Studies on the biological significance of the spiral architecture of sperms of plants assigned to the land-plant lineage.

本研究旨在探讨精子螺旋结构在陆地植物有性生殖中的生物学意义。(1)属于陆地植物进化谱系的植物产生的所有精子，无论是在外部结构上还是在细胞内组织上，或两者兼而有之，基本上都是螺旋的。最具卵性的特征是精细胞体卷曲流线型，细胞体表面鞭毛呈螺旋状排列。内鞭毛精子反映在各种细胞器的胞内排列上，包括细胞核、前部巨大线粒体和基本小体。(2)轮藻、苔藓和少数石蕊类植物产生双鞭毛精液。在双鞭毛精子中，两个鞭毛位于细胞的前部，它们的基体略低于细胞顶端，从而导致细胞结构的不对称轮廓。两个基体体…与其他光合作用生物的精子相比，更多的精子是单形和平行的，由前到后交错排列。(3)大多数蕨类植物和少数裸子植物中存在多鞭毛精子，包括银杏和苏铁。在多鞭毛精子中，鞭毛及其基体呈螺旋状排列，排列成几排。从前面看，细胞体向左卷曲。(4)具有这种结构特征的精子只具有螺旋向前游动的能力，而不像其他进化谱系的绿藻种群那样具有向后游动的能力。(5)在颈卵器受精过程中，体部卷曲的结构和鞭毛的螺旋排列可能有效地向下钻过颈卵器的颈部和腹管，但这些形态特征在一些轮藻包括鞘毛虫、克雷伯氏菌等的雄配子中的意义尚不确定。较少

This project was conducted to evaluate the biological significance of the spiral architecture of sperms in sexual reproduction of plants which are assigned to the land-plant lineage.(1) All sperms produced by plants belonging to the land-plant evolutional lineage are fundamentally spiral either in their external architecture or intracellular organization, or both. The most ovbious features are found in their coiled streamlined body of sperm cell and spiral arrangement of flagella on the surface of cell body. The internal ones are reflected on the intracellular arrangement of various cell organelles, including cell nucleus, anterior giant mitochondrion, and basal bodies.(2) Biflagellate sperms are produced in charophytes, mosses, liverworts, and a few lycophytes.. In biflagellate sperms two flagella are inserted at the cell anterior and their basal bodies are positioned slightly downward from the cell tip, thus resulting in an asymmetrical profile of cell architecture. Two basal bodies … More are monomorphic and parallel, staggered in an anterior to posterior fashion in contrast to those of sperms of other photosynthetic organisms.(3) Multiflagellated sperms are found in most ferns and a few gymnosperms, including Ginkgo and cycads. In multiflagellated sperms flagella and their basal bodies are arranged in spiral fashion with several rows. The cell body coils to the left when viewed from the anterior. Basal bodies are distributed on the MLS in different manners, indicating the difference of their role in swimming movement.(4) The sperm that have such structural features only swimm forward in spiral fashion, but does not have ability of back-swimming to avoid material as those of green algal swarmers of other evolutionary lineages.(5) The coiled structure of body and spiral arrangement of flagella may effectively work to drill down through the neck and ventral canals of the archegonium in the archegoniate fertilization, but significance of these morphological characteristics in male gametes of some charophytes, including Coleochaete, Klebsormidium, is uncertain. Less