EMBYONIC SALIVARY GLAND DEVELOPMENT IN DROSPHILA

果蝇唾液腺的胚胎发育 分析参与确定的基因的几个优点， 分化 在胚带延伸胚的外胚层中， 腺体开始发育在一个确定的位置下的控制下， 已知的模式调节基因。 然后，在几个 小时，这意味着从承诺到 分化 最近的工作提出了一个初始唾液基板的模型 涉及前后和背腹的确定 在唾液发育的最初阶段，基因的模式形成。 我们不 我想确定两种基因，这个模型预测可能是 参与决定，我们想开始检查的作用， 唾液发育后期的额外基因。 三个影响背腹图案的基因将被测试， 积极影响基板形成和搜索将开始 调节fkh基因的基因，fkh基因最早表达于 发育基板。 因为很明显细胞间的相互作用 在基板的形成和进一步发展，突变体缺乏或 有异常模式的EGF同系物，如缺口或三角洲将 测试对基板结构或其随后的内陷的影响。 由于基板内陷的信号似乎来源于 基板的后缘，裂片极性基因像无翅的， 将对parsegment的后部进行测试， 对内陷的影响 Toll和Dsrc28C两个基因可能参与了 在将该信号传播到基板的其余部分时， 在整个基板异位表达。 将使用一种标记发育中胚胎中特定细胞的方法 以确定在基板形成之后是否有另外的单元加入基板 并定位唾液腺导管细胞的前体。 形成 还将在胚胎中检查Serrate突变体或 斯皮茨小组，这两个小组都可能参与区分 腺和导管细胞。

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.