Banaszek A, Fedyk S, Fiedorczuk U, Szałaj K A, Chetnicki W
Institute of Biology, University of Białystok, Białystok, Poland.
Cytogenet Genome Res. 2002;96(1-4):40-4. doi: 10.1159/000063025.
Thirty-three adult male common shrews (Sorex araneus L.) were collected from a hybrid zone between two chromosomal races that differed in Robertsonian metacentrics. Anaphase I nondisjunction frequencies were estimated on the basis of metaphase II counts. RIV and CV complex heterozygotes (four-element rings and five-element chains at meiosis I, respectively) had substantially higher nondisjunction rates than homozygotes and simple Robertsonian heterozygotes. However, at least in the case of RIV-forming hybrids, increased nondisjunction frequency did not result from malsegregation of the heterozygous complex. Extra elements found in hyperploid spreads were most frequently acrocentrics, that could not originate from a fully metacentric multivalent. Complex heterozygotes were also characterized by higher frequencies of univalents observed at diakinesis I. However, univalents did not originate from complex configurations, which were regularly formed with usually one chiasma per chromosome arm. Hence, we suppose that the presence of multivalents in the cell affects pairing and segregation of other elements at meiosis I.
从两个罗伯逊中着丝粒不同的染色体族的杂交区域收集了33只成年雄性普通鼩鼱（Sorex araneus L.）。根据中期II计数估计后期I不分离频率。RIV和CV复合杂合子（分别在减数分裂I时为四元素环和五元素链）的不分离率显著高于纯合子和简单罗伯逊杂合子。然而，至少在形成RIV的杂种情况下，不分离频率增加并非由于杂合复合体的错误分离。在超倍体铺片中发现的额外元件最常见的是近端着丝粒，它们不可能起源于完全中着丝粒的多价体。复合杂合子的另一个特征是在终变期I观察到的单价体频率较高。然而，单价体并非起源于复合构型，复合构型通常每条染色体臂有一个交叉，规则形成。因此，我们推测细胞中多价体的存在会影响减数分裂I时其他元件的配对和分离。
