Bowl is required downstream of Notch for elaboration of distal limb patterning
Bowl is required downstream of Notch for elaboration of distal limb patterning
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DOI：
10.1242/dev.00833
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发表时间：
2003-12-01
期刊：
影响因子：
4.6
通讯作者：
Bray, SJ
中科院分区：
文献类型：
--
作者：
Ibeas, JMD;Bray, SJ
在果蝇的腿中，Notch的激活导致将附肢细分为节的关节的建立。我们发现，碗突变导致类似的表型的缺口，导致融合和截断的跗节（tarsomeres），并像它的近亲奇数跳过，碗是响应于缺口信号在一个子集的部分边界。然而，尽管碗突变克隆导致融合的tarsomeres，碗蛋白只发现在t1/胫骨和t5/前跗骨边界，而不是在tarsomeres关节。调和这些数据的一个假设是碗在跗骨发育的早期阶段起作用。因此，我们研究了碗突变对腿部“间隙”基因表达的影响，这些基因赋予发育中的腿部区域身份。这些基因中的几个在碗突变细胞中改变了表达。例如，bric-a-brac 2通常在跗骨结构域的中心部分表达，但在碗克隆中扩展到远端和近端区域。相反，异位碗导致bric-a-brac 2减少，伴随着近端（t1）和远端（t5）tarsomere命运的扩张。因此，碗基因是必要的，在跗骨的图案的阐述和它的影响提出了一个渐进的模型，用于确定P/D身份。这一机制可能在节肢动物肢体的多样化中很重要，因为它解释了分节的跗节是如何从具有不分节的跗骨的祖先肢体中产生的。
In the Drosophila leg, activation of Notch leads to the establishment of the joints that subdivide the appendage into segments. We find that mutations in bowl result in similar phenotypes to Notch, causing fusion and truncations of tarsal segments (tarsomeres) and, like its close relative Odd-skipped, Bowl is produced in response to Notch signalling at a subset of segment boundaries. However, despite the fact that bowl mutant clones result in fusion of tarsomeres, Bowl protein is only found at the t1/tibial and t5/pretarsal boundaries, not at tarsomere joints. One hypothesis to reconcile these data is that bowl has a role at an earlier stage in tarsal development. We therefore investigated the effects of bowl mutations on the expression of leg 'gap' genes that confer regional identity on the developing leg. Several of these genes have altered expression in bowl mutant cells. For example, bric-a-brac2 is normally expressed in the central part of the tarsus domain but expands into distal and proximal regions in bowl clones. Conversely, ectopic bowl leads to a reduction in bric-a-brac2, with a concomitant expansion of proximal (t1) and distal (t5) tarsomere fates. The bowl gene is therefore required for the elaboration of pattern in the tarsus and its effects suggest a progressive model for the determination of P/D identities. This mechanism might be important in the diversification of arthropod limbs, because it explains how segmented tarsomeres could have arisen from an ancestral limb with an unsegmented tarsus.