Environmental factors influence the local establishment of in mosquitoes in two small communities in central Vietnam.

The Mel strain of has been successfully introduced into mosquitoes and subsequently shown to reduce transmission of dengue and other pathogens, under both laboratory and field conditions. Here we describe the entomological outcomes of Mel mosquito releases in two small communities in Nha Trang City in central Vietnam. The Mel strain of was backcrossed into local genotype and mosquito releases were undertaken by community members or by staff.

Wolbachia-mediated virus blocking in mosquito cells is dependent on XRN1-mediated viral RNA degradation and influenced by viral replication rate.

Wolbachia is currently being developed as a novel tool to block the transmission of dengue viruses (DENV) by Aedes aegypti. A number of mechanisms have been proposed to explain the DENV-blocking phenotype in mosquitoes, including competition for fatty acids like cholesterol, manipulation of host miRNAs and upregulation of innate immune pathways in the mosquito. We examined the various stages in the DENV infection process to better understand the mechanism of Wolbachia-mediated virus blocking (WMVB).

Wolbachia infection alters the relative abundance of resident bacteria in adult Aedes aegypti mosquitoes, but not larvae.

Insect-symbiont interactions are known to play key roles in host functions and fitness. The common insect endosymbiont Wolbachia can reduce the ability of several human pathogens, including arboviruses and the malaria parasite, to replicate in insect hosts. Wolbachia does not naturally infect Aedes aegypti, the primary vector of dengue virus, but transinfected Ae.

Gut microbiota in Drosophila melanogaster interacts with Wolbachia but does not contribute to Wolbachia-mediated antiviral protection.

Animals experience near constant infection with microorganisms. A significant proportion of these microbiota reside in the alimentary tract. There is a growing appreciation for the roles gut microbiota play in host biology.

A Native Wolbachia Endosymbiont Does Not Limit Dengue Virus Infection in the Mosquito Aedes notoscriptus (Diptera: Culicidae).

The endosymbiotic bacterium Wolbachia pipientis infects many species of insects and has been transinfected into the mosquito Aedes aegypti (L.), the primary vector of dengue virus (DENV). Recently, it has been shown that Wolbachia blocks the replication and transmission of RNA viruses, such as DENV, in a number of mosquito species including Ae.

Discovery of putative small non-coding RNAs from the obligate intracellular bacterium Wolbachia pipientis.

Wolbachia pipientis is an endosymbiotic bacterium that induces a wide range of effects in its insect hosts, including manipulation of reproduction and protection against pathogens. Little is known of the molecular mechanisms underlying the insect-Wolbachia interaction, though it is likely to be mediated via the secretion of proteins or other factors. There is an increasing amount of evidence that bacteria regulate many cellular processes, including secretion of virulence factors, using small non-coding RNAs (sRNAs), but sRNAs have not previously been described from Wolbachia.

A distinct and divergent lineage of genomic island-associated Type IV Secretion Systems in Legionella.

Legionella encodes multiple classes of Type IV Secretion Systems (T4SSs), including the Dot/Icm protein secretion system that is essential for intracellular multiplication in amoebal and human hosts. Other T4SSs not essential for virulence are thought to facilitate the acquisition of niche-specific adaptation genes including the numerous effector genes that are a hallmark of this genus. Previously, we identified two novel gene clusters in the draft genome of Legionella pneumophila strain 130b that encode homologues of a subtype of T4SS, the genomic island-associated T4SS (GI-T4SS), usually associated with integrative and conjugative elements (ICE).

Genomic evolution of the pathogenic Wolbachia strain, wMelPop.

Most strains of the widespread endosymbiotic bacterium Wolbachia pipientis are benign or behave as reproductive parasites. The pathogenic strain wMelPop is a striking exception, however: it overreplicates in its insect hosts and causes severe life shortening. The mechanism of this pathogenesis is currently unknown.

Wolbachia-associated bacterial protection in the mosquito Aedes aegypti.

