<SESSION>RADIOLETHAL AND GENETIC VULNERABILITIES OF GERM CELLS IN THE FEMALE MAMMAL : EFFECTS OF TRITIUM AND OTHER RADIATIONS COMPARED
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概要
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Earlier work in our laboratory centered on immature oocyte killing by chronically administered ^3HOH and gamma rays in mice, and on germ-cell effects of chronic ^3HOH exposures of primates in utero. More recently, we have shifted our focus to understand further the nature of the lethality target in these very sensitive cells. In the mouse, several types of radiations have now been used, including ^3H-Tdr incorporated into oocyte DNA, gamma rays delivered at various dose rates, 250 kVp x rays, neutrons of various energies, and three kinds of accelerated heavy ions (Si^<14+>, Ar^<18+>, Fe^<26+>). We have shown that the lethality target in mouse immature oocytes is non-nuclear; it is equal in cross-sectional area to the entire oocyte and is separated from the nucleus by about 4μm. A substantial body of data now points to the plasma membrane as the lethality target in these particular cells. these new insights have led to novel experimental designs using low-energy neutrons (certain other radiations should also be usable) to identify and measure radiation-induced genetic effects in immature oocytes of the mouse. Strikingly, these important effects have escaped detection heretofore. We have quantified both chromosome aberrations and dominant lethal mutations in oocytes from females exposed 8 to 12 weeks earlier. Results from these and other studies show that : 1) for immature oocyte killing in mice, chronically administered ^3HOH is of near maximum biological effectiveness, similar to the most effective neutrons and heavy ions (likely true also for female germ-cell killing in some prenatal primates), 2) tritium incorporated into DNA as ^3H-Tdr is about 100 times less effective in mouse immature oocyte killing than is tritium administered as ^3HOH, and 3) for mutagenicity in the mouse, immature oocytes appear to have approximately the same sensitivity as mature oocytes (contrary to previous claims) and show dose and LET responses similar to those obtained from genetic studies of other cells. The possible implications of these findings for women exposed to tritium are considered.
- 核融合科学研究所の論文
著者
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Dobson R.lowry
University Of California San Francisco
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Straume Tore
Lawrence Livermore National Laboratory
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Kwan T.
Lawrence Livermore National Laboratory
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Goldstein Lawrence
University of California, San Francisco
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Goldstein Lawrence
University Of California San Francisco