Rate Of Mass Gain Research Articles

Effect of impact angle on hot corrosion resistance of abrasive water jet peened Ti-6Al-4V alloy

The effect of peening angle (10° to 40°) on NaCl induced hot corrosion behavior of Ti-6Al-4V alloy was evaluated at 750 °C for 100 h. Peening at higher impact angles progressively increases the surface roughness, number of sub-grains, magnitude of compressive residual stresses and hardness of the alloy. During hot corrosion, the surfaces of Ti-6Al-4Al, irrespective of the peened condition, develops oxide scales that contain oxides of Ti, Al and V. Hot corrosion rate, measured in terms of rate of mass gain and the rate constant, Kp, was highest for the unpeened alloy but decreased for surfaces subjected to AWJ peening. Surfaces peened at increasing impact angles have smaller mass gain rate and the one peened at the impact angle of 30° exhibited the lowest corrosion rate and a lowest Kp of ~0.08 mg2/cm4/h. The surface peened at 40° is, however, not as corrosion resistant. The mechanism of corrosion was discussed in the context of corrosion products formed and the opposing influences of initial roughness and compressive residual stresses. While higher roughness promotes hot corrosion by facilitating sites for corrosive attack, higher compressive residual stresses retard the diffusion of corrosive species into the Ti-6Al-4V surface. Based on these discussions, the optimum impact angle for AWJ peening for imparting maximum hot corrosion resistance on Ti-6Al-4V was determined to be ~30°.

Analysis of bacterial community of Labidochromis caeruleus reared in RAS with various feeds

The electric yellow cichlid (Labidochromis caeruleus), renowned for its exceptional ornamental value, enjoys widespread popularity among aquarium enthusiasts and holds significant economic value in the market. This study employed high-throughput sequencing technology to analyze the microorganisms in the circulating water of the electric yellow cichlid cultivated with six different types of feeds. Statistical results showed that the compound feed group exhibited the highest specific growth and mass gain rates. In contrast, the water flea and brine shrimp groups showed lower rankings with significant differences. 51,084 to 64,626 effective sequences were obtained and clustered into 127 to 848 operational taxonomic units (OTUs). The research findings indicate a remarkable bacterial diversity in the breeding environment of electric yellow cichlids with higher levels in the water flea and brine shrimp groups, and the lowest level in the compound feed group; the dominant bacterial phyla in all six experimental groups include Proteobacteria, Actinobacteria, Parcubacteria, and Cyanobacteria; Comparative analysis using the COGs database revealed significant differences (P<0.05) in the metabolic pathways of 24 functional microbial genes among the experimental groups.

The influence of diet on gut microbiome and body mass dynamics in a capital-breeding migratory bird.

Gut-associated microbial communities are known to play a vital role in the health and fitness of their hosts. Though studies investigating the factors associated with among-individual variation in microbiome structure in wild animal species are increasing, knowledge of this variation at the individual level is scarce, despite the clear link between microbiome and nutritional status uncovered in humans and model organisms. Here, we combine detailed observational data on life history and foraging preference with 16S rRNA profiling of the faecal microbiome to investigate the relationship between diet, microbiome stability and rates of body mass gain in a migratory capital-breeding bird, the light-bellied Brent goose (Branta bernicla hrota). Our findings suggest that generalist feeders have microbiomes that are intermediate in diversity and composition between two foraging specialisms, and also show higher within-individual plasticity. We also suggest a link between foraging phenotype and the rates of mass gain during the spring staging of a capital breeder. This study offers rare insight into individual-level temporal dynamics of the gut microbiome of a wild host. Further work is needed to uncover the functional link between individual dietary choices, gut microbiome structure and stability, and the implications this has for the reproductive success of this capital breeder.

