Posterior Hox gene reduction in an arthropod: Ultrabithorax and Abdominal-B are expressed in a single segment in the mite Archegozetes longisetosus.
Posterior Hox gene reduction in an arthropod: Ultrabithorax and Abdominal-B are expressed in a single segment in the mite Archegozetes longisetosus.
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DOI：
10.1186/2041-9139-4-23
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发表时间：
2013-08-30
期刊：
影响因子：
4.1
通讯作者：
Thomas RH
中科院分区：
文献类型：
--
作者：
Barnett AA;Thomas RH
Hox基因编码的转录因子在所有双侧动物中具有祖先的作用，在指定沿前后轴的区域。在节肢动物（昆虫、甲壳类动物、多足类动物和螯足类动物）中，Hox基因起着指定节段身份的作用，不同节段中Hox基因表达域的变化导致了节肢动物新形态的进化。尽管如此，Hox基因在节肢动物中继发性丧失或减少其节段组成的作用相对未被探索。最近的数据表明，螨的后体标记的节段成分减少，在胚胎发育过程中只有两个节段形成图案。这与许多已灭绝和现存的螯足动物（即马蹄蟹、蝎子、蜘蛛和收割者）的观察结果相反，它们的胆体由十个或更多节组成。为了探究Hox基因在这一缩小的身体区域中的作用，我们追踪了Hox后向模式基因Ultrabithorax （Ubx）和Abdominal-B （Abd-B）以及片段极性基因patched （ptc）和engrailed （en）在长尾鳞螨（Archegozetes longisetosus）中的表达。我们发现ptc的表达模式与先前报道的减少的螨体一致。与ptc和en的表达模式相比，我们发现Ubx和Abd-B在a . longisetosus的第二个opisthosomal segment中表达在一个片段中。与Ubx相比，Abd-B最初的表达位置更靠后，即进入未分割的片段；然而，该结构域在随后的阶段被清除，并保留在第二扁桃体段。我们的研究结果表明，Ubx和Abd-B在胸腺的一个片段中表达。这是一个新的观察，因为这些基因在所有被研究的节肢动物中都在几个片段中表达。这些数据表明，压缩体分割的减少可能与压缩体中Hox基因输入的显著减少有关。
Hox genes encode transcription factors that have an ancestral role in all bilaterian animals in specifying regions along the antero-posterior axis. In arthropods (insects, crustaceans, myriapods and chelicerates), Hox genes function to specify segmental identity, and changes in Hox gene expression domains in different segments have been causal to the evolution of novel arthropod morphologies. Despite this, the roles of Hox genes in arthropods that have secondarily lost or reduced their segmental composition have been relatively unexplored. Recent data suggest that acariform mites have a reduced segmental component of their posterior body tagma, the opisthosoma, in that only two segments are patterned during embryogenesis. This is in contrast to the observation that in many extinct and extant chelicerates (that is, horseshoe crabs, scorpions, spiders and harvestmen) the opisthosoma is comprised of ten or more segments. To explore the role of Hox genes in this reduced body region, we followed the expression of the posterior-patterning Hox genes Ultrabithorax (Ubx) and Abdominal-B (Abd-B), as well as the segment polarity genes patched (ptc) and engrailed (en), in the oribatid mite Archegozetes longisetosus. We find that the expression patterns of ptc are in agreement with previous reports of a reduced mite opisthosoma. In comparison to the ptc and en expression patterns, we find that Ubx and Abd-B are expressed in a single segment in A. longisetosus, the second opisthosomal segment. Abd-B is initially expressed more posteriorly than Ubx, that is, into the unsegmented telson; however, this domain clears in subsequent stages where it remains in the second opisthosomal segment. Our findings suggest that Ubx and Abd-B are expressed in a single segment in the opisthosoma. This is a novel observation, in that these genes are expressed in several segments in all studied arthropods. These data imply that a reduction in opisthosomal segmentation may be tied to a dramatically reduced Hox gene input in the opisthosoma.
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影响因子：
0.8
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