TESTIS-SPECIFIC HISTONES AND MRNA DURING SPERMATOGENESIS

精子发生涉及前体细胞的顺序变化 单倍体精子通过调节有丝分裂、减数分裂和 生精细胞分化事件。在减数分裂过程中， 体细胞组蛋白被生精细胞特异性取代 组蛋白。此应用程序的主要目标是 研究体细胞和睾丸特异性组蛋白基因的调控 以及睾丸特异组蛋白在新细胞组装中的作用 精子发生过程中的染色质结构和减数分裂。这个 生精细胞特异性转录的相反机制 和S期特异转录元件的抑制作用。 睾丸特异的组蛋白TH2 B基因将通过 确定细胞所需的DNA序列元素- 核因子的特异性转录和结合部位 监管要素。DNA元素将是 通过顺序删除5‘或3’侧翼来识别 TH2B基因序列与报告基因融合， 氯霉素乙酰转移酶(CAT)。CAT在不同环境中的表达 对TH2 B调控序列的控制将通过 将融合基因导入大鼠生精细胞。这个 TH2 B基因具有允许基因表达的DNA元件(S 以特定于细胞周期的方式，但元件被抑制在 这些细胞。将对抑制的机制进行调查。这个 睾丸特异性组蛋白在新染色质组装中的作用 通过引入大鼠H_2B来研究结构和减数分裂 和TH2 B基因导入不产生H 2B组蛋白的酵母中。 改变H_2B结合的TH_2B的氨基酸序列 将确定组蛋白与DNA的比例。大鼠H1和TH1组蛋白基因 H1+H2B和TH1+TH2B基因的组合也将是 将组蛋白导入酵母细胞研究组蛋白的作用 关于染色质结构和减数分裂。我们将对H2A基因进行测序 在TH2B基因的3‘端确定组蛋白基因是否 编码睾丸特异的H2 A组蛋白。

Spermatogenesis involves sequential changes of precursor cells to haploid spermatozoa through regulated mitotic, meiotic, and spermiogenic cell differentiation events. During meiotic process, somatic histones are replaced by spermatogenic cell-specific histones. The major objective of this application is to investigate regulation of somatic and testis-specific histone genes and also the role of testis-specific histones in assembly of new chromatin structure and meiosis during spermatogenesis. The opposing mechanisms of spermatogenic cell-specific transcription and repression of S-phase specific transcription elements in a testis-specific histone TH2B gene will be investigated by determining the DNA sequence elements required for the cell- specific transcription and the binding sites of nuclear factors on the regulatory elements. The DNA elements will be identified by sequential deletions of the 5' or 3' flanking sequence of the TH2B gene fused with a reporter gene, chloramphenicol acetyl transferase (CAT). Expression of CAT under the control of TH2B regulatory sequences will be examined by introduction of the fused genes into rat spermatogenic cells. The TH2B gene has the DNA element(s) which allows the gene expressed in a cell-cycle specific manner but the elements are repressed in the cells. The mechanism of repression will be investigated. The role of testis-specific histones in assembly of new chromatin structure and meiosis will be investigated by introducing rat H2B and TH2B genes into the yeast which do not produce H2B histones. The amino acid sequences of TH2B which alter the binding of H2B histones to DNA will be determined. Rat H1 and TH1 histone genes and also combination of H1 + H2B and TH1 + TH2B genes will be introduced into yeast cells to investigate effects of the histones on chromatin structure and meiosis. We will sequence the H2A gene on the 3' side of TH2B gene to determine if the histone gene encodes the testis-specific H2A histones.