Genes, evolution and molecular ecological studies on avian sex chromosomes

(1)重复DNA家族与鸡卵母细胞灯刷染色体上染色粒的关系：在大多数鸡种的W染色体上，约65%的区域由Xhol家族和EcoRI家族的重复序列组成。另一方面，Fayoumi和埃及品种的W染色体包含约六分之一的Xhol家族序列。在鸡群体中，EcoRI家族有两种类型：高重复型和低重复型。当来自含有不同量Xhol或EcoRI家族序列的品种或个体的灯刷染色体用Xhol家族和EcoRI家族探针进行荧光原位杂交时，每个家族序列定位于不同的染色粒上;由Xhol家族序列组成的染色粒-3在Fayoumi中非常小，低重复型样品中未检测到由EcoRI家族序列组成的染色粒-1。这些结果表明，一个特定的重复序列， 关于我们 该家族在灯刷染色体上形成了一个特殊的染色粒。(2)鸡的DMRT 1基因：在人类中，DMRT 1基因位于9号染色体上。该基因被认为与人类的男性分化有关，因为它的突变经常导致XY男性的女性表型。在鸡中，DMRT 1基因位于Z染色体上，其在雌性中的表达受到很大程度的抑制。我们发现，MHM区域是非常接近的DMRT 1基因在鸡的Z染色体上。MHM区域由BamHl 2.2kb序列的重复序列组成，并且在雌性中被活跃地转录。在男性中，该区域在两条Z染色体上高度甲基化并且转录不活跃。MHM区域的转录物在转录位点积累，即，在雌性鸡的细胞核中与DMRT 1基因非常接近。我们推测MHM转录本的积累可能导致女性细胞核中DMRT 1基因表达的抑制。(3)鸡W染色体上的Wpkci基因：我们发现PKCI（蛋白激酶C相互作用蛋白）基因位于鸡的Z染色体上，而PKCI改变形式的基因（命名为Wpkci）位于W染色体上。在鸡胚成纤维细胞中表达的GFP融合形式的Wpkci位于细胞核中。推测Wpkci可能通过与PKCI形成异源二聚体而抑制PKCI的功能，从而引起雌性发育。少

(1) Relationship between repetitive DNA families and chromomeres on the lampbrush chromosomes from a chicken oocyte : About 65% region of the W chromosome of most breeds of chicken consists of Xhol family and EcoRI family repetitive sequences. On the other hand, the W chromosome of Fayoumi, and Egyptian breed, contains about one-sixth amount of the Xhol family sequence. Among the chicken population, there are two types of EcoRI family : high repetition type and low repetition type. When lampbrush chromosomes from breeds or individuals containing different amounts of Xhol or EcoRI family sequence, were subjected to fluorescence in situ hybridization with Xhol family and EcoRI family probes, each family sequence was localized on a different chromomere ; the chromomere-3 consisting of Xhol-family sequence was very small in Fayoumi, and the chromomere-1 consisting of EcoRI family sequence was undetectable in the low repetition type sample. These results suggested that one particular repeti … More tive family formed a particular chromomere on the lampbrush chromosome.(2) DMRT1 gene of chickens : In human, DMRT1 gene is located on the chromosome No. 9. This gene has been suggested to be involved in the male differentiation in human, because its mutation frequently causes a female phenotype in the XY male. In chickens, DMRT1 gene is located on the Z chromosome and its expression in the female is largely suppressed. We found that the MHM region is very closely located to the DMRT1 gene on the Z chromosome of chickens. The MHM region consists of repeats of a BamHl 2.2 kb sequence and is transcribed actively in the female. In the male, this region is highly methylated and transcriptionally inactive on both of the Z chromosome. The transcripts of the MHM region accumulated at the site of transcription, I.e., in close vicinity to the DMRT1 gene in the nucleus of the female chicken. We speculate that the accumulation of the MHM transcripts may cause suppression of the DMRT1 gene expression in the female nucleus.(3) Wpkci gene on the chicken W chromosome : We found that the PKCI (protein kinase C interacting protein) gene was located on the Z chromosome in chickens and the gene for an altered form of PKCI, designated Wpkci, was located on the W chromosome. The GFP-fusion form of Wpkci, expressed in the chicken embryonic fibroblast, was located in the nucleus. It is speculated that Wpkci may inhibit the function of PKCI by forming a heterodimer with PKCI and thereby causes the female development. Less