Nutritional Inputs Research Articles

Evidence for similar changes in offspring phenotype following either maternal undernutrition or overnutrition: potential impact on fetal epigenetic mechanisms

The goal of this review is to shed light on the role of maternal malnutrition in inducing epigenetic changes in gene expression, leading to alterations in fetal growth and development, and to altered postnatal phenotype and the development of metabolic disease. We present evidence supporting the concept that both maternal undernutrition and overnutrition can induce the same cadre of fetal organ and tissue abnormalities and lead to the same postnatal metabolic changes in the resulting offspring. Furthermore, we present evidence that in both overnourished and undernourished ovine pregnancies, fetuses experience a period of nutrient restriction as a result of alterations in placental delivery of maternal nutrients into the fetal compartment. We argue that this bout of reduced fetal nutrition in undernourished and overnourished pregnancies leads to the development of a thrifty phenotype in which the fetus attempts to alter the function of its tissues and organs to maximise its chances of survival in a postnatal environment that is deficient in nutrients. Importantly, we present evidence to support the concept that these phenotypic changes in offspring quality resulting from maternal malnutrition are transmitted to subsequent generations, independent of their maternal nutritional inputs.

Effects of dietary crude protein on fertility: Meta-analysis and meta-regression

Studies used to evaluate effects of dietary intervention on fertility may be subject to confounding because modification of one nutritional input requires a change in at least one other input. Meta-analytical modeling allows examination of a main intervention for a series of studies, but also an examination of a series of related effects through use of meta-regression. Effects of dietary crude protein (CP) on fertility were examined using this approach. We obtained 21 studies containing 32 comparisons that had pregnancy or conception data and met the eligibility criteria for meta-analysis of randomized controlled experiments providing information on diets used. Publications that contained data on prospective, randomized controlled experiments examining effects of dietary CP, either concentrations or degradability, or effects of a specific feed ingredient intervention on fertility were identified. Details on dietary formulation and diet intake were extracted from the publications, as were measures of urea in blood or plasma. Estimated fixed and random effects relative risks showed that risk of conception was lower in cows fed higher CP or more degradable CP diets (fixed effect (Mantel–Haenszel Relative Risk) = 0.91 (95% CI 0.84–0.98); P=0.019). This effect was homogenous ( I 2 = 0) and not influenced by difference in blood urea N, duration of intervention, breed, parity, milk production or type of diet delivery. Significant associations among CP components of the diet and carbohydrate fractions supported the hypothesized potential for confounding, but only the amount of soluble CP eaten was a significant meta-regression covariate that reduced risk of conception. There was no evidence that the significant reduction in fiber or non-fiber carbohydrate (NFC) fractions of the diets associated with increased concentration of CP, soluble CP or rumen degradable fractions or soyabean products content of the diet influenced conception rates. Results support findings of experiments showing that increased intake of soluble CP reduced conception rates, and provides strong evidence that increased concentrations of CP or increased degradability of CP, within the ranges evaluated in the studies contributing to this meta-analysis, reduce the risk of conception in lactating dairy cattle.

Why be a cannibal? The benefits to cane toad, Rhinella marina [= Bufo marinus], tadpoles of consuming conspecific eggs

Unlike many species that are ‘occasional’ cannibals, the tadpoles of cane toads specifically target conspecific eggs for consumption, ignoring the eggs of sympatric frog species (at least within the toads’ current invasive range in Australia). We tested three hypotheses as to the benefits of consuming conspecific eggs: transfer of toxins from eggs (which have high toxin content) to tadpoles (which have lower toxin content), nutritional input, and reduction of future competition. We found no evidence of toxin transfer, but eggs contained sufficient nutrition for cannibalistic tadpoles to develop through to metamorphosis, and egg consumption enhanced rates of tadpole growth and differentiation through reduction of subsequent competition from younger tadpoles. Features of the cane toads’ life history (e.g. synchronized deposition and development of all eggs within a clutch; delay between hatching and onset of feeding; short larval stage relative to interclutch interval of a given adult female) mean that the cannibals are unlikely to be close relatives of the younger conspecifics they consume (either as eggs or as metamorphs). Kin selection may thus favour rather than oppose cannibalism . The end result is that cannibalistic toad tadpoles benefit through nutrition and reduced future competition, with little collateral risk of eating their own siblings. Another potential cost of cannibalism (risk of disease transmission) may be minimal in this system, because the eggs are unlikely to contain pathogens (reflecting their brief embryonic periods and protective jelly layers). The combination of these forces has favoured the evolution of targeted cannibalism by cane toad tadpoles.

