Biology subjects

Watanabe, K.

Publications and source records attributed to Watanabe, K..

At least 127 records · Page 7Linked to original sources

bioRxiv2019

GWAS of brain volume on 54,407 individuals and cross-trait analysis with intelligence identifies shared genomic loci and genes

The phenotypic correlation between human intelligence and brain volume (BV) is considerable (r{approx}0.40), and has been shown to be due to shared genetic factors1. To further examine specific genetic factors driving this correlation, we present genomic analyses of the genetic overlap between intelligence and BV using genome-wide association study (GWAS) results. First, we conducted the largest BV GWAS meta-analysis to date (N=54,407 individuals), followed by functional annotation and gene-mapping. We identified 35 genomic loci (27 novel), implicating 362 genes (346 novel) and 23 biological pathways for BV. Second, we used an existing GWAS for intelligence (N=269,867 individuals2), and estimated the genetic correlation (rg) between BV and intelligence to be 0.23. We show that the rg is driven by physical overlap of GWAS hits in 5 genomic loci. We identified 67 shared genes between BV and intelligence, which are mainly involved in important signaling pathways regulating cell growth. Out of these 67 we prioritized 32 that are most likely to have functional impact. These results provide new information on the genetics of BV and provide biological insight into BVs shared genetic etiology with intelligence.

genetics↗

bioRxiv2019

Feedback loops in the Plk4-STIL-HsSAS6 network coordinate site selection for procentriole formation

Centrioles are duplicated once in every cell cycle, ensuring the bipolarity of the mitotic spindle. Although the core components have been identified, how they cooperate to achieve high fidelity in centriole duplication remains poorly understood. Here, we show that in centriole duplication the accumulation of STIL and HsSAS6, components of the cartwheel structure, provides negative feedback in the centriolar dynamics of Plk4. By live-cell imaging of endogenously tagged proteins in human cells throughout the entire cell cycle, we quantitatively tracked the dynamics of the critical duplication factors: Plk4, STIL, and HsSAS6. Centriolar Plk4 peaks and then starts decreasing during the late G1 phase, which coincides with the accumulation of STIL at centrioles. Shortly thereafter, the HsSAS6 level increases steeply at the procentriole assembly site. We also show that both STIL and HsSAS6 are necessary for attenuating Plk4 levels. Furthermore, our mathematical modeling and simulation convincingly reproduce the dynamics of these three proteins at centrioles, and suggest that the STIL-HsSAS6 complex in the cartwheel has a negative feedback effect on centriolar Plk4. Combined, these findings illustrate how the dynamic behavior of and interactions between the critical duplication factors coordinate the centriole-duplication process.

cell biology↗

bioRxiv2019

OVOL2 induces mesenchymal-to-epithelial transition in fibroblasts and enhances reprogramming to epithelial lineages

Mesenchymal-to-epithelial transition (MET) is an important step in cell reprogramming from fibroblasts (a cell type frequently used for this purpose) to various epithelial cell types. However, the mechanism underlying MET induction in fibroblasts remains to be understood. The present study aimed to identify the transcription factors (TFs) that efficiently induce MET in dermal fibroblasts. OVOL2 was identified as a potent inducer of key epithelial genes, and OVOL2 cooperatively enhanced MET induced by HNF1A, TP63, and KLF4, which are known reprogramming TFs to epithelial lineages. In TP63/KLF4-induced keratinocyte-like cell-state reprogramming, OVOL2 greatly facilitated the activation of epithelial and keratinocyte-specific genes. This was accompanied by enhanced changes in chromatin accessibility across the genome. Mechanistically, motif enrichment analysis revealed that the target loci of KLF4 and TP63 become accessible upon induction of TFs, whereas the OVOL2 target loci become inaccessible. This indicates that KLF4 and TP63 positively regulate keratinocyte-associated genes whereas OVOL2 suppresses fibroblast-associated genes. The exogenous expression of OVOL2 therefore disrupts fibroblast lineage identity and facilitates fibroblast cell reprogramming into epithelial lineages cooperatively with tissue-specific reprogramming factors. Identification of OVOL2 as a MET inducer and an epithelial reprogramming enhancer in fibroblasts provides new insights into cellular reprogramming improvement for future applications.

