Fluctuations In Body Mass Research Articles

Paleobiology and paleoecology of the woolly rhinoceros (Coelodonta antiquitatis) in Northern and Central Europe: New insights from multi-proxy data

The woolly rhinoceros, Coelodonta antiquitatis, was an emblematic component of Pleistocene faunas in Eurasia, which went extinct around ca. 12.5 ky BP. The loss of its tundra-steppe habitat due to climatic changes is considered the main cause for its extinction, whereas human impact was limited. In this study, we investigated the paleobiology and paleoecology of C. antiquitatis during the last glacial interval (Würm/Weichselian; 130 to 11.7 kya). We explored evolutionary trends for diet, physiology, and habitat via dental wear, enamel hypoplasia, body mass, age structure, mortality curves and stable isotopes (carbon and oxygen). Our results confirmed that C. antiquitatis was a large-sized species, with body mass around 2000–2500 kg, and with C3 grazing or mixed-feeding habits. Age structure and mortality curves revealed potential sampling and/or taphonomical biases at a few localities (e.g., Brixham cave, Ofnethöhle, North Sea), and indicated several vulnerability periods (birth, weaning, cow-calf separation/maturity) also retrieved by hypoplasia analyses. We observed some spatio-temporal fluctuations of body mass (1850–2955 kg), dietary preferences (strict to variable grazing) and hypoplasia prevalence (7.41–47.06 %) of C. antiquitatis depending on the locality, but correlation to specific climatic events (stadials-interstadials) is difficult without exact datation. These variations were however limited, highlighting a rather strict climatic niche and suggesting a high vulnerability to climatic and vegetation changes.

Moderate mass loss enhances flight performance via alteration of flight kinematics and postures in a passerine bird.

Many birds experience fluctuations in body mass throughout the annual life cycle. The flight efficiency hypothesis posits that adaptive mass loss can enhance avian flight ability. However, whether birds can increase additional wing loading following mass loss and how birds adjust flight kinematics and postures remain largely unexplored. We investigated physiological changes in body condition in breeding female Eurasian tree sparrows (Passer montanus) through a dietary restriction experiment and determined the changes in flight kinematics and postures. Body mass decreased significantly, but the external maximum load and mass-corrected total load increased significantly after 3days of dietary restriction. After 6days of dietary restriction (DR6), hematocrit, pectoralis and hepatic fat content, take-off speed, theoretical maximum range speed and maximum power speed declined significantly. Notably, the load capacity and power margin remained unchanged relative to the control group. The wing stroke amplitude and relative downstroke duration were not affected by the interaction between diet restriction and extra load. Wing stroke amplitude significantly increased after DR6 treatment, while the relative downstroke duration significantly decreased. The stroke plane angle significantly increased after DR6 treatment only in the load-free condition. In addition, the sparrows adjusted their body angle and stroke plane angle in response to the extra load, but stroke amplitude and wingbeat frequency remained unchanged. Therefore, birds can maintain and even enhance their flight performance by adjusting flight kinematics and postures after a short-term mass loss.

Fluid volume management in hemodialysis: never give up!

Every hemodialysis session starts with the question of how much fluid should be removed, which can currently not be answered precisely. Herein, we first revisit the "probing-dry-weight" concept, using the historical example of Tassin/France (practicing also "long, slow dialysis"): Mortality outcomes were, in the 1980s, better than registry data, but are nowadays similar to European average. In view of the negative primary end point in a recent trial on dry weight assessment, based on lung ultrasound-guided evaluation of fluid excess in the lungs, and a meta-analysis of prospective studies failing to show that bioimpedance-based interventions for correction of volume overload had a direct effect on all-cause mortality, we ask how to ever move forward. Clinical reasoning demands that as much information as possible should be gathered on the fluid status of patients undergoing dialysis. Besides body weight and blood pressure, measurements of bioimpedance and dialysate bolus-derived absolute blood volume can in principle be automatized, whereas lung ultrasound can be obtained routinely. In the era of machine learning, fluid management could consist of flexible target weight prescriptions, adjusted on a daily basis and accounting even for fluctuations in fluid-free body mass. In view of all the negative prospective results surrounding fluid management in hemodialysis, we propose this as a "never-give-up" approach.

