Response to Farrokhi et al.'s statistical comments on 'no seasonal variation in physical activity of Han Chinese living in Beijing'

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Lifelongα-tocopherol supplementation increases the median life span of C57BL/6 mice in the cold but has only minor effects on oxidative damage

The effects of dietary antioxidant supplementation on oxidative stress and life span are confused. We maintained C57BL/6 mice at 7 ± 2°C and supplemented their diet with α-tocopherol from 4 months of age. Supplementation significantly increased (p = 0.042) median life span by 15% (785 days, n = 44) relative to unsupplemented controls (682 days, n = 43) and also increased maximum life span (oldest 10%, p = 0.028). No sex or sex by treatment interaction effects were observed on life span, with treatment having no effect on resting or daily metabolic rate. Lymphocyte and hepatocyte oxidative DNA damage and hepatic lipid peroxidation were unaffected by supplementation, but hepatic oxidative DNA damage increased with age. Using a cDNA macroarray, genes associated with xenobiotic metabolism were significantly upregulated in the livers of female mice at 6 months of age (2 months supplementation). At 22 months of age (18 months supplementation) this response had largely abated, but various genes linked to the p21 signaling pathway were upregulated at this time. We suggest that α-tocopherol may initially be metabolized as a xenobiotic, potentially explaining why previous studies observe a life span extension generally when lifelong supplementation is initiated early in life. The absence of any significant effect on oxidative damage suggests that the life span extension observed was not mediated via any antioxidant properties of α-tocopherol. We propose that the life span extension observed following α-tocopherol supplementation may be mediated via upregulation of cytochrome p450 genes after 2 months of supplementation and/or upregulation of p21 signaling genes after 18 months of supplementation. However, these signaling pathways now require further investigation to establish their exact role in life span extension following α-tocopherol supplementation

Testing the carbohydrate insulin model in mice : Erroneous critique does not alter previous conclusion

We are grateful to Dr Kevin Hall of the NIH for comments on an earlier draft of this paper, and Dr Stephan Guyenet for his informative blog posts on the CIM. Our study of mouse diets was funded by the strategic research program of the Chinese Academy of Sciences (XDB13030100).Peer reviewedPublisher PD

Regulation of intestinal growth in response to variations in energy supply and demand

Biotechnology and Biological Sciences Research Council (BBSRC). Grant Number: BB/P009875/1 Science Foundation Ireland. Grant Number: SFI/16/BBSRC/3389Peer reviewedPublisher PD

Trapped in the darkness of the night: thermal and energetic constraints of daylight flight in bats

Bats are one of the most successful mammalian groups, even though their foraging activities are restricted to the hours of twilight and night-time. Some studies suggested that bats became nocturnal because of overheating when flying in daylight. This is because—in contrast to feathered wings of birds—dark and naked wing membranes of bats efficiently absorb short-wave solar radiation. We hypothesized that bats face elevated flight costs during daylight flights, since we expected them to alter wing-beat kinematics to reduce heat load by solar radiation. To test this assumption, we measured metabolic rate and body temperature during short flights in the tropical short-tailed fruit bat Carollia perspicillata at night and during the day. Core body temperature of flying bats differed by no more than 2°C between night and daytime flights, whereas mass-specific CO2 production rates were higher by 15 per cent during daytime. We conclude that increased flight costs only render diurnal bat flights profitable when the relative energy gain during daytime is high and risk of predation is low. Ancestral bats possibly have evolved dark-skinned wing membranes to reduce nocturnal predation, but a low degree of reflectance of wing membranes made them also prone to overheating and elevated energy costs during daylight flights. In consequence, bats may have become trapped in the darkness of the night once dark-skinned wing membranes had evolved

Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing

Acknowledgements The authors thank Gabriele Kirchhof, Silke Werner, Klaus Gerling and Karsten Knop from the Institute of Animal Welfare and Animal Husbandry of the Friedrich-Loeffler-Institut for technical help and Catherine Hambly from the Institute of Biological and Environmental Sciences of the University of Aberdeen for the isotope analysis. Financial support statement This research received no specific grant from any funding agency, commercial or not-for-profit sectionPeer reviewedPublisher PD

Validating accelerometry-derived proxies of energy expenditure using the doubly-labelled water method in the smallest penguin species

