Department of Genetics, University of Hawaii, Manoa, Honolulu, Hawaii 96822.
Genetics. 1984 Mar;106(3):423-34. doi: 10.1093/genetics/106.3.423.
Many translocations between the Y chromosome and a major autosome have no effect on the fertility of Drosophila melanogaster males. However, when such translocation-bearing males also carry an X chromosome deficient for a large portion of the centric heterochromatin, they are generally sterile. This has been interpreted to be the result of an interaction between the deficiency and the subterminally capped autosome. Using this observation as a starting point, we have developed a selection scheme for radiation-induced translocation resealings that depends on the prediction that fertility in the presence of such a deficient X is restored whenever the displaced autosomal tip is brought back in association with an autosomal centromere. The observation and the prediction form the basis for what is referred to as the autosomal continuity model for male fertility.-Such a mutagenesis scheme offers several advantages. (1) It is efficient, producing upward of 1% resealings in some cases. (2) It is simple; since fertility is the basis for the selective screen, many males can be tested in a single vial. (3) It can be used to simultaneously generate both duplications and deficiencies specific for chromosomal material adjacent to the original translocation breakpoints. (4) The target for mutagenesis can be mature sperm.-Analysis of the pattern of male-fertile rearrangements obtained from several translocation lines using this protocol indicates that continuity of the autosomal tips and their centromeres is neither a necessary nor sufficient condition for male fertility in the presence of a bobbed-deficient X. Thus, the simple autosomal continuity model is not adequate to explain this complicated mechanism of chromosomal control of fertility and will have to be revised accordingly. Potential future lines of inquiry toward this goal are discussed.
许多 Y 染色体与主要常染色体之间的易位对黑腹果蝇雄蝇的生育能力没有影响。然而，当这些携带易位的雄性果蝇还携带一条 X 染色体时，其大部分着丝粒异染色质缺失，它们通常是不育的。这被解释为缺失和末端带帽的常染色体之间的相互作用的结果。利用这一观察结果作为起点，我们开发了一种辐射诱导易位重连的选择方案，该方案依赖于这样的预测，即在存在这种缺失 X 的情况下，只要被置换的常染色体末端与常染色体着丝粒重新结合，生育能力就会恢复。观察结果和预测构成了所谓的雄性生育连续性模型的基础。-这种诱变方案具有几个优点。（1）它效率高，在某些情况下产生超过 1%的重连。（2）它简单；由于生育能力是选择性筛选的基础，许多雄性可以在一个小瓶中进行测试。（3）它可以用于同时产生与原始易位断点相邻的染色体物质的重复和缺失。（4）突变的目标可以是成熟的精子。-使用此方案从几个易位系中分析获得的可育重排的模式表明，在存在截短缺失 X 的情况下，常染色体末端及其着丝粒的连续性既不是雄性生育的必要条件，也不是充分条件。因此，简单的常染色体连续性模型不足以解释这种复杂的染色体对生育能力的控制机制，因此必须相应地进行修订。讨论了朝着这一目标前进的潜在未来研究方向。
