperiod, temperature, photoperiod-temperature interactions, rate of photoperiod change, and daily solar irradiance on flowering time. Observed flowering times correlated with predicted times (R2 = 0.92, Standard Error of the Estimate (SSE = 2.84 d, multiplicative mode; R2 = 0.91, SSE = 2.88 d, additive mode. The addition of a rate of photoperiod change function and an irradiance function to the temperature and photoperiod functions improved the accuracy of flowering time prediction. The addition of a modified photoperiod function, which allowed for photoperiod sensitivity at shorter photoperiods, improved prediction of flowering time. Both increasing and decreasing rate of photoperiod change, as well as low levels of daily irradiance delayed flowering in soybean. The complete model, which included terms for the rate of photoperiod change, photoperiod, temperature and irradiance, predicted time to first flower in soybean across a range of environmental conditions with an SEE of 3.6 days when tested with independent data.

  7. Regimes internacionais

    OpenAIRE

    Meireles, André Bezerra

    2004-01-01

    Dissertação (mestraddo) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas. Programa de Pós-Graduação em Direito. Qual o papel dos regimes internacionais com relação ao comportamento dos agentes das relações internacionais contemporâneas, em especial, o Estado? Dentro das negociações de uma esfera internacional caracterizada por uma forte interdependência econômica, verificada a existência de múltiplos canais de conexões entre as sociedades, e uma tendência contínua p...

  8. Photoperiodism : Shall EYA Compare Thee to a Summer's Day?

    NARCIS (Netherlands)

    Hut, Roelof A.

    2011-01-01

    Seasonal changes in day length are used by plants and animals to synchronize annual rhythms in reproduction, physiology, and behavior to the environment. Increasing day length during spring causes sudden changes in the mammalian reproductive system once the critical photoperiod is reached. The molec

  9. Short day photoperiod protects against acetaminophen-induced ...

    African Journals Online (AJOL)

    Prof. Ogunji

    long photoperiod while these parameters were significantly (P<0.05) reduced in rats subjected to short .... Values are mean ± SEM with n=6. *P<0.05, ... result to serious liver injury or death in humans. (Watkins ... the rate-limiting enzyme in melatonin synthesis. (Illnerova ... Day length affects immune cells numbers in deer.

  10. Flower Development and Photoperiodic Control of Flowering in Rice

    Institute of Scientific and Technical Information of China (English)

    XIANG Chao; QU Li-jun; GAO Yong-ming; SHI Ying-yao

    2013-01-01

    Floral transition,which is referred to as a plant's transition from vegetative stage to reproductive stage,is considered to be a critical developmental switch in higher plants,for a timely flowering is a major factor of reproductive success.Endogenous and environmental cues,such as photoperiod,light quality,plant hormones concentrations and temperature,provide information to the plants whether the environment is favorable for flowering.These cues promote,or prevent,flowering through a complex genetic network,mediated by a careful orchestration of temporal and spatial gene expression.One of such cues is photoperiod.Rice (Oryza sativa L.) serves as a powerful model species for the understanding of flowering in higher plants,including flower development and photoperiodic control of flowering.In this review,we overviewed and discussed the flower development and its model.We also overviewed the photoperiodic pathways in rice flowering control,and summarized the pathways at molecular level.

  11. Photoperiodic Regulation of Florigen Function in Arabidopsis thaliana.

    Science.gov (United States)

    Golembeski, Greg S; Imaizumi, Takato

    2015-01-01

    One mechanism through which flowering in response to seasonal change is brought about is by sensing the fluctuation in day-length; the photoperiod. Flowering induction occurs through the production of the florigenic protein FLOWERING LOCUS T (FT) and its movement from the phloem companion cells in the leaf vasculature into the shoot apex, where meristematic reprogramming occurs. FT activation in response to photoperiod condition is accomplished largely through the activity of the transcription factor CONSTANS (CO). Regulation of CO expression and protein stability, as well as the timing of other components via the circadian clock, is a critical mechanism by which plants are able to respond to photoperiod to initiate the floral transition. Modulation of FT expression in response to external and internal stimuli via components of the flowering network is crucial to mediate a fluid flowering response to a variety of environmental parameters. In addition, the regulated movement of FT protein from the phloem to the shoot apex, and interactions that determine floral meristem cell fate, constitute novel mechanisms through which photoperiodic information is translated into flowering time.

  12. Photoperiodic variation in CD45-positive cells and cell proliferation in the mediobasal hypothalamus of the Soay sheep.

    Science.gov (United States)

    Hazlerigg, D G; Wyse, C A; Dardente, H; Hanon, E A; Lincoln, G A

    2013-05-01

    The Earth's solar orbit induces annual climatic changes challenging to survival. Many animals have evolved to cope with seasonal variability through compensatory annual changes in their physiology and behavior, which involve innate long-term timing and photoperiodic synchronization to anticipate the environmental seasonal cycles. Here we considered the potential involvement of cyclical histogenesis in seasonal timing mechanisms in the sheep. Adult Soay rams were established in three distinctive seasonal states by controlled photoperiod exposure. A first group, representing the condition in late spring (long-photoperiod [LP] group), was taken indoors in May and exposed to 4 wks of 16 h light/day (LP). A second group was exposed to 20 wks of LP to establish a late-summer/long-day refractory condition (LPR group). A third group of animals was brought indoors in August and exposed to 4 wks of LP followed by 4 wks of 8 h light/day (short photoperiod [SP]) to establish an autumn-like condition (SP group). At the end of these regimes, we injected 5-bromo-2-deoxyuridine (BrdU), and animals were killed 24 h or 4 wks later. When BrdU was administered 24 h before death, more BrdU-immunopositive cells were detected in the hilus of the hippocampus in LP compared with SP animals, indicative of a higher proliferation rate. When BrdU was administered 4 wks before death, more BrdU-positive cells were detected in the hippocampus under LP, compared with SP, indicating increased cell survival. These mitotic cells were occasionally seen to adopt a neuronal phenotype in the hippocampus, but not in the hypothalamus. Approximately 10% of BrdU-positive cells in the basal hypothalamus coexpressed the pan-leukocytic marker CD45, and showed morphological features and regional distribution consistent with ameboid microglia. Increased numbers of these cells were detected in the region of the median eminence and tuberoinfundibular sulcus of animals kept in SP compared with LP or LPR. These data

  13. Photoperiodic influences on ultradian rhythms of male Siberian hamsters.

    Science.gov (United States)

    Prendergast, Brian J; Zucker, Irving

    2012-01-01

    Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ'), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ' of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L-13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters.

  14. Photoperiodic influences on ultradian rhythms of male Siberian hamsters.

    Directory of Open Access Journals (Sweden)

    Brian J Prendergast

    Full Text Available Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ', amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders, τ' of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L-13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters.

  15. Arabidopsis MSI1 functions in photoperiodic flowering time control.

    Science.gov (United States)

    Steinbach, Yvonne; Hennig, Lars

    2014-01-01

    Appropriate timing of flowering is crucial for crop yield and the reproductive success of plants. Flowering can be induced by a number of molecular pathways that respond to internal and external signals such as photoperiod, vernalization or light quality, ambient temperature and biotic as well as abiotic stresses. The key florigenic signal FLOWERING LOCUS T (FT) is regulated by several flowering activators, such as CONSTANS (CO), and repressors, such as FLOWERING LOCUS C (FLC). Chromatin modifications are essential for regulated gene expression, which often involves the well conserved MULTICOPY SUPRESSOR OF IRA 1 (MSI1)-like protein family. MSI1-like proteins are ubiquitous partners of various complexes, such as POLYCOMB REPRESSIVE COMPLEX2 or CHROMATIN ASSEMBLY FACTOR 1. In Arabidopsis, one of the functions of MSI1 is to control the switch to flowering. Arabidopsis MSI1 is needed for the correct expression of the floral integrator gene SUPPRESSOR OF CO 1 (SOC1). Here, we show that the histone-binding protein MSI1 acts in the photoperiod pathway to regulate normal expression of CO in long day (LD) photoperiods. Reduced expression of CO in msi1-mutants leads to failure of FT and SOC1 activation and to delayed flowering. MSI1 is needed for normal sensitivity of Arabidopsis to photoperiod, because msi1-mutants responded less than wild type to an intermittent LD treatment of plants grown in short days. Finally, genetic analysis demonstrated that MSI1 acts upstream of the CO-FT pathway to enable an efficient photoperiodic response and to induce flowering.

  16. Duração do aleitamento materno, regime alimentar e fatores associados segundo condições de vida em Salvador, Bahia, Brasil Breastfeeding duration, infant feeding regimes, and factors related to living conditions in the city of Salvador, Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Lucivalda P. Magalhães de Oliveira

    2005-10-01

    Full Text Available Este trabalho tem como objetivo conhecer a duração do aleitamento materno, regime alimentar e fatores associados segundo condições de vida em Salvador, Bahia, Brasil. Este estudo de prevalência envolve 811 crianças menores de 24 meses. Para analisar os dados utilizou-se análise de sobrevivência, qui-quadrado de Pearson e regressão logística. A duração mediana do aleitamento exclusivo, predominante e total foi de 30,6, 73 e 131,5 dias, respectivamente. Identificou-se que 83,3% das crianças tiveram interrupção precoce do aleitamento exclusivo ou predominante. As crianças de famílias com condições de vida consideradas baixas tinham 2,3 vezes mais chances (IC95%: 1,09-5,01 de consumirem alimentos complementares precocemente; essa chance se elevou para 2,5 (IC95%: 1,20-5,34 entre aquelas de famílias com condições de vida muito baixas. A interrupção precoce do aleitamento exclusivo ou predominante associou-se com a maternidade em idade precoce e as precárias condições de vida das crianças e suas famílias. Programas direcionados à promoção da prática adequada do aleitamento materno e adoção da alimentação saudável na infância devem considerar a relevância dos fatores sociais envolvidos no oferecimento precoce de alimentos complementares à criança.This cross-sectional study aimed to identify breastfeeding duration, infant feeding regimes, and factors related to living conditions among 811 children under 24 months of age in Salvador, Bahia, Brazil. Data were statistically analyzed by survival analysis, Pearson's chi-square test, and multivariate logistic regression. Median duration of exclusive, predominant, and total breastfeeding was 30.6, 73.0, and 131.5 days, respectively. Exclusive or predominant breastfeeding was discontinued in 83.6% of the subjects. Children with poor living conditions were 2.3 times more likely (95%CI: 1.09-5.01 to receive early supplementary food, whereas the figure for the very poor

  17. Possible Involvement of Photoperiodic Regulation in Reproductive Endocrine System of Female Olive Flounder Paralichthys olivaceus.

    Science.gov (United States)

    Kim, Hyun Chul; Lee, Chi Hoon; Hur, Sung Pyu; Kim, Byeong Hoon; Park, Jun Young; Lee, Young Don

    2015-03-01

    This study investigated possible involvement of photoperiodic regulation in reproductive endocrine system of female olive flounder. To investigate the influence on brain-pituitary axis in endocrine system by regulating photoperiod, compared expression level of Kisspeptin and sbGnRH mRNA in brain and FSH-β, LH-β and GH mRNA in pituitary before and after spawning. Photoperiod was treated natural photoperiod and long photoperiod (15L:9D) conditions from Aug. 2013 to Jun. 2014. Continuous long photoperiod treatment from Aug. (post-spawning phase) was inhibited gonadal development of female olive flounder. In natural photoperiod group, the Kiss2 expression level a significant declined in Mar. (spawning period). And also, FSH-β, LH-β and GH mRNA expression levels were increasing at this period. However, in long photoperiod group, hypothalamic Kiss2, FSH-β, LH-β and GH mRNA expression levels did not show any significant fluctuation. These results suggest that expression of hypothalamic Kiss2, GtH and GH in the pituitary would change in response to photoperiod and their possible involvement of photoperiodic regulation in reproductive endocrine system of the BPG axis.

  18. Similarities in the circadian clock and photoperiodism in plants.

    Science.gov (United States)

    Song, Young Hun; Ito, Shogo; Imaizumi, Takato

    2010-10-01

    Plants utilize circadian clocks to synchronize their physiological and developmental events with daily and yearly changes in the environment. Recent advances in Arabidopsis research have provided a better understanding of the molecular mechanisms of the circadian clock and photoperiodism. One of the most important questions is whether the mechanisms discovered in Arabidopsis are conserved in other plant species. Through the identification of many Arabidopsis clock gene homologs and the characterization of some gene functions, a strong resemblance between the circadian clocks in plants has been observed. On the contrary, based on our recent increased knowledge of photoperiodic flowering mechanisms in cereals and other plants, the day-length sensing mechanisms appear to have diverged more between long-day plants and short-day plants. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Timing of Photoperiodic Flowering:Light Perception and Circadian Clock

    Institute of Scientific and Technical Information of China (English)

    Yun Zhou; Xiao-Dong Sun; Min Ni

    2007-01-01

    Flowering symbolizes the transition of a plant from vegetative phase to reproductive phase and is controlled by fairly complex and highly coordinated regulatory pathways. Over the last decade, genetic studies in Arabidopsis have aided the discovery of many signaling components involved in these pathways. In this review, we discuss how the timing of flowering is regulated by photoperiod and the involvement of light perception and the circadian clock in this process. The specific regulatory mechanisms on CONSTANS expression and CONSTANS stability by the circadian clock and photoreceptors are described in detail. In addition, the roles of CONSTANS, FLOWERING LOCUS T, and several other light signaling and circadiandependent components in photoperiodic flowering are also highlighted.

  20. Flowering time regulation: photoperiod- and temperature-sensing in leaves.

    Science.gov (United States)

    Song, Young Hun; Ito, Shogo; Imaizumi, Takato

    2013-10-01

    Plants monitor changes in photoperiod and temperature to synchronize their flowering with seasonal changes to maximize fitness. In the Arabidopsis photoperiodic flowering pathway, the circadian clock-regulated components, such as FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 and CONSTANS, both of which have light-controlled functions, are crucial to induce the day-length specific expression of the FLOWERING LOCUS T (FT) gene in leaves. Recent advances indicate that FT transcriptional regulation is central for integrating the information derived from other important internal and external factors, such as developmental age, amount of gibberellic acid, and the ambient temperature. In this review, we describe how these factors interactively regulate the expression of FT, the main component of florigen, in leaves.

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

    Science.gov (United States)

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

    2013-08-01

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

  2. Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters.

    Science.gov (United States)

    Noli, Barbara; Brancia, Carla; Pilleri, Roberta; D'Amato, Filomena; Messana, Irene; Manconi, Barbara; Ebling, Francis J P; Ferri, Gian-Luca; Cocco, Cristina

    2015-01-01

    VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA) coupled with high-performance liquid (HPLC) or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis.

  3. Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters.

    Directory of Open Access Journals (Sweden)

    Barbara Noli

    Full Text Available VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA coupled with high-performance liquid (HPLC or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis.

  4. Vernalization and Photoperiod Genes in Iranian Wheat Cultivars

    Directory of Open Access Journals (Sweden)

    Seyyed Hamid Reza Ramazani

    2016-04-01

    Full Text Available Wheat (Triticum aestivum L. can avoid the deleterious effects of low temperatures by using environmental adaptation strategies such as vernalization requirement and photoperiod reaction. Awareness of the genetic factors influencing growth and flowering patterns is necessary for introducing new varieties to specific environments. We performed morphological and genetic studies of 104 lines and cultivars of Iranian wheat genotypes, including four durum genotypes, obtained from national wheat breeding programmes. We used sequence-tagged site (STS-PCR with specific primers to identify alleles affecting the sensitivity to vernalization and photoperiod response at the Vrn-A1, Vrn-B1, Vrn-D1, Ppd-A1, Ppd-B1, and Ppd-D1 loci. Some morphological traits such as percentage germination, growth habit, final leaf number (FLN, ear length, and days to ear emergence were also measured. Results showed that FLN and days to ear emergence are the best morphological traits to study wheat flowering time. Allelic variation showed that Vrn-D1 is more frequent than other genes in Iranian wheat genotypes, and so most Iranian genotypes are vernalization-insensitive. In addition, most genotypes were photoperiod-insensitive because of the semi-dominant mutation allele, Ppd-D1a. Based on allelic variation and morphological traits, we identified five classes of Iranian genotypes. The allelic variation study and morphology evaluation of this germplasm showed that the majority of Iranian cultivars and breeding lines are spring varieties and insensitive to day length.

  5. Temperature and photoperiod as environmental cues affect body mass and thermoregulation in Chinese bulbuls, Pycnonotus sinensis.

    Science.gov (United States)

    Hu, Shi-Nan; Zhu, Ying-Yang; Lin, Lin; Zheng, Wei-Hong; Liu, Jin-Song

    2017-03-01

    Seasonal changes in temperature and photoperiod are important environmental cues used by small birds to adjust their body mass (Mb) and thermogenesis. However, the relative importance of these cues with respect to seasonal adjustments in Mb and thermogenesis is difficult to distinguish. In particular, the effects of temperature and photoperiod on energy metabolism and thermoregulation are not well known in many passerines. To address this problem, we measured the effects of temperature and photoperiod on Mb, energy intake, resting metabolic rate (RMR), organ mass and physiological and biochemical markers of metabolic activity in the Chinese bulbul (Pycnonotus sinensis). Groups of Chinese bulbuls were acclimated in a laboratory to the following conditions: (1) warm and long photoperiod, (2) warm and short photoperiod, (3) cold and long photoperiod, and (4) cold and short photoperiod, for 4 weeks. The results indicate that Chinese bulbuls exhibit adaptive physiological regulation when exposed to different temperatures and photoperiods. Mb, RMR, gross energy intake and digestible energy intake were higher in cold-acclimated than in warm-acclimated bulbuls, and in the short photoperiod than in the long photoperiod. The resultant flexibility in energy intake and RMR allows Chinese bulbuls exposed to different temperatures and photoperiods to adjust their energy balance and thermogenesis accordingly. Cold-acclimated birds had heightened state-4 respiration and cytochrome c oxidase activity in their liver and muscle tissue compared with warm-acclimated birds indicating the cellular mechanisms underlying their adaptive thermogenesis. Temperature appears to be a primary cue for adjusting energy budget and thermogenic ability in Chinese bulbuls; photoperiod appears to intensify temperature-induced changes in energy metabolism and thermoregulation. © 2017. Published by The Company of Biologists Ltd.

  6. Desempenho larval do camarão-d'água-doce (Macrobrachium rosenbergii De Man, 1879) submetido a diferentes regimes alimentares Larval performance of the freshwater prawn (Macrobrachium rosenbergii De Man, 1879) submitted to different feeding systems

    OpenAIRE

    Luciana Almada Thomaz; Lídia Miyako Yoshii Oshiro; Andrea Cecchetto Bambozzi; José Teixeira de Seixas Filho

    2004-01-01

    O desempenho das larvas de Macrobrachium rosenbergii submetidas a quatro diferentes regimes alimentares foi verificado utilizando a observação diária dos subestádios larvais e as primeiras metamorfoses. As larvas foram estocadas em densidade de aproximadamente 100 larvas.l-1, em 16 tanques retangulares, com capacidade de 33 litros. O experimento foi dividido em quatro unidades experimentais (blocos), nos quais foram testados quatro regimes alimentares na larvicultura em circuito aberto, com q...

  7. Photoperiodic Regulation of the Seasonal Pattern of Photosynthetic Capacity and the Implications for Carbon Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Bauerle, William L. [Colorado State University, Fort Collins; Oren, Ram [Duke University; Way, Danielle A. [Duke University; Qian, Song S. [Duke University; Stoy, Paul C. [Montana State University; Thornton, Peter E [ORNL; Bowden, Joseph D. [Colorado State University, Fort Collins; Hoffman, Forrest M [ORNL; Reynolds, Robert F. [Clemson University

    2012-01-01

    Although temperature is an important driver of seasonal changes in photosynthetic physiology, photoperiod also regulates leaf activity. Climate change will extend growing seasons if temperature cues predominate, but photoperiod-controlled species will show limited responsiveness to warming. We show that photoperiod explains more seasonal variation in photosynthetic activity across 23 tree species than temperature. Although leaves remain green, photosynthetic capacity peaks just after summer solstice and declines with decreasing photoperiod, before air temperatures peak. In support of these findings, saplings grown at constant temperature but exposed to an extended photoperiod maintained high photosynthetic capacity, but photosynthetic activity declined in saplings experiencing a naturally shortening photoperiod; leaves remained equally green in both treatments. Incorporating a photoperiodic correction of photosynthetic physiology into a global-scale terrestrial carbon-cycle model significantly improves predictions of seasonal atmospheric CO{sub 2} cycling, demonstrating the benefit of such a function in coupled climate system models. Accounting for photoperiod-induced seasonality in photosynthetic parameters reduces modeled global gross primary production 2.5% ({approx}4 PgC y{sup -1}), resulting in a >3% ({approx}2 PgC y{sup -1}) decrease of net primary production. Such a correction is also needed in models estimating current carbon uptake based on remotely sensed greenness. Photoperiod-associated declines in photosynthetic capacity could limit autumn carbon gain in forests, even if warming delays leaf senescence.

  8. Photoperiodic regulation of the seasonal pattern of photosynthetic capacity and the implications for carbon cycling.

    Science.gov (United States)

    Bauerle, William L; Oren, Ram; Way, Danielle A; Qian, Song S; Stoy, Paul C; Thornton, Peter E; Bowden, Joseph D; Hoffman, Forrest M; Reynolds, Robert F

    2012-05-29

    Although temperature is an important driver of seasonal changes in photosynthetic physiology, photoperiod also regulates leaf activity. Climate change will extend growing seasons if temperature cues predominate, but photoperiod-controlled species will show limited responsiveness to warming. We show that photoperiod explains more seasonal variation in photosynthetic activity across 23 tree species than temperature. Although leaves remain green, photosynthetic capacity peaks just after summer solstice and declines with decreasing photoperiod, before air temperatures peak. In support of these findings, saplings grown at constant temperature but exposed to an extended photoperiod maintained high photosynthetic capacity, but photosynthetic activity declined in saplings experiencing a naturally shortening photoperiod; leaves remained equally green in both treatments. Incorporating a photoperiodic correction of photosynthetic physiology into a global-scale terrestrial carbon-cycle model significantly improves predictions of seasonal atmospheric CO(2) cycling, demonstrating the benefit of such a function in coupled climate system models. Accounting for photoperiod-induced seasonality in photosynthetic parameters reduces modeled global gross primary production 2.5% (∼4 PgC y(-1)), resulting in a >3% (∼2 PgC y(-1)) decrease of net primary production. Such a correction is also needed in models estimating current carbon uptake based on remotely sensed greenness. Photoperiod-associated declines in photosynthetic capacity could limit autumn carbon gain in forests, even if warming delays leaf senescence.

  9. Early regulation of hypothalamic arcuate nucleus CART gene expression by short photoperiod in the Siberian hamster.

    Science.gov (United States)

    Mercer, Julian G; Ellis, Claire; Moar, Kim M; Logie, Tracy J; Morgan, Peter J; Adam, Clare L

    2003-03-28

    Cocaine- and amphetamine-regulated transcript (CART) mRNA is expressed in a number of hypothalamic nuclei including the arcuate nucleus (ARC). An increase in CART gene expression in the ARC of juvenile female Siberian hamsters (Phodopus sungorus) 14 days after transfer to short photoperiod at weaning and prior to major divergence of body weight trajectory in this seasonal mammal implicates CART in the induction of programmed weight change. In the current series of experiments, elevated CART mRNA in short photoperiod juvenile female animals relative to long photoperiod controls was apparent throughout the caudal-rostral extent of the ARC after 14 days, but was not observed when short photoperiod exposure was limited to 4-7 days. Elevated CART gene expression was also observed in juvenile males 14 days after transfer to short photoperiod at weaning, in adult female hamsters 14 days after transfer to short photoperiod and in adult male hamsters 21 days after transfer to short photoperiod. There were no consistent trends in expression levels of other energy balance-related genes with these relatively short duration photoperiod manipulations, suggesting that CART may be involved in short photoperiod-programmed body weight regulation.

  10. Reproductive seasonality in captive wild ruminants: implications for biogeographical adaptation, photoperiodic control, and life history.

    Science.gov (United States)

    Zerbe, Philipp; Clauss, Marcus; Codron, Daryl; Bingaman Lackey, Laurie; Rensch, Eberhard; Streich, Jürgen W; Hatt, Jean-Michel; Müller, Dennis W H

    2012-11-01

    Many ruminant species show seasonal patterns of reproduction. Causes for this are widely debated, and include adaptations to seasonal availability of resources (with cues either from body condition in more tropical, or from photoperiodism in higher latitude habitats) and/or defence strategies against predators. Conclusions so far are limited to datasets with less than 30 species. Here, we use a dataset on 110 wild ruminant species kept in captivity in temperate-zone zoos to describe their reproductive patterns quantitatively [determining the birth peak breadth (BPB) as the number of days in which 80% of all births occur]; then we link this pattern to various biological characteristics [latitude of origin, mother-young-relationship (hider/follower), proportion of grass in the natural diet (grazer/browser), sexual size dimorphism/mating system], and compare it with reports for free-ranging animals. When comparing taxonomic subgroups, variance in BPB is highly correlated to the minimum, but not the maximum BPB, suggesting that a high BPB (i.e. an aseasonal reproductive pattern) is the plesiomorphic character in ruminants. Globally, latitude of natural origin is highly correlated to the BPB observed in captivity, supporting an overruling impact of photoperiodism on ruminant reproduction. Feeding type has no additional influence; the hider/follower dichotomy, associated with the anti-predator strategy of 'swamping', has additional influence in the subset of African species only. Sexual size dimorphism and mating system are marginally associated with the BPB, potentially indicating a facilitation of polygamy under seasonal conditions. The difference in the calculated Julian date of conception between captive populations and that reported for free-ranging ones corresponds to the one expected if absolute day length was the main trigger in highly seasonal species: calculated day length at the time of conception between free-ranging and captive populations followed a y = x

  11. Research update: Yield and nutritive value of photoperiod-sensitive sorghum and sorghum-sudangrass

    Science.gov (United States)

    The objective of this study was to evaluate the yield of photoperiod-sensitive forage sorghum and sorghum-sudangrass against non-photoperiod-sensitive sorghum, sorghum-sudangrass, or corn silage. Forages were planted on two dates at two locations (Marshfield and Hancock, WI). Results suggested some ...

  12. Photoperiodic regulation of testis function in rats: mediation by a circadian mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, R.J.; Bamat, M.K.; Zucker, I.

    1982-05-01

    Laboratory rats traditionally are classified as nonphotoperiodic because variations in daylength have little or no effect on their gonadal function. After olfactory bulbectomy, however, rats show clear evidence of photoperiodic regulation of the gonads. The present study demonstrates, by means of resonance experiments, that the testicular response to daylength in rats is mediated by a circadian photoperiodic time measurement system similar to that of photoperiodic rodents. Olfactory-bulbectomized rats were maintained in fixed photoperiods in which a 6 h light period was coupled with dark periods of 18, 30, 42, or 54 h; a fifth group was maintained in a 45L:10D photoperiod. Rats from the 6L:30D, 6L:54D and 14L:10D photoperiods had testes and seminal vesicle weights, plasma testosterone titers and spermatogenesis indices indicative of functional reproductive status. Rats exposed to the 6L:18D and 6L:42D photoperiods had reduced testicular and seminal vesicle weights, lower testosterone levels and reduced spermatogenesis. Researchers hypothesize that photo- and nonphotoperiodic rodent species use similar mechanisms for distinguishing long from short photoperiods, but differ in the extent to which discrimination of short daylengths is transduced into altered gonadal activity.

  13. Circadian rhythms in the growth and reproduction of the brown alga Undaria pinnatifida and gametogenesis under different photoperiods

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhihuai; PANG Shaojun

    2007-01-01

    Circadian growth rhythm of the juvenile sporophyte of the brown alga Undaria pinnatifida was measured with the computer-aided image analysis system in constant florescent white light under constant temperature ( 10 ℃ ). The growth rhythm persisted for 4 d in constant light with a free-running period of 25.6 h. Egg release from filamentous gametophytes pre-cultured in the light - dark regime was evaluated for six consecutive days at fixed time intervals in constant white light and 12 h light per day. Egg release rhythm persisted for 3 d in both regimes, indicating the endogenous nature. Temporal scale of egg release and gametogenesis in 18, 16, 12 and 8 h light per day were evaluated respectively using vegetatively propagated filamentous gametophytes. Egg release occurred 2 h after the onset of dark phase and peaked at midnight. Evaluation of the rates of oogonium formation, egg release or fertilization revealed no significant differences in four light-dark regimes, indicating the great plasticity of sexual reproduction. No photoperiodic effect in gametogenesis in terms of oogonium formation and egg release was found, but fertilization in short days was significantly higher than in long days. Results of this investigation further confirmed the general occurrence of circadian rhythms in intertidal seaweed species.

  14. Effect of Different Photoperiods on Cold Hardiness in Cherry

    Directory of Open Access Journals (Sweden)

    A.Z. Makaraci

    2009-01-01

    Full Text Available In this research we have investigated the effects of different photoperiods on cold hardiness of cherry trees (Prunus avium cv. Ulster. One year old, cherry trees were exposed 8 hours of day length and 16 hours of dark period for short day conditions and 16 hours of light and 8 hours of dark period for long day conditions. We also compared the acclimatization pattern of cherry trees with hybrid aspen (Populus tremula ×Populus tremuloides trees. LT50 values indicated that short day and long day conditions did not alter the cold hardiness of cherry trees. Under the same experimental conditions hybrid aspen trees were affected from different photoperiods. Aspen trees exposed to short day conditions were hardier than the trees exposed to long day conditions. We also investigated the acclimatization the patterns of basal and apical parts of the branches both in cherry and aspen trees. There were no significant differences in cold hardiness of the basal and apical parts of the branches in aspen and cherry trees.

  15. Integration of light signaling with photoperiodic flowering and circadian rhythm

    Institute of Scientific and Technical Information of China (English)

    Min NI

    2005-01-01

    Plants become photosynthetic through de-etiolation, a developmental process regulated by red/far-red light-absorbing phytochromes and blue/ultraviolet A light-absorbing cryptochromes. Genetic screens have identified in the last decade many far-red light signaling mutants and several red and blue light signaling mutants, suggesting the existence of distinct red, far-red, or blue light signaling pathways downstream of phytochromes and cryptochromes. However, genetic screens have also identified mutants with defective de-etiolation responses under multiple wavelengths. Thus, the optimal de-etiolation responses of a plant depend on coordination among the different light signaling pathways. This review intends to discuss several recently identified signaling components that have a potential role to integrate red, far-red, and blue light signalings. This review also highlights the recent discoveries on proteolytic degradation in the desensitization of light signal transmission, and the tight connection of light signaling with photoperiodic flowering and circadian rhythm. Studies on the controlling mechanisms of de-etiolation, photoperiodic flowering, and circadian rhythm have been the fascinating topics in Arabidopsis research. The knowledge obtained from Arabidopsis can be readily applied to food crops and ornamental species, and can be contributed to our general understanding of signal perception and transduction in all organisms.

  16. Ancestral TSH mechanism signals summer in a photoperiodic mammal.

    Science.gov (United States)

    Hanon, Elodie A; Lincoln, Gerald A; Fustin, Jean-Michel; Dardente, Hugues; Masson-Pévet, Mireille; Morgan, Peter J; Hazlerigg, David G

    2008-08-05

    In mammals, day-length-sensitive (photoperiodic) seasonal breeding cycles depend on the pineal hormone melatonin, which modulates secretion of reproductive hormones by the anterior pituitary gland [1]. It is thought that melatonin acts in the hypothalamus to control reproduction through the release of neurosecretory signals into the pituitary portal blood supply, where they act on pituitary endocrine cells [2]. Contrastingly, we show here that during the reproductive response of Soay sheep exposed to summer day lengths, the reverse applies: Melatonin acts directly on anterior-pituitary cells, and these then relay the photoperiodic message back into the hypothalamus to control neuroendocrine output. The switch to long days causes melatonin-responsive cells in the pars tuberalis (PT) of the anterior pituitary to increase production of thyrotrophin (TSH). This acts locally on TSH-receptor-expressing cells in the adjacent mediobasal hypothalamus, leading to increased expression of type II thyroid hormone deiodinase (DIO2). DIO2 initiates the summer response by increasing hypothalamic tri-iodothyronine (T3) levels. These data and recent findings in quail [3] indicate that the TSH-expressing cells of the PT play an ancestral role in seasonal reproductive control in vertebrates. In mammals this provides the missing link between the pineal melatonin signal and thyroid-dependent seasonal biology.

  17. Reduced body mass, food intake, and testis size in response to short photoperiod in adult F344 rats

    Directory of Open Access Journals (Sweden)

    Heideman Paul D

    2002-07-01

    Full Text Available Abstract Background Although laboratory rats are often considered classic nonseasonal breeders, peripubertal rats of two inbred strains, F344 and BN, have both reproductive and nonreproductive responses to short photoperiods. Unmanipulated adult rats have not been reported to have robust responses to short photoperiod alone, although several treatments can induce photoperiodic responses in adults. In this study, we tested the hypotheses that unmanipulated F344 rats retain responses to short photoperiod as adults and that they have the necessary elements for an endogenous circannual rhythm of sensitivity to short photoperiod. Results Relative to rats kept in long photoperiods (L16:D8, adult F344 rats transferred at 4.5 months of age to short photoperiods (L8:D16 had significantly lower testis size, food intake, and body weight. In a second experiment, newly weaned F344 rats underwent an initial period of inhibition of reproductive maturation, lower food intake, and lower body weight in short photoperiod or intermediate photoperiod (L12:D12 relative to rats in long photoperiod. By 18 weeks of treatment, rats in the two inhibitory photoperiods no longer differed from long photoperiod controls. In short photoperiod, rats underwent a second period of slight reproductive inhibition between weeks 35 and 48, but there was an effect on body weight and slight inhibition of food intake only in an intermediate photoperiod. Conclusion Male F344 rats retain photoresponsiveness as adults, with less reproductive inhibition but equivalent nonreproductive responses. There was only weak evidence for an endogenous timer controlling a circannual cycle of sensitivity to short photoperiod.

  18. Sustainable urban regime adjustments

    DEFF Research Database (Denmark)

    Quitzau, Maj-Britt; Jensen, Jens Stissing; Elle, Morten

    2013-01-01

    The endogenous agency that urban governments increasingly portray by making conscious and planned efforts to adjust the regimes they operate within is currently not well captured in transition studies. There is a need to acknowledge the ambiguity of regime enactment at the urban scale. This directs...... attention to the transformative implications of conscious strategic maneuvering by incumbent regime actors, when confronting regime structurations. This article provides insight to processes of regime enactment performed by local governments by applying a flow-oriented perspective on regime dynamics...

  19. DAILY DYNAMICS OF THE ELEMENTS OF MULE DUCKS BEHAVIOR AT A DIFFERENT AGE, BRED IN INTEGRATED FISH PONDS UNDER DIFFERENT NUTRIENT REGIMES. II. AT APPLYING THE SCHEME OF FEEDING WITH PARTIAL RESTRICTION.

    Directory of Open Access Journals (Sweden)

    Lyudmila NIKOLOVA

    2010-12-01

    Full Text Available An investigation upon the daily dynamics of the separate elements of mule ducks behavior has been carried out at the Institute of Fisheries and Acuaculture Plovdiv, Bulgaria, applying the schedule of feeding with partial restriction, at conditions of integrated fish-ducks technology. Our investigation has shown that the fishponds have been suitable for mule ducks rearing – the birds have had a good plumage status without demonstrations of cannibalism and aggressiveness. Together with the fattening period advance, ducks have spent less time for feeding and have reacted rather weakly to forage supply; the dry land stay time has been on the account of the fish-pond stay, having in mind that the swimming time has increased, as well as the rest time in the fish-pond together with the advance in age.

  20. Deciphering time measurement: the role of circadian 'clock' genes and formal experimentation in insect photoperiodism.

    Science.gov (United States)

    Saunders, D S; Bertossa, R C

    2011-05-01

    This review examines possible role(s) of circadian 'clock' genes in insect photoperiodism against a background of many decades of formal experimentation and model building. Since ovarian diapause in the genetic model organism Drosophila melanogaster has proved to be weak and variable, recent attention has been directed to species with more robust photoperiodic responses. However, no obvious consensus on the problem of time measurement in insect photoperiodism has yet to emerge and a variety of mechanisms are indicated. In some species, expression patterns of clock genes and formal experiments based on the canonical properties of the circadian system have suggested that a damped oscillator version of Pittendrigh's external coincidence model is appropriate to explain the measurement of seasonal changes in night length. In other species extreme dampening of constituent oscillators may give rise to apparently hourglass-like photoperiodic responses, and in still others there is evidence for dual oscillator (dawn and dusk) photoperiodic mechanisms of the internal coincidence type. Although the exact role of circadian rhythmicity and of clock genes in photoperiodism is yet to be settled, Bünning's general hypothesis (Bünning, 1936) remains the most persuasive unifying principle. Observed differences between photoperiodic clocks may be reflections of underlying differences in the clock genes in their circadian feedback loops. Copyright © 2011. Published by Elsevier Ltd.

  1. Effects of the Nordic photoperiod on ozone sensitivity and repair in different clover species studied using infrared imaging.

    Science.gov (United States)

    Futsaether, Cecilia M; Vollsnes, Ane V; Kruse, Ole Mathis Opstad; Otterholt, Eli; Kvaal, Knut; Eriksen, Aud B

    2009-12-01

    Plants in Nordic regions can be more ozone sensitive at a given ozone concentration than plants at lower latitudes. A recent study shows that the Nordic summer photoperiod, particularly the dim nighttime light, can increase visible foliar injury and alter leaf transpiration in subterranean clover. Effects of photoperiod on the ozone sensitivity of white and red clover cultivars adapted to Nordic conditions were investigated. Although ozone induced visible foliar injury and leaf transpirational changes in white clover, the effects were independent of photoperiod. In red clover, ozone combined with a long photoperiod with dim nights (8 nights) induced more severe visible injuries than with a short photoperiod. Furthermore, transpirational changes in red clover depended on photoperiod. Thus, a long photoperiod can increase ozone sensitivity differently in clover cultivars with different degrees of adaptation to northern conditions, suggesting that ozone indices used in risk analysis should take this effect into account.

  2. Identifying yield-optimizing environments for two cowpea breeding lines by manipulating photoperiod and harvest scenario.

    Science.gov (United States)

    Ohler, T A; Mitchell, C A

    1996-05-01

    Photoperiod and harvest scenario of cowpea (Vigna unguiculata L. Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems. Productivity was measured by edible yield rate (EYR:g m-2 day-1), shoot harvest index (SHI: g edible biomass [g total shoot dry weight]), and yield-efficiency rate (YER:g edible biomass m-2 day-1 per[g nonedible shoot dry weight]). Breeding lines 'IT84S-2246' (S-2246) and "IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest). Photoperiod did not affect EYR of either breeding line for any harvest scenario tested. Averaged over both breeding lines, seed harvest gave the highest EYR at 6.7 g m-2 day-1. The highest SHI (65%) and YER (94 mg m-2 day-1 g-1) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario. A second experiment utilized the short-day cowpea breeding line 'IT89KD-288' (D-288) and the day-neutral breeding line 'IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types. This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288.

  3. Identifying yield-optimizing environments for two cowpea breeding lines by manipulating photoperiod and harvest scenario

    Science.gov (United States)

    Ohler, T. A.; Mitchell, C. A.

    1996-01-01

    Photoperiod and harvest scenario of cowpea (Vigna unguiculata L. Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems. Productivity was measured by edible yield rate (EYR:g m-2 day-1), shoot harvest index (SHI: g edible biomass [g total shoot dry weight]), and yield-efficiency rate (YER:g edible biomass m-2 day-1 per[g nonedible shoot dry weight]). Breeding lines 'IT84S-2246' (S-2246) and "IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest). Photoperiod did not affect EYR of either breeding line for any harvest scenario tested. Averaged over both breeding lines, seed harvest gave the highest EYR at 6.7 g m-2 day-1. The highest SHI (65%) and YER (94 mg m-2 day-1 g-1) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario. A second experiment utilized the short-day cowpea breeding line 'IT89KD-288' (D-288) and the day-neutral breeding line 'IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types. This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288.

  4. Photoperiodic growth enhancement in a tropical batch spawning atherinopsid, pike silverside Chirostoma estor.

    Science.gov (United States)

    Martínez-Chávez, C C; Tello-Ballinas, A; Fonseca-Madrigal, J; Ross, L G; Martínez-Palacios, C A

    2014-08-01

    The effect of photoperiod on growth and survival in early life was determined in the tropical batch spawning atherinopsid, pike silverside Chirostoma estor. The results demonstrate high sensitivity of newly hatched C. estor to photoperiod treatments up to 90 days post hatch shown by improved growth in mass (43%) under continuous illumination. This is accompanied by increased fat deposition, which suggests a critical interaction between different photoperiod-mediated mechanisms. A thorough understanding of these mechanisms can help to optimize the development of aquaculture of C. estor and similar species.

  5. Feeding and Breeding Biology of Amblypharyngodon mola – A Review

    Directory of Open Access Journals (Sweden)

    Sandipan Gupta

    2014-05-01

    Full Text Available Amblypharyngodon mola is a popular food fish of Indian sub-continent due to its high nutritional value. Earlier many workers have carried out studies on feeding and breeding biology of this fish species but consolidated information on the same is not available. So, a survey of published literatures on the feeding and breeding biology of A. mola has been carried out to consolidate the available information.  Lacunae of information has been pointed out for further study mainly on age group wise variation in food preference and correlation of breeding periodicity with hydrological parameters and photoperiod.

  6. Temperature regulation in the mouse, Peromyscus leucopus: Effects of various photoperiods, pinealectomy and melatonin administration

    Science.gov (United States)

    Lynch, G. R.; Sullivan, J. K.; Gendler, S. L.

    1980-03-01

    The white-footed mouse, Peromyscus leucopus, exhibits two responses to a decreasing series of photoperiods. The “winter” molt and reproductive regression occur in mice maintained on a photoperiods of 12 hours of light per day or less. Daily torpor and weight of lipid-free brown fat increase gradually between photoperiods of LD 13:11 — LD 12:12 and LD 10:14 — 9:15 LD. Pinealectomized mice maintained on a LD 9:15 photoperiod fail to exhibit the extent of daily torpor and increased nesting which are characteristic of sham-operated animals. Replacement therapy with chronically implanted beeswax pellets containing 3 mg of melatonin reverses the effects of pinealectomy.

  7. Circadian clock genes period and cycle regulate photoperiodic diapause in the bean bug Riptortus pedestris males.

    Science.gov (United States)

    Ikeno, Tomoko; Numata, Hideharu; Goto, Shin G

    2011-07-01

    The photoperiodic response is crucial for many insects to adapt to seasonal changes in temperate regions. It was recently shown that the circadian clock genes period (per) and cycle (cyc) are involved in the photoperiodic regulation of reproductive diapause in the bean bug Riptortus pedestris females. Here, we investigated the involvement of per and cyc both in the circadian rhythm of cuticle deposition and in the photoperiodic diapause of R. pedestris males using RNA interference (RNAi). RNAi of per and cyc disrupted the cuticle deposition rhythm and resulted in distinct cuticle layers. RNAi of per induced development of the male reproductive organs even under diapause-inducing short-day conditions, whereas RNAi of cyc suppressed development of the reproductive organs even under diapause-averting long-day conditions. Thus, the present study suggests that the circadian clock operated by per and cyc governs photoperiodism of males as that of females.

  8. Role of photoperiod on hormone concentrations and adaptive capacity in tree shrews, Tupaia belangeri.

    Science.gov (United States)

    Zhang, Lin; Zhu, Wanlong; Wang, Zhengkun

    2012-11-01

    Environmental factors, such as photoperiod and temperature, play an important role in the regulation of an animal's physiology and behavior. In the present study, we examined the effects of short photoperiod (SD, 8L:16D) on body mass as well as on several physiological, hormonal, and biochemical measures indicative of thermogenic capacity, to test our hypothesis that short photoperiod stimulates increases thermogenic capacity and energy intake in tree shrews. At the end, these tree shrews (SD) had a significant higher body mass, energy intake, cytochrome C oxidase (COX) activity and uncoupling protein-1 (UCP1) content, serum tri-iodothyronine (T(3)) and thyroxine (T(4)) compared to LD (16L:8D) tree shrews. However, there were no significant differences in serum leptin and melatonin between the two groups. Together, these data suggest tree shrews employ a strategy of maximizing body growth and increasing energy intake in response to cues associated with short photoperiod.

  9. PHYTOCHROME C is an essential light receptor for photoperiodic flowering in the temperate grass, Brachypodium distachyon.

    Science.gov (United States)

    Woods, Daniel P; Ream, Thomas S; Minevich, Gregory; Hobert, Oliver; Amasino, Richard M

    2014-09-01

    We show that in the temperate grass, Brachypodium distachyon, PHYTOCHROME C (PHYC), is necessary for photoperiodic flowering. In loss-of-function phyC mutants, flowering is extremely delayed in inductive photoperiods. PHYC was identified as the causative locus by utilizing a mapping by sequencing pipeline (Cloudmap) optimized for identification of induced mutations in Brachypodium. In phyC mutants the expression of Brachypodium homologs of key flowering time genes in the photoperiod pathway such as GIGANTEA (GI), PHOTOPERIOD 1 (PPD1/PRR37), CONSTANS (CO), and florigen/FT are greatly attenuated. PHYC also controls the day-length dependence of leaf size as the effect of day length on leaf size is abolished in phyC mutants. The control of genes upstream of florigen production by PHYC was likely to have been a key feature of the evolution of a long-day flowering response in temperate pooid grasses.

  10. Photoperiodic stress on nitrite production by splenic macrophages in fresh-water snake Natrix piscator

    OpenAIRE

    Tripathi Manish Kumar; Singh Ramesh

    2012-01-01

    Changes in day length enhance or suppress component of immune function in individuals of several species. The purpose of the present experiment was to study the role of photoperiodic manipulation on the nitric oxide production by splenic macrophages in the fresh-water snake, Natrix piscator. To study effect of photoperiod, animals were subjected to 24 hour continuous light and continuous dark for 30 days. Animals kept in natural day length served as control. At termination of experiments, ani...

  11. DAILY DYNAMICS OF THE ELEMENTS OF MULE DUCKS BEHAVIOR AT A DIFFERENT AGE, BRED IN INTEGRATED FISH PONDS UNDER DIFFERENT NUTRIENT REGIMES. I. AT FEEDING WITH BALANCED COMMERCIAL MIXTURE.

    Directory of Open Access Journals (Sweden)

    Lyudmila NIKOLOVA

    2010-12-01

    Full Text Available An investigation upon the daily dynamics of the separate elements of mule ducks behavior has been carried out at the Institute of Fisheries and Acuaculture Plovdiv, Bulgaria, applying the schedule of feeding with full-ration factorymade mixtures, at conditions of integrated fish-ducks technology. Ducks used to enter the water for a short time, and the time for swimming reported has been 9.63 min.h-1 while the time spent at rest in the water has not surpassed 2.5 min.h-1. Age differences concerning behavior have been observed. With the advance of the fattening period, in general, the motion activity has decreased, ducks have reacted weaker to forage supply, and the forages have been consumed more actively during the morning hours. The tested technology has ensured good rearing conditions of mule ducks, however, the influence of ducks upon fishpond ecosystem was minimal.

  12. Timing of puberty and synchronization of seasonal rhythms by simulated natural photoperiods in female Siberian hamsters.

    Science.gov (United States)

    Butler, Matthew P; Trumbull, Justin J; Turner, Kevin W; Zucker, Irving

    2007-07-01

    The timing of puberty is a critical life history trait of short-lived species; spring-born individuals mature rapidly and breed in the season of birth, whereas young born in mid- to late summer delay puberty until the next spring. The cues that govern the transition from rapid to delayed maturation in natural populations remain unknown. To identify ecologically relevant photoperiod cues that control timing of puberty, we monitored nine cohorts of female Siberian hamsters (Phodopus sungorus) born every 2 wk from 4 wk before to 12 wk after the summer solstice in a simulated natural photoperiod (SNP). Hamsters born by the summer solstice underwent rapid somatic growth and achieved puberty that summer; among females born 2-4 wk after the solstice, some delayed puberty by many weeks, whereas others manifested early puberty. Hamsters born 6 or more weeks after the solstice generally delayed puberty until the following spring. The transition from accelerated to delayed pubertal development in the SNP occurred at day lengths that induce early puberty when presented as static photoperiods. Despite differences in timing of birth and timing of puberty, fall and subsequent spring seasonal events occurred at similar calendar dates in all cohorts. We found no evidence that prenatal photoperiod history influenced postnatal development of female hamsters. Considered together with a parallel study on males, the present findings point to sex differences in responsiveness to natural photoperiod variations. In both sexes, incrementally changing photoperiods exert a strong organizing effect on seasonal rhythms.

  13. Photoperiod influences the central effects of ghrelin on food intake, GH and LH secretion in sheep.

    Science.gov (United States)

    Harrison, Joanne L; Miller, David W; Findlay, Patricia A; Adam, Clare L

    2008-01-01

    Ghrelin is a circulating peptide, primarily secreted by the gut, that has reported actions within the hypothalamo-pituitary axis to stimulate food intake, inhibit GnRH/LH secretion and stimulate GH secretion in monogastric species. Here, we examine responses to centrally administered ghrelin in a seasonal ruminant. Estradiol-implanted castrated male sheep with indwelling intracerebroventricular (i.c.v.) cannulae were kept with unrestricted food for 16 weeks in long day photoperiod (LD, 16 h light/day) then 16 weeks in short days (SD, 8 h light/day). In week 16 of each photoperiod they were given a control (saline) i.c.v. injection on day 1 and ghrelin i.c.v. injection on day 2. Mean circulating endogenous plasma ghrelin concentrations showed no diurnal pattern and were similar between the photoperiods. Central ghrelin injection increased voluntary food intake 2-fold in the first hour after administration in LD but not in SD, decreased LH pulse frequency and amplitude in SD but not in LD, and stimulated GH release in both photoperiods, although there was a 1.5-fold larger response in LD. Therefore, central injection of ghrelin to sheep acutely stimulated food intake in LD, suppressed reproductive neuroendocrine output in SD, and stimulated GH secretion irrespective of photoperiod, although more pronounced in LD. These data indicate that photoperiod can influence hypothalamic appetite and reproductive neuroendocrine responses to ghrelin in seasonal species.

  14. Effects of photoperiod on somatic growth and gonadal development in male nile tilapia

    Directory of Open Access Journals (Sweden)

    Rodrigo Diana Navarro

    2015-10-01

    Full Text Available Rotation and translation of the Earth subject the living organisms to cyclic changes of environmental factors. This study evaluated the effects of photoperiod on growth and gonadal development in Nile tilapia (Oreochromis niloticus. In a completely randomized design experiment, juvenile males were distributed into nine tanks (10 fish per tank and maintained for 60 days under three different light treatments with three repetitions each. The treatments were: T1 - 0 h photoperiod (tanks covered with lids and black plastic; T2 - 12 hours photoperiod (tanks uncovered during photoperiod to provide natural light; and T3 - 24 hours photoperiod (tanks covered with lids equipped with lamps. No significant differences were found between treatments for body length, gonad weight or gonadosomatic index, but body weight was higher in fish subjected to T3 compared with other treatments. Furthermore, significant increases in tubular lumen and germinal epithelium were observed in fish exposed to T1 and T3, respectively. Thus, the manipulation of photoperiod in Nile tilapia culture systems can improve production and consequently increase the economic return on investment.

  15. Coordination of Plastid and Light Signaling Pathways upon Development of Arabidopsis Leaves under Various Photoperiods

    Institute of Scientific and Technical Information of China (English)

    Anna Lepist(o); Eevi Rintam(a)ki

    2012-01-01

    Plants synchronize their cellular and physiological functions according to the photoperiod(the length of the light period)in the cycle of 24 h.Photoperiod adjusts several traits in the plant life cycle,including flowering and senescence in annuals and seasonal growth cessation in perennials.Photoperiodic development is controlled by the coordinated action of photoreceptors and the circadian clock.During the past 10 years,remarkable progress has been made in understanding the molecular mechanism of the circadian clock,especially with regard to the transition of Arabidopsis from the vegetative growth to the reproductive phase.Besides flowering photoperiod also modifies plant photosynthetic structures and traits.Light signals controlling biogenesis of chloroplasts and development of leaf photosynthetic structures are perceived both by photoreceptors and in chloroplasts.In this review,we provide evidence suggesting that the photoperiodic development of Arabidopsis leaves mimics the acclimation of plant to various light intensities.Furthermore,the chloroplast-to-nucleus retrograde signals that adjust acclimation to light intensity are proposed to contribute also to the signaling pathways that control photoperiodic acclimation of leaves.

  16. Photoperiod and testosterone regulate androgen receptor immunostaining in the Siberian hamster brain.

    Science.gov (United States)

    Bittman, Eric L; Ehrlich, David A; Ogdahl, Justyne L; Jetton, Amy E

    2003-09-01

    Day length regulates the effects of gonadal steroids on gonadotropin secretion and behavior in seasonal breeders. To determine whether this influence of photoperiod results from changes in androgen receptor expression in Siberian hamster brain regions that regulate neuroendocrine function, androgen receptor immunostaining was examined in castrated animals given either no androgen replacement or one of three doses of testosterone (T) resulting in physiological serum concentrations. Half of the animals were housed under inhibitory photoperiod conditions, and immunostaining was quantified 11 days later. Measurement of serum gonadotropin and prolactin concentrations confirmed that androgen exerted graded effects on pituitary function but that the animals were killed before photoperiodic influences had fully developed. T significantly increased the numbers of androgen receptor-immunoreactive cells in every brain region examined. Photoperiod exerted no significant influence on androgen receptor-immunoreactive cell number in the arcuate nucleus, bed nucleus of the stria terminalis (BNST), medial preoptic nucleus, or in medial amygdala. An interaction between T and photoperiod was observed in the BNST and in the rostral and middle portions of the arcuate nucleus. Although increasing concentrations of T resulted in more intense cellular immunostaining in the BNST and arcuate, this effect was not influenced by day length. These results indicate that relatively short-duration (11 days) exposure to inhibitory photoperiod triggers localized and regionally specific changes in androgen receptor expression.

  17. Beyond Emotional and Spatial Processes: Cognitive Dysfunction in a Depressive Phenotype Produced by Long Photoperiod Exposure.

    Science.gov (United States)

    Barnes, Abigail K; Smith, Summer B; Datta, Subimal

    2017-01-01

    Cognitive dysfunction in depression has recently been given more attention and legitimacy as a core symptom of the disorder. However, animal investigations of depression-related cognitive deficits have generally focused on emotional or spatial memory processing. Additionally, the relationship between the cognitive and affective disturbances that are present in depression remains obscure. Interestingly, sleep disruption is one aspect of depression that can be related both to cognition and affect, and may serve as a link between the two. Previous studies have correlated sleep disruption with negative mood and impaired cognition. The present study investigated whether a long photoperiod-induced depressive phenotype showed cognitive deficits, as measured by novel object recognition, and displayed a cognitive vulnerability to an acute period of total sleep deprivation. Adult male Wistar rats were subjected to a long photoperiod (21L:3D) or a normal photoperiod (12L:12D) condition. Our results indicate that our long photoperiod exposed animals showed behaviors in the forced swim test consistent with a depressive phenotype, and showed significant deficits in novel object recognition. Three hours of total sleep deprivation, however, did not significantly change novel object recognition in either group, but the trends suggest that the long photoperiod and normal photoperiod groups had different cognitive responses to total sleep deprivation. Collectively, these results underline the extent of cognitive dysfunction present in depression, and suggest that altered sleep plays a role in generating both the affective and cognitive symptoms of depression.

  18. Reproductive performance of the Mesa silverside (Chirostoma jordani Woolman, 1894) under natural and controlled photoperiods.