A new model for caste development in social wasps.

Specialization into reproductive and non-reproductive castes is one of the defining traits of eusocial insects. Knowledge of the proximal causes of caste differentiation is therefore central to achieving an understanding of the evolution of eusociality. Castes are an example of a polyphenism, multiple, discrete phenotypes arising from a single genotype in response to differing environmental conditions. Here we focus on recent work in the social wasps to provide insight into how environmental conditions may trigger the development of caste across a range from independent- to swarm-founding social species. The amount of food larvae receive has long been recognized as a key input factor in the determination of caste, but that alone is insufficient to account for the range of combinations of size, development time and caste among the female offspring of Polistes, an independent-founding wasp. Recent experimental work on P. fuscatus has shown that vibrations that are associated with the feeding of larvae are another essential environmental input in the determination of caste. we present a model of how vibrational signaling in the context of feeding larvae could interact with nutritional input to account for the developmental patterns seen in these wasps. Mapping the distribution of vibrational signaling onto a phylogeny of the social wasps suggests that this trait characterized the common ancestor of the subfamilies vespinae + Polistinae, diversified in the independent-founding species, then was superseded by caste-determining mechanisms in the swarm-founding and vespine species that function more effectively in larger colonies.

Neuroendocrine regulation of Drosophila metamorphosis requires TGFβ/Activin signaling

In insects, initiation of metamorphosis requires a surge in the production of the steroid hormone 20-hydroxyecdysone from the prothoracic gland, the primary endocrine organ of juvenile larvae. Here, we show that blocking TGFβ/Activin signaling, specifically in the Drosophila prothoracic gland, results in developmental arrest prior to metamorphosis. The terminal, giant third instar larval phenotype results from a failure to induce the large rise in ecdysteroid titer that triggers metamorphosis. We further demonstrate that activin signaling regulates competence of the prothoracic gland to receive PTTH and insulin signals, and that these two pathways act at the mRNA and post-transcriptional levels, respectively, to control ecdysone biosynthetic enzyme expression. This dual regulatory circuitry may provide a cross-check mechanism to ensure that both developmental and nutritional inputs are synchronized before initiating the final genetic program leading to reproductive adult development. As steroid hormone production in C. elegans and mammals is also influenced by TGFβ/Activin signaling, this family of secreted factors may play a general role in regulating developmental transitions across phyla.

A service review of dietetic input for chronic obstructive pulmonary disease patients on long-term oral nutritional support

Background: Patients with chronic obstructive pulmonary disease (COPD) often require long-term oral nutritional support and concomitant dietetic input, secondary to commonly associated weight loss and malnutrition (Batres, 2007). There are approximately 100 000 people in Scotland living with COPD(NHS QIS, 2009). Due to current demands on dietetic services, this retrospective case review looked to explore the number of dietetic reviews provided and the consequent change in nutritional status in a group of COPD patients. Methods: A retrospective case review of the 26 COPD patients known to the community dietetic department at the time of the study was carried out (12 females, 14 males). The patient's ranged in age from 44 to 73 with the mean (SD) age of 64 (7.5) years. Their reported heights were recorded and each patient had their weight measured on Tanita scales at each contact. Initial BMI and current BMI were then calculated, together with the number of dietetic reviews that had been provided. The results were then analysed using SPSS statistics software. Recorded BMI data was parametric therefore a paired sample T-Test was used. Results: The median number of dietetic reviews was 6 (IQR 3, 10). From this, two patient groups were formed, those receiving six or less dietetic reviews and those with over 6. The T-Test indicated a significant increase between the initial BMI and current BMI for the group receiving six or less reviews (P = <0.005). This was not significant for the group who received over six reviews. Table 1. Mean (SD) body mass index (BMI) according to number of dietetic reviews BMI on referral (kg m-2) Current BMI (kg m-2) P value Six or less dietetic reviews (n = 14) 18.1 ± 3.3 19.6 ± 3.4 ≤0.005 Over six dietetic reviews (n = 12) 18.5 ± 1.9 18.2 ± 2.3 0.424 Discussion: This review supports previous research that dietary counseling and food fortification has a positive impact on the nutritional status of COPD patients (Weekes, 2009). It indicates that dietetic input is valuable, however, due to current demands on dietetic services, it is not beneficial to continually review this patient group long-term, once nutritional stability has been established, e.g. <5% weight loss in 3–6 months (BAPEN, 2004). Due to the clinical nature of the study, the limitations included the variable timescales for dietetic reviews. Conclusion: Dietetic input has a positive effect on BMI status in COPD patients however more efficient dietetic practices need to be implemented for long-term oral nutritional support patients.

