RADIATION AND AGEING IN INSECTS

被引:18
作者
Lamb, Marion J. [1 ]
Smith, J. Maynard [2 ]
机构
[1] MRC Radiobiol Res Unit, Harwell, Berks, England
[2] Univ Coll London, Dept Zool, London WC1E 6BT, England
关键词
D O I
10.1016/0531-5565(64)90003-8
中图分类号
R592 [老年病学]; C [社会科学总论];
学科分类号
03 ; 0303 ; 100203 ;
摘要
It does not seem possible at present to decide whether radiation reduces the life span of insects primarily by causing mutations in the nuclei of somatic cells. But some tentative conclusions can be drawn: (i) The theory that life-shortening is primarily due to recessive somatic mutations can be rejected, for two reasons. First, if the theory were true, the difference in radio-sensivity between haploid and diploid male Habrobracon, and between male and female Drosophila, would be greater than it is. Second, the theory predicts that in females reduction in life span should be proportional to the square or to some higher power of the dose, whereas it is approximately proportional to the dose. (ii) The facts can be explained if it is assumed that life-shortening is due in part to dominant and in part to recessive mutations, but it does not follow that this assumption is true since the doses involved are large enough to cause cytoplasmic damage; if it is true, then only dominant mutations have a significant effect on individuals diploid at all loci. (iii) It is true either that adult cells are many times more resistant to the induction of recessive lethals than are sperm, or, as seems more likely, that only a small fraction of genes are needed in any particular adult tissue. (iv) It is likely that many gene changes have a dominant lethal effect in a zygote but not in an adult cell. If dominant mutations are important in radiation-induced life-shortening, they are likely to be mutations in the systems which control the activities of genes.
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页码:11 / 20
页数:10
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