Coen E S, Dover G A
Cell. 1983 Jul;33(3):849-55. doi: 10.1016/0092-8674(83)90027-2.
We have examined the molecular basis of the response of individuals of D. melanogaster to artificial selection for high and low abdominal bristles. By monitoring the fate of particular rDNA spacer length variants associated with individually isolated X and Y chromosomes, we show that flies from the low bristle number selection lines have undergone an unequal exchange between the X and Y rDNA arrays. Such exchanges result in translocations between X and Y chromosomes, visualised as X.Y compound chromosomes at mitosis. Transfer of few copies of a length variant between X and Y indicates a clustering of variants. Flies that have reverted back to wild-type seemingly have undergone a second unequal exchange, giving rise to a compound X.Y chromosome containing Y rDNA of normal amounts. Unequal exchanges between X and Y rDNA arrays could contribute to the observed coevolution of rDNA sequences on these chromosomes. The biological significance of this outcome is discussed.
我们研究了黑腹果蝇个体对高腹毛和低腹毛人工选择反应的分子基础。通过监测与单独分离的X和Y染色体相关的特定核糖体DNA间隔区长度变体的命运，我们发现来自低腹毛数量选择品系的果蝇在X和Y核糖体DNA阵列之间发生了不等交换。这种交换导致X和Y染色体之间的易位，在有丝分裂时表现为X.Y复合染色体。X和Y之间少数长度变体拷贝的转移表明变体的聚集。恢复到野生型的果蝇似乎经历了第二次不等交换，产生了一个包含正常数量Y核糖体DNA的复合X.Y染色体。X和Y核糖体DNA阵列之间的不等交换可能促成了这些染色体上核糖体DNA序列的共同进化。本文讨论了这一结果的生物学意义。