Foraminifera in the diet of coral reef fish from the lagoon of New Caledonia: Predation, digestion, dispersion

Marine benthic Foraminifera are abundant and thus represent a potential food source for fish. Previous studies of Foraminifera in fish diets have examined only small samples, with significant input reported only for a single surface-feeding species of fish. The present study is the first based on a significant sample (247 fish belonging to 83 species, 291 species of Foraminifera identified from more than 20,000 specimens examined). It provides new information on the contribution of Foraminifera to fish diets, and on the impact of fish predation on Foraminifera. The planktonic Tretomphalus phases, selectively ingested by Pomacentrus amboinensis, were the only significant nutritional input from Foraminifera. Herbivorous fish accidentally ingested living epiphytic Foraminifera, which were still living after digestion, and were defecated, with a significant effect on their dispersion. Carnivorous fish ingested a small number of tests, which were generally altered by the acidic phase of digestion and had no impact on foraminiferal assemblages. Sediment feeders ingested large quantities of empty tests that were released elsewhere, suggesting a possible bias in paleontological interpretations by mixing the thanatocoenoses. Observations on gut contents showed that the fish sometimes fed on a wide range of food, changing with food availability and individual preferences of fish.

Effect of nutrition on Crassostrea gigas larval development and the evolution of physiological indices. Part A: Quantitative and qualitative diet effects

Several quality indices have been defined for marine bivalve larvae, including the coloration of whole larvae and the Triacylglycerols/Sterols ratio (TAG/ST), putting emphasis on the role of lipids in larval development. Using an image analysis system, epifluorescence microscopy and Nile Red, to specifically colour the reserves, we improved and quantified the overall physiological index based on the ratio of the lipid surface to the total larval surface. This Overall Lipid Index (OLI) was then tested in two experiments on the influence of nutritional parameters on larval development and metamorphosis in Crassostrea gigas, following the parallel evolution of the indices. The higher the input of microalgae, the quicker larvae developed, leading to a maximum development rate of 16.5 µm d − 1 . This rate was accompanied by the highest lipid reserves. At the end of rearing, the lipid reserves occupied 30% of the larval surface in the batches with the highest food ration, while they only covered 12% in the larvae on the lowest ration. In the same way, the TAG/ST ratio increased over the rearing period and reached its highest levels in larvae with the highest food ration. We also noted that the decrease in lipids over the first week of rearing was higher when the nutritional input was lower. Finally, deficient reserves and poor performances were recorded in larvae fed only the flagellates Pavlova lutheri (P), Isochrysis affinis galbana (T) or a mixture of these species (PT). In contrast, a high lipid accumulation and better performances were shown when the diet was based on the diatom C. calcitrans f. pumilum (Cp), whether alone or in combination with other species.

Forage collection, substrate preparation, and diet composition in fungus‐growing ants

1. Variation and control of nutritional input is an important selective force in the evolution of mutualistic interactions and may significantly affect coevolutionary modifications in partner species.2. The attine fungus‐growing ants are a tribe of more than 230 described species (12 genera) that use a variety of different substrates to manure the symbiotic fungus they cultivate inside the nest. Common ‘wisdom’ is that the conspicuous leaf‐cutting ants primarily use freshly cut plant material, whereas most of the other attine species use dry and partly degraded plant material such as leaf litter and caterpillar frass, but systematic comparative studies of actual resource acquisition across the attine ants have not been done.3. Here we review 179 literature records of diet composition across the extant genera of fungus‐growing ants. The records confirm the dependence of leaf‐cutting ants on fresh vegetation but find that flowers, dry plant debris, seeds (husks), and insect frass are used by all genera, whereas other substrates such as nectar and insect carcasses are only used by some.4. Diet composition was significantly correlated with ant substrate preparation behaviours before adding forage to the fungus garden, indicating that diet composition and farming practices have co‐evolved. Neither diet nor preparation behaviours changed when a clade within the paleoattine genusApterostigmashifted from rearing leucocoprinous fungi to cultivating pterulaceous fungi, but the evolutionary derived transition to yeast growing in theCyphomyrmex rimosusgroup, which relies almost exclusively on nectar and insect frass, was associated with specific changes in diet composition.5. The co‐evolutionary transitions in diet composition across the genera of attine ants indicate that fungus‐farming insect societies have the possibility to obtain more optimal fungal crops via artificial selection, analogous to documented practice in human subsistence farming.

