Diversity of Chironomidae (Diptera) along a salinity gradient in lakes of the endorheic Great Lakes region of western Mongolia

Hydrobiologia - The Great Lakes region of western Mongolia includes a diversity of lake ecosystems, from alpine freshwater to lowland, saline lakes, which increasingly face environmental threats...     

Understanding the Complexity of Ambivalence Toward Pregnancy: Does It Predict Inconsistent Use of Contraception?

Ambivalence towards future pregnancy is common and may increase the risk of unprotected sex and unintended pregnancy. We propose that ambivalent attitudes toward pregnancy consist of subtypes that are differentially associated with contraceptive use. Using data from a nationally representative survey of unmarried young adults (N = 1,147), we constructed four categories of ambivalence based on attitudes toward a hypothetical pregnancy. Multivariate analyses examined characteristics of ambivalence and the association between ambivalence and contraceptive use. Approximately one third of sexually active unmarried young adults are ambivalent about pregnancy. Having positive ambivalence (important to avoid a pregnancy but would be happy if it occurred) is associated with age, gender, education, and Hispanic origin. Although ambivalence toward pregnancy is associated with lower contraceptive use, this is true only among women with negative ambivalence (not important to avoid a pregnancy but would be unhappy if a pregnancy occurred). Attitudes toward pregnancy are multifaceted, and a more nuanced understanding of women’s attitudes toward pregnancy can help target prevention programs and related policies for women at risk of unintended pregnancy.     

Development of a plant transformation selection system based on expression of genes encoding gentamicin acetyltransferases

The development of selectable markers for transformation has been a major factor in the successful genetic manipulation of plants. A new selectable marker system has been developed based on bacterial gentamicin-3-N-acetyltransferases [AAC(3)]. These enzymes inactivate aminoglycoside antibiotics by acetylation. Two examples of AAC(3) enzymes have been manipulated to be expressed in plants. Chimeric AAC(3)-III and AAC(3)-IV genes were assembled using the constitutively expressed cauliflower mosaic virus 35S promoter and the nopaline synthase 3′ nontranslated region. These chimeric genes were engineered into vectors for Agrobacterium-mediated plant transformation. Petunia hybrida and Arabidopsis thaliana tissue transformed with these vectors grew in the presence of normally lethal levels of gentamicin. The transformed nature of regenerated Arabidopsis plants was confirmed by DNA hybridization analysis and inheritance of the selectable phenotype in progeny. The chimeric AAC(3)-IV gene has also been used to select transformants in several additional plant species. These results show that the bacterial AAC(3) genes will serve as useful selectable markers in plant tissue culture.     

A Nonquiescent “Idling” Population State in Drug-Treated,BRAF-Mutated Melanoma

Targeted therapy is an effective standard of care in BRAF-mutated malignant melanoma. However, the duration of tumor remission varies unpredictably among patients, and relapse is almost inevitable. Here, we examine the responses of several BRAF-mutated melanoma cell lines (including isogenic subclones) to BRAF inhibitors. We observe complex response dynamics across cell lines, with short-term responses (<100 h) varying from cell line to cell line. In the long term, however, we observe equilibration of all drug-treated populations into a nonquiescent state characterized by a balanced rate of death and division, which we term the “idling” state, and to our knowledge, this state has not been previously reported. Using mathematical modeling, we propose that the observed population-level dynamics are the result of cells transitioning between basins of attraction within a drug-modified phenotypic landscape. Each basin is associated with a drug-induced proliferation rate, a recently introduced metric of an antiproliferative drug effect. The idling population state represents a new dynamic equilibrium in which cells are distributed across the landscape such that the population achieves zero net growth. By fitting our model to experimental drug-response data, we infer the phenotypic landscapes of all considered melanoma cell lines and provide a unifying view of how BRAF-mutated melanomas respond to BRAF inhibition. We hypothesize that the residual disease observed in patients after targeted therapy is composed of a significant number of idling cells. Thus, defining molecular determinants of the phenotypic landscape that idling populations occupy may lead to “targeted landscaping” therapies based on rational modification of the landscape to favor basins with greater drug susceptibility.     

