Laboratory of P.J. Hansen

    RESEARCH INTERESTS

The overall research goal is to understand determinants of pregnancy success in ruminants. One major area of research is the elucidation of the cellular and molecular processes by which cellular stress disrupts embryonic function and the intercellular defense systems that embryos use to limit these effects. Of special interest is understanding the molecular basis for the thermotolerance that embryos develop as they advance through development. Focus has been on the role of heat shock proteins, antioxidants, and apoptosis in determining resistance of embryos to elevated temperature. Additional studies are being conducted to elucidate the molecular basis for breed differences in thermal resistance (i.e., cells from Brahman more resistant to heat shock than cells from Angus and Holstein). Applied studies that center largely on embryo transfer are also ongoing to develop strategies for overcoming effects of heat stress on fertility.

A second area of research concerns the importance of immunological interactions between the conceptus and mother. Much of this work focuses on progesterone since this hormone plays an important role in suppressing uterine immune function during pregnancy. It is believed progesterone acts, at least in part, by inducing secretion of other molecules that inhibit lymphocyte proliferation. In the sheep, the model species for much of the work, this molecule has been identified as a protein called ovine uterine serpin. Research goals are to document the role of ovine uterine serpin in mediating effects of progesterone and determine the specific steps in lymphocyte activation controlled by the protein. Other research is being conducted to determine the actions of various lymphocyte populations on the function of the preimplantation embryo and placenta.