HUNCHBACK, A GENE REQUIRED FOR SEGMENTATION OF AN ANTERIOR AND POSTERIOR REGION OF THE DROSOPHILA EMBRYO
HUNCHBACK, A GENE REQUIRED FOR SEGMENTATION OF AN ANTERIOR AND POSTERIOR REGION OF THE DROSOPHILA EMBRYO
复制标题
DOI：
10.1016/0012-1606(87)90045-5
复制
发表时间：
1987-02-01
影响因子：
2.7
通讯作者：
NUSSLEINVOLHARD, C
中科院分区：
文献类型：
--
作者：
LEHMANN, R;NUSSLEINVOLHARD, C
驼背基因（hb）是果蝇的gap类分割基因中的一员。许多x射线诱发的缺失定位hb位点在染色体位置85A3-B1，在粉红色位点的右侧，在相同的间隔内绘制。共研究了14个EMS等位基因和3个x射线诱导的hb等位基因。纯合子突变胚胎在两个不同的区域显示片段的缺失。在6个强等位基因中，阴唇和3个胸椎节段在前面缺失，而腹部第8节和腹部第7节的邻近部分在后面缺失。8个弱等位基因在胸部和后腹部区域均有较小的缺失。在最弱的等位基因中，只有部分胸膜被删除。三个hb等位基因产生同质转化：叠加在强或弱缺失表型上，头或胸段分别转化为腹部段。这表明hb也可能参与Bithorax复合体（BX-C）基因的调控。利用紫外激光束消融技术（Lohs-Schardin et al., 1979）对强突变胚胎中正常出现的片段进行命运映射（Fate mapping），结果表明这些片段来自正常胚皮区域。突变表型可以在原肠胚形成后不久被识别，因为它不能完全扩展胚芽带。在6小时的突变胚胎中，在胸部和后腹部区域观察到两簇死细胞。这些观察结果表明hb基因功能的区域特异性要求。纯合突变极细胞移植对种系嵌合体的分析表明，hb在卵发生过程中已经表达。由纯合突变种系衍生的纯合突变胚具有新的表型。前受累区扩大，包括所有三个颌节和前三个腹部节。此外，在剩余的头部结构和后腹部之间形成了三个极性相反的腹部节。来自纯合突变种系的杂合突变胚胎发育正常，表明正常发育不需要母体基因表达。
The locus hunchback (hb) is a member of the gap class of segmentation genes of Drosophila. A number of X-ray-induced deletions locate the hb locus at the chromosomal site 85A3-B1, to the right of the pink locus, which maps in the same interval. A total of 14 EMS and 3 X-ray-induced hb alleles have been studied. Homozygous mutant embryos show deletions of segments in two separate regions. In the six strong alleles, the labium and all three thoracic segments are deleted anteriorly while posteriorly the 8th abdominal segment and adjacent parts of the 7th abdominal segment are lacking. The eight weak alleles show smaller deletions both in the thoracic and posterior abdominal region. In the weakest allele only part of the mesothorax is deleted. Three hb alleles produce a homoeotic transformation: superimposed on a strong or weak deletion phenotype, head or thoracic segments are transformed into abdominal segments, respectively. This suggests that hb might also be involved in the regulation of genes in the Bithorax complex (BX-C). Fate mapping of the normal-appearing segments in strong mutant embryos using the UV-laser beam ablation technique (Lohs-Schardin et al., 1979) shows that these segments arise from the normal blastoderm regions. The mutant phenotype can be recognized soon aftser the onset of gastrulation in a failure to fully extend the germ band. In 6-hr-old mutant embryos, two clusters of dead cells are observed in the thoracic and posterior abdominal region. These observations indicate region specific requirement of hb gene function. The analysis of germ line chimeras by transplantation of homozygous mutant pole cells shows that hb is already expressed during oogenesis. Homozygous mutant embryos derived from a homozygous mutant germ line have a novel phenotype. The anterior affected region is enlarged, including all three gnathal segments and the anterior three abdominal segments. In addition three abdominal segments with reversed polarity are formed between the remaining head structures and the posterior abdomen. Heterozygous mutant embryos derived from a homozygous mutant germ line develop normally, indicating that maternal gene expression is not required for normal development.