Compensatory Feeding Research Articles

Ileal transposition: A non-restrictive bariatric surgical procedure that reduces body fat and increases ingestion-related energy expenditure

BackgroundIleal Transposition (IT) was developed as a model to study body weight reduction without the restrictive or malabsorptive aspects of other bariatric surgeries, but the exact mechanisms of the alterations in body weight after IT are not completely understood. ObjectiveTo provide a detailed description of the surgical procedure of IT, and describe its effect on energy balance parameters. MethodsAdult male Lewis rats underwent either IT (IT+) or sham (IT-) surgery. Following surgery body weight and energy intake were monitored. After attaining weight stability (> 30 days), energy expenditure and its components were assessed using indirect calorimetry at a day of fasting, limited intake, and ad libitum intake. At the end of the study body composition analysis was performed. ResultsIT+ resulted in transiently reduced energy intake, increased ingestion-related energy expenditure (IEE) and decreased body and adipose tissue weight when compared to IT-. At weight stability, neither energy budget (i.e., energy intake - energy expenditure), nor energy efficiency was different in IT+ rats compared to IT-. ConclusionOur data show that the primary cause of weight reduction following IT+ is a transient reduction in energy intake. If the increased IEE is related to a higher level of satiety, compensatory feeding to bridge body weight difference between IT+ and IT- rats is less likely to occur.

Stage specific feeding attributes and mobilization of nutrients in Mexican beetle, Zygogramma bicolorata Pallister on Parthenium hysterophorus L.

Abstract Parthenium hysterophorus L. (Asteraceae) is a toxic weed of agricultural farms, pastures and wastelands with a pan-tropical distribution. The weed causes a reduction in crop production of agricultural fields and severe health problems in humans. The Mexican beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is among the most promising candidates for the weed biocontrol. However, no previous study has evaluated assimilation of nutrients in this beetle. In the present study, feeding attributes and assimilation of nutrients by larvae of Z. bicolorata were assessed on the weed. Results revealed that the first larval instars of Z. bicolorata exhibited lowest consumption rates, and accumulated minimum concentrations of glucose, proteins and triglycerides in their body. They showed compensatory feeding, and displayed highest food utilization efficiencies and developmental rates. In contrast, the fourth larval instars exhibited higher food consumption rates and conversion efficiencies, but displayed lowest developmental rates. Accumulation of food reserves was also recorded maximum for the fourth larval instars. Overall, the findings may aid current mass-rearing efforts for Z. bicolorata in laboratories, but field trials are still needed to strengthen the present findings.

The effect of alternative feeding strategies for broiler breeder pullets: 2. Welfare and performance during lay

ABSTRACTFeeding broiler breeders to satiety has negative consequences on their health and reproduction. Alternative feeding strategies during rearing can improve welfare, although their implications during lay are not well understood. The objective was to examine the effect of rearing feeding treatments on the reproductive performance and feeding behavior of broiler breeders under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens under 1 of 4 isocaloric treatments: 1) daily control diet; 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days, 3 non-consecutive off-feed days per week); and 4) graduated control diet. Feeding frequency of the graduated treatment varied with age and finished on a daily basis. At 23 wk of age, group sizes were adjusted to 40 hens, and 5 mature Yield Plus Males roosters were introduced to each pen. Pens were under the same daily feeding management and same diet during lay. The performance of broiler breeders (growth rate, body weight uniformity, and reproductive performance) was determined until 64 wk of age. At the end of lay, feeding motivation was examined with a feed intake test and a compensatory feeding test. Data were analyzed using linear mixed regression models, with pen nested in the models and age as a repeated measure. The laying rate of hens reared on the graduated treatment decreased slower compared to control hens, resulting in a higher cumulative egg production (178.2 ± 3.8 eggs/hen) than control hens (165.2 ± 3.8 eggs/hen, P < 0.01) by 64 wk of age. Hens reared on non-daily feeding treatments laid lighter eggs with relatively heavier yolks and had higher feed intake at the end of lay than hens fed daily during rearing (P = 0.02). In conclusion, rearing feeding treatments impacted the growth rate and body weight uniformity during lay, feeding motivation at the end of lay, and the laying rate and hatchability depending on hens’ age.

