Daniel D. Isaac

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The trachealess (trh) gene of Drosophila is required for embryonic tube formation. In trh mutants, tube-forming cells of the salivary gland, trachea, and filzkörper fail to invaginate to form tubes and remain on the embryo surface. We identified a P-element insertion that disrupts trh function and used the insert to clone and characterize trh. trh is(More)
Salivary gland formation in the Drosophila embryo is linked to the expression of the homeotic gene Sex combs reduced (Scr). When Scr function is missing, salivary glands do not form, and when SCR is expressed everywhere, salivary glands form in new places. However, not every cell that expresses Scr is recruited to a salivary gland fate. Along the(More)
In Escherichia coli, the CpxR/A two-component system senses various types of extracytoplasmic stresses and responds by activating the expression of genes encoding periplasmic protein folding and trafficking factors that clear such stresses to ensure the organism's survival. The cpxP gene encodes a small, stress-combative periplasmic protein and is the most(More)
Protein kinase B (PKB, also termed Akt) is a phosphatidylinositol 3' kinase (PI3'K)-dependent enzyme implicated in survival signaling and human tumorigenesis. To identify potential targets of this protein kinase, we employed a genetic screen in Drosophila. Among several genes that genetically interacted with PKB was trachealess (trh), which encodes a(More)
Advanced techniques for observing protein localization in live bacteria show that the distributions are dynamic. For technical reasons, most such techniques have not been applied to outer membrane proteins in Gram-negative bacteria. We have developed two novel live-cell imaging techniques to observe the surface distribution of LamB, an abundant integral(More)
The Drosophila salivary gland is a simple tubular organ derived from a contiguous epithelial primordium, which is established by the activities of the homeodomain-containing proteins Sex combs reduced (SCR), Extradenticle (EXD), and Homothorax (HTH). EGF signaling along the ventral midline specifies the salivary duct fate for cells in the center of the(More)
A 61-residue cholecystokinin-releasing peptide (monitor peptide), which was obtained from rat pancreatic juice and found to stimulate pancreatic enzyme secretion, was recently reported to inhibit bovine trypsin and to possess epidermal growth factor (EGF)-like activities, at a concentration of about 10 nM. However, monitor peptide is structurally different(More)
Studies of Drosophila salivary gland formation have elucidated the regulatory pathway by which the salivary gland fate is determined and the morphogenetic processes by which the primordial cells are internalized to form the tubular glands. Both the position of the salivary primordia and the number of cells recruited to a salivary gland fate are established(More)
The protein-tyrosine kinase gene Itk is expressed preferentially in T lymphoid cells of the mouse and is induced by IL-2. A related gene, Btk, is expressed in the murine B lymphoid and myeloid lineages. Because mutations in Btk and the corresponding human gene are associated with X-linked immunodeficiency syndromes, it was of interest to map Itk and its(More)