What Makes Tight Glycemic Control Tight? The Impact of Variability and Nutrition in Two Clinical Studies

Tight glycemic control (TGC) remains controversial while successful, consistent, and effective protocols remain elusive. This research analyzes data from two TGC trials for root causes of the differences achieved in control and thus potentially in glycemic and other outcomes. The goal is to uncover aspects of successful TGC and delineate the impact of differences in cohorts. A retrospective analysis was conducted using records from a 211-patient subset of the GluControl trial taken in Liege, Belgium, and 393 patients from Specialized Relative Insulin Nutrition Titration (SPRINT) in New Zealand. Specialized Relative Insulin Nutrition Titration targeted 4.0-6.0 mmol/liter, similar to the GluControl A (N = 142) target of 4.4-6.1 mmol/liter. The GluControl B (N = 69) target was 7.8-10.0 mmol/liter. Cohorts were matched by Acute Physiology and Chronic Health Evaluation II score and percentage males (p > .35); however, the GluControl cohort was slightly older (p = .011). Overall cohort and per-patient comparisons (median, interquartile range) are shown for (a) glycemic levels achieved, (b) nutrition from carbohydrate (all sources), and (c) insulin dosing for this analysis. Intra- and interpatient variability were examined using clinically validated model-based insulin sensitivity metric and its hour-to-hour variation. Cohort blood glucose were as follows: SPRINT, 5.7 (5.0-6.6) mmol/liter; GluControl A, 6.3 (5.3-7.6) mmol/liter; and GluControl B, 8.2 (6.9-9.4) mmol/liter. Insulin dosing was 3.0 (1.0-3.0), 1.5 (0.5-3), and 0.7 (0.0-1.7) U/h, respectively. Nutrition from carbohydrate (all sources) was 435.5 (259.2-539.1), 311.0 (0.0-933.1), and 622.1 (103.7-1036.8) kcal/day, respectively. Median per-patient results for blood glucose were 5.8 (5.3-6.4), 6.4 (5.9-6.9), and 8.3 (7.6-8.8) mmol/liter. Insulin doses were 3.0 (2.0-3.0), 1.5 (0.8-2.0), and 0.5 (0.0-1.0) U/h. Carbohydrate administration was 383.6 (207.4-497.7), 103.7 (0.0-829.4), and 207.4 (0.0-725.8) kcal/day. Overall, SPRINT gave approximately 2x more insulin with a 3-4x narrower, but generally non-zero, range of nutritional input to achieve equally TGC with less hypoglycemia. Specialized Relative Insulin Nutrition Titration had much less hypoglycemia (<2.2 mmol/liter), with 2% of patients, compared to GluControl A (7.7%) and GluControl B (2.9%), indicating much lower variability, with similar results for glucose levels <3.0 mmol/liter. Specialized Relative Insulin Nutrition Titration also had less hyperglycemia (>8.0 mmol/liter) than groups A and B. GluControl patients (A+B) had a approximately 2x wider range of insulin sensitivity than SPRINT. Hour-to-hour variation was similar. Hence GluControl had greater interpatient variability but similar intrapatient variability. Protocols that dose insulin blind to carbohydrate administration can suffer greater outcome glycemic variability, even if average cohort glycemic targets are met. While the cohorts varied significantly in model-assessed insulin resistance, their variability was similar. Such significant intra- and interpatient variability is a further significant cause and marker of glycemic variability in TGC. The results strongly recommended that TGC protocols be explicitly designed to account for significant intra- and interpatient variability in insulin resistance, as well as specifying or having knowledge of carbohydrate administration to minimize variability in glycemic outcomes across diverse cohorts and/or centers.

A multidisciplinary study of the Cape Peloro brackish area (Messina, Italy): characterisation of trophic conditions, microbial abundances and activities

AbstractIn the framework of the VECTOR DIVCOST Project, a 2‐year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH4, NO2, NO3, PO4]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.