    Science.gov (United States)

    Arredondo-Figueroa, José Luis; Núñez-García, Laura Georgina; Heredia-Guzmán, Paloma Adriana; Ponce-Palafox, Jesús T

    2012-12-01

    Chirostoma jordani is a native annual species inhabiting lacustrine waters of the Central Mexico Plateau. It is widely distributed and is currently facing high environmental pressures. Five experiments were performed to study the reproductive performance of this species. Four of the experiments were conducted in 270-L indoor recirculation tanks. Two males and one female at the first stage of reproduction were included in each test. A photoperiod of 14 light hours and 10 dark hours was used. In a fifth experiment, 10 females and 15 males were kept in an outdoor 3,000-L recirculation tank under natural photoperiod. The number of spawns, fertilised eggs and 30-day-old juveniles were counted and the survival rate was calculated. The results indicated significant differences (P < 0.05) between treatments. Higher spawn numbers and greater egg production were observed under controlled photoperiod, and higher numbers of juveniles and a higher survival rate were observed under natural photoperiod. The trials exhibited different patterns of egg production during the experiment. The egg production in the natural-photoperiod trials followed a polynomial curve model. In contrast, the trials under the controlled photoperiod showed an irregular pattern of increases and decreases in egg production.

  19. Differentiation of photoperiod-induced ABA and soluble sugar responses of two quinoa (Chenopodium quinoa willd.) cultivars

    DEFF Research Database (Denmark)

    Bendevis, Mira Arpe; Sun, Yujie; Shabala, Sergey

    2014-01-01

    and Titicaca (day-length neutral), were subjected to continuous long (17.5 h) and short (10 h) photoperiod conditions as well as a shift between the two to trigger possible adaptive mechanisms initiated by changes in leaf soluble sugar and ABA concentration. Our findings show both cultivars responding...... to an increase in photoperiod with significant increases in soluble sugar concentrations and a simultaneous increase in ABA. However, Titicaca exhibited a much stronger ABA response to increase in photoperiod, whereas the increase for Achachino falls within the range of natural diurnal variation. Achachino also......-dependent chlorosis of the lower leaves of Titicaca was observed under long photoperiods compared to short photoperiods, implying multi-faceted adaptive responses to changes in photoperiod which may also involve nitrogen and carbon dynamics. Both ABA and sugar signals are possibly involved in regulating...

  20. Effect of photoperiod on gibberellin biosynthetic enzymes in spinach

    Energy Technology Data Exchange (ETDEWEB)

    Gilmour, S.J.; Bleecker, A.B.; Zeevaart, J.A.D.

    1986-04-01

    The photoperiodic control of stem elongation in spinach, a long day (LD) rosette plant, is mediated by gibberellins (GAs). The early 13-hydroxylated GA biosynthetic pathway from GA/sub 12/ to GA/sub 20/ operates in spinach: GA/sub 12/ ..-->.. GA/sub 53/ ..-->.. GA/sub 44/ ..-->.. GA/sub 19/ ..-->.. GA/sub 20/. Two enzymes of this pathway, those converting GA/sub 53/ to GA/sub 44/ (GA/sub 53/ oxidase) and GA/sub 19/ to GA/sub 20/ (GA/sub 19/ oxidase), are regulated by light. The enzyme converting GA/sub 44/ to GA/sub 19/ (GA/sub 44/ oxidase) is not light-regulated. In the light GA/sub 53/ and GA/sub 18/ oxidase activities are increased, therefore causing the GA biosynthetic pathway to be turned on. This leads to the production of an active GA in LD, which causes an increase in stem elongation. Two the enzymes, GA/sub 44/ and GA/sub 53/ oxidases, can be separated from one another by anion exchange HPLC. Estimates of the molecular weights of these two enzymes based on gel filtration HPLC will be reported.

  1. Simulation of oat development cycle by photoperiod and temperature

    Directory of Open Access Journals (Sweden)

    Rubia D. Mantai

    Full Text Available ABSTRACT The simulation of oat development cycle can be used in the planning of agricultural practices. The aim of the study was to simulate and validate the duration of oat development cycle by photoperiod, temperature and coefficients of development of wheat for use in the WE-Streck model, considering different doses of N-fertilizer and systems of succession of high and low C/N ratio. The study was conducted in 2015 in a randomized block design with four replicates in a 4 x 2 factorial scheme, corresponding to N rates (0, 30, 60 and 120 kg ha-1 and oat cultivars (Barbarasul and Brisasul, respectively, in the soybean/oat and maize/oat systems. The duration of the stages from emergence to anthesis and from anthesis to maturation of oats was simulated in the WE-Streck model. The minimum, optimum and maximum temperatures that effectively simulate the oat development cycle were 4, 22 and 30 °C from emergence to anthesis and 15, 25 and 35 °C from anthesis to maturation, respectively. The intermediate-cycle oat development was efficiently simulated by the WE-Streck model using coefficients developed for wheat, with vegetative and reproductive cycles estimated at 89 and 43 days, respectively.

  2. Unexpected diversity and photoperiod dependence of the zebrafish melanopsin system.

    Directory of Open Access Journals (Sweden)

    Vanessa Matos-Cruz

    Full Text Available Animals have evolved specialized photoreceptors in the retina and in extraocular tissues that allow them to measure light changes in their environment. In mammals, the retina is the only structure that detects light and relays this information to the brain. The classical photoreceptors, rods and cones, are responsible for vision through activation of rhodopsin and cone opsins. Melanopsin, another photopigment first discovered in Xenopus melanophores (Opn4x, is expressed in a small subset of retinal ganglion cells (RGCs in the mammalian retina, where it mediates non-image forming functions such as circadian photoentrainment and sleep. While mammals have a single melanopsin gene (opn4, zebrafish show remarkable diversity with two opn4x-related and three opn4-related genes expressed in distinct patterns in multiple neuronal cell types of the developing retina, including bipolar interneurons. The intronless opn4.1 gene is transcribed in photoreceptors as well as in horizontal cells and produces functional photopigment. Four genes are also expressed in the zebrafish embryonic brain, but not in the photoreceptive pineal gland. We discovered that photoperiod length influences expression of two of the opn4-related genes in retinal layers involved in signaling light information to RGCs. Moreover, both genes are expressed in a robust diurnal rhythm but with different phases in relation to the light-dark cycle. The results suggest that melanopsin has an expanded role in modulating the retinal circuitry of fish.

  3. Evidence that the circadian system mediates photoperiodic nonresponsiveness in Siberian hamsters: the effect of running wheel access on photoperiodic responsiveness.

    Science.gov (United States)

    Freeman, D A; Goldman, B D

    1997-04-01

    Juvenile male Siberian hamsters from a line of hamsters selected for nonresponsiveness to short photoperiod (PNRj) and animals from the general colony (UNS) were separated at weaning into two groups. Group 1 males were moved into short days (10 h light:14 h dark [10L:14D]) with free access to running wheels (RW). Group 2 animals were the male siblings of Group 1 hamsters; they were moved at the same time into the same room, but were housed in cages without access to RW. Group 2 hamsters only had access to RW for the final week of short-day exposure (Week 8). Animals were blood sampled at the time of sacrifice for analysis of serum prolactin (PRL) and follicle-stimulating hormone (FSH) concentrations. At sacrifice, paired testis weights were obtained and pelage color was scored. Animals from the UNS line showed the expected declines in testis weight, body weight, and serum concentrations of both PRL and FSH, regardless of the presence or absence of RW. These animals also exhibited a high proportion of individuals molting to winter-type pelage. By contrast, a marked difference was noted between siblings from the PNRj line depending on whether RW access was provided at the time of weaning. Animals with access to RW exhibited identical responses to those of the UNS responder animals, whereas PNRj animals without access to RW showed no adjustments to short days (i.e., testis regression, pelage molt, expansion of alpha). In a second experiment, PNRj and UNS males were placed in constant darkness (DD), with or without RW access. The results of this experiment indicated that PNRj animals respond to DD regardless of the presence or absence of RW. In DD, PNRj hamsters also exhibited significantly longer free-running period lengths (taus) than did UNS hamsters; all the PNRj hamsters had taus > 24 h, whereas none of the UNS hamsters had a tau > 24 h. These results indicate that PNRj hamsters retain the proper neural pathways for responding to short day lengths and establish a

  4. Strawberry homologue of terminal flower1 integrates photoperiod and temperature signals to inhibit flowering.

    Science.gov (United States)

    Rantanen, Marja; Kurokura, Takeshi; Jiang, Panpan; Mouhu, Katriina; Hytönen, Timo

    2015-04-01

    Photoperiod and temperature are major environmental signals affecting flowering in plants. Although molecular pathways mediating these signals have been well characterized in the annual model plant Arabidopsis, much less information is known in perennials. Many perennials including the woodland strawberry (Fragaria vesca L.) are induced to flower in response to decreasing photoperiod and temperature in autumn and they flower following spring. We showed earlier that, in contrast with Arabidopsis, the photoperiodic induction of flowering in strawberry occurs in short days (SD) when the decrease in FvFT1 (flowering locus T) and FvSOC1 (suppressor of the overexpression of constans1) expression leads to lower mRNA levels of the floral repressor, FvTFL1 (terminal flower1). By using transgenic lines and gene expression analyses, we show evidence that the temperature-mediated changes in the FvTFL1 mRNA expression set critical temperature limits for the photoperiodic flowering in strawberry. At temperatures below 13 °C, low expression level of FvTFL1 in both SD and long days (LD) allows flower induction to occur independently of the photoperiod. Rising temperature gradually increases FvTFL1 mRNA levels under LD, and at temperatures above 13 °C, SD is required for the flower induction that depends on the deactivation of FvSOC1 and FvTFL1. However, an unknown transcriptional activator, which functions independently of FvSOC1, enhances the expression of FvTFL1 at 23 °C preventing photoperiodic flowering. We suggest that the observed effect of the photoperiod × temperature interaction on FvTFL1 mRNA expression may allow strawberry to induce flowers in correct time in different climates.

  5. The role of induced mutation in conversion of photoperiod dependence in cotton.

    Science.gov (United States)

    Abdurakhmonov, Ibrokhim Y; Kushanov, Fakhriddin N; Djaniqulov, Fayzulla; Buriev, Zabardast T; Pepper, Alan E; Fayzieva, Nilufar; Mavlonov, Gafurjon T; Saha, Sukumar; Jenkins, Jonnie N; Abdukarimov, Abdusattor

    2007-01-01

    Wild cotton germplasm resources are largely underutilized because of photoperiod-dependent flowering of "exotic" cottons. The objectives of this work were to explore the genome-wide effect of induced mutation in photoperiod-converted induced cotton mutants, estimating the genetic change between mutant and wild-type cottons using simple sequence repeats (SSRs) as well as understand the pattern of SSR mutation in induced mutagenesis. Three groups of photoperiod-converted radiomutants ((32)P) including their wild-type parental lines, A- and D-genome diploids, and typically grown cotton cultivars were screened with 250 cotton SSR primer pairs. Forty SSRs revealed the same SSR mutation profile in, at least, 2 independent mutant lines that were different from the original wild types. Induced mutagenesis both increased and decreased the allele sizes of SSRs in mutants with the higher mutation rate in SSRs containing dinucleotide motifs. Genetic distance obtained based on 141 informative SSR alleles ranged from 0.09 to 0.60 in all studied cotton genotypes. Genetic distance within all photoperiod-converted induced mutants was in a 0.09-0.25 range. The genetic distance among photoperiod-converted mutants and their originals ranged from 0.28 to 0.50, revealing significant modification of mutants from their original wild types. Typical Gossypium hirsutum cultivar, Namangan-77, revealed mutational pattern similar to induced radiomutants in 40 mutated SSR loci, implying possible pressure to these SSR loci not only in radiomutagenesis but also during common breeding process. Outcomes of the research should be useful in understanding the photoperiod-related mutations, and markers might help in mapping photoperiodic flowering genes in cotton.

  6. Effect of reverse photoperiod on in vitro regeneration and piperine production in Piper nigrum L.

    Science.gov (United States)

    Ahmad, Nisar; Abbasi, Bilal Haider; Fazal, Hina; Khan, Mubarak Ali; Afridi, Muhammad Siddique

    2014-01-01

    In this study, a novel approach for in vitro regeneration of Piper nigrum L. has been applied in order to increase healthy biomass, phytochemicals and piperine production via reverse photoperiod (16hD/8hL). Leaf portions of the seed-derived plants were placed on an MS-medium fortified with different PGRs. Under 16hD/8hL, thidiazuron (TDZ; 4.0 mg L⁻¹) and BA (1.5 mg L⁻¹) was found to be the most effective (80% shoots from callus cultures. Healthy shoots were transferred to rooting medium and higher percentage of rooting (<90%) was observed on IBA (1.5 mg L⁻¹). These in vitro tissues were subjected to amino acid analysis, spectrophotometry, and HPLC. ARG, SER, THR, and TYR were the most abundant components out of 17 amino acids. Higher amino acid production was observed under normal photoperiod (16hL/8hD) than under reverse photoperiod (16hD/8hL). The highest total phenolic content (TPC; 9.91 mg/g-DW) and flavonoid content (7.38 mg/g-DW) were observed in callus cultures incubated under 16hL/8hD than other tissues incubated under 16hD/8hL photoperiod. Higher DPPH and PoMo activities were observed in tissues incubated under 16hL/8hD photoperiod, while ABTS and Fe²⁺ chelating activities were found higher in tissues incubated under reverse photoperiod. Significant quantities of piperine content were observed in all tissues except callus cultures. These results suggest that reverse photoperiod is a promising approach for callus induction, phytochemicals and piperine production for commercial applications.

  7. Measuring autocratic regime stability

    Directory of Open Access Journals (Sweden)

    Joseph Wright

    2016-01-01

    Full Text Available Researchers measure regime stability in autocratic contexts using a variety of data sources that capture distinct concepts. Often this research uses concepts developed for the study of democratic politics, such as leadership change or institutionalized authority, to construct measures of regime breakdown in non-democratic contexts. This article assesses whether the measure a researcher chooses influences the results they obtain by examining data on executive leadership, political authority, and autocratic regimes. We illustrate the conceptual differences between these variables by extending recent studies in the literature on the political consequences of non-tax revenue and unearned foreign income.

  8. Exchange rate regime choice

    Directory of Open Access Journals (Sweden)

    Beker Emilija

    2006-01-01

    Full Text Available The choice of an adequate exchange rate regime proves to be a highly sensitive field within which the economic authorities present and confirm themselves. The advantages and disadvantages of fixed and flexible exchange rate regimes, which have been quite relativized from the conventional point of view, together with simultaneous, but not synchronized effects of structural and external factors, remain permanently questioned throughout a complex process of exchange rate regime decision making. The paper reflects the attempt of critical identification of the key exchange rate performances with emphasis on continuous non-uniformity and (uncertainty of shelf life of a relevant choice.

  9. Increased photic sensitivity for phase resetting but not melatonin suppression in Siberian hamsters under short photoperiods.

    Science.gov (United States)

    Glickman, G L; Harrison, E M; Elliott, J A; Gorman, M R

    2014-03-01

    Light regulates a variety of behavioral and physiological processes, including activity rhythms and hormone secretory patterns. Seasonal changes in the proportion of light in a day (photoperiod) further modulate those functions. Recently, short (SP) versus long days (LP) were found to markedly increase light sensitivity for phase shifting in Syrian hamsters. To our knowledge, photoperiod effects on light sensitivity have not been studied in other rodents, nor is it known if they generalize to other circadian responses. We tested whether photic phase shifting and melatonin suppression vary in Siberian hamsters maintained under LP or SP. Select irradiances of light were administered, and shifts in activity were determined. Photic sensitivity for melatonin suppression was examined in a separate group of animals via pulses of light across a 4 log-unit photon density range, with post-pulse plasma melatonin levels determined via RIA. Phase shifting and melatonin suppression were greater at higher irradiances for both LP and SP. The lower irradiance condition was below threshold for phase shifts in LP but not SP. Melatonin suppression did not vary by photoperiod, and the half saturation constant for fitted sigmoid curves was similar under LP and SP. Thus, the photoperiodic modulation of light sensitivity for phase shifting is conserved across two hamster genera. The dissociation of photoperiod effects on photic phase shifting and melatonin suppression suggests that the modulation of sensitivity occurs downstream of the common retinal input pathway. Understanding the mechanistic basis for this plasticity may yield therapeutic targets for optimizing light therapy practices.

  10. [Growth and development of cucumber Cucumis sativus L. in the prereproductive period under long photoperiods].

    Science.gov (United States)

    Shibaeva, T G; Markovskaia, E F

    2013-01-01

    When plants are grown in a greenhouse, an increase in the photoperiod, as well as continuous lighting, is one of the ways to improve plant productivity and energy savings. However, a number of crops under long photoperiods develop signs of light damage to leaves, and productivity is reduced. We studied the effect of the photoperiod (8, 12, 16, 20, and 24 h) and photon flux densities (60, 120, and 160 micromol/m2 with PAR) on cucumber plants Cucumis sativus L. in a prereproductive period. We show that the response of the cucumber plants to a photoperiod duration of more than 20 h, including continuous lighting, depending on the plant age and lighting conditions, may include epinastic reaction of the leaves, activation of a mechanism of nonphotochemical chlorophyll fluorescence quenching, and/or reversible photoinhibition of a reaction center of photosystem II, development of reversible chlorosis, reduction of a light-harvesting complex, and increase in the content of carotenoids. Reaction of immature and virginile plants to long photoperiods was different, which highlights the need for experimental separation of the prereproductive period of development in terms of age states and consideration of this when preparing programs of cultivation.

  11. The role of photoperiods on photobioreactors - A potential strategy to reduce costs.

    Science.gov (United States)

    Maroneze, Mariana Manzoni; Siqueira, Stefania Fortes; Vendruscolo, Raquel Guidetti; Wagner, Roger; de Menezes, Cristiano Ragagnin; Zepka, Leila Queiroz; Jacob-Lopes, Eduardo

    2016-11-01

    The aim of this work was evaluate the role of photoperiods (long-term, frequencies and short) on the growth and lipid content of microalgae Scenedesmus obliquus CPCC05. The results showed that Scenedesmus obliquus can store sufficient energy to sustain cell growth for continuous periods of up to 2h in the dark, without affecting the photosynthetic rate. The values for maximum biomass (9.58mg/Lh) and lipid productivities (2.56mg/Lh) were obtained at photoperiod of 0.91:0.09s (light:dark) and 48 t/d, respectively. Moreover, the best trade-offs between biomass productivity and light energy economy occurred in photoperiods of 0.5:0.5s and 0.91:0.09s (light:dark), and those between lipid productivity and light energy economy occurred in the frequency photoperiod of 24 and 48 t/d. Thus, the use of the photoperiods are an effective strategy for reducing costs of microalgal biomass production.

  12. Identification of photoperiod-regulated gene in soybean and functional analysis in Nicotiana benthamiana

    Indian Academy of Sciences (India)

    Sha Ai-Hua; Chen Yin-Hua; Shan Zhi-Hui; Zhang Xiao-Juan; Wu Xue-Jun; Qiu De-Zheng; Zhou Xin-An

    2014-04-01

    Soybean (Glycine max) is a short-day crop and the photoperiod is a crucial factor regulating its flowering time. To investigate the molecular mechanism controlling the flowering time by photoperiod in soybean, cDNA-amplified fragment length polymorphism (cDNA-AFLP) was used to identify photoperiod-regulated genes in leaves of soybean growing under short-day length, neutral photoperiod and long-day length. A total of 36 transcript-derived fragments (TDFs) were identified to be regulated by photoperiod. Among them, 26 TDFs were homologues of genes with known function. These genes are involved in secondary metabolism, cellular metabolism, cell wall components metabolism, ion transport and hormone signalling. Silencing of the homologue genes in Nicotiana benthamiana for 14 TDFs was conducted by virus-induced gene silencing. The flowering time was delayed by silencing of the genes encoding rhodanese and 40S ribosomal protein S4 (RPS4). The results indicated that rhodanese and RPS4 probably play important roles in regulating flowering time.

  13. Circadian clock and photoperiodic response in Arabidopsis: from seasonal flowering to redox homeostasis.

    Science.gov (United States)

    Shim, Jae Sung; Imaizumi, Takato

    2015-01-20

    Many of the developmental responses and behaviors in plants that occur throughout the year are controlled by photoperiod; among these, seasonal flowering is the most characterized. Molecular genetic and biochemical analyses have revealed the mechanisms by which plants sense changes in day length to regulate seasonal flowering. In Arabidopsis thaliana, induction of the expression of a florigen, FLOWERING LOCUS T (FT) protein, is a major output of the photoperiodic flowering pathway. The circadian clock coordinates the expression profiles and activities of the components in this pathway. Light-dependent control of CONSTANS (CO) transcription factor activity is a crucial part of the induction of the photoperiodic expression of FT. CO protein is stabilized only in the long day afternoon, which is when FT is induced. In this review, we summarize recent progress in the determination of the molecular architecture of the circadian clock and mechanisms underlying photoperiodic flowering. In addition, we introduce the molecular mechanisms of other biological processes, such as hypocotyl growth and reactive oxygen species production, which are also controlled by alterations in photoperiod.

  14. [Effects of photoperiod on photosynthesis and PSII performance in peach during dormancy induction].

    Science.gov (United States)

    Li, Dong-Mei; Tan, Qiu-Ping; Gao, Dong-Sheng; Chen, Xiu-De; Li, Ling

    2014-07-01

    Long-day and short-day photoperiods were set artificially, with natural condition as the control, to examine photosynthetic parameters and chlorophyll fluorescence transient kinetics of 6-year-old 'Chunjie' peach cultivar (Prunus persica cv. Chunjie), and to investigate the effects of photoperiod on photosynthesis of the northern deciduous fruit trees. The tree advanced into the dormancy induction period under the short-day condition, and delayed under the long-day condition. In the dormancy induction period, the leaf net photosynthetic rate (Pn) and stomatal conductance (g(s)) decreased, and the intercellular CO2 concentration (Ci) increased, suggesting that the Pn decreased because of non-stomatal limitation. Maximum quantum yield for primary photochemistry (PhiPo, or Fv/Fm), potential activity (Fv/Fo), probability that a trapped exciton moved an electron into the electron transport chain beyond Q(A)-(Psi(o)) and performance index on absorption basis (Pl(ABS)) decreased in the dormancy induction period, suggesting that the electron transport capacity of photosynthetic electron transport chain was inhibited, possibly due to the damage to downstream electron transport chain (after Q(A)- acceptor) of PS II reaction center. Long-day photoperiod improved Pn in the dormancy induction period, and reduced the range of decline in PI(ABS) and the injured degree of photosystem. Short-day photoperiod deepened and accelerated the damage to photosynthetic apparatus significantly. The induced effect of photoperiod was associated with the dormancy processes.

  15. Photoperiodic regulation of FGF21 production in the Siberian hamster.

    Science.gov (United States)

    Samms, Ricardo J; Fowler, Maxine J; Cooper, Scott; Emmerson, Paul; Coskun, Tamer; Adams, Andrew C; Kharitonenkov, Alexei; Tsintzas, Kostas; Ebling, Francis J P

    2014-06-01

    This article is part of a Special Issue "Energy Balance". FGF21 is an endocrine member of the fibroblast growth factor superfamily that has been shown to play an important role in the physiological response to nutrient deprivation. Food restriction enhances hepatic FGF21 production, which serves to engage an integrated response to energy deficit. Specifically, elevated FGF21 levels lead to reduced gluconeogenesis and increased hepatic ketogenesis. However, circulating FGF21 concentrations also paradoxically rise in states of metabolic dysfunction such as obesity. Furthermore, multiple peripheral tissues also produce FGF21 in addition to the liver, raising questions as to its endocrine and paracrine roles in the control of energy metabolism. The objectives of this study were to measure plasma FGF21 concentrations in the Siberian hamster, a rodent which undergoes a seasonal cycle of fattening and body weight gain in the long days (LD) of summer, followed by reduction of appetite and fat catabolism in the short days (SD) of winter. Groups of adult male hamsters were raised in long days, and then exposed to SD for up to 12 weeks. Chronic exposure of LD animals to SD led to a significant increase in circulating FGF21 concentrations. This elevation of circulating FGF21 was preceded by an increase in liver FGF21 protein production evident as early as 4 weeks of exposure to SD. FGF21 protein abundance was also increased significantly in interscapular brown adipose tissue, with a positive correlation between plasma levels of FGF21 and BAT protein abundance throughout the experimental period. Epididymal white adipose tissue and skeletal muscle (gastrocnemius) also produced FGF21, but levels did not change in response to a change in photoperiod. In summary, a natural programmed state of fat catabolism was associated with increased FGF21 production in the liver and BAT, consistent with the view that FGF21 has a role in adapting hamsters to the hypophagic winter state.

  16. Phytochrome controlled, long-day photoperiod-inducible protein in rice leaves

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new protein in the leaves of NK58S and NK58 (Oryza sativa L. subsp. japonica), which can be induced by 10 d-long-day photoperiod (14 h light/d) and cannot be induced by 10 d-short-day photoperiod (10 h light/d), has been found by two-dimensional gel electrophoresis. The protein,whose molecular weight and isoelectric point are 36 ku and pH 5.2 respectively, is found to be controlled by phytochrome as shown by the experiment of red light induction-far red light reversion.The existence of this protein in both NK58S and NK58 reflects that some of the responses of NK58S and NK58 might be similar in response to long-day photoperiod, a mild stress.

  17. Molecular Regulatory Network of Flowering by Photoperiod and Temperature in Rice

    Institute of Scientific and Technical Information of China (English)

    SONG Yuan-li; LUAN Wei-jiang

    2012-01-01

    Plants have an ability to flower under optimal seasonal conditions to ensure reproductive success.Photoperiod and temperature are two important season-dependent factors of plant flowering.The floral transition of plants depends on accurate measurement of changes in photoperiod and temperature.Recent advances in molecular biology and genetics on Arabidopsis and rice reveals that the regulation of plant flowering by photoperiod and temperature are involved in a complicated gene network with different regulatory pathways,and new evidence and understanding were provided in the regulation of rice flowering.Here,we summarize and analyze different flowering regulatory pathways in detail in rice based on previous studies and our results,including short-day promotion,long-day suppression,long-day induction of flowering,night break,different light-quality and temperature regulation pathways.

  18. Effects of photoperiod, growth temperature and cold acclimatisation on glucosinolates, sugars and fatty acids in kale.

    Science.gov (United States)

    Steindal, Anne Linn Hykkerud; Rødven, Rolf; Hansen, Espen; Mølmann, Jørgen

    2015-05-01

    Curly kale is a robust, cold tolerant plant with a high content of health-promoting compounds, grown at a range of latitudes. To assess the effects of temperature, photoperiod and cold acclimatisation on levels of glucosinolates, fatty acids and soluble sugars in kale, an experiment was set up under controlled conditions. Treatments consisted of combinations of the temperatures 15/9 or 21/15 °C, and photoperiods of 12 or 24h, followed by a cold acclimatisation period. Levels of glucosinolates and fatty acid types in leaves were affected by growth conditions and cold acclimatisation, being generally highest before acclimatisation. The effects of growth temperature and photoperiod on freezing tolerance were most pronounced in plants grown without cold acclimatisation. The results indicate that cold acclimatisation can increase the content of soluble sugar and can thereby improve the taste, whilst the content of unsaturated fatty and glucosinolates acids may decrease.

  19. Effect of photoperiod change on chronobiology of cercarial emergence of Schistosoma japonicum derived from hilly and marshy regions of China.

    Science.gov (United States)

    Wang, Su-Rong; Zhu, Yuan-Jian; Ge, Qing-Peng; Yang, Meng-Jia; Huang, Ji-Lei; Huang, Wen-Qiao; Zhuge, Hong-Xiang; Lu, Da-Bing

    2015-12-01

    The chronobiology of cercarial emergence appeared to be a genetically controlled behavior, adapted to definitive host species, for schistosome. However, a few physiological and ecological factors, for example the change of photoperiod, were reported to affect the rhythmic emergence of cercariae. Therefore, the effect of photoperiod change on cercarial emergence of two Schistosoma japonicum isolates, the hilly and the marshland, was investigated. Four shedding experiments each under a different photoperiod were conducted. Under a natural photoperiod, two distinct shedding modes, one from the hilly region and one from the marshland, were observed. Under a reversed photoperiod, the regular pattern (i.e. under a natural photoperiod) of S. japonicum cercarial emergence was reversed for the marshland isolate and disappeared for the hilly isolate. With an input of a 2 h darkness from 7am to 9am, the cercarial emergence peak were delayed for the two isolates; whereas with an input of a 2 h darkness from 5pm to 7pm, neither effect on the cercarial emergence rhythm was observed. The total cercariae emerged for both parasite isolates varied with a different photoperiod. The results indicate that the change of photoperiod could affect the chronobiology of S japonicum cercarial emergence.

  20. Strong pituitary and hypothalamic responses to photoperiod but not to 6-methoxy-2-benzoxazolinone in female common voles (Microtus arvalis)

    NARCIS (Netherlands)

    Krol, Elzbieta; Douglas, Alex; Dardente, Hugues; Birnie, Mike J.; van der Vinne, Vincent; Eijer, Willem G.; Gerkema, Menno P.; Hazlerigg, David G.; Hut, Roelof A.; Król, Elżbieta

    2012-01-01

    The annual cycle of changing day length (photoperiod) is widely used by animals to synchronise their biology to environmental seasonality. In mammals, melatonin is the key hormonal relay for the photoperiodic message, governing thyroid-stimulating hormone (TSH) production in the pars tuberalis (PT)

  1. Strong pituitary and hypothalamic responses to photoperiod but not to 6-methoxy-2-benzoxazolinone in female common voles (Microtus arvalis)

    NARCIS (Netherlands)

    Krol, Elzbieta; Douglas, Alex; Dardente, Hugues; Birnie, Mike J.; van der Vinne, Vincent; Eijer, Willem G.; Gerkema, Menno P.; Hazlerigg, David G.; Hut, Roelof A.; Król, Elżbieta

    2012-01-01

    The annual cycle of changing day length (photoperiod) is widely used by animals to synchronise their biology to environmental seasonality. In mammals, melatonin is the key hormonal relay for the photoperiodic message, governing thyroid-stimulating hormone (TSH) production in the pars tuberalis (PT)

  2. Photoperiod Modulates Fast Delayed Rectifier Potassium Currents in the Mammalian Circadian Clock

    Directory of Open Access Journals (Sweden)

    Sahar Farajnia

    2016-09-01

    Full Text Available One feature of the mammalian circadian clock, situated in the suprachiasmatic nucleus (SCN, is its ability to measure day length and thereby contribute to the seasonal adaptation of physiology and behavior. The timing signal from the SCN, namely the 24 hr pattern of electrical activity, is adjusted according to the photoperiod being broader in long days and narrower in short days. Vasoactive intestinal peptide and gamma-aminobutyric acid play a crucial role in intercellular communication within the SCN and contribute to the seasonal changes in phase distribution. However, little is known about the underlying ionic mechanisms of synchronization. The present study was aimed to identify cellular mechanisms involved in seasonal encoding by the SCN. Mice were adapted to long-day (light–dark 16:8 and short-day (light–dark 8:16 photoperiods and membrane properties as well as K+ currents activity of SCN neurons were measured using patch-clamp recordings in acute slices. Remarkably, we found evidence for a photoperiodic effect on the fast delayed rectifier K+ current, that is, the circadian modulation of this ion channel’s activation reversed in long days resulting in 50% higher peak values during the night compared with the unaltered day values. Consistent with fast delayed rectifier enhancement, duration of action potentials during the night was shortened and afterhyperpolarization potentials increased in amplitude and duration. The slow delayed rectifier, transient K+ currents, and membrane excitability were not affected by photoperiod. We conclude that photoperiod can change intrinsic ion channel properties of the SCN neurons, which may influence cellular communication and contribute to photoperiodic phase adjustment.

  3. Photoperiod extension enhances sexual megaspore formation and triggers metabolic reprogramming in facultative apomictic Ranunculus auricomus

    Directory of Open Access Journals (Sweden)

    Simone eKlatt

    2016-03-01

    Full Text Available Abstract••Meiosis, the key step of sexual reproduction, persists in facultative apomictic plants functional to some extent. However, it still remains unclear how and why proportions of reproductive pathways vary under different environmental stress conditions. We hypothesized that oxidative stress mediates alterations of developmental pathways. In apomictic plants we expected that megasporogenesis, the stage directly after meiosis, would be more affected than later stages of seed development.•To simulate moderate stress conditions we subjected clone-mates of facultative apomictic Ranunculus auricomus to 10 h photoperiods, reflecting natural conditions, and extended ones (16.5 h. Reproduction mode was screened directly after megasporogenesis (microscope and at seed stage (flow cytometric seed screening. Targeted metabolite profiles were performed with HPLC−DAD to explore if and which metabolic reprogramming was caused by the extended photoperiod.•Prolonged photoperiods resulted in increased frequencies of sexual vs. aposporous initials directly after meiosis, but did not affect frequencies of sexual vs. asexual seed formation. Changes in secondary metabolite profiles under extended photoperiods affected all classes of compounds, and c. 20% of these changes separated the two treatments. Unexpectedly, the renowned antioxidant phenylpropanoids and flavonoids added more to clone-mate variation than to treatment differentiation. Among others, chlorophyll degradation products, non-assigned phenolic compounds and more lipophilic metabolites also contributed to the dissimilarity of the metabolic profiles of plants that had been exposed to the two different photoperiods.•The hypothesis of moderate light stress effects was supported by increased proportions of sexual megaspore development at the expense of aposporous initial formation. The lack of effects at the seed stage confirms the basic assumption that only meiosis and sporogenesis would

  4. Photoperiodic effects on short-pulse 14C assimilation and overall carbon and nitrogen allocation patterns in contrasting quinoa cultivars

    DEFF Research Database (Denmark)

    Bendevis, Mira Arpe; Sun, Yujie; Rosenqvist, Eva

    2014-01-01

    Further understanding of the range of environmental influence on source-sink relationships in quinoa is important to streamlining future crop improvement and efforts concerning geographic expansion of cultivation areas. In the present study a photoperiod sensitive quinoa cv. 'Achachino......' and photoperiod neutral cv. 'Titicaca' were studied under short (10h) and long (17.5h) days, with respect to C and N distribution as well as partitioning of newly assimilated C to plant organs. An extended photoperiod resulted in 14C decreasingly being allocated to stem growth and lower leaves in 'Titicaca...... with an immediate increase in carbon allocation to upper leaves, and over time to the reproductive structures, resulting in a more than 50% increase in final yield. Collectively the results indicate that even though the photoperiod sensitive cultivar flowered under long photoperiod it did not develop seeds, whereas...

  5. Temporal scale of the action of temperature and photoperiod on the xylogenesis at the treeline

    Directory of Open Access Journals (Sweden)

    Rossi S

    2007-01-01

    Full Text Available The possible role and interaction of two ecological factors, photoperiod and temperature, on xylogenesis of conifers growing at treeline are review. In cold climates, temperature is one of the major factors regulating metabolic activities of plants and influencing onset and rate of cell production during the growing period. However, photoperiod was found to act as a signal regulating the timing of maximum growth rate and synchronizing radial growth at annual level. During tree-ring formation, both factors are crucial but with different levels of interaction. Some recent findings about xylogenesis in cold environments are described and discussed

  6. Photoperiod regulates lean mass accretion, but not adiposity, in growing F344 rats fed a high fat diet.

    Directory of Open Access Journals (Sweden)

    Alexander W Ross

    Full Text Available In this study the effects of photoperiod and diet, and their interaction, were examined for their effects on growth and body composition in juvenile F344 rats over a 4-week period. On long (16L:8D, relative to short (8L:16D, photoperiod food intake and growth rate were increased, but percentage adiposity remained constant (ca 3-4%. On a high fat diet (HFD, containing 22.8% fat (45% energy as fat, food intake was reduced, but energy intake increased on both photoperiods. This led to a small increase in adiposity (up to 10% without overt change in body weight. These changes were also reflected in plasma leptin and lipid levels. Importantly while both lean and adipose tissue were strongly regulated by photoperiod on a chow diet, this regulation was lost for adipose, but not lean tissue, on HFD. This implies that a primary effect of photoperiod is the regulation of growth and lean mass accretion. Consistent with this both hypothalamic GHRH gene expression and serum IGF-1 levels were photoperiod dependent. As for other animals and humans, there was evidence of central hyposomatotropism in response to obesity, as GHRH gene expression was suppressed by the HFD. Gene expression of hypothalamic AgRP and CRH, but not NPY nor POMC, accorded with the energy balance status on long and short photoperiod. However, there was a general dissociation between plasma leptin levels and expression of these hypothalamic energy balance genes. Similarly there was no interaction between the HFD and photoperiod at the level of the genes involved in thyroid hormone metabolism (Dio2, Dio3, TSHβ or NMU, which are important mediators of the photoperiodic response. These data suggest that photoperiod and HFD influence body weight and body composition through independent mechanisms but in each case the role of the hypothalamic energy balance genes is not predictable based on their known function.

  7. World Nonproliferation Regime

    Institute of Scientific and Technical Information of China (English)

    Ouyang Liping; Wu Xingzuo

    2007-01-01

    2006 witnessed an intense struggle between nuclear proliferation and nonproliferation. Iran's nuclear issue and North Korea's nuclear test have cast a deep shadow over the current international nonproliferation regime. The international contest for civil nuclear development became especially fierce as global energy prices went up. Such a situation , to some extent, accelerated the pace of nuclear proliferation. Furthermore, the existing international nonproliferation regime, based upon the Nuclear Nonproliferation Treaty (NPT), was affected by loopholes, and the U.S. failed in its ambition to unite other forces to mend fences. The international community needs to come up with a comprehensive and long-term strategy to meet the demand for an effective future nonproliferation regime in a healthy nuclear order.

  8. The Pea Photoperiod Response Gene STERILE NODES Is an Ortholog of LUX ARRHYTHMO.

    Science.gov (United States)

    Liew, Lim Chee; Hecht, Valérie; Sussmilch, Frances C; Weller, James L

    2014-06-01

    The STERILE NODES (SN) locus in pea (Pisum sativum) was one of the first photoperiod response genes to be described and provided early evidence for the genetic control of long-distance signaling in flowering-time regulation. Lines homozygous for recessive sn mutations are early flowering and photoperiod insensitive, with an increased ability to promote flowering across a graft union in short-day conditions. Here, we show that SN controls developmental regulation of genes in the FT family and rhythmic regulation of genes related to circadian clock function. Using a positional and functional candidate approach, we identify SN as the pea ortholog of LUX ARRHYTHMO, a GARP transcription factor from Arabidopsis (Arabidopsis thaliana) with an important role in circadian clock function. In addition to induced mutants, sequence analysis demonstrates the presence of at least three other independent, naturally occurring loss-of-function mutations among known sn cultivars. Examination of genetic and regulatory interactions between SN and two other circadian clock genes, HIGH RESPONSE TO PHOTOPERIOD (HR) and DIE NEUTRALIS (DNE), suggests a complex relationship in which HR regulates expression of SN and the role of DNE and HR in control of flowering is dependent on SN. These results extend previous work to show that pea orthologs of all three Arabidopsis evening complex genes regulate clock function and photoperiod-responsive flowering and suggest that the function of these genes may be widely conserved.

  9. Photoperiodism of Male Offspring Production in the Water Flea Daphnia pulex.

    Science.gov (United States)

    Toyota, Kenji; Sato, Tomomi; Tatarazako, Norihisa; Iguchi, Taisen

    2017-08-01

    Photoperiodism is a biological seasonal timing system utilized to regulate development and reproduction in organisms. The freshwater micro-crustacean Daphnia pulex displays environmental sex determination, the precise physiological mechanisms of which are largely unknown due to the lack of an experimental system to induce female or male offspring production by alterations of the rearing environment. We recently found that D. pulex, WTN6 strain, produces female or male offspring in response to long-day or short-day conditions, respectively. Taking advantage of this system, here we report the photoperiodic response curve for male offspring production, showing 12 hours as natural critical daylength (50% incidence of male-producing mothers), and that male offspring inducibility is highly sensitive to photoperiodic alterations. By using monochromatic light emitting diode (LED) devices, we found that the effective wavelength is red-light (627 nm), which stably induces male offspring production. This suggests that the red-light photoreceptor may be decisive in the primary step of sex determination process in this strain. Our findings provide the first insights into photoperiodism and red-light as key factors in triggering male offspring production in daphnids.

  10. Linked circadian outputs control elongation growth and flowering in response to photoperiod and temperature

    NARCIS (Netherlands)

    Seaton, D.D.; Smith, R.W.; Young Hun Song,; MacGregor, D.R.; Stewart, K.; Steel, G.; Foreman, J.; Penfield, S.; Imaizumi, T.; Miller, A.J.; Halliday, K.J.

    2015-01-01

    Clock-regulated pathways coordinate the response of many developmental processes to changes in photoperiod and temperature. We model two of the best-understood clock output pathways in Arabidopsis, which control key regulators of flowering and elongation growth. In flowering, the model predicted reg

  11. Effects of photoperiod and hypothalamic knife cuts on the timing of FSH surges in hamsters.

    Science.gov (United States)

    Badura, L L; Sisk, C L; Nunez, A A

    1991-02-01

    The timing of the proestrous surge of follicle-stimulating hormone (FSH) was examined in female hamsters with hypothalamic knife cuts that prevented reproductive responses to photoperiod. All animals received either a horizontal knife cut aimed between the suprachiasmatic nuclei (SCN) and the paraventricular nuclei (PVN), or sham surgery, and were housed in long (16 h of light/24 h) or short (6 h of light/24 h) photoperiods. Following exposure to either photo-period for 11-12 weeks, a subset of the animals was fitted with an indwelling jugular cannula. Blood samples were taken hourly over a 24-h period and plasma levels of FSH were determined by RIA. Knife cuts placed ventral to or through the ventral portions of the PVN prevented short day-induced anestrus. On the day of proestrus, peak elevations of FSH in cycling animals with knife cuts in both photoperiods, as well as in sham-operated females in long days, occurred 4-5 h before lights out. In contrast, sham-operated anestrous females in short days showed peak elevations of FSH approximately 3-4 h after lights out. The present results support the view that neural connections between the SCN and the PVN mediate the effects of short days on reproductive physiology, including changes in the timing of the FSH surge.

  12. Yield and nutritive value of photoperiod-sensitive sorghum and sorghum-sudangrass in central Wisconsin

    Science.gov (United States)

    A study was conducted to evaluate the yield and nutrient composition of photoperiod sensitive (PS) and non-PS forage sorghum, sorghum-sudangrass, and sudangrass compared to corn planted on 2 dates and harvested using single or multiple-cut harvest strategies at 2 research stations (Marshfield and Ha...

  13. Photoperiod and growing degree days effect on dry matter partitioning in Jerusalem artichoke

    Science.gov (United States)

    The effect of photoperiod and growing degree days (GDD) on dry matter and dry partitioning in Jerusalem artichoke was investigated during 2008-09 and 2009-10. Three Jerusalem artichoke genotypes (CN-52867, JA-89 and HEL-65) were planted in 15 day-intervals between with thirteen different dates (Sep...

  14. Geographic variation in photoperiodic diapause induction and diapause intensity in Sericinus montelus (Lepidoptera: Papilionidae)

    Institute of Scientific and Technical Information of China (English)

    Xiao-Ping Wang; Qiu-Sheng Yang; Peter Dalin; Xing-Miao Zhou; Zhi-Wen Luo; Chao-Liang Lei

    2012-01-01

    Due to the risk of extinction and ornamental value of the swallowtail butterfly,Sericinus montelus Gray (Lepidoptera:Papilionidae) in China,knowledge about local adaptations is important for the conservation and economical utilization of the species.In the present study,photoperiodic diapause induction and diapause intensity of S.montelus populations from Jiamusi (46°37′N),Beijing (40°15′N),Zibo (36°48′N),Fangxian (32°36′N),Wuhan (30°33′N) and Huaihua (27°33′N) were characterized at 25℃.Logistic regression analysis revealed a significant population × hours of light interaction,confirming that photoperiodic responses varied among populations.The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude.Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25℃ and 16:8L:D h.The mean duration of pupal diapause was also positively correlated with latitude.Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S.montelus.These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.

  15. Effect of photoperiod on body mass, and daily energy intake and energy expenditure in young rats

    NARCIS (Netherlands)

    Boon, P; Visser, H; Daan, S

    1997-01-01

    In this experiment we investigate the effect of photoperiod on locomotor activity, body mass, food intake, growth efficiency (relationship between body mass change and food intake), energy expenditure, and body composition in growing Wistar rats. Two groups of animals were subjected to either a

  16. Evaluation of yield and quality of photoperiod sensitive sorghum and sorghum sudangrass

    Science.gov (United States)

    A 2-year study was conducted at 2 sites (Hancock, Marshfield) in central Wisconsin to assess yield and quality of photoperiod sensitive (PS) and non-PS sorghums in relation to corn planted on 2 dates and harvested once or twice. At each site, treatments were arranged as a split-split plot in a rando...

  17. Twilight and Photoperiod Affect Behavioral Entrainment in the House Mouse (Mus musculus)

    NARCIS (Netherlands)

    Comas, M.; Hut, R. A.

    2009-01-01

    The effect of twilight transitions on entrainment of C57BL/6JOlaHsd mice (Mus musculus) was studied using light-dark cycles of different photoperiods (6, 12, and 18 h) and twilight transitions of different durations (0, 1, and 2 h). Phase angle differences of the onset, center of gravity, and offset

  18. Mechanism of Sterility and Breeding Strategies for Photoperiod/Thermo- Sensitive Genic Male Sterile Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-yun; XIAO Ying-hui; LEI Dong-yang

    2010-01-01

    To understand the male sterility mechanism of photoperiod/thermo-sensitive genic male sterile [P(T)GMS] lines in rice, the research progress on genetics of photoperiod and/or temperature sensitive genic male sterility in rice was reviewed. A new idea was proposed to explain the sterility mechanism of P(T)GMS rice. The fertility transition from sterile to fertile is the result of cooperative regulation of major-effect sterile genes with photoperiod and/or temperature sensitive genes, but not the so-called pgms gene in P(T)GMS rice. The minor-effect genes, which exhibit accumulative effect on sterility, are the important factors for the critical temperature of sterility transition. The more minor-effect genes the sterile line holds, the lower the critical temperature of sterility transition is. The critical temperature of sterility transition will be invariable if all the minor-effect genes are homozygous. The strategies for breeding P(T)GMS rice were also proposed. The selective indices of critical photoperiod and temperature for sterility transition should be set according to varietal type and ecological region. Imposing selection pressure is a key technology for breeding P(T)GMS rice with lower critical temperature for sterility, and improving the comprehensive performance of the whole traits and combining ability is vital for breeding P(T)GMS rice lines.

  19. Photoperiodic control of the floral transition through a distinct polycomb repressive complex.

    Science.gov (United States)

    Wang, Yizhong; Gu, Xiaofeng; Yuan, Wenya; Schmitz, Robert J; He, Yuehui

    2014-03-31

    Polycomb group (PcG) complexes such as PRC1 mediate transcriptional repression. Here, we show that the plant-specific EMBRYONIC FLOWER1 (EMF1), LIKE HETEROCHROMATIN PROTEIN1, and a histone H3 lysine-4 demethylase form a distinct PcG complex, termed EMF1c, that plays PRC1-like roles and is crucial for regulation of the florigen gene FLOWERING LOCUS T (FT) in Arabidopsis. Long-day photoperiods promote FT expression activation in leaf veins specifically at dusk through the photoperiod pathway to induce Arabidopsis flowering. We found that before dusk and at night, a vascular EMF1c directly represses FT expression to prevent photoperiod-independent flowering, whereas at dusk EMF1 binding to FT chromatin is disrupted by the photoperiod pathway, leading to proper FT activation. Furthermore, a MADS-domain transcription factor and potent floral repressor binds EMF1 to repress FT expression. Our study reveals that the vascular EMF1c integrates inputs from several flowering-regulatory pathways to synchronize flowering time to environmental cues.

  20. Transcriptomic and proteomic analyses of seasonal photoperiodism in the pea aphid

    Directory of Open Access Journals (Sweden)

    Gauthier J-P

    2009-09-01

    Full Text Available Abstract Background Aphid adaptation to harsh winter conditions is illustrated by an alternation of their reproductive mode. Aphids detect photoperiod shortening by sensing the length of the night and switch from viviparous parthenogenesis in spring and summer, to oviparous sexual reproduction in autumn. The photoperiodic signal is transduced from the head to the reproductive tract to change the fate of the future oocytes from mitotic diploid embryogenesis to haploid formation of gametes. This process takes place in three consecutive generations due to viviparous parthenogenesis. To understand the molecular basis of the switch in the reproductive mode, transcriptomic and proteomic approaches were used to detect significantly regulated transcripts and polypeptides in the heads of the pea aphid Acyrthosiphon pisum. Results The transcriptomic profiles of the heads of the first generation were slightly affected by photoperiod shortening. This suggests that trans-generation signalling between the grand-mothers and the viviparous embryos they contain is not essential. By analogy, many of the genes and some of the proteins regulated in the heads of the second generation are implicated in visual functions, photoreception and cuticle structure. The modification of the cuticle could be accompanied by a down-regulation of the N-β-alanyldopamine pathway and desclerotization. In Drosophila, modification of the insulin pathway could cause a decrease of juvenile hormones in short-day reared aphids. Conclusion This work led to the construction of hypotheses for photoperiodic regulation of the switch of the reproductive mode in aphids.

  1. Regimes of justification

    NARCIS (Netherlands)

    Arts, Irma; Buijs, A.E.; Verschoor, G.M.

    2017-01-01

    Legitimacy of environmental management and policies is an important topic in environmental research. Based on the notion of ‘regimes of justification’, we aim to analyse the dynamics in argumentations used to legitimize and de-legitimize Dutch nature conservation practices. Contrary to prior

  2. Photoperiod affects the diurnal rhythm of hippocampal neuronal morphology of Siberian hamsters.

    Science.gov (United States)

    Ikeno, Tomoko; Weil, Zachary M; Nelson, Randy J

    2013-11-01

    Individuals of many species can regulate their physiology, morphology, and behavior in response to annual changes of day length (photoperiod). In mammals, the photoperiodic signal is mediated by a change in the duration of melatonin, leading to alterations in gene expressions, neuronal circuits, and hormonal secretion. The hippocampus is one of the most plastic structures in the adult brain and hippocampal neuronal morphology displays photoperiod-induced differences. Because the hippocampus is important for emotional and cognitive behaviors, photoperiod-driven remodeling of hippocampal neurons is implicated in seasonal differences of affect, including seasonal affective disorder (SAD) in humans. Because neuronal architecture is also affected by the day-night cycle in several brain areas, we hypothesized that hippocampal neuronal morphology would display a diurnal rhythm and that day length would influence that rhythm. In the present study, we examined diurnal and seasonal differences in hippocampal neuronal morphology, as well as mRNA expression of the neurotrophic factors (i.e., brain-derived neurotrophic factor [Bdnf], tropomyosin receptor kinase B [trkB; a receptor for BDNF], and vascular endothelial growth factor [Vegf]) and a circadian clock gene, Bmal1, in the hippocampus of Siberian hamsters. Diurnal rhythms in total length of dendrites, the number of primary dendrites, dendritic complexity, and distance of the furthest intersection from the cell body were observed only in long-day animals; however, diurnal rhythms in the number of branch points and mean length of segments were observed only in short-day animals. Spine density of dendrites displayed diurnal rhythmicity with different peak times between the CA1 and DG subregions and between long and short days. These results indicate that photoperiod affects daily morphological changes of hippocampal neurons and the daily rhythm of spine density, suggesting the possibility that photoperiod-induced adjustments

  3. Influence of photoperiod on growth for three desert CAM species. [Agave deserti, Ferocactus acanthodes, Opuntia ficus-indica

    Energy Technology Data Exchange (ETDEWEB)

    Nobel, P.S. (Univ. of California, Los Angeles (USA))

    1989-03-01

    Agave deserti, Ferocactus acanthodes, and Opuntia ficus-indica were maintained in environmental growth chambers under a constant total daily photosynthetically active radiation (PAR) for 1 yr to investigate the effects of photoperiod on growth of these Crassulacean acid metabolism (CAM) species. As the photoperiod was increased from 6 h to 18 h, growth increased 33% for A. deserti, 81% for F. acanthodes, and 50% for O. ficus-indica. Such increases were explained based on PAR saturation of the C{sub 3} photosynthetic carbon reduction cycle utilized by CAM plants during the daytime. In particular, the highest instantaneous PAR occurred for the shortest photoperiod and led to less growth for the same total daily PAR. Also, the total daily net CO{sub 2} uptake which occurred primarily at night, increased 53% as the photoperiod was increased from 6 to 18 h for O. ficus-indica, even though the accompanying night length decreased. The only other observed morphological effect was the sevenfold increase in the number of new cladodes initiated as the photoperiod was increased from 6 h to 18 h for O. ficus-indica. The influence of photoperiod on the daily pattern of net CO{sub 2} uptake and lack of effect of drought on plant survival under long photoperiods for O. ficus-indica differ from previous reports on this and other CAM species.

  4. Photoperiod regulates multiple gene expression in the suprachiasmatic nuclei and pars tuberalis of the Siberian hamster (Phodopus sungorus).

    Science.gov (United States)

    Johnston, Jonathan D; Ebling, Francis J P; Hazlerigg, David G

    2005-06-01

    Photoperiod regulates the seasonal physiology of many mammals living in temperate latitudes. Photoperiodic information is decoded by the master circadian clock in the suprachiasmatic nuclei (SCN) of the hypothalamus and then transduced via pineal melatonin secretion. This neurochemical signal is interpreted by tissues expressing melatonin receptors (e.g. the pituitary pars tuberalis, PT) to drive physiological changes. In this study we analysed the photoperiodic regulation of the circadian clockwork in the SCN and PT of the Siberian hamster. Female hamsters were exposed to either long or short photoperiod for 8 weeks and sampled at 2-h intervals across the 24-h cycle. In the SCN, rhythmic expression of the clock genes Per1, Per2, Cry1, Rev-erbalpha, and the clock-controlled genes arginine vasopressin (AVP) and d-element binding protein (DBP) was modulated by photoperiod. All of these E-box-containing genes tracked dawn, with earlier peak mRNA expression in long, compared to short, photoperiod. This response occurred irrespective of the presence of additional regulatory cis-elements, suggesting photoperiodic regulation of SCN gene expression through a common E-box-related mechanism. In long photoperiod, expression of Cry1 and Per1 in the PT tracked the onset and offset of melatonin secretion, respectively. However, whereas Cry1 tracked melatonin onset in short period, Per1 expression was not detectably rhythmic. We therefore propose that, in the SCN, photoperiodic regulation of clock gene expression primarily occurs via E-boxes, whereas melatonin-driven signal transduction drives the phasing of a subset of clock genes in the PT, independently of the E-box.

  5. Mapping QTL associated with photoperiod sensitivity and assessing the importance of QTL×environment interaction for flowering time in maize.

    Directory of Open Access Journals (Sweden)

    Cuiling Wang

    Full Text Available BACKGROUND: An understanding of the genetic determinism of photoperiod response of flowering is a prerequisite for the successful exchange of germplasm across different latitudes. In order to contribute to resolve the genetic basis of photoperiod sensitivity in maize, a set of 201 recombinant inbred lines (RIL, derived from a temperate and tropical inbred line cross were evaluated in 5 field trials spread in short- and long-day environments. METHODOLOGY/PRINCIPAL FINDINGS: Firstly, QTL analyses for flowering time and photoperiod sensitivity in maize were conducted in individual photoperiod environments separately, and then, the total genetic effect was partitioned into additive effect (A and additive-by-environment interaction effect (AE by using a mixed-model-based composite interval mapping (MCIM method. CONCLUSIONS/SIGNIFICANCE: Seven putative QTL were found associated with DPS thermal time based on the data estimated in individual environments. Nine putative QTL were found associated with DPS thermal time across environments and six of them showed significant QTL×enviroment (QE interactions. Three QTL for photoperiod sensitivity were identified on chromosome 4, 9 and 10, which had the similar position to QTL for DPS thermal time in the two long-day environment. The major photoperiod sensitive loci qDPS10 responded to both short and long-day photoperiod environments and had opposite effects in different photoperiod environment. The QTL qDPS3, which had the greatest additive effect exclusively in the short-day environment, were photoperiod independent and should be classified in autonomous promotion pathway.

