Murakami Ryutaro, Shigenaga Ayako, Kawakita Morikazu, Takimoto Koichi, Yamaoka Ikuo, Akasaka Koji, Shimada Hiraku
Biological Institute, Faculty of Science, Yamaguchi University, 753, Yamaguchi, Japan.
Biological Laboratory, Kyushu University, 810, Ropponmatsu, Fukuoka, Japan.
Rouxs Arch Dev Biol. 1995 Sep;205(1-2):89-96. doi: 10.1007/BF00188847.
The proctodeum of the Drosophila embryo originates from the posterior end of the blastoderm and forms the hindgut. By enhancer-trap mutagenesis, using a P-element-lacZ vector, we identified a mutation that caused degeneration of the proctodeum during shortening of the germ band and named it aproctous (apro). Expression of the lacZ reporter gene, which was assumed to represent expression of the apro gene, began at the cellular blastoderm stage in a ring that encompassed about 10-15% of the egg's length (EL) and included the future proctodeum, anal pads, and posterior-most part of the visceral mesoderm. In later stages, strong expression of lacZ was detected in the developing hindgut and anal pads. Expression continued in the anal pads and epithelium of the hindgut of larvae; the epithelium of the hindgut of the adult fly also expressed lacZ. The spatial patterns of the expression of lacZ in various mutants suggested that the embryonic expression of apro was regulated predominantly by two gap genes, tailless (tll) and huckebein (hkb): tll is necessary for the activation of apro, while hkb suppressed the expression of apro in the region posterior to 10% EL. Cloning and sequencing of the apro cDNA revealed that apro was identical to the T-related gene (Trg) that is a Drosophila homolog of the vertebrate Brachyury gene. apro appears to play a key role in the development of tissues derived from the proctodeum.
果蝇胚胎的原肛起源于胚盘后端，形成后肠。通过增强子捕获诱变，利用P-元件-乳糖操纵子载体，我们鉴定出一种突变，该突变导致原肛在胚带缩短过程中退化，并将其命名为无肛（apro）。乳糖操纵子报告基因的表达，被认为代表apro基因的表达，在细胞胚盘阶段开始于一个环绕约10-15%卵长（EL）的环中，包括未来的原肛、肛垫和内脏中胚层的最后部分。在后期阶段，在发育中的后肠和肛垫中检测到乳糖操纵子的强表达。在幼虫的肛垫和后肠上皮中表达持续；成年果蝇后肠的上皮也表达乳糖操纵子。乳糖操纵子在各种突变体中的表达空间模式表明，apro的胚胎表达主要受两个间隙基因，无尾（tll）和驼背（hkb）调控：tll对apro的激活是必需的，而hkb抑制apro在EL的10%之后区域的表达。apro cDNA的克隆和测序表明，apro与T相关基因（Trg）相同，Trg是脊椎动物短尾基因在果蝇中的同源物。apro似乎在源自原肛的组织发育中起关键作用。
