|Mccoard, Susan - FORMER ARS EMPLOYEE|
|Fahrenkrug, Scott - UNIV. MINNESOTA|
|Alexander, Leeson - UNIV. MINNESOTA|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: October 8, 2002
Publication Date: November 20, 2002
Citation: MCCOARD, S.A., WISE, T.H., FAHRENKRUG, S.C., ALEXANDER, L.J., FREKING, B.A., ROHRER, G.A., LUNSTRA, D.D., FORD, J.J. REGULATION OF TESTICULAR SIZE IN PIGS: COMPARATIVE GENOMICS APPROACH. PROCEEDINGS OF 8TH INTERNATIONAL PACIFIC RIM BIOTECHNOLOGY CONFERENCE. 2002. P. 56. AUCKLAND, NEW ZEALAND. Technical Abstract: The first objective was to develop a more extensive integrated map of porcine chromosome X (SSC-X) and to construct a high-resolution porcine-human comparative map of chromosome X, which harbours a quantitative trait locus (QTL) for testis size in pigs. Microsatellite markers, expressed sequence tags and functional/positional candidate genes were assigned to two Radiation Hybrid panels. A total of 92 known loci are present on at least one porcine chromosome X map. Location of 33 gene-based markers on the comprehensive map translates into an integrated comparative map that supports conservation of gene order between SSC-X and HSA-X. This integrated map revealed candidate genes for regulation of testicular size, and will be valuable for selection of candidate genes for other porcine QTLs that map to SSC-X. The second objective was to evaluate morphological developmental events and role of key endocrine and molecular markers, to identify a window of opportunity to modify testicular size. Blood and testis samples were collected between 60 days prepartum and 25 days postpartum from two breeds of boars differing in adult testicular size. Morphological and molecular markers indicated mature Sertoli cell number and testicular size is likely determined by differences in duration of the postnatal proliferative period, potentially regulated by Sertoli cell maturation and blood testis barrier formation. These events occur independently of FSH secretion, however, a role for thyroid hormone in the modification of Sertoli cell development, thereby influencing growth and differentiation of the testis in pigs is suggested. This study highlights the value of an integrated approach using comparative mapping and developmental biology for gene discovery.