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RESEARCH INTERESTS: Endocrinology of Pregnancy RESEARCH SUMMARY: The primary research areas relate to placental proteins and hormones produced during pregnancy. Work also involves development of methods in reproductive diagnosis, particularly pregnancy diagnosis. Specific research areas include developing a blood test for pregnancy in ruminant animals and to extend this to non-ruminant animals. Tests are based upon the presence of an aspartric acid proteinase in blood of pregnant animals. Pregancy-specific protein B is an aspartic acid proteinase which we have isolated from the placenta of cattle. The gene was cloned and will be studied in domestic animals. Wildlife species are also of interest in this regard. The physiological role of PSPB is being studied as well. Students learn useful techniques in radioimmunoassay, enzyme immunoassay, protein isolation and purification, electrophoresis, immunology, cell culture, molecular biology, and in vivo experimentation with large, domestic animals.
A histological section of the bovine placentome in which trophoblastic binucleated cells are stained for pregnancy-specific protein B. Measurement of this protein in serum of ruminant animals provides the only specific test for pregnancy.
REPRESENTATIVE PUBLICATIONS: Sasser, R.G., C.A. Ruder, K.A. Ivani, J.E. Butler, and W.C. Hamilton. 1986. Detection of pregnancy by radioimmunoassay of a novel pregnancy-specific protein in serum of cows and a profile of serum concentrations during gestation. Biol. Reprod. 35:936-942. Humblot, P., S. Camous, J. Martal, J. Charlery, N. Jeanguyot, M. Thibier, and G. Sasser. 1988. Diagnosis of pregnancy by radioimmunoassay of a pregnancy-specific protein in the plasma of dairy cows. Theriogenology 30:257-267. Humblot, P. and R.G. Sasser. 1990. Quantitation of pregnancy-specific protein B in the circulation of domestic goats during pregnancy. J. Reprod. Fertil. 89:205-212. Willard, ST., RG Sasser, JC Gillespie, JT Jaques, TH Welsh, Jr. and RD Randel. 1994. Methods for pregnancy determination and the effects of body condition on pregnancy status in Rocky Mountain elk (Cervus elephus nelsoni). Theriogenology 42:1095-1102. Willard, JM., DR White, CAR Wesson, J Stellflug and RG Sasser. 1995. Detection of fetal twins in sheep using a radioimmunoassay for pregnancy-specific protein B. J. Anim. Sci. 73:960-966. Alexander, BM, R. Guardia, MS Johnson, WL Van de Graff, PL. Senger and RG Sasser. 1995. Embryonic loss from 30 to 60 days post-breeding and effect of rectal palpation for pregnancy. Theriogenology 43:551-556. Stephenson, TR, JW Testa, GP Adams, RG Sasser, CC Schwartz and KJ Hundertmark. 1995. Diagnosis of pregnancy and twinning in moose by ultrasonography and serum assay. ALCES 31: 167-172. Willard, ST, RG Sasser, SJ Jaques, DR White, DA Neuendorff and RD Randel. 1998. Early pregnancy detection and the hormonal characterization of embryonic-fetal mortality in fallow deer (Dama dama). Theriogenology 49:861-869 Austin, KJ, CP King, JE Vierk, RG Sasser and TR Hansen.
1999. Pregnancy-specific protein B induces release of an alpha
Chemokine in the bovine endometrium. Endocrinology 140:542-545. Huang, F., DC Cockrell, TR Stephenson, JH Noyes and RG
Sasser. 1999. Isolation, purification and characterization
of pregnancy-specific protein B from elk and moose placenta.
Biol. Reprod 61:1056-1061. Huang, F, DC Cockrell, TR Stephenson, JH Noyes and RG Sasser. 1999 A specific radioimmunoassay for moose and elk pregnancy-specific protein B in serum. J. Wildlife Mgmt. (Accepted). |
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