Masters Theses
Date of Award
12-2022
Degree Type
Thesis
Degree Name
Master of Science
Major
Animal Science
Major Professor
Daniel J. Mathew
Committee Members
J. Lannett Edwards, Sarah E. Moorey
Abstract
During the preimplantation period of pregnancy in cattle, secretory factors released from the endometrium and conceptus interact reciprocally to transform the endometrium into an environment supportive of conceptus development. This process evokes a complex interplay of paracrine molecules, including endometrial histotroph and conceptus secretory factors, that are critical to gestational success. Conceptus origin [in vivo derived (IVD); or in vitro produced (IVP)] likely influences the secretome of both the conceptus itself and that of the endometrium. Despite their vitality, the exact composition of molecules comprising the local microenvironment during early pregnancy remain somewhat ambiguous. This study aimed to elucidate transcriptomic variation in synchronized Day 16 bovine endometrial explants co-cultured with Day 16 IVD or IVP conceptuses, as well as variation in protein content in media surrounding the co-cultured tissues. Nulliparous Angus-Holstein heifers underwent estrus synchronization and were either bred by artificial insemination (AI) on Day 0, received age and sire-matched IVP bovine blastocysts by embryo transfer (ET) on Day 7, or remained open or cyclic. Heifers that were inseminated were used to generate Day 16 IVD conceptuses, animals that underwent ET were used to generate Day 16 IVP conceptuses, and uteri from those that were synchronized but not bred served as a source of estrous stage-matched (Day 16) endometrial explants. On Day 16 of development/the estrous cycle, uteri were harvested, and the following treatments were developed: (1) 1 mL of treatment medium alone (Control Med; n = 7) or 1 mL of treatment medium cultured with (2) an IVD conceptus section (IVD Conceptus; 5 x 2 mm; n = 7), (3) an IVP conceptus section (IVP Conceptus; 5 x 2 mm; n = 7), (4) an endometrial explant (Endo Control; 8 mm, n = 13), (5) an endometrial explant co-cultured with an IVD conceptus section (Endo-IVD conceptus; n = 15), and (6) an endometrial explant co-cultured with an IVP conceptus section (Endo-IVP conceptus; n = 13). After a 12 h culture, endometrial mRNA was isolated and analyzed by RNA-Seq. Media surrounding the treatments was also collected and analyzed for protein content by LC-MS/MS. Results identified endometrial transcripts and secretory proteins dependent upon conceptus origin. Biological pathways associated with differentially expressed transcripts and proteins reveal alterations in endometrial tissue remodeling, cell proliferation, morphogenesis, and differentiation, as well as factors alluding to unique mechanisms for inducing maternal anergy to the conceptus. Compared to IVD conceptuses, IVP conceptuses modified expression of genes that reflected an altered endometrial immunology resembling inflammation and autoimmunity. Further, Endo-IVP Conceptus co-culture media had considerably less proteins compared to Endo-IVD Conceptus co-culture media, suggest a limited endometrial response. Taken together, compared to IVD conceptuses, the IVP conceptus protein microenvironment appears to be inferior in quality and potentially abundance. Ultimately, our findings demonstrate that conceptus origin significantly impacts the bovine preimplantation microenvironment. Understanding variation in endometrial response to conceptuses of unique origin will provide a foundation for elucidation of new techniques to improve bovine pregnancy outcome and reproductive efficiency.
Recommended Citation
Peterson, Katheryn D., "Identification of Endometrial Transcripts and Proteins Associated with the In Vivo Derived and In Vitro Produced Bovine Conceptus Microenvironment. " Master's Thesis, University of Tennessee, 2022.
https://trace.tennessee.edu/utk_gradthes/7042