Biology subjects

Stockinger, A. W.

Publications and source records attributed to Stockinger, A. W..

5 recordsLinked to original sources

bioRxiv2025

Sustained ERK signaling couples the injury response to organizer formation during Hydra head regeneration

Regenerative abilities vary widely across animals, even among closely related species, and a central challenge is to compare their gene regulatory networks (GRNs) to determine which components and regulatory connections are conserved or divergent. Hydra provides a powerful system for this work: as a cnidarian, which is the sister group to bilaterians, it offers access to deeply conserved regenerative mechanisms, and species within the genus differ in regenerative phenotypes. Here, we investigate the function of extracellular signal-regulated kinase (ERK) signaling in driving head regeneration in Hydra. ERK is a conserved injury-responsive pathway implicated in regeneration across animals, including in the activation of Wnt signaling, which is necessary and sufficient to establish the Hydra head organizer, a Wnt signaling center that patterns the main body axis. We found that in Hydra vulgaris, ERK activity extends from the generic injury phase into the period when the Wnt-based head organizer forms. However, unlike in some other regenerating species, transient ERK inhibition delayed but did not block regeneration, consistent with Hydras ability to regenerate without a proliferation-dependent blastema. ERK inhibition in H. vulgaris disrupted the transcriptional activation of multiple Wnt pathway components and restricted their expression domains, providing a likely explanation for the delayed onset of head organizer formation. Comparative experiments in Hydra oligactis, which regenerates its head approximately 24 hours more slowly than H. vulgaris, revealed reduced persistence of ERK signaling and lower sensitivity to ERK inhibition. These features suggest that while injury-induced ERK activity is conserved, the mechanisms that establish the Wnt signaling center during regeneration diverge between the two species. Together, our findings identify sustained ERK activity as a critical regulator of Wnt pathway activation during Hydra head regeneration and indicate that evolutionary shifts in the ERK-Wnt regulatory architecture contribute to species-specific differences in regenerative phenotypes.

developmental biology↗

bioRxiv2024

Molecular profile, source and lineage restriction of stem cells in an annelid regeneration model

Regeneration of missing body parts can be observed in diverse animal phyla, but it remains unclear to which extent these capacities rely on shared or divergent principles. Research into this question requires detailed knowledge about the involved molecular and cellular principles in suitable reference models. By combining single-cell RNA sequencing and mosaic transgenesis in the marine annelid Platynereis dumerilii, we map cellular profiles and lineage restrictions during posterior regeneration. Our data reveal cell-type specific injury responses, re-expression of positional identity factors, and the re-emergence of stem cell signatures in multiple cell populations. Epidermis and mesodermal coelomic tissue produce distinct putative posterior stem cells (PSCs) in the emerging blastema. A novel mosaic transgenesis strategy reveals both developmental compartments and lineage restrictions during regenerative growth. Our work supports the notion that posterior regeneration involves dedifferentiation, and reveals molecular and mechanistic parallels between annelid and vertebrate regeneration.

developmental biology↗

bioRxiv2022

A fast and versatile method for simultaneous HCR, immunohistochemistry and EdU labeling (SHInE)

Access to newer, fast and cheap sequencing techniques, particularly on the single-cell level, have made transcriptomic data of tissues or single cells accessible to many researchers. As a consequence, there is increased need for in situ visualization of gene expression or encoded proteins to validate, localize or help interpret such sequencing data, as well as put them in context with cellular proliferation. A particular challenge for labeling and imaging transcripts are complex tissues that are often opaque and/or pigmented, preventing easy visual inspection. Here we introduce a versatile protocol that combines in situ hybridization chain reaction (HCR), immunohistochemistry (IHC) and proliferative cell labeling using 5-ethynyl-2-deoxyuridine (EdU), and demonstrate its compatibility with tissue clearing. As a proof-of-concept, we show that our protocol allows for the parallel analysis of cell proliferation, gene expression and protein localization in bristleworm heads and trunks.

developmental biology↗

bioRxiv2022

Molecular characteristics of diel rhythmic diversity reveal disconnection between different levels of organismal rhythmicity

The circadian clock controls behavior and metabolism in various organisms. However, the exact timing and strength of rhythmic phenotypes can vary significantly between individuals of the same species. This is highly relevant for the rhythmically complex marine environments where organismal rhythmic diversity likely permits the occupation of different microenvironments. When investigating circadian locomotor behavior of Platynereis dumerilii, a model system for marine molecular chronobiology, we found strain-specific, high variability between individual worms. The individual patterns were reproducibly maintained for several weeks independent of basic culture conditions, such as population density or feeding. A diel head transcriptome comparison of behaviorally rhythmic versus arrhythmic wildtype worms showed that 24h cycling of core circadian clock transcripts is identical between both behavioral phenotypes. While behaviorally arrhythmic worms showed a similar total number of cycling transcripts compared to their behaviorally rhythmic counterparts, the annotation categories of their transcripts, however, differed substantially. Consistent with their locomotor phenotype, behaviorally rhythmic worms exhibit an enrichment of cycling transcripts related to neuronal/behavioral processes. In contrast, behaviorally arrhythmic worms showed significantly increased diel cycling for metabolism- and physiology-related transcripts. Phenotype-specific cycling of distinct matrix metalloproteinase transcripts, encoding extracellular enzymes that modulate synaptic circuit function and neuropeptide signaling, like pigment dispersing factor (PDF), prompted us to functionally investigate Platynereis pdf. Differing from its role in Drosophila, loss of pdf impacts on overall activity levels, but shows only indirect effects on rhythmicity. Our results show that individuals arrhythmic in a given process can show increased rhythmicity in others. Across the Platynereis population, variations of this exist as a reproducible continuum. We hypothesize that such diel rhythm breadth is an important biodiversity resource enabling the species to quickly adapt to heterogeneous marine environments and potentially also to the effects of climate change, which is however endangered with shrinking population sizes and hence diversity.

animal behavior and cognition↗

bioRxiv2019

A scalable culturing system for the marine annelid Platynereis dumerilii.

Platynereis dumerilii is a marine segmented worm (annelid) with externally fertilized embryos and it can be cultured for the full life cycle in the laboratory. The accessibility of embryos and larvae combined with the breadth of the established molecular and functional techniques has made P. dumerilii an attractive model for studying development, cell lineages, cell type evolution, reproduction, regeneration, the nervous system, and behavior. Traditionally, these worms have been kept in rooms dedicated for their culture. This allows for the regulation of temperature and light cycles, which is critical to synchronizing sexual maturation. However, regulating the conditions of a whole room present limitations, especially if experiments require being able to change culturing conditions. Here we present scalable and flexible culture methods that provide ability to control the environmental conditions, and have a multi-purpose culture space. We provide a closed setup shelving design with proper light conditions necessary for P. dumerilii to mature. We also implemented a standardized method of feeding P. dumerilii cultures with powdered spirulina which relieves the ambiguity associated with using frozen spinach, and helps standardize nutrition conditions across experiments and across different labs. By using these methods, we were able to raise mature P. dumerilii, capable of spawning and producing viable embryos for experimentation and replenishing culture populations. These methods will allow for the further accessibility of P. dumerilii as a model system, and they can be adapted for other aquatic organisms.

developmental biology↗