EMBYONIC SALIVARY GLAND DEVELOPMENT IN DROSPHILA

果蝇唾液腺的胚胎发育为 对参与测定和分析的基因进行分析的几个优点 差异化。在胚带延伸胚胎的外胚层中， 腺体在一个特定的位置开始发育，在几个 已知的模式调控基因。然后，差异化发生在几个 小时，这意味着从承诺到 差异化。 最近的工作提出了一种最初的唾液胎盘模型 既牵涉到前后部也牵涉到背腹部的判断 在唾液发育的这第一步中形成模式的基因。我们不是 我想确定两种基因，这个模型预测的可能是 参与了决定，我们想要开始研究 唾液发育后期的其他基因。 三个影响背腹模式的基因将被测试 对胎盘形成的积极影响，并将开始搜索 调控基因fkh的基因最早在 发育中的胎盘。因为很明显细胞-细胞相互作用是 在胎盘形成和进一步发育中很重要，缺乏突变体或 有异常模式的EGF同源物，如Notch或Delta将是 测试对胎盘结构或其随后的内陷的影响。 由于胎盘内陷的信号似乎起源于 后缘的胎盘，节段的极性基因就像无翼的那样 对于副节段的后部进行测试是必要的 对内陷的影响。两个基因Toll和Dsrc28C可能与此有关 在将此信号传播到Placode的其余部分时，将通过 以异位的方式在整个地方表达它们。 将使用一种标记发育中胚胎中特定细胞的方法 以确定地块形成后是否有其他单元格加入 并定位唾液导管细胞的前体。形成的组织 还将检查是否存在锯齿状突变型胚胎或突变的基因。 斯皮茨小组，这两个小组都可能参与区分 腺体和导管细胞。

The embryonic development of the Drosophila salivary glands provides several advantages for analysis of the genes involved in determination and differentiation. In the ectoderm of the germ band extended embryo, the glands begin development at a defined position under the control of several known pattern regulating genes. Differentiation then occurs within a few hours, implying that there are few steps leading from commitment to differentiation. Recent work has suggested a model for initial salivary placode determination that implicates both anterior-posterior and dorsal-ventral pattern forming genes in this initial step in salivary development. We not want to identify two kinds of genes that this model predicts may be involved in determination, and we want to begin examining the roles of additional genes in the later stages of salivary development. Three genes that affect dorsal-ventral patterning will be tested for positive effects on placode formation and a search will be started for genes that regulate the gene, fkh, that is expressed earliest in the developing placode. Since it is clear that cell-cell interactions are important in placode formation and further development, mutants lacking or having abnormal patterns of EGF homologues like Notch or Delta will be tested for effects on placode structure or on its subsequent invagination. Since the signal for placode invagination appears to originate from the posterior margin of the placode, segment polarity genes like wingless that are necessary for the posterior part of the parasegment will be tested for effects on invagination. Two genes, Toll and Dsrc28C, that may be involved in spreading this signal to the rest of the placode will be tested by expressing them ectopically throughout the placode. A method for marking particular cells in the developing embryo will be used to determine whether additional cells join the placode after it is formed and to locate the precursors for salivary duct cells. Formation of the ducts will also be examined in embryos mutant for Serrate or for genes of the spitz group, both of which may be involved in distinguishing between gland and duct cells.