A Responsive Feeding Intervention Increases Children’s Self-Feeding and Maternal Responsiveness but Not Weight Gain ,

Responsive complementary feeding, whereby the mother feeds her child in response to child cues and psychomotor abilities, is low in some countries and likely contributes to malnutrition. Interventions are needed to evaluate whether promoting responsive feeding would add any benefit. Using a cluster-randomized field trial, we evaluated a 6-session educational program that emphasized the practice of child self-feeding and maternal responsiveness. A total of 108 mothers and their 8- to 20-mo-old children in 19 clusters were randomly assigned to the intervention group and 95 in 18 clusters were assigned to the informational control group. Outcomes were assessed at pretest, postintervention, and follow-up. Research assistants, who were unaware of group assignment, observed and coded mother and child midday meal behaviors. At follow-up, the percent of self-fed mouthfuls was 47.8 ± 42.4 (mean ± SD) in the responsive feeding group children compared with 32.2 ± 41.0 in the controls (P = 0.01); likewise, the number of responsive verbalizations was 6.55 ± 5.9 in the responsive feeding mothers and 4.62 ± 4.5 in controls (P = 0.01). Intervention mothers recalled more messages. Mouthfuls of food eaten by children and weight were equivalent in the 2 groups. Lack of change in foods eaten and small quantities may explain the similarly low levels of weight gain. These results provide evidence that self-feeding and maternal verbal responsiveness, two developmentally important behaviors, can be increased by targeting specific behaviors with appropriate behavior change strategies of modeling and coached practice. Weight gain may require more nutritional input, especially in areas of high food insecurity.

The effect of the introduction of Nile tilapia (Oreochromis niloticus, L.) on small indigenous fish species (mola, Amblypharyngodon mola, Hamilton; chela, Chela cachius, Hamilton; punti, Puntius sophore, Hamilton)

This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m2) to assess the impact of mixed-sex or all-male Nile tilapia (Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola (Amblypharyngodon mola), chela (Chela cachius) and punti (Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m−2 of water surface area in the mixed-sex and all-male tilapia treatments and 0.42 fish m−2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed-sex tilapia with SIS, mono-sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21-month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m2) in the mixed-sex treatment compared with mola (221 ± 22/100 m2), chela (94 ± 8/100 m2) and punti (100 ± 7/100 m2). The number of mola was higher (399 ± 33/100 m2) in the all-male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed-sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS.

The Ecdysone receptor controls the post-critical weight switch to nutrition-independent differentiation inDrosophilawing imaginal discs

In holometabolous insects, a species-specific size, known as critical weight, needs to be reached for metamorphosis to be initiated in the absence of further nutritional input. Previously, we found that reaching critical weight depends on the insulin-dependent growth of the prothoracic glands (PGs) in Drosophila larvae. Because the PGs produce the molting hormone ecdysone, we hypothesized that ecdysone signaling switches the larva to a nutrition-independent mode of development post-critical weight. Wing discs from pre-critical weight larvae [5 hours after third instar ecdysis (AL3E)] fed on sucrose alone showed suppressed Wingless (WG), Cut (CT) and Senseless (SENS) expression. Post-critical weight, a sucrose-only diet no longer suppressed the expression of these proteins. Feeding larvae that exhibit enhanced insulin signaling in their PGs at 5 hours AL3E on sucrose alone produced wing discs with precocious WG, CT and SENS expression. In addition, knocking down the Ecdysone receptor (EcR) selectively in the discs also promoted premature WG, CUT and SENS expression in the wing discs of sucrose-fed pre-critical weight larvae. EcR is involved in gene activation when ecdysone is present, and gene repression in its absence. Thus, knocking down EcR derepresses genes that are normally repressed by unliganded EcR, thereby allowing wing patterning to progress. In addition, knocking down EcR in the wing discs caused precocious expression of the ecdysone-responsive gene broad. These results suggest that post-critical weight, EcR signaling switches wing discs to a nutrition-independent mode of development via derepression.

