events surrounding fertilization in mammalian species, particularly the horse
elucidate in vitro conditions to support stallion sperm capacitation
"My laboratory is doing research in the basic events surrounding fertilization in the horse. For instance, we are studying the molecular mechanism that signals the equine oocyte that it has been fertilized, also termed oocyte activation. This is achieved by transient calcium elevations within the cytoplasm of the oocyte. We hope that this will help us improve the success of assisted reproduction and cloning in the horse. We are also interested in the mechanisms that prepare stallion sperm for fertilization, or sperm capacitation. Understanding this process may allow the successfully application of in vitro fertilization in the horse.
Additionally we are researching the molecular factors that make the aged equine oocyte less apt for embryonic development. We have evidence that apoptosis occurs when aged oocytes are fertilized. We hope to eventually apply this knowledge to understand why older mares have decreased fertility."
selected publications listing
Bedford, S.J., Kurokawa, M., Hinrichs K., Fissore, R.A. Patterns of Intracellular Calcium Oscillations in Horse Oocytes Fertilized by Intracytoplasmic Sperm Injection: Possible Explanations for the Low Success of This Assisted Reproduction Technique in the Horse. Biol. Reprod. 70:936-944 (2004).
Bedford, S.J., Kurokawa, M., Hinrichs, K., Fissore, R.A. Intracellular calcium oscillations and activation in horse oocytes injected with equine sperm extracts or sperm. Reproduction 126:489-499 (2003).
Bedford, S.J., Varner, D.D., Meyers, S.A. Effects of cryopreservation on the acrosomal status of stallion spermatozoa. J. Reprod. Fert. Suppl. 56:133-140 (2000).
Bedford, S.J., McDonnell, S.M., Tulleners, E., King, D., and Habecker, P. Squamous cell carcinoma of the urethral process as a cause of hemospermia in a stallion with self-mutilation behavior. J. Am. Vet. Med. Assoc. 216(4):551-553 (2000).
Bedford, S.J., and McDonnell, S.M. Apparent experience-related aversion to handling for semen collection in a stallion. Theriogenology Case of the Month. J. Am. Vet. Med. Assoc. 216(4):491493 (2000).
Bedford, S.J. and McDonnell, S.M. Measurements of reproductive function in stallions treated with trimethoprim-sulfamethoxazol and pyrimethamine. J. Am. Vet. Med. Assoc. 215(9):1317-1319 (1999).
Bedford, S.J., Gowdy, H.L. and Hinrichs, K. Comparison of longevity of motility of stallion spermatozoa incubated at 38oC in different media and containers. Theriogenology 51(3):637-646 (1999).
Bedford, S.J., Hawes, M., Paradis, M.R., Mort, J.D. and Hinrichs, K. Peritonitis associated with abdominal retention of the placenta in a llama. J. Am. Vet. Med. Assoc., 209(11):1914-1916 (1996).
Bedford, S.J., Jasko, D.J., Graham, J.K., Amann, R.P. and Squires, E.L. Effect of seminal extenders containing egg yolk and glycerol on motion characteristics and fertility of stallion spermatozoa. Theriogenology 43:955-967 (1995).
Bedford, S.J., Graham, J.K., Amann, R.P. and Squires, E.L. Use of two freezing extenders to cool stallion spermatozoa to 5oC with and without seminal plasma. Theriogenology 42:571-578 (1994).
Bedford, S.J. and Hinrichs, K. The effect of insemination volume on pregnancy rates of pony mares. Theriogenology 42:571-78 (1994).
Jasko, D.J., Bedford, S.J., Cook, N.L., Mumford, E.L., Squires, E.L. and Pickett, B.W. The effect of antibiotics on motion characteristics of cooled stallion spermatozoa. Theriogenology 40:885-893 (1993).