Fluctuations in serum steroid hormone concentrations and body mass during growth and sexual maturation in captive northern fur seals (Callorhinus ursinus).

Northern fur seals (Callorhinus ursinus) have a distinct life history pattern comprising annual terrestrial breeding and oceanic migration, and the physiological changes associated with these patterns are of particular interest for understanding their environmental adaptations. However, owing to their oceanic distribution, limited information is available on the reproductive physiology of wild individuals during the immature stage and the winter migration period. This study aimed to determine the relationships among the seasonal hormone profiles, body growth, age, and pregnancy using monthly serum samples collected over 3–5 years from two male and two female captive individuals during pubescence and sexual maturation. Small increases in the serum testosterone signaled puberty in males aged 3 and 4 years. Thereafter, males showed considerable increases in testosterone during breeding seasons, indicating sexual maturity. Immature female serum progesterone was maintained at low levels, but after pubescence, females showed an increase in serum progesterone in August, the month next to the peak of delivery, followed by a decrease. In non-pregnant females, progesterone did not increase significantly until the next breeding season, but in pregnant females, they increased again from February to March and then gradually decreased. Immature males increased body mass constantly and reached puberty when their body mass exceeded 20 kg, and they showed seasonal weight fluctuations after puberty. These results provide fundamental information for determining sexual maturity and pregnancy in this species based on sex steroid hormones and body mass measurements.

Increasing Body Size after Exploitation in a Population of Timber Rattlesnakes (Crotalus horridus)

At a field site in northeastern New York during a 40-yr study, we measured the body sizes (total length, snout–vent length [SVL], mass) in three intrinsic groups of adult Crotalus horridus: nongravid (N) females, gravid (G) females, and males. We argue that a bounty system in effect for 75 yr caused a probable decline of the largest animals. After this lengthy period of exploitation, we observed that body sizes began to increase. Across 4 decades, the three intrinsic groups were significantly larger in the final decade (2009–18) than in the first decade (1979–88), stabilizing at a mean body mass of »710 g in N females, »870 g in G females, and »1,200 g in males. Mean SVLs of N females (94.1 cm) and males (111.0 cm) in the final 3 decades were significantly larger than their SVLs in the first decade. The body condition index (BCI) increased over time, and the intrinsic groups differed significantly in mean BCI: N females (-0.0764), G females (0.0146), and males (0.0899). Among recaptured snakes, wide fluctuations of body mass were not uncommon as most snakes experienced annual losses as well as gains. Geographic variation in body size of C. horridus is illustrated by comparing our New York population with a northern population (Massachusetts) and a southern population (Virginia). Across the species' range, we suggest that body size could be associated primarily with prey size. Because many populations of C. horridus are slow growing and long lived, correlated effects of exploitation on body size may negatively affect the snakes' reproductive biology and longevity.

Reproductive phenology and seasonal mass dynamics of black-tailed prairie dogs (Cynomys ludovicianus) at their northern range limit

Intraspecific variation is common and can be substantial in species occupying large geographic ranges. For example, populations at a poleward range limit can be exposed to more severe and variable weather, resulting in more punctuated growing seasons and, consequently, large fluctuations in body mass and additional constraints on reproductive phenology. We monitored variation in these traits in a hibernating population of black-tailed prairie dogs (Cynomys ludovicianus (Ord, 1815)) at their northern range limit across four growing seasons. Overall, individual body mass was highly dynamic both within and across growing seasons, and was correlated with sex, the presence of drought, and reproductive effort. This population experienced between-year variation in the timing of reproduction that was associated with weather variation. The influence of weather was particularly evident in 1 year during which a summer–autumn drought was followed by a severe and prolonged winter. This combination led to high overwinter mortality, substantially delayed emergences from hibernation, lower body masses at emergence from hibernation, and complete reproductive failure the following spring. Our results help to emphasize the influence of environmental conditions on levels of phenotypic variation at a species’ northern range limit, which may ultimately contribute to population viability and success.