Life on the edge: Compensatory growth and feeding rates at environmental extremes mediates potential ecosystem engineering by an invasive bivalve

Invasive non-native species (INNS) with marine or brackish origins have become increasingly common occupying freshwater habitats. The transition of INNS from marine or brackish water into physiologically stressful freshwater environments may be facilitated by compensatory growth and elevated feeding rates. In this study, we investigate the capacity of the Gulf wedge clam (Rangia cuneata), a brackish NNS that is spreading quickly across European waterways, to survive in freshwater conditions and consider its resultant impacts as an ecosystem engineer. To investigate the performance of R. cuneata under freshwater conditions, we compared the population structure, the physiological condition, and the growth of R. cuneata collected from its distributional limits in Great Britain. Feeding rate of R. cuneata was quantified by conducting a reciprocal transfer experiment with a two-way factorial design on individuals obtained from the freshwater and saline extremes. R. cuneata density was almost 10-fold higher at its most saline distributional limit (213 individual m−2, 3.1‰) compared to its most freshwater limit (22 individuals m−2, 1.2‰). The impaired physiological condition (18.7% lower relative soft tissue mass and 26.4% lower shell mass) and the lack of juvenile individuals also suggests that the R. cuneata inhabiting the freshwater extreme may not be able to maintain a persistent population over the long term. Although R. cuneata at its freshwater extreme were under stress, the per capita impacts caused by these individuals were not weakened at the suboptimal conditions, evidenced by their elevated growth and over four times as high relative clearance rate (0.28 L−1 g−1 h−1) compared to those from the saline limit (0.06 L−1 g−1 h−1). This study demonstrates that under suboptimal conditions, the physiological responses of INNS may result in elevated per capita effects which may lead to unexpected or under-estimated impacts on recipient ecosystems.

Salt has contrasting effects on the digestive processing of dilute nectar by two Neotropical nectarivorous bats

Nectarivorous vertebrates might include sugar-dilute nectar in their diet and they are expected to undergo compensatory feeding. However, physiological constraints might limit the intake of sugar-dilute nectar, affecting energy budgets. Among other physiological processes, the limiting role of osmoregulation is supported by enhanced intake rate of dilute sugar solutions by avian nectarivores when salt is added. We tested if the Greater Antillean Long-tongued bat (Monophyllus redmani) and the Brown flower bat (Erophylla sezekorni) compensated energy intake when fed dilute-sugar solutions (2.5 and 5% sucrose), and if salt content (11, 20 and 40 mM NaCl l−1) modulated the intake rate of these solutions. Both species were unable to compensate intake of solutions with varying sugar densities, and energy intake on the 2.5 and 5% diets was lower than on the most concentrated diets (10, 20 and 30% sucrose). Both species responded differently to the addition of salt. Salt addition did not affect the intake of 2.5% sugar solutions by the Greater Antillean Long-tongued bat, and it decreased the intake of 5% sugar solutions. In contrast, the Brown flower bat increased the intake of 2.5 and 5% sugar solutions when salt was added. Intake responses to varying sugar densities of our two focal species and that of other bat species previously studied indicate that they are not uniform and that they might be modulated by digestive and osmoregulatory physiological traits.

The nutritional landscape of host plants for a specialist insect herbivore.

Nutrition has far‐reaching effects on both the ecology and evolution of species. A substantial body of work has examined the role of host plant quality on insect herbivores, with a particular focus on specialist–generalist dynamics, the interaction of growth and other physiological attributes on fitness and tritrophic effects. Measures of plant quality usually involve one or two axes of nutritional space: typically secondary metabolites or elemental proxies (N and C) of protein and carbohydrates, respectively.Here, we describe the nutrient space of seven host plants of the specialist insect herbivore, Manduca sexta, using an approach that measures physiologically relevant sources of nutrition, soluble protein and digestible carbohydrates. We show that plant species differ markedly in their nutrient content, offering developing insect herbivores a range of available nutrient spaces that also depend on the age of the leaves being consumed.The majority of host‐plant species produce diets that are suboptimal to the herbivore, likely resulting in varying levels of compensatory feeding for M. sexta to reach target levels of protein to ensure successful growth and development. Low‐quality diets can also impact immune function leading to complex patterns of optimization of plant resources that maximizes both growth and the ability to defend from parasitoids and pathogens. This study is the first to quantify the nutrient space of a suite of host plants used by an insect herbivore using physiologically relevant measures of nutrition.

Compensatory Foraging in Stoichiometric Producer-Grazer Models.

