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Peter J. Hansen, Ph.D.University of Florida Department of Animal Sciences Ph.D., University of Wisconsin Postdoctoral, University of Florida Dr. P.J. Hansens's Homepage Email: Hansen@animal.ufl.edu 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.
de Castro e
Paula, L.A., and Hansen, P.J. (2008) Ceramide inhibits development
and cytokinesis and induces apoptosis in preimplantation bovine
embryos. Mol. Reprod. Dev. 75, 1063-1070. de Castro e Paula, L.A., Andrzejewski,
J., Julian, D., Spicer, L.J., and Hansen, P.J. (2008) Oxygen and
steroid concentrations in preovulatory follicles of lactating dairy
cows exposed to acute heat stress. Theriogenology 69,
805-813.
Block, J., Wrenzycki, C., Niemann, H.,
Herrmann, D., and Hansen, P.J. (2008) Effects of insulin-like growth
factor-1 on cellular and molecular characteristics of bovine
blastocysts produced in vitro. Mol. Reprod. Dev. 75,
895-903.
Jousan, F.D., Oliveira, L.J., and Hansen, P.J. (2008) Short-term
culture of bovine preimplantation embryos with insulin-like growth
factor-I prevents heat shock-induced apoptosis through activation of
the phosphatidyl 3-kinase/Akt pathway. Mol. Reprod. Dev.
75, 681-688. Brad, A.M., and Hansen, P.J.
(2007) The block to apoptosis in bovine two-cell embryos involves
inhibition of caspase-9 activation and caspase-mediated DNA damage.
Reproduction 134, 789-797. Loureiro,
B., Brad, A.M., and Hansen, P.J. (2007) Heat shock and tumor
necrosis factor-α induce apoptosis in bovine preimplantation embryos
through a caspase-9 dependent mechanism Reproduction 133,
1129-1137. Tekin,
S., Padua, M.B., Brad, A.M., Rhodes, M.L., and Hansen, P.J. (2006) Expression
and properties of recombinant ovine uterine serpin, Exp. Biol. Med.
231, 1313-1323.
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Director:
Peter J. Hansen
Co-Director:
Lokenga Badinga Webmaster: Peter J. Hansen Last updated: Monday August 25 2008 |
University of Florida Department of Animal Sciences PO Box 110910 Gainesville, Florida 32611-0910 Phone:(352) 392-5590 Fax:(352) 392-5595 |