Firmicutes and Bacteroidetes contribute to mass gain variation in female obligate hibernators

Abstract Obtaining body condition is an important life history challenge that directly impacts individual fitness and is particularly important for hibernating animals, whose maintenance of adequate body fat and mass is essential for survival. It is well-documented that host-associated microorganisms play a vital role in animal physiology and behavior. Recent work demonstrates that gut microbes are associated with fat accumulation and obesity, particularly the phyla Firmicutes and Bacteroidetes. The focus of most microbiome studies has been on human health or involved lab-reared animals used as a model system. However, these microbes likely are important for individual fitness in wild populations and provide potential mechanistic insights into the adaptability and survival of wildlife. Here we tested whether symbiotic microorganisms within the phyla of Firmicutes and Bacteroidetes were associated with summer mass gain in an exceptionally well-studied wild population of yellow-bellied marmots (Marmota flaviventer) by analyzing 207 fecal samples collected over 5 summer active seasons. Results showed that marmots with higher mass gain rates had a greater relative abundance of Firmicutes. In contrast, a higher relative abundance of Bacteroidetes was associated with lower mass gain rates, but only for marmots living in harsher environments. Similar patterns were found at the family level where Ruminococcaceae, a member of Firmicutes, was associated with higher mass gain rates, and Muribaculaceae, a member of Bacteroidetes, was associated with lower mass gain rates in harsher environments. Although correlative, these results highlight the potential importance of symbiotic gut microbiota to mass gain in the wild—a trait associated with survival and fitness in many taxonomic groups.

Irruptive fall migrations are linked to elevated breeding abundance but are not associated with body condition or stopover duration in Northern Saw-whet Owls

Abstract Bird species that undertake irruptive migrations are good candidates for assessing density-dependent effects on stopover ecology because the number of birds using stopover sites varies considerably from year to year. Using morphometric data from a 9-year banding program and radiotelemetry (n = 25 females), we found that increases in the annual density of Northern Saw-whet Owls (NSWO; Aegolius acadicus) encountered at a fall stopover site in Nova Scotia, Canada, were not linked to female body condition or minimum stopover duration. Rather, most NSWO spent no more than 1 or 2 full days at the stopover site following radio-tagging and during their return visits to the site. Body condition indices were highest for NSWO captured near the end of the migration monitoring season, possibly reflecting birds that had recently established wintering ranges and were elevating energy stores. We used breeding abundance indices derived from Birds Canada’s Atlantic Nocturnal Owl Survey to help test the hypothesis that irruptive fall migrations in NSWO were driven by elevated breeding productivity and dispersal of immature birds (breeding success hypothesis). Indeed, irruptive fall migrations were characterized by elevated densities of immatures, but not adults, and mean breeding abundance indices for the Maritime provinces during years with irruptive migrations were higher than those for non-irruptive years. We hypothesize that prey abundance during years with irruptive migrations was sufficient to enable high breeding densities and minimize effects of elevated fall densities of NSWO on rates of mass gain and stopover duration.

Phase transformation and diffusion in high-temperature oxidation of FeCrNi medium entropy alloy

The oxidation of the FeCrNi medium entropy alloy is investigated from 700 to 1000 °C by combining experimental observations with density functional theory (DFT) calculations. The sole oxidation product formed is Cr2O3. At 900 °C, the layer exhibits desirable density and continuity, attributed to the rapid diffusion of Cr facilitated by the body-centered cubic phase transformation. There is a significant increase in mass gain rates at 1000 °C, accompanied by the formation of a discontinuous Cr2O3 layer and penetration of oxide. These observations emphasize the significant roles of phase structure in promoting the formation of protective oxide scales and influencing oxidation resistance.

Compact groups from semi-analytical models of galaxy formation – IV: Effect of group assembly on the evolution of their galaxies

ABSTRACT Using over 3000 compact groups (CGs) of galaxies extracted from mock catalogues built from semi-analytical models (SAMs) of galaxy formation, we study whether the CG assembly channel affects the z = 0 properties of galaxies and their evolution. The evolution of CG galaxy properties with time is a clear function of their stellar masses. For instance, high-stellar-mass CG galaxies have lived their last 8 Gyr with little cold gas content while maintaining their reservoir of hot gas, while low-mass CG galaxies still preserve some of their cold gas content at the present but they have completely drained their hot gas reservoir. Beyond that, we find that the evolution of CG galaxies is also a function of the assembly history of the CGs: with more extreme losses of gas content, faster mass gain rates for black holes and more marked suppression of star formation as a function of cosmic time as we go from recent to early CG assembly. Thus, CGs constitute another laboratory for galaxy assembly bias, as the later assembling groups have later star formation. Our results show that classifying CGs according to their assembly channel is a way of distinguishing different paths by which galaxies transform their properties throughout their history.

