Kadandale Pavan, Stewart-Michaelis Allison, Gordon Scott, Rubin Jacob, Klancer Richard, Schweinsberg Peter, Grant Barth D, Singson Andrew
Waksman Institute and Department of Genetics, Rutgers University, Piscataway, New Jersey 08854, USA.
Curr Biol. 2005 Dec 20;15(24):2222-9. doi: 10.1016/j.cub.2005.10.043.
The molecular machinery that mediates sperm-egg interactions at fertilization is largely unknown. We identify two partially redundant egg surface LDL receptor repeat-containing proteins (EGG-1 and EGG-2) that are required for Caenorhabditis elegans fertility in hermaphrodites, but not males. Wild-type sperm cannot enter the morphologically normal oocytes produced by hermaphrodites that lack egg-1 and egg-2 function despite direct gamete contact. Furthermore, we find that levels of meiotic maturation/ovulation and sperm migratory behavior are altered in egg-1 mutants. These observations suggest an unexpected regulatory link between fertilization and other events necessary for reproductive success. egg-1 and egg-2 are the result of a gene duplication in the nematode lineage leading to C. elegans. The two closely related species C. briggsae and C. remanei encode only a single egg-1/egg-2 homolog that is required for hermaphrodite/female fertility. In addition to being the first identified egg components of the nematode fertilization machinery, the egg-1 and egg-2 gene duplication could be vital with regards to maximizing C. elegans fecundity and understanding the evolutionary differentiation of molecular function and speciation.
在受精过程中介导精卵相互作用的分子机制在很大程度上尚不清楚。我们鉴定出两种部分冗余的卵表面含低密度脂蛋白受体重复序列的蛋白质（EGG-1和EGG-2），它们是秀丽隐杆线虫雌雄同体生育力所必需的，但对雄性则不是必需的。尽管配子直接接触，但野生型精子无法进入缺乏egg-1和egg-2功能的雌雄同体所产生的形态正常的卵母细胞。此外，我们发现egg-1突变体的减数分裂成熟/排卵水平和精子迁移行为发生了改变。这些观察结果表明受精与生殖成功所需的其他事件之间存在意想不到的调控联系。egg-1和egg-2是线虫谱系中导致秀丽隐杆线虫的基因重复的结果。两个密切相关的物种——briggsae线虫和remanei线虫仅编码一种雌雄同体/雌性生育力所必需的egg-1/egg-2同源物。除了是首次鉴定出线虫受精机制中的卵成分外，egg-1和egg-2基因重复对于最大化秀丽隐杆线虫的繁殖力以及理解分子功能和物种形成的进化分化可能至关重要。
