COMP-1 promotes competitive advantage of nematode sperm.
COMP-1 promotes competitive advantage of nematode sperm.
复制标题
DOI：
10.7554/elife.05423
复制
发表时间：
2015-03-19
期刊：
影响因子：
7.7
通讯作者：
Stanfield GM
中科院分区：
文献类型：
--
作者：
Hansen JM;Chavez DR;Stanfield GM
精子之间的竞争使卵母细胞受精是有性生殖的普遍特征，也是性选择的一个非常重要的方面。然而，人们对精子用于获得竞争优势的细胞机制以及这些机制如何在遗传上受到调节知之甚少。在这项研究中，我们利用正向遗传筛选秀丽隐杆线虫，以确定一个基因，comp-1，其功能是专门需要在竞争环境中。我们发现，comp-1在精子中的功能，以调节他们的迁移和生殖道内的定位，从而促进他们获得卵母细胞。与先前描述的模型相反，comp-1突变精子在尺寸或速度上没有缺陷，从而定义了一种新的优先使用途径。我们的研究结果表明，不仅精子的功能性状可以影响精子竞争的结果，而且这些性状可以调制的上下文依赖的方式取决于竞争精子的存在。http://dx.doi.org/10.7554/eLife.05423.001孔雀华丽的羽毛和雄鹿的鹿角都是进化而来的特征，因为它们帮助雄性在竞争中战胜对手，与更多的雌性交配。类似地，在一个雌性与多个雄性交配的物种中，如果一个雄性的精子能战胜其他雄性的精子，使雌性的卵子受精，那么他就能提高繁殖成功率。雄性试图获得竞争优势的一种方法是产生大量的精子。然而，雄性也有可能通过产生更高质量的精子来竞争，例如，更善于通过生殖道迁移的细胞。一种叫做秀丽隐杆线虫的显微镜下的蠕虫经常被用来研究精子竞争。每只蠕虫都是雌雄同体或雄性;雌雄同体将精子储存在一个储存结构中，稍后用它使自己的卵子受精。然而，如果一个雌雄同体的人与一个男性交配，男性的精子取代了雌雄同体的精子，并使卵子受精。男性的精子被认为比雌雄同体的精子更有竞争力，因为它们更大，更快，但最近的研究结果表明了一个更复杂的情况。汉森等人发现了一种导致男性C.精子细胞失去了竞争优势。在一个名为comp-1的基因中发生突变的雄性蠕虫产生的精子细胞大小正常，但无法与来自非突变雌雄同体的精子竞争。虽然来自comp-1突变雄性的精子细胞可以在其他精子不存在的情况下通过生殖道迁移并使卵子受精，但在竞争的情况下，突变精子细胞难以迁移，并且通常不存在于雌雄同体的精子储存结构中。因此，它们不再与它们试图受精的卵子接触。来自雌雄同体comp-1突变体的精子细胞也有类似的缺陷;但当comp-1突变雄性与comp-1突变雌雄同体交配时，突变雄性精子重新获得受精优势。comp-1基因的鉴定为环境线索和遗传编码特征的复杂网络提供了一个预览，这些特征影响哪些精子细胞最有可能使卵细胞受精，从而在下一代中存活。DOI：http://dx.doi.org/10.7554/eLife.05423.002网站
Competition among sperm to fertilize oocytes is a ubiquitous feature of sexual reproduction as well as a profoundly important aspect of sexual selection. However, little is known about the cellular mechanisms sperm use to gain competitive advantage or how these mechanisms are regulated genetically. In this study, we utilize a forward genetic screen in Caenorhabditis elegans to identify a gene, comp-1, whose function is specifically required in competitive contexts. We show that comp-1 functions in sperm to modulate their migration through and localization within the reproductive tract, thereby promoting their access to oocytes. Contrary to previously described models, comp-1 mutant sperm show no defects in size or velocity, thereby defining a novel pathway for preferential usage. Our results indicate not only that sperm functional traits can influence the outcome of sperm competition, but also that these traits can be modulated in a context-dependent manner depending on the presence of competing sperm. DOI: http://dx.doi.org/10.7554/eLife.05423.001 The ornate feathers of a peacock and the antlers of a stag are both traits that have evolved because they help a male to outcompete his rivals and mate with more females. Similarly, in species where each female mates with multiple males, a male can improve his reproductive success if his sperm outcompetes the other males' sperm and fertilizes the female's eggs. One way that males try to gain a competitive edge is by producing large quantities of sperm. However, it is also possible that males could compete by generating higher-quality sperm, for example, cells that are better at migrating through the reproductive tract. A microscopic worm called Caenorhabditis elegans is often used to investigate sperm competition. Each worm is either a hermaphrodite or a male; and hermaphrodites store their sperm within a storage structure and use it later to fertilize their own eggs. However, if a hermaphrodite mates with a male, the male's sperm displaces the hermaphrodite's stored sperm and fertilizes the eggs instead. The male's sperm cells were thought to be more competitive because they are larger and faster than the hermaphrodite's sperm, but recent findings suggest a more complex scenario. Hansen et al. identified a genetic mutation that causes male C. elegans sperm cells to lose their competitive advantage. Male worms with a mutation in a gene called comp-1 produce sperm cells that are normal in size, but that cannot outcompete sperm from a non-mutant hermaphrodite. Although sperm cells from a comp-1 mutant male can migrate through the reproductive tract and fertilize eggs when other sperm are not present, in competitive situations the mutant sperm cells have difficulties migrating and are often absent from the hermaphrodite's sperm storage structure. Thus, they no longer come into contact with the eggs that they seek to fertilize. Sperm cells from hermaphrodite comp-1 mutants have similar defects; but when a comp-1 mutant male mates with a comp-1 mutant hermaphrodite, the mutant male sperm regains its fertilization advantage. The identification of the comp-1 gene provides a preview into a complex network of environmental cues and genetically encoded traits that influence which sperm cells are most likely to fertilize an egg cell, and thus live on in the next generation. DOI: http://dx.doi.org/10.7554/eLife.05423.002