Iurchenko N N, Koriakov D E, Zakharov I K
Genetika. 1995 Sep;31(9):1218-24.
Xz chromosome isolated from a natural population of Drosophila melanogaster is characterized by spontaneous mutability of the genes yellow, white, and signed and the appearance of chromosomal rearrangements. In mutant lines derived from the line carrying the Xz chromosome that had one, two, or three unstable visible mutations (markers), the rate of appearance of sex-linked lethal mutations was analyzed. This rate was shown to increase with an increase in the number of markers in a line. This phenomenon, termed "marker induction", might explain the phenotypic homogeneity of natural Drosophila populations. Spontaneous lethal mutations were mapped, and their nonrandom distribution along the Xz chromosome was shown. Along with common "hot spot" of lethal mutations, the derivatives for the Xz chromosomes had their own specific sites for lethal mutations. In some cases, the appearance of lethal mutations was accompanied by the formation of inversions in the Xz chromosome. The lethal destabilization of the Xz derivatives, caused by selection for accumulation of visible mutations, is associated with an increase in the number of hot spots for lethal mutations. Presumably, these hot spots are hot sites for the transposition of mobile genetic elements.
从黑腹果蝇自然种群中分离出的Xz染色体的特征是，黄色、白色和signed基因具有自发突变性以及出现染色体重排。在从携带Xz染色体的品系衍生而来的突变品系中，该染色体具有一个、两个或三个不稳定的可见突变（标记），分析了性连锁致死突变的出现率。结果表明，该比率随着品系中标记数量的增加而增加。这种现象被称为“标记诱导”，可能解释了果蝇自然种群的表型同质性。对自发致死突变进行了定位，并显示了它们在Xz染色体上的非随机分布。除了常见的致死突变“热点”外，Xz染色体的衍生物还有其自身特定的致死突变位点。在某些情况下，致死突变的出现伴随着Xz染色体倒位的形成。由选择积累可见突变导致的Xz衍生物的致死不稳定与致死突变热点数量的增加有关。据推测，这些热点是移动遗传元件转座的热点位点。
