Gustavsson I, Switoński M, Iannuzzi I, Plöen L, Larsson K
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala.
Cytogenet Cell Genet. 1989;50(4):188-94. doi: 10.1159/000132772.
In a litter of nine domestic pigs, a translocation between the X-chromosome and chromosome 13 was found in six individuals: four males and two females. The translocation was presumed to have originated in the dam. Banding studies indicated that the breaks preceding the translocation had occurred in a distal GTG-negative band of the long arm of the X, 15-30% of the length of Xq from the telomere, and proximally in chromosome 13, 15-25% from the centromere. The normal X of the females invariably replicated its DNA late. Synaptonemal complex analysis of spermatocytes demonstrated a quadrivalent in 75 of 85 analyzable cells (88.2%), and in 10 cells (11.8%) one trivalent and one univalent were found. Extensive nonhomologous pairings were visualized in the pachytene stage by applying an 'overlap' test measuring the sex chromosomes and collating their pairings. An arrest in male meiosis was verified histologically; no meiotic stages later than pachytene developed. This resulted in sterility, with considerable testicular hypoplasia. The records of female fertility were available only for the dam and did not show any deviations from the average of the herd.
在一窝9头家猪中，发现6头个体（4头雄性和2头雌性）的X染色体与13号染色体之间发生了易位。推测该易位起源于母猪。染色体显带研究表明，易位前的断裂发生在X染色体长臂的一个远端GTG阴性带，距端粒为Xq长度的15 - 30%，在13号染色体上则近端发生在距着丝粒15 - 25%处。雌性的正常X染色体总是在DNA复制后期进行复制。对精母细胞的联会复合体分析显示，在85个可分析细胞中有75个（88.2%）出现四价体，在10个细胞（11.8%）中发现一个三价体和一个单价体。通过应用测量性染色体并整理其配对情况的“重叠”试验，在粗线期观察到广泛的非同源配对。组织学检查证实雄性减数分裂停滞；没有发育到粗线期之后的减数分裂阶段。这导致了不育，并伴有相当程度的睾丸发育不全。关于雌性生育力的记录仅来自母猪，未显示出与猪群平均水平有任何偏差。