Nutritional constraints are common as food resources are rarely optimally suited for grazing species. Elemental mismatches between trophic levels can influence population growth and foraging behaviors. Grazing species, such as Daphnia, utilize optimal foraging techniques, such as compensatory feeding. Here, we develop two stoichiometric producer-grazer models, a base model that incorporates a fixed energetic foraging cost and an optimal foraging model where energetic foraging costs depend on food nutritional content. A variable energetic foraging cost results in cell quota-dependent predation behaviors. Analyzing and comparing these two models allows us to investigate the potential benefits of stoichiometric compensatory foraging behaviors on grazer populations. Optimal foraging strategies depend on environmental conditions, such as light and nutrient availability. In low-light conditions, fixed energetic foraging appears optimal regardless of the nutrient loads. However, in higher light conditions and intermediate nutrient loads, grazers utilizing compensatory foraging strategies gain an advantage. Overall, grazers can benefit from compensatory feeding behaviors when the food nutrient content of their prey becomes low or high.

Age, mating status and sex influence food consumption and utilization efficiency of Parthenium beetle, Zygogramma bicolorata Pallister

A study was designed to evaluate the combined effects of age, mating status and sex on the feeding attributes of the Parthenium beetle, Zygogramma bicolorata Pallister when fed on Parthenium hysterophorus L., a serious weed of wastelands, pastures and agricultural fields. Newly emerged adult beetles were placed in two groups. Adults of the first group were kept unmated and their daily feeding and growth attributes were assessed for the following 20 days. By comparison, males and females of the second group were allowed to mate on the 11th day (attainment of sexual maturity) and mating pairs were kept individually to assess their daily feeding and growth attributes for the following 10 days. Results revealed higher consumption and growth rates of Z. bicolorata females than males. In contrast, males exhibited higher food conversion efficiencies than the females. However, food consumption and growth rates of unmated adults were higher than mated adults. Agebased regression graphs revealed decreased consumption rates, conversion efficiencies and growth rates of Z. bicolorata adults with increase in age. However, the mean body biomass of adults increased with increasing age. This further suggested compensatory feeding in Z. bicolorata adults as they age. The present findings may be helpful to mass-multiply Z. bicolorata in laboratories for the biocontrol of Parthenium weed in agricultural farms on the Indian subcontinent.

The sicker the better: nematode-infected passalus beetles provide enhanced ecosystem services.

There is growing appreciation for the role that parasites have in ecosystems and food webs, though the possibility that they could improve an ecosystem service has never been considered. In forest ecosystems, fallen trees naturally decay over time and slowly return their nutrients to the soil. Beetles in the family Passalidae play a key role by excavating tunnels and consuming wood from these logs, thereby breaking down the wood into smaller debris. In the eastern United States, the horned passalus ( Odontotaenius disjunctus) is host to a naturally occurring nematode, Chondronema passali, which appears to cause little harm to the beetles. We suspected this was due to compensatory food consumption by parasitized individuals, which we tested here. We collected and housed 113 adult beetles in individual containers with wood for three months, then determined the amount of wood each beetle had processed into fine debris and frass. We then assessed beetles for C. passali and compared wood processing rates between parasitized and non-parasitized groups. Results showed the average daily processing rate of parasitized beetles ([Formula: see text] = 0.77 g d-1) was 15% greater than that of unparasitized ones ([Formula: see text] = 0.67 g d-1). Parasitized beetles were 6% larger, and this may explain some of this pattern, though the effect of parasitism was still significant in our analysis. By extrapolating the daily rates, we estimate that 10 adult beetles without nematodes would break down approximately 2.4 kg of wood in a single year, while a group of 10 parasitized beetles would break down 2.8 kg. While our data are consistent with the idea of compensatory feeding, because these results are based on natural infections, we cannot rule out the possibility that beetles with heightened wood consumption are simply more likely to acquire the parasite. At an ecosystem level, it may not matter which is the case; parasitized beetles provide a more effective ecosystem service.