  6. Effect of photoperiod stress assessment and locomotor activity of female lambari (Astyanax bimaculatu

    Directory of Open Access Journals (Sweden)

    Fernanda Keley Silva Pereira Navarro

    2014-04-01

    Full Text Available Some studies and scientific investments have been done in aquaculture aiming to minimize the stress of the fish due to different factors, as management, nutritional status, water quality, temperature, photoperiod, and salinity. This study aimed to verify the effect of photoperiod on locomotor activity and plasma levels of cortisol and glucose in female Lambari. One hundred and twenty female Lambari adult were maintained in aquaria of 20 liters each in a completely randomized design with three treatments (T1 = 0Light: 24Dark, T2 = 12L: 12D, T3 = 24L: 0D and four replications. The daily locomotor activity was registered during 15 days using an infrared photocell. After 40 days of experiment and previous fasting for 24 hours, fish were euthanized by a lethal dose of benzocaine. Female Lambari featured a diurnal rhythm of locomotor activity. Lambari subjected to 12:12 and LD photoperiod presented higher cortisol (12L:12E: 190.00 ± 37.73 ng/mL e 24L:0E: 148.850 ± 32.77 ng/mL and locomotor activity levels and also lower survival rates (30.0 ± 7.07% when compared to the LD photoperiod (cortisol: 85.570 ± 7.99 ng/mL, survival rates: 72.5 ± 4.330%. The glucose concentration (32.167 ± 22.73 mg/dL and the growth (7.050 ±0.59cm of fish subjected to LD photoperiod was significantly lower than in the other treatments. We conclude that light plays an important role in the growth, behavior and welfare of female Lambari. Besides, our data highlighted that fish submitted to a long light period present a more stressed and more aggressive status when compared to fish submitted to a continuous darkness.

  7. Footprints of natural and artificial selection for photoperiod pathway genes in Oryza.

    Science.gov (United States)

    Huang, Chao-Li; Hung, Cheng-Yu; Chiang, Yu-Chung; Hwang, Chi-Chuan; Hsu, Tsai-Wen; Huang, Chi-Chun; Hung, Kuo-Hsiang; Tsai, Kun-Chan; Wang, Kuo-Hsiung; Osada, Naoki; Schaal, Barbara Anna; Chiang, Tzen-Yuh

    2012-06-01

    Asian rice, Oryza sativa, consists of two major subspecies, indica and japonica, which are physiologically differentiated and adapted to different latitudes. Genes for photoperiod sensitivity are likely targets of selection along latitude. We examined the footprints of natural and artificial selections for four major genes of the photoperiod pathway, namely PHYTOCHROME B (PhyB), HEADING DATE 1 (Hd1), HEADING DATE 3a (Hd3a), and EARLY HEADING DATE 1 (Ehd1), by investigation of the patterns of nucleotide polymorphisms in cultivated and wild rice. Geographical subdivision between tropical and subtropical O. rufipogon was found for all of the photoperiod genes in plants divided by the Tropic of Cancer (TOC). All of these genes, except for PhyB, were characterized by the existence of clades that split a long time ago and that corresponded to latitudinal subdivisions, and revealed a likely diversifying selection. Ssp. indica showed close affinity to tropical O. rufipogon for all genes, while ssp. japonica, which has a much wider range of distribution, displayed complex patterns of differentiation from O. rufipogon, which reflected various agricultural needs in relation to crop yield. In japonica, all genes, except Hd3a, were genetically differentiated at the TOC, while geographical subdivision occurred at 31°N in Hd3a, probably the result of varying photoperiods. Many other features of the photoperiod genes revealed domestication signatures, which included high linkage disequilibrium (LD) within genes, the occurrence of frequent and recurrent non-functional Hd1 mutants in cultivated rice, crossovers between subtropical and tropical alleles of Hd1, and significant LD between Hd1 and Hd3a in japonica and indica.

  8. Evidence for Weakened Intercellular Coupling in the Mammalian Circadian Clock under Long Photoperiod

    Science.gov (United States)

    Buijink, M. Renate; Almog, Assaf; Wit, Charlotte B.; Roethler, Ori; Olde Engberink, Anneke H. O.; Meijer, Johanna H.; Garlaschelli, Diego; Rohling, Jos H. T.; Michel, Stephan

    2016-01-01

    For animals living in temperate latitudes, seasonal changes in day length are an important cue for adaptations of their physiology and behavior to the altered environmental conditions. The suprachiasmatic nucleus (SCN) is known as the central circadian clock in mammals, but may also play an important role in adaptations to different photoperiods. The SCN receives direct light input from the retina and is able to encode day-length by approximating the waveform of the electrical activity rhythm to the duration of daylight. Changing the overall waveform requires a reorganization of the neuronal network within the SCN with a change in the degree of synchrony between the neurons; however, the underlying mechanisms are yet unknown. In the present study we used PER2::LUC bioluminescence imaging in cultured SCN slices to characterize network dynamics on the single-cell level and we aimed to provide evidence for a role of modulations in coupling strength in the photoperiodic-induced phase dispersal. Exposure to long photoperiod (LP) induced a larger distribution of peak times of the single-cell PER2::LUC rhythms in the anterior SCN, compared to short photoperiod. Interestingly, the cycle-to-cycle variability in single-cell period of PER2::LUC rhythms is also higher in the anterior SCN in LP, and is positively correlated with peak time dispersal. Applying a new, impartial community detection method on the time series data of the PER2::LUC rhythm revealed two clusters of cells with a specific spatial distribution, which we define as dorsolateral and ventromedial SCN. Post hoc analysis of rhythm characteristics of these clusters showed larger cycle-to-cycle single-cell period variability in the dorsolateral compared to the ventromedial cluster in the anterior SCN. We conclude that a change in coupling strength within the SCN network is a plausible explanation to the observed changes in single-cell period variability, which can contribute to the photoperiod-induced phase

  9. RFRP neurons are critical gatekeepers for the photoperiodic control of reproduction

    Directory of Open Access Journals (Sweden)

    Valerie eSimonneaux

    2012-12-01

    Full Text Available Seasonally-breeding mammals rely on the photoperiodic signal to restrict their fertility to a certain time of the year. The photoperiodic information is translated in the brain via the pineal hormone melatonin, and it is now well established that it is the variation in the duration of the nocturnal peak of melatonin which synchronises reproduction with the seasons. The Syrian hamster is a long day breeder, and sexual activity is therefore promoted by exposure to a long day photoperiod and inhibited by exposure to a short day photoperiod. Interestingly, in this species electrolytic lesion of the mediobasal hypothalamus abolishes the short day-induced gonadal regression. We have shown that the expression of a recently discovered neuronal population, namely RFamide-related peptide (rfrp neurons, present in the mediobasal hypothalamus, is strongly down-regulated by melatonin in short day conditions, but not altered by circulating levels of sex steroids. The role of rfrp and its product RFRP-3 in the regulation of reproductive activity has been extensively studied in mammals, and our recent findings indicate that this peptide is a potent stimulator of the reproductive axis in the Syrian hamster. It induces a marked increase in GnRH neuron activity and gonadotrophin secretion, and it is able to rescue reproductive activity in short day sexually inactive hamsters. Little is known about the localisation of the RFRP-3 receptor, GPR147, in the rodent brain. Accumulating evidence suggests that RFRP-3 could be acting via two intermediates, the GnRH neurons in the preoptic area and the Kiss1 neurons in the arcuate nucleus, but future studies should aim at describing the localisation of Gpr147 in the Syrian hamster brain. Altogether our data indicate that the rfrp neuronal population within the mediobasal hypothalamus might be a serious candidate in mediating the photoperiodic effects of melatonin on the regulation of the reproductive axis.

  10. Assessment of anoxia tolerance and photoperiod dependence of GABAergic polarity in the pond snail Lymnaea stagnalis.

    Science.gov (United States)

    Buck, Leslie T; Bond, Hilary C; Malik, Aqsa

    2017-01-01

    The pond snail Lymnaea stagnalis is reported to be anoxia-tolerant and if the tolerance mechanism is similar to that of the anoxia-tolerant painted turtle, GABA should play an important role. A potentially confounding factor investigating the role of GABA in anoxia tolerance are reports that GABA has both inhibitory and excitatory effects within L. stagnalis central ganglion. We therefore set out to determine if seasonality or photoperiod has an impact on: 1) the anoxia-tolerance of the intact pond snail, and 2) the response of isolated neuroganglia cluster F neurons to exogenous GABA application. L. stagnalis maintained on a natural summer light cycle were unable to survive any period of anoxic exposure, while those maintained on a natural winter light cycle survived a maximum of 4h. Using intracellular sharp electrode recordings from pedal ganglia cluster F neurons we show that there is a photoperiod dependent shift in the response to GABA. Snails exposed to a 16h:8h light:dark cycle in an environmental chamber (induced summer phenotype) exhibited hyperpolarizing inhibitory responses and those exposed to a 8h:16h light:dark cycle (induced winter phenotype) exhibited depolarizing excitatory responses to GABA application. Using gramicidin-perforated patch recordings we also found a photoperiod dependent shift in the reversal potential for GABA. We conclude that the opposing responses of L. stagnalis central neurons to GABA results from a shift in intracellular chloride concentration that is photoperiod dependent and is likely mediated through the relative efficacy of cation chloride co-transporters. Although the physiological ramifications of the photoperiod dependent shift are unknown this work potentially has important implications for the impact of artificial light pollution on animal health. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Influence of photoperiod on Orius thyestes Herring (Hemiptera: Anthocoridae) reproduction and longevity.

    Science.gov (United States)

    Carvalho, Alessandra R; Bueno, Vanda H P; Pedroso, Elizabeth C; Kon, Leonardo I; Diniz, Alexandre J F; Silva, Robson J

    2006-01-01

    Several species of Orius Wolff are used in biological control of thrips in protected cultivations in temperate regions, but some of them show reproductive diapause, compromising the efficiency of these agents of biological control. There are no reports on the biology of the neotropical species Orius thyestes Herring under different environmental conditions. The purpose of this work was to investigate the influence of photoperiod on reproduction and longevity of this predator. Nymphs were kept in petri dishes in climatic chambers at 28+/-1 degree C, 70+/-10% RH and under the photoperiods of 12L:12D, 11L:13D, 10 L:14D e 09L:15D. The mating adults were kept in petri dishes with Bidens pilosa L. Asteraceae inflorescences as oviposition substracts and eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) as food. The pre-oviposition and oviposition periods, fecundity and longevity were evaluated and O. thyestes did not show reprodutive diapause in all photoperiod conditions established. The mean number of eggs obtained per female decreased with the reduction of the photophase, with a difference (P < 0.05) between the values obtained in 12h and 9h of photophase. Longevity of females and males under 9h photophase was shorter (P < 0.05) than in all other photoperiods tested. The knowledge of the biology of the natural enemy under different conditions allows to optimise the mass rearing and to predict the performance of the predator in different photoperiods which may occur along the year and in greenhouses.

  12. Long photoperiods sustain high pH in Arctic kelp forests.

    Science.gov (United States)

    Krause-Jensen, Dorte; Marbà, Núria; Sanz-Martin, Marina; Hendriks, Iris E; Thyrring, Jakob; Carstensen, Jacob; Sejr, Mikael Kristian; Duarte, Carlos M

    2016-12-01

    Concern on the impacts of ocean acidification on calcifiers, such as bivalves, sea urchins, and foraminifers, has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows. The metabolism of these habitats can lead to diel fluctuation in pH with increases during the day and declines at night, suggesting no net effect on pH at time scales longer than daily. We examined the capacity of subarctic and Arctic kelps to up-regulate pH in situ and experimentally tested the role of photoperiod in determining the capacity of Arctic macrophytes to up-regulate pH. Field observations at photoperiods of 15 and 24 hours in Greenland combined with experimental manipulations of photoperiod show that photoperiods longer than 21 hours, characteristic of Arctic summers, are conducive to sustained up-regulation of pH by kelp photosynthesis. We report a gradual increase in pH of 0.15 units and a parallel decline in pCO2 of 100 parts per million over a 10-day period in an Arctic kelp forest over midsummer, with ample scope for continued pH increase during the months of continuous daylight. Experimental increase in CO2 concentration further stimulated the capacity of macrophytes to deplete CO2 and increase pH. We conclude that long photoperiods in Arctic summers support sustained up-regulation of pH in kelp forests, with potential benefits for calcifiers, and propose that this mechanism may increase with the projected expansion of Arctic vegetation in response to warming and loss of sea ice.

  13. Coast cross (Cynodon dactylon (L. pers. hay and pigeon pea (Cajanus cajan (L. millsp digestibility and nutrients average intake by sheep under two feeding systems/ Consumo médio e digestibilidade do feno de capim “Coast cross” (Cynodon dactylon (L. pers. e feijão guandu (Cajanus cajan (L. Millsp em carneiros submetidos a dois regimes alimentares

    Directory of Open Access Journals (Sweden)

    Luiz Waldemar de Oliveira Souza

    2007-08-01

    Full Text Available This experiment was carried out with the objectives of determining the daily average intake (DAI, apparent digestibility coefficient (ADC of coast cross hay and pigeon pea nutrients and to evaluate thenitrogen balance in sheep. Ten wethers with average weight of 27.50 kg, alloted to suitable cages, were used. A completely randomized design with two treatments (T1= 80% coast cross hay + 20% pigeon peaand T2= 60% coast cross hay + 40% pigeon pea and five replicates, was used. The treatments were evaluated under two feeding systems (voluntary and restrict. Animals receiving ration of T2 presentedhigher DAI (g/kg PV 0.75 (PO experimento foi realizado com os objetivos de determinar o consumo médio diário (CMD, o coeficiente de digestibilidade aparente (CDA dos nutrientes do feno de capim Coast cross e feijão guandu e avaliar o balanço de nitrogênio (BN em ovinos. Foram utilizados dez ovinos machos, castrados, com peso médio de 27,50 kg, alojados em gaiolas para metabolismo, em delineamento inteiramente casualizado com dois tratamentos (T1 = 80% de feno de Coast cross + 20% de guandu e T2 = 60% de feno de Coast cross + 40% de guandu e cinco repetições por tratamento. Os tratamentos foram avaliados sob dois regimes alimentares (consumo voluntário e restrito. Os animais recebendo ração do T2 apresentaram maior CMD (g/kg PV0,75 (p < 0,05 de matéria seca (MS, proteína bruta (PB, fibra bruta (FB, matéria orgânica (MO e extrato não nitrogenado (ENN, do que aqueles animais recebendo ração do T1. O CDA da FB da ração T2 foi maior (p < 0,05 do que o da ração T1. O BN dos animais que receberam 40% de guandu (13,15g N/ dia foi superior aos daqueles que receberam 20% desta leguminosa (10,29g N/dia. Conclui-se que o feijão guandu pode ser utilizado como fonte protéica na alimentação de ruminantes, possibilitando CDA da MS próximo de 52% para animais em regime de consumo voluntário, e 81% para animais em regime de consumo restrito. O

  14. Regimes Of Helium Burning

    CERN Document Server

    Timmes, F X

    2000-01-01

    The burning regimes encountered by laminar deflagrations and ZND detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts which start with a thermonuclear runaway on the surface of a neutron star, and the thin shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial directions encounter a transition from the distributed regime to the flamlet regime at a density of 10^8 g cm^{-3}. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than 10^6 g cm^{-3}. Self-sustained laminar deflagrations travelling in the radial direction cannot exist below this density. Similarily, the planar ZND detonation width becomes larger than the pressure scale height at 10^7 g cm^{-3}, suggesting that a steady-state, self-sustained detonations cannot come into exista...

  15. Optimizing the co-feeding strategy of Persian sturgeon (Acipenser persicus larvae using Artemia nauplii and formulated diet

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    Naser Agh

    2013-07-01

    Full Text Available High mortality and labor costs are associated with first-feeding sturgeon culture, particularly during the period of dietary transition from live to formulated feed. Therefore we investigated the effects of various feeding treatments on the survival and growth of the Persian sturgeon (Acipenser persicus larvae during a 20-day culture period. Three replicate groups (250 fish/replicate of first-feeding larvae were fed according to four main feeding regimes: (1 live food (live nauplii of brine shrimp Artemia urmiana; (2 indirect transition (5 days live food followed by gradual transition to formulated diet; (3 direct transition (using different combinations of live and formulated diet from the start feeding onwards; (4 formulated feed (FD from the start feeding. Results indicated that growth and survival were higher in the indirect transition feeding regime than in other regimes. Based on our study, co-feeding of A. persicus should start five days after prior feeding with live food.

  16. Altered electroencephalographic activity associated with changes in the sleep-wakefulness cycle of C57BL/6J mice in response to a photoperiod shortening

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    Stanislav Rozov

    2016-08-01

    Full Text Available AimUnder natural conditions diurnal rhythms of biological processes of the organism are synchronized with each other and to the environmental changes by means of the circadian system. Disturbances of the latter affect hormonal levels, sleep-wakefulness cycle and cognitive performance. To study mechanisms of such perturbations animal models subjected to artificial photoperiods are often used. The goal of current study was to understand the effects of circadian rhythm disruption, caused by a short light-dark cycle regime, on activity of the cerebral cortex in rodents.MethodsWe used electroencephalogram to assess the distribution of vigilance states, perform spectral analysis, and estimate the homeostatic sleep drive. In addition, we analyzed spontaneous locomotion of C57BL/6J mice under symmetric, 22-h-, 21-h-, and 20-h-long light–dark cycles using video recording and tracking methods.Results and ConclusionsWe found that shortening of photoperiod caused a significant increase of slow wave activity during non-rapid eye movement sleep suggesting an elevation of sleep pressure under such conditions. While the rhythm of spontaneous locomotion was completely entrained by all light–dark cycles tested, periodic changes in the power of the θ- and γ-frequency ranges during wakefulness gradually disappeared under 22-h- and 21-h-long light–dark cycles. This was associated with a significant increase in the θ–γ phase-amplitude during wakefulness. Our results thus provide deeper understanding of the mechanisms underlying the impairment of learning and memory retention, which is associated with disturbed circadian regulation.

  17. Altered Electroencephalographic Activity Associated with Changes in the Sleep-Wakefulness Cycle of C57BL/6J Mice in Response to a Photoperiod Shortening

    Science.gov (United States)

    Rozov, Stanislav V.; Zant, Janneke C.; Gurevicius, Kestutis; Porkka-Heiskanen, Tarja; Panula, Pertti

    2016-01-01

    Aim: Under natural conditions diurnal rhythms of biological processes of the organism are synchronized with each other and to the environmental changes by means of the circadian system. Disturbances of the latter affect hormonal levels, sleep-wakefulness cycle and cognitive performance. To study mechanisms of such perturbations animal models subjected to artificial photoperiods are often used. The goal of current study was to understand the effects of circadian rhythm disruption, caused by a short light-dark cycle regime, on activity of the cerebral cortex in rodents. Methods: We used electroencephalogram to assess the distribution of vigilance states, perform spectral analysis, and estimate the homeostatic sleep drive. In addition, we analyzed spontaneous locomotion of C57BL/6J mice under symmetric, 22-, 21-, and 20-h-long light–dark cycles using video recording and tracking methods. Results and Conclusions: We found that shortening of photoperiod caused a significant increase of slow wave activity during non-rapid eye movement sleep suggesting an elevation of sleep pressure under such conditions. While the rhythm of spontaneous locomotion was completely entrained by all light–dark cycles tested, periodic changes in the power of the θ- and γ-frequency ranges during wakefulness gradually disappeared under 22- and 21-h-long light–dark cycles. This was associated with a significant increase in the θ–γ phase-amplitude coupling during wakefulness. Our results thus provide deeper understanding of the mechanisms underlying the impairment of learning and memory retention, which is associated with disturbed circadian regulation. PMID:27630549

  18. Growth performance, feed digestibility, body composition, and feeding behavior of high- and low-residual feed intake fat-tailed lambs under moderate feed restriction.

    Science.gov (United States)

    Rajaei Sharifabadi, H; Naserian, A A; Valizadeh, R; Nassiry, M R; Bottje, W G; Redden, R R

    2016-08-01

    Two experiments were conducted to evaluate the effect of moderate feed restriction on productivity of lambs classified on the basis of phenotypic expression of residual feed intake (RFI). In Exp. 1, 58 fat-tailed Kurdi ram lambs (32.1 ± 4.2 kg BW) were individually fed, ad libitum, a pelleted diet (35% alfalfa hay and 65% concentrate). Feed intake and ADG were determined for a 6-wk period and 3 feed efficiency measures including RFI, G:F, and partial efficiency of maintenance (PEM) were calculated. The lambs were sorted based on RFI and the 16 highest RFI (RFI ≥ mean + 0.5 SD) and 16 lowest RFI (RFI ≤ mean - 0.5 SD) lambs were subjected to body composition (BC) and DM digestibility (DMD) analysis. Feeding behavior traits (FB) were also evaluated for 24 h using a regular 5-min interval observation method. The high- and low-RFI lambs (14 lambs/RFI group) so classified in Exp. 1 were used in Exp. 2. Half of the lambs in each RFI group were randomly selected to be fed ad libitum or 85% of ad libitum (restricted feeding), which resulted in 4 experimental groups: 1) ad libitum high-RFI, 2) feed restricted high-RFI, 3) ad libitum low-RFI, and 4) feed restricted low-RFI. The lambs were fed the same diet as Exp. 1, and growth efficiency during a 6-wk test period as well as BC, DMD, and FB were also determined in Exp. 2. In Exp. 1, the low-RFI lambs consumed 14% ( feed than high-RFI lambs. Differences were also observed between high- and low-RFI groups for G:F ( = 0.01), RFI ( 0.72), and FB ( > 0.24). In Exp.2, the restriction feeding regime negatively affected ADG ( feed restriction condition. No effects of feed restriction on DMD ( = 0.87) and BC ( > 0.05) were observed. The lambs fed at the restricted level of intake presented a greater time ( feeding events were decreased ( feed restriction, no interaction ( > 0.05) was detected between RFI phenotype and feeding regime for FB. In summary, feeding high-RFI lambs at 85% of ad libitum level improved G:F with no effect

  19. Proteomic analysis of shoot tissue during photoperiod induced growth cessation in V. riparia Michx. grapevines

    Directory of Open Access Journals (Sweden)

    Victor Kim J

    2010-08-01

    Full Text Available Abstract Background Growth cessation, cold acclimation and dormancy induction in grapevines and other woody perennial plants native to temperate continental climates is frequently triggered by short photoperiods. The early induction of these processes by photoperiod promotes winter survival of grapevines in cold temperate zones. Examining the molecular processes, in particular the proteomic changes in the shoot, will provide greater insight into the signaling cascade that initiates growth cessation and dormancy induction. To begin understanding transduction of the photoperiod signal, Vitis riparia Michx. grapevines that had grown for 35 days in long photoperiod (long day, LD, 15 h were subjected to either a continued LD or a short photoperiod (short day, SD, 13 h treatment. Shoot tips (4-node shoot terminals were collected from each treatment at 7 and 28 days of LD and SD for proteomic analysis via two-dimensional (2D gel electrophoresis. Results Protein profiles were characterized in V. riparia shoot tips during active growth or SD induced growth cessation to examine physiological alterations in response to differential photoperiod treatments. A total of 1054 protein spots were present on the 2D gels. Among the 1054 proteins, 216 showed differential abundance between LD and SD (≥ two-fold ratio, p-value ≤ 0.05. After 7 days, 39 protein spots were more abundant in LD and 30 were more abundant in SD. After 28 days, 93 protein spots were more abundant in LD and 54 were more abundant in SD. MS/MS spectrometry was performed to determine the functions of the differentially abundant proteins. Conclusions The proteomics analysis uncovered a portion of the signal transduction involved in V. riparia grapevine growth cessation and dormancy induction. Different enzymes of the Calvin-Benson cycle and glutamate synthetase isoforms were more abundant either in LD or SD treatments. In LD tissues the significantly differentially more abundant proteins

  20. Effect of photoperiod on some biological parameters of Clarias gariepinus juvenile

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    Solomon S. G.

    2012-11-01

    Full Text Available Photoperiod effect on Growth parameters and cannibalism of Clarias gariepinushave been well documented in resent past, but little is known about the response of other biological parameters such as, Condition factor, Shooters composition, Body colouration and Blood glucose of this important tropical fish species to different photoperiods, therefore the present study was designed to evaluate these responses of the African catfish to 24 hours of light (00D:24L, 24 hours of darkness (24D: 00L and 12 hour light / 12 hours darkness (12D: 12L. The six weeks experiment observed significant differences (P0.05 at the end of the experiment and were Significantly lower than value obtained at the start of the experiment, Shooters composition was highest in 00D:24L (41.5% i.e. 27 of 65 leading to high mortality (13.33% due to cannibalism compared to 12D: 12L (Shooters =15.27% i.e. 11 of 72, Mortality= 4% and 24D: 00L (Shooters=5.33% i.e. 4 of 75, Mortality= 0% photoperiod. More so, 93.33% (70 of 75 of fish in the dark phase (24D: 00Lexhibited Deep shiny black body colouration, while 6.67% (5 of 75 was observed of Normal fish colouration. However the fishes in the 00D: 24L photoperiod were observed to be predominantly Lighter skin colouration, (80% i.e. 52 of 65= lighter colouration, 18.46% i.e. 12 of 65= Normal skin coloration and 1.53 i.e. 1 of 65= Deep black body colouration while 12D: 12L were of Normal skin colouration (100% Normal skin colouration, also blood glucose was observed to increase as the light hours increased (P<0.05 with 24D: 00L photoperiod having the highest blood glucose level of 5.7+0.5, while those in 12D: 12L had 4.4+0.3 and 24D: 00L had the least value of 3.9+0.1. This study therefore establishes the fact that photoperiod may have no effect on the condition factor of African catfish, while higher shooters composition is highlighted as one of the causes of increased mortality and could be reduced to a large extent with reduced light

  1. Phytohormones level in the leaves of Hyoscyamus niger L. during variable photoperiods at the time of flower initiation and differentiation

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    Jan Kopcewicz

    2014-02-01

    Full Text Available The investigations concern changes in the content of endogenous phytohormones in the leaves of the long-day plant Hyoscyamus niger L. during variable photoperiods applied before and after flower initiation. The results show that alternation of inductive photoperiods with short days leads to quantitative changes in the content of phytohormones. The changeable photoperiod leads to a general decrease in the contents of gibberellins, cytokinins and auxins during the short noninductive days both before and after flower initiation. Alternation of the inductive photoperiod with short days does not influence the content of abscisic acid-like substances before flower initiation and causes an increase of the amount of inhibitors in the postinductive period. The content of hormonal substances is subjected to rhytmical changes related to the periods of light and darkness in the twenty-four hours' cycle.

  2. Melatonin and 6-methoxy-2-benzoxazolinone (6-MBOA) alter the response of the male Syrian hamster to natural photoperiod

    Science.gov (United States)

    Vaughan, M. K.; Little, J. C.; Powell, D. C.; Puig-Domingo, M.; Reiter, R. J.

    1988-06-01

    Adult male hamsters bearing either a blank beeswax, 6-methoxy-2-benzoxazolinone (6-MBOA), or melatonin pellet were exposed to 8 weeks (Oct. 6 Dec. 6) of natural autumn decreasing photoperiod (beeswax pellet. When one compares the various effects of 6-MBOA and melatonin (2 mg/month) on the reproductive system of the male hamster, 6-MBOA is not as effective as melatonin in altering reproductive responses to short photoperiod and cool temperatures at the dose administered.

  3. Residual feed intake in beef cattle

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    J P.F. Arthur

    2008-07-01

    Full Text Available Providing feed is a major input cost in beef production, hence improvements in the efficiency of feed utilisation will reduce the cost of production. Residual feed intake (RFI is a measure of feed efficiency, and is defined as the difference between an animal's actual feed intake and its expected feed intake based on its size and growth. It is independent of the level of production, and the lower the value the more efficient the animal is. This paper examines the current state of knowledge on RFI. Available information indicates that postweaning RFI is moderately heritable, and that selection for low RFI will result in progeny that consume less feed for the same level of production as progeny of high RFI cattle. Under ad libitum feeding, RFI is phenotypically independent of growth traits. There is a weak genetic relationship between RFI and fatness but additional studies are needed to assess the magnitude of this relationship in different breeds, sexes, ages and feeding regimes. Residual feed intake is believed to represent inherent variation in basic metabolic processes which determine efficiency. Economic analyses of genetic improvement schemes that incorporate testing of individuals for RFI have yielded substantial economic benefits over and above existing schemes that do not include RFI testing. Selection for low RFI has an additional benefit of reducing greenhouse gas emissions by cattle.

  4. East Asian welfare regime

    DEFF Research Database (Denmark)

    Abrahamson, Peter

    2017-01-01

    . Political science studies tend to conclude that the region has left the old legacies behind and are now welfare states comparable to European states including them either in the conservative type (e.g. Japan), the liberal type (e.g. Korea) or even as a tendency in the Nordic type (e.g. China), while studies......The paper asks if East Asian welfare regimes are still productivist and Confucian? And, have they developed public care policies? The literature is split on the first question but (mostly) confirmative on the second. Care has to a large, but insufficient extent, been rolled out in the region...

  5. Effects of Photoperiod Extension on Clock Gene and Neuropeptide RNA Expression in the SCN of the Soay Sheep.

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    Hugues Dardente

    Full Text Available In mammals, changing daylength (photoperiod is the main synchronizer of seasonal functions. The photoperiodic information is transmitted through the retino-hypothalamic tract to the suprachiasmatic nuclei (SCN, site of the master circadian clock. To investigate effects of day length change on the sheep SCN, we used in-situ hybridization to assess the daily temporal organization of expression of circadian clock genes (Per1, Per2, Bmal1 and Fbxl21 and neuropeptides (Vip, Grp and Avp in animals acclimated to a short photoperiod (SP; 8h of light and at 3 or 15 days following transfer to a long photoperiod (LP3, LP15, respectively; 16h of light, achieved by an acute 8-h delay of lights off. We found that waveforms of SCN gene expression conformed to those previously seen in LP acclimated animals within 3 days of transfer to LP. Mean levels of expression for Per1-2 and Fbxl21 were nearly 2-fold higher in the LP15 than in the SP group. The expression of Vip was arrhythmic and unaffected by photoperiod, while, in contrast to rodents, Grp expression was not detectable within the sheep SCN. Expression of the circadian output gene Avp cycled robustly in all photoperiod groups with no detectable change in phasing. Overall these data suggest that synchronizing effects of light on SCN circadian organisation proceed similarly in ungulates and in rodents, despite differences in neuropeptide gene expression.

  6. The Genetic Architecture of Flowering Time and Photoperiod Sensitivity in Maize as Revealed by QTL Review and Meta Analysis

    Institute of Scientific and Technical Information of China (English)

    Jie Xu; Tingzhao Rong; Yaxi Liu; Jian Liu; Moju Cao; Jing Wang; Hai Lan; Yunbi Xu; Yanli Lu; Guangtang Pan

    2012-01-01

    The control of flowering is not only important for reproduction,but also plays a key role in the processes of domestication and adaptation.To reveal the genetic architecture for flowering time and photoperiod sensitivity,a comprehensive evaluation of the relevant literature was performed and followed by meta analysis.A total of 25 synthetic consensus quantitative trait loci (QTL) and four hot-spot genomic regions were identified for photoperiod sensitivity including 11 genes related to photoperiod response or flower morphogenesis and development.Besides,a comparative analysis of the QTL for flowering time and photoperiod sensitivity highlighted the regions containing shared and unique QTL for the two traits.Candidate genes associated with maize flowering were identified through integrated analysis of the homologous genes for flowering time in plants and the consensus QTL regions for photoperiod sensitivity in maize (Zea mays L.).Our results suggest that the combination of literature review,meta-analysis and homologous blast is an efficient approach to identify new candidate genes and create a global view of the genetic architecture for maize photoperiodic flowering.Sequences of candidate genes can be used to develop molecular markers for various models of marker-assisted selection,such as marker-assisted recurrent selection and genomic selection that can contribute significantly to crop environmental adaptation.

  7. Association analysis of photoperiodic flowering time genes in west and central African sorghum [Sorghum bicolor (L. Moench

    Directory of Open Access Journals (Sweden)

    Bhosale Sankalp U

    2012-03-01

    Full Text Available Abstract Background Photoperiod-sensitive flowering is a key adaptive trait for sorghum (Sorghum bicolor in West and Central Africa. In this study we performed an association analysis to investigate the effect of polymorphisms within the genes putatively related to variation in flowering time on photoperiod-sensitive flowering in sorghum. For this purpose a genetically characterized panel of 219 sorghum accessions from West and Central Africa was evaluated for their photoperiod response index (PRI based on two sowing dates under field conditions. Results Sorghum accessions used in our study were genotyped for single nucleotide polymorphisms (SNPs in six genes putatively involved in the photoperiodic control of flowering time. Applying a mixed model approach and previously-determined population structure parameters to these candidate genes, we found significant associations between several SNPs with PRI for the genes CRYPTOCHROME 1 (CRY1-b1 and GIGANTEA (GI. Conclusions The negative values of Tajima's D, found for the genes of our study, suggested that purifying selection has acted on genes involved in photoperiodic control of flowering time in sorghum. The SNP markers of our study that showed significant associations with PRI can be used to create functional markers to serve as important tools for marker-assisted selection of photoperiod-sensitive cultivars in sorghum.

  8. Effects of Photoperiod Extension on Clock Gene and Neuropeptide RNA Expression in the SCN of the Soay Sheep

    Science.gov (United States)

    Dardente, Hugues; Wyse, Cathy A.; Lincoln, Gerald A.; Wagner, Gabriela C.; Hazlerigg, David G.

    2016-01-01

    In mammals, changing daylength (photoperiod) is the main synchronizer of seasonal functions. The photoperiodic information is transmitted through the retino-hypothalamic tract to the suprachiasmatic nuclei (SCN), site of the master circadian clock. To investigate effects of day length change on the sheep SCN, we used in-situ hybridization to assess the daily temporal organization of expression of circadian clock genes (Per1, Per2, Bmal1 and Fbxl21) and neuropeptides (Vip, Grp and Avp) in animals acclimated to a short photoperiod (SP; 8h of light) and at 3 or 15 days following transfer to a long photoperiod (LP3, LP15, respectively; 16h of light), achieved by an acute 8-h delay of lights off. We found that waveforms of SCN gene expression conformed to those previously seen in LP acclimated animals within 3 days of transfer to LP. Mean levels of expression for Per1-2 and Fbxl21 were nearly 2-fold higher in the LP15 than in the SP group. The expression of Vip was arrhythmic and unaffected by photoperiod, while, in contrast to rodents, Grp expression was not detectable within the sheep SCN. Expression of the circadian output gene Avp cycled robustly in all photoperiod groups with no detectable change in phasing. Overall these data suggest that synchronizing effects of light on SCN circadian organisation proceed similarly in ungulates and in rodents, despite differences in neuropeptide gene expression. PMID:27458725

  9. Trickle water and feeding system in plant culture and light-dark cycle effects on plant growth

    Science.gov (United States)

    Takano, T.; Inada, K.; Takanashi, J.

    Rockwool, as an inert medium covered or bagged with polyethylene film, can be effectively used for plant culture in space station. The most important machine is the pump adjusting the dripping rate in the feeding system. Hydro-aeroponics may be adaptable to a space laboratory. The shortening of the light-dark cycles inhibits plant growth and induces an abnormal morphogenesis. A photoperiod of 12-hr-dark may be needed for plant growth.

  10. Feeding Your Newborn

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Feeding Your Newborn KidsHealth > For Parents > Feeding Your Newborn ... giving up the breast. previous continue About Formula Feeding Commercially prepared infant formula is a nutritious alternative ...

  11. Research progress of photoperiod regulated genes on flowering time in rice.

    Science.gov (United States)

    Deyan, Kong; Shoujun, Chen; Liguo, Zhou; Huan, Gao; Lijun, Luo; Zaochang, Liu

    2016-06-20

    Rice flowering regulation is an extremely complex process, which is controlled by genetic factors and external environment. Photoperiodic regulatory pathway is pivotal to control flowering in rice, in which florigen genes Hd3a and RTF1 are at the core and they are regulated by upstream Hd1-dependent, Ehd1-dependent, as well as both Hd1- and Ehd1-independent pathways. The three pathways bring a variety of light signal information together to Hd3a and RTF1 for further integration, and then transmit the signals in the form of florigen to the downstream flowering related genes. In this review, we summarize the research progress of photoperiod regulated genes on flowering time in rice, including the photoreceptors and circadian rhythm genes, the florigens, its upstream, downstream and interacting genes. We hope to provide a reference for in-depth study of rice flowering regulation.

  12. Photoperiodic stress on nitrite production by splenic macrophages in fresh-water snake Natrix piscator

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    Tripathi Manish Kumar

    2012-05-01

    Full Text Available Changes in day length enhance or suppress component of immune function in individuals of several species. The purpose of the present experiment was to study the role of photoperiodic manipulation on the nitric oxide production by splenic macrophages in the fresh-water snake, Natrix piscator. To study effect of photoperiod, animals were subjected to 24 hour continuous light and continuous dark for 30 days. Animals kept in natural day length served as control. At termination of experiments, animals were sacrificed, and spleen was excised. Macrophages were incubated for 24 hours and nitric oxide production was measured by measuring the nitrite concentration. Nitrite production was significantly decreased to the cultures obtained from the animals kept under continuous light. No change in nitrite concentration was found in animals kept under continuous dark, when compared to the animals kept under natural day length. The possible role of decreased melatonin synthesis in light is suggested to decrease the nitric oxide production.

  13. Effects of photoperiod on reproduction of Siamese fighting fish Betta splendens

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    Luiz Gustavo Giannecchini

    2012-04-01

    Full Text Available This study investigated the effect of different photoperiods (24 h of light (L:0 h of darkness (D; 20L:4D; 16L:8D; 12L:12D; and 8L:16D on the reproduction and growth of Betta splendens. The results showed that spawning frequency was significantly higher in couples reared under 16L:8D and 12L:12D, in comparison with other treatments. The highest number of eggs per spawn was obtained under 16L:8D (544.76±375.23 and 12L:12D (471.13±261.52, and the lowest values were detected for 24L:0D (128.55±58.14 and 20L:4D (187.87±103.84. Fertility and fecundity also showed significantly higher average values in 16L:8D and 12L:12D when compared with 24L:0D and 20L:4D treatments. Egg volume and perivitelline space were significantly higher in 24L:0D treatments that showed the lowest numbers of eggs per spawn, while the vitelline volume did not show significant differences. Other variables such as breeders weight gain and condition factor (K were not statistically different. Moreover, the final length varies according to photoperiod and gender. These results demonstrated a key role for the photoperiod upon B. splendens reproduction. The best reproductive performance is achieved under the photoperiods that best approached those that occur in spring and summer (16L:8D and 12L:12D, coinciding with their best seasons for reproduction.

  14. Effects of photoperiod on body mass, thermogenesis and body composition in Eothenomys miletus during cold exposure

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    Wan-long Zhu

    2012-05-01

    Full Text Available Many small mammals respond to seasonal changes in photoperiod by altering body mass and adiposity. These animals may provide valuable models for understanding the regulation of energy balance. In present study, we examined the effect on body mass, rest metabolic rate, food intake and body composition in cold-acclimated (5 °C in Eothenomys miletus by transferring them from a short (SD, 8h :16h L: D to long day photoperiod (LD, 16h: 8h L:D. During the first 4 weeks of exposure to SD, E. miletus decreased body mass. After the next 4 weeks of exposure to LD, which the average difference between body masses of LD and SD voles was 4.76 g. This 14.74% increase in body mass reflected significant increases in absolute amounts of body components, including wet carcass mass, dry carcass mass and body fat mass. After correcting body composition and organ morphology data for the differences in body mass, only livers, kidney, and small intestine were enlarged due to photoperiod treatment during cold exposure. E. miletus increased RMR and energy intake exposure to LD, but maintained a stable level to SD after 28 days. Serum leptin levels were positively correlated with body mass, body fat mass, RMR as well as energy intake. All of the results indicated that E. miletus may provide an attractive novel animal model for investigation of the regulation of body mass and energy balance at organism levels. Leptin is potentially involved in the photoperiod induced body mass regulation and thermogenesis in E. miletus during cold exposure.

  15. Effect of photoperiod on the feline adipose transcriptome as assessed by RNA sequencing

    OpenAIRE

    Mori, Akihiro; Kappen, Kelly L; Dilger, Anna C; Swanson, Kelly S.

    2014-01-01

    Background Photoperiod is known to cause physiological changes in seasonal mammals, including changes in body weight, physical activity, reproductive status, and adipose tissue gene expression in several species. The objective of this study was to determine the effects of day length on the adipose transcriptome of cats as assessed by RNA sequencing. Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exp...

  16. Photoperiod-dependent modulation of cardiac excitation contraction coupling in the Siberian hamster.

    Science.gov (United States)

    Dibb, K M; Hagarty, C L; Loudon, A S I; Trafford, A W

    2005-03-01

    In mammals, changes in photoperiod regulate a diverse array of physiological and behavioral processes, an example of which in the Siberian hamster (Phodopus sungorus) is the expression of bouts of daily torpor following prolonged exposure to a short photoperiod. During torpor, body temperature drops dramatically; however, unlike in nonhibernating or nontorpid species, the myocardium retains the ability to contract and is resistant to the development of arrhythmias. In the present study, we sought to determine whether exposure to a short photoperiod results in alterations to cardiac excitation-contraction coupling, thus potentially enabling the heart to survive periods of low temperature during torpor. Experiments were performed on single ventricular myocytes freshly isolated from the hearts of Siberian hamsters that had been exposed to either 12 wk of short-day lengths (SD) or 12 wk of long-day lengths (LD). In SD-acclimated animals, the amplitude of the systolic Ca(2+) transient was increased (e.g., from 142 +/- 17 nmol/l in LD to 229 +/- 31 nmol/l in SD at 4 Hz; P < 0.001). The increased Ca(2+) transient amplitude in the SD-acclimated animals was not associated with any change in the shape or duration of the action potential. However, sarcoplasmic reticulum Ca(2+) content measured after current-clamp stimulation was increased in the SD-acclimated animals (at 4 Hz, 110 +/- 5 vs. 141 +/- 15 mumol/l, P < 0.05). We propose that short photoperiods reprogram the function of the cardiac sarcoplasmic reticulum, resulting in an increased Ca(2+) content, and that this may be a necessary precursor for maintenance of cardiac function during winter torpor.

  17. Photoperiodic regulation of satiety mediating neuropeptides in the brainstem of the seasonal Siberian hamster (Phodopus sungorus).

    Science.gov (United States)

    Helwig, Michael; Archer, Zoë A; Heldmaier, Gerhard; Tups, Alexander; Mercer, Julian G; Klingenspor, Martin

    2009-07-01

    Central regulation of energy balance in seasonal mammals such as the Siberian hamster is dependent on the precise integration of short-term satiety information arising from the gastrointestinal tract with long-term signals on the status of available energy reserves (e.g. leptin) and prevailing photoperiod. Within the central nervous system, the brainstem nucleus of the solitary tract (NTS) and the parabrachial nucleus (PBN) are major relay nuclei that transmit information from the gastrointestinal tract to higher forebrain centres. We extended studies on the seasonal programming of the hypothalamus to examine the effect of the photoperiod on neuropeptidergic circuitries of this gut-brain axis. In the NTS and PBN we performed gene expression and immunoreactivity (-ir) studies on selected satiety-related neuropeptides and receptors: alpha-melanocyte stimulating hormone, melanocortin-3 receptor, melanocortin-4 receptor (MC4-R), growth hormone secretagogue-receptor, cocaine- and amphetamine-regulated transcript, preproglucagon (PPG), glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY, galanin, neurotensin, and corticotrophin releasing hormone (CRH). Gene expression of PPG and MC4-R, and -ir of CCK and GLP-1, in the NTS were up-regulated after 14 weeks in long-day photoperiod (16 h light:8 h dark) compared to short-days (8 h light:16 h dark), whereas CRH-ir and NT-ir were increased in short-days within the PBN. We suggest that brainstem neuroendocrine mechanisms contribute to the long-term regulation of body mass in the Siberian hamster by a photoperiod-related modulation of satiety signalling.

  18. Pubertal growth of the medial amygdala delayed by short photoperiods in the Siberian hamster, Phodopus sungorus.

    Science.gov (United States)

    Cooke, Bradley M; Jordan, Cynthia L; Breedlove, S Marc

    2007-09-01

    We investigated whether puberty influences the morphology of the medial nucleus of the amygdala (MeA) by comparing Siberian hamsters (Phodopus sungorus) that had been raised from birth in either long day (LD; 16:8 h light:dark) or short day (SD; 8:16) photoperiods. Hamsters were sacrificed at 42-49 days of age, at which point all LD hamsters were reproductively mature, as evidenced by adult-like testes weights (mean: 657 mg). In contrast, the testes weights of the SD hamsters were low (mean: 31 mg), indicating that the SD photoperiod had delayed puberty. The regional volume and mean soma size of the four MeA subnuclei was estimated bilaterally by stereological procedures. In the posterior dorsal and ventral MeA subnuclei, regional volume was 22-25% larger, and mean soma size 18% larger, in LD males than SD males. Unbiased cell counts in the posterior dorsal MeA showed that LD and SD hamsters have equivalent neuron numbers. In the anterior MeA subnuclei, regional volumes and soma sizes from LD and SD hamsters were equivalent. Additionally, the regional volume of the posteroventral subnucleus was larger in the right hemisphere than the left, but this laterality did not respond to photoperiod manipulation. These results suggest that the extant neurons within the posterior MeA, a steroid-sensitive nucleus implicated in socio-sexual behavior, grow in response to the elevated levels of circulating androgen accompanying puberty, and that photoperiodic regulation of puberty affects morphological maturation of this nucleus.

  19. QTL Identification of the Insensitive Response to Photoperiod and Temperature in Soybean by Association Mapping

    Institute of Scientific and Technical Information of China (English)

    ZUO Qiao-mei; WEN Zi-xiang; ZHANG Shu-yun; HOU Jin-feng; GAI Jun-yi; YU De-yue; XING Han

    2013-01-01

    The insensitive response to photoperiod and temperature is an important quantitative trait for soybean in wide adaptation breeding. The natural variation in response to photoperiod and temperature was detected using 275 accessions of soybean [Glycine max (L.) Merrill] from China. Genome-wide association mapping, based on population structure analysis, was carried out using 118 SSR markers by the TASSEL GLM (general linear model) program. Nine SSR markers (P<0.01) were associated with the value of the response to photoperiod and temperature (VRPT) caused by days to flowering (DF), among which, Satt308 (LG M), Satt150 (LG M) and Satt440 (LG I), were identified in both 2006 and 2007. Twelve SSR markers (P<0.01) were associated with VRPT caused by days to maturity (DM), among which three markers, Satt387 (LG N), Satt307 (LG C2) and AW310961 (LG J), were detected in both 2006 and 2007. In addition, a total of 20 elite alleles were screened out over 2006 and 2007 for being associated with an insensitive response to photoperiod and temperature (IRPT) caused by DF and a total of seven different elite alleles were screened out for being associated with IRPT caused by DM. Among these elite alleles, five alleles, Satt150-244, Satt308-164, Satt308-206, Satt440-176, and Satt440-206, were associated with IRPT caused by DF and were identified in both years, but only one allele, Satt307-170, was identified as being associated with an IRPT caused by DM. Based on these elite alleles, a set of typical accessions were screened out. The result about the genetic basis of IRPT is meaningful for soybean wide adaption breeding.

  20. Photoperiodic and thermosensory pathways interact through CONSTANS to promote flowering at high temperature under short days.

    Science.gov (United States)

    Fernández, Virginia; Takahashi, Yasuyuki; Le Gourrierec, José; Coupland, George

    2016-06-01

    Plants detect changes in day length to induce seasonal patterns of flowering. The photoperiodic pathway accelerates the flowering of Arabidopsis thaliana under long days (LDs) whereas it is inactive under short days (SDs), resulting in delayed flowering. This delay is overcome by exposure of plants to high temperature (27°C) under SDs (27°C-SD). Previously, the high-temperature flowering response was proposed to involve either the impaired activity of MADS-box transcription factor (TF) floral repressors or PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) TF-mediated activation of FLOWERING LOCUS T (FT), which encodes the output signal of the photoperiodic pathway. We integrate these observations by studying several PIFs, the MADS-box SHORT VEGETATIVE PHASE (SVP) and the photoperiodic pathway under 27°C-SD. We find that the mRNAs of FT and its paralogue TWIN SISTER OF FT (TSF) are increased at dusk under 27°C-SD compared with 21°C-SD, and that this requires PIF4 and PIF5 as well as CONSTANS (CO), a TF that promotes flowering under LDs. The CO and PIF4 proteins are present at dusk under 27°C-SD, and they physically interact. Although Col-0 plants flower at similar times under 27°C-SD and 21°C-LD the expression level of FT is approximately 10-fold higher under 21°C-LD, suggesting that responsiveness to FT is also increased under 27°C-SD, perhaps as a result of the reduced activity of SVP in the meristem. Accordingly, only svp-41 ft-10 tsf-1 plants flowered at the same time under 21°C-SD and 27°C-SD. Thus, we propose that under non-inductive SDs, elevated temperatures increase the activity and sensitize the response to the photoperiod pathway.

  1. Photoperiodic regulation of flowering time through periodic histone deacetylation of the florigen gene FT.

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    Xiaofeng Gu

    2013-09-01

    Full Text Available The developmental transition from a vegetative to a reproductive phase (i.e., flowering is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT, widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO, specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.

  2. Photoperiodic regulation of flowering time through periodic histone deacetylation of the florigen gene FT.

    Science.gov (United States)

    Gu, Xiaofeng; Wang, Yizhong; He, Yuehui

    2013-09-01

    The developmental transition from a vegetative to a reproductive phase (i.e., flowering) is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT), widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO), specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC) complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.

  3. Germination of guatambu seeds subjected to two light regimes

    Directory of Open Access Journals (Sweden)

    Karina Guollo

    2015-09-01

    Full Text Available Guatambu (Aspidosperma parvifolium A. DC. is a species that faces extinction in different regions of Brazil. The aim of this study was to evaluate the influence of photoperiod on germination of guatambu seeds at 25°C. The statistical procedure used was factorial design with two factors. Factor A was seed lots (Mother tree A, B, and C and factor B was photoperiod (dark and 12 h of photoperiod. Guatambu seeds are not affected by photoperiod condition during the germination process.

  4. Circadian perinatal photoperiod has enduring effects on retinal dopamine and visual function.

    Science.gov (United States)

    Jackson, Chad R; Capozzi, Megan; Dai, Heng; McMahon, Douglas G

    2014-03-26

    Visual system development depends on neural activity, driven by intrinsic and light-sensitive mechanisms. Here, we examined the effects on retinal function due to exposure to summer- and winter-like circadian light cycles during development and adulthood. Retinal light responses, visual behaviors, dopamine content, retinal morphology, and gene expression were assessed in mice reared in seasonal photoperiods consisting of light/dark cycles of 8:16, 16:8, and 12:12 h, respectively. Mice exposed to short, winter-like, light cycles showed enduring deficits in photopic retinal light responses and visual contrast sensitivity, but only transient changes were observed for scotopic measures. Dopamine levels were significantly lower in short photoperiod mice, and dopaminergic agonist treatment rescued the photopic light response deficits. Tyrosine hydroxylase and Early Growth Response factor-1 mRNA expression were reduced in short photoperiod retinas. Therefore, seasonal light cycles experienced during retinal development and maturation have lasting influence on retinal and visual function, likely through developmental programming of retinal dopamine.

  5. Time interval from ovulation to extrusion in female bullfrog in different photoperiods

    Directory of Open Access Journals (Sweden)

    Claudio Angelo Agostinho

    2011-08-01

    Full Text Available It was analyzed in this work the influence of photoperiod on time interval from ovulation induction period to extrusion of ovocits in female bullfrogs (Lithobates catesbeianus. It was used 54 females reared from metamorphosis to 9 months of age under three photoperiods: dark time (DL 0:24, 16 hours of daylight (DL 16:8 and 12 hours of daylight (DL 12:12. Ovulation was induced by intramuscular application of two doses of LHRHa with 12 hours of interval between the injections. After 10, 25, 28, 31, 34 and 37 hours from the first hormone injection, 10-gram samples (3,000 eggs were extracted from each female at each time interval and fertilized. Egg hatching rate was checked in each sample 72 hours after fertilization. Analysis of variance showed a significant effect of extrusion delay and the interaction between photoperiod and this delay. Extrusion should be carried out 33, 24 and 26 hours after the first hormone dosage in females reared in environments without light, with 12 hours of daylight and with 16 hours of daylight, respectively, to obtain the maximum fertilization rate.

  6. Selection and Characterization of a Novel Photoperiod-Sensitive Male Sterile Line in Upland Cotton

    Institute of Scientific and Technical Information of China (English)

    Jianhui Ma; Hengling Wei; Ji Liu; Meizhen Song; Chaoyou Pang; Long Wang; Wenxiang Zhang

    2013-01-01

    Upland cotton (Gossypium hirsutum L.) shows strong heterosis.However,heterosis is not widely utilized owing to the high cost of hybrid seed production.Creation of a photoperiod-sensitive genetic male sterile line could substantially reduce the cost of hybrid seed production in upland cotton.Such a mutant with virescent marker was found by space mutation in near-earth orbit and its traits had been stable after 4 years of selection in Anyang and Sanya,China.This mutant was fertile with an 11-12.5 h photoperiod when the temperature was higher than 21.5 C and was sterile with a 13-14.5 h photoperiod.Genetic analysis indicated that both traits were controlled by a single recessive gene or two closely linked genes.Also,the cytological observations,and transcriptome profiling analysis showed that the degradation of pollen grain cytoplasm should be the primary reason why the mutant line were male sterile under long-day conditions.

  7. Effect of temperature and photoperiod on maturation of Cephalothrix hongkongiensis (Nemertea: Palaeonemertea)

    Science.gov (United States)

    Li, Yingdong; Song, Xiaoyue; Zhang, Shanshan; Zhu, Lin; Sun, Shichun

    2014-07-01

    The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4°C and 6°C showed no growth or gonadal development, and all died within 109 days. At 8°C and 12°C, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28°C showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature (16°C), photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis.

  8. Photoperiodic regulation of androgen receptor and steroid receptor coactivator-1 in Siberian hamster brain.

    Science.gov (United States)

    Tetel, Marc J; Ungar, Todd C; Hassan, Brett; Bittman, Eric L

    2004-11-24

    Seasonal changes in the neuroendocrine actions of gonadal steroid hormones are triggered by fluctuations in daylength. The mechanisms responsible for photoperiodic influences upon the feedback and behavioral effects of testosterone in Siberian hamsters are poorly understood. We hypothesized that daylength regulates the expression of androgen receptor (AR) and/or steroid receptor coactivator-1 (SRC-1) in specific forebrain regions. Hamsters were castrated and implanted with either oil-filled capsules or low doses of testosterone; half of the animals remained in 16L/8D and the rest were kept in 10L/14D for the ensuing 70 days. The number of AR-immunoreactive (AR-ir) cells was regulated by testosterone in medial amygdala and caudal arcuate, and by photoperiod in the medial preoptic nucleus and the posterodorsal medial amygdala. A significant interaction between photoperiod and androgen treatment was found in medial preoptic nucleus and posterodorsal medial amygdala. The molecular weight and distribution of SRC-1 were similar to reports in other rodent species, and short days reduced the number of SRC-1-ir cells in posteromedial bed nucleus of the stria terminalis (BNST) and posterodorsal medial amygdala. A significant interaction between androgen treatment and daylength in regulation of SRC-1-ir was found in anterior medial amygdala. The present results indicate that daylength-induced fluctuations in SRC-1 and AR expression may contribute to seasonally changing effects of testosterone.

