Mosquito control actions affect chironomid diversity in temporary wetlands of the Upper Rhine Valley

The Upper Rhine Valley, a “hotspot of biodiversity” in Germany, has been treated with the biocide Bacillus thuringiensis var. israelensis (Bti) for mosquito control for decades. Previous studies discovered Bti nontarget effects in terms of severe chironomid abundance reductions. In this study, we investigated the impact of Bti on species level and addressed the community composition of the nontarget family Chironomidae by use of community metabarcoding. Chironomid emergence data were collected in three mosquito‐control relevant wetland types in the Upper Rhine Valley. For all three sites the chironomid species composition, based on operational taxonomic units (OTUs), was different to varying degrees in the Bti‐treated samples versus control samples, ranging from a significant 63% OTU reduction to an OTU replacement. We assumed that predatory chironomids are less prone to Bti than filter feeders, as the latter feed on floating particles leading to direct ingestion of Bti. However, a comparable percentage of predators and filter feeders (63% and 65%, respectively) was reduced in the Bti samples, suggesting that the feeding strategy is not the main driver for Bti sensitivity in chironomids. Finally, our data was compared to a three‐year‐old data set, indicating possible chironomid community recovery due to species recolonization a few years after the last Bti application. Considering the currently discussed worldwide insect decline we recommend a rethinking of the usage of the biocide Bti, and to prevent its ongoing application especially in nature protection reserves to enhance ecological resilience and to prevent boosting the current biodiversity loss.     

Streptococcal dTDP‐L‐rhamnose biosynthesis enzymes: functional characterization and lead compound identification

Biosynthesis of the nucleotide sugar precursor dTDP‐L‐rhamnose is critical for the viability and virulence of many human pathogenic bacteria, including Streptococcus pyogenes (Group A Streptococcus; GAS), Streptococcus mutans and Mycobacterium tuberculosis. Streptococcal pathogens require dTDP‐L‐rhamnose for the production of structurally similar rhamnose polysaccharides in their cell wall. Via heterologous expression in S. mutans, we confirmed that GAS RmlB and RmlC are critical for dTDP‐L‐rhamnose biosynthesis through their action as dTDP‐glucose‐4,6‐dehydratase and dTDP‐4‐keto‐6‐deoxyglucose‐3,5‐epimerase enzymes respectively. Complementation with GAS RmlB and RmlC containing specific point mutations corroborated the conservation of previous identified catalytic residues. Bio‐layer interferometry was used to identify and confirm inhibitory lead compounds that bind to GAS dTDP‐rhamnose biosynthesis enzymes RmlB, RmlC and GacA. One of the identified compounds, Ri03, inhibited growth of GAS, other rhamnose‐dependent streptococcal pathogens as well as M. tuberculosis with an IC₅₀ of 120–410 µM. Importantly, we confirmed that Ri03 inhibited dTDP‐L‐rhamnose formation in a concentration‐dependent manner through a biochemical assay with recombinant rhamnose biosynthesis enzymes. We therefore conclude that inhibitors of dTDP‐L‐rhamnose biosynthesis, such as Ri03, affect streptococcal and mycobacterial viability and can serve as lead compounds for the development of a new class of antibiotics that targets dTDP‐rhamnose biosynthesis in pathogenic bacteria.     

Functioning of plant-bacterial associations under osmotic stress in vitro

World Journal of Microbiology and Biotechnology - Derived from RNA, 5?-ribonucleotides, especially Inosine-5?-monophosphate (IMP) and guanosine-5?-monophosphate (GMP), can enhance...     

