Halogenated furanones inhibit quorum sensing through accelerated LuxR turnover.

N-acyl-L-homoserine lactones (AHLs) are co-regulatory ligands required for control of the expression of genes encoding virulence traits in many Gram-negative bacterial species. Recent studies have indicated that AHLs modulate the cellular concentrations of LuxR-type regulatory proteins by binding and fortifying these proteins against proteolytic degradation (Zhu & Winans, 2001 ). Halogenated furanones produced by the macroalga Delisea pulchra inhibit AHL-dependent gene expression.

Phenotypic and genotypic analysis of Helicoverpa armigera nucleopolyhedrovirus serially passaged in cell culture.

Rapid accumulation of few polyhedra (FP) mutants was detected during serial passaging of Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) in cell culture. 100% FP infected cells were observed by passage 6. The specific yield decreased from 178 polyhedra per cell at passage 2 to two polyhedra per cell at passage 6.

Gill-associated nidovirus of Penaeus monodon prawns transcribes 3'-coterminal subgenomic mRNAs that do not possess 5'-leader sequences.

Sequence analysis of the approximately 20 kb 5'-terminal portion of the ssRNA genome of gill-associated virus (GAV) of Penaeus monodon prawns has previously established that it contains an ORF1a-1b replicase gene equivalent to those of the coronavirus and arterivirus members of the order Nidovirales. Sequence analysis of the remaining approximately 6.2 kb of the GAV genome downstream of ORF1a-1b to a 3'-poly(A) tail has identified two highly conserved intergenic sequences in which 29/32 nucleotides are conserved.

Respiratory syncytial virus matrix protein associates with nucleocapsids in infected cells.

Little is known about the functions of the matrix (M) protein of respiratory syncytial virus (RSV). By analogy with other negative-strand RNA viruses, the M protein should inhibit the viral polymerase prior to packaging and facilitate virion assembly. In this study, localization of the RSV M protein in infected cells and its association with the RSV nucleocapsid complex was investigated.

Polymorphism of open reading frame 71 of equine herpesvirus-4 (EHV-4) and EHV-1.

Open reading frame (ORF) 71 genes of both equine herpesvirus-1 (EHV-1) and EHV-4 encode a unique glycoprotein, which has been described to vary in molecular mass from 200 to 450 kDa. Using PCR and nucleotide sequence analysis, it was shown that the ORF 71 genes of EHV-1 and EHV-4 are polymorphic due to a variable number of reiterated sequences in two regions, designated regions A and B. Region A was threonine-rich and was located near the N terminus.

Control of dimethylsulfoxide reductase expression in Rhodobacter capsulatus: the role of carbon metabolites and the response regulators DorR and RegA.

Regulation of the expression of dimethylsulfoxide (DMSO) reductase was investigated in the purple phototrophic bacterium Rhodobacter capsulatus. Under phototrophic, anaerobic conditions with malate as carbon source, DMSO caused an approximately 150-fold induction of DMSO reductase activity. The response regulator DorR was required for DMSO-dependent induction and also appeared to slightly repress DMSO reductase expression in the absence of substrate.

Role of spoT-dependent ppGpp accumulation in the survival of light-exposed starved bacteria.

In bacteria, cytoplasmic levels of the effector nucleotide ppGpp are regulated in response to changes in growth conditions. This study describes the involvement of SpoT-mediated ppGpp accumulation in the survival of light-exposed bacteria during fatty acid starvation. In contrast to isogenic wild-type strains and relA mutants, the 'Vibrio angustum' S14 spoT and Escherichia coli relA spoT mutants displayed significant losses in viability in response to cerulenin-induced fatty acid starvation under cool-white fluorescent light.

Role of the C-terminal YG repeats of the primer-dependent streptococcal glucosyltransferase, GtfJ, in binding to dextran and mutan.

The recombinant primer-dependent glucosyltransferase GtfJ of Streptococcus salivarius possesses a C-terminal glucan-binding domain composed of eighteen 21 aa YG repeats. By engineering a series of C-terminal truncated proteins, the position at which truncation prevented further mutan synthesis was defined to a region of 43 aa, confirming that not all of the YG motifs were required for the formation of mutan by GtfJ. The role of the YG repeats in glucan binding was investigated in detail.