  9. Perception of photoperiod in individual buds of mature trees regulates leaf-out.

    Science.gov (United States)

    Zohner, Constantin M; Renner, Susanne S

    2015-12-01

    Experimental data on the perception of day length and temperature in dormant temperate zone trees are surprisingly scarce. In order to investigate when and where these environmental signals are perceived, we carried out bagging experiments in which buds on branches of Fagus sylvatica, Aesculus hippocastanum and Picea abies trees were exposed to natural light increase or kept at constant 8-h days from December until June. Parallel experiments used twigs cut from the same trees, harvesting treated and control twigs seven times and then exposing them to 8- or 16-h days in a glasshouse. Under 8-h days, budburst in Fagus outdoors was delayed by 41 d and in Aesculus by 4 d; in Picea, day length had no effect. Buds on nearby branches reacted autonomously, and leaf primordia only reacted to light cues in late dormancy after accumulating warm days. Experiments applying different wavelength spectra and high-resolution spectrometry to buds indicate a phytochrome-mediated photoperiod control. By demonstrating local photoperiodic control of buds, revealing the time when these signals are perceived, and showing the interplay between photoperiod and chilling, this study contributes to improved modelling of the impact of climate warming on photosensitive species.

  10. Influence of photoperiodism on the spatio-temporal accumulation of steviol glycosides in Stevia rebaudiana (Bertoni).

    Science.gov (United States)

    Ceunen, Stijn; Geuns, Jan M C

    2013-01-01

    The effect of photoperiodism on steviol glycoside (SVgly) accumulation was investigated in Stevia rebaudiana. Topped plants were cultivated to develop new branches under a 16h or 8h photoperiod. During different ontogenetic phases, leaves, stems, lateral shoots, roots and reproductive organs were collected and analysed for nine SVglys. Long-day (LD) conditions prolonged vegetative growth, significantly increasing leaf biomass and total SVgly content. In both photoperiods, declines in SVglys were observed during reproductive development, occurring mainly in mature leaves under LDs or young leaves under SDs. When lateral shoots were included in plants under LDs, total leaf and SVgly yield per branch significantly increased, indicating a harvest during flowering is possible. The ratio of rebaudioside A (Reb A) to stevioside (ST) amounts was influenced by ontogeny and daylength, with larger ratios during vegetative growth under SDs. Linear correlations were observed between dry matter and total SVglys and between the major SVglys individually. Minor SVglys showed larger fluctuations, especially under SDs. Under LDs, the Reb A to ST ratio was inversely correlated with both leaf dry matter and total SVglys. The highly dynamic nature of the observed patterns suggests a complex regulation of SVgly metabolism on molecular and biochemical level.

  11. Enabling photoperiodic control of flowering by timely chromatin silencing of the florigen gene.

    Science.gov (United States)

    He, Yuehui

    2015-01-01

    Many plants synchronize their flowering times with changing seasons to maximize reproductive success. A key seasonal cue is the change in day length (photoperiod), that induces the production of a systemic flowering signaling molecule called florigen. A major florigen component is FLOWERING LOCUS T (FT) or its orthologs. In the long-day plant Arabidopsis thaliana, FT expression is well known to be activated by the photoperiod pathway output specifically near dusk in long days; however, underappreciated is the importance of FT silencing at other times of the day, in enabling Arabidopsis to respond only to long days in flowering. We have recently reported that a plant-specific chromatin-silencing complex called EMF1c represses FT expression at times other than around dusk in long days to prevent its temporal ectopic expression from "spoiling" the long-day floral induction in Arabidopsis. Here I further discuss in other day-length sensitive plants the potential involvement of a chromatin mechanism similar to the Arabidopsis EMF1c-mediated silencing, in repressing the expression of FT orthologs to enable diverse photoperiodic control of flowering.

  12. Supply regimes in fisheries

    DEFF Research Database (Denmark)

    Nielsen, Max

    2006-01-01

    Supply in fisheries is traditionally known for its backward bending nature, owing to externalities in production. Such a supply regime, however, exist only for pure open access fisheries. Since most fisheries worldwide are neither pure open access, nor optimally managed, rather between the extremes......-economic supply model with mesh sizes is developed. It is found that in the presence of realistic management schemes, the supply curves are close to vertical in the relevant range. Also, the supply curve under open access with mesh size limitations is almost vertical in the relevant range, owing to constant...... recruitment. The implications are that the effects on supply following from e.g. trade liberalisation and reductions of subsidies are small in several and probably most fisheries worldwide. Keywords: backward-bending supply, regulated open access, regulated restricted access, mesh size regulation, Beverton...

  13. Gibberellins and stem growth as related to photoperiod Silene armeria L

    Energy Technology Data Exchange (ETDEWEB)

    Talon, M.; Zeevaart, J.A.D. (Michigan State Univ., East Lansing (USA))

    1990-04-01

    Stem growth and flowering in the long-day plant Silene armeria L. are induced by exposure to a minimum of 3 to 6 long days (LD). Stem growth continues in subsequent short days (SD), albeit at a reduced rate. The growth retardant tetcyclacis inhibited stem elongation induced by LD, but had no effect on flowering. This indicates that photoperiodic control of stem growth in Silene is mediated by gibberellins (GA). The objective of this study was to analyze the effects of photoperiod on the levels and distribution of endogenous GAs in Silene and to determine the nature of the photoperiodic after-effect on stem growth in this plant. The GAs identified in extracts from Silene by full-scan combined gas chromatography-mass spectrometry are members of the early 13-hydroxylation pathway. All of these GAs were present in plants under SD as well as under LD conditions. The GA{sub 53} level was highest in plants in SD, and decreased in plants transferred to LD conditions. By contrast, GA{sub 19}, GA{sub 20}, and GA{sub 1} initially increased in plants transferred to LD, and then declined. Likewise, when Silene plants were returned from LD to SD, there was an increase in GA{sub 53}, and a decrease in GA{sub 19}, GA{sub 20}, and GA{sub 1} which ultimately reached levels similar to those found in plants kept in SD. Thus, measurements of GA levels in whole shoots of Silene as well as in individual parts of the plant suggest that the photoperiod modulates GA metabolism mainly through the rate of conversion of GA{sub 53}. As a result of LD induction, GA{sub 1} accumulates at its highest level in shoot tips which, in turn, results in stem elongation. In addition, LD also appear to increase the sensitivity of the tissue to GA, and this effect is presumably responsible for the photoperiodic after-effect on stem elongation in Silene.

  14. Photoperiodic diapause under the control of circadian clock genes in an insect

    Directory of Open Access Journals (Sweden)

    Ikeno Tomoko

    2010-09-01

    Full Text Available Abstract Background Most organisms have evolved a circadian clock in order to anticipate daily environmental changes and many of these organisms are also capable of sophisticated measurement of daylength (photoperiodism that is used to regulate seasonal events such as diapause, migration and polymorphism. It has been generally accepted that the same elements are involved in both circadian (daily and seasonal (annual rhythms because both rely upon daily light-dark cycles. However, as reasonable as this sounds, there remains no conclusive evidence of such a molecular machinery in insects. We have approached this issue by using RNA interference (RNAi in Riptortus pedestris. Results The cuticle deposition rhythm exhibited the major properties of circadian rhythms, indicating that the rhythm is regulated by a circadian clock. RNAi directed against the circadian clock genes of period and cycle, which are negative and positive regulators in the circadian clock, respectively, disrupted the cuticle deposition rhythm and distinct cuticle layers were produced by these RNAi. Simultaneously, period RNAi caused the insect to avert diapause under a diapause-inducing photoperiod whereas cycle RNAi induced diapause under a diapause-averting photoperiod. The expression patterns of juvenile hormone-regulated genes and the application of juvenile hormone analogue suggested that neither ovarian development itself nor a downstream cascade of juvenile hormone secretion, were disturbed by period and cycle RNAi. Conclusions This study revealed that the circadian clock genes are crucial not only for daily rhythms but also for photoperiodic diapause. RNAi directed against period and cycle had opposite effects not only in the circadian cuticle deposition rhythm but also in the photoperiodic diapause. These RNAi also had opposite effects on juvenile hormone-regulated gene expression. It is still possible that the circadian clock genes pleiotropically affect ovarian

  15. Light-dark cycle and feeding time differentially entrains the gut molecular clock of the goldfish (Carassius auratus).

    Science.gov (United States)

    Nisembaum, Laura G; Velarde, Elena; Tinoco, Ana B; Azpeleta, Clara; de Pedro, Nuria; Alonso-Gómez, Angel L; Delgado, María J; Isorna, Esther

    2012-07-01

    The aim of the present study was to investigate how photocycle and feeding-time cues regulate the daily expression of Per1a, Per2a, Per3, and Cry3 in the goldfish hindgut. For this purpose, we studied the daily rhythmicity of these genes in fish maintained under different lighting conditions and under different feeding regimes (scheduled or not). We also studied whether the timing of just one meal is able to reset the hindgut molecular clock. In a first experiment, randomly fed fish were divided into four groups and kept under different light conditions for 30 d: 12 h light and 12 h dark (12L:12D), an inverted photoperiod (12D:12L), constant darkness (24D), and constant light (24L). In a second study, fish maintained under 24L were divided into four groups fed at different time points for 35 d: (1) fish scheduled-fed once a day (at 10:00 h); (2) fish fed with a 12-h shifted schedule (at 22:00 h), (3) fish fed at 10:00 h throughout the experiment, except the last day when fed at 22:00 h; and (4) a randomly fed group of fish. Fish were sacrificed every 6 h throughout a 24-h cycle. In both experiments, gPer1a, gPer2a, gPer3, and gCry3 transcripts were quantified using Real Time-qPCR in the hindgut. Results show the clock genes gPer1a, gPer2a, and gCry3 are synchronized by both zeitgebers, the photocycle and feeding regime, in goldfish hindgut. Moreover, such clock genes anticipate light-on and food delivery, when these cues appear in a cyclic manner. In the absence of both zeitgebers, gCry3 and gPer2a rhythmicity disappeared. In contrast, the gPer1 rhythm was maintained under 24L and random feeding conditions, but not always, suggesting that food when randomly supplied is able to reset the clock depending on other factors, such as the energetic and metabolic conditions of the fish. The expression of gPer2a was not activated during the light phase of the cycle, suggesting the hindgut of goldfish is a non-direct photosensitive organ. In contrast to the other three genes

  16. Spermatogenesis in the turkey (Meleagris gallopavo): quantitative approach in immature and adult males subjected to various photoperiods.

    Science.gov (United States)

    Noirault, Jérôme; Brillard, Jean-Pierre; Bakst, Murray R

    2006-03-01

    The objectives of this study were to identify and quantitate the germ cell populations of the testes in sexually mature male turkeys (Trial 1), determine the duration of meiosis based on BrdU labeling and stereological analyses (Trial 2), and examine the impact of various photoperiods on germinal and somatic cell populations in immature and adult males (Trial 3). In Trial 1, both testes within a male had similar stereological components (P>0.05) for all parameters analyzed. In Trial 2, the duration of Type-1 spermatocytes and round spermatids in turkeys lasted 4.5+/-0.5 and 2.0+/-0.5 days, respectively. In Trial 3, the short photoperiod (7L:17D) delayed testicular growth (in the stereological parameters analyzed). In contrast, the effect of a moderately short photoperiod (10.5L:13.5D) was comparable to the effect of a long (14L:10D) or increasing photoperiod (7L:17D to 14L:10D) on the stereological parameters examined. With the exception of the short photoperiod, all other photoperiods used in this study induced comparable early testicular maturation, with maximum testis weight at 29-35 weeks of age. As the males got older, there was a progressive, linear decline in testis weight through 60 weeks, at which time there were no significant differences among photoperiods. In conclusion, the duration of meiosis in the turkey was similar to that observed in the fowl and guinea-fowl. The existence of a threshold of photosensitivity to gonad stimulation in male turkeys is suggested to be between 7.0 and 10.5 h of light.

  17. The effect of the photoperiod on the level of endogenous growth regulators in pine (Pinus silvestris L. seedlings

    Directory of Open Access Journals (Sweden)

    Krystyna Kriesel

    2014-02-01

    Full Text Available The investigations were performed on pine seedlings growing under 12, 16 and 20 hour photoperiods. In 4 succesive stages of seedling development i.e. after 2, 12, 18 and 30 weeks of culture morphological characters of the seedlings were measured and the levels of auxins-, gibberellins-, cytokininsand abscisic acid-like inhibitor were determined. The intensity of growth and development of juvenile leaves, needles and of the shoot was the lowest in plants growing under 12 hour photoperiod conditions. As the length of the photoperiod increased so did the intensity of these processes. Under the 12 hour photoperiod the development of scale leaves, axillary buds and the formation of the terminal bud started earliest. This process reached completion under the 12 hour photoperiod and the bud remained in a state of dormancy. Seedlings growing under the 12 hour photoperiod were characterized by a low level of stimulators, and at the same time by a high level of inhibitors. On the other hand in seedlings grown at 16 and 20 hour photoperiods the content of stimulators was higher and that of inhibitors lower. A high intensity of growth and development processes was correlated with a high level of stimulators while a high level of inhibitors was correlated with a low intensity of these processes.The obtained results suggest the participation of gibberellins and cytokinins in the processes of regulation of the initiation of scale leaves and axillary buds, and the participation of these hormones and of abscisic acid in the regulation of needle elongation.

  18. A Microarray-Based Analysis Reveals that a Short Photoperiod Promotes Hair Growth in the Arbas Cashmere Goat.

    Directory of Open Access Journals (Sweden)

    Bin Liu

    Full Text Available Many animals exhibit different behaviors in different seasons. The photoperiod can have effects on migration, breeding, fur growth, and other processes. The cyclic growth of the fur and feathers of some species of mammals and birds, respectively, is stimulated by the photoperiod as a result of hormone-dependent regulation of the nervous system. To further examine this phenomenon, we evaluated the Arbas Cashmere goat (Capra hircus, a species that is often used in this type of research. The goats were exposed to an experimentally controlled short photoperiod to study the regulation of cyclic cashmere growth. Exposure to a short photoperiod extended the anagen phase of the Cashmere goat hair follicle to increase cashmere production. Assessments of tissue sections indicated that the short photoperiod significantly induced cashmere growth. This conclusion was supported by a comparison of the differences in gene expression between the short photoperiod and natural conditions using gene chip technology. Using the gene chip data, we identified genes that showed altered expression under the short photoperiod compared to natural conditions, and these genes were found to be involved in the biological processes of hair follicle growth, structural composition of the hair follicle, and the morphogenesis of the surrounding skin appendages. Knowledge about differences in the expression of these genes as well as their functions and periodic regulation patterns increases our understanding of Cashmere goat hair follicle growth. This study also provides preliminary data that may be useful for the development of an artificial method to improve cashmere production by controlling the light cycle, which has practical significance for livestock breeding.

  19. Potential uses of gut weed Enteromorpha spp. as a feed for herbivorous fish.

    Science.gov (United States)

    Anh, Nguyen Thi Ngoc; Hien, Tran Thi Thanh; Hai, Tran Ngoc

    2013-01-01

    Three separate experiments were performed to assess the potential use of gut weeds Enteromorpha spp. as a food source for herbivorous fish. The fresh or dried gut weeds were used as a direct feed to replace commercial feed in an alternative approach for feeding spotted seat (Scatophagus argus), red tilapia (Oreochromis sp.), and giant gourami (Osphronemus goramy) juveniles for 60 days, 45 days, and 56 days, respectively. Four feeding regimes were applied to triplicate tanks and fish was fed daily either commercial feed or gut weed: (1) single commercial feed everyday as a control treatment, (2) single gut weed daily and 2 alternative feeding regimes where (3) 1 day commercial feed and 1 consecutive day gut weed or and (4) 2 consecutive days gut weed. The results indicated that survival of experimental fish was not affected by the feeding treatments. Growth performance of the S. argus fed single gut weed was not significantly different from the control group (P>0.05). Growth rates of Oreochromis sp. and O. goramy in the alternative feeding treatments were comparable to the control treatment. Application of the combined feeding regimes, feed conversion ratio could be reduced from 26.1 to 57.8%. These results indicated that fresh and dried gut weed can be used as a feed to substitute commercial feed for herbivorous fish. Moreover, using gut weeds as a feed could improve water quality in the rearing tanks.

  20. Resilience of river flow regimes.

    Science.gov (United States)

    Botter, Gianluca; Basso, Stefano; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2013-08-06

    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. Here, we derive a measurable index embedding climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) that discriminates erratic regimes with enhanced intraseasonal streamflow variability from persistent regimes endowed with regular flow patterns. Theoretical and empirical data show that erratic hydrological regimes typical of rivers with low mean discharges are resilient in that they hold a reduced sensitivity to climate fluctuations. The distinction between erratic and persistent regimes provides a robust framework for characterizing the hydrology of freshwater ecosystems and improving water management strategies in times of global change.

  1. Effects of Hd2 in the presence of the photoperiod-insensitive functional allele of Hd1 in rice

    Directory of Open Access Journals (Sweden)

    Zhen-Hua Zhang

    2016-11-01

    Full Text Available The role of photoperiod sensitivity (PS of flowering genes have become well recognized in rice, whereas little attention has been drawn to the non-PS component of these genes, especially to their influence on gene-by-gene interactions. Rice populations in which the photoperiod-sensitive allele at Hd1 has become insensitive to photoperiod but continued to affect heading date (HD were used in this study to fine-map a quantitative trait locus (QTL for HD and analyze its genetic relationship to Hd1. The QTL was delimitated to a 96.3-kb region on the distal end of the long arm of chromosome 7. Sequence comparison revealed that this QTL is identical to Hd2. In the near-isogenic line (NIL populations analyzed, Hd1 and Hd2 were shown to be photoperiod insensitive and have pleiotropic effects for HD, plant height and yield traits. The two genes were found to largely act additively in regulating HD and yield traits. The results indicate that non-PS components of flowering genes involved in photoperiod response play an important role in controlling flowering time and grain yield in rice, which should allow breeders to better manipulate pleiotropic genes for balancing adaptability and high-yielding accumulation.

  2. Effect of exercise on photoperiod-regulated hypothalamic gene expression and peripheral hormones in the seasonal Dwarf Hamster Phodopus sungorus.

    Science.gov (United States)

    Petri, Ines; Dumbell, Rebecca; Scherbarth, Frank; Steinlechner, Stephan; Barrett, Perry

    2014-01-01

    The Siberian hamster (Phodopus sungorus) is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prevents or reverses body weight reduction is unknown, but one hypothesis is a reversal of short-day photoperiod induced gene expression changes in the hypothalamus that underpin body weight regulation. Alternatively, we postulate an exercise-related anabolic effect involving the growth hormone axis. To test these hypotheses we established photoperiod-running wheel experiments of 8 to 16 weeks duration assessing body weight, food intake, organ mass, lean and fat mass by magnetic resonance, circulating hormones FGF21 and insulin and hypothalamic gene expression. In response to running wheel activity, short-day housed hamsters increased body weight. Compared to short-day housed sedentary hamsters the body weight increase was accompanied by higher food intake, maintenance of tissue mass of key organs such as the liver, maintenance of lean and fat mass and hormonal profiles indicative of long day housed hamsters but there was no overall reversal of hypothalamic gene expression regulated by photoperiod. Therefore the mechanism by which activity induces body weight gain is likely to act largely independently of photoperiod regulated gene expression in the hypothalamus.

  3. Mutation in TERMINAL FLOWER1 reverses the photoperiodic requirement for flowering in the wild strawberry Fragaria vesca.

    Science.gov (United States)

    Koskela, Elli A; Mouhu, Katriina; Albani, Maria C; Kurokura, Takeshi; Rantanen, Marja; Sargent, Daniel J; Battey, Nicholas H; Coupland, George; Elomaa, Paula; Hytönen, Timo

    2012-07-01

    Photoperiodic flowering has been extensively studied in the annual short-day and long-day plants rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana), whereas less is known about the control of flowering in perennials. In the perennial wild strawberry, Fragaria vesca (Rosaceae), short-day and perpetual flowering long-day accessions occur. Genetic analyses showed that differences in their flowering responses are caused by a single gene, SEASONAL FLOWERING LOCUS, which may encode the F. vesca homolog of TERMINAL FLOWER1 (FvTFL1). We show through high-resolution mapping and transgenic approaches that FvTFL1 is the basis of this change in flowering behavior and demonstrate that FvTFL1 acts as a photoperiodically regulated repressor. In short-day F. vesca, long photoperiods activate FvTFL1 mRNA expression and short days suppress it, promoting flower induction. These seasonal cycles in FvTFL1 mRNA level confer seasonal cycling of vegetative and reproductive development. Mutations in FvTFL1 prevent long-day suppression of flowering, and the early flowering that then occurs under long days is dependent on the F. vesca homolog of FLOWERING LOCUS T. This photoperiodic response mechanism differs from those described in model annual plants. We suggest that this mechanism controls flowering within the perennial growth cycle in F. vesca and demonstrate that a change in a single gene reverses the photoperiodic requirements for flowering.

  4. Anticipating spring: wild populations of great tits (Parus major differ in expression of key genes for photoperiodic time measurement.

    Directory of Open Access Journals (Sweden)

    Nicole Perfito

    Full Text Available Measuring day length is critical for timing annual changes in physiology and behavior in many species. Recently, rapid changes in several photoperiodically-controlled genes following exposure to a single long day have been described. Components of this 'first day release' model have so far only been tested in highly domesticated species: quail, sheep, goats and rodents. Because artificial selection accompanying domestication acts on genes related to photoperiodicity, we must also study this phenomenon in wild organisms for it to be accepted as universal. In a songbird, the great tit (Parus major, we tested whether a these genes are involved in photoperiodic time measurement (PTM in a wild species, and b whether predictable species and population differences in expression patterns exist. Using quantitative RT-PCR, we compared gene expression after a single long day in male great tits from Sweden (57°42'N with that from a German (47°43'N population. Hypothalamic gene expression key for PTM changed only in the northern population, and occurred earlier after dawn during the single long day than demonstrated in quail; however, gonadotropins (secretion and synthesis were stimulated in both populations, albeit with different timing. Our data are the first to show acute changes in gene expression in response to photostimulation in any wild species not selected for study of photoperiodism. The pronounced differences in gene expression in response to a single long day between two populations raise exciting new questions about potential environmental selection on photoperiodic cue sensitivity.

  5. Photoperiodic regulation of melatonin membrane receptor (MT1R) expression and steroidogenesis in testis of adult golden hamster, Mesocricetus auratus.

    Science.gov (United States)

    Mukherjee, Arun; Haldar, Chandana

    2014-11-01

    Photoperiodic modulation of melatonin membrane receptor (MT1R) expression in testis has never been reported for any seasonal breeder. Thus, the aim of the present study was to investigate the expression dynamics of MT1R in testis and its interaction with testicular steroidogenesis in a long-day breeder, Mesocricetus auratus. Hamsters were exposed to different photoperiodic conditions i.e. critical- (CP; 12.5L:11.5D); short-day- (SD; 8L:16D) and long-day- (LD; 16L:8D) for 10 weeks wherein testicular steroidogenesis, local melatonin synthesis and the expression of MT1R were analyzed. SD induced melatonin suppressed testicular steroidogenesis as evident from regressed testicular histoarchitecture, decreased expression of AR, StAR, LH-R, P₄₅₀SCC and enzyme activities of 3β- and 17β-HSD. Differential photoperiodic regulation of MT1R expression in testis suggests its involvement in photoperiodic signal transduction for seasonal adjustment of reproduction. Increased S-NAT (Serotonin N-acetyl transferase) activity and local testicular melatonin under SD condition suggest an inhibitory effect of the local melatonergic system on testicular steroidogenesis. Completely opposite responses were recorded for all the parameters analyzed when hamsters were exposed to CP or LD conditions. In conclusion, we may suggest that photoperiod via regulating circulatory and local melatonin level as well as MT1R expression in testes fine tunes the steroidogenesis and thereby, the reproductive status of male golden hamster.

  6. The response of luteinizing hormone secretion to photoperiod is modified by the level of nutrition in female Mediterranean goats.

    Science.gov (United States)

    Zarazaga, L A; Celi, I; Guzmán, J L; Malpaux, B

    2011-06-01

    This paper reports the influence of nutrition on the photoperiodic control of luteinizing hormone (LH) secretion in female Mediterranean goats (i.e., goats from the Mediterranean area in general). Ovariectomized, oestradiol-treated goats were subjected to two consecutive intervals of 3 months of long days followed by 3 months of short days (group LDSD, N=20), or vice versa (group SDLD, N=20). The LDSD and SDLD does were also randomly assigned to one of two nutrition groups that received either 1.1 (H group, N=10) or 0.7 (L group, N=10) times their maintenance requirements. Live weight and body condition score were determined weekly and LH concentrations twice per week. To establish the pulsatility of secretion of LH, three periods of intensive sampling were undertaken. Melatonin was determined after a period of 45 short or long days. All photoperiod/nutrition groups showed large variations in LH concentrations according to photoperiod, with nutrition having a significant effect (Pnutrition group (at least Pnutrition groups, but differences between sampling periods were observed (Pgoats are sensitive to photoperiod, (2) that this environmental cue may control the timing of pituitary activity under natural conditions, and (3) suggest that nutrition plays an important role in the effect of photoperiod on LH secretion. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Changes in photoperiod alter Glut4 expression in skeletal muscle of C57BL/6J mice.

    Science.gov (United States)

    Tashiro, Ayako; Shibata, Satomi; Takai, Yusuke; Uchiwa, Tatsuhiro; Furuse, Mitsuhiro; Yasuo, Shinobu

    2017-03-25

    Seasonal changes in photoperiod influence body weight and metabolism in mice. Here, we examined the effect of changes in photoperiod on the expression of glucose transporter genes in the skeletal muscle and adipose tissue of C57BL/6J mice. Glut4 expression was lower in the gastrocnemius muscle of mice exposed to a short-duration day (SD) than those to a long-duration day (LD), with accompanying changes in GLUT4 protein levels. Although Glut4 expression in the mouse soleus muscle was higher under SD than under LD, GLUT4 protein levels remained unchanged. To confirm the functional significance of photoperiod-induced changes in Glut4 expression, we checked for variations in insulin sensitivity. Blood glucose levels after insulin injection remained high under SD, suggesting that the mice exposed to SD showed lower sensitivity to insulin than those exposed to LD. We also attempted to clarify the relationship between Glut4 expression and physical activity in the mice following changes in photoperiod. Locomotor activity, as detected via infrared beam sensor, was lower under SD than under LD. However, when we facilitated voluntary activity by using running wheels, the rotation of wheels was similar for both groups of mice. Although physical activity levels were enhanced due to running wheels, Glut4 expression in the gastrocnemius muscle remained unchanged. Thus, variations in photoperiod altered Glut4 expression in the mouse skeletal muscle, with subsequent changes in GLUT4 protein levels and insulin sensitivity; these effects might be independent of physical activity.

  8. Unitary Housing Regimes in Transition

    DEFF Research Database (Denmark)

    Bengtsson, Bo; Jensen, Lotte

    2013-01-01

    to the Danish and Swedish housing regimes are analysed and the responses and outcomes in terms of policy change and/or institutional continuity (path dependence) are compared. Overall, the more decentralized Danish housing regime seems to have resisted pressures for change and retrenchment better so far than...

  9. Regime shifts in resource management

    NARCIS (Netherlands)

    de Zeeuw, A.J.

    2014-01-01

    Resource management has to take account of the possibility of tipping points and regime shifts in ecological systems that provide the resources. This article focuses on the typical model of regime shifts in the ecological literature and analyzes optimal management and common-property issues when tra

  10. Examination Regimes and Student Achievement

    Science.gov (United States)

    Cosentino de Cohen, Clemencia

    2010-01-01

    Examination regimes at the end of secondary school vary greatly intra- and cross-nationally, and in recent years have undergone important reforms often geared towards increasing student achievement. This research presents a comparative analysis of the relationship between examination regimes and student achievement in the OECD. Using a micro…

  11. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of transnation

  12. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of

  13. Feeding tube insertion - gastrostomy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002937.htm Feeding tube insertion - gastrostomy To use the sharing features on this page, please enable JavaScript. A gastrostomy feeding tube insertion is the placement of a feeding ...

  14. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... 1- to 2-Year-Old Breastfeeding vs. Formula Feeding KidsHealth > For Parents > Breastfeeding vs. Formula Feeding Print ... a lactation specialist. previous continue All About Formula Feeding Commercially prepared infant formulas are a nutritious alternative ...

  15. Animal Feeding Operations

    Science.gov (United States)

    ... What's this? Submit Button Healthy Water Home Animal Feeding Operations Recommend on Facebook Tweet Share Compartir On ... Concentrated Animal Feeding Operations (CAFOs) What are Animal Feeding Operations (AFOs)? According to the United States Environmental ...

  16. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... A What's in this article? All About Breastfeeding Breastfeeding Challenges All About Formula Feeding Formula Feeding Challenges Making a Choice en español Lactancia materna versus lactancia artificial Choosing whether to breastfeed or formula feed their ...

  17. Phenology and growth adjustments of oil palm (Elaeis guineensis) to photoperiod and climate variability.

    Science.gov (United States)

    Legros, S; Mialet-Serra, I; Caliman, J-P; Siregar, F A; Clément-Vidal, A; Dingkuhn, M

    2009-11-01

    Oil palm flowering and fruit production show seasonal maxima whose causes are unknown. Drought periods confound these rhythms, making it difficult to analyse or predict dynamics of production. The present work aims to analyse phenological and growth responses of adult oil palms to seasonal and inter-annual climatic variability. Two oil palm genotypes planted in a replicated design at two sites in Indonesia underwent monthly observations during 22 months in 2006-2008. Measurements included growth of vegetative and reproductive organs, morphology and phenology. Drought was estimated from climatic water balance (rainfall - potential evapotranspiration) and simulated fraction of transpirable soil water. Production history of the same plants for 2001-2005 was used for inter-annual analyses. Drought was absent at the equatorial Kandista site (0 degrees 55'N) but the Batu Mulia site (3 degrees 12'S) had a dry season with variable severity. Vegetative growth and leaf appearance rate fluctuated with drought level. Yield of fruit, a function of the number of female inflorescences produced, was negatively correlated with photoperiod at Kandista. Dual annual maxima were observed supporting a recent theory of circadian control. The photoperiod-sensitive phases were estimated at 9 (or 9 + 12 x n) months before bunch maturity for a given phytomer. The main sensitive phase for drought effects was estimated at 29 months before bunch maturity, presumably associated with inflorescence sex determination. It is assumed that seasonal peaks of flowering in oil palm are controlled even near the equator by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with long time-lag. Resulting dynamics are complex, but if the present results are confirmed it will be possible to predict them with models.

  18. Matrix metalloproteinase inhibition influences aspects of photoperiod stimulated ovarian recrudescence in Siberian hamsters.

    Science.gov (United States)

    Shahed, Asha; Simmons, Jamie J; Featherstone, Sydney L; Young, Kelly A

    2015-05-15

    Blocking matrix metalloproteinase (MMP) activity in vivo with inhibitor GM6001 impedes photostimulated ovarian recrudescence in photoregressed Siberian hamsters. Since direct and indirect effects of MMPs influence a myriad of ovarian functions, we investigated the effect of in vivo MMP inhibition during recrudescence on ovarian mRNA expression of steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), Cyp19a1 aromatase, epidermal growth factor receptor (EGFR), amphiregulin (Areg), estrogen receptors (Esr1 and Esr2), tissue inhibitors of MMPs (TIMP-1,-2,-3), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor A (VEGFA), its receptor VEGFR-2, and angiopoietin-2 (Ang-2). Female Siberian hamsters were randomly assigned to one of four photoperiod groups: stimulatory long (LD) or inhibitory short (SD) photoperiods, or transferred from SD to LD for 2 weeks (post-transfer, PT). Half of the PT hamsters were injected (ip) daily with GM6001 (PTG). SD exposure reduced ovarian StAR, 3β-HSD, Cyp19a1, Esr1, Esr2, TIMPs 2-3, PCNA, VEGFR-2 and Ang-2 mRNA expression (p<0.05), and 2 weeks of photostimulation restored mRNA expression of 3β-HSD and PCNA and increased Areg and VEGFA mRNA expression in the PT group. GM6001 treatment during photostimulation (PTG) increased TIMP-1, -2 and -3 and PCNA mRNA, but inhibited Areg mRNA expression compared to PT. Neither photoperiod nor GM6001 altered EGFR expression. Results of this study suggest that in vivo inhibition of MMP activity by GM6001 may impede ovarian recrudescence, particularly follicular growth, in two ways: (1) directly by partially inhibiting the release of EGFR ligands like Areg, thereby potentially affecting EGFR activation and its downstream pathway, and (2) indirectly by its effect on TIMPs which themselves can affect proliferation, angiogenesis and follicular growth.

  19. Plasticity of muscle fibre number in seawater stages of Atlantic salmon in response to photoperiod manipulation.

    Science.gov (United States)

    Johnston, Ian A; Manthri, Sujatha; Smart, Alisdair; Campbell, Patrick; Nickell, David; Alderson, Richard

    2003-10-01

    Atlantic salmon (Salmo salar L.) were fed to satiety and reared from approximately 60 g to 5000 g at ambient seawater temperatures. The effect of photoperiod manipulation on muscle growth was investigated from the start of the first sea winter. Continuous light treatment in winter/spring (1 November to 18 June) improved growth performance in fish, resulting in a 30% increase in mean body mass relative to the ambient photoperiod fish by 12 August, but had no effect on sexual maturation. Significant increases in body mass in the continuous light groups were observed after 126 days (P<0.01). The number of fast muscle fibres per trunk cross-section was determined in a subset of the fish and was 28.5% higher in the continuous light (799 x 10(3)) than the natural day length (644 x 10(3)) groups after only 40 days, corresponding to the period of decreasing natural day length. Subsequent rates of fibre recruitment were similar between treatments. At the end of the fibre recruitment phase of growth (combined June and August samples), the maximum number of fast muscle fibres was 23% higher in fish from the cages receiving continuous light (881 x 10(3)+/-32 x 10(3); N=19) than in the ambient photoperiod cages (717 x 10(3)+/-15 x 10(3); N=20) (P<0.001). Continuous light treatment was associated with a shift in the distribution of fibre diameters, reflecting the altered patterns of fibre recruitment. However, the mean rate of fibre hypertrophy showed no consistent difference between treatments. There was a linear relationship between the myonuclear content of isolated single fibres and fibre diameter. On average, there were 27% more myonuclei in 150 microm-diameter fibres in the continuous light (3118 myonuclei cm(-1)) than the ambient photoperiod (2448 myonuclei cm(-1)) fish. After 40 days, continuous light treatment resulted in a transient increase in the density of myogenic progenitor cells, identified using a c-met antibody, to a level 70% above that of fish exposed to

  20. Acceleration of Microtuber Induction in Potato by Cytokinine and Photoperiod Adjustment

    Institute of Scientific and Technical Information of China (English)

    M F Alam; N Ahsan; M M Hossain; S Parvez; A M Swaraz; R Islam

    2003-01-01

    Protocol was developed for acceleration of microtuber induction in potato. It was observed that cytokinine (Kin), and both dark and light period had great influence on in vitro tuberization. Regarding concentration of Kin, 8 mg/l was found excellent for microtuber induction and formation under both dark and light conditions. Under continuous dark condition, higher percentage of explants (shoot) induced microtuber was observed than the short and long period of light conditions. For increasing the number and weight of microtuber product/explant, use of long photoperiod (16 h) is recommended.

  1. The Effect of Photoperiod on the Biomass and Quality Variables of Certain Origanum spp.

    OpenAIRE

    BAHTIYARCA BAGDAT, Reyhan; VYAS, Aditya; Craker, Lyle E.

    2016-01-01

    The biomass and essential oil yield of Origanum vulgare var. hirtum and O. syriacum were investigated under 10 h, 13 h and 16 h fluorescentlight with a temperature of 25°C (77 F)in the growth chamber. The effect of different photoperiods to the yield andquality variables of both species were recorded. The observations were takenfrom early flowering stage of the plants. The highest plant height was obtainedfrom O. syriacum with 13h photoperiodas 32.78 cm. The maximum number of shoot wasrecord...

  2. [Dynamic changes of rice (Oryza sativa L.) tiller angle under effects of photoperiod and effective accumulated temperature].

    Science.gov (United States)

    Ouyang, You-Nan; Li, Chun-Sheng; Zhang, Shan-Qing; Wang, Hui-Min; Zhu, Lian-Feng; Yu, Sheng-Miao; Jin, Qian-Yu; Zhang, Guo-Ping

    2009-05-01

    Using rice variety DI508 as test material, a field experiment of different seeding dates and a test with plant growth chamber were conducted to study the dynamic changes of rice tiller angle under effects of different photoperiod and effective accumulated temperature. Under field condition, the tiller angle of DI508 plants changed gradually into erect after 10-15 days of photoperiod becoming shorter (since the Summer Solstice on 21st June), irrespective of seeding dates (4th April, 5th May, and 4th June). Under controlled photoperiod, the tiller angle changed in the same way as in the field. Shorter lighting treatment (10 hours) advanced the tiller angle change, while longer lighting treatment (14 hours) delayed the change. Effective accumulated temperature had no effects on the tiller angle change of DI508.

  3. The effect of inductive photoperiod on flower formation and phytohormones level in a long day plant Hyoscyamus niger L.

    Directory of Open Access Journals (Sweden)

    J. Kopcewicz

    2015-05-01

    Full Text Available The anatomical and hormonal investigations on a long day plant Hyoscyamus niger L. during the time of the generative photoinduction have been conducted. The plants were grown during 75 days on a short photoperiod and then they were transferred to long day conditions. The earliest anatomical symptoms of flower initiation were noticed after four long photoperiods. The inductive photoperiod causes also a general increase in the amounts of phytohormones. During the flower evocation the intensive accumulation of cytokinins and gibberellins in leaves takes place. The post-inductive period, in which the development of flower elements happens, is characterized by changing amount of phytohormones. The content of hormonal substances is subjected to the rhytmical changes related to the periods of light and darknees in the twenty four hours' cycle.

  4. Photoperiod regulates growth of male accessory glands through juvenile hormone signaling in the linden bug, Pyrrhocoris apterus.

    Science.gov (United States)

    Urbanová, Veronika; Bazalová, Olga; Vaněčková, Hanka; Dolezel, David

    2016-03-01

    Adult reproductive diapause is characterized by lower behavioral activity, ceased reproduction and absence of juvenile hormone (JH). The role of JH receptor Methoprene-tolerant (Met) in female reproduction is well established; however, its function in male reproductive development and behavior is unclear. In the bean bug, Riptortus pedestris, circadian genes are essential for mediating photoperiodically-dependent growth of the male accessory glands (MAGs). The present study explores the role of circadian genes and JH receptor in male diapause in the linden bug, Pyrrhocoris apterus. These data indicate that circadian factors Clock, Cycle and Cry2 are responsible for photoperiod measurement, whereas Met and its partner protein Taiman participate in JH reception. Surprisingly, knockdown of the JH receptor neither lowered locomotor activity nor reduced mating behavior of males. These data suggest existence of a parallel, JH-independent or JH-upstream photoperiodic regulation of reproductive behavior.

  5. Review: Regulatory mechanisms of gonadotropin-inhibitory hormone (GnIH synthesis and release in photoperiodic animals

    Directory of Open Access Journals (Sweden)

    Kazuyoshi eTsutsui

    2013-04-01

    Full Text Available Gonadotropin-inhibitory hormone (GnIH is a novel hypothalamic neuropeptide that was discovered in quail as an inhibitory factor for gonadotropin release. GnIH inhibits gonadotropin synthesis and release in birds through actions on gonadotropin-releasing hormone (GnRH neurons and gonadotropes, mediated via the GnIH receptor (GnIH-R, GPR147. Subsequently, GnIH was identified in mammals and other vertebrates. As in birds, mammalian GnIH inhibits gonadotropin secretion, indicating a conserved role for this neuropeptide in the control of the hypothalamic-pituitary-gonadal (HPG axis across species. Identification of the regulatory mechanisms governing GnIH expression and release is important in understanding the physiological role of the GnIH system. A nocturnal hormone, melatonin, appears to act directly on GnIH neurons through its receptor to induce expression and release of GnIH in quail, a photoperiodic bird. Recently, a similar, but opposite, action of melatonin on the inhibition of expression of mammalian GnIH was shown in hamsters and sheep, photoperiodic mammals. These results in photoperiodic animals demonstrate that GnIH expression is photoperiodically modulated via a melatonin-dependent process. Recent findings indicate that GnIH may be a mediator of stress-induced reproductive disruption in birds and mammals, pointing to a broad role for this neuropeptide in assessing physiological state and modifying reproductive effort accordingly. This paper summarizes the advances made in our knowledge regarding the regulation of GnIH synthesis and release in photoperiodic birds and mammals. This paper also discusses the neuroendocrine integration of environmental signals, such as photoperiods and stress, and internal signals, such as GnIH, melatonin and glucocorticoids, to control avian and mammalian reproduction.

  6. Acute downregulation of Type II and Type III iodothyronine deiodinases by photoperiod in peripubertal male and female Siberian hamsters.

    Science.gov (United States)

    Kampf-Lassin, August; Prendergast, Brian J

    2013-11-01

    Availability of the thyroid hormone triiodothyronine (T3) in the mediobasal hypothalamus plays a central role in seasonal reproductive responses to photoperiod. Across many vertebrates, Type 2 iodothyronine deiodinase (DIO2) is elevated under reproductively stimulatory long days (LD) and synthesizes the conversion of thyroxine to T3; Type 3 iodothyronine deiodinase (DIO3) reduces T3 production and signaling, and is upregulated under reproductively-inhibitory short days (SD). In Siberian hamsters, regulation of hypothalamic T3 is dominated by dio3 expression, whereas dio2 expression is less-consistently affected by photoperiod. In adult hamsters, changes in deiodinase mRNA expression typically require several weeks to manifest, but it is not known whether or how quickly these mechanisms are engaged during the rapid responses to photoperiod observed in young, peri-pubertal hamsters. This experiment tested the hypotheses that (1) deiodinase responses to photoperiod are accelerated in juvenile hamsters and (2) photoperiodic downregulation of deiodinase expression occurs more rapidly than upregulation. Hypothalamic dio2 and dio3 mRNA expression was quantified in male and female Siberian hamsters that were weaned on postnatal day 18 (PND 18) into SD or remained in their natal LD, and on PND 31 were exposed to a single long or short day. In SD males and females, a single long day inhibited dio3 mRNA expression, but did not increase dio2 mRNA. In LD males, a single short day rapidly inhibited dio2 mRNA expression, but did not stimulate expression of dio3 mRNA. Downregulation of dio2 and dio3 mRNAs precedes gonadotrophin responses to day length. Rapid photoperiodic inhibition of deiodinase mRNAs may initiate changes in thyroid hormone signaling in advance of longer-term, melatonin-dependent, responses.

  7. Functional and Evolutionary Characterization of the CONSTANS Gene Family in Short-Day Photoperiodic Flowering in Soybean

    OpenAIRE

    2014-01-01

    CONSTANS (CO) plays a central role in photoperiodic flowering control of plants. However, much remains unknown about the function of the CO gene family in soybean and the molecular mechanisms underlying short-day photoperiodic flowering of soybean. We identified 26 CO homologs (GmCOLs) in the soybean genome, many of them previously unreported. Phylogenic analysis classified GmCOLs into three clades conserved among flowering plants. Two homeologous pairs in Clade I, GmCOL1a/GmCOL1b and GmCOL2a...

  8. Photoperiodic changes in opiate binding and their functional implications in golden hamsters.

    Science.gov (United States)

    Tubbiola, M L; Nock, B; Bittman, E L

    1989-11-27

    Daylength modulates gonadotropin secretion, gonadal steroid hormone feedback, sexual behavior and body weight in male golden hamsters. Endogenous opiates regulate each of these phenomena, and the ability of opiate receptor blockade to elevate serum LH secretion is photoperiod-dependent. We used in vitro autoradiography to localize and quantify effects of daylength in golden hamsters. Hamsters were exposed to stimulatory (14 h light: 10 h dark) or inhibitory (10 h light: 14 h dark) photoperiods for 10 weeks before specific [3H]naloxone binding was assessed. Short days significantly decreased binding in medial amygdala and the intercalated amygdaloid nucleus. This effect was reversed by superior cervical ganglionectomy. No significant effects of daylength were observed in other amygdaloid, hypothalamic or preoptic areas. Lesions of the medial amygdala decreased copulatory behavior, short day-induced weight loss, and anogenital chemoinvestigation but did not affect gonadal regression or other forms of chemoinvestigation. These lesions facilitated testosterone's negative feedback on luteinizing hormone in long days but did not interfere with the potentiation of negative feedback by short days.

  9. The Effect of Different Photoperiods in Circadian Rhythms of Per3 Knockout Mice

    Directory of Open Access Journals (Sweden)

    D. S. Pereira

    2014-01-01

    Full Text Available The aim of this study was to analyse the circadian behavioural responses of mice carrying a functional knockout of the Per3 gene (Per3−/− to different light : dark (L : D cycles. Male adult wild-type (WT and Per3−/− mice were kept under 12-hour light : 12-hour dark conditions (12L : 12D and then transferred to either a short or long photoperiod and subsequently released into total darkness. All mice were exposed to both conditions, and behavioural activity data were acquired through running wheel activity and analysed for circadian characteristics during these conditions. We observed that, during the transition from 12L : 12D to 16L : 8D, Per3−/− mice take approximately one additional day to synchronise to the new L : D cycle compared to WT mice. Under these long photoperiod conditions, Per3−/− mice were more active in the light phase. Our results suggest that Per3−/− mice are less sensitive to light. The data presented here provides further evidence that Per3 is involved in the suppression of behavioural activity in direct response to light.

  10. Timing of photoperiodic competency causes phenological mismatch in balsam poplar (Populus balsamifera L.).

    Science.gov (United States)

    Soolanayakanahally, Raju Y; Guy, Robert D; Silim, Salim N; Song, Minghua

    2013-01-01

    Plant phenology is expected to be sensitive to climate warming. In boreal trees, spring flush is primarily temperature driven, whereas height growth cessation and autumn leaf senescence are predominantly controlled by photoperiod. Cuttings of 525 genotypes from the full range of balsam poplar were planted into two common gardens (Vancouver and Indian Head, Canada) at similar latitudes, but with differing winter temperatures and growing seasons. There was clinal variation in spring and, particularly, summer and fall phenology. Bud flush and, despite milder climate, bud set and leaf drop were earlier at Vancouver than at Indian Head by 44, 28 and 7 d, respectively. Although newly flushed growth is insensitive to photoperiod, many genotypes at both sites became competent before the summer solstice. At Vancouver, high-latitude genotypes set dormant terminal buds in mid-spring. Most other genotypes grew until midsummer or set bud temporarily and then experienced a second flush. In both gardens and in a growth chamber experiment, earlier bud set was associated with reduced height growth and higher root/shoot ratios. Shoots attained competency ~5 weeks after flushing, which would normally prevent dormancy induction before the solstice, but may be insufficient if spring advances by more than a few weeks.

  11. Spatio-temporal variation of the diterpene steviol in Stevia rebaudiana grown under different photoperiods.

    Science.gov (United States)

    Ceunen, Stijn; Geuns, Jan M C

    2013-05-01

    As part of an ongoing study on the effects of photoperiodism on the metabolism of steviol glycosides (SVglys) in Stevia rebaudiana, the spatio-temporal variations of free steviol (SV) have now been evaluated. For its quantitation, an internal standard method was used, based upon a specific fluorometric detection of SV as its methoxycoumarinyl derivative. The level of free SV in leaves did not exceed 30 μg/g dry wt and was at least 1000-fold smaller than that of its glycosidic conjugates. In other organs, free SV was mainly measured in stem tissue and apices, with relatively large amounts measured in the latter. Similarly to SVglys, the content of free SV was influenced by photoperiod and genotype. In plants grown under long-days (LD) of 16 h, more spatial variations were seen compared to those under short-days (SD) of 8h. In the former, upper leaves contained almost four times more free SV compared to lower ones near the end of vegetative growth. In addition, the correlation between SV and its glycosidic conjugates was more linear under SD. Despite the variability of SV levels, a decrease was noted in all conditions after flower opening, which can be related a decreased transcription of the biosynthetic genes involved.

  12. Non-photoperiodic regulation of reproductive physiology in the flexibly breeding pine siskin (Spinus pinus).

    Science.gov (United States)

    Watts, Heather E; Hahn, Thomas P

    2012-09-01

    In order to time reproduction to coincide with favorable conditions, animals use environmental cues to up- and down-regulate the reproductive axis appropriately. Although photoperiodic cues are one of the best studied of such environmental cues, animals also attend to others such as temperature, food availability, rainfall and social cues. Such non-photic cues are expected to be particularly important for tropical species and temperate-zone species that exhibit flexible or opportunistic breeding schedules. In this study, we investigate the use of non-photic cues, specifically food availability and social cues, to time the initiation of reproductive development in the pine siskin (Spinus pinus), a temperate-zone songbird with a flexible breeding schedule. Following winter solstice, males were housed on a 12L:12D photoperiod with either access to a preferred food, a potential mate (social cue), or both. Control birds received only maintenance diet and no mate. Access to a preferred food had a significant positive effect on testis size and circulating luteinizing hormone (LH). However, we found no effect of social treatment on reproductive development. The effect of the food treatment on reproductive development did not appear to result from effects on body mass or fat, as neither measure differed across treatments. The food treatment influenced not only reproductive physiology, but also reproductive behavior in this species, as access to seeds had a positive effect on affiliation of pairs. This study demonstrates that food is a potent stimulus for the initiation of reproductive development in pine siskins.

  13. Endogenous gibberellins and stem growth as related to photoperiod in Silene armeria L

    Energy Technology Data Exchange (ETDEWEB)

    Talon, M.; Zeevaart, J.A.D. (Michigan State Univ., East Lansing (USA))

    1989-04-01

    The early 13-hydroxylation gibberellin (GA) pathway operates in the long-day plant Silene armeria grown under both long-day (LD) and short-day (SD) conditions. Thus, induction of stem growth must be related to quantitative changes in GA pattern. Using GC-SIM-MS and GAs labeled with stable isotopes as internal standards, the levels of GA{sub 53}, GA{sub 19}, GA{sub 20}, and GA{sub 1} were measured in shoots and various organs of plants grown under different photoperiods. Exposure to 8 LD decreased the levels of GA{sub 53} and GA{sub 19}, and increased the levels of GA{sub 20} and particularly of GA{sub 1}; the latter GA accumulated to very high levels in expanding leaves and tips. When plants were exposed to LD, followed by SD, GA levels decreased, and the relative increases in stem length were correlated with the level of GA{sub 1} at the time the plants were returned to SD. These observations suggest that GA{sub 53}-oxidase, and probable also GA{sub 19}-oxidase, are under photoperiodic control. Furthermore, GA{sub 1} appears to be active per se in Silene in causing stem growth, since its level was always correlated with the degree of stem elongation.

  14. Phenolic Profile of Dark-Grown and Photoperiod-Exposed Hypericum perforatum L. Hairy Root Cultures

    Directory of Open Access Journals (Sweden)

    Oliver Tusevski

    2013-01-01

    Full Text Available Hypericum perforatum L. is a medicinal plant considered as an important natural source of secondary metabolites with a wide range of pharmacological attributes. Hairy roots (HR were induced from root segments of in vitro grown seedlings from H. perforatum after cocultivation with Agrobacterium rhizogenes A4. Investigations have been made to study the production of phenolic compounds in dark-grown (HR1 and photoperiod-exposed (HR2 cultures. The chromatographic analysis of phenolic acids, flavonols, flavan-3-ols, and xanthones revealed marked differences between HR1 and HR2 cultures. The production of quinic acid, kaempferol, and seven identified xanthones was increased in HR2. Moreover, HR2 showed a capability for de novo biosynthesis of two phenolic acids (3-p-coumaroylquinic acid and 3-feruloylquinic acid, three flavonol glycosides (kaempferol hexoside, hyperoside, and quercetin acetylglycoside, and five xanthones (tetrahydroxy-one-methoxyxanthone, 1,3,5-trihydroxy-6-methoxyxanthone, 1,3,5,6-tetrahydroxy-2-prenylxanthone, paxanthone, and banaxanthone E. On the other side, HR1 cultures were better producers of flavan-3-ols (catechin, epicatechin, and proanthocyanidin dimers than HR2. This is the first comparative study on phenolic profile of H. perforatum HR cultures grown under dark and photoperiod conditions.

  15. Reproductive responses of male Brandt's voles ( Lasiopodomys brandtii) to 6-methoxybenzoxazolinone (6-MBOA) under short photoperiod

    Science.gov (United States)

    Dai, Xin; Jiang, Lian Yu; Han, Mei; Ye, Man Hong; Wang, Ai Qin; Wei, Wan Hong; Yang, Sheng Mei

    2016-04-01

    The plant secondary metabolite 6-methoxybenzoxazolinone (6-MBOA) can stimulate and enhance animal reproduction. This compound has been successfully detected in Leymus chinensis, which is the main diet of Brandt's voles. The aim of this study was to investigate the effect of different 6-MBOA doses on the reproductive physiology of male Brandt's voles under a short photoperiod. The results showed that 6-MBOA administration increased relative testis weight, regardless of the dose, but it had little effect on the body mass. Low and middle doses of 6-MBOA increased the concentrations of luteinizing hormone and testosterone in the serum and the mRNA levels of StAR and CYP11a1 in the testes. However, 6-MBOA did not cause any significant increase in the mRNA levels of KiSS-1, GPR54, and GnRH compared to those in the control group. The mRNA level of KiSS-1 in the arcuate nucleus (ARC) was higher than that in the anteroventral periventricular nucleus (AVPV). Collectively, our results demonstrated that the number of KiSS-1-expressing neurons located in the ARC was the highest, and that 6-MBOA, which might modulate the reproductive activity along the hypothalamic-pituitary-gonadal axis, had a dose-dependent stimulatory effect on the reproductive activity of Brandt's voles under a short photoperiod. Our study provided insights into the mechanism of 6-MBOA action and the factors influencing the onset of reproduction in Brandt's voles.

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

    Science.gov (United States)

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

    2010-10-01

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

  17. [Ultrastructure of the ovarioles of Tropidacris collaris (Stoll) (Orthoptera: Romaleidae) submitted to three photoperiods].

    Science.gov (United States)

    Santos, Fabiana D; Veiga, Antônio F S L; Santos, Fabio A B; Torres, Jorge B; Teixeira, Alvaro A C; Wanderley-Teixeira, Valéria

    2007-01-01

    The research evaluated the ultrastructure of the ovarioles of Tropidacris collaris (Stoll), submitted to photoperiods 10L:14D, 12L:12D and 14L:10D. Sixty nymphs (30 males and 30 females) in the last stage of development were paired in ten couples in each treatment. Thirty days after adult emergence, the females were immobilized with ethylic ether and dissected under stereomicroscope. The ovarioles were transferred to Karnovsky fixative (2.5% glutaraldehyde, 4% paraformaldehyde and 0.1 M sodium cacodylate buffer) and analyzed in transmission and scanning electron microscopes. The different photoperiods had no effect on the ovarioles' ultrastructure. Each ovariole is covered by a thick sheath constituted by a homogeneous and filamentous material. In the terminal filament, there are cells with large nuclei, some with scarce cytoplasm and projections cytoplasmatic, besides filamentous structures assuming characteristic of conjunctive tissue. In the germarium, the germ cells are big with large nuclei, scarce cytoplasm and plasma membrane containing interdigitations. The follicular cells are small with a small nucleus, yet presenting cytoplasmatic projections. In the vitellarium the follicular cells suffer modifications in their morphology varying from cubic to flat.

  18. Molecular dissection of the roles of phytochrome in photoperiodic flowering in rice.

    Science.gov (United States)

    Osugi, Asami; Itoh, Hironori; Ikeda-Kawakatsu, Kyoko; Takano, Makoto; Izawa, Takeshi

    2011-11-01

    Phytochromes mediate the photoperiodic control of flowering in rice (Oryza sativa), a short-day plant. Recent molecular genetics studies have revealed a genetic network that enables the critical daylength response of florigen gene expression. Analyses using a rice phytochrome chromophore-deficient mutant, photoperiod sensitivity5, have so far revealed that within this network, phytochromes are required for expression of Grain number, plant height and heading date7 (Ghd7), a floral repressor gene in rice. There are three phytochrome genes in rice, but the roles of each phytochrome family member in daylength response have not previously been defined. Here, we revealed multiple action points for each phytochrome in the critical daylength response of florigen expression by using single and double phytochrome mutant lines of rice. Our results show that either phyA alone or a genetic combination of phyB and phyC can induce Ghd7 mRNA, whereas phyB alone causes some reduction in levels of Ghd7 mRNA. Moreover, phyB and phyA can affect Ghd7 activity and Early heading date1 (a floral inducer) activity in the network, respectively. Therefore, each phytochrome gene of rice has distinct roles, and all of the phytochrome actions coordinately control the critical daylength response of florigen expression in rice.

