Molecular evolution of the three short PGRPs of the malaria vectors <Emphasis Type="Italic">An</Emphasis>opheles <Emphasis Type="Italic">gambiae</Emphasis> and <Emphasis Type="Italic">Anopheles arabiensis</Emphasis>in East Africa

Background  

Immune responses to parasites, which start with pathogen recognition, play a decisive role in the control of the infection in mosquitoes. Peptidoglycan recognition proteins (PGRPs) are an important family of pattern recognition receptors that are involved in the activation of these immune reactions. Pathogen pressure can exert adaptive changes in host genes that are crucial components of the vector's defence. The aim of this study was to determine the molecular evolution of the three short PGRPs (PGRP-S1, PGRP-S2 and PGRP-S3) in the two main African malaria vectors - Anopheles gambiae and Anopheles arabiensis.     

The <Emphasis Type="Italic">MB2</Emphasis> gene family of <Emphasis Type="Italic">Plasmodium</Emphasis> species has a unique combination of S1 and GTP-binding domains

Background  

Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing.     

Possible use of <Emphasis Type="Italic">ail</Emphasis> and <Emphasis Type="Italic">foxA</Emphasis> polymorphisms for detecting pathogenic <Emphasis Type="Italic">Yersinia enterocolitica</Emphasis>

Background  

Yersinia enterocolitica is an enteric pathogen that invades the intestinal mucosa and proliferates within the lymphoid follicles (Peyer's patches). The attachment invasion locus (ail) mediates invasion by Y. enterocolitica and confers an invasive phenotype upon non-invasive E. coli; ail is the primary virulence factor of Y. enterocolitica. The ferrioxamine receptor (foxA) located on the Y. enterocolitica chromosome, together with its transport protein, transports a siderophore specific for ferric ion. Currently, ail is the primary target gene for nucleic acid detection of pathogenic Y. enterocolitica.     

<Emphasis Type="Italic">Erwinia carotovora</Emphasis> elicitors and <Emphasis Type="Italic">Botrytis cinerea</Emphasis> activate defense responses in <Emphasis Type="Italic">Physcomitrella patens</Emphasis>

Background  

Vascular plants respond to pathogens by activating a diverse array of defense mechanisms. Studies with these plants have provided a wealth of information on pathogen recognition, signal transduction and the activation of defense responses. However, very little is known about the infection and defense responses of the bryophyte, Physcomitrella patens, to well-studied phytopathogens. The purpose of this study was to determine: i) whether two representative broad host range pathogens, Erwinia carotovora ssp. carotovora (E.c. carotovora) and Botrytis cinerea (B. cinerea), could infect Physcomitrella, and ii) whether B. cinerea, elicitors of a harpin (HrpN) producing E.c. carotovora strain (SCC1) or a HrpN-negative strain (SCC3193), could cause disease symptoms and induce defense responses in Physcomitrella.     

Common genomic features of <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> subsp. <Emphasis Type="Italic">doylei</Emphasis> strains distinguish them from <Emphasis Type="Italic">C. jejuni</Emphasis> subsp. <Emphasis Type="Italic">jejuni</Emphasis>

Background  

Campylobacter jejuni has been divided into two subspecies: C. jejuni subsp. jejuni (Cjj) and C. jejuni subsp. doylei (Cjd). Nearly all of the C. jejuni strains isolated are Cjj; nevertheless, although Cjd strains are isolated infrequently, they differ from Cjj in two key aspects: they are obtained primarily from human clinical samples and are associated often with bacteremia, in addition to gastroenteritis. In this study, we utilized multilocus sequence typing (MLST) and a DNA microarray-based comparative genomic indexing (CGI) approach to examine the genomic diversity and gene content of Cjd strains.     

Evolution of <Emphasis Type="Italic">mal</Emphasis> ABC transporter operons in the <Emphasis Type="Italic">Thermococcales</Emphasis> and <Emphasis Type="Italic">Thermotogales</Emphasis>

Background  

The mal genes that encode maltose transporters have undergone extensive lateral transfer among ancestors of the archaea Thermococcus litoralis and Pyrococcus furiosus. Bacterial hyperthermophiles of the order Thermotogales live among these archaea and so may have shared in these transfers. The genome sequence of Thermotoga maritima bears evidence of extensive acquisition of archaeal genes, so its ancestors clearly had the capacity to do so. We examined deep phylogenetic relationships among the mal genes of these hyperthermophiles and their close relatives to look for evidence of shared ancestry.     