Background: Wolbachia infections confer protection for their insect hosts against a range of pathogens including bacteria, viruses, nematodes and the malaria parasite. A single mechanism that might explain this broad-based pathogen protection is immune priming, in which the presence of the symbiont upregulates the basal immune response, preparing the insect to defend against subsequent pathogen infection. A study that compared natural Wolbachia infections in Drosophila melanogaster with the mosquito vector Aedes aegypti artificially transinfected with the same strains has suggested that innate immune priming may only occur in recent host-Wolbachia associations.

Infection with a Virulent Strain of Wolbachia Disrupts Genome Wide-Patterns of Cytosine Methylation in the Mosquito Aedes aegypti.

Background: Cytosine methylation is one of several reversible epigenetic modifications of DNA that allow a greater flexibility in the relationship between genotype and phenotype. Methylation in the simplest models dampens gene expression by modifying regions of DNA critical for transcription factor binding. The capacity to methylate DNA is variable in the insects due to diverse histories of gene loss and duplication of DNA methylases.

Draft genome sequence of the male-killing Wolbachia strain wBol1 reveals recent horizontal gene transfers from diverse sources.

Background: The endosymbiont Wolbachia pipientis causes diverse and sometimes dramatic phenotypes in its invertebrate hosts. Four Wolbachia strains sequenced to date indicate that the constitution of the genome is dynamic, but these strains are quite divergent and do not allow resolution of genome diversification over shorter time periods. We have sequenced the genome of the strain wBol1-b, found in the butterfly Hypolimnas bolina, which kills the male offspring of infected hosts during embyronic development and is closely related to the non-male-killing strain wPip from Culex pipiens.

Influence of the virus LbFV and of Wolbachia in a host-parasitoid interaction.

Symbionts are widespread and might have a substantial effect on the outcome of interactions between species, such as in host-parasitoid systems. Here, we studied the effects of symbionts on the outcome of host-parasitoid interactions in a four-partner system, consisting of the parasitoid wasp Leptopilina boulardi, its two hosts Drosophila melanogaster and D. simulans, the wasp virus LbFV, and the endosymbiotic bacterium Wolbachia.

The relative importance of innate immune priming in Wolbachia-mediated dengue interference.

The non-virulent Wolbachia strain wMel and the life-shortening strain wMelPop-CLA, both originally from Drosophila melanogaster, have been stably introduced into the mosquito vector of dengue fever, Aedes aegypti. Each of these Wolbachia strains interferes with viral pathogenicity and/or dissemination in both their natural Drosophila host and in their new mosquito host, and it has been suggested that this virus interference may be due to host immune priming by Wolbachia. In order to identify aspects of the mosquito immune response that might underpin virus interference, we used whole-genome microarrays to analyse the transcriptional response of A.

Tandem repeat markers as novel diagnostic tools for high resolution fingerprinting of Wolbachia.

Background: Strains of the endosymbiotic bacterium Wolbachia pipientis are extremely diverse both genotypically and in terms of their induced phenotypes in invertebrate hosts. Despite extensive molecular characterisation of Wolbachia diversity, little is known about the actual genomic diversity within or between closely related strains that group tightly on the basis of existing gene marker systems, including Multiple Locus Sequence Typing (MLST). There is an urgent need for higher resolution fingerprinting markers of Wolbachia for studies of population genetics, horizontal transmission and experimental evolution.

Quantifying the variation in the effective population size within a genome.

The effective population size (N(e)) is one of the most fundamental parameters in population genetics. It is thought to vary across the genome as a consequence of differences in the rate of recombination and the density of selected sites due to the processes of genetic hitchhiking and background selection. Although it is known that there is intragenomic variation in the effective population size in some species, it is not known whether this is widespread or how much variation in the effective population size there is.

Parallel evolution of the make-accumulate-consume strategy in Saccharomyces and Dekkera yeasts.

Saccharomyces yeasts degrade sugars to two-carbon components, in particular ethanol, even in the presence of excess oxygen. This characteristic is called the Crabtree effect and is the background for the 'make-accumulate-consume' life strategy, which in natural habitats helps Saccharomyces yeasts to out-compete other microorganisms. A global promoter rewiring in the Saccharomyces cerevisiae lineage, which occurred around 100 mya, was one of the main molecular events providing the background for evolution of this strategy.