Postprandial changes in plasma growth hormone, insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins in coho salmon fasted for varying periods

We examined postprandial changes in circulating growth hormone (GH), insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins (IGFBPs) in yearling coho salmon under different feeding regimes. Fish were initially fasted for 1 day, 1 wk, or 3 wk. Fasted fish were then fed, and blood was collected at 4-h intervals over 26 h. After the various periods of fasting, basal levels of insulin were relatively constant, whereas those of IGF-I, IGFBPs and GH changed in proportion to the duration of the fast. A single meal caused a rapid, large increase in the circulating insulin levels, but the degree of the increase was influenced by the fasting period. IGF-I showed a moderate increase 2 h after the meal but only in the regularly fed fish. Plasma levels of 41-kDa IGFBP were increased in all groups within 6 h after the single meal. The fasting period did not influence the response of 41-kDa IGFBP to the meal. IGFBP-1 and GH decreased after the meal to the same extent among groups regardless of the fasting period. The present study shows that insulin and IGF-I respond differently to long (weeks)- and short (hours)-term nutritional changes in salmon; insulin maintains its basal level but changes acutely in response to food intake, whereas IGF-I adjusts its basal levels to the long-term nutritional status and is less responsive to acute nutritional input. IGFBPs maintain their sensitivity to food intake, even after prolonged fasting, suggesting their critical role in the nutritional regulation of salmon growth.

Microevolution of neuroendocrine mechanisms regulating reproductive timing in Peromyscus leucopus

A key question in the evolution of life history and in evolutionary physiology asks how reproductive and other life-history traits evolve. Genetic variation in reproductive control systems may exist in many elements of the complex inputs that can affect the hypothalamic-pituitary-gonadal (HPG) or reproductive axis. Such variation could include numbers and other traits of secretory cells, the amount and pattern of chemical message released, transport and clearance mechanisms, and the number and other traits of receptor cells. Selection lines created from a natural population of white-footed mice (Peromyscus leucopus) that contains substantial genetic variation in reproductive inhibition in response to short winter daylength (SD) have been used to examine neuroendocrine variation in reproductive timing. We hypothesized that natural genetic variation would be most likely to occur in the inputs to GnRH neurons and/or in GnRH neurons themselves, but not in elements of the photoperiodic pathway that would have pleiotropic effects on nonreproductive functions as well as on reproductive functions. Significant genetic variation has been found in the GnRH neuronal system. The number of GnRH neurons immunoreactive to an antibody to mature GnRH peptide under conditions maximizing detection of stained neurons was significantly heritable in an unselected control (C) line. Furthermore, a selection line that suppresses reproduction in SD (photoperiod responsive, R) had fewer IR-GnRH neurons than a selection line that maintains reproduction in SD (photoperiod nonresponsive, NR). This supports the hypothesis that genetic variation in characteristics of GnRH neurons themselves may be responsible for the observed phenotypic variation in reproduction in SD. The R and NR lines differ genetically in food intake and iodo-melatonin receptor binding, as well as in other characteristics. The latter findings are consistent with the hypothesis that genetic variation occurs in the nutritional and hormonal inputs to GnRH neurons. Genetic variation also exists in the phenotypic plasticity of responses to two combinations of treatments, (1) food and photoperiod, and (2) photoperiod and age, indicating genetic variation in individual norms of reaction within this population. Overall, the apparent multiple sources of genetic variation within this population suggest that there may be multiple alternative combinations of alleles for both the R and NR phenotypes. If that interpretation is correct, we suggest that this offers some support for the evolutionary "potential" hypothesis and is inconsistent with the evolutionary "constraint" and "symmorphosis" hypotheses for the evolution of complex neuroendocrine pathways.

Biomass and Nutrient Accumulation of Green Manuring Legumes Terminated at Different Growth Stages

A field study was conducted at the experimental site of the Assosa Research Center, western Ethiopia, with the objective of generating information about the biomass and nutrient accumulation of four green manuring (GM) legume crops at different growth stages. Accordingly, factorial combinations of four legume crops [cowpea ( Vigna unguiculata ), soybean ( Glycine max ), and two common bean verities (Black Dessie and Awash Melka) ( Phaseolus vulgaris )] and three growth stages of termination (mid-vegetative, mid-flowering and pod-setting) treatments laid in a randomized complete block design were used. Significant species by growth stage treatment interaction (P in Awash Melka variety were observed with a delay in termination times. In addition to the species variability in total DM production, highly significant effect of growth stage at termination was also observed, and a rise in overall DM production was recorded with the development of GM crops. Cowpea recorded the highest per plant number (5.8) and fresh mass of total (0.4 gm) and effective (0.21 gm) nodules compared to the rest, particularly at the mid-flowering stage of growth. According to the results of this study, nutrient (particularly N and K) concentrations of shoot tissue showed a declining trend with increasing plant age. After considering the species and growth stage effects on the nutritional input or contribution of GM, it was discovered that cowpea and midflowering stage of growth outweighed the rest. Keywords : Concentration; Nodules; Dry Matter; Input

