Texada Michael J, Simonette Rebecca A, Johnson Cassidy B, Deery William J, Beckingham Kathleen M
Department of Biochemistry and Cell Biology, MS-140, Rice University, Houston, TX 77005, USA.
J Cell Sci. 2008 Jun 1;121(11):1926-36. doi: 10.1242/jcs.026559. Epub 2008 May 13.
Males of the genus Drosophila produce sperm of remarkable length. Investigation of giant sperm production in Drosophila melanogaster has demonstrated that specialized actin and microtubule structures play key roles. The gene yuri gagarin (yuri) encodes a novel protein previously identified through its role in gravitaxis. A male-sterile mutation of yuri has revealed roles for Yuri in the functions of the actin and tubulin structures of spermatogenesis. Yuri is a component of the motile actin cones that individualize the spermatids and is essential for their formation. Furthermore, Yuri is required for actin accumulation in the dense complex, a microtubule-rich structure on the sperm nuclei thought to strengthen the nuclei during elongation. In the yuri mutant, late clusters of syncytial nuclei are deformed and disorganized. The basal bodies are also mispositioned on the nuclei, and the association of a specialized structure, the centriolar adjunct (CA), with the basal body is lost. Some of these nuclear defects might underlie a further unexpected abnormality: sperm nuclei occasionally locate to the wrong ends of the spermatid cysts. The structure of the axonemes that grow out from the basal bodies is affected in the yuri mutant, suggesting a possible role for the CA in axoneme formation.
果蝇属的雄性产生长度惊人的精子。对黑腹果蝇巨型精子产生的研究表明，特殊的肌动蛋白和微管结构起着关键作用。尤里·加加林基因（yuri）编码一种先前因其在重力趋性中的作用而被鉴定的新型蛋白质。yuri的雄性不育突变揭示了尤里在精子发生的肌动蛋白和微管蛋白结构功能中的作用。尤里是使精子细胞个体化的能动肌动蛋白锥体的一个组成部分，对其形成至关重要。此外，在致密复合体（一种富含微管的精子核结构，被认为在延长过程中强化细胞核）中肌动蛋白积累需要尤里。在yuri突变体中，合胞体细胞核的晚期簇发生变形且无序排列。基体在细胞核上的定位也错误，并且一种特殊结构——中心粒附属物（CA）与基体的关联丧失。这些核缺陷中的一些可能是另一个意外异常情况的基础：精子核偶尔会定位到精子囊肿的错误末端。从基体长出的轴丝结构在yuri突变体中受到影响，这表明CA在轴丝形成中可能发挥作用。