Fusobacterium nucleatum supports the growth of Porphyromonas gingivalis in oxygenated and carbon-dioxide-depleted environments.

The authors compared the differences in tolerance to oxygen of the anaerobic periodontopathic bacteria Fusobacterium nucleatum and Porphyromonas gingivalis, and explored the possibility that F. nucleatum might be able to support the growth of P. gingivalis in aerated and CO2-depleted environments.

Assessment of foreign protein production by recombinant Heliothis (Helicoverpa) armigera entomopoxviruses in Spodoptera frugiperda cells.

This report describes the first production of recombinant forms of Heliothis (Helicoverpa) armigera entomopoxvirus (HaEPV). These HaEPVs are engineered at either the spheroidin or fusolin locus, to produce the green fluorescent marker protein (GFP). The growth properties of these recombinant HaEPVs, in comparison to the parental HaEPV, were assessed in cultured Spodoptera frugiperda Sf9 cells.

Determination of bacterial load by real-time PCR using a broad-range (universal) probe and primers set.

The design and evaluation of a set of universal primers and probe for the amplification of 16S rDNA from the Domain Bacteria to estimate total bacterial load by real-time PCR is reported. Broad specificity of the universal detection system was confirmed by testing DNA isolated from 34 bacterial species encompassing most of the groups of bacteria outlined in Bergey's Manual of Determinative Bacteriology. However, the nature of the chromosomal DNA used as a standard was critical.

Nucleotide sequence analysis of a novel circovirus of canaries and its relationship to other members of the genus Circovirus of the family Circoviridae.

The circular, single-stranded DNA genome of a novel circovirus of canaries, tentatively named canary circovirus (CaCV), was cloned and sequenced. Sequence analysis indicated that the genome was 1952 nucleotides (nt) in size and had the potential to encode three viral proteins, including the putative capsid and replication-associated (Rep) proteins. The CaCV genome shared greatest sequence similarity (58.

Equine rhinitis B virus: a new serotype.

Equine rhinovirus serotype 3 isolate P313/75 was assigned, with an unclassified genus status, to the family PICORNAVIRIDAE: The sequence from the 5' poly(C) tract to the 3' poly(A) tract of P313/75 was determined. The sequence is 8821 bases in length and contains a potential open reading frame for a polyprotein of 2583 amino acids. Sequence comparison and phylogenic analysis suggest that P313/75 is most closely related to the prototype equine rhinitis B virus (ERBV) strain P1436/71, formerly named equine rhinovirus type 2.

Genomic analysis of the erythromycin resistance element Tn5398 from Clostridium difficile.

Clostridium difficile is a nosocomial pathogen that causes a range of chronic intestinal diseases, usually as a result of antimicrobial therapy. Macrolide-lincosamide-streptogramin B (MLS) resistance in C. difficile is encoded by the Erm B resistance determinant, which is thought to be located on a conjugative transposon, Tn5398.

The novel picornavirus Equine rhinitis B virus contains a strong type II internal ribosomal entry site which functions similarly to that of Encephalomyocarditis virus.

Equine rhinitis B virus (ERBV) has recently been classified as an Erbovirus, a new genus in the Picornaviridae family. ERBV is distantly related to members of the Cardiovirus and Aphthovirus genera which utilize a type II internal ribosome entry sequence (IRES) to initiate translation. We show that ERBV also possesses the core stem-loop structures (H-L) of a type II IRES.

Determination of the intramolecular disulfide bond arrangement and biochemical identification of the glycosylation sites of the nonstructural protein NS1 of Murray Valley encephalitis virus.

The 12 cysteine residues in the flavivirus NS1 protein are strictly conserved, suggesting that they form disulfide bonds that are critical for folding the protein into a functional structure. In this study, we examined the intramolecular disulfide bond arrangement of NS1 of Murray Valley encephalitis virus and elucidated three of the six cysteine-pairing arrangements. Disulfide linkages were identified by separating tryptic-digested NS1 by reverse-phase high pressure liquid chromatography and analysing the resulting peptide peaks by protein sequencing, amino acid analysis and/or electrospray mass spectrometry.