  19. The Choice of Monetary Regime

    DEFF Research Database (Denmark)

    Østrup, Finn

    , a comparisonbetween monetary regimes suggests that welfare is highest under nominalincome targeting where the nominal income target is determined to bring aboutprice stability.Keywords: Monetary regimes; fiscal policy; monetary non-neutrality.JEL classicification: E42, E61, E62.......The article examines how government spending is determined in a closedeconomy where the nominal wage is pre-set through contracts and the wage settershave perfect foresight regarding subsequent policy decisions. The monetaryregime affects government spending because: (i) with a pre-set nominal wage......, agiven change in government spending has different effects on employment andinflation under different monetary regimes, and (ii) the authorities' inclinationto expand government spending is affected by the inflation rate which dependson the monetary regime. If the costs related to inflation are high...

  20. THE ETHIOPIAN ENVIRONMENTAL REGIME VERSUS ...

    African Journals Online (AJOL)

    Haramaya Law Review ... ozone layer and climate change regimes, among others, to succeed. Id. ... international act dealing with general aspects of air pollution. ..... environmental and developmental decisions that affect their interests or the.

  1. Performance of photoperiod and light intensity on biogas upgrade and biogas effluent nutrient reduction by the microalgae Chlorella sp.

    Science.gov (United States)

    Yan, Cheng; Zheng, Zheng

    2013-07-01

    Biogas is an environment-friendly fuel but that must be upgraded before being utilized. The method about removing CO2 from biogas by microalgal culturing using biogas effluent as nutrient medium in this study could effectively upgrade biogas and simultaneously reduce the biogas effluent nutrient. Results showed that the optimum parameters for microalgal growth and biogas effluent nutrient reduction was moderate light intensity with middle photoperiod. While low light intensity with long photoperiod and moderate light intensity with middle photoperiod obtained the best biogas CO2 removal and biogas upgrade effects. Therefore, the optimal parameters were moderate light intensity 350 μmol m(-2)s(-1) with middle photoperiod 14 h light:10h dark. Under this condition, the microalgal dry weight, CH4 concentration, reduction efficiency of chemical oxygen demand, total nitrogen, and total phosphorus was 615.84 ± 33.07 mg L(-1), 92.16 ± 2.83% (v/v), 88.74 ± 3.45%, 83.94 ± 3.51%, and 80.43 ± 4.17%, respectively.

  2. Sand rats see the light: short photoperiod induces a depression-like response in a diurnal rodent.

    Science.gov (United States)

    Einat, Haim; Kronfeld-Schor, Noga; Eilam, David

    2006-10-02

    The present study examined the effect of simulated change in day length on the behavior of a diurnal rodent, the fat sand rat (a species of gerbil). Animals were housed under a short photoperiod (5/19 light/dark cycle) for 3 weeks and compared with controls living under a 12/12 light/dark cycle. All sand rats then underwent the forced swim test for depression-like behavior, and the open-field test for overall activity. Sand rats exposed to the short photoperiod displayed a significantly earlier sinking in the swim test, but there was no difference between their open-field activity compared with controls. Taking these responses as indicative of depression-like behavior, we suggest that a short photoperiod may induce affective-like changes, and that the sand rat may thus offer an appropriate animal model to explore the effect of photoperiod on normal, and perhaps also abnormal, seasonal mood changes (e.g., SAD), which in humans is a prevalent disorder, with winter depression episodes and spring/summer remissions.

  3. Effect of photoperiod on body weight gain, and daily energy intake and energy expenditure in Japanese quail (Coturnix c. Japonica)

    NARCIS (Netherlands)

    Boon, P; Visser, GH; Daan, S

    2000-01-01

    Effect of photoperiod and food duration on body weight gain, energy intake, energy expenditure, and sexual development were investigated in two strains of Japanese quail (Coturnix c. japonica), bred for meat (broilers) or egg production (layers), from 7 to 71 days of age. In a first experiment

  4. Differential expression of circadian clock genes in two strains of beetles reveals candidates related to photoperiodic induction of summer diapause.

    Science.gov (United States)

    Zhu, Li; Liu, Wen; Tan, Qian-Qian; Lei, Chao-Liang; Wang, Xiao-Ping

    2017-03-01

    Diapause (also known as dormancy) is a state of arrested development induced by photoperiod or temperature that allows insects to survive adverse environmental conditions. By regulating diapause induction, the circadian clock is involved in short-day-induced winter diapause but whether this is also the case in long-day (LD)-induced summer diapause remains unknown. The cabbage beetle Colaphellus bowringi could enter summer diapause under LD conditions. However, a non-photoperiodic-diapause (NPD) strain of this species, which was developed in our laboratory by artificial selection, could not enter diapause under LD photoperiod. Therefore, we identified circadian clock genes in this species and measured differences in their expression between a high diapause (HD) strain and the NPD strain to investigate the potential relationship between circadian clock genes and summer diapause induction in C. bowringi. We successfully cloned eight circadian clock genes and obtained intact ORFs of four; cryptochrome2, double-time, shaggy and vrille. Phylogenetic trees and sequence alignment analyses indicated that these circadian clock genes were conserved across insect taxa. The quantitative real-time PCR indicated that clock, cycle, period, timeless, cryptochrome2, and vrille were differentially expressed between HD and NPD strains reared under LD photoperiod during the diapause induction phase. These findings suggest the potential relationship between circadian clock genes and LD-regulated summer diapause induction in C. bowringi.

  5. Effect of temperature and photoperiod on the development, reproduction, and predation of the predatory ladybird Cheilomenes sexmaculata (Coleoptera: Coccinellidae).

    Science.gov (United States)

    Wang, Su; Tan, Xiao-Ling; Guo, Xiao-Jun; Zhang, Fan

    2013-12-01

    The polyphagous predatory ladybird Cheilomenes. sexmaculata (F.) (Coleoptera: Coccinellidae) is distributed throughout southern China and has been investigated as a potential biological control agent against herbivorous insects in various agroecosystems. In the current study, we evaluated the preimaginal development, eclosion rate, reproduction, fertility, adult longevity, and prey consumption of C. sexmaculata under five temperature and five photoperiod regimens. The results showed that preadult developmental duration decreased significantly with increasing temperature and amount of daylight. Adult eclosion rate was highest at 35 degrees C and under conditions of complete darkness. Higher temperatures shortened the duration of copulation and preoviposition, prolonged the duration of oviposition, and increased the level of fecundity. Hatchability was highest at 30 degrees C. By contrast, the shortest copulation and oviposition duration and lowest level of fecundity and hatchability occurred with a completely dark photoperiod. Temperature and the gender of C. sexmaculata influenced adult longevity. In addition, there was a significant interaction effect of photoperiod and gender on adult longevity. Furthermore, prey consumption by fourth instar larvae and adult females both increased with increasing temperature and photoperiod. Our results reveal the high thermal and light sensitivities of C. sexmaculata, which highlight the importance of environment regulation in the mass rearing of this natural enemy for application as a biological control in agroecosystems in China.

  6. Photoperiod mediated changes in olfactory bulb neurogenesis and olfactory behavior in male white-footed mice (Peromyscus leucopus.

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    James C Walton

    Full Text Available Brain plasticity, in relation to new adult mammalian neurons generated in the subgranular zone of the hippocampus, has been well described. However, the functional outcome of new adult olfactory neurons born in the subventricular zone of the lateral ventricles is not clearly defined, as manipulating neurogenesis through various methods has given inconsistent and conflicting results in lab mice. Several small rodent species, including Peromyscus leucopus, display seasonal (photoperiodic brain plasticity in brain volume, hippocampal function, and hippocampus-dependent behaviors; plasticity in the olfactory system of photoperiodic rodents remains largely uninvestigated. We exposed adult male P. leucopus to long day lengths (LD and short day lengths (SD for 10 to 15 weeks and then examined olfactory bulb cell proliferation and survival using the thymidine analog BrdU, olfactory bulb granule cell morphology using Golgi-Cox staining, and behavioral investigation of same-sex conspecific urine. SD mice did not differ from LD counterparts in granular cell morphology of the dendrites or in dendritic spine density. Although there were no differences due to photoperiod in habituation to water odor, SD mice rapidly habituated to male urine, whereas LD mice did not. In addition, short day induced changes in olfactory behavior were associated with increased neurogenesis in the caudal plexiform and granule cell layers of the olfactory bulb, an area known to preferentially respond to water-soluble odorants. Taken together, these data demonstrate that photoperiod, without altering olfactory bulb neuronal morphology, alters olfactory bulb neurogenesis and olfactory behavior in Peromyscus leucopus.

  7. Orchestration of gene expression across the seasons: Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster.

    Science.gov (United States)

    Petri, Ines; Diedrich, Victoria; Wilson, Dana; Fernández-Calleja, José; Herwig, Annika; Steinlechner, Stephan; Barrett, Perry

    2016-07-11

    In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July.

  8. Photoperiodic regulation of histamine H3 receptor and VGF messenger ribonucleic acid in the arcuate nucleus of the Siberian hamster.

    Science.gov (United States)

    Barrett, Perry; Ross, Alexander W; Balik, Ales; Littlewood, Pauline A; Mercer, Julian G; Moar, Kim M; Sallmen, Tina; Kaslin, Jan; Panula, Pertti; Schuhler, Sandrine; Ebling, Francis J; Ubeaud, Caroline; Morgan, Peter J

    2005-04-01

    To survive winter the Siberian hamster has evolved profound physiological and behavioral adaptations, including a moult to winter pelage, regression of the reproductive axis, onset of daily torpor and increased capacity for thermogenesis. However, one of the most striking adaptations is the catabolism of intraabdominal and sc fat reserves contributing to the loss of up to 40% of body weight. These physiological and behavioral adaptations are photoperiodically driven, yet neither the site(s) in the brain nor the molecular mechanism(s) involved in the regulation of these profound adaptations is known. Here we report a dynamic regulation of gene expression in a dorsal region of the medial posterior area of the arcuate nucleus (dmpARC) of the Siberian and Syrian hamster brain in response to altered photoperiod. We show mRNA for the histamine H3 receptor is down-regulated and VGF is up-regulated in the dmpARC in hamsters switched from long- to short-day photoperiod. These data provide further evidence to support the view that the dmpARC is a major site to relay photoperiodic changes and as a site for the long-term regulation of seasonal physiology and behavior.

  9. Photoperiod and acute energy deficits interact on components of the thyroid hormone system in hypothalamic tanycytes of the Siberian hamster

    NARCIS (Netherlands)

    A. Herwig; D. Wilson; T.J. Logie; A. Boelen; P.J. Morgan; J.G. Mercer; P. Barrett

    2009-01-01

    Herwig A, Wilson D, Logie TJ, Boelen A, Morgan PJ, Mercer JG, Barrett P. Photoperiod and acute energy deficits interact on components of the thyroid hormone system in hypothalamic tanycytes of the Siberian hamster. Am J Physiol Regul Integr Comp Physiol 296: R1307-R1315, 2009. First published March

  10. Rescue of photoperiod/freeze-sensitive and low seed producing accessions of Lablab purpureus using hydroponic cloning and aeroponics.

    Science.gov (United States)

    Hyacinth bean, Lablab purpureus is a legume used as a vegetable and the USDA, ARS, PGRCU conserves 137 hyacinth bean accessions from countries worldwide. Many accessions in this collection are photoperiod and freeze-sensitive due to their flower and seed production during November through March in t...

  11. Seed rescue from photoperiod sensitive American Joint Vetch (Aeschynomene americana L.) accessions using hydroponic cloning and aeroponics

    Science.gov (United States)

    American joint vetch, Aeschynomene Americana L. is a self-pollinated tropical pasture legume and the USDA, ARS, PGRCU curates 137 accessions from the United States, S. America, Mexico, Central America, and Zambia. Many accessions in this collection are photoperiod sensitive due to their typical flow...

  12. Erwin Bünning and Tony Lees, two giants of chronobiology, and the problem of time measurement in insect photoperiodism.

    Science.gov (United States)

    Saunders, D S

    2005-06-01

    This paper examines the views of Erwin Bünning and Tony Lees on the mechanism of photoperiodic time measurement, the former advocating a circadian basis for the phenomenon and the latter a non-circadian hourglass-like timer. This difference in opinion led to a protracted split among workers on photoperiodism, some supporting an oscillatory clock and others an "hourglass", and gave rise to the often stated opinion that the two forms of time measurement were mutually exclusive. This paper, however, suggests that both oscillatory and hourglass-like properties are to be seen in insect photoperiodism. Furthermore, the differences between the two apparently conflicting models may be resolved if, following Bünning, "hourglasses" are regarded as damping circadian oscillators, with the more self-sustained (clearly oscillatory) and more highly damped (hourglass-like) responses being parts of a continuous series. Since circadian rhythmicity is an all-pervading and fundamental aspect of insect biology, currently opening up to genetic and molecular analysis, recognition of the basic similarity of a wide range of insect photoperiodic timers may help to unravel the biochemical nature of the mechanism(s) involved.

  13. Photoperiodic regulation of glycogen metabolism, glycolysis, and glutamine synthesis in tanycytes of the Siberian hamster suggests novel roles of tanycytes in hypothalamic function.

    Science.gov (United States)

    Nilaweera, Kanishka; Herwig, Annika; Bolborea, Matei; Campbell, Gill; Mayer, Claus D; Morgan, Peter J; Ebling, Francis J P; Barrett, Perry

    2011-11-01

    The objective of this study is to investigate the impact of photoperiod on the temporal and spatial expression of genes involved in glucose metabolism in the brain of the seasonal mammal Phodopus sungorus (Siberian hamster). In situ hybridization was performed on brain sections obtained from male hamsters held in long photoperiod (high body weight and developed testes) or short photoperiod (reduced body weight with testicular regression). This analysis revealed upregulation in expression of genes involved in glycogen and glucose metabolism in short photoperiod and localized to the tanycyte layer of the third ventricle. On the basis of these data and a previously identified photoperiod-dependent increase in activity of neighboring hypothalamic neurons, we hypothesized that the observed expression changes may reflect alteration in either metabolic fuel or precursor neurotransmitter supply to surrounding neurons. Gene expression analysis was performed for genes involved in lactate and glutamate transport. This analysis showed that the gene for the lactate transporter MCT2 and glutamate transporter GLAST was decreased in the tanycyte layer in short photoperiod. Expression of mRNA for glutamine synthetase, the final enzyme in the synthesis of the neuronal neurotransmitter precursor, glutamine, was also decreased in short photoperiod. These data suggest a role for tanycytes in modulating glutamate concentrations and neurotransmitter supply in the hypothalamic environment.

  14. The comparison between circadian oscillators in mouse liver and pituitary gland reveals different integration of feeding and light schedules.

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    Isabelle M Bur

    Full Text Available The mammalian circadian system is composed of multiple peripheral clocks that are synchronized by a central pacemaker in the suprachiasmatic nuclei of the hypothalamus. This system keeps track of the external world rhythms through entrainment by various time cues, such as the light-dark cycle and the feeding schedule. Alterations of photoperiod and meal time modulate the phase coupling between central and peripheral oscillators. In this study, we used real-time quantitative PCR to assess circadian clock gene expression in the liver and pituitary gland from mice raised under various photoperiods, or under a temporal restricted feeding protocol. Our results revealed unexpected differences between both organs. Whereas the liver oscillator always tracked meal time, the pituitary circadian clockwork showed an intermediate response, in between entrainment by the light regimen and the feeding-fasting rhythm. The same composite response was also observed in the pituitary gland from adrenalectomized mice under daytime restricted feeding, suggesting that circulating glucocorticoids do not inhibit full entrainment of the pituitary clockwork by meal time. Altogether our results reveal further aspects in the complexity of phase entrainment in the circadian system, and suggest that the pituitary may host oscillators able to integrate multiple time cues.

  15. Photoperiodic Modulation of Circadian Clock and Reproductive Axis Gene Expression in the Pre-Pubertal European Sea Bass Brain.

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    Rute S T Martins

    Full Text Available The acquisition of reproductive competence requires the activation of the brain-pituitary-gonad (BPG axis, which in most vertebrates, including fishes, is initiated by changes in photoperiod. In the European sea bass long-term exposure to continuous light (LL alters the rhythm of reproductive hormones, delays spermatogenesis and reduces the incidence of precocious males. In contrast, an early shift from long to short photoperiod (AP accelerates spermatogenesis. However, how photoperiod affects key genes in the brain to trigger the onset of puberty is still largely unknown. Here, we investigated if the integration of the light stimulus by clock proteins is sufficient to activate key genes that trigger the BPG axis in the European sea bass. We found that the clock genes clock, npas2, bmal1 and the BPG genes gnrh, kiss and kissr share conserved transcription factor frameworks in their promoters, suggesting co-regulation. Other gene promoters of the BGP axis were also predicted to be co-regulated by the same frameworks. Co-regulation was confirmed through gene expression analysis of brains from males exposed to LL or AP photoperiod compared to natural conditions: LL fish had suppressed gnrh1, kiss2, galr1b and esr1, while AP fish had stimulated npas2, gnrh1, gnrh2, kiss2, kiss1rb and galr1b compared to NP. It is concluded that fish exposed to different photoperiods present significant expression differences in some clock and reproductive axis related genes well before the first detectable endocrine and morphological responses of the BPG axis.

  16. Photoperiodic Modulation of Circadian Clock and Reproductive Axis Gene Expression in the Pre-Pubertal European Sea Bass Brain

    Science.gov (United States)

    Martins, Rute S. T.; Gomez, Ana; Zanuy, Silvia; Carrillo, Manuel; Canário, Adelino V. M.

    2015-01-01

    The acquisition of reproductive competence requires the activation of the brain-pituitary-gonad (BPG) axis, which in most vertebrates, including fishes, is initiated by changes in photoperiod. In the European sea bass long-term exposure to continuous light (LL) alters the rhythm of reproductive hormones, delays spermatogenesis and reduces the incidence of precocious males. In contrast, an early shift from long to short photoperiod (AP) accelerates spermatogenesis. However, how photoperiod affects key genes in the brain to trigger the onset of puberty is still largely unknown. Here, we investigated if the integration of the light stimulus by clock proteins is sufficient to activate key genes that trigger the BPG axis in the European sea bass. We found that the clock genes clock, npas2, bmal1 and the BPG genes gnrh, kiss and kissr share conserved transcription factor frameworks in their promoters, suggesting co-regulation. Other gene promoters of the BGP axis were also predicted to be co-regulated by the same frameworks. Co-regulation was confirmed through gene expression analysis of brains from males exposed to LL or AP photoperiod compared to natural conditions: LL fish had suppressed gnrh1, kiss2, galr1b and esr1, while AP fish had stimulated npas2, gnrh1, gnrh2, kiss2, kiss1rb and galr1b compared to NP. It is concluded that fish exposed to different photoperiods present significant expression differences in some clock and reproductive axis related genes well before the first detectable endocrine and morphological responses of the BPG axis. PMID:26641263

  17. Effect of exercise on photoperiod-regulated hypothalamic gene expression and peripheral hormones in the seasonal Dwarf Hamster Phodopus sungorus.

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    Ines Petri

    Full Text Available The Siberian hamster (Phodopus sungorus is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prevents or reverses body weight reduction is unknown, but one hypothesis is a reversal of short-day photoperiod induced gene expression changes in the hypothalamus that underpin body weight regulation. Alternatively, we postulate an exercise-related anabolic effect involving the growth hormone axis. To test these hypotheses we established photoperiod-running wheel experiments of 8 to 16 weeks duration assessing body weight, food intake, organ mass, lean and fat mass by magnetic resonance, circulating hormones FGF21 and insulin and hypothalamic gene expression. In response to running wheel activity, short-day housed hamsters increased body weight. Compared to short-day housed sedentary hamsters the body weight increase was accompanied by higher food intake, maintenance of tissue mass of key organs such as the liver, maintenance of lean and fat mass and hormonal profiles indicative of long day housed hamsters but there was no overall reversal of hypothalamic gene expression regulated by photoperiod. Therefore the mechanism by which activity induces body weight gain is likely to act largely independently of photoperiod regulated gene expression in the hypothalamus.

  18. Testicular steroid metabolism in juvenile bank voles (Clethrionomys glareolus Schreber) exposed to different photoperiods: an in vitro study.

    Science.gov (United States)

    Tänkä, K M; Teräväinen, T; Wallgren, H

    1983-09-01

    Juvenile male bank voles (18-22 days of age) were either sacrificed immediately (Group C) or subjected first to a long (18L:6D, lights on 0600-2400; Group L) or a short (6L:18D, lights on 0800-1400; Group S) photoperiod for 1 week. The animal were killed by decapitation, the gonads were excised, and minced, and the conversion of [4-14C]pregnenolone (delta 3P) and [4-14C]dehydroepiandrosterone (DHA) to metabolites was studied in vitro. The radioactive steroids formed were separated and identified by thin-layer chromatography (TLC). The conversion of delta 3P to C19-steroids increased markedly from 35 (Group C) to 86% (Group L) during the first week in the long photoperiod whereas in the short photoperiod a decrease to 14.42% (Group S) was observed. The reduced production of C19-steroids in the more inactive testes was accompanied by the accumulation of progesterone (delta 4P) (52.98% Group S and 24.9% Group C) and small amounts of 17 alpha-hydroxyprogesterone (17 alpha-OH-delta 4P) (2.5 and 4.5%, respectively), whereas in Group L only trace amounts of these metabolites were encountered. No marked differences in the metabolism of [4-14C]DHA between the photoperiodic groups were observed. These results seem to indicate that at least in vitro marked changes in C17-C20-lyase and/or 17 alpha-hydroxylase activities occur in this seasonally breeding species during testicular maturation and photoperiodically induced regression.

  19. Effect of Exercise on Photoperiod-Regulated Hypothalamic Gene Expression and Peripheral Hormones in the Seasonal Dwarf Hamster Phodopus sungorus

    Science.gov (United States)

    Petri, Ines; Dumbell, Rebecca; Scherbarth, Frank; Steinlechner, Stephan; Barrett, Perry

    2014-01-01

    The Siberian hamster (Phodopus sungorus) is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prevents or reverses body weight reduction is unknown, but one hypothesis is a reversal of short-day photoperiod induced gene expression changes in the hypothalamus that underpin body weight regulation. Alternatively, we postulate an exercise-related anabolic effect involving the growth hormone axis. To test these hypotheses we established photoperiod-running wheel experiments of 8 to 16 weeks duration assessing body weight, food intake, organ mass, lean and fat mass by magnetic resonance, circulating hormones FGF21 and insulin and hypothalamic gene expression. In response to running wheel activity, short-day housed hamsters increased body weight. Compared to short-day housed sedentary hamsters the body weight increase was accompanied by higher food intake, maintenance of tissue mass of key organs such as the liver, maintenance of lean and fat mass and hormonal profiles indicative of long day housed hamsters but there was no overall reversal of hypothalamic gene expression regulated by photoperiod. Therefore the mechanism by which activity induces body weight gain is likely to act largely independently of photoperiod regulated gene expression in the hypothalamus. PMID:24603871

  20. Diurnal profiles of hypothalamic energy balance gene expression with photoperiod manipulation in the Siberian hamster, Phodopus sungorus.

    Science.gov (United States)

    Ellis, Claire; Moar, Kim M; Logie, Tracy J; Ross, Alexander W; Morgan, Peter J; Mercer, Julian G

    2008-04-01

    Hypothalamic energy balance genes have been examined in the context of seasonal body weight regulation in the Siberian hamster. Most of these long photoperiod (LD)/short photoperiod (SD) comparisons have been of tissues collected at a single point in the light-dark cycle. We examined the diurnal expression profile of hypothalamic genes in hamsters killed at 3-h intervals throughout the light-dark cycle after housing in LD or SD for 12 wk. Gene expression of neuropeptide Y, agouti-related peptide, proopiomelanocortin, cocaine- and amphetamine-regulated transcript, long-form leptin receptor, suppressor of cytokine signaling-3, melanocortin-3 receptor, melanocortin-4 receptor, and the clock gene Per1 as control were measured by in situ hybridization in hypothalamic nuclei. Effects of photoperiod on gene expression and leptin levels were generally consistent with previous reports. A clear diurnal variation was observed for Per1 in the suprachiasmatic nucleus in both photoperiods. Temporal effects on expression of energy balance genes were restricted to long-form leptin receptor in the arcuate nucleus and ventromedial nucleus, where similar diurnal expression profiles were observed, and melanocortin-4 receptor in the paraventricular nucleus; these effects were only observed in LD hamsters. There was no variation in serum leptin concentration. The 24-h profiles of hypothalamic energy balance gene expression broadly confirm photoperiodic differences that were observed previously, based on single time point comparisons, support the growing consensus that these genes have a limited role in seasonal body weight regulation, and further suggest limited involvement in daily rhythms of food intake.

  1. Photoperiod regulates genes encoding melanocortin 3 and serotonin receptors and secretogranins in the dorsomedial posterior arcuate of the Siberian hamster.

    Science.gov (United States)

    Nilaweera, K N; Archer, Z A; Campbell, G; Mayer, C-D; Balik, A; Ross, A W; Mercer, J G; Ebling, F J P; Morgan, P J; Barrett, P

    2009-02-01

    The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster are currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study aimed to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified several photoperiodically regulated genes in the dmpARC that are known to have roles in secretory and intracellular signalling pathways. These include secretogranin (sg) III and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signalling pathway), all of which increase in expression under a short photoperiod. The spatial relationship between receptor signalling and potential secretory pathways was investigated by dual in situ hybridisation, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurones expressing VGF mRNA and that a sub-population (approximately 40%) of these neurones express MC3-R. These gene expression changes in dmpARC neurones may reflect the functional requirement of these neurones for seasonal physiological responses of the hamster.

  2. Photoperiod and acute energy deficits interact on components of the thyroid hormone system in hypothalamic tanycytes of the Siberian hamster.

    Science.gov (United States)

    Herwig, Annika; Wilson, Dana; Logie, Tracy J; Boelen, Anita; Morgan, Peter J; Mercer, Julian G; Barrett, Perry

    2009-05-01

    In the Siberian hamster, seasonal weight loss occurs gradually over many weeks during autumn and winter. This is driven by a regulatory mechanism that is able to integrate duration of exposure to short days (SDs) with the size of body energy reserves. After food restriction in SDs, followed by ad libitum refeeding, body weight of the hamster does not return to its former level; rather, it increases to a level defined by the length of time spent in SDs. In this report, we show that components of the thyroid hormone system that are involved in seasonal weight loss change expression in response to 48 h of starvation. Eight weeks in an SD photoperiod induced weight loss in the Siberian hamster. In the hypothalamus of these hamsters, type II deiodinase expression was decreased and type III deiodinase expression was induced, but there was no change in hypothalamic neuropeptide Y or thyrotropin-releasing hormone gene expression. For the first time, we show that the thyroid hormone transporter monocarboxylate transporter 8 is expressed in tanycytes and is increased in response to an SD photoperiod. Food restriction (48 h of starvation) reversed the direction of gene expression change for type II and III deiodinase and monocarboxylate transporter 8 induced by SD photoperiods. Furthermore, fasting increased neuropeptide Y expression and decreased thyrotropin-releasing hormone expression. VGF, a gene upregulated in SDs in the dorsal region of the medial posterior area of the arcuate nucleus, was not changed by starvation. These data point to a mechanism whereby energy deprivation can interact with an SD photoperiod on hypothalamic tanycytes to regulate components of the thyroid hormone system involved in photoperiodic regulation of seasonal physiology.

  3. MULTILATERAL DIPLOMACY AND INTERNATIONAL REGIMES

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    BENEA Ciprian-Beniamin

    2014-12-01

    Full Text Available The history of diplomacy can by divided in three main periods: one is that of occasional diplomacy peculiar to Middle Ages, while other belong to permane diplomacy, peculiar to modern times. But this one can be divided in two parts, too: one with a bilateral character, previos to 1st World War, and one with a multilateral character, manifested especially after the end on 1st World War. This third type is the focus of present paper. And it cannot be separated from the newly international constructs: international regimes, and international organizations. International instritutions the area where international regimes are belonging to – are legal constructs which provide the formal (and legal framework for continous negotiations. They are the most visible part of the new diplomacy – the one which has a permanent character, and it has an more open face. Anyway, the most important connection has to do with the international institutions, international regimes, and multilateral international negotiations. In the era of the new diplomacy, they all have a permanent character. International institutions help international negotiations carring on; while in their turn, they provide the base for international regimes’ creation, and especially for their evolution. The international regimes’ evolution is an inseparable part of a permanent international framework. And if there is missing a permanent international framework (international organization connected to a specific regime, this regime is a difuse one, its members have only informal relations among them, while they survey each other, looking at their behavior, but they don’t have a formal relationship among them, which could help them solving their future common interests, and protect them from their common fears. International regimes are very important in the era when evrithing touches, and influences everything. In the same time, the complexity of our present world can be successfully

  4. Great Lakes' regional climate regimes

    Science.gov (United States)

    Kravtsov, Sergey; Sugiyama, Noriyuki; Roebber, Paul

    2016-04-01

    We simulate the seasonal cycle of the Great Lakes' water temperature and lake ice using an idealized coupled lake-atmosphere-ice model. Under identical seasonally varying boundary conditions, this model exhibits more than one seasonally varying equilibrium solutions, which we associate with distinct regional climate regimes. Colder/warmer regimes are characterized by abundant/scarce amounts of wintertime ice and cooler/warmer summer temperatures, respectively. These regimes are also evident in the observations of the Great Lakes' climate variability over recent few decades, and are found to be most pronounced for Lake Superior, the deepest of the Great Lakes, consistent with model predictions. Multiple climate regimes of the Great Lakes also play a crucial role in the accelerated warming of the lakes relative to the surrounding land regions in response to larger-scale global warming. We discuss the physical origin and characteristics of multiple climate regimes over the lakes, as well as their implications for a longer-term regional climate variability.

  5. Effects of photoperiod on reproduction of Siamese fighting fish Betta splendens

    OpenAIRE

    Luiz Gustavo Giannecchini; Haluko Massago; João Batista Kochenborger Fernandes

    2012-01-01

    This study investigated the effect of different photoperiods (24 h of light (L):0 h of darkness (D); 20L:4D; 16L:8D; 12L:12D; and 8L:16D) on the reproduction and growth of Betta splendens. The results showed that spawning frequency was significantly higher in couples reared under 16L:8D and 12L:12D, in comparison with other treatments. The highest number of eggs per spawn was obtained under 16L:8D (544.76±375.23) and 12L:12D (471.13±261.52), and the lowest values were detected for 24L:0D (128...

  6. Photoperiod affects distribution of dynorphin A in the brain of Siberian hamster.

    Science.gov (United States)

    Meyza, Ksenia Z; Sotowska-Brochocka, Jolanta

    2006-01-01

    Dynorphin A1-77 (DYN A1-17) acting in the CNS is known to affect thermoregulation, water and energy balance in the short time scale. In this study a long-term alteration of these functions induced by changes of day length in the highly photoperiodic species, the Siberian hamster (Phodopus sungorus) was studied using immunohistochemistry for DYN A1-17. We found that in the long day (LD, L:D 16 h:8 h) more brain areas express DYN A1-17 peptide than in the short day (SD, L:D 8 h:16 h) conditions. Structures of the hypothalamo-pituitary axis as well as cells of the ependyma, subcomissural organ and choroid plexus of the lateral and third brain ventricles are immunoreactive to anti-dynorphin IgG only in the LD. This might indicate a seasonal regulatory role of DYN A1-17 in physiological adaptations to severe climate changes.

  7. Photoperiod and cold night temperature in control of flowering in Kalanchoë

    DEFF Research Database (Denmark)

    Lopes Coelho, Lívia; Kuligowska, Katarzyna; Lütken, Henrik Vlk

    2015-01-01

    Kalanchoë species and cultivars are produced as ornamental plants in many places in the world. The genus contains around 140 species comprising significant morphological variation, however, the number of species used for breeding is limited due to lack of knowledge of e.g., flower inducing factors....... Having both parental plants flowering at the same time is vital for croßpollination; therefore, it is of significant importance to be able to control flowering time of the species of interest. The objective of this study was to control flower induction in K. marmorata and K. longiflora. K. prittwitzii...... was used as control species to validate treatments that consisted of combining short day photoperiod (8 h) and different night temperature (18, 12 and 6C). While K. prittwitzii had 100% flowering for all treatments, K. marmorata only flowered at 12C (33% plants flowering) and 6C (25% plants flowering...

  8. Labile phytochrome and photoperiodic flower induction in Pharbitis nil Chois. The irreversible phytochrome hypothesis

    Directory of Open Access Journals (Sweden)

    Mariusz Cymerski

    2014-01-01

    Full Text Available Seedlings of Pharbitis nil cultivated under non-inductive conditions of white light were subjected to generative induction applying one 16-hour-long period of inductive night. During the eighth hour the night was interrupted with 1 min of red light pulse which completely inhibited the flowering. Treating the plants with KCN blocked the inhibiting effect of red light. Because KCN lowers considerably the rate of destruction of labile Pfd in some plant systems, it seems probable that red light night-break irradiation (without KCN, which blocked the flowering, leads also to the accumulation of unknown Pfd destruction products (irreversible phytochrome. It also suggests that it is not the labile PfrI itself but the products of its irreversible transformation that could be active in the photoperiodic control of flowering.

  9. Effect of photoperiod, light intensity and carbon sources on biomass and lipid productivities of Isochrysis galbana.

    Science.gov (United States)

    Babuskin, Srinivasan; Radhakrishnan, Kesavan; Babu, Packirisamy Azhagu Saravana; Sivarajan, Meenakshisundaram; Sukumar, Muthusamy

    2014-08-01

    Biomass and lipid productivities of Isochrysis galbana were optimized using nutrients of molasses (4, 8, 12 g l(-1)), glucose (4, 8, 12 g l(-1)), glycerol (4, 8, 12 g l(-1)) and yeast extract (2 g l(-1)). Combinations of carbon sources at different ratios were evaluated in which the alga was grown at three different light intensities (50, 100 and 150 μmol m(-2) s(-1)) under the influence of three different photoperiod cycles (12/12, 18/6 and 24/0 h light/dark). A maximum cell density of 8.35 g l(-1) with 32 % (w/w) lipid was achieved for mixotrophic growth at 100 μmol m(-2) s(-1) and 18/6 h light/dark with molasses/glucose (20:80 w/w). Mixotrophic cultivation using molasses, glucose and glycerol was thus effective for the cultivation of I. galbana.

  10. Photoperiod sensitivity of the Arabidopsis circadian clock is tissue-specific.

    Science.gov (United States)

    Shimizu, Hanako; Araki, Takashi; Endo, Motomu

    2015-01-01

    Tissue-specific functions of the circadian clock in Arabidopsis have recently been revealed. The vasculature clock shows distinctive gene expression profiles compared to the clock in other tissues under light-dark cycles. However, it has not yet been established whether the vasculature clock also shows unique gene expression patterns that correlate with temperature cycles, another important environmental cue. Here, we detected diel phase of TIMING OF CAB EXPRESSION 1 (TOC1) expression in the vasculature and whole leaf under long-day light-dark cycles and temperature cycles. We found that the vasculature clock had advanced TOC1 phase under light-dark cycles but not under temperature cycles, suggesting that the vasculature clock has lower sensitivity against temperature signals. Furthermore, the phase advancement of TOC1 was seen only under long-day condition but not under short-day condition. These results support our previous conclusion that the circadian clock in vasculature preferentially senses photoperiodic signals.

  11. A few aspects of the physiology of flowering in photoperiodic sensitive plants

    Directory of Open Access Journals (Sweden)

    E. G. Groenewald

    2003-09-01

    Full Text Available Three aspects of the physiology of flowering in photoperiodic sensitive plants are discussed. These are the florigen hypothesis, phytochrome and the time measurement mechanism of flowering and genetic-molecular studies involved in flowering. There is evidence that the hypothetical compound, florigen, occurs in plants, but it has never been characterised. There is a family of phytochromes discovered in plants and some of them are involved with the circadian clock and thus with the time measurement mechanism of flowering. The molecular networks that interact to control flowering are being elucidated, by means of genetic-molecular techniques although at an early stage. It has not yet been possible to pinpoint florigen by these methods, but the future looks promising.

  12. Friction Regimes in the Lubricants Solid-State Regime

    NARCIS (Netherlands)

    Schipper, D.J.; Maathuis, O.; Dowson, D.; Taylor, C.M.; Childs, T.H.C.; Dalmaz, G.

    1995-01-01

    Friction measurements were performed in the lubricant's solid-state regime to study the transition from full-film lubrication, in which the separation is maintained by a solidified lubricant, to mixed lubrication. Special attention is paid to the influence of temperature (inlet viscosity) and roughn

  13. Effects of photoperiod on kisspeptin neuronal populations of the ewe diencephalon in connection with reproductive function.

    Science.gov (United States)

    Chalivoix, S; Bagnolini, A; Caraty, A; Cognié, J; Malpaux, B; Dufourny, L

    2010-02-01

    Kisspeptin (Kiss) is a key regulator of reproductive function in both prepubertal and adult mammals. Its expression appears to vary throughout the year in seasonal species. We aimed to determine the impact of a change of photoperiod on the size of Kiss neuronal populations found in the preoptic area (POA) and arcuate nucleus (ARC) of the ewe brain. Using immunocytochemistry, we first examined the proportion of neurones expressing Kiss, using HuC/D as a neuronal marker, at different time-points after transition from long days (LD; 16 : 8 h light/dark cycle) to short days (SD; 8 : 16 h light/dark cycle). Luteinising hormone (LH) secretion was measured in ovariectomised oestradiol replaced ewes from the month preceding the transition to SD until the sacrifice of the animals at days 0, 45 and 112 from this photoperiodic transition. High LH levels were only observed in animals killed at day 112. The number of Kiss neurones/mm(2) doubled in the caudal ARC at day 112. The percentage of neurones showing Kiss immunoreactivity increased significantly in both the POA and ARC in the day 112 group. In a second experiment, ewes kept in LD received an i.c.v. injection of colchicine 20 h before sacrifice. Colchicine treatment increased the number and the percentage of neurones with Kiss in both the POA and caudal ARC. The data obtained suggest that the increase in Kiss neurones detected in the POA and caudal ARC after transition to SD stemmed from an increase in Kiss synthesis. This up-regulation of Kiss content under the shorter day condition appears to be a late event within the cascade activated by a longer secretion of melatonin, which is a critical factor in switching gonadotrophin-releasing hormone secretion to a breeding season profile.

  14. Dormancy and the Influence of photoperiod and temperature on sexual maturity in Nicrophorus nepalensis (Coleoptera: Silphidae)

    Institute of Scientific and Technical Information of China (English)

    Wenbe Hwang; Shiuh-Feng Shiao

    2011-01-01

    Carrion beetles (Nicrophorus spp.) use small vertebrate carcasses for food and reproduction. Their ecology and behaviors are highly affected by the availability of carcasses and the surrounding environmental conditions. Our results revealed that in subtropical Fushan, northern Taiwan, N. nepalensis was mainly active in spring (February to May), and could also be found in autumn (October and November); but there was no capture record in summer (June to September) and winter (December and January). A laboratory temperature tolerance study indicated that N. nepalensis adults become inactive at temperatures above 26°C, and had the highest mortality when the temperature was raised from 27℃ to 28℃. Furthermore, N. nepalensis became sexually mature at 20℃, depending on the photoperiod: the longer the day, the lower the percentage of sexually mature 2-week-old females after emergence. In another experiment, N. nepalensis virgins were paired under three possible conditions at Fushan. At 15℃ and 20℃, if carcasses were presented to the pairs within 3 days after emergence, all laid eggs in the second week after emergence. If carcasses were presented 1 week after emergence, most began to reproduce at 20℃ with 12.5 h of daylight. However, at 15℃ with 11 h of daylight, the carrion beetles hibernated first, and reproduced in the ninth week after emergence. At 25℃ with 14 h of daylight, carrion beetles did not bury the mouse carcasses, the females did not lay eggs, and the adult lifespan was only one-third of that at 20℃. This study revealed that both photoperiod and temperature influence the time needed to reach the sexual maturity of N. nepalensis; and also implied that the narrow temperature tolerance range and dormancy behavior of carrion beetles are highly regulated by those environmental factors.

  15. Photoperiod: Its importance as an impeller of pineal and seasonal reproductive rhythms

    Science.gov (United States)

    Reiter, R. J.

    1980-03-01

    A number of long day breeding rodents depend on seasonal changes in photoperiodic length to synchronize their breeding seasons with the appropriate time of the year. These relationships are particularly conspicuous in the Syrian hamster where day length is vitally important in determining periods of sexual activity and inactivity. The organ in the body whose activity is most closely attuned to the photoperiodic environment is the pineal gland. During periods of darkness the biochemical and secretory activity of the pineal is enhanced with the resultant production of antigonadotrophic principles which are strongly suppressive to reproductive physiology. In this manner, decreasing day lengths of the fall are involved with suppressing sexual capability in male and female hamsters. Throughout the winter months darkness (because of the shorter day lengths and the fact that hamsters remain underground in lightless burrows) holds the gonads in an atrophic condition and thereby prevents hamsters from breeding. As spring approaches the neuroendocrine reproductive axis becomes refractory to the inhibitory effects of darkness and the pineal gland and, as a consequence, the gonads recrudesce allowing the animals to successfully reproduce. The long days of the spring and summer serve to interrupt the refractory period so that when winter approaches shortening day lengths will again, by way of the pineal gland, induce gonadalinvolution. In this scheme both light and darkness are critically important in synchronizing the phases of the annual reproductive cycle of the hamster with the appropriate season of the year. Melatonin may be the pineal hormone which mediates the effects of darkness on reproductive physiology.

  16. A long noncoding RNA regulates photoperiod-sensitive male sterility, an essential component of hybrid rice.

    Science.gov (United States)

    Ding, Jihua; Lu, Qing; Ouyang, Yidan; Mao, Hailiang; Zhang, Pingbo; Yao, Jialing; Xu, Caiguo; Li, Xianghua; Xiao, Jinghua; Zhang, Qifa

    2012-02-14

    Hybrid rice has greatly contributed to the global increase of rice productivity. A major component that facilitated the development of hybrids was a mutant showing photoperiod-sensitive male sterility (PSMS) with its fertility regulated by day length. Transcriptome studies have shown that large portions of the eukaryotic genomic sequences are transcribed to long noncoding RNAs (lncRNAs). However, the potential roles for only a few lncRNAs have been brought to light at present. Thus, great efforts have to be invested to understand the biological functions of lncRNAs. Here we show that a lncRNA of 1,236 bases in length, referred to as long-day-specific male-fertility-associated RNA (LDMAR), regulates PSMS in rice. We found that sufficient amount of the LDMAR transcript is required for normal pollen development of plants grown under long-day conditions. A spontaneous mutation causing a single nucleotide polymorphism (SNP) between the wild-type and mutant altered the secondary structure of LDMAR. This change brought about increased methylation in the putative promoter region of LDMAR, which reduced the transcription of LDMAR specifically under long-day conditions, resulting in premature programmed cell death (PCD) in developing anthers, thus causing PSMS. Thus, a lncRNA could directly exert a major effect on a trait like a structure gene, and a SNP could alter the function of a lncRNA similar to amino acid substitution in structural genes. Molecular elucidating of PSMS has important implications for understanding molecular mechanisms of photoperiod regulation of many biological processes and also for developing male sterile germplasms for hybrid crop breeding.

  17. Evidence of a molecular clock in the ovine ovary and the influence of photoperiod.

    Science.gov (United States)

    Murphy, B A; Blake, C M; Brown, J A; Martin, A-M; Forde, N; Sweeney, L M; Evans, A C O

    2015-07-15

    The influence of the central circadian clock on reproductive timing is well established. Much less is known about the role of peripheral oscillators such as those in the ovary. We investigated the influence of photoperiod and timing of the LH surge on expression of circadian clock genes and genes involved in steroidogenesis in ovine ovarian stroma. Seventy-two Suffolk cross ewes were divided into two groups, and their estrous cycles were synchronized. Progestagen sponge removal was staggered by 12 hours between the groups such that expected LH peak would occur midway through either the light or dark phase of the photoperiodic cycle. Four animals from each group were killed, and their ovaries were harvested beginning 36 hours after sponge removal, at 6-hour intervals for 48 hours. Blood was sampled every 3 hours for the period 24 to 48 hours after sponge removal to detect the LH surge. The interval to peak LH did not differ between the groups (36.2 ± 1.2 and 35.6 ± 1.1 hours, respectively). There was an interaction between group and the time of sponge removal on the expression of the core clock genes ARNTL, PER1, CRY1, CLOCK, and DBP (P < 0.01, P < 0.05, P < 0.01, P < 0.01, and P < 0.01, respectively). As no significant interaction between group and time of day was detected, the datasets were combined. Statistically significant rhythmic oscillation was observed for ARNTL, CLOCK, CRY1 (P < 0.01, respectively), PTGS2, DBP, PTGER2, and CYP17A1 (P < 0.05, respectively), confirming the existence of a time-sensitive functionality within the ovary, which may influence steroidogenesis and is independent of the ovulatory cycle.

  18. On the regimes of premixing

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, S.; Theofanous, T.G.; Yuen, W.W. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

    1998-01-01

    The conditions of the MAGICO-2000 experiment are extended to more broadly investigate the regimes of premixing, and the corresponding internal structures of mixing zones. With the help of the data and numerical simulations using the computer code PM-ALPHA, we can distinguish extremes of behavior dominated by inertia and thermal effects - we name these the inertia and thermal regimes, respectively. This is an important distinction that should guide future experiments aimed at code verification in this area. Interesting intermediate behaviors are also delineated and discussed. (author)

  19. Feeding Your Baby

    Medline Plus

    Full Text Available ... Baby Feeding your baby Other Baby topics ') document.write(' Caring for your baby ') document.write('') } ') document.write(' Feeding your baby ') document.write('') } ') document. ...

  20. Feeding tube - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

  1. Jejunostomy feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000181.htm Jejunostomy feeding tube To use the sharing features on this ... vomiting Your child's stomach is bloated Alternate Names Feeding - jejunostomy tube; G-J tube; J-tube; Jejunum ...

  2. Nasogastric feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000182.htm Nasogastric feeding tube To use the sharing features on this ... the nose. It can be used for all feedings or for giving a person extra calories. It ...

  3. Feeding Your Newborn

    Science.gov (United States)

    ... for your child. These guidelines on breastfeeding and bottle feeding can help you make the decision that's right ... formula is a nutritious alternative to breast milk. Bottle feeding can offer more freedom and flexibility for moms, ...

  4. Monetary regimes in open economies

    NARCIS (Netherlands)

    Korpos, A.

    2006-01-01

    This thesis presents a two-country open economy framework for the analysis of strategic interactions among monetary authorities and wage bargaining institutions. From this perspective, the thesis investigates the economic consequences of replacing flexible and fixed exchange rate regimes with a mone

  5. N-acetyltransferase (nat) is a critical conjunct of photoperiodism between the circadian system and endocrine axis in Antheraea pernyi.

    Science.gov (United States)

    Mohamed, Ahmed A M; Wang, Qiushi; Bembenek, Jadwiga; Ichihara, Naoyuki; Hiragaki, Susumu; Suzuki, Takeshi; Takeda, Makio

    2014-01-01

    Since its discovery in 1923, the biology of photoperiodism remains a mystery in many ways. We sought the link connecting the circadian system to an endocrine switch, using Antheraea pernyi. PER-, CLK- and CYC-ir were co-expressed in two pairs of dorsolateral neurons of the protocerebrum, suggesting that these are the circadian neurons that also express melatonin-, NAT- and HIOMT-ir. The results suggest that a melatonin pathway is present in the circadian neurons. Melatonin receptor (MT2 or MEL-1B-R)-ir in PTTH-ir neurons juxtaposing clock neurons suggests that melatonin gates PTTH release. RIA showed a melatonin rhythm with a peak four hours after lights off in adult brain both under LD16:8 (LD) and LD12:12 (SD), and both the peak and the baseline levels were higher under LD than SD, suggesting a photoperiodic influence. When pupae in diapause were exposed to 10 cycles of LD, or stored at 4 °C for 4 months under constant darkness, an increase of NAT activity was observed when PTTH released ecdysone. DNA sequence upstream of nat contained E-boxes to which CYC/CLK could bind, and nat transcription was turned off by clk or cyc dsRNA. dsRNA(NAT) caused dysfunction of photoperiodism. dsRNA(PER) upregulated nat transcription as anticipated, based on findings in the Drosophila melanogaster circadian system. Transcription of nat, cyc and clk peaked at ZT12. RIA showed that dsRNA(NAT) decreased melatonin while dsRNA(PER) increased melatonin. Thus nat, a clock controlled gene, is the critical link between the circadian clock and endocrine switch. MT-binding may release PTTH, resulting in termination of diapause. This study thus examined all of the basic functional units from the clock: a photoperiodic counter as an accumulator of mRNA(NAT), to endocrine switch for photoperiodism in A. pernyi showing this system is self-complete without additional device especially for photoperiodism.

  6. N-acetyltransferase (nat is a critical conjunct of photoperiodism between the circadian system and endocrine axis in Antheraea pernyi.

    Directory of Open Access Journals (Sweden)

    Ahmed A M Mohamed

    Full Text Available Since its discovery in 1923, the biology of photoperiodism remains a mystery in many ways. We sought the link connecting the circadian system to an endocrine switch, using Antheraea pernyi. PER-, CLK- and CYC-ir were co-expressed in two pairs of dorsolateral neurons of the protocerebrum, suggesting that these are the circadian neurons that also express melatonin-, NAT- and HIOMT-ir. The results suggest that a melatonin pathway is present in the circadian neurons. Melatonin receptor (MT2 or MEL-1B-R-ir in PTTH-ir neurons juxtaposing clock neurons suggests that melatonin gates PTTH release. RIA showed a melatonin rhythm with a peak four hours after lights off in adult brain both under LD16:8 (LD and LD12:12 (SD, and both the peak and the baseline levels were higher under LD than SD, suggesting a photoperiodic influence. When pupae in diapause were exposed to 10 cycles of LD, or stored at 4 °C for 4 months under constant darkness, an increase of NAT activity was observed when PTTH released ecdysone. DNA sequence upstream of nat contained E-boxes to which CYC/CLK could bind, and nat transcription was turned off by clk or cyc dsRNA. dsRNA(NAT caused dysfunction of photoperiodism. dsRNA(PER upregulated nat transcription as anticipated, based on findings in the Drosophila melanogaster circadian system. Transcription of nat, cyc and clk peaked at ZT12. RIA showed that dsRNA(NAT decreased melatonin while dsRNA(PER increased melatonin. Thus nat, a clock controlled gene, is the critical link between the circadian clock and endocrine switch. MT-binding may release PTTH, resulting in termination of diapause. This study thus examined all of the basic functional units from the clock: a photoperiodic counter as an accumulator of mRNA(NAT, to endocrine switch for photoperiodism in A. pernyi showing this system is self-complete without additional device especially for photoperiodism.

  7. Effects of photoperiod on growth of and denitrification by Pseudomonas chlororaphis in the root zone of Glyceria maxima, studied in a gnotobiotic microcosm

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Wijlhuizen, A.G.; Blom, C.W.P.M.; Laanbroek, H.J.

    1997-01-01

    The emergent macrophyte Glyceria maxima was subjected to different photoperiods and grown with ammonium or nitrate as nitrogen source in presterilized microcosms with spatially separated root and non-root compartments. The microcosms were inoculated with the denitrifying bacterium Pseudomonas

  8. Two-phase photoperiodic cultivation of algal-bacterial consortia for high biomass production and efficient nutrient removal from municipal wastewater.

    Science.gov (United States)

    Lee, Chang Soo; Oh, Hyung-Seok; Oh, Hee-Mock; Kim, Hee-Sik; Ahn, Chi-Yong

    2016-01-01

    This study investigated the photoperiodic effects on the biomass production and nutrient removal in the algal-bacterial wastewater treatment, under the following three conditions: (1) a natural 12h:12h LD cycle, (2) a dark-elongated 12h:60h LD cycle, and (3) a two-phase photoperiodic 12h:60h LD, followed by 12h:12h LD cycles. The two-phase photoperiodic operation showed the highest dry cell weight and lipid productivity (282.6mgL(-1)day(-1), 71.4mgL(-1)day(-1)) and most efficient nutrient removals (92.3% COD, 95.8% TN, 98.1% TP). The genetic markers and sequencing analyses indicated rapid increments of bacteria, subsequent growths of Scenedesmus, and stabilized population balances between algae and bacteria. In addition, the two-phase photoperiod provided a higher potential for the algal-bacterial consortia to utilize various organic carbon substrates.

  9. Growth and palmitoleic acid accumulation of filamentous oleaginous microalgae Tribonema minus at varying temperatures and light regimes.

    Science.gov (United States)

    Wang, Hui; Gao, Lili; Zhou, Wenjun; Liu, Tianzhong

    2016-10-01

    Palmitoleic acid (C16:1Δ9), contributes greatly to human health, industrial chemicals and biodiesel. The filamentous oleaginous microalgae Tribonema sp. has been identified as a highly efficient producer of palmitoleic acid. Temperature and light regime were adapted to regulate the palmitoleic acid content in this study. Strain T. minus was able to grow well at all the tested temperatures, even at 5 °C. The optimum temperature for palmitoleic acid accumulation (54.25 % of total fatty acid) was 25 °C. Moreover, both light intensity and photoperiod affect the growth, lipid content and fatty acid files of T. minus. The culture exposed to 240 μmol photons m(-2) s(-1) with a photoperiod of 24:0 showed the highest biomass (6.87 g L(-1)) and biggest lipid content (61.27 % of dry weight), whereas the most amount of palmitoleic acid (50.47 % of total fatty acid) was detected at 120 μmol photons m(-2) s(-1). These findings make tangible contributions to culture T. minus for commercial production of lipid or palmitoleic acid.

  10. Breast-Feeding Twins: Making Feedings Manageable

    Science.gov (United States)

    ... more than one baby? Here's help breast-feeding twins or other multiples, from getting positioned and ensuring ... babies who are born prematurely, as are many twins and higher order multiples. Breast milk is easier ...

  11. Feed safety in the feed supply chain

    Directory of Open Access Journals (Sweden)

    Pinotti, L.

    2011-01-01

    Full Text Available A number of issues have weakened the public's confidence in the quality and wholesomeness of foods of animal origin. As a result farmers, nutritionists, industry and governments have been forced to pay serious attention to animal feedstuff production processes, thereby acknowledging that animal feed safety is an essential prerequisite for human food safety. Concerns about these issues have produced a number of important effects including the ban on the use of processed animal proteins, the ban on the addition of most antimicrobials to farm animals diets for growth‐promotion purposes, and the implementation of feed contaminant regulations in the EU. In this context it is essential to integrate knowledge on feed safety and feed supply. Consequently, purchase of new and more economic sources of energy and protein in animal diets, which is expected to conform to adequate quality, traceability, environmental sustainability and safety standards, is an emerging issue in livestock production system.

  12. Association of the circadian rhythmic expression of GmCRY1a with a latitudinal cline in photoperiodic flowering of soybean

    OpenAIRE

    2008-01-01

    Photoperiodic control of flowering time is believed to affect latitudinal distribution of plants. The blue light receptor CRY2 regulates photoperiodic flowering in the experimental model plant Arabidopsis thaliana. However, it is unclear whether genetic variations affecting cryptochrome activity or expression is broadly associated with latitudinal distribution of plants. We report here an investigation of the function and expression of two cryptochromes in soybean, GmCRY1a and GmCRY2a. Soybea...

  13. Reproductive allochrony in seasonally sympatric populations maintained by differential response to photoperiod: Implications for population divergence and response to climate change

    Science.gov (United States)

    Fudickar, A.M.; Grieves, T.J.; Atwell, Jonathan W.; Stricker, Craig A.; Ketterson, Ellen D.

