Research - Early Embryonic Development

An oocyte, a single cell, can ultimately yield a complex organism that contains many distinct cell types with specialized functions, be it a cow or a human. Within a relatively short time after fertilization, this single cell must divide and multiply into an embryo capable of interacting with the mother and establishing a pregnancy. Each embryonic cell must pass through critical developmental checkpoints that are involved in determining whether to become an interior cell (contributing to the formation of the fetus) or an outer cell (contributing to the placenta). These early decision points are just the first of many yet to come. Without this decision-making process, the plants and animals that surround us would not exist. We would not exist. Yet, despite the importance of these decision checkpoints, we do not fully understand the processes involved.

The Keefer lab uses cellular and molecular approaches to study the network of transcription factors that are involved in the maintenance of pluripotency and cell lineage determination in preimplantation embryos and embryonic stem cells. Our research will provide new insights into the basis of embryonic loss and provide schemes for improving reproductive efficiencies in livestock following traditional and assisted (cloning/transgenics) reproduction.

• Preimplantation development
• Pluripotency/Lineage determination
• Embryonic stem cells
• Nuclear transfer/transgenics

Teaching

• ANSC 435: Experimental Embryology
• ANSC 437: Animal Biotechnology

Awards and Honors

• President, International Embryo Transfer Society (IETS), 2003
• Vice president, International Embryo Transfer Society, 2002
• Board Of Governors, IETS, 1999 to 2006
• EPA Scientific and Technological Achievement Award, 1990
• Mellon Foundation Fellowship, The Johns Hopkins University, 1981-1982
• Phi Beta Kappa, 1974 (University of South Carolina)

Other Accomplishments

• Scientific Program for the 2007 Annual Conference of the International Embryo Transfer Society: Special Issue Editor - Reproduction, Fertility & Development, vol 19(1) 2007.
• Editorial board, Cloning & Stem Cells.
• Two U.S. patents (No. 5,096,822 and 5,907,080).
• Pioneering work in the development of in vitro production techniques in cattle (in vitro fertilization, intracytoplasmic sperm injection, nuclear transfer (cloning)).
• Production of first cloned goats using in vitro transfected donor cells.
• Production of cloned goats transgenic for the spider silk protein (BioSteel) and butyrylcholinesterase (Protexia).

Publications

Representative Publications

• Pant, D., Keefer, C.L. (2009). Expression of pluripotency-related genes during bovine inner cell mass explant culture. Cloning & Stem Cells 11:355-65.
• Keefer, C.L. (2008) Lessons learned from nuclear transfer (cloning). Theriogenology 69:48-54.
• He, S., Pant, D., Schiffmacher, A., Meece, A., Keefer, C.L. (2008). Lef1 mediated Wnt signaling promotes the initiation of trophoblast lineage differentiation in mouse embryonic stem cells. Stem Cells 26:842-849.
• Keefer, C.L., Pommer, J, and Robl, JM. (2007). The Role of Transgenic Livestock in the Treatment of Human Disease: Animal Agriculture’s Future through Biotechnology, Part 6. Council for Agricultural Science and Technology(CAST) Issue Paper 35.
• Keefer, C.L., Pant. D., Blomberg, L., Talbot, N.C. (2007). Challenges and prospects for the establishment of embryonic stem cell lines of domesticated ungulates. Animal Reproduction Sciences 98(1-2):147-68.
• He, S., Pant, D., Schiffmacher, A., Bischoff, S., Melican, D., Gavin, W., Keefer, C.L. (2006). Developmental expression of pluripotency determining factors in caprine embryos: Novel pattern of NANOG protein localization in the nucleolus. Molecular Reproduction and Development. 73(12):1512-22
• Keefer, C.L. 2004. Production of bioproducts through the use of transgenic animal models. Animal Reproduction Science 82-82:5-12.
• Keefer, C.L., Keyston, A., Lazaris, A., Bhatia, B., Begin, I., Bilodeau, A.S., Zhou, F.J., Kafidi,N., Wang, B., Baldassarre, H., Karatzas, C.N. (2002). Production of cloned goats following nuclear transfer using adult somatic cells. Biol. Reprod. 66: 199-203.
• Keefer, C.L., Baldassarre, H., Keyston, R., Wang, B., Bhatia, B., Bilodeau, A.S., Zhou, J.F., Leduc, M., Downey, B.R., Lazaris, A., and Karatzas, C.N. (2001). Generation of dwarf goat (capra hircus) clones following nuclear transfer with transfected and non-transfected fetal fibroblasts and in vitro matured oocytes. Biol. Reprod. 64(3):849-856.
• Keefer, C.L., Stice, S.L. and Matthews, L. (1994). Bovine inner cell mass (ICM) cells as donor nuclei in the production of nuclear transfer embryos. Biol. Reprod. 50:935-939.
• Keefer, C.L. (1989). Fertilization by sperm injection in the rabbit. Gamete Res. 22:59-69.