Ribes E, Sanchez De Romero L D, Kasinsky H E, del Valle L, Giménez-Bonafé P, Chiva M
Departament de Biologia Cel.lular Animal i Vegetal, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
J Exp Zool. 2001 Apr 15;289(5):304-16. doi: 10.1002/1097-010x(20010415/30)289:5<304::aid-jez4>3.0.co;2-d.
Thais is a cenogastropod mollusc belonging to the Muricidae family. The sperm nuclear morphogenesis of Thais develops in two well-defined and peculiar steps. In the first one, the round early spermatidyl nucleus is penetrated by an endonuclear channel, which arranges as a helix at the inner nuclear surface and organizes the condensing chromatin all around. In the second step, the spiral channel stretches, dragging along the associated chromatin and leading to a definitive cylinder-shaped sperm nucleus. Simultaneously with these changes in nuclear shape, the chromatin is sequentially organized in granules, fibres, lamellae, and, finally, in a very condensed structure, whereas the spermiogenic DNA-associated proteins become more basic and simple. The sperm nucleus contains a small group of protamines consisting of only four types of amino acid (lysine, arginine, glycine, and serine). The most remarkable fact on nuclear spermiogenesis in Thais is that, whereas the chromatin condensation process, the nuclear proteins, and the final shape of sperm nucleus are very similar to those in other muricidae studied, the pathway of nuclear morphogenesis is completely different. We propose an independent genetic control for those two spermiogenic events (chromatin condensation and nucleomorphogenesis). Finally we discuss briefly the main traits of nucleomorphogenesis of muricid molluscs.
荔枝螺是一种属于骨螺科的海洋腹足纲软体动物。荔枝螺精子核形态发生经历两个明确且独特的阶段。在第一阶段，圆形的早期精子细胞核被一个核内通道穿透，该通道在内核表面呈螺旋状排列，并使周围的染色质凝聚。在第二阶段，螺旋通道伸展，带动相关染色质，最终形成确定的圆柱状精子细胞核。在核形态发生这些变化的同时，染色质依次组装成颗粒、纤维、薄片，最终形成高度凝聚的结构，而生精过程中与DNA相关的蛋白质变得更具碱性且更简单。精子细胞核包含一小群鱼精蛋白，仅由四种氨基酸（赖氨酸、精氨酸、甘氨酸和丝氨酸）组成。荔枝螺核精子发生最显著的事实是，尽管染色质凝聚过程、核蛋白以及精子细胞核的最终形态与其他已研究的骨螺科动物非常相似，但核形态发生的途径却完全不同。我们提出这两个生精事件（染色质凝聚和核形态发生）受独立的基因控制。最后，我们简要讨论了骨螺科软体动物核形态发生的主要特征。