Tryptanthrin exerts anti-breast cancer effects both in vitro and in vivo through modulating the inflammatory tumor microenvironment.

Tryptanthrin is an indole quinazoline alkaloid from the indigo-bearing plants, such as Isatis indigotica Fort. Typically, this natural compound shows a variety of pharmacological activities such as antitumor, antibacterial, anti-inflammatory and antioxidant effects. This study was conducted to assess the antitumor activity of tryptanthrin in breast cancer models both in vitro and in vivo, and to explore the important role of the inflammatory tumor microenvironment (TME) in the antitumor effects of tryptanthrin. Human breast adenocarcinoma MCF-7 cells were used to assess the antitumor effect of tryptanthrin in vitro. MTT assay and colony formation assay were carried out to monitor the antiproliferative effect of tryptanthrin (1.56~50.0 μmol L-1) on inhibiting the proliferation and colony formation of MCF-7 cells, respectively. The migration and invasion of MCF-7 cells were evaluated by wound healing assay and Transwell chamber assay, respectively. Moreover, the 4T1 murine breast cancer model was established to examine the pharmacological activity of tryptanthrin, and three groups with different doses of tryptanthrin (25, 50 and 100 mg kg-1) were set in study. Additionally, tumor volumes and organ coefficients were measured and calculated. After two weeks of tryptanthrin treatment, samples from serum, tumor tissue and different organs from tumor-bearing mice were collected, and the enzyme-linked immunosorbent assay (ELISA) was performed to assess the regulation of inflammatory molecules in mouse serum. Additionally, pathological examinations of tumor tissues and organs from mice were evaluated through hematoxylin and eosin (H&E) staining. The expression of inflammatory proteins in tumor tissues was measured by immunohistochemistry (IHC) and Western blotting. Tryptanthrin inhibited the proliferation, migration and invasion of MCF-7 cells, up-regulated the protein level of E-cadherin, and down-regulated those of MMP-2 and Snail, as suggested by the MCF-7 cell experiment. According to the results from in vivo experiment, tryptanthrin was effective in inhibiting tumor growth, and it showed favorable safety without inducing the fluctuations of body mass and organ coefficient (p > 0.05). In addition, tryptanthrin also suppressed the expression levels of NOS1, COX-2 and NF-κB in mouse tumor tissues, and regulated those of IL-2, IL-10 and TNF-α in the serum of tumor cells-transplanted mice. Tryptanthrin exerted its anti-breast cancer activities through modulating the inflammatory TME both in vitro and in vivo.

Telmisartan detection by UV spectrophotometry in mice drinking water.

Animal models are often used to test the safety and efficacy of drugs in cell culture and body systems. Several researchers deliver drugs to rodents in drinking water, although it has some limitations. For instance, drug stability, water consumption, and body mass fluctuation may change drug dose. Thus, we investigated telmisartan (TEL) stability in mice drinking water by UV spectrophotometry, and if water intake and body mass were fluctuated then it changes the predicted drug dose. The results showed that UV spectrophotometry could detect TEL at the wavelength of 300nm, and the concentration curve was set between 1.25 and 60µg/mL. Also, it remained stable in mice drinking water for 7 days at the predicted concentration. Mice gained weight after 8 weeks on a high-fat high-sucrose diet, and it was reduced by TEL 5mg/kg/day after 3 weeks. Although water intake remained stable, not adjusting the TEL concentration weekly by body mass would lead to higher consumption of TEL by mice. In conclusion, we demonstrated that body mass and water intake fluctuations significantly change the amount of drug that the animal receives, which would add bias to the experiment. TEL remains stable for at least 7 days in wrapped mice water bottles in the animal care facility, and UV spectrophotometry proved to be a simple and low-cost method to detect TEL in mice drinking water.

