Ocalewicz K, Dobosz S, Kuzminski H
Department of Ichthyology, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland.
Cytogenet Genome Res. 2012;137(1):1-6. doi: 10.1159/000339330. Epub 2012 Jul 6.
Cytogenetic screening of the androgenetic brook trout (Salvelinus fontinalis, Mitchill 1814) offspring hatched from eggs exposed to 420 Gy of X-radiation before insemination exhibited residues of the irradiated maternal nuclear genome in the form of small chromosome fragments. Remnants of the irradiated chromosomes had different sizes, and their number varied intraindividually from 1 to 15. To efficiently pass through the series of the cell divisions, such chromosome fragments must have had functional kinetochores. Distribution patterns of the telomeric hybridization signals on the chromosome fragments enabled us to distinguish their 3 groups: (i) telomere-less ring chromosomes with fused broken chromosome arms, (ii) rings formed in the course of fusion of the radiation-broken chromosome arm with the opposite telomeric region and exhibiting interstitial telomeric signals at the fusion point, and (iii) chromosome fragments with fused unprotected sister chromatids of 1 broken arm and intact telomeres from the other arm. Disturbances during segregation of such fragments, mainly breakages during anaphase, may partially explain intraindividual variation in the number and size of the chromosome fragments observed in the androgenetic brook trout.
对受精前经420戈瑞X射线照射的鱼卵孵化出的雄核发育溪红点鲑（Salvelinus fontinalis, Mitchill 1814）后代进行细胞遗传学筛查，结果显示，受照射的母体核基因组以小染色体片段的形式残留下来。受照射染色体的残余片段大小各异，其数量在个体内从1到15不等。为了有效地通过一系列细胞分裂，此类染色体片段必定具有功能性着丝粒。染色体片段上端粒杂交信号的分布模式使我们能够区分出它们的3种类型：（i）具有融合断染色体臂的无端粒环状染色体；（ii）由辐射断裂的染色体臂与相对端粒区域融合形成、且在融合点处呈现居间端粒信号的环状染色体；（iii）具有1条断裂臂的未受保护的姐妹染色单体融合且另一条臂具有完整端粒的染色体片段。此类片段在分离过程中的紊乱情况，主要是后期的断裂，可能部分解释了在雄核发育溪红点鲑中观察到的染色体片段数量和大小的个体内差异。
