Research: Reproduction
Research in reproductive biology is a means for scientists to contribute to the well-being of society by increasing the supply of food animals through increased reproductive efficiency of livestock. Animal research has led to the development of assisted reproductive technologies, such as, estrous synchronization, artificial insemination, embryo transfer, in vitro fertilization, embryo culture, oocyte, embryo and sperm cryopreservation, which have been used successfully to make genetic improvement of livestock resulting in increased milk, meat and fiber production. In addition, these procedures provide means for rescuing endangered species from extinction and improving human fertility and fecundity. Moreover, these technologies are fundamental to biological research areas, such as, transgenic animal production, animal cloning, embryonic stem cells and the production of recombinant biomedical and pharmaceutical products. The Reproductive Research Program in the Department of Animal Science at The University of Tennessee is dedicated to training the next generation of young scientists, preparing them for an exciting career in reproductive research and technology.
Research interests of the faculty in the Department of Animal Science are broad and deep and range from applied studies for improving estrous synchronization and timed insemination, to unraveling the mystery of fetal-maternal chemical communication, to identifying the mechanisms of and alleviating environmental and endogenous stressors that negatively impact embryonic survival, to improved methods for in vitro embryo production and animal cloning. Perhaps one of the more unique features of the program is that the faculty, staff and graduate students work together to provide a multifaceted approach to research reproductive problems at the whole animal, cellular and molecular level.
Environmental and endogenous stressors negatively impact reproduction.
Nutritional stress may result from a diet low or deficient in essential nutrients or the ingestion of environmental toxicants, such as endophytes that infect fescue grasses or phytoestrogen. High ambient temperature can be a stress that dramatically reduces fertility. Subclinical disease, such as mastitis, is another stressor that reduces reproductive efficiency. In vitro procedures, such as in vitro embryo production, sperm, egg and embryo cryopreservation, results in the production of endogenous cellular stressors. Environmental and endogenous stressors negatively impact development of pre-fertilized eggs and embryos, the maintenance of pregnancy in females and sperm production by males. Mechanisms by which many stressors negatively impact reproduction meet at the crossroads of cellular, biochemical and molecular biology of reproductive tissues. A universal cellular response to stress is the production of stress-activated proteins and reactive oxygen species. These products may protect cells if the stressor is not too great or may send cells on the pathway of programmed cell death if over produced. Scientists in the Department of Animal Science are studying the mechanisms by which environmental and endogenous stressors negatively impact oocytes, embryos, pregnancy maintenance and testis function. The goals of this research are to develop methods for alleviating harmful stressors in whole animals and in laboratory produced embryos, cryopreserved germ cells and embryos.
Improved methods of in vitro embryos production and cloning of adult farm animals.
In vitro production of embryos is a complicated process that involves the maturation of eggs, their fertilization and culture of the resultant embryos outside the body. There is much that can be gained from these procedures, such as genetic gain for livestock, rescuing endangered species from extinction and providing infertile couples with children. Despite the progress made to date, these procedures are very inefficient. Approximately 80% of embryos produced by in vitro procedures fail to survive. Cloning of adult farm animals using somatic cell nuclear transfer is a far more complicated procedure and much more prone to failure. Despite the difficulties, it holds great promise for producing genetically superior and/or identical animals. Clonally produced animals may prove very useful for identifying genes of economic importance, such as genes that impart resistance to disease. In addition, cloning is an essential procedure for the production of transgenic animals with improved genetics traits for things such as disease resistance and increased production traits. Development of improved methods for in vitro production of embryos and large domestic animal cloning are major focus areas of research at The University of Tennessee. Visit the UT Cloning Project web site.
Fetal-maternal interactions.
Communication between the early embryo and its mother is essential for the maintenance of pregnancy. The embryo must produce chemical messages that signal its presence and the maternal uterus must respond by providing a nurturing environment. Failure of either the fetal or maternal unit to produce and respond to critical signals at the appropriate time results in pregnancy failure and fetal wastage. For example, in ruminants the conceptus produces a protein, interferon-tau, which interacts with the uterus to alter maternal endocrinology resulting in diminished uterine production of prostaglandin F2a and maintenance of luteal progesterone production. Premature or elevated production of PGF2a or insufficient/delayed production of interferon-tau may result in embryonic mortality. The proteins and prostanoids that regulate fetal-maternal interactions and embryonic growth and development are areas of research concentration in the Department of Animal Science.