Effect of body mass fluctuation on the prognosis of atrial fibrillation

Objective To investigate the effect of body mass fluctuation on the prognosis of patients with atrial fibrillation. Methods The patients diagnosed with atrial fibrillation in the People′s Hospital of Xinjiang Uygur Autonomous Region from 2012 to 2014 were selected.Among the 540 patients, the patients were divided into normal body(BMI ≤ 25 kg/m2), overweight (25 kg/m2<BMI<30 kg/m2) and obesity (BMI ≥ 30 kg/m2) according to the baseline body mass.The median body mass fluctuation of the three groups was 2.40 kg, and according to the median body mass fluctuations, the patients were divided into two groups: the high body mass fluctuation group and the low body mass fluctuation group.Changes of body mass were observed and the incidence of cardiac death, acute coronary syndrome, chronic heart failure, cerebral embolism and peripheral vascular embolization were monitored. Results During the follow-up period, as the increased of body mass fluctuation, the incidence rate of end point events also increasing continuously.The main end point event was used as the composite end point (HR(95%CI): 1.03 (1.06~1.15); P=0.02), including the cardiogenic death (HR(95%CI): 1.04 (1.09~1.12); P=0.03), the incidence of acute coronary syndrome (HR(95%CI): 1.04 (0.96~1.08); P=0.06) and the heart failure incidence (HR(95%CI): 95%CI: 1.04 (1.01~1.09), P=0.04). The secondary endpoint as composite endpoint (HR(95%CI): 1.16 (1.15~1.31); P=0.01), including the cerebral embolism (HR(95%CI): 1.21 (1.23~1.54); P=0.01) and the peripheral vascular embolism (HR(95%CI): 1.03 (0.91~1.03); P=0.01). After adjusting for all confounding factors, the quartile group with the highest body mass fluctuations was 6.2% higher in the main endpoint event than the lowest body quartile and 14.2% higher in the secondary endpoint.The occurrence of major endpoint events and secondary endpoint events in the quadruple group with high body mass fluctuation was significantly higher than that in the quadruple group with the lowest body mass fluctuation(main endpoint: 4.4% vs 10.6%; (HR(95%CI): 1.86 ( 1.53 ~ 2.41); P<0.01; secondary endpoints: 15.6% vs 29.8%; (HR(95%CI) 2.12 (1.56 ~ 3.58); P<0.01). The main endpoint events were cardiogenic death (HR(95%CI): 1.85 (1.73~2.3); P<0.01); incidence of acute coronary syndrome (HR(95%CI): 1.02 (0.94~1.35); P=0.08); incidence of heart failure (HR(95%CI): 1.48 (1.28~1.62); P<0.01); secondary endpoint events were cerebral embolism (HR(95%CI): 2.23 (1.93~3.91). (P<0.01), peripheral vascular embolism (HR(95%CI): 1.05 (0.96~1.42); P=0.13). For patients with normal body mass, body mass fluctuations had no significant effect on prognosis (main endpoints: 6.1% vs 5.3%; (HR(95%CI): 1.04 (0.94 ~ 1.43); P=0.064; secondary endpoint : 16.7% vs 17.4%; (HR(95%CI): 1.12 (0.84~ 1.09); P=0.072), but for overweight and obese patients, the greater the fluctuation of body mass, the higher the incidence of adverse events (main endpoint: super-recombination: 5.8% vs 11.2%; (HR(95%CI): 1.532 (1.135 ~ 3.156); P<0.001; obese group: 8.3% vs 15.1%; (HR(95%CI): 1.584 (1.258~3.489); P<0.001; secondary end points: super recombination: 17.1% and 21.3%; (HR(95%CI): 341.00 ( 1.132~ 1.984); P=0.013; obese group: 19.4% and 25.2%; (HR(95%CI): 1.315 (1.128~2.123); P=0.018). Conclusion Body mass fluctuations can significantly affect the prognosis of patients with atrial fibrillation and has a greater impact on patients with overweight and obesity. Key words: Atrial Fibrillation; Body mass; Fluctuations; Prognosis