Macrophyte‐specific effects on epiphyton quality and quantity and resulting effects on grazing macroinvertebrates

Abstract Aquatic macrophytes can have a significant impact on their associated community of epiphytic algae and bacteria through the provisioning of structural habitat complexity through different growth forms, the exudation of nutrients and the release of allelochemicals. In turn, this effect on epiphytic biofilm biomass and nutrient content has a potential effect on the macroinvertebrates that depend on epiphyton as a food source. We studied the effect of living macrophytes and their growth form on biofilm development in a semi‐controlled replicated microcosm experiment. Conditions of a nutrient‐poor water layer and nutrient‐rich sediment were created to study the effects of nutrient exudation by living macrophytes. We compared biofilm quantity and quality on structurally simple (Vallisneria spiralis) versus complex (Egeria densa) living plants and artificial analogues. Subsequently, the biofilm that had developed on the plants was fed, in a laboratory growth experiment, to two species of macroinvertebrate grazers (the snail Haitia acuta and the mayfly nymph Cloeon dipterum). This enabled us to assess if and how the macrophyte‐induced effects on the epiphyton can influence macroinvertebrate grazers. Living macrophytes were found to have a significant effect on epiphytic algal cover, which was mostly expressed by a lower cover on living macrophytes compared to their artificial analogues. Additionally, epiphyton cover on artificial macrophytes was found to be higher on complex structures compared to simple ones, yet this was not observed on living macrophytes. Plant specific traits, such as the release of allelopathic substances, competition for nutrients and DIC, and the amount of CaCO3 deposition on plant surfaces might explain these results. The density of epiphytic bacteria was found to be negatively correlated with biofilm Ca content from macrophytes in every treatment except living E. densa, which differed in leaf anatomy from the other plants by possessing polar leaves. Furthermore, biofilm on living macrophytes had lower C:N:P molar ratios compared to that on artificial plants, which is likely to be explained by nutrient exudation by the living plants. Although it was expected that a more nutritious biofilm would lead to increased grazer growth, this was observed only for H. acuta on E. densa. Because biofilm quantity was not a limiting factor, this lack of effect may be caused by compensatory feeding. It can be concluded that, depending on their traits, living macrophytes can have a positive effect on macroinvertebrate grazers by providing a large surface area for colonisation by epiphytic algae and bacteria, by improving biofilm stoichiometry and by stimulating bacterial growth.

Branched-Chain Amino Acids Have Equivalent Effects to Other Essential Amino Acids on Lifespan and Aging-Related Traits in Drosophila.

Branched-chain amino acids (BCAAs) have been suggested to be particularly potent activators of Target of Rapamycin (TOR) signaling. Moreover, increased circulating BCAAs are associated with higher risk of insulin resistance and diabetes in both mice and humans, and with increased mortality in mice. However, it remains unknown if BCAAs play a more prominent role in longevity than do other essential amino acids (EAAs). To test for a more prominent role of BCAAs in lifespan and related traits in Drosophila, we restricted either BCAAs or a control group of three other EAAs, threonine, histidine and lysine (THK). BCAA restriction induced compensatory feeding, lipid accumulation, stress resistance and amelioration of age-related gut pathology. It also extended lifespan in a dietary-nitrogen-dependent manner. Importantly, the control restriction of THK had similar effects on these phenotypes. Our control diet was designed to have every EAA equally limiting for growth and reproduction, and our findings therefore suggest that the level of the most limiting EAAs in the diet, rather than the specific EAAs that are limiting, determines the response of these phenotypes to EAA restriction.

Plant silicon effects on insect feeding dynamics are influenced by plant nitrogen availability

AbstractAlthough there is growing evidence that silicon (Si)‐based plant defenses effectively reduce both the palatability and digestibility of leaves, and thus impact nutrient assimilation by insect herbivores, much less is known about how this is affected by extrinsic and intrinsic factors. For example, do herbivores exhibit compensatory feeding on poor‐quality diets with Si or are Si defenses less effective in agroecosystems where high N availability increases plant quality? To investigate the interactive effects of N and Si on insect feeding, we conducted insect performance and compensatory feeding bioassays using maize, Zea mays L. (Poaceae), and the true armyworm, Pseudeletia unipuncta Haworth (Lepidoptera: Noctuidae). In the performance assay, the addition of Si alone resulted in increased larval mortality compared with the controls, likely because early instars with poorly developed mandibles could not feed effectively. However, larvae fed on plants treated with both Si and N survived better than on plants treated with Si only, although pupal mass did not differ between treatments. In our compensatory assay, Si addition reduced maize consumption, but increased both armyworm approximate digestibility and N assimilation efficiency, suggesting that enhanced post‐ingestion feeding physiology, rather than compensatory food intake, could have accounted for the lack of Si effects on pupal weight. Overall, our results demonstrate that, similar to other chemical and mechanical defenses, the effectiveness of plant Si defense is influenced by plant nutrient status and consumer compensatory ability.