Nano-Curcumin/Chitosan Modulates Growth, Biochemical, Immune, and Antioxidative Profiles, and the Expression of Related Genes in Nile tilapia, Oreochromis niloticus

This study aimed to evaluate the effects of dietary supplementation with nano-curcumin (NCur) and a nano-curcumin/chitosan blend (NCur/Ch) on growth performance, digestibility, immune response, antioxidant status, intestinal morphometric characters, and gene regulation in Nile tilapia. Fish (n = 180, initial body weight = 12.0 ± 0.53 g) received supplementary NCur at rates of 0 (control), 0.00625, and 0.0125, and NCur/Ch at rates of 0.00625 + 0.5 g/kg diet for 4 weeks. Growth performance parameters (final weight and length, body mass gain, specific growth, and length gain rates) were markedly increased, and the feed conversion ratio was significantly decreased in the NCur- and NCur/Ch-supplemented groups. Digestive enzyme (amylase), immune response markers (immunoglobulin M, nitrous oxide, and lysozyme activity), plasma albumin, and total protein were increased significantly, mainly with a diet supplemented with 0.00625 g NCur/kg. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), glucose, and cortisol levels decreased in the supplemented groups compared to the control. Significantly increased glutathione peroxidase (GPx) and decreased malondialdehyde (MDA) levels were observed in the NCur/Ch group. Superoxide dismutase (SOD) activity was improved in the 0.0125 NCur group. Intestinal morphometric characters, including villus length, width, interspace, and goblet cell abundance, were increased to cope with improved growth performance and were associated with upregulation of insulin-like growth factor 1 (igf-1) and complement C-5 (cc5) compared to the control group. Therefore, NCur and an NCur/Ch blend could be supplemented in the Nile tilapia diets as a natural alternative to promote growth, digestion, immune status, liver function, antioxidant status, and related gene expression in O. niloticus.

Corrosion Risk to Metal-Based Artefacts in a Scientific and Technical Museum: An Assessment of Environmental and Exhibition Conditions.

Materials such as wood, textiles, or plastics that are part of the exhibition system in museums are known to emit pollutants such as organic acids. Scientific and technical objects that include these materials in their composition can themselves be a potential source of emissions, which, together with inappropriate humidity and temperature conditions, can lead to corrosion of the metallic parts. In this work, we have studied the corrosivity of different locations in two venues of the Spanish National Museum of Science and Technology (MUNCYT). Coupons of the most representative metals from the collection were placed in different showcases and rooms for 9 months. The corrosion of the coupons has been evaluated in terms of the rate of mass gain, colour changes and characterisation of the corrosion products. The results were correlated to the relative humidity and concentration of gaseous pollutants to determine which metals are most susceptible to corrosion. The results show that metal artefacts exposed in showcases have a higher risk of corrosion than those exposed directly in the room, and that some pollutants are emitted by the artefacts. The corrosivity of the museum environment is low for copper, brass, and aluminium in most locations; however, some placements present a higher aggressivity for steel and lead, due to the high humidity and the presence of organic acids.

Low-Molecular-Mass Fragments of Collagen Improve Parameters Related to Mass and Inflammation of the Adipose Tissue in the Obese Rat.

