Plc1p is required for SAGA recruitment and derepression of Sko1p-regulated genes

In Saccharomyces cerevisiae, many osmotically inducible genes are regulated by the Sko1p-Ssn6p-Tup1p complex. On osmotic shock, the MAP kinase Hog1p associates with this complex, phosphorylates Sko1p, and converts it into an activator that subsequently recruits Swi/Snf and SAGA complexes. We have found that phospholipase C (Plc1p encoded by PLC1) is required for derepression of Sko1p-Ssn6p-Tup1p-controlled osmoinducible genes upon osmotic shock. Although plc1Delta mutation affects the assembly of the preinitiation complex after osmotic shock, it does not affect the recruitment of Hog1p and Swi/Snf complex at these promoters. However, Plc1p facilitates osmotic shock-induced recruitment of the SAGA complex. Like plc1Delta cells, SAGA mutants are osmosensitive and display compromised expression of osmotically inducible genes. The reduced binding of SAGA to Sko1p-Ssn6p-Tup1p-repressed promoters in plc1Delta cells does not correlate with reduced histone acetylation. However, SAGA functions at these promoters to facilitate recruitment of the TATA-binding protein. The results thus provide evidence that Plc1p and inositol polyphosphates affect derepression of Sko1p-Ssn6p-Tup1p-controlled genes by a mechanism that involves recruitment of the SAGA complex and TATA-binding protein.     

Synthesis and bio-evaluation of aryl hydrazono esters for oviposition responses in Aedes albopictus

A novel series of aryl hydrazono esters (AHE) (1-13) were synthesized (yield 76-98%) to study the oviposition responses in Aedes albopictus (Skuse) mosquitoes for the first time. At a concentration of 10 μg ml⁻¹ in dual choice experiment, among the screened compounds, AHE-12 showed remarkable oviposition attractant activity with an oviposition activity index (OAI) of +0.299 (greater than 95% confidence limit) comparable to p-cresol (OAI +0.320) which is well-reported oviposition attractant for Aedes aegypti. Conversely, AHE-10 exhibited highest oviposition deterrent activity with OAI −0.247. The possible utilization of these compounds will be in integrated vector management strategies.     

Chronic granulomatous disease: a review of the infectious and inflammatory complications

Chronic Granulomatous Disease is the most commonly encountered immunodeficiency involving the phagocyte, and is characterized by repeated infections with bacterial and fungal pathogens, as well as the formation of granulomas in tissue. The disease is the result of a disorder of the NADPH oxidase system, culminating in an inability of the phagocyte to generate superoxide, leading to the defective killing of pathogenic organisms. This can lead to infections with Staphylococcus aureus, Psedomonas species, Nocardia species, and fungi (such as Aspergillus species and Candida albicans). Involvement of vital or large organs can contribute to morbidity and/or mortality in the affected patients. Major advances have occurred in the diagnosis and treatment of this disease, with the potential for gene therapy or stem cell transplantation looming on the horizon.     

Role of stress fibers in the association of intermediate filaments with microtubules in fibroblast cells.

The association between intermediate filaments (IF) and microtubules (MT) has been demonstrated by several experiments using MT inhibitors and by microinjecting specific antibodies. The actin cytoskeleton has recently been assigned a role in this process of drug induced IF collapse. However, this was not found to be true in large cells with irregular morphology. For instance, in early passage diploid fibroblasts of human origin and in armadillo cell lines, where the cells are large, irregular in shape and exhibit prominent stress fibers ( SF ), depolymerization of MT with nocodazole did not lead to collapse of IF . Instead, the IF formed bundles of coils that seemed to associate with the SF . Disintegration of the SF with cytochalasin B led to the collapse of the IF . It appears that the actin organization in such large cells with extensive SF , is not as contractile as in typical spindle shaped fibroblasts which have relatively less stable actin organization. The stable SF may actually prevent IF collapse.     

Tracheal branch repopulation precedes induction of the Drosophila dorsal air sac primordium

The dorsal air sacs supply oxygen to the flight muscles of the Drosophila adult. This tracheal organ grows from an epithelial tube (the air sac primordium (ASP)) that arises during the third larval instar (L3) from a wing-disc-associated tracheal branch. Since the ASP is generated by a program of both morphogenesis and cell proliferation and since the larval tracheal branches are populated by cells that are terminally differentiated, the provenance of its progenitors has been uncertain. Here, we show that, although other larval tracheae are remodeled after L3, most tracheal branches in the tracheal metamere associated with the wing disc (Tr2) are precociously repopulated with imaginal tracheoblasts during L3. Concurrently, the larval cells in Tr2 undergo head involution defective (hid)-dependent programmed cell death. In BX-C mutant larvae, the tracheal branches of the Tr3 metamere are also repopulated during L3. Our results show that repopulation of the larval trachea is a prerequisite for FGF-dependent induction of cell proliferation and tubulogenesis in the ASP and that homeotic selector gene function is necessary for the temporal and spatial control of tracheal repopulation.