Oak genotype and phenolic compounds differently affect the performance of two insect herbivores with contrasting diet breadth.

Research on plant-herbivore interactions has long recognized that plant genetic variation plays a central role in driving insect abundance and herbivory, as well as in determining plant defense. However, how plant genes influence herbivore feeding performances, and which plant defensive traits mediate these effects, remain poorly understood. Here we investigated the feeding performances of two insect leaf chewers with contrasting diet breadth (the generalist Lymantria dispar L. and the specialist Thaumetopoea processionea L.) on different genotypes of pedunculate oak (Quercus robur L.) and tested the role of leaf phenolics. We used leaves from four clones of 30 Q. robur full-sibs grown in a common garden to estimate the performance of both herbivores in laboratory feeding trials and to quantify the concentration of constitutive chemical defences (phenolic compounds). We found that tree genetics influenced leaf consumption by T. processionea but not by L. dispar. However genetic variation among trees did not explain growth rate variation in either herbivore nor in leaf phenolics. Interestingly, all phenolic compounds displayed a positive relationship with L. dispar growth rate, and leaf consumption by both herbivores displayed a positive relationship with the concentrations of condensed tannins, suggesting that highly defended leaves could induce a compensatory feeding response. While genetic variation in oaks did not explain herbivore growth rate, we found positive genetic correlations between the two herbivores for leaf consumption and digestion. Overall, we found that oak genotype and phenolic compounds partly and independently contribute to variability in herbivore performance. We challenged the current view of plant-insect interaction and provided little support to the idea that the effect of plant genotype on associated organisms is driven by plant defences. Together, our results point to the existence of genetically determined resistance traits in oaks whose effects differ between herbivores and motivate further research on mechanisms governing oak-herbivore interactions.

Household Food Security among Different Wealth Groups within Uyo Metropolis in Southern Nigeria

Studies done in various states in Nigeria have shown alarming rates of food insecurity among the population. The aim of this study was to determine the prevalence of household food insecurity among different wealth groups in Uyo metropolis, in southern Nigeria and to determine compensatory feeding patterns engaged in by studied food insecure households. This was a cross sectional descriptive study carried out among 249 households of different wealth groups based on the occupational status and educational attainment of the household heads. Data was collected using interviewer administered semi-structured questionnaire and analyzed using SPSS version 20 with a 0.05 level of significance. The prevalence of food insecurity among surveyed households was 89.9% with food insecure 26.5% (without hunger), 30.5% (moderate hunger) and 32.9% (severe hunger). Marital status, socioeconomic class, household size and household income all had statistically significant relationships with food security status (p7 suffered food insecurity with severe hunger. Regarding household income, 48.9% of households with income less than 50,000 naira per month, were food insecure with severe hunger (p<0.05). Coping strategies engaged in by food insecure households included borrowing money from friends, 33.7%, collecting food from friends 26.1% and sending children to work, 8.8%. There was high prevalence of food insecurity among studied households. It is recommended that better educational opportunities be made available to those of the low socioeconomic class, so as to ensure gainful employment. Minimum wage in Nigeria should be increased to ensure increased household income.

Effects of high and low C:P foods on the feeding of Daphnia pulex

The effects of food quality and food quantity on crustacean zooplankton’s feeding rate have been analyzed in the present study. In two experiments, we studied the clearance rates (CRs) of Daphnia pulex on different algal diets (Scenedesmus obliquus, nontoxic Microcystis sp. PCC7806 and Anabeana flos-aquae) varying in carbon to phosphorus (C:P) ratios and quantities (concentrations). In order to investigate the effects of different algal diets on the feeding of cladocerans, the mixture of S. obliquus, Microcystis sp. PCC7806 and A. flos-aquae was also fed to D. pulex during a 72-h period. Our results showed: (1) D. pulex had different clearance rates from the three mono-specific P-rich algal diets, while no significant difference among clearance rates was observed among the three mono-specific P-poor algal diets; (2) D. pulex increased its clearance rates when it fed on mono-specific P-poor S. obliquus and A. flos-aquae, while a P-poor mixture of M. aeruginosa and A. flos-aquae reduced the clearance rate; (3) A U-shaped quadratic function provided a good fit to the clearance rate and C:P ratios because the clearance rate of D. pulex in both low and high C:P categories were significantly higher than in the moderate C:P category (C:P value = 219). Our results demonstrated that filaments and C:P ratios of algae strongly influence the feeding of crustacean zooplankton. ‘Compensatory feeding’ occurred in the mono-specific, P-poor algal diets but not in the mixed diets. Moreover, the clearance rate of zooplankton was the lowest in the moderate P stoichiometric category. Our experiments suggest that the morphology and C:P ratios of algal diets have important effects on the feeding of Daphnia, and the P stoichiometric characteristics in mixed diets may play an important role in the feeding of large-sized cladocerans.

