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Welch, M. J.

Publications and source records attributed to Welch, M. J..

3 recordsLinked to original sources

Cross-talk between tissues is critical for intergenerational acclimation to environmental change

An organisms reaction to environmental changes is mediated by coordinated responses of multiple tissues. Additionally, parental priming may increase offsprings acclimation potential to changing environmental conditions. As the effects of human-induced climate change, such as ocean acidification (OA), continue to intensify it is critical to assess the acclimation potential of species at the whole organismal scale. For this we need to understand the cross-talk between tissues in regulating and responding to pH changes. Here by using a multi-tissue approach we determine the influence of 1) variation in parental behavioural tolerance and 2) parental environment, on molecular responses of their offspring in a coral reef fish. The gills and liver showed the highest transcriptional response to OA conditions in juvenile fish regardless of the parental environment, while the brain and liver showed the greatest signal of intergenerational acclimation. Key functional pathways that were altered in the brain upon within-generational CO2 exposure were restored to control levels when parents were exposed to OA conditions. Furthermore, the expression of a new complement of genes involved in key functions was altered in the offspring only when parents were previously exposed to OA conditions. Therefore, previous parental conditioning to OA can reprogram tissue transcriptomic profiles of the offspring enabling them to better cope in an environment with elevated CO2 levels. Overall, our results reveal tissue-specific transcriptional changes underlying intergenerational plastic responses to elevated CO2 exposure and highlight the integration of these changes in promoting organismal acclimation to OA.

ecology↗

Genetic architecture of behavioural resilience to ocean acidification

Genetic variation is essential for adaptation to rapid environmental changes. Identifying genetic variation associated with climate-change related phenotypes is therefore the necessary first step towards predictive models of genomic vulnerability. Here we used a whole-genome scan to identify candidate genetic variants associated with differences in behavioural resilience to ocean acidification in a coral reef fish. We identified three genomic regions that differ between individuals that are behaviourally tolerant compared with behaviourally sensitive to elevated CO2. These include a dopamine receptor (drd4rs), cadherin related family member 5-like (cdhr5l), Synapse-associated protein 1 (syap1), and GRB2 Associated Regulator of MAPK1 Subtype 2 (garem2), which have previously been found to modify behaviour related to boldness, novelty seeking, and learning in other species, and differ between behaviourally tolerant and sensitive individuals. Consequently, the identified genes are promising candidates in the search of the genetic underpinnings and adaptive potential of behavioural resilience to ocean acidification in fishes.

ecology↗

Human pluripotent stem cell-derived photoreceptors switch from cell autonomous axon extension to non-cell autonomous process pulling during synaptic marker redistribution.

Photoreceptors (PRs) are the primary visual sensory cells, and their loss leads to blindness that is currently incurable. Cell replacement therapy holds promise as a therapeutic approach to restore vision to those who have lost PRs through damage or disease. While PR transplant research is ongoing in animal models, success is hindered by our limited understanding of PR axon growth during development and regeneration. Using a human pluripotent stem cell (hPSC) reporter line that labels PRs (WA09 CRX+/tdTomato), we generated retinal organoids in order to study mechanisms of PR process extension. We found that the earliest born PRs exhibit autonomous axon extension from dynamic terminals that appear similar to projection neuron growth cones. However, as hPSC-derived PRs age from 40 to 80 days of differentiation, they lose dynamic terminals in 2D plated cultures and within 3D retinal organoids, which does not correlate with cell birth date. Using a rod-specific hPSC reporter line (WA09 NRL+/eGFP), we further determined that rod PRs never form motile growth cones. Interestingly, PRs without motile terminals are still capable of extending axons, but neurites are generated from process stretching via their attachment to motile non-PR cells, which underlies the observed differences in PR neurite lengths on different substrata. While immobile PR terminals express actin, it is less polymerized and less organized than actin present in motile terminals. However, immobile PRs do localize synaptic proteins to their terminals, suggesting a normal developmental progression. These findings help inform the development of PR transplant therapies to treat blinding diseases and provide a platform to test treatments that restore autonomous PR axon extension. Significance StatementLoss of photoreceptors (PRs) in the retina through damage or disease causes irreversible vision loss and blindness. One treatment approach is to replace lost cells with transplanted human stem cell-derived PRs, but this requires PR axons to integrate into the host retina to restore the required neural connections. For this strategy to succeed, we need to understand how PRs extend processes to their targets during development in situ, and whether dissociated human stem cell (hPSC)-derived PRs behave in a similar fashion. In this paper, we show that hPSC-PRs have only a short window during which they are capable of autonomous axon extension, which has implications for PR transplant efforts and for our basic understanding of human retinal development.

neuroscience↗