Uppsala University, Department of Earth Sciences, Palaeobiology, Uppsala, Sweden.
Dev Biol. 2011 Sep 1;357(1):64-72. doi: 10.1016/j.ydbio.2011.05.670. Epub 2011 Jun 1.
Segmentation, i.e. the subdivision of the body into serially homologous units, is one of the hallmarks of the arthropods. Arthropod segmentation is best understood in the fly Drosophila melanogaster. But different from the situation in most arthropods in this species all segments are formed from the early blastoderm (so called long-germ developmental mode). In most other arthropods only the anterior segments are formed in a similar way (so called short-germ developmental mode). Posterior segments are added one at a time or in pairs of two from a posterior segment addition zone. The segmentation mechanisms are not universally conserved among arthropods and only little is known about the genetic patterning of the anterior segments. Here we present the expression patterns of the insect head patterning gene orthologs hunchback (hb), orthodenticle (otd), buttonhead-like (btdl), collier (col), cap-n-collar (cnc) and crocodile (croc), and the trunk gap gene Krüppel (Kr) in the myriapod Glomeris marginata. Conserved expression of these genes in insects and a myriapod suggests that the anterior segmentation system may be conserved in at least these two classes of arthropods. This finding implies that the anterior patterning mechanism already existed in the last common ancestor of insects and myriapods.
分段，即将身体分为连续同源单位，是节肢动物的特征之一。在果蝇 Drosophila melanogaster 中，节肢动物的分段最容易理解。但与该物种中大多数节肢动物的情况不同，所有的节段都是由早期的囊胚（所谓的长胚发育模式）形成的。在大多数其他节肢动物中，只有前节段以类似的方式形成（所谓的短胚发育模式）。后节段一个一个地或成双成对地从前节段添加区添加。节段化机制在节肢动物中并非普遍保守，而且关于前节段的遗传模式知之甚少。在这里，我们展示了昆虫头部模式基因同源物 hunchback（hb）、orthodenticle（otd）、buttonhead-like（btdl）、collier（col）、cap-n-collar（cnc）和 crocodile（croc）以及多足类动物 Glomeris marginata 中的躯干间隙基因 Krüppel（Kr）的表达模式。这些基因在昆虫和多足类动物中的保守表达表明，前节段系统至少在这两个类节肢动物中是保守的。这一发现意味着在前节段化机制已经存在于昆虫和多足类动物的最后共同祖先中。