    2016-01-01

    Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in response to supplementary or photoperiodic cues and whether the response varies in relation to the distance separating breeding and wintering locations as measured by stable isotopes. We held seasonally sympatric migratory and sedentary male dark-eyed juncos (Junco hyemalis) in a common garden in early spring under simulated natural changes in photoperiod and made measurements of reproductive and migratory physiology. On the same dates and photoperiods, sedentary juncos had higher testosterone (initial and gonadotropin-releasing hormone induced), more developed cloacal protuberances, and larger testes than migrants. In contrast, migratory juncos had larger fat reserves (fuel for migration). We found a negative relationship between testis mass and feather hydrogen isotope ratios, indicating that testis growth was more delayed in migrants making longer migrations. We conclude that reproductive allochrony in seasonally sympatric migratory and sedentary birds can result from a differential response to photoperiodic cues in a common garden, and as a result, gene flow between migrants and residents may be reduced by photoperiodic control of reproductive development. Further, earlier breeding in response to future climate change may currently be constrained by differential response to photoperiodic cues.

  14. Reproductive Allochrony in Seasonally Sympatric Populations Maintained by Differential Response to Photoperiod: Implications for Population Divergence and Response to Climate Change.

    Science.gov (United States)

    Fudickar, Adam M; Greives, Timothy J; Atwell, Jonathan W; Stricker, Craig A; Ketterson, Ellen D

    2016-04-01

    Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in response to supplementary or photoperiodic cues and whether the response varies in relation to the distance separating breeding and wintering locations as measured by stable isotopes. We held seasonally sympatric migratory and sedentary male dark-eyed juncos (Junco hyemalis) in a common garden in early spring under simulated natural changes in photoperiod and made measurements of reproductive and migratory physiology. On the same dates and photoperiods, sedentary juncos had higher testosterone (initial and gonadotropin-releasing hormone induced), more developed cloacal protuberances, and larger testes than migrants. In contrast, migratory juncos had larger fat reserves (fuel for migration). We found a negative relationship between testis mass and feather hydrogen isotope ratios, indicating that testis growth was more delayed in migrants making longer migrations. We conclude that reproductive allochrony in seasonally sympatric migratory and sedentary birds can result from a differential response to photoperiodic cues in a common garden, and as a result, gene flow between migrants and residents may be reduced by photoperiodic control of reproductive development. Further, earlier breeding in response to future climate change may currently be constrained by differential response to photoperiodic cues.

  15. Robust and flexible response of the Ostreococcus tauri circadian clock to light/dark cycles of varying photoperiod.

    Science.gov (United States)

    Thommen, Quentin; Pfeuty, Benjamin; Corellou, Florence; Bouget, François-Yves; Lefranc, Marc

    2012-09-01

    The green microscopic alga Ostreococcus tauri has recently emerged as a promising model for understanding how circadian clocks, which drive the daily biological rhythms of many organisms, synchronize to the day/night cycle in changing weather and seasons. Here, we analyze translational reporter time series data for the central clock genes CCA1 and TOC1 for a wide range of daylight durations (photoperiods). The variation of temporal expression profiles with day duration is complex, with the two protein peaks tracking different times of the day. Nevertheless, all profiles are accurately reproduced by a simple two-gene transcriptional loop model whose parameters depend on light only through the photoperiod value. We show that this non-intuitive behavior allows the circadian clock to combine flexibility and robustness with respect to daylight fluctuations.

  16. Exchange rate regimes and monetary arrangements

    Directory of Open Access Journals (Sweden)

    Ivan Ribnikar

    2005-06-01

    Full Text Available There is a close relationship between a country’s exchange rate regime and monetary arrangement and if we are to examine monetary arrangements then exchange rate regimes must first be analysed. Within the conventional and most widely used classification of exchange rate regimes into rigid and flexible or into polar regimes (hard peg and float on one side, and intermediate regimes on the other there, is a much greater variety among intermediate regimes. A more precise and, as will be seen, more useful classification of exchange rate regimes is the first topic of the paper. The second topic is how exchange rate regimes influence or determine monetary arrangements and monetary policy or monetary policy regimes: monetary autonomy versus monetary nonautonomy and discretion in monetary policy versus commitment in monetary policy. Both topics are important for countries on their path to the EU and the euro area

  17. The Concept of Truth Regime

    Directory of Open Access Journals (Sweden)

    Lorna Weir

    2008-07-01

    Full Text Available “Truth regime” is a much used but little theorized concept, with the Foucauldian literature presupposing that truth in modernity is uniformly scientific/quasi-scientific and enhances power. I argue that the forms of truth characteristic of our present are wider than Foucault recognized, their relations to power more various, and their historicity more complex. The truth regime of advanced modernity is characterized by multiple, irreducible truth formulae that co-exist and sometimes vie for dominance. A truth formula stabilizes a network of elements: a relation between representation and presentation (words and things, truth and non-truth, and the place of the subject in discourse. Our contemporary truth regime comprises radically heterogeneous truthful knowledges – science, governance, religion/politics, and common culture – that have distinct histories and relations to power.

  18. Influence of different artificial lighting regimes on intraocular pressure circadian profile in the dog (Canis familiaris).

    Science.gov (United States)

    Piccione, Giuseppe; Giannetto, Claudia; Fazio, Francesco; Giudice, Elisabetta

    2010-01-01

    The present study was undertaken to determine the temporal variation in intraocular pressure (IOP) and if this variation is under circadian clock control. The authors exposed five female and five male Beagles to four different artificial lighting regimes: 12/12 light/dark (L/D) period, 12/12 D/L period, constant light, and constant darkness. IOP was measured at 3 h intervals over a 48-h period. Statistical analysis of the data was performed by multivariate ANOVA, one-way repeated measure ANOVA and by the single cosinor method. Results showed no statistical effect of gender, eye and photoperiod on IOP values. A significant effect of time for each gender and each eye during all lighting regimes was seen, except during constant light, and also robust daily rhythmicity of IOP values in all L/D periods, except during constant light. In conclusion IOP values in the dog show a circadian rhythm and this rhythm is driven by a central pacemaker.

  19. Effect of Exercise on Photoperiod-Regulated Hypothalamic Gene Expression and Peripheral Hormones in the Seasonal Dwarf Hamster Phodopus sungorus

    OpenAIRE

    Ines Petri; Rebecca Dumbell; Frank Scherbarth; Stephan Steinlechner; Perry Barrett

    2014-01-01

    The Siberian hamster (Phodopus sungorus) is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prev...

  20. Seasonal changes of photoperiodic response and inflorescence quality in pot cultivars of Chrysanthemum × grandiflorum grown in greenhouse

    Directory of Open Access Journals (Sweden)

    Marek Jerzy

    2012-12-01

    Full Text Available The aim of the research was to investigate seasonal changes of photoperiodic response and inflorescence quality in chrysanthemum from the Time group grown all year round without supplementary lighting. Four chrysanthemum cultivars were grown in 12 cycles starting on the second day of each successive month. The first cycle began on 2 January. From the moment of potting, the plants were treated with a short day. In periods of naturally long days, the day was shortened to 10.5 hours through shading. No supplementary illumination was used from November to mid-February (a photoperiod of under 10 hours to improve light conditions in the period of insolation deficit. In Polish climatic conditions, the shortest photoperiodic responses were recorded usually in the cycles starting in February or March and August or September. An exceptionally longer photoperiodic response was recorded in the cycle including the height of summer, i.e. planting from June to July, when the temperature during the day was very high, and from October to December i.e. in the period of substantial insolation deficit. The highest quality of flower heads was attained by plants potted mostly between 2 March and 2 September and flowering from April - May to November. Those plants developed the greatest number of inflorescences and usually a typical, cultivar-specific colour of the flower. Chrysanthemums potted from 2 June to 2 July, i.e. in the period of the greatest heat, produced inflorescences with the smallest diameter. For the cultivar 'Cool Time', this unfavorable period lasted from 2 April to 2 August.

  1. Interacting effects of photoperiod and photosynthetic photon flux on net carbon assimilation and starch accumulation in potato leaves

    Science.gov (United States)

    Stutte, G. W.; Yorio, N. C.; Wheeler, R. M.

    1996-01-01

    The effect of photoperiod (PP) on net carbon assimilation rate (Anet) and starch accumulation in newly mature canopy leaves of 'Norland' potato (Solanum tuberosum L.) was determined under high (412 varies as mol m-2s-1) and low (263 varies as mol m-2s-1) photosynthetic photon flux (PPF) conditions. The Anet decreased from 13.9 to 11.6 and 9.3 micromoles m-2s-1, and leaf starch increased from 70 to 129 and 118 mg g-1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in Anet. Photoperiod did not affect either the CO2 compensation point (50 micromoles mol-1) or CO2 saturation point (1100-1200 micromoles mol-1) for Anet. These results show an apparent limit to the amount of starch that can be stored (approximately 15% DM) in potato leaves. An apparent feedback mechanism exists for regulating Anet under high PPF, high CO2, and long PP, but there was no correlation between Anet and starch concentration in individual leaves. This suggests that maximum Anet cannot be sustained with elevated CO2 conditions under long PP (> or = 12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon,then increasing photoperiod and light intensity under high CO2 conditions is not the most appropriate means to maximize the yield of potatoes.

  2. Multiple effects of circadian dysfunction induced by photoperiod shifts: alterations in context memory and food metabolism in the same subjects.

    Science.gov (United States)

    McDonald, Robert J; Zelinski, Erin L; Keeley, Robin J; Sutherland, Dylan; Fehr, Leah; Hong, Nancy S

    2013-06-13

    Humans exposed to shiftwork conditions have been reported to have increased susceptibility to various health problems including various forms of dementia, cancer, heart disease, and metabolic disorders related to obesity. The present experiments assessed the effects of circadian disruption on learning and memory function and various food related processes including diet consumption rates, food metabolism, and changes in body weight. These experiments utilized a novel variant of the conditioned place preference task (CPP) that is normally used to assess Pavlovian associative learning and memory processes produced via repeated context-reward pairings. For the present experiments, the standard CPP paradigm was modified in that both contexts were paired with food, but the dietary constituents of the food were different. In particular, we were interested in whether rats could differentiate between two types of carbohydrates, simple (dextrose) and complex (starch). Consumption rates for each type of carbohydrate were measured throughout training. A test of context preference without the food present was also conducted. At the end of behavioral testing, a fasting glucose test and a glucose challenge test were administered. Chronic photoperiod shifting resulted in impaired context learning and memory processes thought to be mediated by a neural circuit centered on the hippocampus. The results also showed that preferences for the different carbohydrate diets were altered in rats experiencing photoperiod shifting in that they maintained an initial preference for the simple carbohydrate throughout training. Lastly, photoperiod shifting resulted in changes in fasting blood glucose levels and elicited weight gain. These results show that chronic photoperiod shifting, which likely resulted in circadian dysfunction, impairs multiple functions of the brain and/or body in the same individual. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  3. Effect of photoperiod on slow and fast developing individuals in aphidophagous ladybirds, Menochilus sexmaculatus and Propylea dissecta (Coleoptera: Coccinellidae).

    Science.gov (United States)

    Singh, Neha; Mishra, Geetanjali; Omkar

    2016-02-01

    The effects of environmental parameters on insect development have been studied extensively. But the reasons for 2 differential developmental rates within same cohort under varying environmental factors have not been explored. For the purpose, in this study the existence and stability of slow and fast development under 5 photoperiods (i.e., 8L: 16D, 10L : 14D, 12L : 12D, 14L : 10D and 16L : 8D; light and dark hours per day) and its effect on body mass and reproductive attributes in 2 aphidophagous ladybirds, Menochilus sexmaculatus (Fabricius) and Propylea dissecta (Mulsant) was examined on Aphis craccivora Koch at 27 ± 1 °C temperature. A clear bimodal (2 peaks, where the first peak represented the fast developing and the 2nd peak slow developing individuals) pattern of distribution at each photoperiod was found. The proportion of slow and fast developing individuals in a cohort differed with photoperiods. The slow developing individuals were more in numbers at 8L : 16D, in equal numbers at 14L : 10D and in less numbers at 16L: 8D, indicating that the variation in emergence was owing to exogenous cues influenced differential rates of mortality. Slow developing individuals had female biased sex ratio, higher longevity and lower body mass than fast developing individuals. Fast developing females laid higher numbers of eggs with higher egg viability than slow developing females. Study of such variations in development at different photoperiods is helpful to understand its role in the development of insects particularly ladybirds and permits the selection of fast developing bioagents for their use in biocontrol of pest species. © 2014 Institute of Zoology, Chinese Academy of Sciences.

  4. Circadian photosensitive phase and photoperiodic control of testis activity in the mink, a short-day mammal

    Energy Technology Data Exchange (ETDEWEB)

    Boissin-Agasse, L.; Boissin, J.; Ortavant, R.

    1982-02-01

    Evidence of a circadian photosensitive phase in male mink, whose annual reproductive cycle is characterized by the recrudescence of testicular development in autumn, was based on the study of testicular response after interrupting the dark period by light breaks offered at various times. In this mammal, the experimental short days 4L:20D and 8L:16D stimulated testicular growth. Short photoperiods, including a main light period of 3.5 h and an additional 0.5 h light break 7.5 h after the beginning of the main photoperiod, were as effective as 8L:16D in stimulating testicular development. On the other hand, when a 0.5 h light break occurred 11.5 or 15.5 h after the beginning of the main photoperiod, the same inhibiting effect on testicular activity was obtained as for long photoperiods. However, when 0.5 h light breaks were given 19.5 after the beginning of the main light period, some minks recognized, as, the onset of the shorter of the two light periods offered. Thus our results proved the existence of a special phase in the day cycle in which light inhibited testicular development in the mink which appears to be a short-day animal. One explanation of the difference between long-day and short-day animals would be the following: if for long-day animals exposure to light during the photosensitive phase led to gonadostimulation, in short-day mammals, like mink, it exerted an inhibiting influence on testicular growth.

  5. Solar rhythm in the regulation of photoperiodic flowering of long-day and short-day plants.

    Science.gov (United States)

    Yeang, Hoong-Yeet

    2013-07-01

    In photoperiodic flowering, long-day (LD) plants are induced to flower seasonally when the daylight hours are long, whereas flowering in short-day (SD) plants is promoted under short photoperiods. According to the widely accepted external coincidence model, flowering occurs in LD Arabidopsis when the circadian rhythm of the gene CONSTANS (CO) peaks in the afternoon, when it is light during long days but dark when the days are short. Nevertheless, extending this explanation to SD flowering in rice, Oriza sativa, requires LD and SD plants to have 'opposite light requirements' as the CO orthologue in rice, HEADING-DATE1 (Hd1), promotes flowering only under short photoperiods. This report proposes a role of the plant's solar rhythm in promoting seasonal flowering. The interaction between rhythmic genes entrained to the solar clock and those entrained to the circadian clock form the basis of an internal coincidence model that explains both LD and SD flowering equally well. The model invokes no presumption of opposite light requirements between LD and SD plants, and further argues against any specific requirement of either light or darkness for SD flowering. Internal coincidence predicts the inhibition of SD flowering of the rice plant by a night break (a brief interruption of light), while it also provides a plausible explanation for how a judiciously timed night break promotes Arabidopsis flowering even on short days. It is the timing of the light transitions (sunrise and sunset) rather than the duration of light or darkness per se that regulates photoperiod-controlled flowering.

  6. Evolution of CONSTANS Regulation and Function after Gene Duplication Produced a Photoperiodic Flowering Switch in the Brassicaceae.

    Science.gov (United States)

    Simon, Samson; Rühl, Mark; de Montaigu, Amaury; Wötzel, Stefan; Coupland, George

    2015-09-01

    Environmental control of flowering allows plant reproduction to occur under optimal conditions and facilitates adaptation to different locations. At high latitude, flowering of many plants is controlled by seasonal changes in day length. The photoperiodic flowering pathway confers this response in the Brassicaceae, which colonized temperate latitudes after divergence from the Cleomaceae, their subtropical sister family. The CONSTANS (CO) transcription factor of Arabidopsis thaliana, a member of the Brassicaceae, is central to the photoperiodic flowering response and shows characteristic patterns of transcription required for day-length sensing. CO is believed to be widely conserved among flowering plants; however, we show that it arose after gene duplication at the root of the Brassicaceae followed by divergence of transcriptional regulation and protein function. CO has two close homologs, CONSTANS-LIKE1 (COL1) and COL2, which are related to CO by tandem duplication and whole-genome duplication, respectively. The single CO homolog present in the Cleomaceae shows transcriptional and functional features similar to those of COL1 and COL2, suggesting that these were ancestral. We detect cis-regulatory and codon changes characteristic of CO and use transgenic assays to demonstrate their significance in the day-length-dependent activation of the CO target gene FLOWERING LOCUS T. Thus, the function of CO as a potent photoperiodic flowering switch evolved in the Brassicaceae after gene duplication. The origin of CO may have contributed to the range expansion of the Brassicaceae and suggests that in other families CO genes involved in photoperiodic flowering arose by convergent evolution.

  7. Dual role of tree florigen activation complex component FD in photoperiodic growth control and adaptive response pathways.

    Science.gov (United States)

    Tylewicz, Szymon; Tsuji, Hiroyuki; Miskolczi, Pál; Petterle, Anna; Azeez, Abdul; Jonsson, Kristoffer; Shimamoto, Ko; Bhalerao, Rishikesh P

    2015-03-10

    A complex consisting of evolutionarily conserved FD, flowering locus T (FT) proteins is a regulator of floral transition. Intriguingly, FT orthologs are also implicated in developmental transitions distinct from flowering, such as photoperiodic control of bulbing in onions, potato tuberization, and growth cessation in trees. However, whether an FT-FD complex participates in these transitions and, if so, its mode of action, are unknown. We identified two closely related FD homologs, FD-like 1 (FDL1) and FD-like 2 (FDL2), in the model tree hybrid aspen. Using gain of function and RNAi-suppressed FDL1 and FDL2 transgenic plants, we show that FDL1 and FDL2 have distinct functions and a complex consisting of FT and FDL1 mediates in photoperiodic control of seasonal growth. The downstream target of the FT-FD complex in photoperiodic control of growth is Like AP1 (LAP1), a tree ortholog of the floral meristem identity gene APETALA1. Intriguingly, FDL1 also participates in the transcriptional control of adaptive response and bud maturation pathways, independent of its interaction with FT, presumably via interaction with abscisic acid insensitive 3 (ABI3) transcription factor, a component of abscisic acid (ABA) signaling. Our data reveal that in contrast to its primary role in flowering, FD has dual roles in the photoperiodic control of seasonal growth and stress tolerance in trees. Thus, the functions of FT and FD have diversified during evolution, and FD homologs have acquired roles that are independent of their interaction with FT.

  8. Circadian rhythms of feeding, oviposition, and emergence of the boll weevil (Coleoptera: Curculionidae)

    Institute of Scientific and Technical Information of China (English)

    SHOIL M.GREENBERG; J.SCOTT ARMSTRONG; MAMOUDOU S(E)TAMOU; THOMAS W.SAPPINGTON; RANDY J.COLEMAN; TONG-XIAN LIU

    2006-01-01

    Circadian rhythm of feeding,oviposition,and emergence of boll weevil adults were determined at five different photophases (24,14,12,10,and 0 hours) and a constant 27℃ temperature,65% RH in the laboratory. Squares from Petri dishes,where they were exposed to boll weevil females,were removed and examined for feeding and oviposition punctures every 4 hours during daylight (0700-1900 h) and every 12 h at night (1900-0700 h) over eight consecutive days. Cohorts of randomly selected egg-punctured squares were sampled from ovipositing females at 0700,1100,1500,and 1900 during 24 hours and under different photophase treatments,and maintained in Petri dishes at 27 ± 1℃,65% RH.Dishes were observed twice daily (1900 and 0700 h) for adults emerging at day or night.Circadian rhythm of oviposition was not affected by the length of the photophase. The boll weevil has round-the-clock circadian rhythm of oviposition,with a daytime preference. We observed that 82.4%-86.0% of the boll weevil eggs were deposited between 0700 and 1900 h,and 14.0%-17.6% between 1900 and 0700 h during a 24-h period. Feeding of boll weevil females in photoperiods 24:0 h (complete light) and 0:24 h (complete darkness) did not significantly change between 0700-1900 h versus 1900-0700 h,while the daily cycle of light and darkness in other photoperiods significantly increased the feeding punctures from 0700-1900 compared with 1900-0700 h. The circadian rhythm of emergence depended significantly on the time of oviposition and the length of the photophase. Investigation of boll weevil circadian rhythm provides a better understanding of boll weevil ecology and reveals potential weak links for improving control technologies targeting their reproductive strategies.

  9. Detecting spatial regimes in ecosystems

    Science.gov (United States)

    Sundstrom, Shana M.; Eason, Tarsha; Nelson, R. John; Angeler, David G.; Barichievy, Chris; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance; Knutson, Melinda; Nash, Kirsty L.; Spanbauer, Trisha; Stow, Craig A.; Allen, Craig R.

    2017-01-01

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

  10. The animal feed and energy conservation properties of Avotan (Avoparcin)

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, C.W. [Strathclyde Univ., Glasgow (United Kingdom); O`Beirne, P. [Cyanamid (United Kingdom) Ltd. (United Kingdom). Animal Health Div.

    1994-12-31

    AVOTAN, avoparcin is a glycopeptide antibiotic manufactured by Cyanamid (UK) via the fermentation of a strain of Streptomyces candidus. The gross energy requirement of manufacturing avoparcin is calculated and compared with the gross energy savings of feed utilisation when used in animal feeding regimes for broiler chickens, pigs, beef cattle and dairy cows for milk production. Avoparcin improves farm animal production in terms of liveweight gains and feed conversion efficiency. So, by conserving animal feed it conserves the energy which would have been expended to produce that animal feed. The energy savings thus calculated range from one to two orders of magnitude on an energy ratio basis and so are very significant. The widespread use of avoparcin in world agriculture is therefore very beneficial in an energy conservation context. (Author)

  11. In vitro effect of substrate, temperature and photoperiod on Phakopsora pachyrhizi urediniospore germination and germ tube growth

    Directory of Open Access Journals (Sweden)

    Marta Maria Casa Blum

    2015-06-01

    Full Text Available In vitro experiments were conducted to assess the effects of substrate, temperature and time of exposure to temperature and photoperiod on P. pachyrhizi uredospore germination and germ tube growth. The following substrates were tested: water-agar and soybean leaf extract-agar at different leaf concentrations (0.5, 1.0, 2.0 and 4.0 g of leaves and 15g agar/L water, temperatures (10, 15, 20, 25, 30, and 35oC and times of exposure (1, 2, 3, 4, 5, 6, 7, and 8 hours to temperature and 12 different photoperiods. The highest germination and germ tube length was found for the soybean leaf extract agar. Maximum P. pachyrhizi uredospore germination was obtained at 21.8 and 22.3°C, and maximum germ tube growth at 21.4 and 22.1°C. The maximum uredospore germination was found at 6.4 hours exposure, while the maximum germ tube length was obtained at 7.7 h exposure. Regarding photoperiod, the maximum spore germination and the maximum uredospore germ tube length were found in the dark. Neither spore germination nor uredospore germ tube growth was completely inhibited by the exposure to continuous light.

  12. Photoperiod-Dependent Effects of 4-tert-Octylphenol on Adherens and Gap Junction Proteins in Bank Vole Seminiferous Tubules

    Directory of Open Access Journals (Sweden)

    Anna Hejmej

    2013-01-01

    Full Text Available In the present study we evaluated in vivo and in vitro effects of 4-tert-octylphenol (OP on the expression and distribution of adherens and gap junction proteins, N-cadherin, β-catenin, and connexin 43 (Cx43, in testes of seasonally breeding rodents, bank voles. We found that in bank vole testes expression and distribution of N-cadherin, β-catenin, and Cx43 were photoperiod dependent. Long-term treatment with OP (200 mg/kg b.w. resulted in the reduction of junction proteins expressions (P<0.05, P<0.01 and their delocalization in the testes of males kept in long photoperiod, whereas in short-day animals slight increase of Cx43 (P<0.05, N-cadherin, and β-catenin (statistically nonsignificant levels was observed. Effects of OP appeared to be independent of FSH and were maintained during in vitro organ culture, indicating that OP acts directly on adherens and gap junction proteins in the testes. An experiment performed using an antiestrogen ICI 182,780 demonstrated that the biological effects of OP on β-catenin and Cx43 involve an estrogen receptor-mediated response. Taken together, in bank vole organization of adherens and gap junctions and their susceptibility to OP are related to the length of photoperiod. Alterations in cadherin/catenin and Cx43-based junction may partially result from activation of estrogen receptor α and/or β signaling pathway.

  13. Short photoperiod-induced decrease of histamine H3 receptors facilitates activation of hypothalamic neurons in the Siberian hamster.

    Science.gov (United States)

    Barrett, P; van den Top, M; Wilson, D; Mercer, J G; Song, C K; Bartness, T J; Morgan, P J; Spanswick, D

    2009-08-01

    Nonhibernating seasonal mammals have adapted to temporal changes in food availability through behavioral and physiological mechanisms to store food and energy during times of predictable plenty and conserve energy during predicted shortage. Little is known, however, of the hypothalamic neuronal events that lead to a change in behavior or physiology. Here we show for the first time that a shift from long summer-like to short winter-like photoperiod, which induces physiological adaptation to winter in the Siberian hamster, including a body weight decrease of up to 30%, increases neuronal activity in the dorsomedial region of the arcuate nucleus (dmpARC) assessed by electrophysiological patch-clamping recording. Increased neuronal activity in short days is dependent on a photoperiod-driven down-regulation of H3 receptor expression and can be mimicked in long-day dmpARC neurons by the application of the H3 receptor antagonist, clobenproprit. Short-day activation of dmpARC neurons results in increased c-Fos expression. Tract tracing with the trans-synaptic retrograde tracer, pseudorabies virus, delivered into adipose tissue reveals a multisynaptic neuronal sympathetic outflow from dmpARC to white adipose tissue. These data strongly suggest that increased activity of dmpARC neurons, as a consequence of down-regulation of the histamine H3 receptor, contributes to the physiological adaptation of body weight regulation in seasonal photoperiod.

  14. COLPOCITOLOGY AND SERUM CONCENTRATIONS OF PROGESTERONE IN NULIPAROUS GOATS SUBMMITED TO ARTIFICIAL PHOTOPERIODS COLPOCITOLOGIA E CONCENTRAÇÕES SÉRICAS DE PROGESTERONA EM CABRAS NULÍPARAS SUBMETIDAS AO FOTOPERÍODO ARTIFICIAL

    Directory of Open Access Journals (Sweden)

    Caroline Rocha de Oliveira Lima

    2008-10-01

    Full Text Available The aim of present work was to evaluate the changes of cervico-vaginal epithelial cells and progesterone levels of nuliparous goats submitted to artificial photoperiod, in Middle-West of Brazil. Seventh Alpine and six crossbreed nuliparous goats were used, distributed in two groups: control (GC, maintained at isolated stall and submitted to natural light for the time of the year, and treated (GT, submitted to an alternate regime among natural and artificial light, for 24 hours and 35 uninterrupted days. Cérvico-vaginal content was collected, prepared on glass slides and differential cellular counts were carried out on Papanicolau smears. The progesterone concentration in blood serum was measurement by ELISA. Parabasal were the most frequent cell type present, followed by intermediate cells, mainly in the end of metaestrus and diestrus. Superficial cornified cells were present during proestrus and estrus. The cellular profile and progesterone concentrations oscillated in agreement with estrus cycle phase in control animals, but confuse on the begin of experimental period for treated animals. Cytological evaluation of cervico-vaginal content could be of value for a hormonal bioassay of estrus cycle of goats submitted to artificial photoperiod just after the adaptation period.

     

    KEY WORDS: Artificial photoperiod, caprine, hormone, vaginal cytology.

    O objetivo do presente trabalho foi avaliar as alterações celulares do epitélio cérvico-vaginal e as concentrações de progesterona sérica em cabras nulíparas expostas ao fotoperíodo artificial, na região Centro-Oeste do Brasil. Dezessete cabras da raça Alpina e seis mestiças, nulíparas, foram aleatoriamente distribuídas em grupo-controle (GC, mantido em galpão isolado e submetido ao regime de luz natural para a época do ano, e grupo tratado (GT, submetido ao regime alternado entre luz natural e

  15. Feeding behavior of Harlequin Shrimp Hymenocera picta Dana, 1852 (Hymenoceridae on Sea Star Linckia laevigata (Ophidiasteridae

    Directory of Open Access Journals (Sweden)

    S. Prakash

    2013-09-01

    Full Text Available Caridean shrimps did not display any selective feeding regimes. However, the shrimp belongs the genus Hymenocera (Caridea: Hymenoceridae exclusively feeds on starfish, causes potential crisis to the hobbyists those wish to accommodate them in reef aquaria. The present observation deals with the documentation about the feeding behavior of Harlequin Shrimp Hymenocera picta Dana feeds on its favorite prey Blue Star Linckia laevigata (Ophidiasteridae in captivity. The upliftment continues for 30-60 minutes and feeding was initiated by removing the ambulacral feet and gonadal tissues of the Starfish.

  16. Is gastric sham feeding really sham feeding?

    Science.gov (United States)

    Sclafani, A; Nissenbaum, J W

    1985-03-01

    Rats were fitted with gastric cannulas, food deprived, and allowed to drink a sugar solution that drained out of the opened cannula; i.e., the rats sham-fed. Although this procedure is thought to prevent absorption of ingested food, it was found that the sham feeding of a 32% glucose or sucrose solution significantly elevated blood glucose levels. The addition of acarbose, a drug that inhibits the digestion of sucrose, to the 32% sucrose solution blocked the blood glucose rise, as did closing the pylorus with an inflatable pyloric cuff. Neither the drug nor the cuff, however, reduced the amount of sucrose solution consumed. These findings indicate that gastric sham feeding does not necessarily prevent the digestion and absorption of food, although absorption is not essential for the appearance of a vigorous sham-feeding response. Nevertheless the possibility that neural or hormonal feedback from the stomach contributes to the sham-feeding response cannot be excluded, and until this issue is resolved the results of gastric sham-feeding studies should be interpreted with caution.

  17. Complex Feeding Decisions

    Directory of Open Access Journals (Sweden)

    Anna Miles PhD

    2016-08-01

    Full Text Available Objective: Where swallowing difficulties are chronic or progressive, or a patient is palliative, tube feeding is often not deemed appropriate. Instead, patients continue to eat and drink despite the risks of pneumonia and death. There is currently little evidence to guide clinical practice in this field often termed “risk feeding.” This qualitative study investigated staff, patient, and family member perceptions of risk feeding practices in one New Zealand hospital. Method: Twenty-nine staff members and six patients and/or their family were interviewed. Results: Thematic analysis revealed four global themes: supporting practice, communication, complexity of feeding decisions, and patient and family-centered care. Staff described limited education and organizational policy around risk feeding decisions. Communication was considered a major factor in the success. Conclusion: Feeding decisions are complex in the hospital environment. The themes identified in this study provide a foundation for hospital guideline development and implementation.

  18. Feeding behavior of Harlequin Shrimp Hymenocera picta Dana, 1852 (Hymenoceridae) on Sea Star Linckia laevigata (Ophidiasteridae)

    OpenAIRE

    Prakash, S.; T.T.A. Kumar

    2013-01-01

    Caridean shrimps did not display any selective feeding regimes. However, the shrimp belongs the genus Hymenocera (Caridea: Hymenoceridae) exclusively feeds on starfish, causes potential crisis to the hobbyists those wish to accommodate them in reef aquaria. The present observation deals with the documentation about the feeding behavior of Harlequin Shrimp Hymenocera picta Dana feeds on its favorite prey Blue Star Linckia laevigata (Ophidiasteridae) in captivity. The upliftment continues for 3...

  19. Post-pyloric feeding

    Institute of Scientific and Technical Information of China (English)

    Eva Niv; Zvi Fireman; Nachum Vaisman

    2009-01-01

    Postpyloric feeding is an important and promising alternative to parenteral nutrition. The indications for this kind of feeding are increasing and include a variety of clinical conditions, such as gastroparesis, acute pancreatitis, gastric outlet stenosis, hyperemesis (including gravida), recurrent aspiration, tracheoesophageal fistula and stenosis in gastroenterostomy. This review discusses the differences between pre- and postpyloric feeding, indications and contraindications, advantages and disadvantages, and provides an overview of the techniques of placement of various postpyloric devices.

  20. Infant feeding: formula, solids.

    Science.gov (United States)

    Barness, L A

    1985-04-01

    This article discusses and evaluates current formulas, traces their continual improvement (based largely on new information on breast milk composition), and then discusses the question of supplemental feedings.

  1. Danger of zooplankton feeding

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, H.; Colin, S.P.

    2010-01-01

    Zooplankton feed in any of three ways: they generate a feeding current while hovering, cruise through the water or are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly and ther......Zooplankton feed in any of three ways: they generate a feeding current while hovering, cruise through the water or are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly...

  2. Effects of CO2 Concentration on Leaf Photosynthesis and Stomatal Conductance of Potatoes Grown Under Different Irradiance Levels and Photoperiods

    Science.gov (United States)

    Wheeler, R. M.; Fitzpatrick, A. H.; Tibbitts, T. W.

    2012-01-01

    Potato (Solanum tuberosum L.) cvs. Russet Burbank, Denali, and Norland, were grown in environmental rooms controlled at approx 350 micro mol/mol (ambient during years 1987/1988) and 1000 micro mol/mol (enriched) CO2 concentrations. Plants and electric lamps were arranged to provide two irradiance zones, 400 and 800 micro mol/mol/square m/S PPF and studies were repeated using two photoperiods (12-h light / 12-h dark and continuous light). Leaf photosynthetic rates and leaf stomatal conductance were measured using fully expanded, upper canopy leaves at weekly intervals throughout growth (21 through 84 days after transplanting). Increasing the CO2 from approx 350 to 1000 micro mol/mol under the 12-h photoperiod increased leaf photosynthetic rates by 39% at 400 micro mol/mol/square m/S PPF and 27% at 800 micro mol/mol/square m/S PPF. Increasing the CO2 from approx 350 to 1000 micro mol/mol under continuous light decreased leaf photosynthetic rates by 7% at 400 micro mol/mol/square m/S PPF and 13% at 800 micro mol/mol/square m/S PPF. Increasing the CO2 from approx 350 to 1000 micro mol/mol under the 12-h photoperiod plants decreased stomatal conductance by an average of 26% at 400 micro mol/mol/square m/S PPF and 42% at 800 micro mol/mol/square m/S PPF. Under continuous light, CO2 enrichment resulted in a small increase (2%) of stomatal conductance at 400 micro mol/mol/square m/S PPF, and a small decrease (3%) at 800 micro mol/mol/square m/S PPF. Results indicate that CO2 enrichment under the 12-h photoperiod showed the expected increase in photosynthesis and decrease in stomatal conductance for a C3 species like potato, but the decreases in leaf photosynthetic rates and minimal effect on conductance from CO2 enrichment under continuous light were not expected. The plant leaves under continuous light showed more chlorosis and some rusty flecking versus plants under the 12-h photoperiod, suggesting the continuous light was more stressful on the plants. The increased

  3. Water stress, CO2 and photoperiod influence hormone levels in wheat

    Science.gov (United States)

    Nan, Rubin; Carman, John G.; Salisbury, Frank B.; Campbell, W. F. (Principal Investigator)

    2002-01-01

    'Super Dwarf' wheat (Triticum aestivum L.) plants have been grown from seed to maturity in the Mir space station where they were periodically exposed, because of microgravity and other constraints, to water deficit, waterlogging, high CO2 levels, and low light intensities. The plants produced many tillers, but none of them produced viable seed. Studies have been initiated to determine why the plants responded in these ways. In the present study, effects of the listed stresses on abscisic acid (ABA), indole-3-acetic acid (IAA) and isopentenyl adenosine ([9R]iP) levels in roots and leaves of plants grown under otherwise near optimal conditions on earth were measured. Hormones were extracted, purified by HPLC, and quantified by noncompetitive indirect ELISA. In response to water deficit, ABA levels increased in roots and leaves, IAA levels decreased in roots and leaves, and [9R]iP levels increased in leaves but decreased in roots. In response to waterlogging, ABA, IAA and [9R]iP levels briefly increased in roots and leaves and then decreased. When portions of the root system were exposed to waterlogging and/or water deficit, ABA levels in leaves increased while [9R]iP and IAA levels decreased. These responses were correlated with the percentage of the root system stressed. At a low photosynthetic photon flux (100 micromoles m-2 s-1), plants grown in continuous light had higher leaf ABA levels than plants grown using an 18 or 21 h photoperiod.

  4. Water stress, CO2 and photoperiod influence hormone levels in wheat

    Science.gov (United States)

    Nan, Rubin; Carman, John G.; Salisbury, Frank B.; Campbell, W. F. (Principal Investigator)

    2002-01-01

    'Super Dwarf' wheat (Triticum aestivum L.) plants have been grown from seed to maturity in the Mir space station where they were periodically exposed, because of microgravity and other constraints, to water deficit, waterlogging, high CO2 levels, and low light intensities. The plants produced many tillers, but none of them produced viable seed. Studies have been initiated to determine why the plants responded in these ways. In the present study, effects of the listed stresses on abscisic acid (ABA), indole-3-acetic acid (IAA) and isopentenyl adenosine ([9R]iP) levels in roots and leaves of plants grown under otherwise near optimal conditions on earth were measured. Hormones were extracted, purified by HPLC, and quantified by noncompetitive indirect ELISA. In response to water deficit, ABA levels increased in roots and leaves, IAA levels decreased in roots and leaves, and [9R]iP levels increased in leaves but decreased in roots. In response to waterlogging, ABA, IAA and [9R]iP levels briefly increased in roots and leaves and then decreased. When portions of the root system were exposed to waterlogging and/or water deficit, ABA levels in leaves increased while [9R]iP and IAA levels decreased. These responses were correlated with the percentage of the root system stressed. At a low photosynthetic photon flux (100 micromoles m-2 s-1), plants grown in continuous light had higher leaf ABA levels than plants grown using an 18 or 21 h photoperiod.

  5. Effect of photoperiod on serum hormone concentrations during the annual reproductive cycle in geese.

    Science.gov (United States)

    Zhao, X Z; Gao, G L; Wang, H W; Li, Q; Zhang, K S; Zhong, H; Wang, Q G

    2017-03-22

    The poor egg-laying rate of geese hinders the development of the goose industry; therefore, the reproductive performance of geese is an important area of investigation. To evaluate the relationship between photoperiod, reproductive hormones, and reproductive activity during the egg-laying cycle in geese under natural conditions, we collected blood samples from Sichuan white geese and Xupu geese to quantify changes in prolactin (PRL), estradiol (E2), vasoactive intestinal polypeptide (VIP), follicle stimulating hormone (FSH), gonadotropin-inhibitory hormone (GnIH), and luteinizing hormone (LH). We also calculated the rate of egg laying for the two populations during the egg-laying cycle. We show that the egg-laying rate and the serum concentration of some hormones (PRL, E2, VIP, FSH, GnIH, and LH) differed significantly between the two populations during the pre-laying, laying, and ceased-laying periods. Serum LH concentrations may be associated with maturation of the ovary and oviducts, whereas FSH, PRL, and GnIH play important roles in egg laying. These results provide a useful resource for future studies examining the laying rate in geese.

  6. Development of photoperiod- and thermo-sensitive male sterility rice expressing transgene Bacillus thuringiensis

    Science.gov (United States)

    Liu, Xin; Zhang, Jiwen; Zhang, Cuicui; Wang, Liangchao; Chen, Hao; Zhu, Zengrong; Tu, Jumin

    2015-01-01

    Stem borers and leaffolders are the main pests that cause severe damage in rice (Oryza sativa L.) production worldwide. We developed the first photoperiod- and thermo-sensitive male sterility (PTSMS) rice 208S with the cry1Ab/1Ac Bacillus thuringiensis (Bt) gene, through sexual crossing with Huahui 1 (elite line with the cry1Ab/1Ac gene). The novel 208S and its hybrids presented high and stable resistance to stem borers and leaffolders, and the content of Cry1Ab/1Ac protein in chlorophyllous tissues achieved the identical level as donor and showed little accumulation in non-chlorophyllous tissue. No dominant dosage effect in the Bt gene was observed in 208S and its derived hybrids. An analysis of fertility transition traits indicated that 208S was completely sterile under long day length/high temperature, but partially fertile under short day length/low temperature. With fine grain quality and favorable combining ability, 208S had no observed negative effects on fertility and agronomic traits from Bt (cry1Ab/1Ac). Additionally, 208S as a male sterile line showed no fertility decrease caused by Bt transgenic process, as it is the case in Huahui 1. Thus, 208S has great application value in two-line hybrid production for insect resistance, and can also be used as a bridge material in rice Bt transgenic breeding. PMID:26366116

  7. Effects of Photoperiod on the Haematological Parameters of Clarias Gariepinus Fingerlings Reared in Water Recirculatory System

    Directory of Open Access Journals (Sweden)

    Solomon S.G.

    2012-08-01

    Full Text Available Haematological analyses has been routinely used in determining the physiological state of animals and known to be affected by different environmental factors, the present study was therefore designed to assess the effect of 24 hours of light (00D: 24L, 24 hours of darkness (24D: 00L and 12 hour light / 12 hours darkness (12D: 12L photoperiod on the haematological parameters of the African Catfish. At the end of the six weeks experiment, it was observed that some haematological parameters such as Mean Corpuscular Haemoglobin Concentration (MCHC, the Mean White Blood Cells (WBC, Mean Red Blood Cells (RBC, Haemoglobin content (HGB, Platelet count (PLT showed significant difference (P0.05. However MCHC and MCH were noticed to increase as the light period increased while the other parameters reduced as the light period increased. The findings indicate that exposure of the African Catfish to continuous light for six weeks duration elicits response in the haematological profile of the fish.

  8. Identifying and mapping cDNA fragments related to rice photoperiod sensitive genic male sterility

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The differentially expressed cDNA fragments have been obtained by differential screening with cDNA-RAPD technique in photoperiod sensitive genic male sterile (PGMS) rice.Some of them have been reassessed with Northern blot hybridization,from which a PGMS-related positive fragment,RPG43,has been identified.Further analysis on RPG43 with Southern blot and RAPD indicates that the fragment is a single-copy sequence and its mRNA has been processed after transcription.Sequence analysis reveals that RPG43 is 744 bp in length and contains a 60 bp region (from 126th to 185th bp) showing 72% homology to a human DNA sequence,pac pDJ- 356d6,on chromosome 11.So it is a new sequence found in plant and its GenBank access number is AF126027.In addition,RPG43 has been mapped to a position 3.8 cM away from RFLP marker R1553 on chromosome 5 of rice.

  9. Sulfuric Acid Pretreatment and Enzymatic Hydrolysis of Photoperiod Sensitvie Sorghum for Ethanol Production

    Energy Technology Data Exchange (ETDEWEB)

    F Xu; Y Shi; X Wu

    2011-12-31

    Photoperiod sensitive (PS) sorghum, with high soluble sugar content, high mass yield and high drought tolerance in dryland environments, has great potential for bioethanol production. The effect of diluted sulfuric acid pretreatment on enzymatic hydrolysis was investigated. Hydrolysis efficiency increased from 78.9 to 94.4% as the acid concentration increased from 0.5 to 1.5%. However, the highest total glucose yield (80.3%) occurred at the 1.0% acid condition because of the significant cellulose degradation at the 1.5% concentration. Synchrotron wide-angle X-ray diffraction was used to study changes of the degree of crystallinity. With comparison of cellulosic crystallinity and adjusted cellulosic crystallinity, the crystalline cellulose decreased after low acidic concentration (0.5%) applied, but did not change significantly, as the acid concentration increased. Scanning electron microscopy was also employed to understand how the morphological structure of PS sorghum changed after pretreatment. Under current processing conditions, the total ethanol yield is 74.5% (about 0.2 g ethanol from 1 g PS sorghum). A detail mass balance was also provided.

  10. Cytological study and PCD assay on pollen development of photoperiod sensitive genic male sterile rice

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A systematic cytological comparison of the anther development of photoperiod sensitive genic male sterile (PSGMS) rice with its normal fertility counterpart was conducted.The results showed that pollen abortion in PSGMS rice occurred first no later than the pollen mother cell (PMC) stage and continued during the entire process of pollen development till pollen degradation.This abortive process was closely associated with the abnormal behavior of tapetum.Although tapetum degeneration in the PSGMS rice initiated as early as at the PMC stage,it proceeded slowly and did not complete until the breakdown of the pollen,in sharp contrast to the rapid disintegration of the tapetal layer during the late microspore to the bicellular pollen stage in the fertile rice.Such cytological observation was supported by the results of the TUNEL (TdT2 mediated dU TP Nick End Labeling)assay that detects DNA fragmentation resulting from programmed cell death (PCD),indicating that the tapetum degeneration occurs in the process of PCD.

  11. Cow feeding system versus milk utility for yoghurt manufacture

    Directory of Open Access Journals (Sweden)

    Małgorzata Jasińska

    2010-06-01

    Full Text Available Background. A cow feeding system had a significant effect on the basic parameters characterising milk technological usability. Milk from the Polish Black-and-White variety of the Holstein-Friesland cows kept in the Total Mixed Ration (TMR feeding system or on the traditional feeding regime was compared in terms of its utility for yoghurt manufacture. Material and methods. Milk samples, collected six times a year at about 2-month intervals, were assayed for density, acidity, and contents of fat, protein, and lactose. Dry matter and solid-not-fat (SNF contents were determined, as was the protein/fat ratio. Thermal stability of the milk was assessed with alcohol tests. The yoghurts manufactured (test yoghurts were assayed for acidity, acetaldehyde content, and hardness. The yoghurts were also subjected to sensory evaluation. Results. The cow feeding regime was found to have distinctly affected the composition and physico-chemical parameters of milk. Milk samples collected from cows fed in the traditional system contained more fat and dry matter than the milk yielded by the TMR-fed cattle. The latter produced milk that usually showed higher crude protein and casein contents, as well as higher SNF contents; in addition, the density of that milk was higher. Conclusions. The feeding regime did not affect, in any clear-cut way, the sensory characteristics of the test yoghurts. However, those yoghurts manufactured from the TMR-fed cow milk contained more acetaldehyde and, in most cases, showed higher hardness, compared to the yoghurts made from milk produced by the cows kept on the traditional feeding regime.

  12. Artificial long-day photoperiod in the subtropics increases milk production in goats giving birth in late autumn.

    Science.gov (United States)

    Flores, M J; Flores, J A; Elizundia, J M; Mejía, A; Delgadillo, J A; Hernández, H

    2011-03-01

    Two experiments were conducted to determine whether exposure to a photoperiod of artificial long days in autumn increased milk yield in subtropical goats milked once (Exp. I) or twice daily (Exp. II). In Exp. I, starting at d 10 of lactation, 1 group of does was kept under naturally decreasing photoperiod (DD1X; n = 8), whereas the other group was submitted to an artificial photoperiod of long days (LD1X; n = 8; 16 h light:8 h darkness). The kids were weaned 28 d after parturition, and dams were manually milked once daily. Milk yield and milk components (fat, protein, and lactose) were assessed up to 140 d of lactation. From d 0 to 28 of lactation (suckling phase), mean daily milk yield did not differ between DD1X and LD1X goats (2.3 ± 0.2 kg vs. 2.4 ± 0.2 kg; P = 0.717). However, between d 29 and 84 (early milking phase), mean daily milk yield was greater in LD1X does than in DD1X does (2.6 ± 0.1 kg vs. 2.1 ± 0.1 kg; P = 0.001). Finally, between d 85 and 140 (late milking phase), mean daily milk yield was greater in LD1X goats than in DD1X goats (P ≤ 0.05) only during the first 2 wk. In Exp. II, one group of goats was exposed to a photoperiod of naturally decreasing days (DD2X; n = 8) and another group was submitted to an artificial photoperiod of long days (LD2X; n = 7). In both groups, kids were weaned on d 28 of lactation and the dams were manually milked twice daily. During the nursing phase, mean daily milk yield did not differ between the DD2X and LD2X groups (2.5 ± 0.3 kg vs. 2.6 ± 0.2 kg; P = 0.767). In the early milking phase, mean daily milk yield was greater in LD2X than in DD2X goats (3.3 ± 0.2 kg vs. 2.8 ± 0.2 kg; P = 0.022), whereas during the late milking phase, milk yield did not differ between the 2 groups (P = 0.946). In both experiments, milk composition was not significantly influenced by exposure to long-day photoperiod. We conclude that, in subtropical female goats that start lactation in late autumn, exposure to an artificial long

  13. The january effect across volatility regimes

    OpenAIRE

    Agnani, Betty; Aray, Henry

    2007-01-01

    Using a Markov regime switching model, this article presents evidence on the well-known January effect on stock returns. The specification allows a distinction to be drawn between two regimes, one with high volatility and other with low volatility. We obtain a time-varying January effect that is, in general, positive and significant in both volatility regimes. However, this effect is larger in the high volatility regime. In sharp contrast with most previous literature we find two major result...

  14. Long-term effects of human growth hormone-releasing hormone and photoperiod on hormone release and puberty in dairy heifers.

    Science.gov (United States)

    Ringuet, H; Pelletier, G; Brazeau, P; Gaudreau, P; Guilbault, L A; Morisset, J; Couture, Y; Petitclerc, D

    1994-10-01

    Forty-eight Holstein dairy heifers (98.9 kg BW; 3 mo old) were subjected for 246 d to twice-daily s.c. injections of saline (CTL) or human growth hormone-releasing hormone (GRH; 5 micrograms/kg BW) and to photoperiods of 8 h of light (L): 16 h of dark (D) or 16L:8D according to a 2 x 2 factorial arrangement of treatments. Jugular blood samples were collected from 16 heifers at 3, 4, 8, and 11 mo of age to monitor prolactin, growth hormone, and estradiol-17 beta. Plasma progesterone concentrations were monitored weekly in all heifers as an index of puberty (> 1 ng/mL). Growth hormone release was induced by GRH (P GRH heifers. However, GRH-induced GH response was less (P GRH, photoperiod, and days of treatment on GRH-induced GH response; AUC was greater in GRH-16L:8D than in GRH-8L:16D heifers at 3 mo but less at 8 mo of age. The PRL concentrations were similar for both photoperiods at 3 mo (36.4 vs 41.7 ng/mL) and 8 mo (16.2 vs 12.8 ng/mL) of age but were greater in 16L:8D vs 8L:16D heifers at 4 mo (18.4 vs 39.3 ng/mL) and 11 mo (26.3 vs 44.1 ng/mL) of age (photoperiod x day interaction, P GRH-treated heifers (271 vs 284 kg BW; GRH x photoperiod interaction, P = .10). In conclusion, GH response is maintained throughout 8 mo of GRH treatment, and a 16L:8D photoperiod will reduce age and weight at puberty in heifers. Furthermore, refractoriness to photoperiod-induced PRL changes was detected.

  15. Effects of photoperiod and temperature on reproductive diapause in Ophraella communa (Coleoptera:Chrysomelidae), a potential biocontrol agent against Ambrosia artemisiifolia

    Institute of Scientific and Technical Information of China (English)

    Dao-Hong Zhu; Jing Zhu; Zhao-Pu Peng; Fang-Hao Wan

    2012-01-01

    To investigate the seasonal adaptation strategies of Ophraella communa to new habitats,the effects and regulation mechanisms of photoperiod and temperature on the reproductive diapause in a population collected from Changsha,Hunan were examined.Adults showed obvious reproductive diapause,which was regulated by photoperiod and temperature.At 30℃,there was no adult diapause occurring under either long-day or short-day conditions; at 25℃ the pre-oviposition period was short and fecundity was high in adult females under L:D 16:8 h,whereas under L:D 12:12 h,a few females entered reproductive diapause; at 20℃ under short-day conditions,all female adults entered diapause.The pre-oviposition period was significantly prolonged when the pupae and adults were transferred from long-days to short-days,but the day length influence was not obvious when they were transferred only in the adult stage.However,the fecundity dropped greatly no matter whether the photoperiod shifted to short-days only in the adult stage or whether the shift occurred in both the pupal and adult stage.The fecundity was extremely low when photoperiod shifted from long-days to short-days in both pupal and adult stages.This was an indication that the pupal and adult stages were the photoperiod-sensitive stage for adult reproductive diapause.This was especially true for the photoperiod in the pupal stage,which has a distinctly significant regulative effect on reproductive diapause.Additionally,this article also addresses the reason for different photoperiodic response patterns in reproductive diapause induction between the Changsha strain and the Tsukuba strain (Japan) of O.communa.

  16. Photoperiod regulates the differential expression of KiSS-1 and GPR54 in various tissues and sexes of striped hamster.

    Science.gov (United States)

    Li, S N; Xue, H L; Zhang, Q; Xu, J H; Wang, S; Chen, L; Xu, L X

    2015-10-30

    In order to investigate how photoperiod affects the expression of KiSS-1/G-protein-coupled receptor 54 (GPR54), the hypothalamus, the ovaries and testicles of the striped hamster were studied following photoperiod treatment and melatonin injection. We found that the melatonin concentration in the blood of the striped hamster was consistent with the treated photoperiods and that the photoperiod had significant effects on KiSS-1 expression, but the effect of photoperiod on GPR54 expression differed among tissues and sexes. The relative expression of KiSS-1 in the gonads of the male and female striped hamster was significantly higher than that in the hypothalamus, while the difference in GPR54 between the gonads and hypothalamus was inconsistent between the male and female striped hamster. In the striped hamster injected with melatonin, the expression level of KiSS-1 in the gonads and hypothalamus of the male and female striped hamster was significantly decreased; the expression level of GnRH in the gonads was also significantly decreased; the expression of GPR54 in the hypothalamus was increased. In the hypothalamus, a significant positive correlation existed between KiSS-1 and GnRH expression, while a negative correlation was observed between GPR54 and GnRH expression. These results suggest that the photoperiod-melatonin-KiSS-1-GnRH pathway plays an important role in the seasonal reproduction mechanism of the striped hamster. Additionally, photoperiod or melatonin may not be a direct regulatory factor of GPR54 expression.

  17. Implementation Regimes and Street-Level Bureaucrats

    DEFF Research Database (Denmark)

    Winter, Søren; T. Dinesen, Peter; J. May, Peter

    -government regimes foster greater policy commitment, attention to rules, and adherence among frontline workers than is the case for a local-government implementation regime. These lead to actions of street-level bureaucrats in central-government regimes that are more in line with national policies than those...

  18. Accommodating human values in the climate regime

    NARCIS (Netherlands)

    Cook, Rosalind; Tauschinsky, Eljalill

    2008-01-01

    The climate regime addresses one of the most important challenges facing humankind today. However, while the environmental and economic sides of the problem are well represented, it lacks the inclusion of social and human aspects. The human rights regime, in contrast, is a regime which has been esta

  19. Selection of Feed Intake or Feed Efficiency

    DEFF Research Database (Denmark)

    Veerkamp, Roel F; Pryce, Jennie E; Spurlock, Diane

    2013-01-01

    . In February 2013, the co-authors discussed how information on DMI should be incorporated in the breeding decisions. The aim of this paper is to present the overall discussion and main positions taken by the group on four topics related to feed efficiency: i) breeding goal definition; ii) biological variation...

  20. Selection of Feed Intake or Feed Efficiency

    DEFF Research Database (Denmark)

    Veerkamp, Roel F; Pryce, Jennie E; Spurlock, Diane

    2013-01-01

    . In February 2013, the co-authors discussed how information on DMI should be incorporated in the breeding decisions. The aim of this paper is to present the overall discussion and main positions taken by the group on four topics related to feed efficiency: i) breeding goal definition; ii) biological variation...

  1. Feeding biology of Cerambycids

    Science.gov (United States)

    Robert A. Haack

    2017-01-01

    There are more than 36,000 species of Cerambycidae recognized throughout the world (see Chapter 1), occurring on all continents except Antarctica (Linsley 1959). Given such numbers, it is not surprising that cerambycids display great diversity in their feeding habits. Both adults and larvae are almost exclusively phytophagous. Some adults appear not to feed at all,...