Expression profiling and integrative analysis of the <Emphasis Type="Italic">CESA</Emphasis>/<Emphasis Type="Italic">CSL</Emphasis> superfamily in rice

Background  

The cellulose synthase and cellulose synthase-like gene superfamily (CESA/CSL) is proposed to encode enzymes for cellulose and non-cellulosic matrix polysaccharide synthesis in plants. Although the rice (Oryza sativa L.) genome has been sequenced for a few years, the global expression profiling patterns and functions of the OsCESA/CSL superfamily remain largely unknown.     

<Emphasis Type="Italic">R-spondin1</Emphasis> and <Emphasis Type="Italic">FOXL2</Emphasis>act into two distinct cellular types during goat ovarian differentiation

Background  

Up to now, two loci have been involved in XX sex-reversal in mammals following loss-of-function mutations, PIS (Polled Intersex Syndrome) in goats and R-spondin1 (RSPO1) in humans. Here, we analyze the possible interaction between these two factors during goat gonad development. Furthermore, since functional redundancy between different R-spondins may influence gonad development, we also studied the expression patterns of RSPO2, 3 and 4.     

Attenuation of fibrosis <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> with <Emphasis Type="Italic">SPARC</Emphasis> siRNA

Introduction  

SPARC is a matricellular protein, which, along with other extracellular matrix components including collagens, is commonly over-expressed in fibrotic diseases. The purpose of this study was to examine whether inhibition of SPARC can regulate collagen expression in vitro and in vivo, and subsequently attenuate fibrotic stimulation by bleomycin in mouse skin and lungs.     

The molecular evolution of <Emphasis Type="Italic">PL10</Emphasis> homologs

Background  

PL10 homologs exist in a wide range of eukaryotes from yeast, plants to animals. They share a DEAD motif and belong to the DEAD-box polypeptide 3 (DDX3) subfamily with a major role in RNA metabolism. The lineage-specific expression patterns and various genomic structures and locations of PL10 homologs indicate these homologs have an interesting evolutionary history.     

Recombinant production of <Emphasis Type="Italic">Streptococcus equisimilis</Emphasis> streptokinase by <Emphasis Type="Italic">Streptomyces lividans</Emphasis>

Background  

Streptokinase (SK) is a potent plasminogen activator with widespread clinical use as a thrombolytic agent. It is naturally secreted by several strains of beta-haemolytic streptococci. The low yields obtained in SK production, lack of developed gene transfer methodology and the pathogenesis of its natural host have been the principal reasons to search for a recombinant source for this important therapeutic protein. We report here the expression and secretion of SK by the Gram-positive bacterium Streptomyces lividans. The structural gene encoding SK was fused to the Streptomyces venezuelae CBS762.70 subtilisin inhibitor (vsi) signal sequence or to the Streptomyces lividans xylanase C (xlnC) signal sequence. The native Vsi protein is translocated via the Sec pathway while the native XlnC protein uses the twin-arginine translocation (Tat) pathway.     

Cloning and characterization of cDNAs encoding putative CTCFs in the mosquitoes, <Emphasis Type="Italic">Aedes aegypti</Emphasis> and <Emphasis Type="Italic">Anopheles gambiae</Emphasis>

Background  

One of the many ascribed functions of CCCTC-binding factor (CTCF) in vertebrates is insulation of genes via enhancer-blocking. Insulation allows genes to be shielded from "cross-talk" with neighboring regulatory elements. As such, endogenous insulator sequences would be valuable elements to enable stable transgene expression. Recently, CTCF joined Su(Hw), Zw5, BEAF32 and GAGA factor as a protein associated with insulator activity in the fruitfly, Drosophila melanogaster. To date, no known insulators have been described in mosquitoes.     

Polymorphism at the apical membrane antigen 1 locus reflects the world population history of <Emphasis Type="Italic">Plasmodium vivax</Emphasis>

Background  

In malaria parasites (genus Plasmodium), ama-1 is a highly polymorphic locus encoding the Apical Membrane Protein-1, and there is evidence that the polymorphism at this locus is selectively maintained. We tested the hypothesis that polymorphism at the ama-1 locus reflects population history in Plasmodium vivax, which is believed to have originated in Southeast Asia and is widely geographically distributed. In particular, we tested for a signature of the introduction of P. vivax into the New World at the time of the European conquest and African slave trade and subsequent population expansion.     