Use of Conserved Randomly Amplified Polymorphic DNA (RAPD) Fragments and RAPD Pattern for Characterization of Lactobacillus fermentum in Ghanaian Fermented Maize Dough

The present work describes the use of randomly amplified polymorphic DNA (RAPD) for the characterization of 172 dominant Lactobacillus isolates from present and previous studies of Ghanaian maize fermentation. Heterofermentative lactobacilli dominate the fermentation flora, since approximately 85% of the isolates belong to this group. Cluster analysis of the RAPD profiles obtained showed the presence of two main clusters. Cluster 1 included Lactobacillus fermentum, whereas cluster 2 comprised the remaining Lactobacillus spp. The two distinct clusters emerged at the similarity level of <50%. All isolates in cluster 1 showed similarity in their RAPD profile to the reference strains of L. fermentum included in the study. These isolates, yielding two distinct bands of approximately 695 and 773 bp with the primers used, were divided into four subclusters, indicating that several strains are involved in the fermentation and remain dominant throughout the process. The two distinct RAPD fragments were cloned, sequenced, and used as probes in Southern hybridization experiments. With one exception, Lactobacillus reuteri LMG 13045, the probes hybridized only to fragments of different sizes in EcoRI-digested chromosomal DNA of L. fermentum strains, thus indicating the specificity of the probes and variation within the L. fermentum isolates.     

Screening of probiotic activities of forty-seven strains of Lactobacillus spp. by in vitro techniques and evaluation of the colonization ability of five selected strains in humans.

The probiotic potential of 47 selected strains of Lactobacillus spp. was investigated. The strains were examined for resistance to pH 2.5 and 0.3% oxgall, adhesion to Caco-2 cells, and antimicrobial activities against enteric pathogenic bacteria in model systems. From the results obtained in vitro, five strains, Lactobacillus rhamnosus 19070-2, L. reuteri DSM 12246, L. rhamnosus LGG, L. delbrueckii subsp. lactis CHCC 2329, and L. casei subsp. alactus CHCC 3137, were selected for in vivo studies. The daily consumption by 12 healthy volunteers of two doses of 10(10) freeze-dried bacteria of the selected strains for 18 days was followed by a washout period of 17 days. Fecal samples were taken at days 0 and 18 and during the washout period at days 5 and 11. Lactobacillus isolates were initially identified by API 50CHL and internal transcribed spacer PCR, and their identities were confirmed by restriction enzyme analysis in combination with pulsed-field gel electrophoresis. Among the tested strains, L. rhamnosus 19070-2, L. reuteri DSM 12246, and L. rhamnosus LGG were identified most frequently in fecal samples; they were found in 10, 8, and 7 of the 12 samples tested during the intervention period, respectively, whereas reisolations were less frequent in the washout period. The bacteria were reisolated in concentrations from 10(5) to 10(8) cells/g of feces. Survival and reisolation of the bacteria in vivo appeared to be linked to pH tolerance, adhesion, and antimicrobial properties in vitro.     

Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study

Background

Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance.

Methods

We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis.

Results

Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5–98.8), 80.8% specificity (72.6–87.1), positive likelihood ratio 4.9 (3.4–7.1), negative likelihood ratio 0.083 (0.022–0.32), and misclassification rate 0.20 (standard error 0.038).

Conclusions

In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.     

Macroinvertebrate community responses to land use: a trait-based approach for freshwater biomonitoring in Mongolia

Land-use practices in Mongolia can lead to environmental degradation and consequently affect the structure and function of biological communities. The main aim of this study was to determine land-use effects on freshwater macroinvertebrate communities based on their response to grazing and mining, using a trait-based approach (TBA). The functional structure of macroinvertebrate communities was examined using 86 categories of 16 traits. A total of 13 physical and chemical variables were significantly different among the levels of land-use intensity. Significant declines in functional diversity were observed with increased land-use intensity. The community weighted mean of 19 trait categories for 11 traits varied significantly among different levels of land-use intensity. Traits were significantly explained by environmental variables across a land-use intensity gradient. Water temperature, gravel, nitrate, silt, and cobble were the main predictor variables and explained 28% of the total variance of the trait variation. The functional structure of the macroinvertebrate community was strongly related to environmental conditions. The TBA is an important method in assessing disturbance responses in freshwater communities of steppe and taiga regions, such as in Mongolia and other countries in Central Asia and will be useful in finding best management practices for conserving aquatic ecosystems.