Altered distributions of Ultrabithorax transcripts in extra sex combs mutant embryos of Drosophila.
Altered distributions of Ultrabithorax transcripts in extra sex combs mutant embryos of Drosophila.
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DOI：
10.1002/j.1460-2075.1985.tb04075.x
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发表时间：
1985-12
期刊：
影响因子：
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通讯作者：
G. Struhl;M. Akam
中科院分区：
文献类型：
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作者：
G. Struhl;M. Akam
胚胎发生早期需要额外性梳（esc）基因的产物，以确保在随后的发育过程中双胸和触角基因复合物的正确空间表达。在这里，我们描述了突变ESC胚胎中Ultrabithorax (Ubx)基因转录的空间和时间模式。在野生型胚胎中，Ubx转录本首先在特定胸段和腹段的胚盘原基中检测到，主要是在构成副段6的祖细胞的细胞带中：原肠胚形成后，高水平的转录物在包括副段6-12的胚带的严格限制区域中积累。在 ESC 胚胎中，Ubx 转录本的初始模式似乎与野生型胚胎没有区别。然而，在原肠胚形成和胚带延伸之后，Ubx 转录物在身体的大多数外胚层和中胚层衍生物中积累，包括所有 14 个副节段的转录物。然后，转录本的丰度下降，因此在胚带缩短后（受精后 12 小时），每个副片段中仅检测到低水平。这些结果表明，esc基因产物不参与选择Ubx基因表达的位置，而是随后起作用以确保该基因在其最初未被激活的那些原基中保持关闭状态。此外，他们还提出其他同源基因可能调节 Ubx 表达的可能性——在这种情况下，其他不加区别表达的同源基因的累积产物可下调全身的 Ubx 转录。
The product of the extra sex combs (esc) gene is required early in embryogenesis to ensure the correct spatial expression of the bithorax and Antennapedia gene complexes during subsequent development. Here we describe the spatial and temporal patterns of transcription of the Ultrabithorax (Ubx) gene in mutant esc embryos. In wild‐type embryos, Ubx transcripts are first detected in the blastoderm primorida of particular thoracic and abdominal segments, predominately in a band of cells constituting the progenitor cells of parasegment 6: after gastrulation, high levels of transcript accumulate in a sharply restricted region of the germ band comprising parasegments 6‐12. In esc‐ embryos, the initial pattern of Ubx transcripts appears indistinguishable from that of wild‐type embryos. However, following gastrulation and germ band extension, Ubx transcripts accumulate in most of the ectodermal and mesodermal derivatives of the body, including those of all 14 parasegments. Then, the abundance of the transcripts declines so that after germ band shortening (12 h after fertilization), only low levels are detected in each parasegment. These results show that the esc gene product is not involved in choosing where the Ubx gene is to be expressed, but rather, that it acts subsequently to ensure that the gene remains off in those primordia in which it is not initially activated. In addition, they suggest the possibility that other homeotic genes may regulate Ubx expression ‐‐in this case, the accumulating products of other indiscriminately expressed homeotic genes serving to down‐regulate Ubx transcription throughout the body.