Homozygous and Hemizygous Viability Variation on the X Chromosome of DROSOPHILA MELANOGASTER.
Homozygous and Hemizygous Viability Variation on the X Chromosome of DROSOPHILA MELANOGASTER.
复制标题
果蝇 X 染色体的纯合和半合活力变异。
作者：
W. Eanes;J. Hey;D. Houle
我们在这里报告了一项与黑腹果蝇X染色体有关的生存力近交衰退的研究。50条野生染色体来自Mt.西奈，纽约，和90个野生染色体从死亡谷，加州，提取使用标记的FM 6平衡染色体和生活力测量的纯合和杂合女性，和半合子男性，相对于FM 6男性作为标准基因型。两组染色体均未观察到统计学显著的女性遗传负荷，尽管95%置信限估计合并样本的总负荷<0.046。大约10%的死亡谷染色体作为纯合子表现出“超活力”。几乎没有证据表明X染色体上存在广泛的性别限制性有害负荷;证据表明，除超活力染色体外，男性和纯合子女性的活力效应几乎相同。生活力多基因的平均显性程度估计在0.23至0.36之间，这与常染色体变异一致，并意味着近加性。我们的结论是，有很少的遗传负荷与X染色体上的活力变化和染色体纯合性在早期的研究中观察到的总健身的大幅减少，可能主要是由于女性的性限生育能力。
We report here a study of viability inbreeding depression associated with the X chromosome of Drosophila melanogaster. Fifty wild chromosomes from Mt. Sinai, New York, and 90 wild chromosomes from Death Valley, California, were extracted using the marked FM6 balancer chromosome and viabilities measured for homozygous and heterozygous females, and for hemizygous males, relative to FM6 males as a standard genotype. No statistically significant female genetic load was observed for either chromosome set, although a 95% confidence limit estimated the total load <0.046 for the samples pooled. About 10% of the Death Valley chromosomes appear to be "supervital" as homozygotes. There is little evidence for a pervasive sex-limited detrimental load on the X chromosome; the evidence indicates nearly identical viability effects in males and homozygous females excluding the supervital chromosomes. The average degree of dominance for viability polygenes is estimated between 0.23 to 0.36, which is consistent with autosomal variation and implies near additivity. We conclude that there is little genetic load associated with viability variation on the X chromosome and that the substantial reduction in total fitness observed for chromosome homozygosity in an earlier study may be due largely to sex-limited fertility in females.