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A Lipid-Peptide Microbicide Inactivates Herpes Simplex Virus. Charles E. Isaacs, 2004.A microbicide combining the lipid-ether 1-0-octyl-sn-glycerol (OG; 3 mM) and peptide D2A21 (9 µM) reduced herpes simplex virus type 1 (HSV-1) and HSV-2 titers by at least 1,000-fold, more than the sum of the inactivations produced by OG and D2A21 alone . OG plus D2A21 reduced HSV-1 and HSV-2 titers by  1,000-fold in
 10 and
20 min, respectively, whereas OG and D2A21 used alone produced almost no virus inactivation during these times .
A Single Species, Micromonas pusilla (Prasinophyceae), Dominates the Eukaryotic Picoplankton in the Western English Channel. Fabrice Not, 2004.The class Prasinophyceae (Chlorophyta) contains several photosynthetic picoeukaryotic species described from cultured isolates . The ecology of these organisms and their contributions to the picoeukaryotic community in aquatic ecosystems have received little consideration . We have designed and tested eight new 18S ribosomal DNA oligonucleotide probes specific for different Prasinophyceae clades, genera, and species . Using fluorescent in situ hybridization associated with tyramide signal amplification, these probes, along with more general probes, have been applied to samples from a marine coastal site off Roscoff (France) collected every 2 weeks between July 2000 and September 2001 . The abundance of eukaryotic picoplankton remained high (>103 cells ml–1) during the sampling period, with maxima in summer (up to 2 x 104 cells ml–1), and a single green algal species, Micromonas pusilla (Prasinophyceae), dominated the community all year round . Members of the order Prasinococcales and the species Bathycoccus prasinos (Mamiellales) displayed sporadic occurrences, while the abundances of all other Prasinophyceae groups targeted remained negligible . Two Proteins with Ornithine Acetyltransferase Activity Show Different Functions in Streptomyces clavuligerus: Oat2 Modulates Clavulanic Acid Biosynthesis in Response to Arginine. A. de la Fuente, 2004.The oat2 gene, located in the clavulanic acid gene cluster in Streptomyces clavuligerus, is similar to argJ, which encodes N-acetylornithine:glutamic acid acetyltransferase activity . Purified proteins obtained by expression in Escherichia coli of the argJ and oat2 genes of S . clavuligerus posses N-acetyltransferase activity . The kinetics and substrate specificities of both proteins are very similar . Deletion of the oat2 gene did not affect the total N-acetylornithine transferase activity and slightly reduced the formation of clavulanic acid under standard culture conditions . However, the oat2 mutant produced more clavulanic acid than the parental strain in cultures supplemented with high levels (above 1 mM) of arginine . The purified S . clavuligerus ArgR protein bound the arginine box in the oat2 promoter, and the expression of oat2 was higher in mutants with a disruption in argR (arginine-deregulated), confirming that the Arg boxes of oat2 are functional in vivo . Our results suggest that the Oat2 protein or one of its reaction products has a regulatory role that modulates clavulanic acid biosynthesis in response to high arginine concentrations . A Flow-Cytometric Gram-Staining Technique for Milk-Associated Bacteria. Claus Holm, 2003.A Gram-staining technique combining staining with two fluorescent stains, Oregon Green-conjugated wheat germ agglutinin (WGA) and hexidium iodide (HI) followed by flow-cytometric detection is described . WGA stains gram-positive bacteria while HI binds to the DNA of all bacteria after permeabilization by EDTA and incubation at 50°C for 15 min . For WGA to bind to gram-positive bacteria, a 3 M potassium chloride solution was found to give the highest fluorescence intensity . A total of 12 strains representing some of the predominant bacterial species in bulk tank milk and mixtures of these were stained and analyzed by flow cytometry . Overall, the staining method showed a clear differentiation between gram-positive and gram-negative bacterial populations . For stationary-stage cultures of seven gram-positive bacteria and five gram-negative bacteria, an average of 99% of the cells were correctly interpreted . The method was only slightly influenced by the growth phase of the bacteria or conditions such as freezing at -18°C for 24 h . For any of these conditions, an average of at least 95% of the cells were correctly interpreted . When stationary-stage cultures were stored at 5°C for 14 days, an average of 86% of the cells were correctly interpreted . The Gram-staining technique was applied to the flow cytometry analysis of bulk tank milk inoculated with Staphylococcus aureus and Escherichia coli . These results demonstrate that the technique is suitable for analyzing milk samples without precultivation . Factors Influencing the Chlorine Susceptibility of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum. Joseph O. Falkinham III, 2003.The susceptibility of representative strains of Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum (the MAIS group) to chlorine was studied to identify factors related to culture conditions and growth phase that influenced susceptibility . M . avium and M . intracellulare strains were more resistant to chlorine than were strains of M . scrofulaceum . Transparent and unpigmented colony variants were more resistant to chlorine than were their isogenic opaque and pigmented variants (respectively) . Depending on growth stage and growth rate, MAIS strains differed in their chlorine susceptibilities . Cells from strains of all three species growing in early log phase at the highest growth rates were more susceptible than cells in log and stationary phase . Rapidly growing cells were more susceptible to chlorine than slowly growing cells . The chlorine susceptibility of M . avium cells grown at 30°C was increased when cells were exposed to chlorine at 40°C compared to susceptibility after exposure at 30°C . Cells of M . avium grown in 6% oxygen were significantly more chlorine susceptible than cells grown in air . Chlorine-resistant MAIS strains were more hydrophobic and resistant to Tween 80, para-nitrobenzoate, hydroxylamine, and nitrite than were the chlorine-sensitive strains .
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