Expression and functional analysis of <Emphasis Type="Italic">TaASY1</Emphasis> during meiosis of bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>)

Background  

Pairing and synapsis of homologous chromosomes is required for normal chromosome segregation and the exchange of genetic material via recombination during meiosis. Synapsis is complete at pachytene following the formation of a tri-partite proteinaceous structure known as the synaptonemal complex (SC). In yeast, HOP1 is essential for formation of the SC, and localises along chromosome axes during prophase I. Homologues in Arabidopsis (AtASY1), Brassica (BoASY1) and rice (OsPAIR2) have been isolated through analysis of mutants that display decreased fertility due to severely reduced synapsis of homologous chromosomes. Analysis of these genes has indicated that they play a similar role to HOP1 in pairing and formation of the SC through localisation to axial/lateral elements of the SC.     

Independent Origins of New Sex-Linked Chromosomes in the <Emphasis Type="Italic">melanica</Emphasis> and <Emphasis Type="Italic">robusta</Emphasis> Species Groups of <Emphasis Type="Italic">Drosophila</Emphasis>

Background  

Recent translocations of autosomal regions to the sex chromosomes represent important systems for identifying the evolutionary forces affecting convergent patterns of sex-chromosome heteromorphism. Additions to the sex chromosomes have been reported in the melanica and robusta species groups, two sister clades of Drosophila. The close relationship between these two species groups and the similarity of their rearranged karyotypes motivates this test of alternative hypotheses; the rearranged sex chromosomes in both groups are derived through a common origin, or the rearrangements are derived through at least two independent origins. Here we examine chromosomal arrangement in representatives of the melanica and the robusta species groups and test these alternative hypotheses using a phylogenetic approach.     

Genetic fine-mapping of <Emphasis Type="Italic">DIPLOSPOROUS</Emphasis> in <Emphasis Type="Italic">Taraxacum</Emphasis> (dandelion; Asteraceae) indicates a duplicated <Emphasis Type="Italic">DIP</Emphasis>-gene

Background  

DIPLOSPOROUS (DIP) is the locus for diplospory in Taraxacum, associated to unreduced female gamete formation in apomicts. Apomicts reproduce clonally through seeds, including apomeiosis, parthenogenesis, and autonomous or pseudogamous endosperm formation. In Taraxacum, diplospory results in first division restitution (FDR) nuclei, and inherits as a dominant, monogenic trait, independent from the other apomixis elements. A preliminary genetic linkage map indicated that the DIP-locus lacks suppression of recombination, which is unique among all other map-based cloning efforts of apomeiosis to date. FDR as well as apomixis as a whole are of interest in plant breeding, allowing for polyploidization and fixation of hybrid vigor, respectively. No dominant FDR or apomixis genes have yet been isolated. Here, we zoom-in to the DIP-locus by largely extending our initial mapping population, and by analyzing (local) suppression of recombination and allele sequence divergence (ASD).     

Evolution of the <Emphasis Type="Italic">DAZ</Emphasis> gene and the <Emphasis Type="Italic">AZFc</Emphasis> region on primate Y chromosomes

Background  

The Azoospermia Factor c (AZFc) region of the human Y chromosome is a unique product of segmental duplication. It consists almost entirely of very long amplicons, represented by different colors, and is frequently deleted in subfertile men. Most of the AZFc amplicons have high sequence similarity with autosomal segments, indicating recent duplication and transposition to the Y chromosome. The Deleted in Azoospermia (DAZ) gene within the red-amplicon arose from an ancestral autosomal DAZ-like (DAZL) gene. It varies significantly between different men regarding to its copy number and the numbers of RNA recognition motif and DAZ repeat it encodes. We used Southern analyses to study the evolution of DAZ and AZFc amplicons on the Y chromosomes of primates.     

The RNA interference pathway affects midgut infection- and escape barriers for Sindbis virus in <Emphasis Type="Italic">Aedes aegypti</Emphasis>

Background  

The RNA interference (RNAi) pathway acts as an innate antiviral immune response in Aedes aegypti, modulating arbovirus infection of mosquitoes. Sindbis virus (SINV; family: Togaviridae, genus: Alphavirus) is an arbovirus that infects Ae. aegypti in the laboratory. SINV strain TR339 encounters a midgut escape barrier (MEB) during infection of Ae. aegypti. The nature of this barrier is not well understood. To investigate the role of the midgut as the central organ determining vector competence for arboviruses, we generated transgenic mosquitoes in which the RNAi pathway was impaired in midgut tissue of bloodfed females. We used these mosquitoes to reveal effects of RNAi impairment in the midgut on SINV replication, midgut infection and dissemination efficiencies, and mosquito longevity.