Segmentation and specification of the Drosophila mesoderm
Segmentation and specification of the Drosophila mesoderm
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DOI：
10.1101/gad.10.24.3183
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发表时间：
1996-12-15
影响因子：
10.5
通讯作者：
Frasch, M
中科院分区：
文献类型：
--
作者：
Azpiazu, N;Lawrence, PA;Frasch, M
发育中的中胚层的图案化在每个节中的确定的前后和背腹位置建立内脏、躯体和心脏组织的原基。在这里，我们研究的机制，定位和确定这些原基。我们专注于两个中胚层基因的调控：风笛（bap），它定义了中肠内脏肌肉组织的原基，和蛇（srp），它标志着脂肪体的原基。这两个基因在每个副片段前部的中胚层细胞的特定群体中被激活。其他基因标志着心脏和体细胞中胚层的原基，这些基因主要在来自每个parsegment后部的细胞中表达。因此，副片段似乎被细分了，至少就这些基因而言，这种细分取决于配对规则基因，如偶跳基因（eve）。我们用遗传镶嵌显示夏娃在中胚层中自主活动。我们还表明，刺猬（HH）和无翅（WG）介导的中胚层的配对规则基因的功能，可能部分通过中胚层内的作用，部分通过外胚层的诱导信号。HH是每个旁节前部中BAP和SIP的正常激活所必需的，而WG是抑制后部中BAP和SRP表达所必需的。因此，hh和wg在中胚层分裂中起着相反的作用。
Patterning of the developing mesoderm establishes primordia of the visceral, somatic, and cardiac tissues at defined anteroposterior and dorsoventral positions in each segment. Here we examine the mechanisms that locate and determine these primordia. We focus on the regulation of two mesodermal genes: bagpipe (bap), which defines the anlagen of the visceral musculature of the midgut, and serpent (srp), which marks the anlagen of the fat body. These two genes are activated in specific groups of mesodermal cells in the anterior portions of each parasegment. Other genes mark the anlagen of the cardiac and somatic mesoderm and these are expressed mainly in cells derived from posterior portions of each parasegment. Thus the parasegments appear to be subdivided, at least with respect to these genes, a subdivision that depends on pair-rule genes such as even-skipped (eve). We show with genetic mosaics that eve acts autonomously within the mesoderm. We also show that hedgehog (hh) and wingless (wg) mediate pair-rule gene functions in the mesoderm, probably partly by acting within the mesoderm and partly by inductive signaling from the ectoderm. hh is required for the normal activation of bap and sip in anterior portions: of each parasegment, whereas wg is required to suppress bap and srp expression in posterior portions. Hence, hh and wg play opposing roles in mesoderm segmentation.