Chelicerate Hox genes and the homology of arthropod segments
Chelicerate Hox genes and the homology of arthropod segments
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DOI：
10.1046/j.1525-142x.1999.99014.x
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发表时间：
1999-09-01
影响因子：
2.9
通讯作者：
Kaufman, TC
中科院分区：
文献类型：
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作者：
Abzhanov, A;Popadic, A;Kaufman, TC
昆虫和脊椎动物的同源共生复合体(Hom-C)基因是沿着前后轴指定节段所必需的。马蹄蟹HOX基因的多个平行序列已被用来作为Hom-C在蟹类中复制的证据。我们通过有限的聚合酶链式反应调查两种蜘蛛物种的同源盒样本来解决这一可能性，这两种蜘蛛是三角硬脂蜘蛛和毛足蛛。这项调查没有提供多个HOX簇的证据，尽管我们发现了鼻足(PB)和变形(DFD)的明显重复副本。此外，我们还克隆了PB、zernuullt(Zen/Hox3)和DFD的较大的cDNA片段。这些片段可以通过原位杂交来确定mRNA的分布。我们的结果与之前发表的来自另一只蜘蛛和一只甲螨的HOX基因的表达模式相似。以前的研究比较了蜘蛛/螨类HOX基因与昆虫的表达模式，并基于HOX结构域的共线前边界可以作为标记的假设，提出了一种节段性同源性模式。为了验证这一假设，我们对海龟、多足类、甲壳类和昆虫中Ubx/Abd-A的表达模式进行了比较分析。我们的结论是，在节肢动物进化过程中，前边界可能会发生很大的变化，因此，不应将HOX表达模式作为识别不同类别节肢动物同源性的唯一标准。
Genes of the homeotic complex (HOM-C) in insects and vertebrates are required for the specification of segments along the antero-posterior axis. Multiple paralogues of the Hox genes in the horseshoe crab Limulus poliphemus have been used as evidence for HOM-C duplications in the Chelicerata. We addressed this possibility through a limited PCR survey to sample the homeoboxes of two spider species, Steatoda triangulosa and Achaearanea tepidariorum. The survey did not provide evidence for multiple Hox clusters although we have found apparent duplicate copies of proboscipedia (pb) and Deformed (Dfd). In addition, we have cloned larger cDNA fragments of pb, zerknullt (zen/Hox3) and Dfd. These fragments allowed the determination of mRNA distribution by in situ hybridization. Our results are similar to the previously published expression patterns of Hox genes from another spider and an oribatid mite. Previous studies compared spider/mite Hox gene expression patterns with those of insects and argued for a pattern of segmental homology based on the assumption that the co-linear anterior boundaries of the Hox domains can be used as markers. To test this assumption we performed a comparative analysis of the expression patterns for UBX/ABD-A in chelicerates, myriapods, crustaceans, and insects. We conclude that the anterior boundary can be and is changed considerably during arthropod evolution and, therefore, Hox expression patterns should not be used as the sole criterion for identifying homology in different classes of arthropods.