Biology subjects

Garschall, K.

Publications and source records attributed to Garschall, K..

3 recordsLinked to original sources

bioRxiv2025

Nutritional regulation of cellular quiescence depth and cell cycle re-entry in Vasa2+/Piwi1+ cells in a sea anemone

Animals with lifelong growth adjust their growth rates to nutrient availability, yet the underlying cellular and molecular mechanisms remain poorly understood. Here, we studied how food supply and TOR signalling regulate the cell cycle in a multipotent, Vasa2-/Piwi1-expressing cell population in the sea anemone Nematostella vectensis. We discovered that starvation induces a reversible G1/G0 cell cycle arrest in Vasa2+/Piwi1+ cells and that cell cycle re-entry upon refeeding is dependent on TOR signalling. In addition, the length of the refeeding stimulus after starvation determines the proportion of cells that re-enter S-phase. Remarkably, prolonged starvation delayed both refeeding-induced TOR signalling activation and S-phase re-entry. This strongly suggests that Nematostella Vasa2+/Piwi1+ cells undergo starvation-controlled quiescence deepening, previously described only in unicellular eukaryotes and mammalian cell culture. The nutritional control of quiescence and cell proliferation may thus be a fundamental, evolutionarily conserved strategy underlying the environmental regulation of indeterminate growth in animals.

developmental biology↗

bioRxiv2024

The nascent RNA labelling compound 5-ethynyl uridine (EU) integrates into DNA in the sea anemone Nematostella vectensis

BackgroundThe detection of de novo synthesized mRNA transcripts is crucial for understanding the regulation of eukaryotic transcription. Using nucleoside or nucleotide analogues to label nascent RNA is potentially jeopardized by the ubiquitous presence of ribonucleotide reductase enzymes (RNRs) that can convert ribonucleotides into 2-deoxyribonucleotides, the building blocks of DNA. Despite this challenge, the uridine analogue 5-ethynyl uridine (EU) has been commercialized and routinely used as specific label for nascent RNAs. Here, we employ confocal imaging, flow cytometry and biochemistry methods to study the specificity of EU to label RNA in six different animal species. ResultsWe demonstrate that EU integrates as expected predominantly into RNA of human embryonic kidney cell line (HEK293), the Drosophila wing disc and the comb jelly Mnemiopsis leidyi. In contrast, we found that EU predominantly labels DNA in the sea anemones Nematostella vectensis and Exaiptasia diaphana, and the polychaete Platynereis dumerilii. In Nematostella, we show that inhibiting RNR by hydroxyurea abolishes cell proliferation and the incorporation of EU into DNA. Alternative compounds for labelling nascent RNA, such as 5-ethynyl cytidine (EC), 5-ethynyl uridine triphosphate (EUTP) or 2-ethynyl adenosine (EA) show similarly low specificity for RNA in Nematostella. ConclusionsOur findings raise concerns about the specificity of ethynylated nucleosides and nucleotides, including EU, to label RNA in some animals. We therefore suggest good practice guidelines for using EU as an RNA labelling tool and discuss pitfalls and indicators that help identifying unintentional DNA labelling.

cell biology↗

bioRxiv2023

The cellular basis of feeding-dependent body size plasticity in sea anemones

Animals with indeterminate growth can adapt their growth rate and body size to changing food availability throughout their lifetime. As the cellular basis underlying food-dependent growth plasticity is poorly understood, we quantified how the sea anemones Nematostella vectensis and Exaiptasia diaphana (Aiptasia) respond to feeding and starvation on organismal and cellular levels. Using mathematical modelling to analyse growth phases, we found that growth and shrinkage rates in Nematostella are exponential, stereotypic and accompanied by high levels of cell gain or loss, respectively. During starvation and re-feeding, a considerable proportion of juvenile polyp cells (>7%) reversibly shift between S/G2/M and G1/G0 cell cycle phases, suggesting a tight nutritional control of quiescence and cell cycle re-entry. In the facultative symbiotic sea anemone Aiptasia, we found that growth and cell proliferation rates are dependent on the symbiotic state and, in comparison to Nematostella, respond less strongly to changes in food supply. Altogether, we provide a benchmark and resource to study the nutritional regulation of body plasticity on molecular, cellular and genomic levels using the rich functional toolkit available for Nematostella. Summary statementFeeding and starvation in sea anemones induce growth and shrinkage, cell size changes and dynamic cell proliferation changes that support a nutritional control of quiescence and cell cycle re-entry.

developmental biology↗