cell biology↗

bioRxiv2019

FINE-SCALE POPULATION GENETIC STRUCTURE OF DENGUE MOSQUITO VECTOR, Aedes aegypti AND ITS ASSOCIATION TO LOCAL DENGUE INCIDENCE

Dengue fever is an important arthropod-borne disease which is transmitted by the mosquito vector, Aedes aegypti. Vector control programs rely heavily on targeting the mosquito vector in order to stop the disease transmission cycle. Hence, the present study conducted a fine-scale population genetics of Ae. aegypti in a highly urbanized and dengue endemic region in the Philippines. Furthermore, the study also explored the correlation of population genetic indices to the local dengue incidence of the region. The genetic diversity and population structure of Ae. aegypti populations were analyzed by genotyping 11 microsatellite loci from 526 adult mosquitoes sampled in 21 study areas in Metropolitan Manila. Five genetic indices and its dengue incidence were then correlated using Pearsons correlation. Results showed low genetic differentiation among mosquito populations indicating high gene flow activity in the region. However, the study also revealed a considerable number of inferred genetic clusters (K=5). The constructed UPGMA dendrogram exhibited close proximity of genetically-similar Ae. aegypti mosquito populations that extends in long distances suggesting passive dispersal ability of the mosquito vector. Moreover, a positive and significant correlation was observed between dengue incidence and inbreeding coefficient (Fis) (r = 0.52, p = 0.02). Overall, the study showed that population genetic structuring can occur in a fine-scale area which consisted notable clustering and extending patterns of genetically-similar mosquito populations. This infers the potential migration ability of Ae. aegypti in different locations of the region where specific vector control zones could be carried out to disrupt its dispersal ability. Also, this is the first study that attempted to correlate genetic indices to dengue incidence that could serve as a supplementary index in identifying high dengue risk areas in the future. AUTHOR SUMMARYDengue disease puts billions of people worldwide at risk. To mitigate this risk, population genetic studies of its vector, Aedes aegypti, are being conducted. The information established from these studies can be utilized to reduce mosquito population and thereby, reduce the opportunity for dengue transmission. In this study, we used microsatellite markers to determine genetic structure and diversity followed by correlation analyses between genetic indices and dengue incidence. Results show a low genetic differentiation among mosquito populations in Metro Manila; it also indicates population genetic structuring in a fine-scale area. This suggest a pattern of migration activity of Ae. aegpyti which can be used to mitigate dengue transmission. Moreover, the study also explored in correlating genetic indices and local dengue incidence where it demonstrated significant correlation with the inbreeding coefficient (Fis). Further investigation is needed on how these genetic indices may be utilized in predicting and identifying high dengue risk areas in endemic areas.

zoology↗

bioRxiv2019

Species dispersal mediates opposing influences of a branching network on genetic variation in a metapopulation

Aim Fractal networks, represented by branching complexity in rivers, are ubiquitous in nature. In rivers, the number of either distal (e.g., in headwater streams) or confluent (e.g., in mainstems) locations can be increased along with their branching complexity. Distal- or confluent-spatial locations can result in fewer or greater corridor linkages that can alter genetic divergence at the metapopulation scale. These mechanisms underlying the resulting genetic structuring remain poorly understood at the metapopulation scale, particularly in terms of the roles of species-specific dispersal traits. The objective of this study is to mechanistically understand how branching complexity can simultaneously influence genetic divergence in opposite directions.Location Northeastern JapanMethods To evaluate the integrated influences of network complexity and species dispersal on genetic divergence among populations at the catchment scale, we conducted simulation modelling on a mechanistic framework based on Bayesian inference by adapting empirical genetic data from four macroinvertebrate species. Simulations were then done using empirical and virtual species-characteristics on virtual river networks.Results Our novel simulation showed that both greater landscape connectivity (resulting from shorter watercourse distance) and greater isolation of distal locations occurred in the more-branched river networks. These two spatial features have negative and positive influences on genetic divergence, with their relative importance varying among different species and dispersal characteristics. Specifically, genetic divergence at the metapopulation scale increased for species having higher downstream-biased dispersal but decreased for species having higher upstream-biased dispersal. Distal populations (e.g., in headwaters) have higher genetic independence when downstream-biased asymmetry is higher.Main conclusions We found a strong association between species dispersal and evolutionary processes such as gene flow and genetic drift. This association mediates the pervasive influences of branching complexity on genetic-divergence in the metapopulation. It also highlights the importance of considering species dispersal-patterns when developing management strategies in the face of rapid environmental-change scenarios.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗

bioRxiv2019

Higher seroprevalence of Entamoeba histolytica than that of HIV-1 at a voluntary counselling and testing centre in Tokyo

