Single Gene Deletions of Orexin, Leptin, Neuropeptide Y, and Ghrelin Do Not Appreciably Alter Food Anticipatory Activity in Mice

Timing activity to match resource availability is a widely conserved ability in nature. Scheduled feeding of a limited amount of food induces increased activity prior to feeding time in animals as diverse as fish and rodents. Typically, food anticipatory activity (FAA) involves temporally restricting unlimited food access (RF) to several hours in the middle of the light cycle, which is a time of day when rodents are not normally active. We compared this model to calorie restriction (CR), giving the mice 60% of their normal daily calorie intake at the same time each day. Measurement of body temperature and home cage behaviors suggests that the RF and CR models are very similar but CR has the advantage of a clearly defined food intake and more stable mean body temperature. Using the CR model, we then attempted to verify the published result that orexin deletion diminishes food anticipatory activity (FAA) but observed little to no diminution in the response to CR and, surprisingly, that orexin KO mice are refractory to body weight loss on a CR diet. Next we tested the orexigenic neuropeptide Y (NPY) and ghrelin and the anorexigenic hormone, leptin, using mouse mutants. NPY deletion did not alter the behavior or physiological response to CR. Leptin deletion impaired FAA in terms of some activity measures, such as walking and rearing, but did not substantially diminish hanging behavior preceding feeding time, suggesting that leptin knockout mice do anticipate daily meal time but do not manifest the full spectrum of activities that typify FAA. Ghrelin knockout mice do not have impaired FAA on a CR diet. Collectively, these results suggest that the individual hormones and neuropepetides tested do not regulate FAA by acting individually but this does not rule out the possibility of their concerted action in mediating FAA

Effect of air movement on the thermal insulation of avian nests

Capsule: Air movement over a nest increases the rate of cooling within the nest cup but the walls provide good thermal insulation. Aims: This study compared nests of six bird species of the families Fringillidae and Motacillidae to investigate the insulative properties in still and moving air treatments. It was hypothesized that differences in nest size and moving air would differ between species and would have a significant effect on insulatory values of the nests. Methods: Nest dimensions were measured for a total of 35 nests from six species. Thermal properties of the nests were recorded using temperature loggers within nests placed in a wind tunnel under still and moving air conditions. Results: Insulatory values and internal nest cooling rates were significantly increased by moving air. There was no significant difference between species for the thermal properties of nests but nest mass correlated with greater insulatory values and a lower rate of cooling within the nest cup. Nest wall thickness had no significant effect on the thermal characteristics of the nests. Conclusion: The use of a constructed nest mitigated the effects of air movement but the differences between species reflected difference in nest mass rather than wall thickness

Ablations of Ghrelin and Ghrelin Receptor Exhibit Differential Metabolic Phenotypes and Thermogenic Capacity during Aging

mice are adaptive. mice.Our data therefore suggest that GHS-R ablation activates adaptive thermogenic function(s) in BAT and increases EE, thereby enabling the retention of a lean phenotype. This is the first direct evidence that the ghrelin signaling pathway regulates fat-burning BAT to affect energy balance during aging. This regulation is likely mediated through an as-yet-unidentified new ligand of GHS-R

Nest desertion is not predicted by cuckoldry in the Eurasian penduline tit

Engagement in extra-pair copulations is an example of the abundant conflicting interests between males and females over reproduction. Potential benefits for females and the risk of cuckoldry for males are expected to have important implications on the evolution of parental care. However, whether parents adjust parental care in response to parentage remains unclear. In Eurasian penduline tits Remiz pendulinus, which are small polygamous songbirds, parental care is carried out either by the male or by the female. In addition, one third of clutches is deserted by both male and female. Desertion takes place during the egg-laying phase. Using genotypes of nine microsatellite loci of 443 offspring and 211 adults, we test whether extra-pair paternity predicts parental care. We expect males to be more likely to desert cuckolded broods, whereas we expect females, if they obtain benefits from having multiple sires, to be more likely to care for broods with multiple paternity. Our results suggest that parental care is not adjusted to parentage on an ecological timescale. Furthermore, we found that male attractiveness does not predict cuckoldry, and we found no evidence for indirect benefits for females (i.e., increased growth rates or heterozygosity of extra-pair offspring). We argue that male Eurasian penduline tits may not be able to assess the risk of cuckoldry; thus, a direct association with parental care is unlikely to evolve. However, timing of desertion (i.e., when to desert during the egg-laying phase) may be influenced by the risk of cuckoldry. Future work applying extensive gene sequencing and quantitative genetics is likely to further our understanding of how selection may influence the association between parentage and parental care