Identification of Lactobacillus species using tDNA-PCR

tDNA intergenic spacer PCR (tDNA-PCR) using consensus primers complementary to the conserved edges of the tRNA genes can amplify the intergenic spacers. Separation of the PCR products with capillary electrophoresis enables discrimination between fragments differing only one basepair in length. This method was applied to a collection of 82 Lactobacillus strains belonging to 37 species in order to evaluate the discriminatory power of this technique within this genus. Twenty-one species could be distinguished to species level on the basis of a unique tDNA fingerprint pattern. The other species grouped by two (e.g. L. fermentum and L. cellobiosus) or three (L. acidophilus, L. gallinarum and L. helveticus). Inclusion of the resulting fingerprints in a numerical database containing fingerprints of numerous other Gram-positive and Gram-negative species makes the identification of unknown strains possible.     

The monosaccharide binding site of lentil lectin: an X-ray and molecular modelling study

The X-ray crystal structure of lentil lectin in complex with -d-glucopyranose has been determined by molecular replacement and refined to anR-value of 0.20 at 3.0 Å resolution. The glucose interacts with the protein in a manner similar to that found in the mannose complexes of concanavalin A, pea lectin and isolectin I fromLathyrus ochrus. The complex is stabilized by a network of hydrogen bonds involving the carbohydrate oxygens O6, O4, O3 and O5. In addition, the -d-glucopyranose residue makes van der Waals contacts with the protein, involving the phenyl ring of Phe123. The overall structure of lentil lectin, at this resolution, does not differ significantly from the highly refined structures of the uncomplexed lectin.Molecular docking studies were performed with mannose and its 2-O and 3-O-m-nitro-benzyl derivatives to explain their high affinity binding. The interactions of the modelled mannose with lentil lectin agree well with those observed experimentally for the protein-carbohydrate complex. The highly flexible Me-2-O-(m-nitro-benzyl)--d-mannopyranoside and Me-3-O-(m-nitro-benzyl)--d-mannopyranoside become conformationally restricted upon binding to lentil lectin. For best orientations of the two substrates in the combining site, the loss of entropy is accompanied by the formation of a strong hydrogen bond between the nitro group and one amino acid, Gly97 and Asn125, respectively, along with the establishment of van der Waals interactions between the benzyl group and the aromatic amino acids Tyr100 and Trp128.RL and FC are joint first authors.     

Ecological specialization of mixotrophic plankton in a mixed water column

In recent years, the population dynamics of plankton in light- or nutrient-limited environments have been studied extensively. Their evolutionary dynamics, however, have received much less attention. Here, we used a modeling approach to study the evolutionary behavior of a population of plankton living in a mixed water column. Initially, the organisms are mixotrophic and thus have both autotrophic and heterotrophic abilities. Through evolution of their trophic preferences, however, they can specialize into separate autotrophs and heterotrophs. It was found that the light intensity gradient enables evolutionary branching and thus may result in the ecological specialization of the mixotrophs. By affecting the gradient, other environmental properties also acquire influence on this evolutionary process. Intermediate mixing intensities, large mixing depths, and high nutrient densities were found to facilitate evolutionary branching and thus specialization. Later results may explain why mixotrophs are often more dominant in oligotrophic systems while specialist strategies are associated with eutrophic systems.     

Jagged1 signals in the postnatal subventricular zone are required for neural stem cell self-renewal

Neural stem cells (NSCs) in the postnatal mammalian brain self-renew and are a source of neurons and glia. To date, little is known about the molecular and cellular mechanisms regulating the maintenance and differentiation of these multipotent progenitors. We show that Jagged1 is required by mitotic cells in the subventricular zone (SVZ) and stimulates self-renewal of multipotent epidermal growth factor-dependent NSCs. Jagged1-expressing cells line the adult SVZ and are juxtaposed to Notch1-expressing cells, some of which are putative NSCs. In vitro, endogenous Jagged1 acts through Notch1 to promote NSC maintenance and multipotency. In vivo, reducing Jagged1/Notch1 signaling decreases the number of proliferating cells in the SVZ. In addition, soluble Jagged1 promotes self-renewal and neurogenic potential of multipotent neural progenitors in vitro. Our findings suggest a central role for Jagged1 in the NSC niche in the SVZ for maintaining a population of NSCs in the postnatal brain.     

A comparative evaluation of phenotypic and molecular methods in the identification of members of the Staphylococcus sciuri group

Members of the Staphylococcus sciuri group (S. sciuri, S. lentus, and S. vitulinus) are coagulase-negative, novobiocin-resistant staphylococci that could be distinguished from other staphylococci on the basis of positive oxidase activity. In the present study, a scheme based on conventional methods and utilization of various carbohydrates was evaluated for the identification of oxidase-positive staphylococci, and validated using two molecular techniques. Of the 173 oxidase-positive staphylococcal tested strains, 161 were identified as S. sciuri, 9 as S. lentus, 2 as S. vitulinus, and one as S. fleurettii by our scheme. The level of agreement with tRNA intergenic length polymorphism analysis (tDNA-PCR) was high (97.5-100% correlation). The accuracy and ease of use of this protocol suggest that it may be useful and valuable in microbiological laboratories for the identification of members of this group.     

Selection component analysis of natural polymorphisms using population samples including mother-offspring combinations, III

Population samples including mother-offspring combinations with three or more offspring provide complete information on the selection components in a monogamous organism with discrete generations. The theory for the analysis of a sample consisting of adult individuals including combinations of a mother and a number of her offspring is developed for a one-locus two-allele polymorphism, and extension of the analysis to more complex polymorphisms is discussed. The analysis is illustrated by data from a population of the amphipod Gammarus oceanicus.     

Use of Menopausal Hormone Therapy and Bioidentical Hormone Therapy in Australian Women 50 to 69 Years of Age: Results from a National,Cross-Sectional Study

Menopausal Hormone Therapy (MHT) use in Australia fell by 55% from 2001 to 2005, following the release of large-scale findings on its risks and benefits. Comprehensive national data, including information on overall prevalence of MHT use as well as information on duration of use in Australia have not been reported since the 2004–5 National Health Survey, when 11% of women aged 45+ years were estimated to be current MHT users. No national data are available on prevalence of use of “bioidentical” hormone therapy (BHT). The objective of this study was to determine recent prevalence of MHT and BHT use. A cross-sectional, national, age-stratified, population survey was conducted in 2013. Eligible women, aged 50–69 years, resident in Australia were randomly sampled in 5-year age groups from the Medicare enrolment database (Australia’s universal health scheme). The response rate was 22% based on return of completed questionnaires, and analyses were restricted to 4,389 women within the specified age range. The estimated population-weighted prevalence of current use of MHT was 13% (95%CI 12–14), which was broadly similar to the previously reported national figures in 2004–5, suggesting that the use of MHT in Australia has largely stabilised over the past decade. A total of 39% and 20% of current-users with an intact uterus reported use of oestrogen-progestagen MHT and oestrogen-only MHT, respectively, whereas 77% of hysterectomised current-users used oestrogen-only MHT. Almost three-quarters of current-users [population-weighted prevalence 9% (95%CI 8–10)] had used MHT for ≥5 years. In regard to BHT, estimated population-weighted prevalence of ever use was 6% (95%CI 6–7) and 2% (95%CI 2–3) for current use. The population-weighted prevalence of MHT and BHT combined, in current users in their fifties and sixties was 15% (95%CI 14–16). These data provide a recent national “snapshot” of Australian women’s use of both conventional MHT and of BHT.