Host-selected mutations converging on a global regulator drive an adaptive leap towards symbiosis in bacteria.

Host immune and physical barriers protect against pathogens but also impede the establishment of essential symbiotic partnerships. To reveal mechanisms by which beneficial organisms adapt to circumvent host defenses, we experimentally evolved ecologically distinct bioluminescent by colonization and growth within the light organs of the squid . Serial squid passaging of bacteria produced eight distinct mutations in the sensor kinase gene, which conferred an exceptional selective advantage that could be demonstrated through both empirical and theoretical analysis.

Environmental Conditions Associated with Elevated Vibrio parahaemolyticus Concentrations in Great Bay Estuary, New Hampshire.

Reports from state health departments and the Centers for Disease Control and Prevention indicate that the annual number of reported human vibriosis cases in New England has increased in the past decade. Concurrently, there has been a shift in both the spatial distribution and seasonal detection of Vibrio spp. throughout the region based on limited monitoring data.

Mycobacterial Esx-3 requires multiple components for iron acquisition.

ABSTRACT The type VII secretion systems are conserved across mycobacterial species and in many Gram-positive bacteria. While the well-characterized Esx-1 pathway is required for the virulence of pathogenic mycobacteria and conjugation in the model organism Mycobacterium smegmatis, Esx-3 contributes to mycobactin-mediated iron acquisition in these bacteria. Here we show that several Esx-3 components are individually required for function under low-iron conditions but that at least one, the membrane-bound protease MycP3 of M.

Metabolic and bactericidal effects of targeted suppression of NadD and NadE enzymes in mycobacteria.

Unlabelled: Mycobacterium tuberculosis remains a major cause of death due to the lack of treatment accessibility, HIV coinfection, and drug resistance. Development of new drugs targeting previously unexplored pathways is essential to shorten treatment time and eliminate persistent M. tuberculosis.

Tryptophan biosynthesis protects mycobacteria from CD4 T-cell-mediated killing.

Bacteria that cause disease rely on their ability to counteract and overcome host defenses. Here, we present a genome-scale study of Mycobacterium tuberculosis (Mtb) that uncovers the bacterial determinants of surviving host immunity, sets of genes we term "counteractomes." Through this analysis, we found that CD4 T cells attempt to contain Mtb growth by starving it of tryptophan--a mechanism that successfully limits infections by Chlamydia and Leishmania, natural tryptophan auxotrophs.

Influence of seasonality on the genetic diversity of Vibrio parahaemolyticus in New Hampshire shellfish waters as determined by multilocus sequence analysis.

Risk of gastric infection with Vibrio parahaemolyticus increases with favorable environmental conditions and population shifts that increase prevalence of infective strains. Genetic analysis of New Hampshire strains revealed a unique population with some isolates similar to outbreak-causing strains and high-level diversity that increased as waters warmed.

Ecology and genetic structure of a northern temperate Vibrio cholerae population related to toxigenic isolates.

Although Vibrio cholerae is an important human pathogen, little is known about its populations in regions where the organism is endemic but where cholera disease is rare. A total of 31 independent isolates confirmed as V. cholerae were collected from water, sediment, and oysters in 2008 and 2009 from the Great Bay Estuary (GBE) in New Hampshire, a location where the organism has never been detected.

Antimicrobial principle from Aframomum longifolius.

Antimicrobial activity-directed fractionation of the seeds of Aframomum longifolius (Zingiberaceae) afforded two new labdane-type diterpenoids, 15-hydroxy-15-methoxylabda-8(17), 12( E)-dien-16-al (aframolin A) ( 1) and 8beta(17)-epoxy-15,15-dimethoxylabd-12( E)-en-16-al (aframolin B) ( 2), together with the known diterpenes labda-8(17),12( E)-diene-15,16-dial ( 3) and aframodial ( 4). Their structures were determined by spectroscopic methods. Compound 4 showed significant antimicrobial activity against Cryptococcus neoformans, Staphylococcus aureus and methicillin-resistant S.

Novel antimicrobial diterpenoids from Turraeanthus africanus.

The dichloromethane-methanol (1/1) extract of the stem bark of Turraeanthus africanus (Meliaceae) showed remarkable antimicrobial activity against Cryptococcus neoformans, Staphylococcus aureus and methicillin-resistant S. aureus. Phytochemical investigation of this extract afforded six new diterpenoid derivatives, (+)-16-acetoxy-12,15-epoxylabda-8(17),12,14-triene ( 3), [16( E),12 S,15 R]-16-acetoxy-12,15-epoxy-15-isopropoxy- ent-labda-8(17),13(16)-diene (turraeanin A, 4), [16( E),12 R,15 S]-16-acetoxy-12,15-epoxy-15-isopropoxy- ent-labda-8(17),13(16)-diene (turraeanin B, 5), [16( E),12 S,15 R]-16-acetoxy-12,15-epoxy-15-methoxy- ent-labda-8(17),13(16)-diene (turraeanin C, 6), [16( E),12 R,15 S]-16-acetoxy-12,15-epoxy-15-methoxy- ent-labda-8(17),13(16)-diene (turraeanin D, 7) and (12 S,13 S,15 R)-12,15-epoxy-15-methoxy- ent-labd-8(17)-en-16-al (turraeanin E, 9) together with the known compounds, 15,16-epoxy- ent-labda-8(17),13(16),14-triene ( 1), (+)-pumiloxide ( 2), ent-labda-8(17),12 ( E)-diene-15,16-dial ( 8) and 16-acetoxy-12( R),15-epoxy-15beta-hydroxylabda-8(17),13 (16)-diene ( 10).

Tabouensinium chloride, a novel quaternary pyranoquinoline alkaloid from Araliopsis tabouensis.

A novel pyranoquinoline alkaloid 3,4-dihydro-3-hydroxy-5-methoxy-2,2,10-trimethylpyrano [2,3-b]quinoline named tabouensinium chloride (1), was isolated from the stem bark of Araliopsis tabouensis along with twelve known quinoline alkaloids. In addition, the known flindisol, lupeol and beta-sitosterol glucoside were also identified. Their structures were deduced from spectral data.

Antiplasmodial agents from the leaves of Glossocalyx brevipes.

A phytochemical study of the methylene chloride/methanol (1/1) extract of the leaves of Glossocalyx brevipes Benth. (Monimiaceae) afforded three new derivatives of homogentisic acid, methyl 2-(1'beta-geranyl-5'beta-hydroxy-2'-oxocyclohex-3'-enyl)acetate (1), 2-(1'beta-geranyl-5'beta-hydroxy-2'-oxocyclohex-3'-enyl)acetic acid (2), methyl 2-(1'beta-geranyl-5'beta-hydroxy-4'beta-methoxy-2'-oxocyclohexyl)acetate (3), and two known alkaloids, aristololactam BII and liriodenine. Compounds 1 and 2 and liriodenine showed modest in vitro activity against Plasmodium falciparum.