The effects of changes in day length on metabolism and mitochondrial enzyme activity of Catbirds (Dumetella carolinensis)

• Grant number: 14/08919-6
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: August 05, 2014
• End date: November 04, 2014
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Denis Otavio Vieira de Andrade
• Grantee: Jussara Nascimento Chaves
• Supervisor: Paul J. Schaeffer
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Institution abroad: Miami University, United States
• Associated to the scholarship: 13/12296-1 - Energy metabolism and thermal physiology of toucan-toco(Ramphastos toco), BP.MS

Abstract

Migration is a regular seasonal movement that permits birds to escape from extreme cold and to explore different sources of food. Long-distance flight is energetically demanding, so the birds must prepare for it by storing large amounts of energy. Timing of migration is controlled primarily by changes in day length. Before spring and autumn, the birds increase the food intake for deposition of large fat reserves, which may account for 50 % of live body mass. Large fuel stores may require a large musculature for transport, some studies show the hypertrophy of flight muscles before migration, accompanied by modification of aerobic capacity of the tissue and an increase in the capacity for fatty acid oxidation (FAO). The high level of muscular activity also requires a high level of activity of organs such as the heart and digestive tract. These adaptations affect the basal metabolic rate, which can be up to 40% greater before the migration compared with the average level of the rest of year. Our focal specie, the grey Catbird (Dumetella carolinensis) is a passerine known for responding to migratory demands with increased fat stores and hypertrophy of flight muscles. Hence, given the phenotypic flexibility occurring in these birds, in the present study we will evaluate the effects of alterations in day length on metabolism (summit and basal), body composition and on oxidative capacity of tissues, the heart and flight muscles, of Catbirds before the autumn migration. Will be used 20 catbirds equally divided in two different room conditions: the control group under 14:10 L:D (light:dark) and the experimental group under 10:14 L:D. During five weeks we will weigh the birds, measure the body composition and both summit and basal metabolic rate weekly. At the end they will be euthanized and we will weigh the mass of the heart and the flight muscle (pectoralis) and also measure mitochondrial enzyme activity (citrate synthase and cytochrome oxidase assays) of these tissues. (AU)