Gene expression patterns underlying proximal–distal skeletal segmentation in late‐stage zebrafish,Danio rerio

Abstract

Timing and pattern of expression of ten candidate segmentation genes or gene pairs were reviewed or examined in developing median fins of late-stage zebrafish, Danio rerio. We found a general correspondence in timing and pattern of expression between zebrafish fin radial segmentation and tetrapod joint development, suggesting that molecular mechanisms underlying radial segmentation have been conserved over 400 million years of evolution. Gene co-expression during segmentation (5.5-6.5 mm SL) is similar between tetrapods and zebrafish: bmp2b, bmp4, chordin, and gdf5 in interradial mesenchyme and ZS; bapx1, col2a1, noggin3, and sox9a in chondrocytes. Surprisingly, wnt9a is not expressed in the developing median fins, though wnt9b is detected. In contrast to all other candidate segmentation genes we examined, bapx1 is not expressed in the caudal fin, which does not segment. Together, these data suggest a scenario of gene interactions underlying radial segmentation based on the patterns and timing of candidate gene expression. Developmental Dynamics 236:3111-3128, 2007.

Development of the viscerocranial skeleton during embryogenesis of the sea lamprey,Petromyzon Marinus

“…However, our results and those reported elsewhere suggest dorsoventral differences in the branchial cartilage elements may be present in this basal vertebrate and the ability to separate these skeletal elements developmentally might have been a key factor in the evolution of branchial articulation, and cartilage segmentation within vertebrates (Crotwell and Mabee, 2007). A recent study suggests that developmental mechanisms patterning the branchial arches and paired fin skeletons are shared in vertebrates (Gillis et al, 2009).…”

Evx1 is required for joint formation in zebrafish fin dermoskeleton

“…As mentioned in the introduction, the separation of proximal and distal radials in the anal and dorsal fin endoskeleton is thought to be homologous to joint formation in tetrapod limbs (Crotwell and Mabee, 2007). However, before this analysis, it was unclear whether dermoskeletal joint formation also uses the same genetic mechanisms.…”

“…Most notably, the former progress through a cartilaginous stage whereas the latter do not (Geraudie and Landis, 1982;Landis and Geraudie, 1990;Smith, 1994;Hinchliffe, 2002;Suzuki et al, 2003;Mari-Beffa et al, 2007). The separation of proximal and distal radials in the endoskeleton of these fins is thought to be homologous to joint formation in amniote limbs (where the bones also progress through a cartilaginous stage) and similar factors are expressed during both of these processes (Crotwell et al, 2001;Crotwell and Mabee, 2007). However, before our analysis of the evx1 mutant, it was not clear whether this genetic homology also extended to the lepidotrichia joints.…”

Zebrafish development and regeneration: new tools for biomedical research

“…To date, zebrafish and medaka have not been fully appreciated as systems which can make a real contribution to the field of osteogenesis and osteoblast function. None the less, genes important in mammalian osteogenesis and skeletal patterning have zebrafish orthologues whose expression patterns suggest functional conservation (Crotwell and Mabee, 2007;Mari-Beffa et al, 2007).…”

“…To date, zebrafish and medaka have not been fully appreciated as systems which can make a real contribution to the field of osteogenesis and osteoblast function. None the less, genes important in mammalian osteogenesis and skeletal patterning have zebrafish orthologues whose expression patterns suggest functional conservation (Crotwell and Mabee, 2007;Mari-Beffa et al, 2007).Using histological staining as a read-out for bone formation, a genome-wide, large scale forward genetic screen has been carried out in zebrafish. This led to the identification of 101 mutants with defects in bone formation (Fig.…”