PSXVI-6 Diet deprivation followed by compensatory feeding of gestating gilts does not affect lactation performance.

PSXVI-6 Diet deprivation followed by compensatory feeding of gestating gilts does not affect lactation performance.

High nutrient availability leads to weaker top‐down control of stream periphyton: Compensatory feeding in Ancylus fluviatilis

Abstract Benthic algal biomass and distribution in freshwater ecosystems are determined by both nutrient availability (bottom‐up control) and grazing activity by herbivores (top‐down control). Fluctuations in algal nutrient ratios may cause grazers to optimise their food intake through behavioural strategies in order to maintain a constant soft body stoichiometry. Such linkages between nutrient availability and grazing control of algal biomass are as yet poorly understood. In this study, we tested whether the stream‐dwelling freshwater gastropod Ancylus fluviatilis would increase its food consumption rate with decreasing periphyton nutrient content, a behaviour known as compensatory feeding. We performed a fully factorial microcosm experiment in which two levels of periphyton phosphorus content (low versus high) were crossed with grazer presence/absence in 12 circular flumes. After 1 week of grazing, food consumption rates were measured by determining the periphyton difference between grazed and ungrazed flumes, and the periphyton biomass variability in every flume was described with a coefficient of variation. The food consumption rate of A. fluviatilis was significantly higher in the low phosphorus compared to the high phosphorus treatment, supporting the compensatory feeding hypothesis. As a result, in the presence of grazers, periphyton biomass was significantly lower under low phosphorus availability, while biomass was not affected by nutrient enrichment in the grazer‐free flumes. Despite the strong difference in periphyton phosphorus content, A. fluviatilis soft body stoichiometry did not differ between the two nutrient treatments, suggesting strong stoichiometric homeostasis. Furthermore, the distribution of algal biomass was significantly more heterogeneous in the grazed phosphorus‐poor than in the phosphorus‐rich periphyton. Our findings suggest that nutrient enrichment may lead to a weaker top‐down control of algal biomass in stream ecosystems and to reduced spatial heterogeneity of periphyton abundance.

Fasting and refeeding induce differential changes in hypothalamic mRNA abundance of appetite-associated factors in 7 day-old Japanese quail, Coturnix japonica

There is little information regarding effects of fasting on feeding behavior and hypothalamic physiology in young Japanese quail. The aim was thus to measure food intake and hypothalamic mRNA in response to fasting and refeeding. Five d-old quail ate little during the dark cycle. Food intake was greatest during the first 2 h of the light cycle. Six day-old quail fasted for 6 h ate the most during the first 15 min of refeeding. In 7 d-old quail, 3 h of fasting up-regulated hypothalamic neuropeptide Y (NPY), NPY receptor sub-type 2 (NPYR2), agouti-related peptide (AgRP), orexin receptor 2 (ORXR2), melanocortin receptors 3 and 4 (MC3R and MC4R, respectively), and neuropeptide S (NPS) and decreased corticotropin-releasing factor receptor sub-type 1 (CRFR1) mRNA. Quail fasted for 3 h and refed for 1 h had greater NPY, AgRP, POMC, and MC3R but less CRFR1 mRNA than fed quail. Quail fasted for 6 h expressed more NPY, NPYR1, NPYR2, and MC3R and less ORXR2, prolactin releasing peptide (PrRP), cocaine- and amphetamine-regulated transcript (CART), and calcitonin (CAL) mRNA than fed quail. Quail fasted for 6 h and refed for 1 h expressed more NPY, NPYR1, NPYR2, AgRP, MC3R, MC4R, and NPS and less galanin, ORXR2, PrRP, CART, and CAL mRNA than fed birds. Hence, fasting induced changes in hypothalamic mRNA, with the largest changes occurring in genes associated with NPY and melanocortin signaling. Most genes remained elevated or downregulated after refeeding, suggesting that there was a time lag for transcription to respond to compensatory feeding.

