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Selected AbstractsWinter energetics of Virginia opossums Didelphis virginiana and implications for the species' northern distributional limitECOGRAPHY, Issue 6 2005L. Leann KandaArticle first published online: 27 SEP 200 While climatic limitations are widely recognized as primary factors determining the distributions of many species, the physiological link between climate and species' persistence is poorly understood. The Virginia opossum Didelphis virginiana is a species for which winter energetics have been evaluated and a northern geographical limit has been hypothesized. Expansion of opossum populations beyond this limit, however, suggests that a previous winter energetics model requires modification. I update this energetics model by incorporating random foraging success to estimate the probability of opossum survival under varying winter temperature regimes. Estimation of opossum "success" for winters in Amherst, Massachusetts, since 1926 showed that juvenile females, the key breeding component of the population, would survive at a rate high enough to maintain a stable population in only 4 of the 77 yr. The model correctly predicted the fate of 13 of 14 opossums monitored in the Amherst area during the winters of 2000,2003. The current energetics model does not correctly predict autumn weight gain, but it does accurately estimate opossum winter survival. However, the model predicts that opossums should be winter-limited in areas such as Amherst, Massachusetts, where in fact they are well established. This discrepancy may be explained in three ways: weather station data do not adequately reflect available microclimates, opossums show high levels of flexibility in cold-weather foraging behavior, and most likely, humans provide food and shelter that mitigate the effect of winter. [source] Kinematic study of whole body center of mass position during gait in Parkinson's disease patients with and without festination,MOVEMENT DISORDERS, Issue 6 2010Marcelo Merello MD Abstract Gait festination (FE) can cause serious disability in Parkinson's disease (PD) patients. It is argued that the center of pressure position (COP) and body center of mass (COM) are possibly implicated in FE pathogenesis. The relationship between them remains unclear. The goal of this study was to determine spatiotemporal relationships between COM and COP in PD and to explore whether FE arises as a consequence of lack of physiological link between COP and COM during step stride. Twenty patients with idiopathic PD, in OFF state and 17-age-matched control subjects completed a 10-m walking protocol. PD patients were divided in two groups: those with FE and those without (NF). COM position, excursion, and its relationship with COP, as well as other kinematic parameters were analyzed. COM displacement along the horizontal and vertical plane was significantly lower in FE patients as was the maximum position on the movement direction axis compared with controls or NF patients. Significant difference in minimal COM position in FE patients was also observed. The percentage of stride time during which COM was situated ahead of COP along the movement axis in FE patients was significantly greater than for controls or NF patients. This would seem to indicate that FE patients are constantly attempting to align COP to COM, causing FE. The explanation might be that FE arises as a postural strategy to align COP within the area of COM displacement. Findings illustrate a putative role for postural strategies in the treatment of FE. © 2010 Movement Disorder Society [source] High ponderal index at birth predicts high estradiol levels in adult womenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2006Grazyna Jasienska Inter-individual variation in levels of sex hormones results from differences in genetic, developmental, and environmental factors. We tested a hypothesis that programming of the fetal neuroendocrine axis may predispose some women to produce higher levels of steroid hormones during their menstrual cycles as adults. One hundred forty-five regularly menstruating 24- to 36- year-old women collected daily saliva samples for one menstrual cycle. Data on women's birth weights and birth lengths were obtained from medical records. A positive relationship was observed between ponderal index at birth (an indicator of nutritional status, calculated as birth weight/(birth length)3) and levels of estradiol (E2) in menstrual cycles, after controlling for potential confounding factors. Mean E2 was 16.4 pmol/l in the low ponderal index tertile, 17.3 pmol/l in the moderate ponderal index tertile, and 19.6 pmol/l in the high ponderal index tertile (the high ponderal index group had significantly higher E2 than both low and moderate ponderal index groups, P = 0.0001). This study shows a positive association between ponderal index recorded for women at birth and levels of E2 measured during their menstrual cycles as adults. This suggests that conditions during fetal life influence adult production of reproductive hormones and may contribute to inter-individual variation in reproductive function. In addition, because large size at birth is one of the factors linked with an increased risk of breast cancer, our findings provide a physiological link for the observed positive relationship between indicators of energetic conditions during fetal growth and breast cancer in women. Am. J. Hum. Biol. 18:133,140, 2006. © 2005 Wiley-Liss, Inc. [source] Condition-dependent traits and the capture of genetic variance in male advertisement songJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2004L. S. E. Brandt Abstract The occurrence of additive genetic variance (VA) for male sexual traits remains a major problem in evolutionary biology. Directional selection normally imposed by female choice is expected to reduce VA greatly, yet recent surveys indicate that a substantial amount remains in many species. We addressed this problem, also known as the ,lek paradox', in Achroia grisella (Lepidoptera: Pyralidae), an acoustic moth in which males advertise to females with a pulsed ultrasonic song. Using a standard half-sib/full-sib breeding design, we generated F1 progeny from whom we determined VA and genetic covariance (COVA) among seven traits: three song characters, an overall index of song attractiveness, nightly singing period, adult lifespan, and body mass at adult eclosion. Because A. grisella neither feed nor drink as adults, the last trait, eclosion body mass, is considered a measure of ,condition'. We found significant levels of VA and narrow-sense heritabilities (h2) for all seven traits and significant genetic correlations (= COVAi,j /,(VA i·VA j)) between most pairs of traits (i, j). Male attractiveness was positively correlated with body mass (condition), adult lifespan, and nightly singing period, which we interpret as an energy constraint preventing males in poor condition from singing attractively, from singing many hours per night, and from surviving an extended lifespan. The positive genetic correlation (r = 0.79) between condition and attractiveness, combined with significant levels of VA for both traits, indicates that much of the variation in male song can be explained by VA for condition. Finally, we discuss the morphological and physiological links between condition and song attractiveness, and the ultimate factors that may maintain VA for condition. [source] Characterization of two melanin-concentrating hormone genes in zebrafish reveals evolutionary and physiological links with the mammalian MCH systemTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2009Jennifer R. Berman Abstract Melanin-concentrating hormone (MCH) regulates feeding and complex behaviors in mammals and pigmentation in fish. The relationship between fish and mammalian MCH systems is not well understood. Here, we identify and characterize two MCH genes in zebrafish, Pmch1 and Pmch2. Whereas Pmch1 and its corresponding MCH1 peptide resemble MCH found in other fish, the zebrafish Pmch2 gene and MCH2 peptide share genomic structure, synteny, and high peptide sequence homology with mammalian MCH. Zebrafish Pmch genes are expressed in closely associated but non-overlapping neurons within the hypothalamus, and MCH2 neurons send numerous projections to multiple MCH receptor-rich targets with presumed roles in sensory perception, learning and memory, arousal, and homeostatic regulation. Preliminary functional analysis showed that whereas changes in zebrafish Pmch1 expression correlate with pigmentation changes, the number of MCH2-expressing neurons increases in response to chronic food deprivation. These findings demonstrate that zebrafish MCH2 is the putative structural and functional ortholog of mammalian MCH and help elucidate the nature of MCH evolution among vertebrates. J. Comp. Neurol. 517:695,710, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||