An exclusively mesodermal origin of fin mesenchyme demonstrates that zebrafish trunk neural crest does not generate ectomesenchyme

Abstract

SUMMARYThe neural crest is a multipotent stem cell population that arises from the dorsal aspect of the neural tube and generates both nonectomesenchymal (melanocytes, peripheral neurons and glia) and ectomesenchymal (skeletogenic, odontogenic, cartilaginous and connective tissue) derivatives. In amniotes, only cranial neural crest generates both classes, with trunk neural crest restricted to nonectomesenchyme. By contrast, it has been suggested that anamniotes might generate derivatives of both classes at all axial levels, with trunk neural crest generating fin osteoblasts, scale mineral-forming cells and connective tissue cells; however, this has not been fully tested. The cause and evolutionary significance of this cranial/trunk dichotomy, and its absence in anamniotes, are debated. Recent experiments have disputed the contribution of fish trunk neural crest to fin osteoblasts and scale mineral-forming cells. This prompted us to test the contribution of anamniote trunk neural crest to fin connective tissue cells. Using genetics-based lineage tracing in zebrafish, we find that these fin mesenchyme cells derive entirely from the mesoderm and that neural crest makes no contribution. Furthermore, contrary to previous suggestions, larval fin mesenchyme cells do not generate the skeletogenic cells of the adult fin, but persist to form fibroblasts associated with adult fin rays. Our data demonstrate that zebrafish trunk neural crest does not generate ectomesenchymal derivatives and challenge long-held ideas about trunk neural crest fate. These findings have important implications for the ontogeny and evolution of the neural crest.

The zebrafish tailbud contains two independent populations of midline progenitor cells that maintain long-term germ layer plasticity and differentiate based on local signaling cues

“…Prior work demonstrated that the PWPCs have germ layer plasticity and give rise to the somites, vasculature and spinal cord (Martin and Kimelman, 2012;Takemoto et al, 2011;Tzouanacou et al, 2009). It can also be assumed that in zebrafish the fin mesenchyme, which originates solely from presomitic mesoderm, is derived from PWPCs of the tailbud, as this is the major source of posterior paraxial mesoderm (Lee et al, 2013). Here we show that the remainder of the posterior body is derived from two populations of germ layer plastic MPCs.…”

Ribozyme Mediated gRNA Generation for In Vitro and In Vivo CRISPR/Cas9 Mutagenesis

“…Whole mount immunohistochemistry was performed as previously described [17]. Primary antibodies were: chicken anti-GFP (1:500; ab13970, Abcam), rabbit anti-DsRed/mCherry (1:500; 632496, BD Biosciences), and mouse anti-engrailed (1:50, 4D9, DSHB).…”

Clarification of mural cell coverage of vascular endothelial cells by live imaging of zebrafish

“…S7G,H). Because activity of the tbx6 promoter used to express Cre recombinase is relatively low in the dorsal mesoderm, we also utilized the no tail a (ntla; ta -Zebrafish Information Network) promoter, which is active in the dorsal mesoderm (Goering et al, 2003;Lee et al, 2013). In pdgfrb reporter larvae injected with a plasmid (ntla:Cre-2A-mCherry), mVenus-positive MCs were detected not only in the trunk vessels but also in the hindbrain vessels (Fig.…”