An ancient split of germline and somatic stem cell lineages in Hydra

Abstract

In many animals, germ cell segregation occurs during early embryogenesis to protect the genome, but its origin in basal metazoans is controversial. Here, we show in the freshwater polyp Hydra by clonal analysis and transgenic animals that interstitial stem cells comprise two separate stem cell populations, i.e., germline and multipotent somatic stem cells. We isolated genetically labelled stem cells for a global transcriptome study and discovered a broad set of germline-specific/enriched genes including Prdm9, Pax5, Dmrt1. In an alternative splicing analysis, we identified many genes with germline-specific isoforms; among them, male-specific isoforms of Dmrt1 and Snf5. The somatic interstitial stem cell lineage was characterized by numerous neuronal control genes like Neurog. But all stem cells in Hydra also share a core of stemness genes that has its roots in unicellular eukaryotes. This suggests an evolutionary scenario in which, at the emergence of animal multicellularity, there was an early split into a stable germline and different somatic stem cell lineages.

Sex change every year: A unique reproductive strategy of the stony coral,Fimbriaphyllia(Euphyllia)ancora

“…The same applies to the change from female to male. In Hydra , molecular markers for female GSCs and male GSCs have been identified (28, 29). In our previous study, we have identified GCS-like cells in gonads of F. ancora (30).…”

A whole-body atlas of non-graded BMP signaling activity in a sea anemone

“…Hydrozoan i-cells constitute a pool of pluri-or multipotent stem cells that contributes to somatic cells and the germline (Bosch & David, 1987;Holstein, 2023;Houliston et al, 2010;Muller et al, 2004;Varley et al, 2023). In Hydra, Northern hybridization of smad1/5 indicated that it is upregulated in i-cells (Hobmayer et al, 2001), while transcriptomic analysis showed the upregulation of the BMP receptor actr1 in multipotent interstitial cells and smad1/5 and BMP antagonist dand in germline stem cells (Nishimiya-Fujisawa et al, 2023). In Hydractinia, the expression a putative bmp receptor has been detected in developing oocytes and the male gonophore gastrodermis (Sanders et al, 2014).…”