Location:2012 Annual Report
1a. Objectives (from AD-416):
Objective 1: Identify adipose tissue genes and physiological pathways underlying variation in seasonal infertility in swine. Sub-objective 1.A: Identify physiological pathways that underlie the relationship between reproductive losses due to seasonal infertility. Sub-objective 1.B: Identify changes in adipose tissue gene expression underlying variation in seasonal infertility in swine. Objective 2: Define physiological factors contributing to gastrointestinal-microbial population and immune function that are associated with seasonal infertility in sows. Sub-objective 2.A: Identify microbial popoulation changes and sensitivity to antimicrobials associated with seasonal infertility. Sub-objective 2.B: Characterize functional changes in systemic and tissue level inflammatory and immune cells that are associated with seasonal infertility in the sow. Objective 3: Determine if a relationship exists between reproductive losses due to seasonal infertility and adipocyte function, metabolism and uterine function. Sub-objective 3.A: Identify genes that are related to physiological pathways that are associated with seasonal infertility and associated adipocyte function and metabolism. Sub-objective 3.B: Identify genes that are related to physiological pathways that are associated with seasonal infertility and pregnancy failure. Objective 4: To map patterns of gene expression that underlie adipose tissue deposition and identify intervention control points to reduce fat deposition.
1b. Approach (from AD-416):
Seasonal infertility is proposed to be due to many stressors such as social environment, management, nutrition, thermal environment, and photoperiod. These factors affect neuroendocrine function of the sow, resulting in reduced fertility. It is well established that level of nutrition during lactation affects body condition and weaning-to-estrus interval. A manifestation of these stressors is an alteration in metabolic mass, a reduction in food intake and its correlated metabolic rate, which may be the triggering mechanism. Thus, seasonal infertility may also in part be due to reduced body fat and altered adipocyte function and secretion of regulatory proteins. An integrated and multidisciplinary approach, combining microarray technology with the study of endocrinology, adipocyte function, immune function and gastrointestinal microbial ecology in order to elucidate the mechanisms that contribute to seasonal infertility in the sow. This systems approach will provide an unprecedented opportunity to identify important genes and gene interactions and physiological pathways contributing to variation in seasonal fertility.
3. Progress Report:
Blood samples from gilts in an ontogeny study were analyzed for estradiol concentration. Based on the results, it was decided that all data would be reanalyzed based on puberty, either prepubescent or postpubescent. Subsequently, chicken studies were initiated because of limited resources. The influence of moulting on adipose tissue gene expression in layer chickens was examined. Adipose tissue, muscle tissue, blood samples were obtained from a moulted and a normal group of laying hens at various times during the molt. Using microarrays and quantitative real-time polymerase chain reaction (qPCR) adipose tissue gene expression was analyzed in adipose tissue. The objective of this study was to determine the effects of diets high in unsaturated fat on gene expression in broiler adipose, liver and muscle that occur over time. Day old Cobb 500 broiler chicks were randomly assigned to one of two dietary treatment groups. Test diets were prepared by adding either 5% tallow (Saturated fat) or soy oil (Unsaturated fat) to the basal diets. The starter diet was fed through day 21, at which time the birds were switched to the grower diet. Birds were sampled on days 21, 28, 35 and 42. Abdominal fat, muscle and liver samples were collected. Total fat content of the diets was similar. Gene expression has been determined in adipose tissue and will be determined in liver. This project has now been bridged to a new Project No. 6612-31000-015-00D, awaiting completion of scientific review.
1. Adipose tissue derived cytokines expressed during molting. Induced molting is an important management tool for the layer producers to maximize the laying life of a flock. Cytokines have been implicated in tissue remodeling during molting but the source of the cytokines is not known. Agricultural Research Service (ARS) researchers in Athens, Georgia, suggest that adipose tissue cytokines play a major role in regression of the ovary and oviduct during freed restricted induced molt. Microarray analysis and quantitative real-time polymerase chain reaction (qPCR) indicated little change in adipose tissue gene expression throughout the molt indicating that adipose tissue gene expression per se was not involved in the molting process. This research indicates that research into post transcriptional changes in proteins per se may be necessary to examine the molting process.
Wei, S., Duarte, M.S., Zan, L., Du, M., Jing, Z., Guan, L.L., Chen, J., Poulos, S., Hausman, G.J., Dodson, M.V. 2012. Cellular and molecular implications of mature adipocyte dedifferentiation. Journal of Genomics. 1:5-12.