Long-term maternal effect on offspring immune response in song sparrows Melospiza melodia

Knowledge of the causes of variation in host immunity to parasitic infection and the time-scales over which variation persists, is integral to predicting the evolutionary and epidemiological consequences of host-parasite interactions. It is clear that offspring immunity can be influenced by parental immune experience, for example, reflecting transfer of antibodies from mothers to young offspring. However, it is less clear whether such parental effects persist or have functional consequences over longer time-scales, linking a parent's previous immune experience to future immune responsiveness in fully grown offspring. We used free-living song sparrows (Melospiza melodia) to quantify long-term effects of parental immune experience on offspring immune response. We experimentally vaccinated parents with a novel antigen and tested whether parental vaccination influenced the humoral antibody response mounted by fully grown offspring hatched the following year. Parental vaccination did not influence offspring baseline antibody titres. However, offspring of vaccinated mothers mounted substantially stronger antibody responses than offspring of unvaccinated mothers. Antibody responses did not differ between offspring of vaccinated and unvaccinated fathers. These data demonstrate substantial long-term effects of maternal immune experience on the humoral immune response of fully grown offspring in free-living birds.     

PCR-RFLP based diagnostic tests for Moxostoma Species in Ontario

Six Moxostoma species are found in Ontario, including two federally listed species. Knowledge of their distribution and status has been limited by incorrect field identifications, collections that report Moxosotoma or sucker species, and new site records without voucher specimens. To develop species diagnostic genetic markers, we amplified and sequenced two mitochondrial genes (ATPase subunits 6 and 8). Species-specific sequence differences were easily identified (of 830 analyzed bases, 132 substitutions were phylogenetically informative). Based on sequence differences, four restriction enzymes were identified and tested for their reliability as species diagnostic tools. Restriction digests of previously sequenced samples matched predicted species-specific patterns. Overall, 90% of samples digested matched. Disagreement between 20% of samples provided by various government agencies and species-specific digest patterns indicate a need for greater care during field identifications.     

Slow translocon gating causes cytosolic exposure of transmembrane and lumenal domains during membrane protein integration

Integral membrane proteins are cotranslationally inserted into the endoplasmic reticulum via the protein translocation channel, or translocon, which mediates the transport of lumenal domains, retention of cytosolic domains and integration of transmembrane spans into the phospholipid bilayer. Upon translocon binding, transmembrane spans interact with a lateral gate, which regulates access to membrane phospholipids, and a lumenal gate, which controls the translocation of soluble domains. We analyzed the in vivo kinetics of integration of model membrane proteins in Saccharomyces cerevisiae using ubiquitin translocation assay reporters. Our findings indicate that the conformational changes in the translocon that permit opening of the lumenal and lateral channel gates occur less rapidly than elongation of the nascent polypeptide. Transmembrane spans and lumenal domains are therefore exposed to the cytosol during integration of a polytopic membrane protein, which may pose a challenge to the fidelity of membrane protein integration.     

Functional genomics of the yeast DNA-damage response

High-throughput approaches are beginning to have an impact on many areas of yeast biology. Two recent studies, using different experimental platforms, provide insight into new pathways involved in the response of yeast to DNA damage.     

The impact of intragenic recombination on phylogenetic reconstruction at the sectional level in Eucalyptus when using a single copy nuclear gene (cinnamoyl CoA reductase)

Low copy number nuclear genes have been found to be useful for phylogenetic reconstruction at different taxonomic levels. This study investigated the utility of a single copy gene, cinnamoyl CoA reductase (CCR), for resolving phylogenetic relationships at the sectional level within Eucalyptus. The monophyly of sections Exsertaria and Latoangulatae was explored, using section Maidenaria as an outgroup, and the impact of intragenic recombination on phylogenetic reconstruction examined. Phylogenetic analysis did not resolve monophyletic groups. Latoangulatae and Maidenaria were polyphyletic or paraphyletic. Exsertaria species formed a clade but included a single Latoangulatae species (E. major). Recombination analysis identified two intragenic recombination events that involved species from different sections, which have probably been facilitated by inter-sectional hybridisation. One of the events most likely occurred prior to speciation, with several Latoangulatae species having the recombinant allele. The other event may have occurred after speciation, since only one of two E. globulus samples possessed the recombinant allele. This is the first detailed report of intragenic recombination in both CCR and Eucalyptus, and between species of different sections of a plant genus. The occurrence of intragenic recombination may explain the anomalous positions of some species within the phylogenetic tree, and indicates that phylogenetic analysis of Eucalyptus using nuclear genes will be problematic unless recombination is taken into account.     

The MicroArray Quality Control (MAQC) project shows inter- and intraplatform reproducibility of gene expression measurements

Over the last decade, the introduction of microarray technology has had a profound impact on gene expression research. The publication of studies with dissimilar or altogether contradictory results, obtained using different microarray platforms to analyze identical RNA samples, has raised concerns about the reliability of this technology. The MicroArray Quality Control (MAQC) project was initiated to address these concerns, as well as other performance and data analysis issues. Expression data on four titration pools from two distinct reference RNA samples were generated at multiple test sites using a variety of microarray-based and alternative technology platforms. Here we describe the experimental design and probe mapping efforts behind the MAQC project. We show intraplatform consistency across test sites as well as a high level of interplatform concordance in terms of genes identified as differentially expressed. This study provides a resource that represents an important first step toward establishing a framework for the use of microarrays in clinical and regulatory settings.     

Clinical study comparing probiotic Lactobacillus GR-1 and RC-14 with metronidazole vaginal gel to treat symptomatic bacterial vaginosis

Bacterial vaginosis (BV) is particularly common in black women, and in Nigeria it is often caused by Mycoplasma, as well as Atopobium, Prevotella and Gardnerella sp. Antimicrobial metronidazole oral therapy is poorly effective in eradicating the condition and restoring the Lactobacillus microbiota in the vagina. In this study, 40 women diagnosed with BV by discharge, fishy odor, sialidase positive test and Nugent Gram stain scoring, were randomized to receive either two dried capsules containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 each night for 5 days, or 0.75% metronidazole gel, applied vaginally twice a day (in the morning and evening). Follow-up at day 6, 15 and 30 showed cure of BV in significantly more probiotic treated subjects (16, 17 and 18/20, respectively) compared to metronidazole treatment (9, 9 and 11/20: P=0.016 at day 6, P=0.002 at day 15 and P=0.056 at day 30). This is the first report of an effective (90%) cure of BV using probiotic lactobacilli. Given the correlation between BV and HIV, and the high risk of the latter in Nigeria, intravaginal use of lactobacilli could provide women with a self-use therapy, similar to over-the-counter anti-yeast medication, for treatment of urogenital infections.