Despite clearly recognized links between increased body mass and increased risk for various pathological conditions, therapeutic options to treat obesity are still very limited. The aim of the present study is to explore the effect of low-molecular-mass collagen fragments obtained from the scales of Antarctic wild marine fish on rats' visceral and subcutaneous white adipose tissue in a high-calorie diet-induced obesity model. The study was conducted on outbred rats, which were divided into 3 experimental groups: (i) control, consuming standard food (3.81 kcal/g), (ii) obese group, consuming a high-calorie diet (5.35 kcal/g), and (iii) obese group, consuming a high-calorie diet (5.35 kcal/g) with intragastric administration of low-molecular-mass collagen fragments (at a dose 1 g/kg of body mass during 6 weeks). Low-molecular-mass collagen fragments were obtained by a procedure that included collagen extraction from fish scales and enzymatic hydrolysis with pepsin. Apart from hematoxylin and eosin staining, fibrosis level was assessed by histochemical Van Gieson's trichrome picrofuchsin staining, and mast cells were analysed by toluidine blue O staining. Group treated with low-molecular-mass fragments of collagen exhibited decreased rate of mass gain, relative mass, area occupied by collagen fibre of both visceral and subcutaneous adipose tissue, and cross-sectional area of both visceral and subcutaneous adipocytes. Treatment with low-molecular-mass fragments of collagen reduced the infiltration of immune cells, number of mast cells and their redistribution back to the septa. This was also accompanied by a decreased number of the crown-like structures formed by the immune cells, which are markers of chronic inflammation that accompanies obesity. This is the first study that reports the anti-obesity effect of low-molecular-mass fragments produced as a result of controlled hydrolysis of collagen from the scales of Antarctic wild marine fish in the in vivo model. Another novelty of this work is the observation that the tested collagen fragments not only reduce the body mass, but also improve the morphological and inflammatory parameters (decrease in the number of crown-like structures, immune cell infiltration, fibrosis and mast cells). Altogether, our work suggests that low-molecular-mass collagen fragments are a promising candidate for amelioration of some comorbidities linked to obesity.

One-degree resolution mascon solution over Antarctic derived from GRACE Level-2 data

The mass loss of the Antarctic Ice Sheet (AIS) is an important contributor to global sea-level rise in response to the warming ocean and atmospheric temperatures as well as the changes in current systems and precipitation patterns. In this study, a regional mascon method is developed to squeeze more mass change signals, in which the pseudo-observations of the geopotential are generated from the unfiltered GRACE Level-2 data whereas the regularization matrix is constructed with the prior information derived from filtered GRACE Level-2 data. A series of mascon solutions with 1°×1° equal-area resolution over AIS is derived from the updated Tongji-Grace2018 model spanning April 2002 to December 2016. Compared to the filtering results from P4M6 decorrelation and 100 km Gaussian filtering, our mascon solutions can effectively suppress the strips, improve the spatial resolution over AIS, and get a stronger signal with an improvement of 116.86% in the Antarctic Peninsula Ice Sheet (APIS), and more coincide with the features of glaciers and ice streams, such as the most striking ice mass loss in Totten, Getz, Thwaites and Pine Island, and the ice mass gain in Kamb Ice Stream. During the period from 2002 to 2016, the mass change rates from our mascon solution are −103.6 ± 5.6 Gt/yr, 63.0 ± 4.3 Gt/yr, −143.3 ± 4.9 Gt/yr and −23.29 ± 1.2 Gt/yr in AIS, East AIS, West AIS, and APIS, respectively. The mass change signals at the basin scale are with even more distinguishing features, with the highest mass gain rates of 18.03 ± 1.88 Gt/yr and 14.55 ± 0.60 Gt/yr at Basin 7 and Basin 18, and the highest mass loss rates of −58.57 ± 2.48 Gt/yr and −44.12 ± 2.27 Gt/yr at Basin 21 and Basin 22. Relative to the cumulated surface mass balance from the regional atmospheric climate model, the correlation coefficients of our mascon solutions are 0.91, 0.94, and 0.96 in East AIS, West AIS, and APIS.

Thermal analysis of the effects of cobalt additions on the high temperature expansion, melting and oxidation behaviors of nickel-based superalloys

ABSTRACT Cobalt is rarely present in nickel-based superalloys. When present, Co may produce a solid solution hardening effect on matrix or a stabilising effect for tantalum carbides if present. Co may also influence the general behaviour of Ni alloys at high temperature. In this work, the effects of Co on several high-temperature properties of a chromium-rich nickel-based alloy designed to be reinforced by TaC carbides are investigated. Different thermal analysis techniques are used: differential scanning calorimetry (DSC), thermo-mechanical analysis (TMA), and thermogravimetry (TG). Results show that the progressive addition of cobalt influences significantly the as–cast microstructure and the isothermal oxidation kinetics, but much less the refractoriness of the alloy and the thermal expansion behaviour. By adding Co, the interdendritic carbide population is made of more and more tantalum carbides, at the expense of chromium carbides. At the same time, the rate of mass gain due to oxidation increases.

Active season body mass patterns of little brown and northern myotis bats.