Researches of the assortment of drugs for the treatment of diabetes II type оn the pharmaceutical market of Ukraine

Type II diabetes is a global pandemic, as evidenced by data from a study by the International Diabetes Federation. The disease is a chronic, progressive process with a special metabolic condition that is characterized by hyperglycemia. Therapeutic effects should be aimed at eliminating the main causes of type II diabetes mellitus: insulin secretion dysfunction, a decrease in tissue resistance to insulin, or a combination of these. The aim of the work was to study the range of oral antidiabetic drugs on the pharmaceutical market of Ukraine for the treatment of type II diabetes. The objects of study were drugs used in the treatment of type II diabetes. Studies were conducted using content analysis of official sources of information. In the course of the work, the range of antidiabetic drugs, classification, mechanism of action, cost, main advantages and disadvantages of use were established. It is established that the most common dosage form for the treatment of diabetes are tablets, which occupy more than 90% of the total range of drugs. The lack of modern types of dosage forms in the group A10B is the basis for the creation of new drugs with improved biopharmaceutical and consumer properties.&#x0D; The data obtained indicate a strong dependence of the pharmaceutical market of antidiabetic drugs of Ukraine on imports, with the exception of insulin (А10В). The share of imports in the market in quantitative terms for the period under review amounted to more than 75.86% of the total market volume.&#x0D; It has been established that the use of drugs of the A10B A, A10B F groups with an affordable cost with active therapy contributes to a lower rate of development of diabetes mellitus type II and a high degree of regression to normal glucose, without affecting the fluctuations in body weight. Preparations of the new generation (A10B H, A10B J, A10B X) are highly effective with an insufficient safety profile. The high cost of drugs of these groups makes them inaccessible to the general population. It has been shown that only metformin and voglibosis have a positive effect on body mass fluctuation rates, which will ensure safe and effective glycemic control with minimal risk of hypoglycemia and without weight gain in the treatment of type II diabetes.

Fluid balance and hydration status in combat sport Olympic athletes: a systematic review with meta-analysis of controlled and uncontrolled studies.

Athletes in Olympic combat sports experience body water fluctuations resulting from training and intentional dehydration when making weight. Despite the popularity of urine specific gravity (USG) and urine osmolality (UOSM) measurement in characterizing fluid fluctuations, their utility remains questioned. This systematic review/meta-analysis examined the utility of urinary hydration indices in laboratory and field settings in Olympic combat sport athletes. 27 articles met the inclusion criteria for systematic review, 15 studies were included in the meta-analysis; with USG and UOSM the main outcome variables. Meta-regression analyses evaluated the interrelationship among body mass (BM), fluid intake, and urine measures. Significant USG alterations were observed following different sampling time frames: dehydration (ES 0.59; 95% CI 0.46-0.72; p = 0.001), follow-up period (ES 0.31; 95% CI 0.11-0.50; p = 0.002) and rehydration (ES - 0.34; 95% CI - 0.56 to - 0.12; p = 0.003). Direct comparison of laboratory (ES 0.20; 95% CI - 0.19 to 0.59; p = 0.324) and field (ES 0.35; 95% CI 0.14-0.56; p = 0.001) sampling showed marginally trivial and small effects. Small effects on UOSM were observed following dehydration (ES 0.31; 95% CI 0.12-0.74, p = 0.15), follow-up period (ES 0.39; 95% CI 0.08-0.70, p = 0.015) and rehydration (ES - 0.45; 95% CI - 0.60 to 0.30, p = 0.001). Meta-regression analysis suggests only fluid intake predicts USG alterations (p = 0.044) during rehydration protocols. There were likely small changes in both USG and UOSM readings across all experimental conditions, with moderate-to-large heterogeneity in all studies, except for USG readings during dehydration protocols. The meta-regression failed to provide conclusive evidence concerning the interrelationship among urine measures, BM fluctuations, and fluid intake.

Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals (Mirounga angustirostris) before and after lengthy at sea foraging trips (n = 89) or fasting periods on land (n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contrast to blood, mercury concentrations in female's muscle increased by 19% during the post-breeding foraging trip and did not change during the post-moulting foraging trip. While fasting, female muscle mercury concentrations increased 26% during breeding, but decreased 14% during moulting. Consequently, regardless of exposure, an animal's contaminant concentration can be markedly influenced by their annual life-history events.

Changes in body mass of postweaning juveniles of the edible dormouse,Glis glis (L.), in captivity

Edible dormice have to accumulate an adequate amount of body fat before hibernation. Because young dormice are born late in the season, they have a relatively short time for prehibernation fattening. The aim of our study was a) to determine what body mass juveniles reach prior to hibernation, and b) to examine patterns of mass gain in juvenile dormice with unlimited food supply. Dormice were kept in outdoor cages, fitted with wooden boxes and with the floor covered with soil suitable for hibernation. They were provided with water and fed ad libitum. They were weighed every 5-8 days. Of 34 juveniles (17 males and 17 females; 26 born in captivity and 8 caught in the wild), 22 began hibernation in underground cavities. The mean body mass of juveniles prior to hibernation was 89.7 $\pm$ 14.8 g. The mean daily mass gain was 0.82 g. The range of mass change varied from -4.00 to 5.71 g/day. Wild-caught juveniles most quickly gained mass during the first week in captivity with a mean rate of 4.54 g/day. We found that prior to hibernation body mass of juvenile dormice was lower than it was expected according to the literature. We show that fluctuations of body mass can be high, even in a short period of time.

Seasonal body mass fluctuations of captive Tawny Frogmouths (Podargus strigoides) are consistent with seasonal heterothermy

Prewinter fat accumulation along with the use of shallow torpor permits the survival of free-ranging Australian Tawny Frogmouths (Podargus strigoides) during winter, when prey availability is low and metabolic costs to maintain high body temperatures increase. Captive studies of these animals currently provide no direct support for this ability. We investigated mass fluctuations of 18 captive birds over 8 years at a North American zoo facility to determine whether or not body mass gains were correlated with seasonality, and subsequently provide indirect evidence for regular torpor use. We found that mass fluctuations were correlated with season, as predicted. The lowest body masses occurred during summer, and the greatest mass occurred during late fall and early winter, based on the seasons of the Northern Hemisphere. We conclude that body fat accumulation by captive Tawny Frogmouths occurs in preparation for winter when, under natural conditions, they regularly use torpor, and that Tawny Frogmouths are capable of altering physiological processes to match the environments in which they live, no matter their Southern Hemisphere origins.

Assessment of body composition and the anthropometric parameters of the military personnel during high physical load exercises

Military activities are characterized with high physical endurance exercises and the psychological load. The cadets of the last study year participate in the combat training course lasting for ten days. The combat training course is a challenge for military officers. It is characterized with the transition from the daily military study process routine in the National Defence Academy to military exercises in the external environment. The cadets face feeding limitation, sleeping deprivation, intensive and continuous training, strict discipline, etc. Such a situation requires the adaptation to a novel way of activity, which includes hardships and arduous training. We provided the assessment of the body mass fluctuation during the combat training course. We provided the analysis of anthropometric parameters before, during and after the combat training course, summarized the data of the health statement and health problems that are fixed in the medical cards. The proper body mass supports the good health capacity. The body composition undergoes changes during the higher physical load performance. The analysis of the average value of the body mass and the Body Mass Index have shown large individual changes inside the groups. Physical fitness and body composition have an adverse effect on military performance. The assessment of the results of physical fitness tests is provided differentially according to the individual corresponding age subgroup. The military personnel have a high risk for the health concerning the impact of external and internal factors. According to the review of the medical cards of the cadets group we indicated the main problems which are fixed after the combat training course. These are acute respiratory infections, dermatological problems, locomotor system problems, gastro-intestinal problems.

