James A P, Inhaber E R, Préfontaine G J
Genetics. 1974 May;77(1):1-9. doi: 10.1093/genetics/77.1.1.
Persistent lethal sectoring in a homothallic strain of yeast has been ascribed to tetrasomy for chromosome I. Such aneuploids can appear many generations after irradiation. The data thus indicate that an induced predisposition towards aneuploidy can be prolonged through successive post-irradiation cell divisions. Sporadic cell death in tetrasomics for chromosome I was found to result from a metabolic imbalance and not from a genetic instability conseqent to aneuploidy. This imbalance may be due to a dosage effect involving cistrons for ribosomal RNA since many of these are known to be located on chromosome I. Tetrasomy is not the only cause of persistent lethal sectoring; the phenomenon has been initiated through genetic recombination involving normal diploids. It has also been concluded that, in trisomics, equational division of the supernumerary chromosome sometimes occurs at the first meiotic division.
酵母同宗配合菌株中持续存在的致死扇形区已归因于第一条染色体的四体性。这种非整倍体在辐照后许多代都可能出现。因此，数据表明，诱导的非整倍体倾向可通过辐照后的连续细胞分裂而延长。发现第一条染色体四体性中的散发性细胞死亡是由代谢失衡导致的，而非非整倍体引起的遗传不稳定性所致。这种失衡可能是由于涉及核糖体RNA顺反子的剂量效应，因为已知其中许多位于第一条染色体上。四体性并非持续致死扇形区的唯一原因；该现象已通过涉及正常二倍体的基因重组引发。还得出结论，在三体中，额外染色体的均等分裂有时发生在第一次减数分裂时。
