High impact information on hoxa2b

• Here we study moz mutant zebrafish in which hoxa2b and hoxb2a expression is lost and the support skeleton of the second pharyngeal segment is transformed into a duplicate of the first-segment-derived jaw skeleton [1].
• In the cranial neural crest, gene expression in the mandibular arch is unaffected in low mutants, in contrast to the hyoid arch, which shows severe reductions in dlx2 and hoxa2 expression [2].
• Overall, our results suggest that differences in the Hox PG2 gene complement of striped bass and zebrafish affects both their rhombomeric and pharyngeal arch expression patterns and may account for the similarities in pharyngeal arch expression between striped bass hoxa2a and zebrafish hoxa2b [3].
• Comparison of the striped bass HoxA cluster paralog group 2 (PG2) genes to their orthologs and trans-orthologs shows that the striped bass hoxa2a gene expression pattern is similar to the overall expression pattern described for the hoxa2 genes in the lobe-finned fish lineage and for the hoxa2b gene from zebrafish [3].
• While both hoxa2a and hoxa2b share the r1/r2 anterior boundary of expression characteristic of the hoxa2 paralog genes of other species, hoxa2a gene expression extends throughout the hindbrain, whereas hoxa2b gene expression is restricted to the r2-r5 region [3].

Biological context of hoxa2b

• Differential expression of hoxa2a and hoxa2b genes during striped bass embryonic development [3].
• Further, hoxa2b expression within the arches becomes undetectable at 60hpf, while hoxa2a expression is maintained at least up until the beginning of chondrogenesis [3].

Anatomical context of hoxa2b

• Within the pharyngeal arches, hoxa2a is expressed at higher levels in the second pharyngeal arch, while hoxa2b is more strongly expressed in the posterior arches [3].

References