The cryptic ushA gene (ushA(c)) in natural isolates of Salmonella enterica (serotype Typhimurium) has been inactivated by a single missense mutation.

Two mutational mechanisms, both supported by experimental studies, have been proposed for the evolution of new or improved enzyme specificities in bacteria. One mechanism involves point mutation(s) in a gene conferring novel substrate specificity with partial or complete loss of the original (wild-type) activity of the encoded product. The second mechanism involves gene duplication followed by silencing (inactivation) of one of these duplicates.

Repeated ruminal dosing of Ruminococcus spp. does not result in persistence, but changes in other microbial populations occur that can be measured with quantitative 16S-rRNA-based probes.

Digestibility of fibre in ruminants may be improved by the introduction of highly fibrolytic strains of ruminal bacteria. This approach may be feasible if, for example, strains of Ruminococcus that are significantly more fibrolytic than the normal population of Ruminococcus are used for inoculation purposes. Introduced strains of bacteria, irrespective of ecosystem, often decline after inoculation, and in this study, highly fibrolytic strains of Ruminococcus were continuously dosed to ensure that measurements of fibre digestion were made in the presence of significant numbers of the introduced bacteria.

Equine rhinitis A virus: structural proteins and immune response.

Equine rhinitis A virus (ERAV) is a picornavirus that has been reclassified as a member of the Aphthovirus genus because of its resemblance to foot-and-mouth disease virus at the level of nucleotide sequence and overall genomic structure. The N-terminal amino acid sequence of three of the four capsid proteins of ERAV was determined and showed that the proteolytic cleavage sites within the precursor P1 polypeptide occur exactly as those predicted for an aphthovirus-like 3C protease, which generates the capsid proteins VP1 and VP3. However, the autocatalytic cleavage site between VP4 and VP2, which is independent of 3C protease cleavage, was different from that predicted previously.

Effect of hydrolysable and condensed tannins on growth, morphology and metabolism of Streptococcus gallolyticus (S. caprinus) and Streptococcus bovis.

Streptococcus gallolyticus (S. caprinus) was resistant in vitro to at least 7% (w/v) tannic acid and 4% (w/v) acacia condensed tannin, levels 10-fold greater than those tolerated by S. bovis.

A new simvastatin (mevinolin)-resistance marker from Haloarcula hispanica and a new Haloferax volcanii strain cured of plasmid pHV2.

The mevinolin-resistance determinant, hmg, encodes the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and is a commonly used selectable marker in halobacterial genetics. Plasmids bearing this marker suffer from instability in Haloferax volcanii because the resistance gene was derived from the genome of this species and is almost identical in sequence to the chromosomal copy. In order to reduce the level of homologous recombination between introduced plasmid vectors and the chromosome of Haloferax, a homologue of the hmg determinant was obtained from the distantly related organism, Haloarcula hispanica.

Type IV O antigen modification genes in the genome of Shigella flexneri NCTC 8296.

The genes encoding type IV O antigen glucosylation were characterized from both Escherichia coli and Shigella flexneri. The putative O antigen modification genes from E. coli, o120 o306 o443, were PCR-amplified and introduced into S.

A small region of the dengue virus-encoded RNA-dependent RNA polymerase, NS5, confers interaction with both the nuclear transport receptor importin-beta and the viral helicase, NS3.

The dengue virus RNA-dependent RNA polymerase, NS5, and the protease/helicase, NS3, are multidomain proteins that have been shown to interact both in vivo and in vitro. A hyperphosphorylated form of NS5 that does not interact with NS3 has been detected in the nuclei of virus-infected cells, presumably as the result of the action of a functional nuclear localization sequence within the interdomain region of NS5 (residues 369-405). In this study, it is shown by using the yeast two-hybrid system that the C-terminal region of NS3 (residues 303-618) interacts with the N-terminal region of NS5 (residues 320-368).