求人情報：ポスドク Univ. of Veterinary Medicine, Vienna
日本比較内分泌学会 会員のみなさま
国立循環器病研究センターの海谷会員より、海外でのポスドク募集に関する情報をいただきました。お知らせいたします。
詳細は添付のPDFファイルをご覧下さい。
http://www.vetmeduni.ac.at/en/research/young-scientists/postdoc-programme/
======================================================================
Dear Colleagues,
the University of Veterinary Medicine, Vienna, will open next week a call for 6 PostDoctoral positions (4 years). The successful candidates will be able to choose among 21 Projects. One of my research projects was included in the selection, therefore I would be grateful if you would forward this information to potential excellent candidates.
Best wishes
Leonida
HORMONAL CONTROL OF RAPID BODY MASS CHANGES IN BIRDS
A remarkable property of migratory birds is the rapid regulation of body mass. Migratory birds can double their body mass before migration and return to their lean mass after it. Migration is often accompanied by changes in the life pattern: most passerines are diurnal but migrate at night, and in captivity, the migratory status is therefore indicated by nocturnal restlessness. The extent of subcutaneous fat is an excellent predictor of migratory disposition, suggesting that signals originating from either the adipose tissue or the gastrointestinal tract are influencing directly migratory behaviour [1, 2]. Thus, we hypothesize that hormones that indicate satiety and/or food intake can trigger the activation/deactivation of migratory restlessness in captive birds and in the decision of staying at a stopover site or resume migration in free-living birds. An excellent candidate hormone is ghrelin, a recently discovered hormone secreted by the gastrointestinal tract. In domestic galliforms ghrelin reflects the nutritional state (fasted or fed) and food availability (lipid sensor function) [3], and acts as an anorexic hormone in regulating glucose metabolism [4]. In a preliminary study in garden warblers (Passeriformes: Sylvia borin) we found that ghrelin induces an increase in migratory restlessness. Since substantial inter-individual variation for genes of the ghrelin regulatory cascade has been described in domestic birds [3], we hypothesize also that genetic variation in ghrelin metabolic pathways plays a role in individual differences in the response to the environment.
Specific Aims
We aim to understand: 1) how food intake and the nutritional state affect migratory behaviour; 2) if behavioural patterns related to migration such as pre-migratory hyperfagia are mediated by the hormone ghrelin; 3) if and how genes involved in the ghrelin pathways influence food-dependent and condition-dependent behavioural and physiological switches.
Advance in Knowledge
The results of our project will contribute to our understanding of food intake regulation and energy storage in birds. Previous studies have focused almost exclusively on domestic birds because of their commercial importance. Because Passeriformes account to about a third of all living bird species, our project will fill a substantial gap in basic knowledge regarding this taxon.
Potential applications and/or scientific impact of the project
The ghrelin system with its main components, the hormones ghrelin and obestatin and the growth hormone secretagogue receptor family, is still scarcely known but it is likely to gain more and more attention in poultry science [3]. In addition, ghrelin is directly involved in growth because of its capacity of stimulating the release of the growth hormone [3]. Thus, a better understanding of the avian ghrelin system gained through the study of our model will provide direct benefits to poultry industry. Moreover, the capacity of birds to rapidly double and the half their body mass provides an exceptional model to study metabolic syndromes. Many hormones involved in fat metabolism and food intake are shared between migratory birds and humans [3, 4], thus our model of plastic body mass regulation could help to identify genetic and physiological correlates of obesity.
1. Fusani, L., et al., Stopover decision during migration: physiological conditions predict nocturnal restlessness in wild passerines. Biology Letters, 2009. 5(3): p. 302.
2. Goymann, W., et al., Body fat influences departure from stopover sites in migratory birds: evidence from whole island telemetry. Biology Letters, 2010. 6: p. 478-481.
3. Richards, M.P. and J.P. McMurtry, The avian proghrelin system. International Journal of Peptides, 2010. 2010: p. 749401.
4. Kaiya, H., et al., Current knowledge of the roles of ghrelin in regulating food intake and energy balance in birds. General And Comparative Endocrinology, 2009. 163(1-2): p. 33-38.
--
Leonida Fusani, PhD
Professor of Physiology & Ornithology
Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna
& Department of Cognitive Biology, University of Vienna
leonida.fusani@vetmeduni.ac.at
======================================================================