Pigozzi M I
Instituto de Investigaciones en Reproducción, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
Cytogenet Genome Res. 2007;119(1-2):105-12. doi: 10.1159/000109626. Epub 2007 Dec 14.
Synaptonemal complex (SC) spreads from bird oocytes and spermatocytes show the complete chromosome complement and can be observed at the light microscope using immunostaining of the proteins that compose the lateral elements. To investigate the use of avian SC spreads as substrates for fluorescent in situ hybridization (FISH) in combination with immunostaining, we applied two single-copy sequences to chicken oocyte spreads. Signals for both target sequences were consistently observed on the short arm of bivalent 1 in a large number of nuclei. Based on previous data about the size of chromosome 1 and from measurements on probed SC spreads, an estimate of the physical distance in Mb between each sequence and the telomere was calculated. The crossover frequencies along SC 1 obtained by immunolocalization of MLH1 foci during pachytene were used to calculate the distances in cM to the target sequences and to compare this cytogenetic SC map with the consensus linkage map for GGA1. The combination of SC-FISH and immunostaining could be generally applied to obtain high-resolution mapping of single-copy sequences in birds and, coupled with MLH1 crossover maps, it could be a reliable approach to obtain genetic distances between markers to test the genetic linkage maps generated from molecular markers.
联会复合体（SC）铺片可从鸟类卵母细胞和精母细胞中获得，其显示出完整的染色体组型，并且可以通过对构成侧生元件的蛋白质进行免疫染色，在光学显微镜下观察到。为了研究鸟类SC铺片作为荧光原位杂交（FISH）底物并结合免疫染色的用途，我们将两个单拷贝序列应用于鸡的卵母细胞铺片。在大量细胞核中，均在二价体1的短臂上一致观察到两个靶序列的信号。根据先前关于1号染色体大小的数据以及对探测的SC铺片的测量结果，计算了每个序列与端粒之间以兆碱基（Mb）为单位的物理距离。通过在粗线期对MLH1灶进行免疫定位获得的沿SC 1的交叉频率，用于计算到靶序列的厘摩（cM）距离，并将此细胞遗传学SC图谱与GGA1的共识连锁图谱进行比较。SC-FISH和免疫染色的组合通常可用于获得鸟类单拷贝序列的高分辨率图谱，并且与MLH1交叉图谱相结合，它可能是一种可靠的方法，可用于获得标记之间的遗传距离，以测试由分子标记生成的遗传连锁图谱。
