Biomedical subjects

Matthew C Lucy

Publications and source records attributed to Matthew C Lucy.

4 recordsLinked to original sources

PubMed2006

Luteinization of porcine preovulatory follicles leads to systematic changes in follicular gene expression.

The LH surge initiates the luteinization of preovulatory follicles and causes hormonal and structural changes that ultimately lead to ovulation and the formation of corpora lutea. The objective of the study was to examine gene expression in ovarian follicles (n = 11) collected from pigs (Sus scrofa domestica) approaching estrus (estrogenic preovulatory follicle; n = 6 follicles from two sows) and in ovarian follicles collected from pigs on the second day of estrus (preovulatory follicles that were luteinized but had not ovulated; n = 5 follicles from two sows). The follicular status within each follicle was confirmed by follicular fluid analyses of estradiol and progesterone ratios. Microarrays were made from expressed sequence tags that were isolated from cDNA libraries of porcine ovary. Gene expression was measured by hybridization of fluorescently labeled cDNA (preovulatory estrogenic or -luteinized) to the microarray. Microarray analyses detected 107 and 43 genes whose expression was decreased or increased (respectively) during the transition from preovulatory estrogenic to -luteinized (P<0.01). Cells within preovulatory estrogenic follicles had a gene-expression profile of proliferative and metabolically active cells that were responding to oxidative stress. Cells within preovulatory luteinized follicles had a gene-expression profile of nonproliferative and migratory cells with angiogenic properties. Approximately, 40% of the discovered genes had unknown function.

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PubMed2005

Relationship between follicle size at insemination and pregnancy success.

Administration of gonadotropin-releasing hormone (GnRH) induces a surge of luteinizing hormone and ovulation in a variety of species, including human beings. Our objectives were to determine the effect of follicle size at the time of ovulation on corpus luteum function and establishment and maintenance of pregnancy in cows in which ovulation was either spontaneous or induced with GnRH. GnRH-induced ovulation of follicles < or approximately = 11 mm in diameter resulted in decreased pregnancy rates and increased late embryonic mortality. This decrease in fertility was associated with lower circulating concentrations of estradiol on the day of insemination, a decreased rate of increase in progesterone after insemination, and, ultimately, decreased circulating concentrations of progesterone. In contrast, ovulatory follicle size had no apparent effect on fertility when ovulation occurred spontaneously. Follicles undergoing spontaneous ovulation do so at a wide range of sizes when they are physiologically mature. Therefore, administration of GnRH to induce ovulation likely initiates a preovulatory gonadotropin surge before some dominant follicles attain physiological maturity. GnRH-induced ovulation of follicles that are physiologically immature has a negative impact on pregnancy rates and late embryonic/fetal survival. These observations in cattle may have implications for assisted reproductive procedures in human beings.

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PubMed2004

Large-scale generation and analysis of expressed sequence tags from porcine ovary.

One method to identify the factors that control ovarian function is to characterize the genes that are expressed in ovary. In the present study, cDNA libraries from fetal, neonatal, and prepubertal porcine ovaries, pubertal ovaries on different days of the estrous cycle (Days 0 [follicle], 5, and 12 [follicle and corpus luteum]), and follicles isolated from weaned sows (diameter, 2, 4, 6, and 8 mm) were constructed and sequenced. A total of 22 176 cDNAs were sequenced, of which 15 613 were of sufficient quality for clustering. Clustering of cDNAs resulted in 8507 contigs, 6294 (74%) of which were comprised of a single sequence. Sixty-eight percent of the contigs had consensus sequences that were homologous to existing Tentative Consensus (TC) sequences or mature transcripts (ET) in The Institute for Genomic Research Porcine Gene Index. The consensus sequences were classified according to the Gene Ontology Index. Most cDNA-encoded proteins were components of the nucleus, ribosome, or mitochondrion. The proteins primarily functioned in binding, catalysis, and transport. Nearly 75% of the proteins were involved in metabolism and cell growth and/or maintenance. Analysis of the cDNA frequency across different libraries demonstrated differential gene expression within different-size follicles, between follicles and corpora lutea, and across developmental time-points. The expression of selected genes (analyzed by ribonuclease protection assay and Northern blotting) was consistent with the frequency of their respective cDNA in the individual libraries. This porcine ovary unigene set will be useful for identifying factors and mechanisms controlling ovarian follicular development in a variety of species.

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PubMed2003

Development and testing of a high-density cDNA microarray resource for cattle.

A cDNA microarray resource has been developed with the goal of providing integrated functional genomics resources for cattle. The National Bovine Functional Genomics Consortium's (NBFGC) expressed sequence tag (EST) collection was established in 2001 to develop resources for functional genomics research. The NBFGC EST collection and microarray contains 18,263 unique transcripts, derived from many different tissue types and various physiologically important states within these tissues. The NBFGC microarray has been tested for false-positive rates using self-self hybridizations and was shown to yield robust results in test microarray experiments. A web-accessible database has been established to provide pertinent data related to NBFGC clones, including sequence data, BLAST results, and ontology information. The NBFGC microarray represents the largest cDNA microarray for a livestock species prepared to date and should prove to be a valuable tool in studying genome-wide gene expression in cattle.

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