Variation in human hair ultrastructure among three biogeographic populations

Human scalp hairs are often examined microscopically to study the variation and diversity among a range of visible morphological traits. In this study, we focused on the ultrastructure of human scalp hair within its keratinized matrix, emphasizing, the density and distribution of melanosomes, variation in cuticle thickness within populations, and the relationship of hair fiber ultrastructure with biogeographic ancestry. We used transmission electron microscopy (TEM) to visualize hair cross-sections and generate micron-scale resolution images for analysis of particle morphology and the layered hair matrix. Our results revealed considerable variation in all parameters examined, including the relationship of ultrastructure to biogeographic ancestry. Among the three metapopulations studied (European, African, and East Asian), we identified hair cross-sectional shape, cuticle dimensions, and melanosome distribution as traits that reveal statistically significant ancestry-related patterns. This study establishes trait patterns in hair morphology and ultrastructure among three biogeographically defined metapopulations to improve the current understanding of human variation in hair form and establish a foundation for future studies on the genetic and developmental bases of phenotypic variation in hair ultrastructure related to genotype.     

Arbovirus surveillance using FTATM cards in modified CO2‐baited encephalitis virus surveillance traps in the Northern Territory,Australia

In 2016, modified CO₂‐baited encephalitis virus surveillance (EVS) traps were evaluated for flavivirus surveillance in the Northern Territory, Australia. The traps were fitted with honey‐soaked nucleic acid preservation cards (FTA^TM) for mosquitoes to expectorate virus while feeding on the cards. Cards were tested for the presence of selected arboviruses, with two cards testing positive for Kunjin virus and Alfuy, while sentinel chickens tested in parallel also showed Kunjin virus activity at the same time. The results from the cards and vector mosquito feeding rates indicate that CO₂‐baited EVS traps coupled with honey‐baited FTA^TM cards are an effective tool for broad‐scale arbovirus surveillance.     

Wolbachia infection can bias estimates of intralocus sexual conflict

Males and females share most of their genome and develop many of the same traits. However, each sex frequently has different optimal values for these shared traits, creating intralocus sexual conflict. This conflict has been observed in wild and laboratory populations of insects and affects important evolutionary processes such as sexual selection, the maintenance of genetic variation, and possibly even speciation. Given the broad impacts of intralocus conflict, accurately detecting and measuring it is important. A common way to detect intralocus sexual conflict is to calculate the intersexual genetic correlation for fitness, with negative values suggesting conflict. Here, we highlight a potential confounder of this measure—cytoplasmic incompatibility caused by the intracellular parasite Wolbachia. Infection with Wolbachia can generate negative intersexual genetic correlations for fitness in insects, suggestive of intralocus sexual conflict. This is because cytoplasmic incompatibility reduces the fitness of uninfected females mated to infected males, while uninfected males will not suffer reductions in fitness if they mate with infected females and may even be fitter than infected males. This can lead to strong negative intersexual genetic correlations for fitness, mimicking intralocus conflict. We illustrate this issue using simulations and then present Drosophila simulans data that show how reproductive incompatibilities caused by Wolbachia infection can generate signals of intralocus sexual conflict. Given that Wolbachia infection in insect populations is pervasive, but populations usually contain both infected and uninfected individuals providing scope for cytoplasmic incompatibility, this is an important consideration for sexual conflict research but one which, to date, has been largely underappreciated.     

Estimating the impact of divergent mating phenology between residents and migrants on the potential for gene flow

Gene flow between populations can allow the spread of beneficial alleles and genetic diversity between populations, with importance to conservation, invasion biology, and agriculture. Levels of gene flow between populations vary not only with distance, but also with divergence in reproductive phenology. Since phenology is often locally adapted, arriving migrants may be reproductively out of synch with residents, which can depress realized gene flow. In flowering plants, the potential impact of phenological divergence on hybridization between populations can be predicted from overlap in flowering schedules—the daily count of flowers capable of pollen exchange—between a resident and migrant population. The accuracy of this prospective hybridization estimate, based on parental phenotypes, rests upon the assumptions of unbiased pollen transfer between resident and migrant active flowers. We tested the impact of phenological divergence on resident–migrant mating frequencies in experiments that mimicked a single large gene flow event. We first prospectively estimated mating frequencies two lines of Brassica rapaselected or early and late flowering. We then estimated realized mating frequencies retrospectively through progeny testing. The two estimates strongly agreed in a greenhouse experiment, where procedures ensured saturating, unbiased pollination. Under natural pollination in the field, the rate of resident–migrant mating, was lower than estimated by phenological divergence alone, although prospective and retrospective estimates were correlated. In both experiments, differences between residents and migrants in flowering schedule shape led to asymmetric hybridization. Results suggest that a prospective estimate of hybridization based on mating schedules can be a useful, although imperfect, tool for evaluating potential gene flow. They also illustrate the impact of mating phenology on the magnitude and symmetry of reproductive isolation.     