Animals are expected to adjust their behavioral patterns to improve fitness outcomes, such as fecundity or offspring survival. For long-lived hibernators, decisions made in each annual cycle may reflect considerations not just for concurrent survival and reproduction but also the pressure to maximize overwinter survival and future reproductive success. We examined how these elements manifest themselves in the body mass variation patterns of North American northern latitude temperate bats, whose size and roosting habits present considerable monitoring challenges. We characterized and compared the summer and fall mass variation patterns of little brown myotis (Myotis lucifugus) and northern myotis (M. septentrionalis) from a historic dataset. In summer, the estimated date of parturition was strongly associated with spring foraging conditions (low wind, low precipitation, and warm temperatures), and mass gain associated with female reproduction conferred considerable differentiation between the mass variation patterns of females and males. In fall, differences were most apparent among species, although adults exhibited a greater capacity for rapid mass gain than juveniles. These results demonstrate how reproductive constraints and interannual survival have important influences on the behavior of temperate bats. Future work should seek to quantify the fitness benefits of patterns identified in this study, such as the rate of prehibernation mass gain.

Effects of semi-constant temperature on embryonic and hatchling phenotypes of six-tubercled Amazon River turtles, Podocnemis sextuberculata

PurposeWe evaluated how constant incubation temperatures affect life-history traits pre-hatching and post-hatching of the six-tubercled Amazon River turtle, Podocnemis sextuberculata. MethodsWe incubated eggs from natural nests at ten semi-constant temperatures between 22.26 ± 1.01 °C and 37.37 ± 0.38°C (2013) and at six temperatures between 25.75 ± 0.22 °C and 36.17 ± 0.15°C (2016). In 2013, we raised hatchling for 90 days to evaluate effects of temperature on early hatchling growth. We evaluated maternal effects in 2016. ResultsP. sextuberculata displays temperature-dependent sex determination and produces males at colder and females at warmer temperatures (TSD Ia). The estimated pivotal temperature was 33.73 ± 0.15 °C and the transitional range of temperatures (TRT) 1.16 ± 0.59 °C. Semi-constant temperatures below 26 °C and above 38 °C were lethal. Intermediate temperatures (32.25 °C and 31.5 °C, respectively) were optimal for hatching success and produced larger hatchlings that grew slower early in life compared to colder or warmer conditions, which produced smaller hatchlings. Warmer incubation temperatures within the optimal range (28°C–37 °C) accelerated embryonic development. In contrast, comparisons of 30, 60 and 90 days-old suggests that warmer incubation temperatures reduced growth and mass gain rates post-hatching, such that incubation temperature effects on body size at emergence disappeared by 3 months of age. ConclusionsSix-tubercled Amazon River turtles showed the highest pivotal temperature reported for any turtle. The relatively narrow TRT may limit the evolutionary potential of this vulnerable turtle in the face of global warming. Future incubation experiments at a finer scale (33°C–36 °C) are warranted to refine the sex-ratio reaction norm. Field studies that monitor natural nests are imperative to evaluate conservation measures and the effect of female-biased illegal hunting and climate change. By providing data about the thermal biology of an understudied lineage of non-model species, our study helps fill gaps in our understanding of the evolution of vertebrate sex determination and its potential adaptive value.

The downside of metabolic diversity: Postingestive rearrangements by specialized insects

Deploying toxins in complex mixtures is thought to be advantageous and is observed during antagonistic interactions in nature. Toxin mixtures are widely utilized in medicine and pest control, as they are thought to slow the evolution of detoxification counterresponses in the targeted organisms. Here we show that caterpillars rearrange key constituents of two distinct plant defense pathways to postingestively disable the defensive properties of both pathways. Specifically, phenolic esters of quinic acid, chlorogenic acids (CAs), potent herbivore and ultraviolet (UV) defenses, are reesterified to decorate particular sugars of 17-hydroxygeranyllinalool diterpene glycosides (HGL-DTGs) and prevent their respective anti–herbivore defense functions. This was discovered through the employment of comparative metabolomics of the leaves of Nicotiana attenuata and the frass of this native tobacco’s specialist herbivore, Manduca sexta larvae. Feeding caterpillars on leaves of transgenic plants abrogated in each of the two pathways, separately and together, revealed that one of the fully characterized frass conjugates, caffeoylated HGL-DTG, originated from ingested CA and HGL-DTGs and that both had negative effects on the defensive function of the other compound class, as revealed by rates of larval mass gain. This negative defensive synergy was further explored in 183 N. attenuata natural accessions, which revealed a strong negative covariance between the two defense pathways. Further mapping analyses in a biparental recombinant inbred line (RIL) population imputed quantitative trait loci (QTLs) for the two pathways at distinct genomic locations. The postingestive repurposing of defense metabolism constituents reveals a downside of deploying toxins in mixtures, a downside which plants in nature have evolved to counter.

