About Dawit
Research in my laboratory focuses on understanding the molecular mechanisms that regulate oocyte maturation and early embryo development, with a particular emphasis on bovine models. Our research is organized around three main areas: (1) Identifying genes and regulatory molecules involved in oocyte maturation and early embryogenesis; (2) Examining the roles of extracellular vesicle (EV)–associated microRNAs and proteins in ovarian function and fertility; and (3) Using organoid technology to study bovine oviduct physiology and to generate physiologically relevant maternal factors with potential applications in assisted reproductive technologies (ART).
Over the past decade, my research has also examined how embryos respond to various culture environments (in vitro or in vivo) and environmental stressors, with a focus on transcript and epigenomic modulation. Currently, my lab is exploring the mechanisms that support embryo survival under suboptimal environmental conditions. To this end, we employ cutting-edge tools such as CRISPR-Cas9 and siRNA-mediated knockdown of the KEAP1 gene - the cytoplasmic inhibitor of NRF2 - in bovine oocytes and embryos. This approach aims to enhance NRF2 availability and promote the transcription of antioxidant enzymes critical for cellular protection.
Another active research area in the lab investigates EV-mediated molecular signaling in bovine follicular cells, oocytes, and preimplantation embryos, particularly in the context of development and stress response modulation. A major focus at the Animal Reproduction and Biotechnology Laboratory (ARBL) is the development of a 3D organoid culture system to model bovine embryo-oviduct interactions in vitro, enabling us to study the role of EVs in embryo-maternal communication.
Findings from this research are expected to contribute to the identification of molecular markers of oocyte and embryo competence, as well as strategies to enhance embryo survival in assisted reproductive technologies in cattle - with potential applications in human reproductive medicine.
Education
Ph.D., University of Bonn, Germany, 2004M.Sc, University of Bonn, Germany, 2000B.Sc., Haramaya University of Agriculture, Ethiopia, 1990
Publications
Nico G Menjivar, Ahmed Gad, Riley E Thompson, Mindy A Meyers, Soham Ghosh, Fiona K Hollinshead, Dawit Tesfaye 2025. Organoids simulating the bovine oviduct mediate the embryo-maternal interface via extracellular vesicle-transmitted signaling, Human Reproduction Open, hoaf076, https://doi.org/10.1093/hropen/hoaf076Heather M Rogers, Ahmed Gad, Gentry K Cork, Nico G Menjivar, William B Schoolcraft, Dawit Tesfaye, Ye Yuan (2025): Age-related integrative transcriptomic profiling of human granulosa cells reveals mRNA-microRNA regulatory network associated with key ovulation dynamics, Biology of Reproduction, 2025;, ioaf034, https://doi.org/10.1093/biolre/ioaf034E Held-Hoelker, J Kurzella, C Benedetti, H Habermann, F Rings, E Tholen, D Tesfaye, M Hoelker. 2025. The mitochondrial bioenergetic profile in response to L-Carnitine as a clue for vitality of in vitro produced bovine embryos cultured under serum enriched conditions. Theriogenology, Volume 251,117746, ISSN 0093-691X, https://doi.org/10.1016/j.theriogenology.2025.117746Luca Angi Souza, Nico G. Menjivar, Ahmed Gad, Paulo Henrique Groppo Rodrigues, Leticia Rabello da Silva Sousa, Paola Maria da Silva Rosa, Alessandra Bridi, Dawit Tesfaye, Juliano Coelho da Silveira 2026: Small extracellular vesicles from follicular fluid as transport carriers of LHR: possible mediators of follicle growth and dominance acquisition in bovine reproduction. Anim Reprod. 2026;23(1):e20250051 | https://doi.org/10.1590/1984-3143-AR2025-0051Dessie Salilew-Wondim, Ernst Tholen, Christine Große-Brinkhaus, Eva Held-Hoelker, Dennis Miskel, Franca Rings, Karl Schellander, Urban Besenfelder, Vitezslav Havlicek, Dawit Tesfaye & Michael Hoelker (2025): Sexually dimorphic gene expression responses of bovine embryos to the maternal microenvironment on day 13 of gestation. BMC Genomics 26, 372. https://doi.org/10.1186/s12864-025-11570-5M. Schreiber, C. Benedetti, M. Rahimi, H. Habermann, F. Rings, E. Tholen, D. Tesfaye, M. Hoelker, E. Held-Hoelker. 2025. Tauroursodeoxycholic acid (TUDCA) improves cryo-resilience and lowers energy turnover via affecting the mitochondrial bioenergetic profile in bovine embryos, Theriogenology, Volume 249, 2026, 117632, ISSN 0093-691X, https://doi.org/10.1016/j.theriogenology.2025.117632.Eva Held-Hoelker, Lientje Sophie Haake, Jessica Kurzella, Maibritt Schreiber, Christina Dauben, Dessie Salilew-Wondim, Nasser Ghanem, Franca Rings, Christine Große-Brinkhaus, Ernst Tholen, Dawit Tesfaye, Michael Hoelker (2025). Heat stress during maturation of bovine oocytes profoundly impacts the mitochondrial bioenergetic profile and causes endoplasmic reticulum stress in subsequent blastocysts, Biology of Reproduction, ioaf070, https://doi.org/10.1093/biolre/ioaf070Nico G Menjivar, Jaiden Oropallo, Samuel Gebremedhn, Luca A Souza, Ahmed Gad, Christian M Puttlitz, Dawit Tesfaye. 2024. MicroRNA Nano-Shuttles: Engineering Extracellular Vesicles as a Cutting-Edge Biotechnology Platform for Clinical Use in Therapeutics. Biol Proced Online 26, 14. Joyce K, Gad A, Menjivar NG, Gebremedhn S, Heredia D, Dubeux G, Lopez-Duarte MC, Bittar J, Gonella-Diaza A, Tesfaye D. 2024. Seasonal environmental fluctuations alter the transcriptome dynamics of oocytes and granulosa cells in beef cows. J Ovarian Res;17(1):201.Feugang JM, Gad A, Menjivar NG, Ishak GM, Gebremedhn S, Gastal MO, Dlamini NH, Prochazka R, Gastal EL, Tesfaye D. 2024. Seasonal influence on miRNA expression dynamics of extracellular vesicles in equine follicular fluid. J Anim Sci Biotechnol;15(1):137.Dessie Salilew-Wondim, Michael Hoelker, Eva Held-Hoelker, Franca Rings, Ernst Tholen, Christine Große-Brinkhaus, Karl Shellander, Carina Blaschka, Urban Besenfelder, Vita Havlicek, Dawit Tesfaye. 2024. Sexual dimorphic miRNA-mediated response of bovine elongated embryos to the maternal microenvironment. PLoS ONE 19(2).Ahmed Gad, Nico G Menjivar, Rachel Felton, Barbara Durrant, Dawit Tesfaye, Elena Ruggeri. 2024. Mapping the follicle-specific regulation of extracellular vesicle-mediated microRNA transport in the southern white rhinoceros (Ceratotherium simum simum). Biology of Reproduction. ioae081.
Research Specialty
Reproductive Biology- Molecular regulation of early embryo development