Segment number threshold determines juvenile onset of germline cluster expansion in Platynereis dumerilii.
Segment number threshold determines juvenile onset of germline cluster expansion in Platynereis dumerilii.
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DOI：
10.1002/jez.b.23100
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发表时间：
2022-06
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性特征的发育和配子的产生与生长密切相关。Platynereis dumerilii是一种海洋环节动物，已被用于研究生殖系发育和配子发生。杜氏疟原虫在蠕虫体内有生殖细胞簇，这些生殖细胞簇最终形成配子。与其他分节蠕虫一样，杜氏原甲虫的生长是通过在其后端添加新的节段来实现的。片段的数量反映了蠕虫的生长状态，因此是研究生长-繁殖串扰的有用且可测量的生长状态度量。为了了解生长与配子发生进展的相关性，我们研究了几个发育阶段的种系发育。我们发现了一个明显的过渡期，当蠕虫在一个特定的节段数阈值的生殖细胞群的数量增加。此外，我们发现，通过操纵环境条件或通过截肢，保持蠕虫的片段数短，支持种系发育的片段数阈值要求。最后，我们询问这些簇在P. dumerilii中是否在再生中发挥作用（因为在Hydra和Planarian再生中观察到类似的自由漫游细胞），并发现这些簇在P. dumerilii中不需要再生，表明严格的种系性质。总体而言，这些分子分析表明，以前未确定的发育过渡依赖于青少年P. dumerilii的生长状态，导致生殖系扩增大幅增加。总体节数预测的状态，生殖细胞的发展和生殖细胞群的丰富度在Platynereis dumerilii。改变环境条件或切除蠕虫不会改变生殖系发育所需的片段数阈值。表达vasa的胚芽簇在Platynereis dumerilii中的再生不需要。
Development of sexual characters and generation of gametes are tightly coupled with growth. Platynereis dumerilii is a marine annelid that has been used to study germline development and gametogenesis. P. dumerilii has germ cell clusters found across the body in the juvenile worms, and the clusters eventually form the gametes. Like other segmented worms, P. dumerilii grows by adding new segments at its posterior end. The number of segments reflect the growth state of the worms and therefore is a useful and measurable growth state metric to study the growth‐reproduction crosstalk. To understand how growth correlates with progression of gametogenesis, we investigated germline development across several developmental stages. We discovered a distinct transition period when worms increase the number of germline clusters at a particular segment number threshold. Additionally, we found that keeping worms short in segment number, by manipulating environmental conditions or via amputations, supported a segment number threshold requirement for germline development. Finally, we asked if these clusters in P. dumerilii play a role in regeneration (as similar free‐roaming cells are observed in Hydra and planarian regeneration) and found that the clusters were not required for regeneration in P. dumerilii, suggesting a strictly germline nature. Overall, these molecular analyses suggest a previously unidentified developmental transition dependent on the growth state of juvenile P. dumerilii leading to substantially increased germline expansion. Total segment number predicts the state of germline development and the abundance of germline clusters in Platynereis dumerilii. Changing environmental conditions or amputating worms do not alter the segment number threshold requirement for germline development. The vasa‐expressing germ clusters are not required for regeneration in Platynereis dumerilii.