Body Mass and Pectoral Muscle Size Changes in African Waterfowl During Moult

Body mass and organ size dynamics during flight-feather moult vary among waterfowl species. To better understand adaptations of the African waterfowl, we measured how body masses of Spur-winged Goose (Plectropterus gambensis),South African Shelduck (Tadorna cana), Yellow-billed Duck (Anas undulata), Red-billed Teal (Anas erythrorhyncha) and Southern Pochard (Netta erythrophthalma) change during flight-feather moult. We further assessed how pectoral muscle size of Spur-winged Goose and South African Shelduck varied during the same period of flight-feather moult. Our results indicate that Spur-winged Goose and South African Shelduck underwent atrophy and subsequent regeneration of the pectoral muscles, while their body mass decreased at the onset of moult and later stabilized from the time when flight feathers were two-thirds grown until moult was completed. Body mass of Yellow-billed Duck and Red-billed Teal decreased from the onset of moult until the mid-point but thereafter increased rapidly, returning to pre-moult levels by the time moult was completed. Southern Pochard gradually lost mass from the start of moult almost until moult completion, at which time mass increased slightly.We conclude that African waterfowl exhibit different fluctuations in body mass and pectoral muscle size during flight-feather moult. Taken together, these findings suggest that no single hypothesis can fully explain the interspecific differences in the moult strategies of African waterfowl as reflected in changes in body and pectoral muscle conditions.

Life in the fat lane: seasonal regulation of insulin sensitivity, food intake, and adipose biology in brown bears.

Grizzly bears (Ursus arctos horribilis) have evolved remarkable metabolic adaptations including enormous fat accumulation during the active season followed by fasting during hibernation. However, these fluctuations in body mass do not cause the same harmful effects associated with obesity in humans. To better understand these seasonal transitions, we performed insulin and glucose tolerance tests in captive grizzly bears, characterized the annual profiles of circulating adipokines, and tested the anorectic effects of centrally administered leptin at different times of the year. We also used bear gluteal adipocyte cultures to test insulin and beta-adrenergic sensitivity in vitro. Bears were insulin resistant during hibernation but were sensitive during the spring and fall active periods. Hibernating bears remained euglycemic, possibly due to hyperinsulinemia and hyperglucagonemia. Adipokine concentrations were relatively low throughout the active season but peaked in mid-October prior to hibernation when fat content was greatest. Serum glycerol was highest during hibernation, indicating ongoing lipolysis. Centrally administered leptin reduced food intake in October, but not in August, revealing seasonal variation in the brain's sensitivity to its anorectic effects. This was supported by strong phosphorylated signal transducer and activator of transcription 3 labeling within the hypothalamus of hibernating bears; labeling virtually disappeared in active bears. Adipocytes collected during hibernation were insulin resistant when cultured with hibernation serum but became sensitive when cultured with active season serum. Heat treatment of active serum blocked much of this action. Clarifying the cellular mechanisms responsible for the physiology of hibernating bears may inform new treatments for metabolic disorders.

Contrasting effects of summer and winter warming on body mass explain population dynamics in a food-limited Arctic herbivore.

The cumulative effects of climate warming on herbivore vital rates and population dynamics are hard to predict, given that the expected effects differ between seasons. In the Arctic, warmer summers enhance plant growth which should lead to heavier and more fertile individuals in the autumn. Conversely, warm spells in winter with rainfall (rain-on-snow) can cause 'icing', restricting access to forage, resulting in starvation, lower survival and fecundity. As body condition is a 'barometer' of energy demands relative to energy intake, we explored the causes and consequences of variation in body mass of wild female Svalbard reindeer (Rangifer tarandus platyrhynchus) from 1994 to 2015, a period of marked climate warming. Late winter (April) body mass explained 88% of the between-year variation in population growth rate, because it strongly influenced reproductive loss, and hence subsequent fecundity (92%), as well as survival (94%) and recruitment (93%). Autumn (October) body mass affected ovulation rates but did not affect fecundity. April body mass showed no long-term trend (coefficient of variation, CV=8.8%) and was higher following warm autumn (October) weather, reflecting delays in winter onset, but most strongly, and negatively, related to 'rain-on-snow' events. October body mass (CV=2.5%) increased over the study due to higher plant productivity in the increasingly warm summers. Density-dependent mass change suggested competition for resources in both winter and summer but was less pronounced in recent years, despite an increasing population size. While continued climate warming is expected to increase the carrying capacity of the high Arctic tundra, it is also likely to cause more frequent icing events. Our analyses suggest that these contrasting effects may cause larger seasonal fluctuations in body mass and vital rates. Overall our findings provide an important 'missing' mechanistic link in the current understanding of the population biology of a keystone species in a rapidly warming Arctic.

