シュミット マイケル ヴュルツブルグ大学, 人類遺伝学研究所, 教授
マグレガー ハーバート レスター大学, 動物学科, 教授
ガギンスカヤ エレーナ セントペテルスブルグ州立大学, 生物学研究所, 教授
バーク テリー シェフィールド大学, 動・植物科学科, 教授
|Budget Amount *help
¥5,400,000 (Direct Cost : ¥5,400,000)
Fiscal Year 1999 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1998 : ¥3,100,000 (Direct Cost : ¥3,100,000)
(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
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