Soil exchangeable cations, sugarcane production and nutrient uptake after wastewater irrigation

Wastewater irrigation may benefit agricultural crops with water and essential nutrients (mainly nitrogen), also affecting soil chemistry. The effects of effluent irrigation on yield, stalk nutrient uptake and on soil chemistry over 16 months were studied in a sugarcane (Saccharum spp.) crop growing on an Oxisol in Lins, State of São Paulo, Brazil. Irrigated plots received 50% of the recommended mineral-N fertilization and 100, 125, 150 or 200% of the crop water demand, while control plots received neither additional N nor water. The high sodium content of effluent resulted in Na inputs as high as 6.2 t ha-1, along with 1497 kg N ha-1 and 628 kg K ha-1. All the effluent plots except the T125 treatment had higher yields (up to 247 t ha-1) than the control (153 t ha-1). Significant amounts of N (up to 597 kg ha-1) and K (up to 546 kg ha-1) were exported by the plant harvest. Additions of nutrients and Na via irrigation were not compensated by stalk growth, causing a low recovery of N, P, Ca, Na, and showing the relative over N fertilization of the crop. Changes in soil pH, H + Al, Ca, Mg and K were small, whereas Na accumulated over time with irrigation. The treated wastewater irrigation is expected to gain increased importance, requiring careful considerations involving the adequate balance between nutritional inputs via irrigation and optimal plant productivity requirements.

Distribution of moon jellyfish Aurelia aurita in relation to summer hypoxia in Hiroshima Bay, Seto Inland Sea

Biological and physical surveys were conducted in order to investigate the relationship between environmental conditions and the distribution of moon jellyfish Aurelia aurita in Hiroshima Bay, western Seto Inland Sea, Japan. Moon jellyfish and ichthyoplankton were collected at 13 stations in Hiroshima Bay during monthly surveys from July to September in 2006 and 2007. Surface temperature in 2006 was significantly lower during the August and September cruises and surface salinity was lower during all cruises than in 2007. Moon jellyfish was the most dominant gelatinous plankton collected, accounting for 89.7% in wet weight. Mean moon jellyfish abundance in 2006 was higher than that in 2007 from July through September, with significant inter-year differences for July and September. Variability in precipitation and nutritional input from the Ohta River, northernmost part of Hiroshima Bay, were suggested as possible factors affecting the inter-annual variability in moon jellyfish abundance in the coastal areas of northern Hiroshima Bay. Moon jellyfish were more abundant in the coastal areas of northern Hiroshima Bay, where the dissolved oxygen (DO) concentration was lower, while low in the central part of the bay. Japanese anchovy Engraulis japonicus eggs were most dominant (58.1% in number) among the ichthyoplankton and were abundant in the central area of Hiroshima Bay. Explanatory analysis was conducted to detect possible effects of environmental conditions on the abundance of moon jellyfish and Japanese anchovy eggs during the summer months in Hiroshima Bay. Of the environmental conditions tested (temperature, salinity and DO of surface and bottom layers at each sampling station), bottom DO had the most significant effect on the moon jellyfish abundance: there was a negative correlation between the bottom DO and the moon jellyfish abundance in Hiroshima Bay during summer.

Improving nutritional status through behavioural change: lessons from Madagascar

The authors provide evidence for intermediate and long-term effects of a large scale intervention that focuses on quality of nutritional and child-care inputs during the early stages of life. Their empirical strategy uses a combination of difference-in-difference and weighting estimators in a longitudinal survey spanning ten years to estimate the effect of the availability of the programme at the community level on nutritional outcomes. They also provide indirect evidence to support their main identification assumption using falsification tests. They find that the programme helped 0–5 year old children in the participating communities to bridge their gap in weight-for-age z-score and the incidence of underweight. The programme also had significant effects in protecting long-term nutritional outcomes (height-for-age z-scores and incidence of stunting). Importantly, the effect of the programme exhibits substantial heterogeneity: gains in nutritional outcomes are larger for more educated mothers and for villages with better infrastructure. The results are suggestive of important complementarities between child-care, maternal education and community infrastructure.