  2. Creep Feeding Beef Calves

    OpenAIRE

    2005-01-01

    Creep feeding is the managerial practice of supplying supplemental feed (usually concentrates) to the nursing calf. Milk from a lactating beef cow furnishes only about 50 percent of the nutrients that a 3-4 month-old calf needs for maximum growth.

  3. Feeding Your Baby

    Medline Plus

    Full Text Available ... Baby Caring for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications ... write(' Feeding your baby ') document.write('') } ') document.write(' Common illnesses ') document.write('') } ') document.write(' Family health & safety ') ...

  4. Adaptation in Collaborative Governance Regimes

    Science.gov (United States)

    Emerson, Kirk; Gerlak, Andrea K.

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  5. Modelling of salad plants growth and physiological status in vitamin space greenhouse during lighting regime optimization

    Science.gov (United States)

    Konovalova, Irina; Berkovich, Yuliy A.; Smolyanina, Svetlana; Erokhin, Alexei; Yakovleva, Olga; Lapach, Sergij; Radchenko, Stanislav; Znamenskii, Artem; Tarakanov, Ivan

    2016-07-01

    The efficiency of the photoautotrophic element as part of bio-engineering life-support systems is determined substantially by lighting regime. The artificial light regime optimization complexity results from the wide range of plant physiological functions controlled by light: trophic, informative, biosynthetical, etc. An average photosynthetic photon flux density (PPFD), light spectral composition and pulsed light effects on the crop growth and plant physiological status were studied in the multivariate experiment, including 16 independent experiments in 3 replicates. Chinese cabbage plants (Brassica chinensis L.), cultivar Vesnianka, were grown during 24 days in a climatic chamber under white and red light-emitting diodes (LEDs): photoperiod 24 h, PPFD from 260 to 500 µM/(m ^{2}*s), red light share in the spectrum varying from 33% to 73%, pulsed (pulse period from 30 to 501 µs) and non-pulsed lighting. The regressions of plant photosynthetic and biochemical indexes as well as the crop specific productivity in response to the selected parameters of lighting regime were calculated. Developed models of crop net photosynthesis and dark respiration revealed the most intense gas exchange area corresponding to PPFD level 450 - 500 µM/(m ^{2}*s) with red light share in the spectrum about 60% and the pulse length 30 µs with a pulse period from 300 to 400 µs. Shoot dry weight increased monotonically in response to the increasing PPFD and changed depending on the pulse period under stabilized PPFD level. An increase in ascorbic acid content in the shoot biomass was revealed when increasing red light share in spectrum from 33% to 73%. The lighting regime optimization criterion (Q) was designed for the vitamin space greenhouse as the maximum of a crop yield square on its ascorbic acid concentration, divided by the light energy consumption. The regression model of optimization criterion was constructed based on the experimental data. The analysis of the model made it

  6. Measuring the effectiveness of international environmental regimes

    Energy Technology Data Exchange (ETDEWEB)

    Helm, C.; Sprinz, D.F.

    1999-05-01

    While past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes by developing an operational rational choice calculus to evaluate actual policy simultaneously against a non-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement instrument is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects - but fall substantially short of the collective optima. (orig.)

  7. Challenges in measuring feed efficiency

    Science.gov (United States)

    The term feed efficiency is vague, and is defined differently by people. Historically, feed efficiency has been defined as the feed:gain (F:G) ratio or the inverse (G:F). Indexes have been developed to rank animals for feed efficiency. These indexes include residual feed intake (RFI) and residual...

  8. Biomimetic cilia arrays generate simultaneous pumping and mixing regimes.

    Science.gov (United States)

    Shields, A R; Fiser, B L; Evans, B A; Falvo, M R; Washburn, S; Superfine, R

    2010-09-07

    Living systems employ cilia to control and to sense the flow of fluids for many purposes, such as pumping, locomotion, feeding, and tissue morphogenesis. Beyond their use in biology, functional arrays of artificial cilia have been envisaged as a potential biomimetic strategy for inducing fluid flow and mixing in lab-on-a-chip devices. Here we report on fluid transport produced by magnetically actuated arrays of biomimetic cilia whose size approaches that of their biological counterparts, a scale at which advection and diffusion compete to determine mass transport. Our biomimetic cilia recreate the beat shape of embryonic nodal cilia, simultaneously generating two sharply segregated regimes of fluid flow: Above the cilia tips their motion causes directed, long-range fluid transport, whereas below the tips we show that the cilia beat generates an enhanced diffusivity capable of producing increased mixing rates. These two distinct types of flow occur simultaneously and are separated in space by less than 5 microm, approximately 20% of the biomimetic cilium length. While this suggests that our system may have applications as a versatile microfluidics device, we also focus on the biological implications of our findings. Our statistical analysis of particle transport identifying an enhanced diffusion regime provides novel evidence for the existence of mixing in ciliated systems, and we demonstrate that the directed transport regime is Poiseuille-Couette flow, the first analytical model consistent with biological measurements of fluid flow in the embryonic node.

  9. Hd3a, RFT1 and Ehd1 integrate photoperiodic and drought stress signals to delay the floral transition in rice.

    Science.gov (United States)

    Galbiati, Francesca; Chiozzotto, Remo; Locatelli, Franca; Spada, Alberto; Genga, Annamaria; Fornara, Fabio

    2016-09-01

    Plants show a high degree of developmental plasticity in response to external cues, including day length and environmental stress. Water scarcity in particular can interfere with photoperiodic flowering, resulting in the acceleration of the switch to reproductive growth in several species, a process called drought escape. However, other strategies are possible and drought stress can also delay flowering, albeit the underlying mechanisms have never been addressed at the molecular level. We investigated these interactions in rice, a short day species in which drought stress delays flowering. A protocol that allows the synchronization of drought with the floral transition was set up to profile the transcriptome of leaves subjected to stress under distinct photoperiods. We identified clusters of genes that responded to drought differently depending on day length. Exposure to drought stress under floral-inductive photoperiods strongly reduced transcription of EARLY HEADING DATE 1 (Ehd1), HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1), primary integrators of day length signals, providing a molecular connection between stress and the photoperiodic pathway. However, phenotypic and transcriptional analyses suggested that OsGIGANTEA (OsGI) does not integrate drought and photoperiodic signals as in Arabidopsis, highlighting molecular differences between long and short day model species. © 2016 John Wiley & Sons Ltd.

  10. Distribution of photoperiod-insensitive allele Ppd-A1a and its effect on heading time in Japanese wheat cultivars.

    Science.gov (United States)

    Seki, Masako; Chono, Makiko; Nishimura, Tsutomu; Sato, Mikako; Yoshimura, Yasuhiro; Matsunaka, Hitoshi; Fujita, Masaya; Oda, Shunsuke; Kubo, Katashi; Kiribuchi-Otobe, Chikako; Kojima, Hisayo; Nishida, Hidetaka; Kato, Kenji

    2013-09-01

    The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9-9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that 'Purple Straw' and 'Tohoku 118' were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.

  11. Beneficial Effects of Exogenous Melatonin in Acute Staphylococcus aureus and Escherichia coli Infection-Induced Inflammation and Associated Behavioral Response in Mice After Exposure to Short Photoperiod.

    Science.gov (United States)

    Bishayi, Biswadev; Adhikary, Rana; Nandi, Ajeya; Sultana, Sahin

    2016-12-01

    The administration of melatonin during acute bacterial infection was evaluated in this study. Mice pre-exposed to normal photoperiodic (NP), short photoperiodic (SP), and long photoperiodic (LP) day lengths were infected separately with live Staphylococcus aureus (5 × 10(6) cells/ml) or Escherichia coli (2.5 × 10(7) colony-forming units/ml) and treated with melatonin (10 mg/kg body weight). Behavioral studies were performed before bacterial infection and after melatonin administration. In mice pre-exposed to SP, exogenous melatonin administration resulted in better clearance of bacteria from blood and behavioral improvement. Reduced glutathione content and superoxide dismutase activities were increased, with concomitant decrease in lipid peroxidation content and catalase activities in the liver, brain, and spleen after exogenous melatonin administration. The overproduction of tumor necrosis factor-α, interferon-γ, and interleukin-6 during acute bacterial infection in mice exposed to different photoperiods was probably regulated by the administration of exogenous melatonin, by reducing neutrophil recruitment to spleen, expression of inducible nitric oxide synthase and cyclooxygenase-2 in hypothalamus, and C-reactive protein in the serum, and was also associated with improved behavioral response. Photoperiodic variations in inflammatory and oxidative stress markers might be correlated to serum melatonin and corticosterone levels. This study suggests that the administration of melatonin during SP exposure is protective in infection-induced inflammation than NP and LP exposure.

  12. SPL3/4/5 Integrate Developmental Aging and Photoperiodic Signals into the FT-FD Module in Arabidopsis Flowering.

    Science.gov (United States)

    Jung, Jae-Hoon; Lee, Hyo-Jun; Ryu, Jae Yong; Park, Chung-Mo

    2016-12-05

    Environmental sensitivity varies across developmental phases in flowering plants. In the juvenile phase, microRNA156 (miR156)-mediated repression of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE (SPL) transcription factors renders Arabidopsis plants incompetent to floral inductive signals, including long-day (LD) photoperiod. During the vegetative phase transition, which accompanies a reduction of miR156 and a concomitant elevation of its targets, plants acquire reproductive competence such that LD signals promote flowering. However, it remains largely unknown how developmental signals are associated with photoperiodic flowering. Here, we show that SPL3, SPL4, and SPL5 (SPL3/4/5) potentiate the FLOWERING LOCUS T (FT)-FD module in photoperiodic flowering. SPL3/4/5 function as transcriptional activators through the interaction with FD, a basic leucine zipper transcription factor which plays a critical role in photoperiodic flowering. SPL3/4/5 can directly bind to the promoters of APETALA1, LEAFY, and FRUITFULL, thus mediating their activation by the FT-FD complex. Our findings demonstrate that SPL3/4/5 act synergistically with the FT-FD module to induce flowering under LDs, providing a long-sought molecular knob that links developmental aging and photoperiodic flowering.

  13. Conserved CO-FT regulons contribute to the photoperiod flowering control in soybean.

    Science.gov (United States)

    Fan, Chengming; Hu, Ruibo; Zhang, Xiaomei; Wang, Xu; Zhang, Wenjing; Zhang, Qingzhe; Ma, Jinhua; Fu, Yong-Fu

    2014-01-07

    CO and FT orthologs, belonging to the BBX and PEBP family, respectively, have important and conserved roles in the photoperiod regulation of flowering time in plants. Soybean genome experienced at least three rounds of whole genome duplications (WGDs), which resulted in multiple copies of about 75% of genes. Subsequent subfunctionalization is the main fate for paralogous gene pairs during the evolutionary process. The phylogenic relationships revealed that CO orthologs were widespread in the plant kingdom while FT orthologs were present only in angiosperms. Twenty-eight CO homologous genes and twenty-four FT homologous genes were gained in the soybean genome. Based on the collinear relationship, the soybean ancestral CO ortholog experienced three WGD events, but only two paralogous gene pairs (GmCOL1/2 and GmCOL5/13) survived in the modern soybean. The paralogous gene pairs, GmCOL1/2 or GmCOL5/13, showed similar expression patterns in pair but different between pairs, indicating that they functionally diverged. GmFTL1 to 7 were derived from the same ancestor prior to the whole genome triplication (WGT) event, and after the Legume WGD event the ancestor diverged into two branches, GmFTL3/5/7 and GmFTL1/2/4/6. GmFTL7 were truncated in the N-terminus compared to other FT-lineage genes, but ubiquitously expressed. Expressions of GmFTL1 to 6 were higher in leaves at the flowering stage than that at the seedling stage. GmFTL3 was expressed at the highest level in all tissues except roots at the seedling stage, and its circadian pattern was different from the other five ones. The transcript of GmFTL6 was highly accumulated in seedling roots. The circadian rhythms of GmCOL5/13 and GmFT1/2/4/5/6 were synchronized in a day, demonstrating the complicate relationship of CO-FT regulons in soybean leaves. Over-expression of GmCOL2 did not rescue the flowering phenotype of the Arabidopsis co mutant. However, ectopic expression of GmCOL5 did rescue the co mutant phenotype. All Gm

  14. Effect of a photoperiodic green light programme during incubation on embryo development and hatch process.

    Science.gov (United States)

    Tong, Q; McGonnell, I M; Demmers, T G M; Roulston, N; Bergoug, H; Romanini, C E; Verhelst, R; Guinebretière, M; Eterradossi, N; Berckmans, D; Exadaktylos, V

    2017-08-24

    This study was conducted to evaluate the effect of a 12-h light, 12-h dark (12L : 12D) photoperiod of green light during day 1 to day 18 of incubation time, on embryo growth, hormone concentration and the hatch process. In the test group, monochromatic light was provided by a total of 204 green light-emitting diodes (522 nm) mounted in a frame which was placed above the top tray of eggs to give even spread of illumination. No light-dark cycle was used in the control group. Four batches of eggs (n=300/group per batch) from fertile Ross 308 broiler breeders were used in this experiment. The beak length and crown-rump length of embryos incubated under green light were significantly longer than that of control embryos at day 10 and day 12, respectively (Pgreen light-exposed embryos had a longer third toe length compared with control embryos at day 10, day 14 and day 17 (P=0.02). At group level (n=4 batches), light stimulation had no effect on chick weight and quality at take-off, the initiation of hatch and hatch window. However, the individual hatching time of the light exposure focal chicks (n=33) was 3.4 h earlier (P=0.49) than the control focal chicks (n=36) probably due to the change in melatonin rhythm of the light group. The results of this study indicate that green light accelerates embryo development and alters hatch-related hormones (thyroid and corticosterone), which may result in earlier hatching.

  15. Ehd4 encodes a novel and Oryza-genus-specific regulator of photoperiodic flowering in rice.

    Directory of Open Access Journals (Sweden)

    He Gao

    Full Text Available Land plants have evolved increasingly complex regulatory modes of their flowering time (or heading date in crops. Rice (Oryza sativa L. is a short-day plant that flowers more rapidly in short-day but delays under long-day conditions. Previous studies have shown that the CO-FT module initially identified in long-day plants (Arabidopsis is evolutionary conserved in short-day plants (Hd1-Hd3a in rice. However, in rice, there is a unique Ehd1-dependent flowering pathway that is Hd1-independent. Here, we report isolation and characterization of a positive regulator of Ehd1, Early heading date 4 (Ehd4. ehd4 mutants showed a never flowering phenotype under natural long-day conditions. Map-based cloning revealed that Ehd4 encodes a novel CCCH-type zinc finger protein, which is localized to the nucleus and is able to bind to nucleic acids in vitro and transactivate transcription in yeast, suggesting that it likely functions as a transcriptional regulator. Ehd4 expression is most active in young leaves with a diurnal expression pattern similar to that of Ehd1 under both short-day and long-day conditions. We show that Ehd4 up-regulates the expression of the "florigen" genes Hd3a and RFT1 through Ehd1, but it acts independently of other known Ehd1 regulators. Strikingly, Ehd4 is highly conserved in the Oryza genus including wild and cultivated rice, but has no homologs in other species, suggesting that Ehd4 is originated along with the diversification of the Oryza genus from the grass family during evolution. We conclude that Ehd4 is a novel Oryza-genus-specific regulator of Ehd1, and it plays an essential role in photoperiodic control of flowering time in rice.

  16. The Evolution of Photoperiod-Insensitive Flowering in Sorghum, A Genomic Model for Panicoid Grasses.

    Science.gov (United States)

    Cuevas, Hugo E; Zhou, Chengbo; Tang, Haibao; Khadke, Prashant P; Das, Sayan; Lin, Yann-Rong; Ge, Zhengxiang; Clemente, Thomas; Upadhyaya, Hari D; Hash, C Thomas; Paterson, Andrew H

    2016-09-01

    Of central importance in adapting plants of tropical origin to temperate cultivation has been selection of daylength-neutral genotypes that flower early in the temperate summer and take full advantage of its long days. A cross between tropical and temperate sorghums [Sorghum propinquum (Kunth) Hitchc.×S. bicolor (L.) Moench], revealed a quantitative trait locus (QTL), FlrAvgD1, accounting for 85.7% of variation in flowering time under long days. Fine-scale genetic mapping placed FlrAvgD1 on chromosome 6 within the physically largest centiMorgan in the genome. Forward genetic data from "converted" sorghums validated the QTL. Association genetic evidence from a diversity panel delineated the QTL to a 10-kb interval containing only one annotated gene, Sb06g012260, that was shown by reverse genetics to complement a recessive allele. Sb06g012260 (SbFT12) contains a phosphatidylethanolamine-binding (PEBP) protein domain characteristic of members of the "FT" family of flowering genes acting as a floral suppressor. Sb06g012260 appears to have evolved ∼40 Ma in a panicoid ancestor after divergence from oryzoid and pooid lineages. A species-specific Sb06g012260 mutation may have contributed to spread to temperate regions by S. halepense ("Johnsongrass"), one of the world's most widespread invasives. Alternative alleles for another family member, Sb02g029725 (SbFT6), mapping near another flowering QTL, also showed highly significant association with photoperiod response index (P = 1.53×10 (-)  (6)). The evolution of Sb06g012260 adds to evidence that single gene duplicates play large roles in important environmental adaptations. Increased knowledge of Sb06g012260 opens new doors to improvement of sorghum and other grain and cellulosic biomass crops.

  17. An intact dorsomedial posterior arcuate nucleus is not necessary for photoperiodic responses in Siberian hamsters.

    Science.gov (United States)

    Teubner, Brett J W; Leitner, Claudia; Thomas, Michael A; Ryu, Vitaly; Bartness, Timothy J

    2015-04-01

    Seasonal responses of many animal species are triggered by changes in daylength and its transduction into a neuroendocrine signal by the pineal gland through the nocturnal duration of melatonin (MEL) release. The precise central sites necessary to receive, transduce, and relay the short day (SD) fall-winter MEL signals into seasonal responses and changes in physiology and behavior are unclear. In Siberian hamsters, SDs trigger decreases in body and lipid mass, testicular regression and pelage color changes. Several candidate genes and their central sites of expression have been proposed as components of the MEL transduction system with considerable recent focus on the arcuate nucleus (ARC) and its component, the dorsomedial posterior arcuate nucleus (dmpARC). This site has been postulated as a critical relay of SD information through the modulation of a variety of neurochemicals/receptors important for the control of energy balance. Here the necessity of an intact dmpARC for SD responses was tested by making electrolytic lesions of the Siberian hamster dmpARC and then exposing them to either long days (LD) or SDs for 12wks. The SD typical decreases in body and fat mass, food intake, testicular volume, serum testosterone concentrations, pelage color change and increased UCP-1 protein expression (a proxy for brown adipose tissue thermogenesis) all occurred despite the lack of an intact dmpARC. Although the Siberian hamster dmpARC contains photoperiod-modulated constituents, these data demonstrate that an intact dmpARC is not necessary for SD responses and not integral to the seasonal energy- and reproductive-related responses measured here.

  18. Cyclic colour change in the bearded dragon Pogona vitticeps under different photoperiods.

    Science.gov (United States)

    Fan, Marie; Stuart-Fox, Devi; Cadena, Viviana

    2014-01-01

    The ability to change colour rapidly is widespread among ectotherms and has various functions including camouflage, communication and thermoregulation. The process of colour change can occur as an aperiodic event or be rhythmic, induced by cyclic environmental factors or regulated by internal oscillators. Despite the importance of colour change in reptile ecology, few studies have investigated the occurrence of a circadian rhythm in lizard pigmentation. Additionally, although colour change also entails changes in near-infrared reflectance, which may affect thermoregulation, little research has examined this part of the spectrum. We tested whether the bearded dragon lizard, Pogona vitticeps, displays an endogenous circadian rhythm in pigmentation changes that could be entrained by light/dark (LD) cycles and how light affected the relative change in reflectance in both ultraviolet-visible and near-infrared spectra. We subjected 11 lizards to four photoperiodic regimens: LD 12:12; LD 6:18; LD 18:6 and DD; and measured their dorsal skin reflectance at 3-hour intervals for 72 hours after a habituation period. A proportion of lizards displayed a significant rhythm under constant darkness, with maximum reflectance occurring in the subjective night. This endogenous rhythm synchronised to the different artificial LD cycles, with maximum reflectance occurring during dark phases, but did not vary in amplitude. In addition, the total ultraviolet-visible reflectance in relation to the total near-infrared reflectance was significantly higher during dark phases than during light phases. We conclude that P. vitticeps exhibits a circadian pigmentation rhythm of constant amplitude, regulated by internal oscillators and that can be entrained by light/dark cycles.

  19. Cyclic colour change in the bearded dragon Pogona vitticeps under different photoperiods.

    Directory of Open Access Journals (Sweden)

    Marie Fan

    Full Text Available The ability to change colour rapidly is widespread among ectotherms and has various functions including camouflage, communication and thermoregulation. The process of colour change can occur as an aperiodic event or be rhythmic, induced by cyclic environmental factors or regulated by internal oscillators. Despite the importance of colour change in reptile ecology, few studies have investigated the occurrence of a circadian rhythm in lizard pigmentation. Additionally, although colour change also entails changes in near-infrared reflectance, which may affect thermoregulation, little research has examined this part of the spectrum. We tested whether the bearded dragon lizard, Pogona vitticeps, displays an endogenous circadian rhythm in pigmentation changes that could be entrained by light/dark (LD cycles and how light affected the relative change in reflectance in both ultraviolet-visible and near-infrared spectra. We subjected 11 lizards to four photoperiodic regimens: LD 12:12; LD 6:18; LD 18:6 and DD; and measured their dorsal skin reflectance at 3-hour intervals for 72 hours after a habituation period. A proportion of lizards displayed a significant rhythm under constant darkness, with maximum reflectance occurring in the subjective night. This endogenous rhythm synchronised to the different artificial LD cycles, with maximum reflectance occurring during dark phases, but did not vary in amplitude. In addition, the total ultraviolet-visible reflectance in relation to the total near-infrared reflectance was significantly higher during dark phases than during light phases. We conclude that P. vitticeps exhibits a circadian pigmentation rhythm of constant amplitude, regulated by internal oscillators and that can be entrained by light/dark cycles.

  20. Hall effect in hopping regime

    Energy Technology Data Exchange (ETDEWEB)

    Avdonin, A., E-mail: avdonin@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Skupiński, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warszawa (Poland)

    2016-02-15

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.

  1. Fermented liquid feed for pigs

    OpenAIRE

    Missotten, Joris; Michiels, Joris; Ovyn, Anneke; De Smet, Stefaan; Dierick, Noël

    2010-01-01

    Since the announcement of the ban on the use of antibiotics as antimicrobial growth promoters in the feed of pigs in 2006 the investigation towards alternative feed additives has augmented considerably. Although fermented liquid feed is not an additive, but a feeding strategy, the experimental work examining its possible advantages also saw a rise. The use of fermented liquid feed (FLF) has two main advantages, namely that the simultaneous provision of feed and water may result in an alleviat...

  2. Chlorotic feeding injury by the black pecan aphid (hemiptera: aphididae) to pecan foliage promotes aphid settling and nymphal development.

    Science.gov (United States)

    Cottrell, Ted E; Wood, Bruce W; Ni, Xinzhi

    2009-04-01

    The nature of the interaction between the black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), and the chlorosis it causes to foliage of its pecan [Carya illinoinensis (Wangenh.) K. Koch)] host is poorly understood. Laboratory experiments were conducted on the settling behavior of the black pecan aphid, when provided chlorotic pecan leaf discs resulting from previous black pecan aphid feeding and nonchlorotic leaf discs, under a normal photoperiod and constant dark. Additionally, aphid development from the first instar to the adult stage was examined when nymphs were either allowed to feed on the same leaf disc or moved daily to a new, nondamaged, same age leaf disc. After 24 h, a significantly higher percentage of black pecan aphids settled on chlorotic than on nonchlorotic leaf discs, regardless of photoperiod. When starting from the first instar, nymphs that were prevented from inducing leaf chlorosis by moving daily to new, same-age leaf discs took approximately 5 d longer to complete development, had a shorter body length, and had higher mortality than when aphids remained on the same leaf disc. These results show that black pecan aphid-induced leaf chlorosis plays an important role in the interaction of the black pecan aphid with its pecan host.

  3. High irradiance responses involving photoreversible multiple photoreceptors as related to photoperiodic induction of cell division in Euglena.

    Science.gov (United States)

    Bolige, Aoen; Goto, Ken

    2007-02-01

    Little is known about the photoreceptors involved in the photoperiodism of unicellular organisms, which we elucidated by deriving their action spectra. The flagellated alga Euglena gracilis exhibits photoperiodism, with a long-day response in cell reproduction. The underlying clock is a circadian rhythm with photoinductive capability, peaking at subjective dusk and occurring at the 26th hour in continuous darkness (DD) when transferred from continuous light (LL); it regulates photoinduction, a high-irradiance response (HIR), of a dark-capability of progressing through cell division. We derived the action spectra by irradiating E. gracilis with monochromatic light for 3h at around the 26th hour; the action maxima occurred at 380, 450-460, 480, 610, 640, 660, 680, and 740nm. Except for the maximum at 450-460nm, which was always a major maximum, the maxima greatly depended on the red (R)/far-red (FR) ratio of the prior LL. The high R/FR ratio resulted in a dominant major peak at 640nm and minor peaks at 480 and 680nm, whereas the low ratio resulted in dominant major peaks at 610 and 740nm and minor peaks at 380 and 660nm; the critical fluence was minimally about 60mmolm(-2). These HIRs resulted from the accumulation of corresponding low-fluence responses (LFRs) because we found that repetition of a 3-min light/dark cycle, with critical fluences of 1mmolm(-2), lasting for 3h resulted in the same photoinduction as the continuous 3-h irradiation. Moreover, these LFRs expressed photoreversibility. Thus, photoperiodic photoinduction involves Euglena-phytochrome (640 and 740nm) and blue photoreceptor (460nm). Although 380, 480, 610, 660, and 680nm may also represent Euglena-phytochrome, a definite conclusion awaits further study.

  4. The thyrotropin-releasing hormone secretory system in the hypothalamus of the Siberian hamster in long and short photoperiods.

    Science.gov (United States)

    Ebling, F J P; Wilson, D; Wood, J; Hughes, D; Mercer, J G; Morgan, P J; Barrett, P

    2008-05-01

    Thyrotropin-releasing hormone (TRH) is not only essential for the regulation of the pituitary-thyroid axis, but also exerts complementary effects on energy metabolism within the brain. We hypothesised that increased activity of the TRH secretory system may contribute to seasonal adaptations in the Siberian hamster whereby food intake is decreased in winter, and catabolism of fat stores is increased to support thermogenesis. We determined the distribution of TRH producing neurones and TRH-R1 receptor expressing cells in the hypothalamus, and investigated whether photoperiod regulated this system. TRH-immunoreactive (ir) cell somata and preproTRH mRNA expression were found to be widely distributed throughout the medial hypothalamus, with particular clusters in the paraventricular nucleus, the medial preoptic area and periventricular nucleus, and in the dorsomedial hypothalamus extending into the lateral hypothalamic area. A partial sequence encoding TRH-R1 was cloned from hamster hypothalamic cDNA and used to generate a riboprobe for in situ hybridisation studies. TRH-R1 mRNA expressing cells were abundant throughout the hypothalamus, corresponding to the widespread presence of TRH-ir fibres. Photoperiod did not affect the expression of preproTRH mRNA in any region, and the only significant change in TRH-R1 expression was in the dorsomedial posterior arcuate region. This wide distribution of TRH-producing and receptive cells in the hypothalamus is consistent with its hypothesised neuromodulatory roles in the short-term homeostatic control of appetite, thermoregulation and energy expenditure, but the lack of photoperiodic change in TRH mRNA expression does not support the hypothesis that changes in this system underlie long-term seasonal changes in body weight.

  5. Somatostatin Agonist Pasireotide Promotes a Physiological State Resembling Short-Day Acclimation in the Photoperiodic Male Siberian Hamster (Phodopus sungorus).

    Science.gov (United States)

    Dumbell, R A; Scherbarth, F; Diedrich, V; Schmid, H A; Steinlechner, S; Barrett, P

    2015-07-01

    The timing of growth in seasonal mammals is inextricably linked to food availability. This is exemplified in the Siberian hamster (Phodopus sungorus), which uses the annual cycle of photoperiod to optimally programme energy expenditure in anticipation of seasonal fluctuations in food resources. During the autumn, energy expenditure is progressively minimised by physiological adaptations, including a 30% reduction in body mass, comprising a reduction in both fat and lean tissues. However, the mechanistic basis of this adaptation is still unexplained. We hypothesised that growth hormone (GH) was a likely candidate to underpin these reversible changes in body mass. Administration of pasireotide, a long-acting somatostatin receptor agonist developed for the treatment of acromegaly, to male hamsters under a long-day (LD) photoperiod produced a body weight loss. This comprised a reduction in lean and fat mass, including kidneys, testes and brown adipose tissue, typically found in short-day (SD) housed hamsters. Furthermore, when administered to hamsters switched from SD to LD, pasireotide retarded the body weight increase compared to vehicle-treated hamsters. Pasireotide did not alter photoperiod-mediated changes in hypothalamic energy balance gene expression but altered the expression of Srif mRNA expression in the periventricular nucleus and Ghrh mRNA expression in the arcuate nucleus consistent with a reduction in GH feedback and concurrent with reduced serum insulin-like growth factor-1. Conversely, GH treatment of SD hamsters increased body mass, which included increased mass of liver and kidneys. Together, these data indicate a role for the GH axis in the determination of seasonal body mass of the Siberian hamster.

  6. ZCN8 encodes a potential orthologue of Arabidopsis FT florigen that integrates both endogenous and photoperiod flowering signals in maize.

    Science.gov (United States)

    Lazakis, Chloë M; Coneva, Viktoriya; Colasanti, Joseph

    2011-10-01

    Higher plants use multiple perceptive measures to coordinate flowering time with environmental and endogenous cues. Physiological studies show that florigen is a mobile factor that transmits floral inductive signals from the leaf to the shoot apex. Arabidopsis FT protein is widely regarded as the archetype florigen found in diverse plant species, particularly in plants that use inductive photoperiods to flower. Recently, a large family of FT homologues in maize, the Zea CENTRORADIALIS (ZCN) genes, was described, suggesting that maize also contains FT-related proteins that act as a florigen. The product of one member of this large family, ZCN8, has several attributes that make it a good candidate as a maize florigen. Mechanisms underlying the floral transition in maize are less well understood than those of other species, partly because flowering in temperate maize is dependent largely on endogenous signals. The maize indeterminate1 (id1) gene is an important regulator of maize autonomous flowering that acts in leaves to mediate the transmission or production of florigenic signals. This study finds that id1 acts upstream of ZCN8 to control its expression, suggesting a possible new link to flowering in day-neutral maize. Moreover, in teosinte, a tropical progenitor of maize that requires short-day photoperiods to induce flowering, ZCN8 is highly up-regulated in leaves under inductive photoperiods. Finally, vascular-specific expression of ZCN8 in Arabidopsis complements the ft-1 mutation, demonstrating that leaf-specific expression of ZCN8 can induce flowering. These results suggest that ZCN8 may encode a florigen that integrates both endogenous and environmental signals in maize.

  7. Geminivirus-mediated delivery of florigen promotes determinate growth in aerial organs and uncouples flowering from photoperiod in cotton.

    Directory of Open Access Journals (Sweden)

    Roisin C McGarry

    Full Text Available BACKGROUND: Plant architecture and the timing and distribution of reproductive structures are fundamental agronomic traits shaped by patterns of determinate and indeterminate growth. Florigen, encoded by FLOWERING LOCUS T (FT in Arabidopsis and SINGLE FLOWER TRUSS (SFT in tomato, acts as a general growth hormone, advancing determinate growth. Domestication of upland cotton (Gossypium hirsutum converted it from a lanky photoperiodic perennial to a highly inbred, compact day-neutral plant that is managed as an annual row-crop. This dramatic change in plant architecture provides a unique opportunity to analyze the transition from perennial to annual growth. METHODOLOGY/PRINCIPAL FINDINGS: To explore these architectural changes, we addressed the role of day-length upon flowering in an ancestral, perennial accession and in a domesticated variety of cotton. Using a disarmed Cotton leaf crumple virus (CLCrV as a transient expression system, we delivered FT to both cotton accessions. Ectopic expression of FT in ancestral cotton mimicked the effects of day-length, promoting photoperiod-independent flowering, precocious determinate architecture, and lanceolate leaf shape. Domesticated cotton infected with FT demonstrated more synchronized fruiting and enhanced "annualization". Transient expression of FT also facilitated simple crosses between wild photoperiodic and domesticated day-neutral accessions, effectively demonstrating a mechanism to increase genetic diversity among cultivated lines of cotton. Virus was not detected in the F(1 progeny, indicating that crosses made by this approach do not harbor recombinant DNA molecules. CONCLUSIONS: These findings extend our understanding of FT as a general growth hormone that regulates shoot architecture by advancing organ-specific and age-related determinate growth. Judicious manipulation of FT could benefit cotton architecture to improve crop management.

  8. Feeding Your Baby

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    Full Text Available ... sign in | my dashboard | sign out our cause health topics stories & media research & professionals get involved Search ... your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & premature ...

  9. Feeding Your Baby

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    Full Text Available ... bond with her. Breast milk is the best food for your baby during the first year of ... feeding safe. And then get ready for solid foods ! In This Topic Breastfeeding help Breastfeeding is best ...

  10. Feeding Your Baby

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    Full Text Available ... for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & premature birth The newborn intensive care unit (NICU) Birth defects & other health conditions Loss & ...

  11. Feeding Your Baby

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    Full Text Available ... discomforts when breastfeeding Starting your baby on solid foods Using a breast pump Baby Feeding your ... health & safety ') document.write('') } Ask our experts! Have a question? ...

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    Full Text Available ... your baby Feeding your baby E-mail to a friend Please fill in all fields. Please enter ... hear about breakthroughs for babies and families. Ask a question Our health experts can answer questions about ...

  13. Feeding Your Baby

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    Full Text Available ... bottle-feeding safe. And then get ready for solid foods ! In This Topic Breastfeeding help Breastfeeding is ... and discomforts when breastfeeding Starting your baby on solid foods Using a breast pump In This Topic ...

  14. Feeding Your Baby

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    Full Text Available ... for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & ... health research Prematurity research centers For providers NICU Family Support® Prematurity Campaign Collaborative Info for your patients ...

  15. PHOTOPERIODIC HISTORY AFFECTS THE CRITICAL DAYLENGTH OF THE SHORT-DAY PLANT ACROSYMPHYTON-PURPURIFERUM (RHODOPHYTA)

    NARCIS (Netherlands)

    BREEMAN, AM

    The crustose tetrasporophyte of the red alga Acrosymphyton purpuriferum is a qualitative short-day plant in the formation of its tetrasporangia. The critical daylength for the response was determined in plants precultured in various long-day regimes [20:4, 18:6, 16:8 and 14:10 (L:D, h)]. There was a

  16. Breast feeding in IMD.

    Science.gov (United States)

    MacDonald, A; Depondt, E; Evans, S; Daly, A; Hendriksz, C; Chakrapani A, A; Saudubray, J-M

    2006-01-01

    Breast feeding has proven benefits for many infants with inherited metabolic disorders (IMDs) but, with the exception of phenylketonuria, there are few reports in other conditions. A questionnaire, completed by dietitians and clinicians from 27 IMD centres from 15 countries (caring for a total of over 8000 patients with IMDs on diet) identified breast feeding experience in IMD. Successful, demand breast feeding (in combination with an infant amino acid formula free of precursor amino acids) was reported in 17 infants with MSUD, 14 with tyrosinaemia type I, and 5 with homocystinuria. Eighty-nine per cent were still breast fed at 16 weeks. Fewer infants with organic acidaemias were demand breast fed (7 with propionic acidaemia; 6 with methylmalonic acidaemia and 13 with isovaleric acidaemia) (usually preceded by complementary feeds of a protein-free infant formula or infant amino acid formula free of precursor amino acids). Only 12 infants with urea cycle disorders were given demand breast feeds, but this was unsuccessful beyond 8 days in CPS deficiency. Further work is needed in developing guidelines for feeding and for clinical and biochemical monitoring for breast-fed infants with IMDs.

  17. Equilibrium yield curves under regime switching

    OpenAIRE

    García-Verdú, Santiago

    2010-01-01

    This paper studies how inflation as a macroeconomic indicator affects nominal bond prices. I consider an economy with a representative agent with Epstein- Zin preferences. Regime switching affects the state-space capturing inflation and consumption growth. Thus, the agent is concerned about the intertemporal distribution of risk, which is affected by the persistence of the variables and the regimes. Regime switching allows for structural changes in the volatility of unexpected shocks. To the ...

  18. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed....

  19. Thermal regime of Negotinska Krajina

    Directory of Open Access Journals (Sweden)

    Živković Ljiljana

    2005-01-01

    Full Text Available Negotin Krajina geographically belongs to Mezian tablet that means it is widely open to the influences from the East but main air influences come from the West and North-West causes specific thermal characteristics. Meteorological station "Negotin" is the only one respectable station in the Krajina then we analyze results from various periods since 1901. It is important to emphasize that station "Negotin" doesn't have work continuity since the beginning of the century, thus for analyzing certain climate elements we have had to use method of analogy with station "Zaječar". A part of that, observations were not done by the same methodology so there is lack of some important indicators for this first period. To determine air thermo-regime of Negotin Krajina during 20 century, standard periods (1901-1930., 1931-1960. and 1961-1990 for analyzing climate elements suggested by WMO, were compared. Also, periods from 1925. to 1940. and from 1990. to 2000. were added to this analysis (according to data we had.

  20. Effect of photoperiod on the feline adipose transcriptome as assessed by RNA sequencing.

    Science.gov (United States)

    Mori, Akihiro; Kappen, Kelly L; Dilger, Anna C; Swanson, Kelly S

    2014-07-03

    Photoperiod is known to cause physiological changes in seasonal mammals, including changes in body weight, physical activity, reproductive status, and adipose tissue gene expression in several species. The objective of this study was to determine the effects of day length on the adipose transcriptome of cats as assessed by RNA sequencing. Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exposed to either short days (8 hr light:16 hr dark) or long days (16 hr light:8 hr dark). Cats were fed a commercial diet to maintain baseline body weight to avoid weight-related bias. Subcutaneous adipose biopsies were collected at wk 12 of each period for RNA isolation and sequencing. A total of 578 million sequences (28.9 million/sample) were generated by Illumina sequencing. A total of 170 mRNA transcripts were differentially expressed between short day- and long day-housed cats. 89 annotated transcripts were up-regulated by short days, while 24 annotated transcripts were down-regulated by short days. Another 57 un-annotated transcripts were also different between groups. Adipose tissue of short day-housed cats had greater expression of genes involved with cell growth and differentiation (e.g., myostatin; frizzled-related protein), cell development and structure (e.g., cytokeratins), and protein processing and ubiquitination (e.g., kelch-like proteins). In contrast, short day-housed cats had decreased expression of genes involved with immune function (e.g., plasminogen activator inhibitor 1; chemokine (C-C motif) ligand 2; C-C motif chemokine 5; T-cell activators), and altered expression of genes associated with carbohydrate and lipid metabolism. Collectively, these gene expression changes suggest that short day housing may promote adipogenesis, minimize inflammation and oxidative stress, and alter nutrient metabolism in feline adipose tissue, even when fed to maintain body weight

  1. Comparison of the levels of six endogenous gibberellins in roots and shoots of spinach in relation to photoperiod

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, J.D.; Zeevaart, J.A.D.

    1980-10-01

    This communication describes the distribution of gibberellins (GAs) in roots and shoots of spinach in relation to photoperiod. From previous work shoots were known to contain GA/sub 53/, GA/sub 44/, GA/sub 19/, GA/sub 17/, GA/sub 20/, and GA/sub 29/. We now show by combined gas chromatography-mass spectrometry that roots contain gas chromatography-selected ion current monitoring. Neither GA/sub 17/ nor GA/sub 20/ were detected in root extracts. Analysis by the d-5 corn bioassay also showed no effect of photoperiodic treatment on the levels of GA-like substances in root extracts. Both phloem and xylem exudates had patterns of GA-like activity similar to those found in shoots and roots, respectively. Moreover, foliar application of (/sup 3/H)GA/sub 20/ resulted in the transport of label from the shoot to the roots. Over half of the label in the roots represented unmetabolized (/sup 3/H)GA/sub 20/, indicating that part of the GA/sub 20/ in the phloem is transported to the roots. Consequently, if GA/sub 20/ is made in, or transported to the roots, it is rapidly metabolized in that organ. This is a clear indication that regulation of GA metabolism is greatly different in roots and shoots.

  2. Genetic Analysis and Primary Mapping of pms4,a Photoperiod-Sensitive Genic Male Sterility Gene in Rice (Oryza sativa)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To understand the genetic characteristics of a new photoperiod-sensitive genic male sterile line Mian 9S,some reciprocal crosses were made between Mian 9S and six indica rice materials,Yangdao 6,Luhui 602,Shuihui 527,Mianhui 725,Fuhui 838 and Yixiang 1B.Genetic analysis results suggested that the photoperiod-sensitive genic male sterility (PGMS) of Mian 9S was controlled by a single recessive nuclear gene.Thus,the F2 population derived from the cross of Yangdao 6/Mian 9S was used to map the PGMS gene in Mian 9S.By using SSR markers,the PGMS gene of Mian 9S was mapped on one side of the markers,RM6659 and RM1305,on rice chromosome 4,with the genetic distances of 3.0 cM and 3.5 cM,respectively.The gene was a novel PGMS gene and designated tentatively as pros4.In addition,the application of the pros4 gene was discussed.

  3. Flank gland-secreted putative chemosignals pertaining to photoperiod, endocrine states, and sociosexual behavior in golden hamsters

    Directory of Open Access Journals (Sweden)

    Ying-Juan LIU, Da-Wei WANG, Lixing SUN, Jin-Hua ZHANG, Jian-Xu ZHANG

    2010-12-01

    Full Text Available Behavioral studies have shown that flank glands are involved in chemical communication in golden hamsters Mesocricetus auratus but little chemical analysis has been conducted on volatiles arising from these glands. Using gas chromatography-mass spectrometry, we detected compounds from the flank glands of males, only eight of which were also produced in females. Based on these chemical data we performed a number of further experiments. By manipulating light we found that males exposed to short-photoperiods developed smaller flank glands than those exposed to long-photoperiods. Six flank gland volatiles reduced in relative abundance, which possibly coded for reproductive status of males of this seasonally breeding hamster species. Through dyadic encounters, we were able to induce the formation of dominant-subordinate relationships and show that two glandular compounds became high in relative abundance and may function as dominance pheromones. Castration eliminated all male-specific compounds resulting from flank glands, but bilateral ovariectomies only affected one compound in females. Once these ovariectomized females were treated with testosterone, their glandular compounds resembled those of males, suggesting these compounds are under the main control of androgen. Two female putative pheromones, tetradecanoic acid and hexadecanoic acid, were used in binary choice tests and were both found to attract males over females. Applying a solution of these pheromone compounds to adult males also suppressed their agonistic behavior [Current Zoology 56 (6: 800–812, 2010].

  4. Dependence of nighttime sleep duration in one-month-old infants on alterations in natural and artificial photoperiod

    Science.gov (United States)

    Iwata, Sachiko; Fujita, Fumie; Kinoshita, Masahiro; Unno, Mitsuaki; Horinouchi, Takashi; Morokuma, Seiichi; Iwata, Osuke

    2017-01-01

    Human sleep–wake cycles are entrained by both natural and artificial light–dark cycles. However, little is known regarding when and how the photoperiod changes entrain the biological clock after conception. To investigate the dependence of sleep patterns in young infants on the natural and artificial light–dark cycles, 1,302 pairs of one-month-old infants and their mothers were asked to answer a questionnaire. Birth in spring, longer daytime sleep duration, early/regular light-off times, and longer maternal nighttime sleep duration were identified as independent variables for longer infant nighttime sleep duration in both univariate and multivariate analyses. Longer maternal nighttime sleep duration was dependent on shorter naps and early/regular bed times but not on the season. We found that nighttime sleep duration depended on both natural and artificial diurnal photoperiod changes in one-month-old infants. Although sleep patterns of infants mimicked those of their mothers, nighttime sleep duration depended on the season, and was positively associated with daytime sleep duration, only in the infants. These specific variables, which render sleep patterns of the infants different from those of their mothers, might be a clue to reveal the covert acquisition process of mature circadian rhythms after birth. PMID:28303945

  5. CmFTL2 is involved in the photoperiod- and sucrose-mediated control of flowering time in chrysanthemum.

    Science.gov (United States)

    Sun, Jing; Wang, Heng; Ren, Liping; Chen, Sumei; Chen, Fadi; Jiang, Jiafu

    2017-01-01

    The chrysanthemum genome harbors three FT-like genes: CmFTL1 and CmFTL3 are thought to act as regulators of floral induction under long-day (LD) and short-day (SD) conditions, respectively, whereas the function of CmFTL2 is currently unclear. The objective of the present research was to explore the function of CmFTL2 in the determination of flowering time of the photo-insensitive chrysanthemum cultivar 'Floral Yuuka', both in response to variation in the photoperiod and to the exogenous provision of sucrose. Spraying leaves of 'Floral Yuuka' plants with 50 mM sucrose accelerated flowering and increased the level of CmFTL2 transcription in the leaf more strongly than either CmFTL1 or FTL3 under both long and SD conditions. Transcription profiling indicated that all three CmFTL genes were upregulated during floral induction. The relationship of the CmFTL2 sequence with that of other members of the PEBP family suggested that its product contributes to the florigen rather than to the anti-florigen complex. The heterologous expression of CmFTL2 in the Arabidopsis thaliana ft-10 mutant rescued the mutant phenotype, showing that CmFTL2 could compensate for the absence of FT. These results suggest that CmFTL2 acts as a regulator of floral transition and responds to both the photoperiod and sucrose.

  6. Three FLOWERING LOCUS T-like genes function as potential florigens and mediate photoperiod response in sorghum.

    Science.gov (United States)

    Wolabu, Tezera W; Zhang, Fei; Niu, Lifang; Kalve, Shweta; Bhatnagar-Mathur, Pooja; Muszynski, Michael G; Tadege, Million

    2016-05-01

    Sorghum is a typical short-day (SD) plant and its use in grain or biomass production in temperate regions depends on its flowering time control, but the underlying molecular mechanism of floral transition in sorghum is poorly understood. Here we characterized sorghum FLOWERING LOCUS T (SbFT) genes to establish a molecular road map for mechanistic understanding. Out of 19 PEBP genes, SbFT1, SbFT8 and SbFT10 were identified as potential candidates for encoding florigens using multiple approaches. Phylogenetic analysis revealed that SbFT1 clusters with the rice Hd3a subclade, while SbFT8 and SbFT10 cluster with the maize ZCN8 subclade. These three genes are expressed in the leaf at the floral transition initiation stage, expressed early in grain sorghum genotypes but late in sweet and forage sorghum genotypes, induced by SD treatment in photoperiod-sensitive genotypes, cooperatively repressed by the classical sorghum maturity loci, interact with sorghum 14-3-3 proteins and activate flowering in transgenic Arabidopsis plants, suggesting florigenic potential in sorghum. SD induction of these three genes in sensitive genotypes is fully reversed by 1 wk of long-day treatment, and yet, some aspects of the SD treatment may still make a small contribution to flowering in long days, indicating a complex photoperiod response mediated by SbFT genes.

  7. Photoperiodic control of sugar release during the floral transition: What is the role of sugars in the florigenic signal?

    Science.gov (United States)

    Ortiz-Marchena, M Isabel; Romero, José M; Valverde, Federico

    2015-01-01

    Florigen is a mobile signal released by the leaves that reaching the shoot apical meristem (SAM), changes its developmental program from vegetative to reproductive. The protein FLOWERING LOCUS T (FT) constitutes an important element of the florigen, but other components such as sugars, have been also proposed to be part of this signal. (1-5) We have studied the accumulation and composition of starch during the floral transition in Arabidopsis thaliana in order to understand the role of carbon mobilization in this process. In A. thaliana and Antirrhinum majus the gene coding for the Granule-Bound Starch Synthase (GBSS) is regulated by the circadian clock (6,7) while in the green alga Chlamydomonas reinhardtii the homolog gene CrGBSS is controlled by photoperiod and circadian signals. (8,9) In a recent paper(10) we described the role of the central photoperiodic factor CONSTANS (CO) in the regulation of GBSS expression in Arabidopsis. This regulation is in the basis of the change in the balance between starch and free sugars observed during the floral transition. We propose that this regulation may contribute to the florigenic signal and to the increase in sugar transport required during the flowering process.

  8. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  9. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  10. Enteral feeding without pancreatic stimulation

    DEFF Research Database (Denmark)

    Kaushik, Neeraj; Pietraszewski, Marie; Holst, Jens Juul

    2005-01-01

    OBJECTIVE: All forms of commonly practiced enteral feeding techniques stimulate pancreatic secretion, and only intravenous feeding avoids it. In this study, we explored the possibility of more distal enteral infusions of tube feeds to see whether activation of the ileal brake mechanism can result...... in enteral feeding without pancreatic stimulation, with particular reference to trypsin, because the avoidance of trypsin stimulation may optimize enteral feeding in acute pancreatitis. METHODS: The pancreatic secretory responses to feeding were studied in 36 healthy volunteers by standard double......-lumen duodenal perfusion/aspiration techniques over 6 hours. Subjects were assigned to no feeding (n = 7), duodenal feeding with a polymeric diet (n = 7) or low-fat elemental diet (n = 6), mid-distal jejunal feeding (n = 11), or intravenous feeding (n = 5). All diets provided 40 kcal/kg ideal body weight/d and 1...

  11. Crustal stress regime in Italy

    Directory of Open Access Journals (Sweden)

    M. Cesaro

    1997-06-01

    Full Text Available In order to obtain a reliable map of the present-day stress field in Italy, needed to better understand the active tectonic processes and to contribute to the assessment of seismic hazard, in 1992 we started to collect and analyze new data from borehole breakouts in deep oil and geothermal wells and focal mechanisms of earthquakes (2.5 < M <5 occurred in Italy between 1988 and 1995. From about 200 deep wells and 300 focal mechanisms analyzed to date, we infer that: the internal (SW sector of the Northern Apenninic arc is extending with minimum compressional stress (Shmin oriented ? ENE, while the external front is thrusting over the Adriatic foreland (Shmin ? NW-SE. The entire Southern Apennine is extending in NE direction (from the Tyrrhenian margin to the Apulian foreland and compression (in the foredeep is no longer active at the outer (NE thrust front. Between these two arcs, an abrupt change in the tectonic regime is detected with directions of horizontal stress changing by as much as 90º in the external front, around latitude 430N. Along the Ionian side of the Calabrian arc the stress directions inferred from breakouts and focal mechanisms are scattered with a hint of rotation from N-S Shmin close to the Southern Apennines, to ~ E-W directions in the Messina Strait. In Sicily, a NW-SE direction of SHmax is evident in the Hyblean foreland, parallel to the direction of plate motion between Africa and Europe. A more complex pattern of stress directions is observed in the thrust belt zone, with rotations from the regional trend (NW í directed SHmax to NE oriented SHmax. A predominant NW direction of SHmax is also detected in mainland Sicily from earthquake focal mechanisms, but no well data are available in this region. In the northern part of Sicily (Aeolian Islands a ~N-S direction of SHmax is observed.

  12. Framing of regimes and transition strategies

    DEFF Research Database (Denmark)

    Jensen, Jens Stissing

    2012-01-01

    This article suggests that transition strategies are always formulated in the context of specific representations of the regime and the challenges it faces. It is argued that the framing of a regime affects the envisioning of transition strategies. An analysis of the current development agenda...

  13. Multiscale regime shifts and planetary boundaries

    NARCIS (Netherlands)

    Hughes, T.P.; Carpenter, S.; Rockstrom, J.; Scheffer, M.; Walker, B.

    2013-01-01

    Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a ti

  14. LEGAL MATRIMONIAL REGIME IN B&H

    Directory of Open Access Journals (Sweden)

    Boris Krešić

    2011-12-01

    Full Text Available Matrimonial regime between spouses or between extramarital partners, and between parents and children is regulated by the Family Law Act of Bosnia and Herzegovina Federation, hereinafter FLA B&HF (SG FBiH 35/05, 41/05, Family Law Act of the Republic of Srpska, hereinafter FLA RS (SG RS”54/02, 41/08 and the Family Law Act of Brčko District, hereinafter FLA BD (SG RS, 66/07. Legal rules used for the regulation of the matrimonial regime between spouses, as well as between spouses and third parties make matrimonial regime (Ponjavić, 2005, p. 361. Matrimonial regime between spouses in family legislation in Bosnia and Herzegovina (B&H is regulated in two following ways: as legal matrimonial regime and as contract matrimonial regime. Legal regime is the one which applies on spouses if not arranged otherwise prior to contracting marriage or during marriage. In this paper the author indicates the differences between the legal matrimonial regimes of the two entities as well as those between the entities and Brčko District of Bosnia and Herzegovina.

  15. LOW DOSE MAGNESIUM SULPHATE REGIME FOR ECLAMPSIA

    Directory of Open Access Journals (Sweden)

    Bangal V

    2009-09-01

    Full Text Available Pre- eclampsia is one of the commonest medical complications seen during pregnancy. It contributes significantly to maternal and perinatal morbidity and mortality. Dr.J.A.Pritchard in 1955, introduced magnesium sulphate for control of convulsions in eclampsia and is used worldwide. Considering the low body mass index of indian women, a low dose magnesium sulphate regime has been introduced by some authors. Present study was carried out at tertiary care centre in rural area. Fifty cases of eclampsia were randomly selected to find out the efficacy of low dose magnesium sulphate regime to control eclamptic convulsions. Maternal and perinatal outcome and magnesium toxicity were analyzed. It was observed that 86% cases responded to initial intravenous dose of 4 grams of 20% magnesium sulphate . Eight percent cases, who got recurrence of convulsion, were controlled by additional 2 grams of 20% magnesium sulphate. Six percent cases required shifting to standard Pritchard regime, as they did not respond to low dose magnesium sulphate regime. The average total dose of magnesium sulphate required for control of convulsions was 20 grams ie. 54.4% less than that of standard Pritchard regime. The maternal and perinatal morbidity and mortality in the present study werecomparable to those of standard Pritchard regime. The study did not find a single case of magnesium related toxicity with low dose magnesium sulphate regime. Low dose magnesium sulphate regime was found to be safe and effective in eclampsia.

  16. Flotation of high-grade fluorite in a short column under negative bias regime

    OpenAIRE

    2006-01-01

    RESTRITO This paper presents flotation results carried out on fluorite ore using a relatively short column, operated under negative bias regime and without wash water. The term short column is used from a kinetic point of view from which collection zone comes out to be around 8 m tall (the relation height/diameter appears valid for industrial size columns). Negative bias was achieved making tailing flow smaller than feed flow. Hence, part of the water is carried up within bubbles wakes. No...

  17. HvLUX1 is a candidate gene underlying the early maturity 10 locus in barley: phylogeny, diversity, and interactions with the circadian clock and photoperiodic pathways.

    Science.gov (United States)

    Campoli, Chiara; Pankin, Artem; Drosse, Benedikt; Casao, Cristina M; Davis, Seth J; von Korff, Maria

    2013-09-01

    Photoperiodic flowering is a major factor determining crop performance and is controlled by interactions between environmental signals and the circadian clock. We proposed Hvlux1, an ortholog of the Arabidopsis circadian gene LUX ARRHYTHMO, as a candidate underlying the early maturity 10 (eam10) locus in barley (Hordeum vulgare L.). The link between eam10 and Hvlux1 was discovered using high-throughput sequencing of enriched libraries and segregation analysis. We conducted functional, phylogenetic, and diversity studies of eam10 and HvLUX1 to understand the genetic control of photoperiod response in barley and to characterize the evolution of LUX-like genes within barley and across monocots and eudicots. We demonstrate that eam10 causes circadian defects and interacts with the photoperiod response gene Ppd-H1 to accelerate flowering under long and short days. The results of phylogenetic and diversity analyses indicate that HvLUX1 was under purifying selection, duplicated at the base of the grass clade, and diverged independently of LUX-like genes in other plant lineages. Taken together, these findings contribute to improved understanding of the barley circadian clock, its interaction with the photoperiod pathway, and evolution of circadian systems in barley and across monocots and eudicots.

