There is a growing concern over the ability to detect early cellular changes that may be indicative of damage within embryos and gametes incurred from very low levels of environmental reproductive hazards such as low-level ionizing radiation. This proposal uses a novel, very sensitive assay in which effects of radiation are revealed as a decrease in cellular proliferation in preimplantation embryos. The assay utilizes mouse embryo aggregation chimeras and has the proven ability to detect .01-.05 Gy (1 to 5 rad) given to embryos in vitro or with embryos produced from sperm irradiated in vivo. Our primary objective is to determine whether the assay is reflecting a nuclear or extra nuclear radiosensitive target in gametes and preimplantation embryos. The radiation source will be tritium, attached to a carrier (thymidine) that will concentrate irradiation to the nucleus, or, (water) that will deliver a uniform irradiation. A third carrier (polyethylene glycol, which does not enter cells) will be used in the in vitro studies to limit irradiation to the plasma membrane/cytocortex to examine the hypothesis that this might be the radiosensitive target responsible for the decrease in cellular proliferation in the chimera assay. Three different studies will be undertaken to attain our primary objective. The first one is an in vitro study that asks whether the target is nuclear or extra-nuclear (the plasma membrane/cytocortex?) for the cell proliferation decrease exhibited by cleaving embryos in the chimera assay. The second one is an in vivo study that asks 3 questions of the oocyte: 1) will a radiation exposure to the oocyte result in a proliferative disadvantage of the embryo in the chimera assay?; 2) if so, is the radiosensitive target nuclear?; 3) will the sensitivity of the oocyte--and the nature of the radiosensitive target-differ during different periods of oocyte development? The last study is also in vivo and asks whether the radiosensitive target observed with X-irradiation in spermatogenesis is nuclear. The results of these studies are crucial for determining whether this radiation-associated decrease in cellular proliferation is indicative of heritable genetic change.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES005409-02
Application #
3253688
Study Section
Radiation Study Section (RAD)
Project Start
1991-03-01
Project End
1994-02-28
Budget Start
1992-03-01
Budget End
1993-02-28
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Schools of Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
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Straume, T; Raabe, O G; Walsh, K J et al. (1997) Transmitted proliferation disadvantage from mouse oocytes labeled in vivo with [3H]thymidine: radiosensitive target considerations. Mutat Res 374:11-9
Straume, T; Raabe, O G; Walsh, K J et al. (1996) Mouse immature oocytes irradiated in vivo at 14-days of age and evaluated for transmitted effects using the aggregation embryo chimera assay. Mutat Res 356:269-73
Wiley, L M; Van Beek, M E; Raabe, O G (1994) Embryonic effects transmitted by male mice irradiated with 512 MeV/u 56Fe nuclei. Radiat Res 138:373-85
Wiley, L M; Raabe, O G; Khan, R et al. (1994) Radiosensitive target in the early mouse embryo exposed to very low doses of ionizing radiation. Mutat Res 309:83-92
Brice, E C; Wu, J X; Muraro, R et al. (1993) Modulation of mouse preimplantation development by epidermal growth factor receptor antibodies, antisense RNA, and deoxyoligonucleotides. Dev Genet 14:174-84
Oudiz, D J; Walsh, K; Wiley, L M (1993) Ethylene glycol monomethyl ether (EGME) exposure of male mice produces a decrease in cell proliferation of preimplantation embryos. Reprod Toxicol 7:101-9
Straume, T; Raabe, O G; Walsh, K J et al. (1993) Inherited effects from irradiated mouse immature oocytes detected in aggregation embryo chimeras. Mutat Res 287:243-51
Blankenship, A L; Suffia, M C; Matsumura, F et al. (1993) 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) accelerates differentiation of murine preimplantation embryos in vitro. Reprod Toxicol 7:255-61
Wiley, L M; Wu, J X; Harari, I et al. (1992) Epidermal growth factor receptor mRNA and protein increase after the four-cell preimplantation stage in murine development. Dev Biol 149:247-60