hunchback is required for suppression of abdominal identity, and for proper germband growth and segmentation in the intermediate germband insect Oncopeltus fasciatus
hunchback is required for suppression of abdominal identity, and for proper germband growth and segmentation in the intermediate germband insect Oncopeltus fasciatus
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DOI：
10.1242/dev.01046
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发表时间：
2004-04-01
期刊：
影响因子：
4.6
通讯作者：
Kaufman, TC
中科院分区：
文献类型：
--
作者：
Liu, PZ;Kaufman, TC
昆虫如黑腹果蝇（Drosophila melanogaster）经历一种衍生形式的分割，称为长胚带分割。在长胚带昆虫中，所有的身体区域都由胚盘阶段指定。因此，整个身体平面在胚盘上按比例呈现。这与只有最前面的身体区域由胚盘阶段指定的短和中间胚带昆虫相反。后体节在胚带伸长的胚胎发生后期被指定。虽然我们对果蝇的分节了解很多，但我们对短胚带和中间胚带昆虫的胚盘如何只分配到前段以及剩余的后段如何产生仍然知之甚少。为了深入了解这种类型的胚胎发生，我们研究了果蝇间隙基因hunchback的同源物在中间生殖昆虫，马利筋虫，Oncopeltus fasciatus的表达和功能。我们发现Oncopeltus hunchback（Of 'HB）在两个阶段中表达，首先在胚盘中的间隙样结构域中，然后在胚带伸长期间的后部生长区中。为了确定Of 'hb的遗传功能，我们已经开发了一种在乳草虫中进行亲本RNAi的方法。使用这种技术，我们发现Oncopeltus驼背有两个角色在前后轴规格。第一，Of 'hb是需要抑制腹部的身份在下颚和胸部区域。随后，需要适当的胚带生长和分割。在因驼背而耗尽的马利筋虫胚胎中，这两种效应导致动物的头部相对正常，随后是几个具有腹部特征的节段。这种表型让人想起在果蝇驼背突变体中发现的表型，但在Oncopeltus中是通过两个单独的缺陷的组合产生的。
Insects such as Drosophila melanogaster undergo a derived form of segmentation termed long germband segmentation. In long germband insects, all of the body regions are specified by the blastoderm stage. Thus, the entire body plan is proportionally represented on the blastoderm. This is in contrast to short and intermediate germband insects where only the most anterior body regions are specified by the blastoderm stage. Posterior segments are specified later in embryogenesis during a period of germband elongation. Although we know much about Drosophila segmentation, we still know very little about how the blastoderm of short and intermediate germband insects is allocated into only the anterior segments, and how the remaining posterior segments are produced. In order to gain insight into this type of embryogenesis, we have investigated the expression and function of the homolog of the Drosophila gap gene hunchback in an intermediate germ insect, the milkweed bug, Oncopeltus fasciatus. We find that Oncopeltus hunchback (Of'hb) is expressed in two phases, first in a gap-like domain in the blastoderm and later in the posterior growth zone during germband elongation. In order to determine the genetic function of Of'hb, we have developed a method of parental RNAi in the milkweed bug. Using this technique, we find that Oncopeltus hunchback has two roles in anterior-posterior axis specification. First, Of'hb is required to suppress abdominal identity in the gnathal and thoracic regions. Subsequently, it is then required for proper germband growth and segmentation. In milkweed bug embryos depleted for hunchback, these two effects result in animals in which a relatively normal head is followed by several segments with abdominal identity. This phenotype is reminiscent to that found in Drosophila hunchback mutants, but in Oncopeltus is generated through the combination of the two separate defects.