Atonal homologue 8 (atoh8) is a basic helix-loop-helix transcription factor expressed in a variety of embryonic tissues. While several studies have implicated atoh8 in various developmental pathways in other species, its role in zebrafish development remains uncertain. So far, no studies have dealt with an in-depth in situ analysis of the tissue distribution of atoh8 in embryonic zebrafish. We set out to pinpoint the exact location of atoh8 expression in a detailed spatio-temporal analysis in zebrafish during the first 24 h of development (hpf). To our surprise, we observed transcription from pre-segmentation stages in the paraxial mesoderm and during the segmentation stages in the somitic sclerotome and not—as previously reported—in the myotome. With progressing maturation of the somites, the restriction of atoh8 to the sclerotomal compartment became evident. Double in situ hybridisation with atoh8 and myoD revealed that both genes are expressed in the somites at coinciding developmental stages; however, their domains do not spatially overlap. A second domain of atoh8 expression emerged in the embryonic brain in the developing cerebellum and hindbrain. Here, we observed a specific expression pattern which was again in contrast to the previously published suggestion of atoh8 transcription in neural crest cells. Our findings point towards a possible role of atoh8 in sclerotome, cerebellum and hindbrain development. More importantly, the results of this expression analysis provide new insights into early sclerotome development in zebrafish—a field of research in developmental biology which has not received much attention so far.

无调同源物 8 ( atoh8 ) 是一种在多种胚胎组织中表达的基本螺旋-环-螺旋转录因子。虽然有几项研究表明atoh8参与了其他物种的各种发育途径，但它在斑马鱼发育中的作用仍不确定。到目前为止，还没有研究对胚胎斑马鱼中atoh8的组织分布进行深入的原位分析。我们着手查明atoh8的确切位置在发育的前 24 小时 (hpf) 在斑马鱼的详细时空分析中表达。令我们惊讶的是，我们观察到了近轴中胚层的预分割阶段和体节核切片中的分割阶段的转录，而不是之前报道的肌节中的转录。随着体节的逐渐成熟，atoh8对巩膜节室的限制变得明显。与atoh8和myoD的双原位杂交表明，这两个基因在发育阶段的体细胞中都有表达。但是，它们的域在空间上并不重叠。atoh8的第二个域表达出现在发育中的小脑和后脑的胚胎脑中。在这里，我们观察到一种特定的表达模式，这再次与先前发表的神经嵴细胞中atoh8转录的建议相反。我们的研究结果表明atoh8在巩膜切开、小脑和后脑发育中可能发挥作用。更重要的是，这种表达分析的结果为斑马鱼的早期核骨发育提供了新的见解——这是迄今为止尚未受到太多关注的发育生物学研究领域。