Intra-specific variation in wing morphology and its impact on take-off performance in blue tits (Cyanistes caeruleus) during escape flights.

ABSTRACTDiurnal and seasonal increases in body mass and seasonal reductions in wing area may compromise a bird's ability to escape, as less of the power available from the flight muscles can be used to accelerate and elevate the animal's centre of mass. Here, we investigated the effects of intra-specific variation in wing morphology on escape take-off performance in blue tits (Cyanistes caeruleus). Flights were recorded using synchronised high-speed video cameras and take-off performance was quantified as the sum of the rates of change of the kinetic and potential energies of the centre of mass. Individuals with a lower wing loading, WL (WL=body weight/wing area) had higher escape take-off performance, consistent with the increase in lift production expected from relatively larger wings. Unexpectedly, it was found that the total power available from the flight muscles (estimated using an aerodynamic analysis) was inversely related to WL. This could simply be because birds with a higher WL have relatively smaller flight muscles. Alternatively or additionally, variation in the aerodynamic load on the wing resulting from differences in wing morphology will affect the mechanical performance of the flight muscles via effects on the muscle's length trajectory. Consistent with this hypothesis is the observation that wing beat frequency and relative downstroke duration increase with decreasing WL; both are factors that are expected to increase muscle power output. Understanding how wing morphology influences take-off performance gives insight into the potential risks associated with feather loss and seasonal and diurnal fluctuations in body mass.

Seasonal body mass changes and feed intake in spectacled bears (Tremarctos ornatus) at Zurich Zoological Garden

Many animals display seasonal patterns of behaviour and metabolism that can be also be observed in captivity. During an obesity-control program in Andean bears (Tremarctos ornatus) at Zoo Zurich, a seasonal fluctuation of body mass war observed once ideal body mass had been reached. The focus of this study was the question if metabolism of a male and three female animals was affected by seasonality according to their seasonal breeding behaviour, using data on pelleted food intake (from computer controlled feeders) and body mass (from regular weighing). The pelleted diet in the feeder boxes was provided additionally to a daily ration containing vegetables, fruits, pellets for environmental enrichment, and fish. This daily ration was adjusted, within prescribed limits, by the animal keepers depending on the previous day's consumption. Formulas developed for dogs were used to estimate the metabolizable energy (ME) content of the diet and maintenance requirement of the bears depending on their individual body mass. Energy requirements for minimum walked distances between the feeders was calculated as well as energy requirement for fat accretion or energy gained from body fat by body mass loss. Body mass showed a seasonal fluctuation with maxima in spring and minima in autumn, in contrast to the pattern typically observed in animals from the temperate zone; in the male, the body mass maximum occurred later than in the females. Feed intake from feeder boxes peaked in autumn, at the beginning of body mass gain in the females. These patterns cannot be explained as seasonal adaptations to climatic changes in the zoo environment, but match the natural breeding season of Andean bears in their natural habitat, suggesting genetically fixed photoperiodic clues. The data indicate that body mass fluctuation in a range considered ideal for the species was mostly based on the additional food whose amount was adjusted - within limits - by the keepers on a daily basis. Such adjustment, without incurring the risk of obesity in bears that are known as voracious eaters, is a good example of the skill required in animal husbandry.