  18. Photoperiodic regulation of cellular retinol binding protein, CRBP1 [corrected] and nestin in tanycytes of the third ventricle ependymal layer of the Siberian hamster.

    Science.gov (United States)

    Barrett, Perry; Ivanova, Elena; Graham, E Scott; Ross, Alexander W; Wilson, Dana; Plé, Helene; Mercer, Julian G; Ebling, Francis J; Schuhler, Sandrine; Dupré, Sandrine M; Loudon, Andrew; Morgan, Peter J

    2006-12-01

    Tanycytes in the ependymal layer of the third ventricle act both as a barrier and a communication gateway between the cerebrospinal fluid, brain and portal blood supply to the pituitary gland. However, the range, importance and mechanisms involved in the function of tanycytes remain to be explored. In this study, we have utilized a photoperiodic animal to examine the expression of three unrelated gene sequences in relation to photoperiod-induced changes in seasonal physiology and behaviour. We demonstrate that cellular retinol binding protein [corrected] (CRBP1), a retinoic acid transport protein, GPR50, an orphan G-protein-coupled receptor and nestin, an intermediate filament protein, are down-regulated in short-day photoperiods. The distribution of the three sequences is very similar, with expression located in cells with tanycyte morphology in the region of the ependymal layer where tanycytes are located. Furthermore, CRBP1 expression in the ependymal layer is shown to be independent of a circadian clock and altered testosterone levels associated with testicular regression in short photo-period. Pinealectomy of Siberian hamsters demonstrates CRBP1 expression is likely to be dependent on melatonin output from the pineal gland. This provides evidence that tanycytes are seasonally responsive cells and are likely to be an important part of the mechanism to facilitate seasonal physiology and behaviour in the Siberian hamster.

  19. Photoperiodic induced melatonin regulates immunity and expression pattern of melatonin receptor MT1 in spleen and bone marrow mononuclear cells of male golden hamster.

    Science.gov (United States)

    Vishwas, Dipanshu Kumar; Haldar, Chandana

    2013-11-05

    The pineal gland transduces day length information into chemical signal of melatonin that ultimately translates photic stimulus into season-specific immune responses to promote survival of individual from incidence of opportunistic diseases. To date, the immune adjustments being a result of photoperiodic exposures for any nocturnal seasonally breeding rodent have not been systematically examined. Therefore, we evaluated the humoral and cell mediated immune responses of photoperiodically entrained male golden hamsters. Short day induced melatonin increased the immune parameters such as spleen mass, total leukocyte (TLC) and lymphocyte count (LC), proliferation of splenocytes, peripheral blood mononuclear cells (PBMCs) and bone marrow mononuclear cells (BMMNCs) along with serum IL-2 and anti-Keyhole Limpet Hemocyanin (KLH) IgG production when compared with long day experienced hamsters. Short term melatonin treatment (for two weeks) to long day hamsters enhanced to some extent the proliferation of splenocytes, PBMC and TLC/LC. We also localized the melatonin membrane receptor MT1 in spleen and BMMNCs that strongly supported our western blot analysis for the expression of MT1 in spleen suggesting that different photoperiodically induced circulatory melatonin is responsible for the immunomodulation. Therefore, photoperiod can influence the peripheral melatonin level to improve immune responses of hamsters according to season for better survival.

  20. Representing infant feeding: content analysis of British media portrayals of bottle feeding and breast feeding

    OpenAIRE

    Henderson, L.; KITZINGER, Jenny; Green, J.

    2001-01-01

    Objective: To examine how breast feeding and bottle feeding are represented by the British media.\\ud Design: Content analysis.\\ud Subjects: Television programmes and newspaper articles that made reference to infant feeding during March 1999.\\ud Setting: UK mass media.\\ud Main outcome measures: Visual and verbal references to breast or bottle feeding in newspapers and television programmes.\\ud Results: Overall, 235 references to infant feeding were identified in the television sample and 38 in...

  1. Photoperiod-independent changes in immunoreactive brain gonadotropin-releasing hormone (GnRH) in a free-living, tropical bird.

    Science.gov (United States)

    Moore, Ignacio T; Bentley, George E; Wotus, Cheryl; Wingfield, John C

    2006-01-01

    Timing of seasonal reproduction in high latitude vertebrates is generally regulated by photoperiodic cues. Increasing day length in the spring is associated with changes in the brain that are responsible for mediating reproductive activities. A primary example of this is the increased content of gonadotropin-releasing hormone (GnRH) in the preoptic area of the hypothalamus in birds as they enter the spring breeding season. Increased GnRH activity stimulates the release of luteinizing hormone and follicle-stimulating hormone from the anterior pituitary. These gonadotropins induce growth of the gonads and release of sex steroids which act on the brain to mediate reproductive behaviors. By contrast, seasonal breeding in the tropics can occur in the absence of significant changes in photoperiod. To our knowledge, no studies have investigated whether seasonal breeding in free-living tropical vertebrates is associated with seasonal changes in the GnRH system. We studied two populations of rufous-collared sparrows (Zonotrichia capensis) at the equator, separated by only 25 km, but with asynchronous reproductive phenologies associated with local climate and independent of photoperiodic cues. We collected brains and measured GnRH immunoreactivity (GnRH-ir) during each population's breeding and non-breeding periods. Breeding males had larger, but not more, GnRH-ir cells than non-breeding birds. The plasticity of the GnRH system was associated with local climate, such that the two populations exhibited asynchronous changes in GnRH-ir despite experiencing identical photoperiod conditions. Our results demonstrate that tropical birds can exhibit neural changes similar to those exhibited in higher latitude birds. However, these tropical populations appear to be using supplementary cues (e.g., rainfall, temperature, food availability) in a similar way to higher latitude species using an initial predictive cue (photoperiod). These results raise questions about the evolution of

  2. Low Emission Feed

    NARCIS (Netherlands)

    Klop, G.

    2016-01-01

    Research into manipulating methane (CH4) production as a result of enteric fermentation in ruminants currently receives global interest. Using feed additives may be a feasible strategy to mitigate CH4 as they are supplied in such amounts that the basal diet composition will not be largely affected.

  3. Feed sources for livestock

    NARCIS (Netherlands)

    Zanten, van H.H.E.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Cu

  4. Low Emission Feed

    NARCIS (Netherlands)

    Klop, G.

    2016-01-01

    Research into manipulating methane (CH4) production as a result of enteric fermentation in ruminants currently receives global interest. Using feed additives may be a feasible strategy to mitigate CH4 as they are supplied in such amounts that the basal diet composition will not be largely affected.

  5. Feed sources for livestock

    NARCIS (Netherlands)

    Zanten, van H.H.E.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way.

  6. [History of complementary feeding].

    Science.gov (United States)

    Turck, D

    2010-12-01

    Complementary feeding, which embraces all solid and liquid foods other than breast milk or infant formula, is strongly influenced by cultural, familial and economic factors. For many times, there was a strong taboo on the use of colostrum ("the white blood") during the first week after delivery, sometimes even the first month. Therefore, the newborn baby received complementary foods as gruel, or panada. However, in the Greek civilization, wet nurses were asked by contract to breastfeed exclusively for the first 6 months and to start complementary feeding thereafter. From the sixteenth century onwards, many writers deplored the practice of giving gruel and panada during the first six months before the teeth erupted. In 1921, a Swedish pediatrician, Jundell, reported for the first time that starting complementary feeding at 6 months of age was associated with a better growth and resistance to infections. The recommendation of the World Health Organization to start complementary feeding after a 6-month period of exclusive breastfeeding is often in contradiction with the habits of the populations to propose very early other food sources than breast milk. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  7. Feeding of Diarmis Proboscis

    Science.gov (United States)

    Young, Jocelyn

    2005-01-01

    The feeding of Diarmis proboscis is an exciting outdoor laboratory activity that demonstrates a single concept of adaptations--cryptic colorations. The students are "transformed" into D. proboscis (no Harry Potter magic needed) in order to learn how adaptations work in the natural world. Prior to beginning this activity, students should have a…

  8. Feed sources for livestock

    NARCIS (Netherlands)

    Zanten, van H.H.E.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Cu

  9. Feeding Your Baby

    Medline Plus

    Full Text Available ... healthy Problems and discomforts when breastfeeding Starting your baby on solid foods Using a breast pump In This Topic Breastfeeding ... healthy Problems and discomforts when breastfeeding Starting your baby on solid foods Using a breast pump Baby Feeding your baby ...

  10. 雨生红球藻的光周期效应%Effect of Photoperiod on Microalgae Haematococcus pluvialis

    Institute of Scientific and Technical Information of China (English)

    韦韬; 顾文辉; 李健; 张波; 潘光华; 朱大玲; 王广策

    2013-01-01

    Haematococcus pluvialis is a green microalga with the largest astaxanthin content among all the potential organism sources in the world. Astaxanthin is a red ketocarotenoid with high antioxidant ability and has been widely used in aquaculture, nutraceutical, cosmetic and food industries. Illumination is an essential factor for the photosynthesis of algae. As well, light intensity and photoperiod greatly affect the growth and astaxanthin accumulation of H. pluvialis. In this work, we studied the effect of photoperiod on the growth and astaxanthin accumulation of H. pluvialis under different light intensities (70, 120 and 300 μmol·m-2-s-1) by analyzing cell morphologic features, growth rate and astaxanthin content under different conditions. The suitable photoperiod was 16/8 h, with maximal growth 0.43 d-1 obtained at 120 μmol·m-2s-1. The astaxanthin content within a single cell increased with the light intensity and illumination time increases. After 15 days, the alga cell turned bright red under continuous illumination at 300 μmol·m-2s-1, with average diameter 21.02 μm. The highest astaxanthin content was 39.40 pg·cell-1.%雨生红球藻(Haematococcus pluvialis)是一种单细胞淡水绿藻,是自然界已知的中虾青素含量最高的生物物种.通过分析3种光照强度(70、120和300 μmol·m-2.s-1)下雨生红球藻细胞形态、生长速率和虾青素含量的差异,对其光周期效应进行了研究.结果表明,不同光强下适宜雨生红球藻生长的光周期均为16小时光照/8小时黑暗,光强为120 μmol·m-2·s-1时其细胞生长速率最大,为0.43 d-1;细胞内虾青素含量随着光强和光照时间的增加而增加,在300 μmol·m-2.S-1光强下连续光照15天后,藻细胞呈亮红色,平均直径为21.02 μm,最大虾青素值达39.40 pg·cell-1.

  11. Genetic analyses for deciphering the status and role of photoperiodic and maturity genes in major Indian soybean cultivars

    Indian Academy of Sciences (India)

    SANJAY GUPTA; VIRENDER SINGH BHATIA; GIRIRAJ KUMAWAT; DEVSHREE THAKUR; GOURAV SINGH; RACHANA TRIPATHI; GYANESH SATPUTE; RAMGOPAL DEVADAS; SAYED MASROOR HUSAIN; SURESH CHAND

    2017-03-01

    Allelic combinations of major photoperiodic (E1, E3, E4) and maturity (E2) genes have extended the adaptation of quantitative photoperiod sensitive soybean crop from its origin (China ∼35◦N latitude) to both north (up to ∼50◦N) and south (up to 40◦S) latitudes, but their allelic status and role in India (6–35◦N) are unknown. Loss of function and hypoactive alleles of these genes are known to confer photoinsensitivity to long days and early maturity. Early maturity has helped to adapt soybean to short growing season of India. We had earlier found that all the Indian cultivars are sensitive to incandescent long day (ILD) and could identify six insensitive accessions through screening 2071 accessions under ILD. Available models for ILD insensitivity suggested that identified insensitive genotypes should be either e3/e4 or e1 (e1-nl or e1-fs) with either e3 or e4. We foundthat one of the insensitive accessions (EC 390977) was of e3/e4 genotype and hybridized it with four ILD sensitive cultivars JS 335, JS 95-60, JS 93-05, NRC 37 and an accession EC 538828. Inheritance studies and marker-based cosegregation analyses confirmed the segregation of E3 and E4 genes and identified JS 93-05 and NRC 37 as E3E3E4E4 and EC 538828 ase3e3E4E4. Further, genotyping through sequencing, derived cleaved amplified polymorphic sequences (dCAPS) and cleaved amplified polymorphic sequences (CAPS) markers identified JS 95-60 with hypoactive e1-as and JS 335 with loss of function e3-fs alleles. Presence of photoperiodic recessive alleles in these two most popular Indian cultivars suggested for their role in conferring early flowering and maturity. This observation could be confirmed in F2 population derived from the cross JS 95-60 × EC 390977, where individuals with e1-as e1-as and e4e4 genotypes could flower 7 and 2.4 days earlier, respectively. Possibility of identification of new alleles or mechanism for ILD insensitivity and use of photoinsensitivity in Indian conditions

  12. Allelic variation at the vernalization and photoperiod sensitivity loci in Chinese winter wheat cultivars (Triticum aestivum L.

    Directory of Open Access Journals (Sweden)

    Xiangfen eZhang

    2015-07-01

    Full Text Available A total of 205 wheat cultivars from the Yellow and Huai valley of China were used to identify allelic variations of vernalization and photoperiod response genes, as well as the copy number variations (CNVs of Ppd-B1 and Vrn-A1 genes. A novel Vrn-D1 allele with 174-bp insertion in the promoter region of the recessive allele vrn-D1 was discovered in three Chinese wheat cultivars and designated as Vrn-D1c. Quantitative real-time polymerase chain reaction showed that cultivars with the Vrn-D1c allele exhibited significantly higher expression of the Vrn-D1 gene than that in cultivars with the recessive allele vrn-D1, indicating that the 174-bp insertion of Vrn-D1c contributed to the increase in Vrn-D1 gene expression and caused early heading and flowering. The five new cis-elements (Box II-like, 3-AF1 binding site, TC-rich repeats, Box-W1 and CAT-box in the 174-bp insertion possibly promoted the basal activity level of Vrn-D1 gene. Two new polymorphism combinations of photoperiod genes were identified and designated as Ppd-D1_Hapl-IX and Ppd-D1_Hapl-X. Association of the CNV of Ppd-B1 gene with the heading and flowering days showed that the cultivars with Ppd-B1_Hapl-VI demonstrated the earliest heading and flowering times, and those with Ppd-B1_Hapl-IV presented the latest heading and flowering times in three cropping seasons. Distribution of the vernalization and photoperiod response genes indicated that all recessive alleles at the four vernalization response loci, Ppd-B1_Hapl-I at Ppd-B1 locus, and Ppd-D1_Hapl-I at the Ppd-D1 locus were predominant in Chinese winter wheat cultivars. This study can provide useful information for wheat breeding programs to screen wheat cultivars with relatively superior adaptability and maturity.

  13. Effects of photoperiod on nutrient removal, biomass production, and algal-bacterial population dynamics in lab-scale photobioreactors treating municipal wastewater.

    Science.gov (United States)

    Lee, Chang Soo; Lee, Sang-Ah; Ko, So-Ra; Oh, Hee-Mock; Ahn, Chi-Yong

    2015-01-01

    Effects of photoperiod were investigated in lab-scale photobioreactors containing algal-bacterial consortia to reduce organic nutrients from municipal wastewater. Under three photoperiod conditions (12 h:12 h, 36 h:12 h, and 60 h:12 h dark–light cycles), nutrient removals and biomass productions were measured along with monitoring microbial population dynamics. After a batch operation for 12 days, 59–80% carbon, 35–88% nitrogen, and 43–89% phosphorus were removed from influents, respectively. In this study, carbon removal was related positively to the length of dark cycles, while nitrogen and phosphorus removals inversely. On the contrast, the highest microbial biomass in terms of chlorophyll a, dry cell weight, and algal/bacterial rRNA gene markers was produced under the 12 h:12 h dark–light cycle among the three photoperiods. The results showed 1) simultaneous growths between algae and bacteria in the microbial consortia and 2) efficient nitrogen and phosphorus removals along with high microbial biomass production under prolonged light conditions. Statistical analyses indicated that carbon removal was significantly related to the ratio of bacteria to algae in the microbial consortia along with prolonged dark conditions (p < 0.05). In addition, the ratio of nitrogen removal to phosphorus removal decreased significantly under prolonged dark conditions (p < 0.001). These results indicated that the photoperiod condition has remarkable impacts on adjusting nutrient removal, producing microbial biomass, and altering algal-bacterial population dynamics. Therefore, the control of photoperiod was suggested as an important operating parameter in the algal wastewater treatment.

  14. Effects of season and artificial photoperiod on semen and seminal plasma characteristics in bucks of two goat breeds maintained in a semen collection center

    Directory of Open Access Journals (Sweden)

    Francisco Arrebola

    2017-05-01

    Full Text Available Aim: This study quantified the effects of season and photoperiodic treatment on semen and seminal plasma (SP characteristics in 12 bucks of two Spanish goat breeds (Murciano-Granadina, and Payoya for the past 1 year. Materials and Methods: A total of 6 bucks (three of each breed were exposed to the natural day length and the other six males (three of each breed were exposed to alternating conditions of 2 months of long days (16 h light and 2 months of short days (8 h light. Weekly concentrations of glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST, lactate dehydrogenase (LDH, potassium, testosterone, and protein in SP were measured. Reaction time and scrotal circumference were recorded, and plasma testosterone concentrations were measured before semen collection. Results: Sperm volume, LDH, and potassium concentration in SP, and reaction time did not differ significantly between breeds, seasons, and photoperiodic treatment. Sperm concentrations were higher (p<0.001 in spring and summer than they were in autumn and winter. Mean percentage of positive hypo-osmotic swelling test sperm was the highest in summer and under the artificial photoperiod (p<0.01. GOT/AST concentrations differed (p<0.01 between breeds and seasons. Breed, season, and photoperiod had significant (p<0.001 effects on protein and testosterone levels in SP. Plasma testosterone concentrations were highest in summer (p<0.001, and differed significantly (p<0.01 between breeds. Scrotal perimeter differed significantly (p<0.001 between breeds and photoperiod. Conclusion: Recognition of those seasonal and breed-specific differences in the performance of bucks should help to improve the management of individual semen samples for use in artificial insemination programs.

  15. Feed intake, growth and feed utilization patterns of pigs highly ...

    African Journals Online (AJOL)

    in genetically lean and obese pigs, and showed that feed intake is ... apportionment of consumed energy towards protein and ..... alia, genetic potential for protein deposition and its ... The content and dietary balance of feed nutrients, such as ...

  16. Prospects of complete feed system in ruminant feeding: A review

    Directory of Open Access Journals (Sweden)

    Yasir Afzal Beigh

    2017-04-01

    Full Text Available Effective utilization of available feed resources is the key for economical livestock rearing. Complete feed system is one of the latest developments to exploit the potential of animal feed resources in the best possible way. The complete feed is a quantitative mixture of all dietary ingredients, blended thoroughly to prevent separation and selection, fed as a sole source of nutrients except water and is formulated in a desired proportion to meet the specific nutrient requirements. The concentrate and roughage levels may vary according to the nutrient requirement of ruminants for different production purposes. The complete feed with the use of fibrous crop residue is a noble way to increase the voluntary feed intake and thus animal's production performance. In this system of feeding, the ruminant animals have continuous free choice availability of uniform feed mixture, resulting in more uniform load on the rumen and less fluctuation in release of ammonia which supports more efficient utilization of ruminal non-protein nitrogen. Feeding complete diet stabilizes ruminal fermentation, thereby improves nutrient utilization. This feeding system allows expanded use of agro-industrial byproducts, crop residues and nonconventional feeds in ruminant ration for maximizing production and minimizing feeding cost, thus being increasingly appreciated. However, to extend the concept extensively to the field and make this technology successful and viable for farmers, more efforts are needed to be taken.

  17. Prospects of complete feed system in ruminant feeding: A review

    Science.gov (United States)

    Beigh, Yasir Afzal; Ganai, Abdul Majeed; Ahmad, Haidar Ali

    2017-01-01

    Effective utilization of available feed resources is the key for economical livestock rearing. Complete feed system is one of the latest developments to exploit the potential of animal feed resources in the best possible way. The complete feed is a quantitative mixture of all dietary ingredients, blended thoroughly to prevent separation and selection, fed as a sole source of nutrients except water and is formulated in a desired proportion to meet the specific nutrient requirements. The concentrate and roughage levels may vary according to the nutrient requirement of ruminants for different production purposes. The complete feed with the use of fibrous crop residue is a noble way to increase the voluntary feed intake and thus animal’s production performance. In this system of feeding, the ruminant animals have continuous free choice availability of uniform feed mixture, resulting in more uniform load on the rumen and less fluctuation in release of ammonia which supports more efficient utilization of ruminal non-protein nitrogen. Feeding complete diet stabilizes ruminal fermentation, thereby improves nutrient utilization. This feeding system allows expanded use of agro-industrial by­products, crop residues and nonconventional feeds in ruminant ration for maximizing production and minimizing feeding cost, thus being increasingly appreciated. However, to extend the concept extensively to the field and make this technology successful and viable for farmers, more efforts are needed to be taken. PMID:28507415

  18. Photoperiodic Co-Regulation of Kisspeptin, Neurokinin B and Dynorphin in the Hypothalamus of a Seasonal Rodent

    DEFF Research Database (Denmark)

    Bartzen-Sprauer, J; Klosen, P; Ciofi, P;

    2014-01-01

    In many species, sexual activity varies on a seasonal basis. Kisspeptin (Kp), a hypothalamic neuropeptide acting as a strong activator of gonadotrophin-releasing hormone neurones, plays a critical role in this adaptive process. Recent studies report that two other neuropeptides, namely neurokinin B......-dependent in a seasonal rodent, the Syrian hamster, which exhibits robust seasonal rhythms in reproductive activity. The majority of Kp neurones in the arcuate nucleus co-express NKB and DYN and the expression of all three peptides is decreased under a short (compared to long) photoperiod, leading to a 60% decrease...... in the number of KNDy neurones under photo-inhibitory conditions. In seasonal rodents, RFamide-related peptide (RFRP) neurones of the dorsomedial hypothalamus are also critical for seasonal reproduction. Interestingly, NKB and DYN are also expressed in the dorsomedial hypothalamus but do not co...

  19. pms3 is the locus causing the original photoperiod-sensitive male sterility mutation of‘Nongken 58S’

    Institute of Scientific and Technical Information of China (English)

    梅明华; 陈亮; 章志宏; 李子银; 徐才国; 张启发

    1999-01-01

    Photoperiod-sensitive genic male sterile (PSGMS) rice is a very useful germplasm for hybrid rice development. It was first found as a spontaneous mutant in a japonica cultivar ’Nongken 58’. pms3 on chromosome 12 was determined to be the locus where the original PSGMS mutation occurred, changing the normal cultivar Nongken 58 to PSGMS Nongken 58S. Large amounts of RAPD and AFLP analyses were also conducted for the fine mapping of the pms3 genomic region, which resulted in 4 molecular markers linked to pms3. Although these markers somewhat increased the marker density of this region, the pms3 locus is still located in a marker-sparse region.

  20. Isolation and Analysis of the Promoter of OsRacD from Photoperiod Sensitive Genic Male Sterile Rice

    Institute of Scientific and Technical Information of China (English)

    LIANG Wei-hong; WU Nai-hu

    2006-01-01

    By using OsRacD cDNA as probe to screen the genomic library of photoperiod sensitive genic male sterile rice line Nongken 58S, a positive clone containing 2 kb promoter and 396 bp coding region of OsRacD was obtained. Compared with the promoter of OsRacD cloned by reverse PCR from normal rice variety Nongken 58 (Nongken 58N), the homology was 99.8%, and the different nucleotides were outside the predicted response elements in promoter, suggesting that the fertility between rice varieties Nongken 58S and Nongken 58N under the long-day conditions was not attributed to the difference in the structure of OsRacD upstream regulation sequences, but to the developmental regulation of gene differential expression.

  1. Effect of feed presentation on feeding patterns of dairy calves.

    Science.gov (United States)

    Miller-Cushon, E K; Bergeron, R; Leslie, K E; Mason, G J; DeVries, T J

    2013-01-01

    The objectives of this study were to determine the effect of feed presentation on meal frequency and duration, as well as diurnal feeding patterns of dairy calves, and to assess any longer-term differences in feeding patterns resulting from previous experience. Twenty Holstein bull calves were exposed from wk 1 to 8 of life to 1 of 2 feed presentation treatments: concentrate and chopped grass hay (spent more time feeding than calves fed COM (56.7 vs. 46.8 min/d). In wk 8, calves fed MIX spent more time feeding (174.0 vs. 139.1 min/d) and had a lower rate of intake (11.5 vs. 14.7 g/min) compared with calves fed COM. Meal frequency was similar between treatments (12.2 meals/d). Diurnal feeding patterns in wk 8 were also affected by feed presentation, with calves fed MIX spending less time feeding at time of feed delivery and more time feeding throughout the rest of the daylight hours than calves fed COM. Diurnal feeding patterns of hay and concentrate in wk 8 differed for calves fed COM, with more time spent consuming hay at time of feed delivery and less time spent consuming hay throughout the rest of the day. Once calves previously fed COM were transitioned to the MIX diet in wk 9, meal frequency, meal duration, and diurnal feeding patterns were similar between treatments: both treatments spent similar amounts of time feeding (173.9 min/d) and had similar peaks in feeding activity at time of feed delivery, sunrise, and sunset. Provision of hay and concentrate to young calves as a mixed ration, compared with separate components, increases time spent feeding and results in more evenly distributed diurnal feeding patterns. However, differences in feeding patterns resulting from feed presentation did not persist after 8 wk of age, when all calves were fed a mixed ration. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

    Institute of Scientific and Technical Information of China (English)

    MA Fei; WU Jian-hua

    2012-01-01

    The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control.Based on the theoretical considerations,the experiments of the aerator for a discharge tunnel were conducted,and the relationships between the flow regime and hydraulic and geometric parameters were investigated.The results showed that,there are two kinds of threshold values for the flow regime conversions.One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity,and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity.Two empirical expressions were obtained for the conversions of the flow regimes,which can be used in the designs of the aerators.

  3. US Forest Service LANDFIRE Historical Fire Regimes

    Data.gov (United States)

    US Forest Service, Department of Agriculture — Historical fire regimes, intervals, and vegetation conditions are mapped using the Vegetation Dynamics Development Tool (VDDT). These data support fire and landscape...

  4. Figure 1: Basal-Bolus Regime

    African Journals Online (AJOL)

    Siegal_D

    Breakfast. Lunch. Dinner. Bedtime. Plasma insulin concentrations over time with a twice daily insulin mix regime .... Hypoglycaemia. Frequency, severity, awareness, precipitants, driving, ... Post GDM, family members, IGT etc. EXAMINATION.

  5. Regimes of validity for balanced models

    Science.gov (United States)

    Gent, Peter R.; McWilliams, James C.

    1983-07-01

    Scaling analyses are presented which delineate the atmospheric and oceanic regimes of validity for the family of balanced models described in Gent and McWilliams (1983a). The analyses follow and extend the classical work of Charney (1948) and others. The analyses use three non-dimensional parameters which represent the flow scale relative to the Earth's radius, the dominance of turbulent or wave-like processes, and the dominant component of the potential vorticity. For each regime, the models that are accurate both at leading order and through at least one higher order of accuracy in the appropriate small parameter are then identified. In particular, it is found that members of the balanced family are the appropriate models of higher-order accuracy over a broad range of parameter regimes. Examples are also given of particular atmospheric and oceanic phenomena which are in the regimes of validity for the different balanced models.

  6. The Two Regimes of Postwar Shipping

    DEFF Research Database (Denmark)

    Iversen, Martin Jes; Tenold, Stig

    2014-01-01

    The aim of this article is to illustrate the most important changes in the regulatory framework of the shipping sector from the 1960s to 2010, and to analyse the basis for, and effects of, these changes. In order to explain how the transformation has occurred, we use two traditional maritime...... nations—Denmark and Norway—as case studies. First, we introduce the two regimes of Danish and Norwegian shipping: ‘the national regime’ from the early 1960s to the mid-1970s; and ‘the competitive regime’, which was fully established by the middle of the 1990s and still persists. Then, we briefly sketch...... the bargaining that accompanied the shift from the national regime to the competitive regime. Specifically, we show that the new regime primarily accommodated the interests of private actors such as shipping companies, rather than the interests of the authorities and the trade unions....

  7. Exchange rate regimes and external financial stability

    Directory of Open Access Journals (Sweden)

    Stoica Ovidiu

    2016-01-01

    Full Text Available Financial stability within the framework of the global financial crisis has become a common topic for researchers and practitioners. In order to analyse the impact of exchange rate regimes on financial stability we use both the de jure and de facto exchange rate classifications. We apply the model to a 1999-2010 annual data sample for 135 countries and territories, grouped by the level of economic development. Our second focus is the investigation of the effects of the exchange rate regimes in three economic integration areas (member countries of the European Union 27, the Southern Common Market, and the Association of Southeast Asian Nations on financial stability. Our results generally support the central banks’ concerns that the flexibility of exchange rate regimes should be reduced in order to sustain financial stability; however, the findings are not robust when using alternative regime classifications.

  8. Estradiol differentially affects auditory recognition and learning according to photoperiodic state in the adult male songbird, European starling (Sturnus vulgaris

    Directory of Open Access Journals (Sweden)

    Rebecca M. Calisi

    2013-09-01

    Full Text Available Changes in hormones can affect many types of learning in vertebrates. Adults experience fluctuations in a multitude of hormones over a temporal scale, from local, rapid action to more long-term, seasonal changes. Endocrine changes during development can affect behavioral outcomes in adulthood, but how learning is affected in adults by hormone fluctuations experienced during adulthood is less understood. Previous reports have implicated the sex steroid hormone estradiol (E2 in both male and female vertebrate cognitive functioning. Here, we examined the effects of E2 on auditory recognition and learning in male European starlings (Sturnus vulgaris. European starlings are photoperiodic, seasonally breeding songbirds that undergo different periods of reproductive activity according to annual changes in day length. We simulated these reproductive periods, specifically 1. photosensitivity, 2. photostimulation, and 3. photorefractoriness in captive birds by altering day length. During each period, we manipulated circulating E2 and examined multiple measures of learning. To manipulate circulating E2, we used subcutaneous implants containing either 17-β E2 and/or fadrozole (FAD, a highly specific aromatase inhibitor that suppresses E2 production in the body and the brain, and measured the latency for birds to learn and respond to short, male conspecific song segments (motifs. We report that photostimulated birds given E2 had higher response rates and responded with better accuracy than those given saline controls or FAD. Conversely, photosensitive, animals treated with E2 responded with less accuracy than those given FAD. These results demonstrate how circulating E2 and photoperiod can interact to shape auditory recognition and learning in adults, driving it in opposite directions in different states.

  9. A domestication related mutation in the thyroid stimulating hormone receptor gene (TSHR) modulates photoperiodic response and reproduction in chickens.

    Science.gov (United States)

    Karlsson, Anna-Carin; Fallahshahroudi, Amir; Johnsen, Hanna; Hagenblad, Jenny; Wright, Dominic; Andersson, Leif; Jensen, Per

    2016-03-01

    The thyroid stimulating hormone receptor gene (TSHR) has been suggested to be a "domestication locus" in the chicken. A strong selective sweep over TSHR in domestic breeds together with significant effects of a mutation in the gene on several domestication related traits, indicate that the gene has been important for chicken domestication. TSHR plays a key role in the signal transduction of seasonal reproduction, which is characteristically less strict in domestic animals. We used birds from an advanced intercross line between ancestral Red Junglefowl (RJF) and domesticated White Leghorn (WL) to investigate effects of the mutation on reproductive traits as well as on TSHB, TSHR, DIO2 and DIO3 gene expression during altered day length (photoperiod). We bred chickens homozygous for either the mutation (d/d) or wild type allele (w/w), allowing assessment of the effect of genotype at this locus while also controlling for background variation in the rest of the genome. TSHR gene expression in brain was significantly lower in both d/d females and males and d/d females showed a faster onset of egg laying at sexual maturity than w/w. Furthermore, d/d males showed a reduced testicular size response to decreased day length, and lower levels of TSHB and DIO3 expression. Additionally, purebred White Leghorn females kept under natural short day length in Sweden during December had active ovaries and lower levels of TSHR and DIO3 expression compared to Red Junglefowl females kept under similar conditions. Our study indicates that the TSHR mutation affects photoperiodic response in chicken by reducing dependence of seasonal reproduction, a typical domestication feature, and may therefore have been important for chicken domestication.

  10. Effects of temperature and photoperiod on the aestivo-hibernal egg diapause of Scymnus camptodromus (Coleoptera: Coccinellidae).

    Science.gov (United States)

    Keena, Melody A; Trotter, R Talbot; Cheah, Carole; Montgomery, Michael E

    2012-12-01

    Three sequential studies were conducted on the interacting effects of exposure to low (5°C) temperature for 0, 7, 28, 56, or 84 d followed by incubation at 10, 15, or 20°C on the egg diapause of Scymnus (Neopullus) camptodromus Yu and Liu (Coleoptera: Coccinellidae). This beetle was imported from China as a potential biological control agent for hemlock woolly adelgid, Adelges tsugae (Annand) (Hemiptera: Adelgidae). Very few eggs laid and held at a constant 15 or 20°C showed any indication of development. Only eggs exposed to temperature combinations of 5 and 10°C had >50% hatch. Highest percent hatch and fastest development occurred when eggs were held at 5°C for 56 or 84 d followed by holding at 10°C. A model estimated the lower threshold for postdiapause development to be 2°C. The effect of temperature on egg hatch was similar at photoperiods of 12:12 and 16:8 (L:D) h, suggesting egg development is not governed by photoperiod or light exposure. Collectively these data indicate that S. camptodromus eggs laid in the spring and summer go through an aestivo-hibernal diapause that is maintained by warm temperatures and that development resumes when temperatures drop, in parallel with the development of hemlock woolly adelgid. This concurrent development allows S. camptodromus eggs to hatch while hemlock woolly adelgid is laying eggs. This synchrony between the development of S. camptodromus eggs and the overwintering adelgid suggest this beetle may be a good candidate for the biological control of the hemlock woolly adelgid.

  11. The influence of photoperiod and light intensity on the growth and photosynthesis of Dunaliella salina (chlorophyta) CCAP 19/30.

    Science.gov (United States)

    Xu, Yanan; Ibrahim, Iskander M; Harvey, Patricia J

    2016-09-01

    The green microalga Dunaliella salina survives in a wide range of salinities via mechanisms involving glycerol synthesis and degradation and is exploited for large amounts of nutraceutical carotenoids produced under stressed conditions. In this study, D. salina CCAP 19/30 was cultured in varying photoperiods and light intensities to study the relationship of light with different growth measurement parameters, with cellular contents of glycerol, starch and carotenoids, and with photosynthesis and respiration. Results show CCAP 19/30 regulated cell volume when growing under light/dark cycles: cell volume increased in the light and decreased in the dark, and these changes corresponded to changes in cellular glycerol content. The decrease in cell volume in the dark was independent of cell division and biological clock and was regulated by the photoperiod of the light/dark cycle. When the light intensity was increased to above 1000 μmol photons m(-2) s(-1), cells displayed evidence of photodamage. However, these cells also maintained the maximum level of photosynthesis efficiency and respiration possible, and the growth rate increased as light intensity increased. Significantly, the intracellular glycerol content also increased, >2-fold compared to the content in light intensity of 500 μmol photons m(-2) s(-1), but there was no commensurate increase in the pool size of carotenoids. These data suggest that in CCAP 19/30 glycerol stabilized the photosynthetic apparatus for maximum performance in high light intensities, a role normally attributed to carotenoids.

  12. Low-temperature acclimation of barley cultivars used as parents in mapping populations: response to photoperiod, vernalization and phenological development.

    Science.gov (United States)

    Limin, Allen; Corey, Ann; Hayes, Patrick; Fowler, D Brian

    2007-06-01

    Six barley (Hordeum vulgare L.) accessions, previously used as parents of mapping populations, were evaluated for characters potentially affecting the location of low-temperature (LT) tolerance QTLs. Three were of winter growth habit (Kompolti Korai, Nure, and Strider), one was facultative (Dicktoo) and two were spring (Morex and Tremois). Final leaf number (FLN) and LT(50 )were determined at weekly intervals from 0 to 98 days of LT acclimation/vernalization under both long day (LD) and short day (SD) photoperiods. The point of vegetative/reproductive transition was determined from measurements of double ridge (DR) formation and FLN. With the exception of Nure, SD delayed development by increasing leaf production. Dicktoo was extremely SD sensitive lengthening its vegetative phase by more than 63 days relative to the LD photoperiod. SD had the opposite effect on Nure, causing an accelerating of flowering exhibiting the characteristic of 'short day vernalization'. All accessions except Dicktoo and Kompolti Korai acclimated rapidly in the first 7 days of LT exposure, approaching their maximum LT tolerance in 14-21 days. Dicktoo and Kompolti Korai continued to slowly acclimate until reproductive transition. The results emphasize two important points: (1) the location of QTLs for LT tolerance, and as a consequence the identification of putative candidate genes, will be a function of the genotypes sampled, the experimental conditions used, and the quality of the phenotypic data and (2) the barley LT tolerance pathway reaches an early impediment relative to closely related more hardy members of the Triticeae such as wheat and rye.

  13. Photoperiodism as a modifier of effect of extremely low-frequency electromagnetic field on morphological properties of pineal gland.

    Science.gov (United States)

    Lukac, Tamara; Matavulj, Amela; Matavulj, Milica; Rajković, Vesna; Lazetić, Bogosav

    2006-08-01

    The aim of our study was to determine, using histological and stereological methods, whether photoperiodism has any impact on the effects that chronic (three-month long) exposure to LF-EMF (50Hz) has on morphological characteristics on rat's pineal gland. The experiment was performed on 48 Mill Hill male rats (24 experimental and 24 control). Upon birth, 24 rats were exposed for 7h a day, 5 days a week for 3 months to LF-EMF (50 Hz, 50-500microT, 10V/m). In the winter (short days, long nights), the activity of the pineal gland and neuroendocrine sensitivity is increased. The study was performed both during summer and winter, following the identical protocol. After sacrifice of animals, samples of pineal gland were processed for HE staining and then were analyzed using the methods of stereology. The most significant changes in epiphysis in the first group of animals in wintertime are: altered glandular feature, hyperemia, reduced pinealocytes with pale pink, poor cytoplasm and irregular, stick-form nuclei. In the second group (II) pinealocytes are enlarged, with vacuolated cytoplasm and hyper chromatic, enlarged nucleus. Morphological changes of pineal gland at rats in the summertime were not as intense as in the winter and finding of the gland in the group II is compatible with those from the control group. Stereological results show both in winter and summer in the first group the decrease of volume density of pinealocytes, their cytoplasm and nuclei and in the second group in winter increase the volume density of pinealocytes, cytoplasm and nuclei, while in the second group the results in summertime are equal to those from the control group. Photoperiodism is modifier of effect of LF-EMF on morphological structure of pineal gland, because the gland recovery is incomplete in winter and reversible in summer.

  14. Photoperiodic changes in endocannabinoid levels and energetic responses to altered signalling at CB1 receptors in Siberian hamsters.

    Science.gov (United States)

    Ho, J M; Smith, N S; Adams, S A; Bradshaw, H B; Demas, G E

    2012-07-01

    Siberian hamsters (Phodopus sungorus) adapt to seasonal environmental conditions with marked changes in body mass, primarily in the form of adiposity. Winter-like conditions (e.g. short days) are sufficient to decrease body mass by approximately 30% in part via reductions in food intake. The neuroendocrine mechanisms responsible for these changes are not well understood, and homeostatic orexigenic/anorexigenic systems of the hypothalamus provide little explanation. We investigated the potential role of endocannabinoids, which are known modulators of appetite and metabolism, in mediating seasonal changes in energy balance. Specifically, we housed hamsters in long or short days for 0, 3, or 9 weeks and measured endocannabinoid levels in the hypothalamus, brainstem, liver and retroperitoneal white adipose tissue (RWAT). An additional group of males housed in short days for 25 weeks were also compared with long-day controls. Following 9 weeks in short days, levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) were significantly elevated in RWAT and reduced in brainstem, although they returned to long-day levels by week 25 in short-day males that had cycled back to summer-like energy balance. Endocannabinoid levels in these tissues correlated significantly with adiposity and change in body mass. No photoperiodic changes were observed in the hypothalamus or liver; however, sex differences in 2-AG levels were found in the liver (males > females). We further tested the effects of CB(1) receptor signalling on ingestive behaviour. Five daily injections of CB(1) antagonist SR141716 significantly reduced food intake and body mass but not food hoarding. Although the CB(1) agonist arachidonyl-2-chloroethylamide did not appreciably affect either ingestive behaviour, body mass was significantly elevated following 2 days of injections. Taken altogether, these findings demonstrate that endocannabinoid levels vary with sex and photoperiod in a site-specific manner, and that

  15. Photoperiod-dependent regulation of carboxypeptidase E affects the selective processing of neuropeptides in the seasonal Siberian hamster (Phodopus sungorus).

    Science.gov (United States)

    Helwig, M; Herwig, A; Heldmaier, G; Barrett, P; Mercer, J G; Klingenspor, M

    2013-02-01

    The production of bioactive peptides from biologically inactive precursors involves extensive post-translational processing, including enzymatic cleavage by proteolytic peptidases. Endoproteolytic prohormone-convertases initially cleave the precursors of many neuropeptides at specific amino acid sequences to generate intermediates with basic amino acid extensions on their C-termini. Subsequently, the related exopeptidases, carboxypeptidases D and E (CPD and CPE), are responsible for removing these amino acids before the peptides achieve biological activity. We investigated the effect of photoperiod on the processing of the neuropeptide precursor pro-opiomelanocortin (POMC) and its derived neuropeptides, α-melanocyte-stimulating hormone (MSH) and β-endorphin (END), within the hypothalamus of the seasonal Siberian hamster (Phodopus sungorus). We thus compared hypothalamic distribution of CPD, CPE, α-MSH and β-END using immunohistochemistry and measured the enzyme activity of CPE and concentrations of C-terminally cleaved α-MSH in short-day (SD; 8 : 16 h light/dark) and long-day (LD; 16 : 8 h light/dark) acclimatised hamsters. Increased immunoreactivity (-IR) of CPE, as well as higher CPE activity, was observed in SD. This increase was accompanied by more β-END-IR cells and substantially higher levels of C- terminally cleaved α-MSH, as determined by radioimmunoassay. Our results suggest that exoproteolytic cleavage of POMC-derived neuropeptides is tightly regulated by photoperiod in the Siberian hamster. Higher levels of biological active α-MSH- and β-END in SD are consistent with the hypothesis that post-translational processing is a key event in the regulation of seasonal energy balance.

  16. Photoperiod length and the estrus synchronization protocol used before AI affect the twin pregnancy rate in dairy cattle.

    Science.gov (United States)

    Andreu-Vázquez, C; Garcia-Ispierto, I; López-Gatius, F

    2012-10-01

    This study addresses potential management risk factors affecting the incidence of twin pregnancies in high-producing dairy cows. Special attention was paid to the estrus synchronization protocol used before the AI resulting in pregnancy. Possible factors affecting the twin pregnancy rate were analyzed through binary logistic regression procedures on 2015 pregnant cows from July 2010 to July 2011. Twin pregnancy was recorded in 361 of the 2015 pregnancy diagnoses made (17.9%). Twin pregnancy rates differed among herds (P twin pregnancy was reduced by factors of 0.65 or 0.71 when AI was performed during the warm season or an increasing photoperiod, respectively and increased by a factor of 1.11 for each unit increase in lactation number; by factors of 4.57 or 6.33 in cows that received a progesterone-releasing intravaginal device (PRID) plus 500 or 750 IU of equine chorionic gonadotropin (eCG) 28 days before the pregnancy AI, respectively; by a factor of 2.39 in cows with an ovarian cyst diagnosed in the 14 days prior to AI and treated with prostaglandins (PG); by factors of 1.94 or 3.91 in cows that received two PG doses during the 14 days prior to AI or cows that following failed PRID treatment had received PG started over the 28 days prior to AI, respectively; and by a factor of 2.58 in cows that had previously delivered twins compared to cows delivering singletons. Our results indicate that cow factors, such as lactation number and previous twining, as well as environmental factors, such as photoperiod and season and management related to synchronization protocols affect significantly the incidence of twin pregnancies.

  17. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2010-01-01

    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  18. International Experiences with Different Monetary Policy Regimes

    OpenAIRE

    Mishkin, Frederic S.

    1999-01-01

    In recent years a growing consensus has emerged for price stability as the overriding, long-run goal of monetary policy. However, despite this consensus, the following question still remains: how should monetary policy be conducted to achieve the price stability goal? This paper examines the experience with different monetary policy regimes currently in use in a number of countries to shed light on this question. A central feature of all of the monetary regimes discussed here is the ise of a ...

  19. Feed the dogs

    DEFF Research Database (Denmark)

    Knudsen, Gry Høngsmark; Bajde, Domen

    2016-01-01

    MedieKultur | Journal of media and communication research | ISSN 1901-9726Article – Open sectionPublished by SMID | Society of Media researchers In Denmark | www.smid.dkTh e online version of this text can be found open access at www.mediekultur.dk196Feed the dogsA case of humanitarian communicat......MedieKultur | Journal of media and communication research | ISSN 1901-9726Article – Open sectionPublished by SMID | Society of Media researchers In Denmark | www.smid.dkTh e online version of this text can be found open access at www.mediekultur.dk196Feed the dogsA case of humanitarian...

  20. Live feeds in aquaculture

    OpenAIRE

    Dhert, Ph.; Sorgeloos, P

    1995-01-01

    Over the past two decades intensive larviculture of several fish and shellfish species has expanded into a multimillion dollar industry. Although much progress has been made in identifying the dietary requirements of the larvae of various aquaculture species, the mass culture of their early larval stages still requires the use of live feeds. Selected either through trial and error approaches or because of their convenience in mass production and use, hatcheries are relying today on three grou...

  1. Feed sources for livestock

    OpenAIRE

    Zanten, van, H.H.E.

    2016-01-01

    Production of food has re-emerged at the top of the global political agenda, driven by two contemporary challenges: the challenge to produce enough nutritious food to feed a growing and more prosperous human population, and the challenge to produce this food in an environmentally sustainable way. Current levels of production of especially animal-source food (ASF), pose severe pressure on the environment via their emissions to air, water, and soil; and their use of scarce resources, such as la...

  2. Residual Feed Intake

    OpenAIRE

    Sainz, Roberto D.; Paulino, Pedro V.

    2004-01-01

    Introduction Low rates of return on investment for livestock operations are a fact of life. Producers have little impact on the market price for their cattle; therefore management must be focused on the things producers can actually do something about. For many years, genetic selection programs have focused on production (output) traits, with little attention given to production costs (inputs). Recently, this view has begun to change, and the efficiency of conversion of feed (i.e., t...

  3. First feeding of larval herring

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Munk, Peter; Støttrup, Josianne

    1985-01-01

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

  4. Coupling between crossed dipole feeds

    DEFF Research Database (Denmark)

    Andersen, J.; Schjær-Jacobsen, Hans; Lessow, H.

    1974-01-01

    as a function of orientation and feeding network properties. The antennas are used as feeds for a parabolic reflector, and the effect of coupling on the secondary fields is analyzed. Especially significant is the polarization loss and it may, to some extent, be reduced by a proper choice of feeding network....

  5. Food Safety Information RSS feed

    Data.gov (United States)

    U.S. Department of Health & Human Services — This is an RSS Feed of Food Safety information that’s produced in real-time by the CDC. This RSS feed is the integration of two other XML feeds, one from the USDA's...

  6. Multiple part feeding

    DEFF Research Database (Denmark)

    Hvilshøj, Mads; Bøgh, Simon; Nielsen, Oluf Skov

    2012-01-01

    Purpose - The purpose of this paper is to present experience from a real-world demonstration of autonomous industrial mobile manipulation (AIMM) based on the mobile manipulator "Little Helper" performing multiple part feeding at the pump manufacturer Grundfos A/S. Design/methodology/approach - Th......Purpose - The purpose of this paper is to present experience from a real-world demonstration of autonomous industrial mobile manipulation (AIMM) based on the mobile manipulator "Little Helper" performing multiple part feeding at the pump manufacturer Grundfos A/S. Design....../methodology/approach - The necessary AIMM technologies exist at a mature level - the reason that no mobile manipulators have yet been implemented in industrial environments, is that research in the right applications have not been carried out. We propose a pragmatic approach consisting of: a commercial-off-the-shelf (COTS) mobile...... manipulator system design ("Little Helper"), a suitable and comprehensive industrial application (multiple part feeding), and a general implementation concept for industrial environments (the "Bartender Concept"). Findings - Results from the three days of real-world demonstration show that "Little Helper...

  7. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  8. Growth, survival, and fatty acid composition of coppernose bluegill offered different winter feeding regimes

    Science.gov (United States)

    Winter fish losses are routinely reported by Arkansas sportfish producers in the spring. Juvenile centrarchid species (less than 7.6 cm) are quite susceptible to harsh winter conditions. While some of these winter fish losses can be attributed to predation by fish eating birds and water quality fact...

  9. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  10. International standardization of cage designs and feeding regimes for honey bee in vitro experiments

    Science.gov (United States)

    The aim of this study was to improve and standardize cage systems for maintaining adult honey bee workers under in vitro laboratory conditions. To achieve this goal, we experimentally evaluated the impact of different cages, developed by scientists of the international research network COLOSS (Preve...

  11. Protein synthesis, growth and energetics in larval herring (Clupea harengus) at different feeding regimes

    DEFF Research Database (Denmark)

    Houlihan, D F; Pedersen, B H; Steffensen, J F

    1995-01-01

    approximately 50% during rapid growth. Rapid growth in herring larvae thus appears to be characterized by moderate levels of protein turnover similar to those obtained for larger fish. Increases in growth rate occurred without changes in RNA concentration, i.e., the larvae increased the efficiency of RNA...

  12. Fiscal Policy and Welfare under Different Exchange Rate Regimes

    DEFF Research Database (Denmark)

    Østrup, Finn

    regime in whichthe monetary authority optimises preferences which include an employment targetand an inflation target. As government spending affects the representativeindividual's utility, the choice of exchange rate regime has an impact on welfare.Keywords: exchange rate regimes; fiscal policy...

  13. Causas estruturais e consequências dos regimes internacionais: regimes como variáveis intervenientes

    OpenAIRE

    Stephen D. Krasner

    2012-01-01

    Os regimes internacionais são definidos como princípios, normas, regras e procedimentos de tomada de decisões ao redor dos quais as expectativas dos atores convergem em uma dada área-tema. Como ponto de partida, os regimes são conceituados como variáveis intervenientes, estando entre fatores causais básicos e os resultados e comportamentos relacionados. Há três visões a respeito da importância dos regimes: as orientações estruturais convencionais desvalorizam os regimes como sendo, na melhor ...

  14. Fermented liquid feed for pigs.

    Science.gov (United States)

    Missotten, Joris A M; Michiels, Joris; Ovyn, Anneke; De Smet, Stefaan; Dierick, Noël A

    2010-12-01

    Since the announcement of the ban on the use of antibiotics as antimicrobial growth promoters in the feed of pigs in 2006 the investigation towards alternative feed additives has augmented considerably. Although fermented liquid feed is not an additive, but a feeding strategy, the experimental work examining its possible advantages also saw a rise. The use of fermented liquid feed (FLF) has two main advantages, namely that the simultaneous provision of feed and water may result in an alleviation of the transition from the sow milk to solid feed and may also reduce the time spent to find both sources of nutrients, and secondly, that offering FLF with a low pH may strengthen the potential of the stomach as a first line of defence against possible pathogenic infections. Because of these two advantages, FLF is often stated as an ideal feed for weaned piglets. The results obtained so far are rather variable, but in general they show a better body weight gain and worse feed/gain ratio for the piglets. However, for growing-finishing pigs on average a better feed/gain ratio is found compared to pigs fed dry feed. This better performance is mostly associated with less harmful microbiota and better gut morphology. This review provides an overview of the current knowledge of FLF for pigs,dealing with the FLF itself as well as its effect on the gastrointestinal tract and animal performance.

  15. First feeding of larval herring

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Munk, Peter; Støttrup, Josianne

    1985-01-01

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

  16. Analysis of self-feeding in children with feeding disorders.

    Science.gov (United States)

    Rivas, Kristi M; Piazza, Cathleen C; Roane, Henry S; Volkert, Valerie M; Stewart, Victoria; Kadey, Heather J; Groff, Rebecca A

    2014-01-01

    In the current investigation, we evaluated a method for increasing self-feeding with 3 children with a history of food refusal. The children never (2 children) or rarely (1 child) self-fed bites of food when the choice was between self-feeding and escape from eating. When the choice was between self-feeding 1 bite of food or being fed an identical bite of food, self-feeding was low (2 children) or variable (1 child). Levels of self-feeding increased for 2 children when the choice was between self-feeding 1 bite of food or being fed multiple bites of the same food. For the 3rd child, self-feeding increased when the choice was between self-feeding 1 bite of food or being fed multiple bites of a less preferred food. The results showed that altering the contingencies associated with being fed increased the probability of self-feeding, but the specific manipulations that produced self-feeding were unique to each child.

  17. Feeding and Swallowing Disorders (Dysphagia) in Children

    Science.gov (United States)

    ... for the Public / Speech, Language and Swallowing / Swallowing Feeding and Swallowing Disorders (Dysphagia) in Children What are ... children with feeding and swallowing disorders ? What are feeding and swallowing disorders? Feeding disorders include problems gathering ...

  18. Feeding Tips For Your Baby with CHD

    Science.gov (United States)

    ... How To Feed Your Baby Either breast- or bottle-feeding works well for babies with heart problems, but ... do best with a combination of breast- and bottle-feeding. Breast-Feeding Your Baby If your baby is ...

  19. Reproduction and feeding of the electric fish Brachyhypopomus gauderio (Gymnotiformes: Hypopomidae and the discussion of a life history pattern for gymnotiforms from high latitudes.

    Directory of Open Access Journals (Sweden)

    Julia Giora

    Full Text Available The reproductive biology and feeding habits of the electric fish Brachyhypopomus gauderio were studied. The species has seasonal reproductive behavior, with breeding occurring during the Southern Hemisphere spring and summer, and having a positive relation with the photoperiod variation. Brachyhypopomus gauderio was defined as a fractional spawner, with low relative fecundity and high first maturation size. Sexual dimorphism was registered, males undergoing hypertrophy of the distal portion of caudal filament. The results on reproductive biology herein obtained are in agreement with data concerning gymnotiforms from Southern Brazil and Uruguay, pointing to an ecological pattern for the species from high latitudes, differing from species with tropical distribution. According to the analysis of the food items, B. gauderio feed mainly on autochthonous insects, likewise the other gymnotiforms previously investigated, leading to conclude that there is no variation on the diet of the species of the order related to climatic conditions or even to habitat of occurrence.

  20. Reproduction and feeding of the electric fish Brachyhypopomus gauderio (Gymnotiformes: Hypopomidae) and the discussion of a life history pattern for gymnotiforms from high latitudes.

    Science.gov (United States)

    Giora, Julia; Tarasconi, Hellen M; Fialho, Clarice B

    2014-01-01

    The reproductive biology and feeding habits of the electric fish Brachyhypopomus gauderio were studied. The species has seasonal reproductive behavior, with breeding occurring during the Southern Hemisphere spring and summer, and having a positive relation with the photoperiod variation. Brachyhypopomus gauderio was defined as a fractional spawner, with low relative fecundity and high first maturation size. Sexual dimorphism was registered, males undergoing hypertrophy of the distal portion of caudal filament. The results on reproductive biology herein obtained are in agreement with data concerning gymnotiforms from Southern Brazil and Uruguay, pointing to an ecological pattern for the species from high latitudes, differing from species with tropical distribution. According to the analysis of the food items, B. gauderio feed mainly on autochthonous insects, likewise the other gymnotiforms previously investigated, leading to conclude that there is no variation on the diet of the species of the order related to climatic conditions or even to habitat of occurrence.