Maternal mindful eating as a target for improving metabolic outcomes in pregnant women with obesity.

Background:Maternal diet and eating behaviors have the potential to influence the metabolic milieu in pregnancies complicated by obesity, with implications for the developmental programming of offspring obesity. Emerging evidence suggests that mindfulness during eating may influence metabolic health in non-pregnant populations, but its effects in the context of pregnancy is less well understood. This study explored the individual and combined effects of mindful eating and diet quality on metabolic outcomes among pregnant women with obesity.Methods:In 46 pregnant women (body mas index >30 kg/m2) enrolled in the MomEE observational study, mindful eating (Mindful Eating Questionnaire, MEQ) and energy-adjusted dietary inflammatory index (DII, from 7 days of food photography) was assessed at two time points and the mean pregnancy values computed. Rate of gestational weight gain (GWG) and fat mass gain per week were determined from measured weight and body composition using a three-compartment method, respectively, at each assessment. Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and ghrelin concentrations were determined from fasting blood samples in late gestation (35–37 weeks). Linear regression was used to examine the association of the MEQ and its subscales (where higher values indicate more mindful eating) with metabolic outcomes, adjusting for covariates: maternal age, pregravid body mass index, race, parity, DII. The effects of the MEQ*DII interaction was also tested.Results:Total MEQ scores were not associated with rate of weight or fat mass gain, although greater distracted eating behavior was associated with greater adiposity gain (weight and fat mass). Mindful eating was inversely associated with insulin resistance, although this was attenuated to non-significance after additional adjustment for GWG. Total MEQ and the external eating subscale was significantly inversely associated with fasted ghrelin, such that less tendency to eat under the influence of external cues was associated with lower ghrelin concentrations. After false discovery rate adjustment for multiple testing, only the association of the total MEQ and external eating subscale with ghrelin levels trended towards significance. The DII was not associated with MEQ scores or outcome variables, nor did it moderate the effect of MEQ on any of the outcomes.Conclusion:This study generates early evidence to suggest that mindful eating holds potential as a tool to improve metabolic health outcomes in pregnant women with obesity, although further research is required on this topic. Prenatal lifestyle interventions should consider including mindfulness during eating to determine its efficacy for reducing adverse pregnancy and offspring health outcomes associated with maternal obesity.

How do humans impact yellow-bellied marmots? An integrative analysis

While many studies document specific human impacts on the behaviour and physiological responses of wildlife to humans, most have focused on these responses independently and over relatively short periods of time. To address this, we studied a suite of responses in yellow-bellied marmots (Marmota flaviventer) in two distinct years, 9 years apart. We first quantified the rate that vehicles, pedestrians, and bicycles passed marmot colonies, focusing on two years (2009 and 2018) to determine how, if any of these relationships changed over time. We then asked whether these disturbances were associated with marmot physiological responses including neutrophil-lymphocyte ratios (NLR), and faecal glucocorticoid metabolites levels (FGM), as well as behavioural responses including flight initiation distance (FID) and the time marmots allocated to foraging, and finally a key fitness correlate—the rate of mass gain. We found that the number of vehicles and pedestrians passing within 300 m of a marmot colony stayed relatively constant between years, while there was variation in bicycles passing by marmot colonies. Despite similar length in growing seasons, marmots at colonies that had higher disturbance gained mass more rapidly in 2018 than in 2009. By examining a suite of physiological, behavioural, and key fitness correlates, and how they changed, our findings are consistent with the hypothesis that marmots became more tolerant of human disturbances over time. This provides promise for this population in dealing with inevitable increases in eco- and nature-based tourism.

