Sperm Chemotaxis in Ascidians
Sperm Chemotaxis in Ascidians
复制标题
海鞘中的精子趋化性
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
Richard L. Miller
中科院分区：
文献类型：
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作者：
Richard L. Miller
概要。海鞘类中的精子趋化性首先在玻璃海鞘属和海鞘属中得到证实，随后在海鞘属、盐萼海鞘属、龟体海鞘属、梨海鞘属、科雷利亚属和Boltenia属中也发现了精子趋化性。物种特异性在许多情况下存在，但与刺胞动物不同，低水平的交叉特异性更为普遍。这在stolidobranchs中尤其如此。玻璃海鞘的精子引诱剂是一种小分子，带负电荷，对热和链霉蛋白酶稳定;它能与玻璃表面紧密结合。钙是海鞘和刺胞动物精子趋化所必需的。
转动发生的机制可能涉及两个收缩的pericentriolar过程臂，以改变轴的fiagellum相对于头部，并产生不对称波的fiagellum。水螅虫和海鞘精子表现出这两种行为的方面，但刺胞动物精子，已知拥有一个大的不对称的pericentriolar过程，显示较少的鞭毛轴和更显着的fiagellar不对称性比海鞘精子，广泛的pericentriolar复合体尚未被证明。鞭毛行为的这些差异可能是对精子头部形状的物种差异的适应。它们似乎延长了转向机动，与一些单细胞鞭毛虫中的突然转向相反。更多关于海鞘精子鞭毛行为的数据将为阐明趋化转向机制提供有价值的工具。
SYNOPSIS. Sperm chemotaxis in ascidians, first demonstrated in the genera Ciona and Styela, has also been found in the genera Ascidia, Halocynthia, Chelyosoma, Pyura, Corella and Boltenia . Species—specificity exists in many cases, but unlike the Cnidaria, low level cross-specificity is more general. This is particularly true in the stolidobranchs. The sperm attractant of Ciona is a small molecule that is negatively charged and stable to heat and pronase; it binds avidly to glass surfaces. Calcium is required for sperm chemotaxis of both ascidian and cnidarian sperm.
The mechanism by which turning occurs may involve both contraction of the pericentriolar process arms to shift the axis of the fiagellum relative to that of the head, and generation of asymmetric waves in the fiagellum. Hydrozoan and ascidian sperm show aspects of both behaviors, but the cnidarian sperm, known to possess a large asymmetric pericentriolar process, shows less shift of the flagelluni axis and more dramatic fiagellar asymmetry than the ascidian sperm, where an extensive pericentriolar complex has yet to be demonstrated. These differences in flagellar behavior may be adaptations to species' differences in the shape of the sperm head. They appear to prolong the turning maneuver, in contrast to the sudden turning seen in some unicellular flagellates. More data on flagellar behavior in ascidian sperm will be a valuable tool for the elucidation of the mechanism of chemotactic turning.