A simple protocol to obtain highly pure Wolbachia endosymbiont DNA for genome sequencing.

Most genome sequencing projects using intracellular bacteria face difficulties in obtaining sufficient bacterial DNA free of host contamination. We have developed a simple and rapid protocol to isolate endosymbiont DNA virtually free from fly and mosquito host DNA. We purified DNA from six Wolbachia strains in preparation for genome sequencing using this method, and achieved up to 97% pure Wolbachia sequence, even after using frozen insects.

Massively parallel sequencing and analysis of expressed sequence tags in a successful invasive plant.

Background: Invasive species pose a significant threat to global economies, agriculture and biodiversity. Despite progress towards understanding the ecological factors associated with plant invasions, limited genomic resources have made it difficult to elucidate the evolutionary and genetic factors responsible for invasiveness. This study presents the first expressed sequence tag (EST) collection for Senecio madagascariensis, a globally invasive plant species.

Increased locomotor activity and metabolism of Aedes aegypti infected with a life-shortening strain of Wolbachia pipientis.

A virulent strain of the obligate intracellular bacterium Wolbachia pipientis that shortens insect lifespan has recently been transinfected into the primary mosquito vector of dengue virus, Aedes aegypti L. The microbe's ability to shorten lifespan and spread through host populations under the action of cytoplasmic incompatibility means it has the potential to be used as a biocontrol agent to reduce dengue virus transmission. Wolbachia is present in many host tissues and may have local effects on diverse biological processes.

Effective population size and the rate and pattern of nucleotide substitutions.

Both the overall rate of nucleotide substitution and the relative proportions of synonymous and non-synonymous substitutions are predicted to vary between species that differ in effective population size (N(e)). Our understanding of the genetic processes underlying these lineage-specific differences in molecular evolution is still developing. Empirical analyses indicate that variation in substitution rates and patterns caused by differences in N(e) is often substantial, however, and must be accounted for in analyses of molecular evolution.

An ancient horizontal gene transfer between mosquito and the endosymbiotic bacterium Wolbachia pipientis.

The extent and biological relevance of horizontal gene transfer (HGT) in eukaryotic evolution remain highly controversial. Recent studies have demonstrated frequent and large-scale HGT from endosymbiotic bacteria to their hosts, but the great majority of these transferred genes rapidly become nonfunctional in the recipient genome. Here, we investigate an ancient HGT between a host metazoan and an endosymbiotic bacterium, Wolbachia pipientis.

Complex evolution of the DAL5 transporter family.

Background: Genes continuously duplicate and the duplicated copies remain in the genome or get deleted. The DAL5 subfamily of transmembrane transporter genes has eight known members in S. cerevisiae.

Independent sorting-out of thousands of duplicated gene pairs in two yeast species descended from a whole-genome duplication.

Among yeasts that underwent whole-genome duplication (WGD), Kluyveromyces polysporus represents the lineage most distant from Saccharomyces cerevisiae. By sequencing the K. polysporus genome and comparing it with the S.

Genome survey sequencing of the wine spoilage yeast Dekkera (Brettanomyces) bruxellensis.

The hemiascomycete yeast Dekkera bruxellensis, also known as Brettanomyces bruxellensis, is a major cause of wine spoilage worldwide. Wines infected with D. bruxellensis develop distinctive, unpleasant aromas due to volatile phenols produced by this species, which is highly ethanol tolerant and facultatively anaerobic.

There is no universal molecular clock for invertebrates, but rate variation does not scale with body size.

The existence of a universal molecular clock has been called into question by observations that substitution rates vary widely between lineages. However, increasing empirical evidence for the systematic effects of different life history traits on the rate of molecular evolution has raised hopes that rate variation may be predictable, potentially allowing the "correction" of the molecular clock. One such example is the body size trend observed in vertebrates; smaller species tend to have faster rates of molecular evolution.