Flatworm stem cells and the germ line: Developmental and evolutionary implications of macvasa expression in Macrostomum lignano
- 作者：Daniela Pfister ; Katrien De Mulder ; Volker Hartenstein ; Georg Kuales ; Gaetan Borgonie ; Florentine Marx ; Joshua Morris ; Peter Ladurner
- 关键词：Germline ; Evolution ; Neoblasts ; Planaria ; Totipotent ; Vasa
- 刊名：Developmental Biology
- 出版年：2008
- 期刊代码：167_00121606
- 类别：bio
- 出版时间：1 July 2008
- 卷：319
- 期：1
- 页码：146-159
- 文件大小：4417 K
摘要
We have isolated and identified the vasa homologue macvasa, expressed in testes, ovaries, eggs and somatic stem cells of the flatworm Macrostomum lignano. Molecular tools such as in situ hybridization and RNA interference were developed for M. lignano to study gene expression and function. Macvasa expression was followed during postembryonic development, regeneration and in starvation experiments. We were able to follow gonad formation in juveniles and the reformation of gonads from stem cells after amputation by in situ hybridization and a specific Macvasa antibody. Expression of macvasa in the germ cells was highly affected by feeding conditions and correlated with the decrease and regrowth of the gonads. RNA interference showed specific down-regulation of macvasa mRNA and protein. The absence of Macvasa did not influence gonad formation and stem cell proliferation. Our results corroborate the exclusive nature of the flatworm stem cell system but challenge the concept of a solely postembryonic specification of the germ line in Platyhelminthes. We address the transition of somatic stem cells to germ cells and speculate on Macrostomum as a system to unravel the mechanisms of preformation or epigenesis in the evolution of germ line specification from somatic stem cells.