Bainbridge Rachel E, Rosenbaum Joel C, Sau Paushaly, Carlson Anne E
Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15260.
bioRxiv. 2023 Feb 3:2023.02.02.526858. doi: 10.1101/2023.02.02.526858.
Fertilization of eggs from the African clawed frog is characterized by an increase in cytosolic calcium, a phenomenon that is also observed in other vertebrates such as mammals and birds. During fertilization in mammals and birds, the transfer of the soluble PLCζ from sperm into the egg is thought to trigger the release of calcium from the endoplasmic reticulum (ER). Injecting sperm extracts into eggs reproduces this effect, reinforcing the hypothesis that a sperm factor is responsible for calcium release and egg activation. Remarkably, this occurs even when sperm extracts from are injected into mouse eggs, suggesting that mammals and share a sperm factor. However, lacks an annotated gene, which encodes the PLCζ enzyme. In this study, we attempted to determine whether sperm from express an unannotated ortholog. We identified orthologs in 11 amphibian species, including 5 that had not been previously characterized, but did not find any in either or the closely related . Additionally, we performed RNA sequencing on testes obtained from adult males and did not identify potential PLCZ1 orthologs in our dataset or in previously collected ones. These findings suggest that PLCZ1 may have been lost in the lineage and raise the question of how fertilization triggers calcium release and egg activation in these species.
非洲爪蟾卵的受精以胞质钙增加为特征，这种现象在其他脊椎动物如哺乳动物和鸟类中也能观察到。在哺乳动物和鸟类的受精过程中，可溶性磷脂酶Cζ（PLCζ）从精子转移到卵中被认为会触发内质网（ER）释放钙。将精子提取物注入卵中可重现这种效应，强化了精子因子负责钙释放和卵激活的假说。值得注意的是，即使将[未提及物种名称]的精子提取物注入小鼠卵中，这种情况也会发生，这表明哺乳动物和[未提及物种名称]共享一种精子因子。然而，[未提及物种名称]缺乏一个注释的PLCζ基因，该基因编码PLCζ酶。在本研究中，我们试图确定[未提及物种名称]的精子是否表达未注释的PLCζ直系同源物。我们在11种两栖动物物种中鉴定出了PLCζ直系同源物，包括5种以前未被表征的，但在[未提及物种名称]或其近缘物种中均未发现。此外，我们对成年[未提及物种名称]雄性的睾丸进行了RNA测序，在我们的数据集中或先前收集的数据集中均未鉴定出潜在的PLCZ1直系同源物。这些发现表明PLCZ1可能在[未提及物种名称]谱系中丢失了，并提出了这些物种中受精如何触发钙释放和卵激活的问题。
