No abstract

The four divergent serotypes of dengue virus are the causative agents of dengue fever, dengue hemorrhagic fever and dengue shock syndrome. About two-fifths of the world's population live in areas where dengue is prevalent, and thousands of deaths are caused by the viruses every year. Dengue virus is transmitted from one person to another primarily by the yellow fever mosquito, Aedes aegypti. Recent studies have begun to define how the dengue viral proteins interact with host proteins to mediate viral replication and pathogenesis. A combined analysis of these studies, however, suggests that many virus-host protein interactions remain to be identified, especially for the mosquito host. In this study, we used high-throughput yeast two-hybrid screening to identify mosquito and human proteins that physically interact with dengue proteins. We tested each identified host protein against the proteins from all four serotypes of dengue to identify interactions that are conserved across serotypes. We further confirmed many of the interactions using co-affinity purification assays. As in other large-scale screens, we identified some previously detected interactions and many new ones, moving us closer to a complete host – dengue protein interactome. To help summarize and prioritize the data for further study, we combined our interactions with other published data and identified a subset of the host-dengue interactions that are now supported by multiple forms of evidence. These data should be useful for understanding the interplay between dengue and its hosts and may provide candidates for drug targets and vector control strategies.

An extracellular nuclease produced by Staphylococcus aureusl-3 has been shown to contain 149 amino acid residues (mol wt, 16,807) and to lack both sulfhydryl groups and disulfide bonds ( Fig. 1).3-5 The enzyme catalyzes the cleavage of both DNA and RNA to yield 3'-nucleotides.2' I The absolute requirement for Ca++ l, 2, 6 may be explained by the interdependency of Ca++ and nucleotide binding to the protein, and the conformation of the enzyme is stabilized by this reversible ligand interaction.7' 8 The present communication summarizes experiments on the cleavage of the polypeptide chain by limited digestion with trypsin in the presence of 3',5'-deoxythymidine-diphosphate to yield three peptide fragments:

No abstract

A modification of previously described methods of electron microscopic gene mapping and of gene enrichment based on the avidin-biotin interaction is presented. The modification consists of coupling cytochrome-c instead of pentane diamine to the oxidized 2', 3' terminus of an RNA by Schiff base formation and BH-4 reduction. The RNA-cytochrome-c conjugate is purified by a simple chromatographic procedure; several biotins are attached to the cytochrome moiety by acylation. The extended arm between biotin and RNA gives efficient electron microscopic gene mapping of DNA:RNA-biotin hybrids with avidin-ferritin and avidin-polymethacylate sphere labels and efficient gene enrichment by buoyant banding of DNA:RNA-biotin:avidin-spheres in CsCl. A 1400 fold enrichment (thus, 25% pure) and a 90% yield of long Drosophila DNA strands with 5S RNA genes is achieved.

No abstract

Ingestion of a blood meal by the female mosquito Anopheles gambiae (L., Diptera: Culicidae), results in a dramatic distention of the midgut epithelium. Here we report that these events correlate with a transient increase of actin mRNA and protein abundance. The newly synthesized actin may provide a pool of actin protein needed to remodel epithelial cell cytoarchitecture. We also document changes in midgut epithelial cell morphology. Upon blood ingestion, the columnar cells flatten accompanied by the loss of microvilli on the lumenal side and the unfolding of the labyrinth on the basal side. These changes correlate with the large increase of epithelial surface area needed to accommodate the blood meal. Actin gene expression, actin synthesis and cell morphology all return to the prefeeding state by 24 h after blood intake.

No abstract