Marmot mass gain rates relate to their group’s social structure

AbstractMass gain is an important fitness correlate for survival in highly seasonal species. Although many physiological, genetic, life history, and environmental factors can influence mass gain, more recent work suggests the specific nature of an individual’s own social relationships also influences mass gain. However, less is known about consequences of social structure for individuals. We studied the association between social structure, quantified via social network analysis, and annual mass gain in yellow-bellied marmots (Marmota flaviventer). Social networks were constructed from 31 738 social interactions between 671 individuals in 125 social groups from 2002 to 2018. Using a refined dataset of 1022 observations across 587 individuals in 81 social groups, we fitted linear mixed models to analyze the relationship between attributes of social structure and individual mass gain. We found that individuals residing in more connected and unbreakable social groups tended to gain proportionally less mass. However, these results were largely age-dependent. Adults, who form the core of marmot social groups, residing in more spread apart networks had greater mass gain than those in tighter networks. Yearlings, involved in a majority of social interactions, and those who resided in socially homogeneous and stable groups had greater mass gain. These results show how the structure of the social group an individual resides in may have consequences for a key fitness correlate. But, importantly, this relationship was age-dependent.

Can diet composition estimates using stable isotope analysis of feathers predict growth and condition in nestling mountain bluebirds (Sialia currucoides)?

Insectivorous birds breeding in seasonal environments provision their dependent young during periods when prey diversity and abundance vary. Consequently, the composition and nutritional value of diets parents feed to their offspring may differ within and among broods, potentially affecting the condition of nestlings. In a population of mountain bluebirds (Sialia currucoides), we used two methods to estimate diet composition for individual nestlings: direct observation of provisioning using video recordings at 5 and 9 days post‐hatch, and stable isotopes of the δ13C and δ15N in nestling feathers and prey followed by analysis with mixing models. We determined the macronutrient content (% fat and lean mass) and estimated the metabolized energy from each type of prey. We evaluated whether different methods of estimating diet composition would produce similar results, and whether the types of prey nestlings ate at one or both ages affected their morphology, growth rates, or blood ketone concentration. We found that bluebirds fed their young 5 main types of prey: beetles, cicadas, grasshoppers, insect larvae, and spiders. Both observational and mixing model estimates of diet composition indicated that larvae are traded off with grasshoppers and that fewer larvae are provided to nestlings as the season progresses. In evaluating how diet influences individual growth and condition, estimates from direct observations had greater explanatory power than those from mixing models, indicating that diets rich in the most energy‐dense prey (greatest fat content; cicadas and larvae) were associated with larger size and higher body condition, and faster rate of mass gain and growth of tarsus. Lower value prey had more limited, specific effects on nestlings, but may still be important dietary components. While isotopic methods produced estimates of diet composition that were generally informative, when applied to explain the growth and condition of nestlings they proved less useful.

Chinese Torreya grandis cv. Merrillii seed oil affects obesity through accumulation of sciadonic acid and altering the composition of gut microbiota

Torreya grandis cv. Merrillii (Taxace, Torreya) is mainly distributed across the hilly areas of subtropical China and is well known for its nutritional value. In this study, the ameliorative effects of T. grandis seed oil on lipid metabolism were investigated, and the underlying mechanism was explored from the perspective of gut microbiota. Mice experiments showed that the rate of body mass gain in the group where the mice were fed a high-fat diet (HFD) and supplemented with 550mg/(kg·day) T. grandis seed oil (HFD+TO550 group) was 42.27%, while it was 62.25% in the HFD group. Compared with the HFD group, the liver and fat indices, total cholesterol, triglycerides, and low-density lipoprotein cholesterol were reduced in the oil-supplement groups. Moreover, the oil supplement significantly changed the fatty acid composition and alleviated pathological damage to the liver caused by the high-fat diet. Additionally, the distinct clustering of bacteria in the composition of gut microbiota was observed in the oil treatment group compared with that in the HFD group. T. grandis seed oil significantly increased the abundance of the beneficial bacteria and short-chain fatty acid producers, including Lactobacillus, Bifidobacterium, Faecalibaculum and Allobaculum. Our results suggest that the supplements of T. grandis seed oil could alleviate hyperlipidemia caused by HFD. These positive effects are considered to be related with sciadonic acid (SCA) and are partially mediated by alterations in gut microbiota composition and functionality.