Setterfield L A, Mahadevaiah S, Mittwoch U
Department of Genetics and Biometry, University College London, UK.
Cytogenet Cell Genet. 1988;49(4):293-9. doi: 10.1159/000132681.
In adult males carrying the male-fertile reciprocal translocation T(2;4)13H, body weights, testis weights, and sperm counts were higher in heterozygotes than in homozygotes. Heterozygotes whose mothers were C3H/He exceeded their reciprocal counterparts in the same criteria. At 3-4 days of age, no significant differences between homozygous and heterozygous females were found in body weight, ovarian volume, or oocyte numbers, although mean oocyte volumes were somewhat larger in heterozygotes than in homozygotes. In homozygous males and females the synaptonemal complexes of rearranged chromosomes appeared as bivalents that were indistinguishable from normal bivalents. In most gametocytes of heterozygotes, the translocation was present in the form of a quadrivalent. The degree of pairing failure was greater in oocytes than in spermatocytes. Terminal asynapsis of quadrivalents was very rare in spermatocytes, but it affected one quarter of the oocytes. Only very few translocation configurations were associated with the XY bivalent. It is concluded that the number of sperm produced in male heterozygotes can match the general increase in vigor by the formation of a high level of fully paired quadrivalents, whereas a greater degree of terminal asynapsis in the quadrivalents of oocytes may indicate a slightly more deleterious effect of this translocation on oogenesis.
在携带雄性可育相互易位T(2;4)13H的成年雄性中，杂合子的体重、睾丸重量和精子数量均高于纯合子。母亲为C3H/He的杂合子在相同标准下超过了其相应的反交杂合子。在3 - 4日龄时，纯合子和杂合子雌性在体重、卵巢体积或卵母细胞数量上未发现显著差异，尽管杂合子的平均卵母细胞体积略大于纯合子。在纯合子雄性和雌性中，重排染色体的联会复合体呈现为与正常二价体无法区分的二价体。在杂合子的大多数配子细胞中，易位以四价体的形式存在。卵母细胞中的配对失败程度大于精母细胞。四价体的末端不联会在精母细胞中非常罕见，但它影响了四分之一的卵母细胞。只有极少数的易位构型与XY二价体相关。结论是，雄性杂合子产生的精子数量可以通过形成高水平的完全配对四价体来匹配活力的总体增加，而卵母细胞四价体中更高程度的末端不联会可能表明这种易位对卵子发生的有害影响略大。
