Structure and Function of Proteins Involved in the Formation of Supra-Structure of Chromatin in Animals

1)鸡W-异色体结构：鸡W染色体中约60%的DNA由xhoi家族重复序列组成。结果发现，W染色体上10-30%的DNA由另一个重复家族组成，即ecori家族。对ecori家族的1.2kb重复单元进行了克隆和测序。虽然总体序列相似性为68%，但它们的序列组织、基因组高水平甲基化和强弯曲构象彼此非常相似。在鸡细胞核中发现了与这两个弯曲重复序列具有高亲和力结合的蛋白组分，并对其进行了部分纯化。2)丝素h链基因染色质结构失活：丝素h链基因转录在第5龄丝腺中部和第4期丝腺后部失活。当从这些失活组织中分离出来的细胞核用相对高浓度的DNaseI消化时，h链基因染色质产生了规则的DNA片段，这很可能是由于核小体沿着丝蛋白h链中“结晶”区域对应的重复DNA序列进行阶段性排列造成的。

1) Structure of W-heterochromatic body of chicken : About 60% of DNA in the chicken W chromosome has been shown to consist of XhoI-family repetitive sequences. It was found that 10-30% of the DNA in the W chromosome consisted of another repetitive family, EcoRI-family. The 1.2kb repeating unit of the EcoRI-family was cloned and sequenced. Although overall sequence similarity was 68%, their sequence organizations, high level methylation in the genome, and strongly bent conformation were vety similar each other. Protein components showing high affinity binding to these two bent-repetitive sequences were found in the chicken nuclei and were purified partially.2) Inactive chromatin structure of fibroin H-chain gene : Transcription of fibroin H-chain gene is inactive in the 5th-instar middle silk gland and in the 4th-molting stage posterior silk gland. When isolated nuclei from these inactive tissues were digested with DNaseI at relatively high concentration, the H-chain gene chromatin produced regular patterns of DNA fragments, which was most likely caused by phased nuclesomal arrangement along the repetitive DNA sequences corresponding to the "crystalline" regions in fibroin H-chain.