Olivares C, Lila Vera M, Ruíz-Lara S
Departamento Biomedico, Universidad de Antofagasta, Chile.
Mol Cell Biochem. 1993 Aug 11;125(1):87-95. doi: 10.1007/BF00926838.
The chromatin of the spermatozoa from the bivalve mollusc Protothaca thaca, has a peculiar composition in which coexist core histones with sperm-specific proteins H1 and Pt1, the latter being a protein exhibiting features intermediate between histones and protamines. In this paper, we report an analysis of chromatin organization using micrococcal nuclease digestion, salt fractionation of soluble chromatin derived from nuclease digestion and crosslinking experiments. The results obtained indicate that it is possible to obtain two types of chromatin, one which is soluble, more accessible to micrococcal nuclease action and which does not contain Pt1, and another insoluble type, more resistant to micrococcal nuclease and enriched in protein Pt1. The crosslinking experiments show that the protein Pt1 interacts with itself and with core histones but not with sperm-specific H1. These results have led us to propose a special structural arrangement for this chromatin. Based in the data reported here we propose the coexistence in the genome of P. thaca of two interspersed chromatin domains, one nucleosomal and the other nonnucleosomal containing protein Pt1.
双壳贝类软体动物原蛤（Protothaca thaca）精子的染色质具有特殊的组成，其中核心组蛋白与精子特异性蛋白H1和Pt1共存，后者是一种表现出介于组蛋白和鱼精蛋白之间特征的蛋白质。在本文中，我们报告了使用微球菌核酸酶消化、核酸酶消化衍生的可溶性染色质的盐分级分离和交联实验对染色质组织的分析。获得的结果表明，可以获得两种类型的染色质，一种是可溶的，更容易受到微球菌核酸酶的作用且不含Pt1，另一种是不溶的类型，对微球菌核酸酶更具抗性且富含蛋白质Pt1。交联实验表明，蛋白质Pt1与自身以及核心组蛋白相互作用，但不与精子特异性H1相互作用。这些结果使我们提出了这种染色质的一种特殊结构排列。基于此处报告的数据，我们提出在原蛤的基因组中存在两个相互穿插的染色质结构域，一个是核小体结构域，另一个是含有蛋白质Pt1的非核小体结构域。
