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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #153333
Title: MICROARRAY PROFILING FOR DIFFERENTIAL GENE EXPRESSION IN OVARIES AND OVARIAN FOLLICLES OF PIGS SELECTED FOR INCREASED OVULATION RATE

Author
item CAETANO, ALEXANDRE - UNIV. NEBRASKA, LINCOLN
item JOHNSON, RODGER - UNIV. NEBRASKA, LINCOLN
item Ford, Johny
item POMP, DANIEL - UNIV. NEBRASKA, LINCOLN

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2004
Publication Date: 11/1/2004
Citation: Caetano, A.R., Johnson, R.K., Ford, J.J., Pomp, D. 2004. Microarray profiling for differential gene expression in ovaries and ovarian follicles of pigs selected for increased ovulation rate. Genetics. 168(3):1529-1537.

Interpretive Summary: In a long-term experiment that produced an increase in ovulation rate and litter size by direct selection for number of corpora lutea and for number of fetuses at 60 days of gestation little is known about which alleles of which genes have increased in their frequency in the selected line relative to the control line. The current study examined expression of genes related to ovarian follicular development during the final phase of follicular growth. Ovaries were collected from gilts on each of the five days preceding ovulation, and gene expression in Control line gilts was compared by microarray analysis to gene expression in Select line gilts. Genes related to ovarian steroidogenesis were expressed at a greater magnitude sooner in Control than in Select gilts. Additionally, a large number of genes related to tissue remodeling were differentially expressed in these two lines of gilts. These findings will guide subsequent research into physiological changes and allelic changes associated with increased ovulation rate in female swine.

Technical Abstract: A unique line of pigs with superior reproductive qualities was created by long-term selection based on an index of high ovulation rate and embryonic survival. The Index line ovulates on average 6.7 more ova than the randomly selected Control line. Expression profiling experiments were conducted to identify differentially expressed genes in ovarian tissues of the Index and Control lines during days 2-6 of the follicular phase of the estrous cycle. Fluorescently labeled cDNAs derived from ovary and follicle RNA pooled from animals within line, treatment day and follicle size were co-hybridized with reciprocal labeling on microarray slides (n=90) containing 4,608 follicle-derived probes printed in duplicate. Statistical analysis of the resulting ~1.6 million data points with a mixed-model approach and Bonferonni correction identified several probes with significant RNA expression differences between lines. A total of 88 and 76 unique probes, representing a set of 71 and 56 unique genes, were found to be differentially expressed in the ovary and follicle pools, respectively, of the Index and Control lines. These findings indicate that long-term selection for components of litter size has acted in part by causing significant changes in physiological control of the dynamics of follicular maturation. Genes involved with steroid synthesis, tissue remodeling and apoptosis were found to be differentially expressed between lines. In addition, expression of several genes not previously associated with ovarian physiology, or with unknown function, was different in the two selection lines, revealing potential avenues of investigation that may uncover new insight into ovarian physiology and the genetic control of reproduction.