dparichy.bsky.social
developmental genetics, genomics of adult traits and evolution | zebrafish, danios, guppy, wrasses, mandarin fish | neural crest, stem cells, pigment, skin | University of Virginia Biology | parichylab.org | #DevBio #EvoDevo #NeuralCrest
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For sure… did my best to make that clear!
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“Yeah what about it” was pretty much exactly what McGuire(R) VA-5 staffer had to say when contacted
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VA-5 (R) staffer: nothing to be done, government just can’t afford these costs anymore.
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As usual, a heroic job from our own folks, especially Dylan, and great fun working with our collaborators, and of course thanks to NIH and the MIRA mechanism for letting us go where the science leads.
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We believe this is all pretty cool because (i) it shows how a differentiated cell type has been “repurposed” to have an entirely new phenotype and (ii) it shows the importance of positional information even in a species best known for self-organizing its pattern.
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Putting it all together, we think this is what’s going on.
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So how do BMP (and Agouti) drive fate conversion? Transcription factors Foxd3 (well known) and Runx3 (not well known in pigment biology) are downstream of BMP and necessary and sufficient to effect melanin loss and purine gain.
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But even knocking out both Agouti genes didn’t eliminate all the white cells so we looked further and identified an additional role for BMPs, which pattern the fin more generally. Here BMPs signal through non-canonical receptors including Rgmb.
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We hypothesized that positional information specifies where transdifferentiation should happen. scRNA-seq, mutants and transgenes showed that one such cue is Agouti-related Asip1, which acts in concert with another Agouti peptide, Asip2b,
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Here’s a kickass FIB-SEM movie of a transitional cell, showing organelles in various states of degradation or development (this took a week of instrument time).
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We showed previously that white cells—melanoleucophores—differentiate from melanophores. Here we show how this occurs, with massive changes in transcriptome, turnover of pigmentary organelles, loss of melanin and gain of white guanine crystals.
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Ontogenetic, nuptial, physiological? Several possible contacts.
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Congrats! Look forward to reading this.
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