Biology subjects

Steinmetz, P. R. H.

Publications and source records attributed to Steinmetz, P. R. H..

3 recordsLinked to original sources

bioRxiv2023

An adult stem-like cell population generates germline and neurons in the sea anemone Nematostella vectensis

Most genetic research animals (e.g., vertebrates, insects, nematodes) segregate germline and soma during early embryogenesis. In contrast, some highly regenerative bilaterian (e.g., planarians) and non-bilaterian animals (e.g., hydrozoan cnidarians) retain adult stem cells with both germinal and somatic potentials. As these cells have been studied in only few phyla, their biology and evolution remain mostly enigmatic. Here, we aimed to identify and characterize adult stem cells and their cell lineages in the sea anemone Nematostella vectensis by combining gene expression analysis, immunostainings, and meganuclease-mediated and CRISPR/Cas9-mediated knock-in reporter lines of conserved germline and multipotency genes (e.g., vasa2, piwi1). We found a small population of vasa2+/piwi1+ cells in the gastrodermal folds of juvenile and adult sea anemones that generates germline and a diversity of somatic, mostly proliferative cells. Using a combination of soxB(2) neural progenitor and piwi1 reporter lines, we found that the somatic progeny from vasa2+/piwi1+ cells includes soxB(2)+ neural progenitors. Our results strongly support the existence of an adult Vasa2+/Piwi1+ multipotent stem-like cell population that derives both germline and somatic lineages in Nematostella. The similarities of lineages and gene expression profiles between Nematostella Vasa2+/Piwi1+ stem-like cells and hydrozoan interstitial stem cells support their evolutionary conservation among cnidarians.

developmental biology↗

bioRxiv2022

NvPrdm14d-expressing neural progenitor cells contribute to non-ectodermal neurogenesis in Nematostella vectensis

Neurogenesis has been studied extensively in the ectoderm, from which most animals generate the majority of their neurons. Neurogenesis from non-ectodermal tissue is, in contrast, poorly understood. Here we use the cnidarian Nematostella vectensis as a model to provide new insights into the molecular regulation of non-ectodermal neurogenesis. We show that the transcription factor NvPrdm14d is expressed in a subpopulation of NvSoxB(2)-expressing endodermal progenitor cells and their NvPOU4-expressing progeny. Using a new transgenic reporter line, we show that NvPrdm14d-expressing cells give rise to neurons in the body wall and in close vicinity of the longitudinal retractor muscles. RNA-sequencing of NvPrdm14d::GFP-expressing cells and gene knockdown experiments provide candidate genes for the development and function of these neurons. Together, the identification of a population of endoderm-specific neural progenitor cells and of previously undescribed putative motoneurons in Nematostella provide new insights into the regulation of non-ectodermal neurogenesis.

developmental biology↗

bioRxiv2022

Evolutionary conserved aspects of animal nutrient uptake and transport in sea anemone vitellogenesis

Vitellogenesis, the accumulation of egg yolk, relies on the transport of dietary nutrients from the gut to the ovary through the circulatory system in many bilaterians (e.g. vertebrates, arthropods). How these dietary nutrients and yolk precursors are absorbed and transported in cnidarians (e.g. corals, sea anemones, jellyfish), which are bi-layered and lack a circulatory system, is however only poorly understood. Here, we studied the tissues and molecules that facilitate the uptake and transport of dietary nutrients, especially lipids, towards the oocytes in the sea anemone Nematostella vectensis to better understand the evolution of systemic nutrient transport in animals. We identified the somatic gonad epithelium as one of several gastrodermal tissues specialized in phagocytosis, micropinocytosis and intracellular digestion. We showed more specifically that dietary fatty acids are absorbed by the ApolipoproteinB- and Vitellogenin-expressing somatic gonad epithelium. Their subsequent, rapid transport into the extracellular matrix (ECM) and endocytosis into oocytes is likely mediated by an evolutionary conserved Vitellogenin (Vtg)-Very Low-Density Lipoprotein Receptor (VLDLR) ligand/receptor pair. We propose that ECM-based, Vtg/VLDLR-mediated lipoprotein transport during vitellogenesis predates the cnidarian-bilaterian split and provided a mechanistic basis to evolve sophisticated circulatory systems in bilaterians.

evolutionary biology↗