Aging effect on the phenomenon of segregation distortion in Drosophila melanogaster.
Aging effect on the phenomenon of segregation distortion in Drosophila melanogaster.
复制标题
衰老对果蝇分离扭曲现象的影响。
作者：
Y. Hiraizumi;S. Watanabe
ediscriminator （SD）是位于果蝇2号染色体着丝点区域的一个元件。当雄性在杂合条件下携带SD时，它将SD传给后代的频率大大超过理论频率的50%。SD系统由三个主要元素组成：SD轨迹本身是引起分离畸变的因素；SD的激活剂Ac(SD)，它位于SD位点的右侧，靠近SD位点，是SD发挥作用所必需的；SD的稳定器St(SD)，位于2号染色体右臂尖端，在偶联或斥力阶段具有稳定或增强SD作用的功能。关于SD的进一步信息，读者可以参考以下论文：SANDLER， HIRAIZUMI and SANDLER (1959), SANDLER and HIRAIZUMI (1960a, b), SANDLER and HIRAIZUMI (1961), PEACOCK and ERICKSON (1965), HIRAIZUMI and NAKAZIMA (1967)， HARTL, HIRAIZUMI and CROW（1967）。1961年SANDLER和HIRAIZUMI报道，SD杂合雄性在老化后，分离畸变的强度显著降低：如果k为SD后代在交配代中恢复的比例SD+/SD+ 0 × SD/SD+ 8，则k随着SD雄性变老而降低。然而，他们无法证明是SD、Ac（SD）还是St（SD）这三种元素中的哪一种导致了衰老效应，也无法证明k的下降是由于SD+数量的增加，还是由于SD后代数量的减少。本研究的目的是：(1)提供携带SD系统各种元素的雄性k值的衰老效应数据；(2)表明随着雄性年龄的增加，k值的下降实际上是由于SD+子代数量的增加，但SD子代数量与衰老效应无关。
EGREGATION Distorter (SD) is an element located in the centromeric region sof chromosome 2 of Drosophila mlanogaster. When a male carries SD in heterozygous condition, it transmits SD to its progeny in a great excess over the theoretical frequency of 50%. The SD system consists of three major elements: the SD locus itself which is the element causing segregation distortion; Activator of SD, Ac(SD), which is located to the right and close to the SD locus and is necessary, in coupling, for SD to function; and Stabilizer of SD, St(SD), which is located at the tip of the right arm of chromosome 2 and has a function, either in coupling or in repulsion phase, to stabilize, or enhance the SD action. For further information on SD, the reader may refer to the following papers: SANDLER, HIRAIZUMI and SANDLER (1959), SANDLER and HIRAIZUMI (1960a, b) , SANDLER and HIRAIZUMI (1961 ) , PEACOCK and ERICKSON (1 965), HIRAIZUMI and NAKAZIMA (1967), HARTL, HIRAIZUMI and CROW (1967). In 1961, SANDLER and HIRAIZUMI reported that when a SD heterozygous male was aged the intensity of segregation distortion was remarkably reduced: if k is the proportion of SD progeny flies recovered in the F, generation of the mating, SD+/SD+ o 0 X SD/SD+ 8 8 , k decreased when the SD males got old. However they were unable to show which of the three elements, SD, Ac(SD), or St(SD), was responsible for the aging effect nor were they able to show whether the decrease in k was due to an increase in the number of SD+, or due to a decrease in the number of SD progeny. The purpose of the present study is (1 ) to present data for the aging effect on k values of males carrying various elements of the SD system and ( 2 ) to show that the decrease in k with increasing age of the male is in fact due to an increase in the number of SD+ progeny, but that the number of SD progeny is independent of the aging effect.