Sequential development of several RT-qPCR tests using LNA nucleotides and dual probe technology to differentiate SARS-CoV-2 from influenza A and B

Sensitive and accurate RT-qPCR tests are the primary diagnostic tools to identify SARS-CoV-2-infected patients. While many SARS-CoV-2 RT-qPCR tests are available, there are significant differences in test sensitivity, workflow (e.g. hands-on-time), gene targets and other functionalities that users must consider. Several publicly available protocols shared by reference labs and public health authorities provide useful tools for SARS-CoV-2 diagnosis, but many have shortcomings related to sensitivity and laborious workflows. Here, we describe a series of SARS-CoV-2 RT-qPCR tests that are originally based on the protocol targeting regions of the RNA-dependent RNA polymerase (RdRp) and envelope (E) coding genes developed by the Charité Berlin. We redesigned the primers/probes, utilized locked nucleic acid nucleotides, incorporated dual probe technology and conducted extensive optimizations of reaction conditions to enhance the sensitivity and specificity of these tests. By incorporating an RNase P internal control and developing multiplexed assays for distinguishing SARS-CoV-2 and influenza A and B, we streamlined the workflow to provide quicker results and reduced consumable costs. Some of these tests use modified enzymes enabling the formulation of a room temperature-stable master mix and lyophilized positive control, thus increasing the functionality of the test and eliminating cold chain shipping and storage. Moreover, a rapid, RNA extraction-free version enables high sensitivity detection of SARS-CoV-2 in about an hour using minimally invasive, self-collected gargle samples. These RT-qPCR assays can easily be implemented in any diagnostic laboratory and can provide a powerful tool to detect SARS-CoV-2 and the most common seasonal influenzas during the vaccination phase of the pandemic.     

The structure of the O-polysaccharide from the lipopolysaccharide of Providencia alcalifaciens O36 containing 3-deoxy-d-manno-oct-2-ulosonic acid

An oligosaccharide that corresponds to the repeating unit of the O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O36. Structural studies of the oligosaccharide and O-deacylated lipopolysaccharide were performed using sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, and H-detected (1)H,(13)C HSQC and HMBC experiments. It was found that the O-polysaccharide is built up of linear trisaccharide repeating units containing 2-acetamido-2-deoxyglucose, 6-deoxy-l-talose (l-6dTal), and 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) and has the following structure. [structure: see text]     

Structure of the O-polysaccharide and serological cross-reactivity of the lipopolysaccharide of Providencia alcalifaciens O32 containing N-acetylisomuramic acid

The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O32 and studied by sugar and methylation analyses, solvolysis with triflic acid, 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY, TOCSY, ROESY, H-detected 1H,13C HSQC and HMBC experiments. It was found that the polysaccharide has a branched tetrasaccharide repeating unit containing 2-acetamido-3-O-[(S)-1-carboxyethyl]-2-deoxy-D-glucose (D-GlcNAc3Slac, N-acetylisomuramic acid) with the following structure: [STRUCTURE: SEE TEXT]. Serological studies with O-antisera showed antigenic relationships between P. alcalifaciens O32 and O29 as well as several other Providencia and Proteus strains sharing putative epitopes on the O-polysaccharides.