During folliculogenesis, oocytes and cumulus cells undergo many morphological and physiological changes. Transcriptome data were produced from single oocytes and corresponding cumulus cells (CC) to infer the differences in the transcript abundance from fully grown versus growing phase oocytes and surrounding CC. Using cow ovaries from an abattoir, COC were collected from follicles ranging from 3 to 8 mm in diameter. Cumulus-oocyte complexes were incubated in the supravital stain brilliant cresyl blue (BCB) as a means of separating oocytes based on the growth phase. Fully developed oocytes remained stained and were categorized as BCB+, whereas oocytes in the growing phase were colorless and were categorized as BCB-. Following the classification, COC were used for in vitro embryo production. Blastocyst yield from COC classified as BCB+, BCB- and unstained controls were 20%, 14% and 16.5%, respectively (P=0.18). Transcriptome data were also produced from oocytes and cumulus cells from BCB+ and BCB- COC. Transcripts from one long non-coding gene were differentially abundant in fully grown oocytes compared to oocytes in the growing phase. Eleven protein-coding genes were differentially expressed in cumulus cells collected from COC containing growing and fully grown oocytes. The results indicate no significant variation of transcript abundance of protein-coding genes in oocytes and limited regulation of transcript abundance in cumulus cells relative to the oocyte's growth phase in mid to large antral follicles. / Master of Science / The implementation of assisted techniques for achieving pregnancy is becoming increasingly adopted in the production of agriculturally important animals. However, most artificial reproductive methods have limited success, including in vitro embryo production. While many factors can contribute to reduced pregnancy rates relative to natural breeding, the developmental competence of the female egg is one of the many limiting factors. During its residence within the ovary, until it is fertilized by sperm, the egg is surrounded by layers of supporting cells. The egg and somatic cells interact by exchanging micro and macromolecules, but there is limited knowledge of the dynamics involving this interaction. It also remains unclear how these connections aid the egg in proceeding through development. Using a blue stain, the eggs were separated based on their stage of maturation. Then I investigated the interaction of the egg and the surrounding cells by measuring gene transcripts, which are a proxy of cellular function. Changes in the transcript abundance in the egg's surrounding cells were identified, which may be related to the egg's ability to be fertilized and proceed through embryonic development.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/111061 |
| Date | 05 January 2021 |
| Creators | Walker, Bailey Nicole |
| Contributors | Animal and Poultry Sciences, Biase, Fernando H., Cockrum, Rebecca, Ealy, Alan Dale |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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