High impact information on ascl1a

• During normal development, ascl1a is expressed in the adenohypophysis and the adjacent diencephalon, the source of Fgf3 signals [1].
• Here, in identifying the molecular nature of the pia mutation, we investigate the role of the zebrafish achaete-scute homologue ascl1a during development of the adenohypophysis, an endocrine derivative of the placodal ectoderm [1].
• The proneural gene ascl1a is required for endocrine differentiation and cell survival in the zebrafish adenohypophysis [1].
• Two achaete-scute homolog sequences, Zash-1a and Zash-1b, were isolated from a zebrafish embryonic cDNA library [2].
• At 24 hr, the Zash-1a transcripts are found in the hindbrain in two bilaterally symmetrical lines of cells which mark the boundary between the alar and basal plates and in rhombomere 1 in ventral cells near the floorplate [2].

Biological context of ascl1a

• Furthermore, there is perfect correlation with previously established proneural gene expression patterns (i.e., absence of Mash1/Zash1a gene expression in GABA-cell-free forebrain regions) between mouse and zebrafish [3].

Anatomical context of ascl1a

• We report here that the four regions previously identified as subpallium, preoptic region, ventral thalamus and hypothalamus (i.e. ventral inferior lobe) in the postembryonic zebrafish brain show Zash-1a expression at 3 days postfertilization (dpf), whereas none of those areas express the bHLH gene neuroD (nrd) between 2 and 5 dpf [4].
• Zash-1a and -1b gene probes will be extremely useful in the analysis of additional mutations affecting development of the central nervous system in zebrafish embryos [2].
• The gene is also expressed at sites distinct from cells expressing Zash-1a in the tegmentum, diencephalon, telencephalon, and spinal cord [2].

Other interactions of ascl1a

• In the mutant cyclops, Zash-1a transcripts are absent from the ventral region of the tegmentum and in the ventral cells of rhombomere 1, while more dorsal expression regions are unaffected [2].

References