Acknowledgements We are grateful to Dr Catherine Hambly and Peter Thompson for technical assistance with the isotope analysis for the doubly labelled water measurements. We thank Parks Victoria (in particular, the rangers at Gabo Island and Port Campbell Offices) and Kevin Lotte for logistical support. Funding This project was funded by the Holsworth Wildlife Research Endowment – Equity Trustees Charitable Foundation and the Ecological Society of Australia and Deakin University internal funds.Peer reviewedPublisher PD

Temporal Variability of Tungsten and Cobalt in Fallon, Nevada

BACKGROUND: Since 1997, Fallon, Nevada, has experienced a cluster of childhood leukemia that has been declared “one of the most unique clusters of childhood cancer ever reported.” Multiple environmental studies have shown airborne tungsten and cobalt to be elevated within Fallon, but the question remains: Have these metals changed through time in correspondence with the onset of the leukemia cluster? METHODS: We used dendrochemistry, the study of element concentrations through time in tree rings, in Fallon to assess temporal variability of airborne tungsten and cobalt since the late 1980s. The techniques used in Fallon were also tested in a different town (Sweet Home, OR) that has airborne tungsten from a known source. RESULTS: The Sweet Home test case confirms the accuracy of dendrochemistry for showing temporal variability of environmental tungsten. Given that dendrochemistry works for tungsten, tree-ring chemistry shows that tungsten increased in Fallon relative to nearby comparison towns beginning by the mid-1990s, slightly before the onset of the cluster, and cobalt has been high throughout the last ~ 15 years. Other metals do not show trends through time in Fallon. DISCUSSION: Results in Fallon suggest a temporal correspondence between the onset of excessive childhood leukemia and elevated levels of tungsten and cobalt. Although environmental data alone cannot directly link childhood leukemia with exposure to metals, research by others has shown that combined exposure to tungsten and cobalt can be carcinogenic to humans. CONCLUSION: Continued biomedical research is warranted to directly test for linkage between childhood leukemia and tungsten and cobalt

The relationship between female adiposity and physical attractiveness amongst adults in rural Ranaka village, Botswana

Objective: The aim was to assess the relationship between female adiposity and physical attractiveness among men and women in Botswana. Design: A cross-sectional study was undertaken. Setting: Ranaka rural village, Botswana. Subjects: Randomly selected adults (n = 113, men = 48 and women = 65), 18–50 years old were recruited. Outcome measures: Scores to indicate the attractiveness of 21 images of female bodies that represented different percentage body fat (%BF) according to participants’ age, gender and body mass index (BMI) were recorded. Results: The perceptions of physical attractiveness of female body size were similar among men and women, regardless of significant differences between the BMI of men and women. Younger (18–30 years) and older participants (31–50 years) separately, as well as underweight/normal weight versus overweight/obese groups all gave higher attractiveness scores for images with a lower %BF. All groups gave the highest score for the same image (%BF of 19% and waist:hip ratio (WHR) of 0.72), and the lowest score for an image with %BF of 49% and WHR of 0.81. There was a significant negative correlation between attractiveness score and %BF of the images for all groups, but no significant correlation between the attractiveness scores for the images and WHR. There was a consistent outlier in the graphs between attractiveness score and %BF with a % BF of 32% and a WHR of 0.61, with a relatively high score of 7.4 out of 9 for all groups. Conclusions: Participant groups according to gender, age or BMI gave similar attractiveness scores for leaner female body images

Thyroid hormones correlate with resting metabolic rate, not daily energy expenditure, in two charadriiform seabirds

K. Woo, M. Le Vaillant, T. van Nus, and especially A. Wesphal, J. Schultner and I. Dorresteijn, assisted with field work, often under unpleasant conditions. K. Wauthier was instrumental in wrestling the gamma counter into submission. P. Redman and C. Hambly conducted the isotopic analyses. K. Scott and K. Campbell provided the FoxBox. K.H.E. benefited from a Natural Sciences and Engineering Research Council (NSERC) Vanier Scholarship, Association of Canadian Universities for Northern Studies Garfield Weston Northern Studies Award and the Arctic Institute of North America Jennifer Robinson Scholarship. Research support came from Bird Studies Canada/Society of Canadian Ornithologists James Baillie Award, Animal Behavior Society Research Grant, American Ornithologists’ Union Research Grant, Frank Chapman Research Grant, the Waterbird Society Nisbet Grant and NSERC Discovery Grants to J.F.H. and W.G.A. Any use of trade names is for descriptive purposes only and does not imply endorsement by the US Government.Peer reviewedPublisher PD