Schinko Johannes B, Kreuzer Nina, Offen Nils, Posnien Nico, Wimmer Ernst A, Bucher Gregor
Department of Developmental Biology, Johann Friedrich Blumenbach Institute of Zoology and Anthropology, Georg-August-University Göttingen, Germany.
Dev Biol. 2008 May 15;317(2):600-13. doi: 10.1016/j.ydbio.2008.03.005. Epub 2008 Mar 15.
The head gap genes orthodenticle (otd), empty spiracles (ems) and buttonhead (btd) are required for metamerization and segment specification in Drosophila. We asked whether the function of their orthologs is conserved in the red flour beetle Tribolium castaneum which in contrast to Drosophila develops its larval head in a way typical for insects. We find that depending on dsRNA injection time, two functions of Tc-orthodenticle1 (Tc-otd1) can be identified. The early regionalization function affects all segments formed during the blastoderm stage while the later head patterning function is similar to Drosophila. In contrast, both expression and function of Tc-empty spiracles (Tc-ems) are restricted to the posterior part of the ocular and the anterior part of the antennal segment and Tc-buttonhead (Tc-btd) is not required for head cuticle formation at all. We conclude that the gap gene like roles of ems and btd are not conserved while at least the head patterning function of otd appears to be similar in fly and beetle. Hence, the ancestral mode of insect head segmentation remains to be discovered. With this work, we establish Tribolium as a model system for arthropod head development that does not suffer from the Drosophila specific problems like head involution and strongly reduced head structures.
头部间隙基因正齿（otd）、空气门（ems）和纽扣头（btd）对于果蝇的体节化和体节特化是必需的。我们研究了它们在赤拟谷盗中的直系同源基因功能是否保守，赤拟谷盗与果蝇不同，其幼虫头部以昆虫典型的方式发育。我们发现，根据双链RNA注射时间，可以确定Tc-正齿1（Tc-otd1）的两种功能。早期的区域化功能影响胚盘阶段形成的所有体节，而后期的头部模式形成功能与果蝇相似。相比之下，Tc-空气门（Tc-ems）的表达和功能都局限于眼的后部和触角节的前部，而Tc-纽扣头（Tc-btd）对于头部表皮形成根本不是必需的。我们得出结论，ems和btd类似间隙基因的作用并不保守，而至少otd的头部模式形成功能在果蝇和甲虫中似乎是相似的。因此，昆虫头部节段化的原始模式仍有待发现。通过这项工作，我们建立了赤拟谷盗作为节肢动物头部发育的模型系统，该系统不存在果蝇特有的问题，如头部内卷和头部结构大幅减少。