Insulin-Like Peptides Regulate Feeding Preference and Metabolism in Drosophila.

Fruit flies have eight identified Drosophila insulin-like peptides (DILPs) that are involved in the regulation of carbohydrate concentrations in hemolymph as well as in accumulation of storage metabolites. In the present study, we investigated diet-dependent roles of DILPs encoded by the genes dilp1–5, and dilp7 in the regulation of insect appetite, food choice, accumulation of triglycerides, glycogen, glucose, and trehalose in fruit fly bodies and carbohydrates in hemolymph. We have found that the wild type and the mutant lines demonstrate compensatory feeding for carbohydrates. However, mutants on dilp2,3, dilp3, dilp5, and dilp7 showed higher consumption of proteins on high yeast diets. To evaluate metabolic differences between studied lines on different diets we applied response surface methodology. High nutrient diets led to a moderate increase in concentration of glucose in hemolymph of the wild type flies. Mutations on dilp genes changed this pattern. We have revealed that the dilp2 mutation led to a drop in glycogen levels independently on diet, lack of dilp3 led to dramatic increase in circulating trehalose and glycogen levels, especially at low protein consumption. Lack of dilp5 led to decreased levels of glycogen and triglycerides on all diets, whereas knockout on dilp7 caused increase in glycogen levels and simultaneous decrease in triglyceride levels at low protein consumption. Fruit fly appetite was influenced by dilp3 and dilp7 genes. Our data contribute to the understanding of Drosophila as a model for further studies of metabolic diseases and may serve as a guide for uncovering the evolution of metabolic regulatory pathways.

Nutrient load and epiphytes are drivers of increased herbivory in seagrass communities

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 599:49-64 (2018) - DOI: https://doi.org/10.3354/meps12622 Nutrient load and epiphytes are drivers of increased herbivory in seagrass communities R. Jiménez-Ramos*, L. G. Egea, J. J. Vergara, F. G. Brun Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Puerto Real, 11510 Cádiz, Spain *Corresponding author: rocio.jimenez@uca.es ABSTRACT: Eutrophication is one of the major threats facing seagrasses, promoting effects in different compartments of the community (e.g. plants, epiphytes, fauna). In this study, we researched how in situ nutrient enrichment modified the consumption rates of Cymodocea nodosa plants during a period of 3 mo, by creating a set of mesocosm feeding choice experiments with the generalist herbivore Paracentrotus lividus. Nutrient enrichment intensified the consumption of C. nodosa leaves by increasing the palatability of their tissues at different levels. At a first level (i.e. the individual plant response), nutritional quality of the tissues increased (i.e. nitrogen content), while both biomechanical (i.e. absolute force-to-tear, FTA, and specific force-to-tear, FTS) and mechanical (i.e. fiber content) traits were reduced. At a second level, the presence of epiphytes coating the leaves increased their nutritional quality without actually increasing their biomechanical resistance, which rendered higher consumption rates. However, the presence of Ulva sp. (a highly palatable macrophyte) reduced the direct consumption of C. nodosa leaves, mainly when coated by epiphytes, a fact fully endorsed by the compensatory feeding theory. Therefore, the nutritional quality of the C. nodosa leaves is a key factor regulating their susceptibility to be consumed, although mechanical and biomechanical factors also gained importance when nutritional quality was low. In addition, the presence of other components of the community (epiphytes and macroalgae) may increase or reduce herbivore pressure, highlighting the complex nature of herbivore-plant interrelationships. KEY WORDS: Cymodocea nodosa · Eutrophication · Grazing · Herbivore · Macroalgae · Paracentrotus lividus · Plant-herbivore interactions · Sea urchin Full text in pdf format Supplementary material PreviousNextCite this article as: Jiménez-Ramos R, Egea LG, Vergara JJ, Brun FG (2018) Nutrient load and epiphytes are drivers of increased herbivory in seagrass communities. Mar Ecol Prog Ser 599:49-64. https://doi.org/10.3354/meps12622 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 599. Online publication date: July 12, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.