BackgroundAmebiasis, which is caused by Entamoeba histolytica, is a re-emerging public health issue owing to sexually transmitted infection (STI) in Japan. However, epidemiological data are quite limited. MethodologyTo reveal the relative prevalence of sexually transmitted E. histolytica infection to other STIs, we conducted a cross-sectional study at a voluntary counselling and testing (VCT) centre in Tokyo. Seroprevalence of E. histolytica was assessed according to positivity with an enzyme-linked immunosorbent assay for E. histolytica-specific IgG in serum samples collected from anonymous VCT clients. Principal FindingsAmong 2,083 samples, seropositivity for E. histolytica was 2.64%, which was higher than that for HIV-1 (0.34%, p < 0.001) and comparable to that for syphilis (rapid plasma reagin (RPR) 2.11%, p = 0.31). Positivity for Chlamydia trachomatis in urine by transcription-mediated amplification (TMA) was 4.59%. Seropositivity for E. histolytica was high among RPR-or Treponema pallidum hemagglutination (TPHA)-positive individuals and it was not different between clients with and without other STIs. Both seropositivity of E. histolytica and RPR were high among male clients. The seropositive rate for anti-E. histolytica antibody was positively correlated with age. TMA positivity for urine C. trachomatis was high among female clients and negatively correlated with age. Regression analysis identified that male sex, older age, and TPHA-positive results are independent risk factors of E. histolytica seropositivity. ConclusionsSeroprevalence of E. histolytica was 7.9 times higher than that of HIV-1 at a VCT centre in Tokyo, with a tendency to be higher among people at risk for syphilis infection. Author summaryAmebiasis caused by Entamoeba histolytica is an increasingly prevalent sexually transmitted infection (STI) in Japan; however, relative to other STIs, the prevalence of E. histolytica has not been fully assessed. We investigated the seropositivity of E. histolytica using serum samples from 2,083 clients of a voluntary counselling and testing centre in Tokyo. E. histolytica seroprevalence (2.64%) was 7.9 times higher than that of HIV-1 (0.31%) and the same as that of syphilis (rapid plasma reagin: 2.11%). Logistic regression analysis showed that E. histolytica seroprevalence tended to be higher among individuals who were male, older, and positive in Treponema pallidum hemagglutination. These results strongly suggest that public health interventions should be considered to control sexual transmission of E. histolytica infection, which is currently neglected in Japan.

microbiology↗

bioRxiv2019

Knowledge, attitude and practices on dengue fever among paediatric and adult in-patients in Metro Manila, Philippines

Knowledge, attitude and practice (KAP) studies have included mainly community-based samples, yet, investigation on in-patients with Dengue through hospital-based surveillance has not been done. This study aimed to assess and compare the KAP, identify its determinants and protective factors among 250 clinically or serologically confirmed paediatric (n = 233) and adult patients (n = 17) with DF and 250 youth (n = 233) and adult (n = 17) controls. Paediatric patients with DF had significantly higher knowledge and practice mean scores than adult patients with DF and lower practice mean scores than youth controls. Being senior high school, days in the hospital and rash determined increased KAP among paediatric patients with DF. Mosquito-eating fish, screen windows and Dengue vaccine were protective factors against DF, though, further studies should confirm these results. Moreover, there was a significant positive correlation between knowledge and attitude of paediatric patients with DF, however, similar with adult patients with DF, these domains did not correlate with their practices against DF. This suggests that the translation of knowledge and attitude to better practices against DF was poor. Thus, it is necessary to structure health programs on models that facilitate behavioural change among children and adults.

epidemiology↗

bioRxiv2019

Human and mouse iPSC-derived astrocyte subtypes reveal vulnerability in Vanishing White Matter

Astrocytes gained attention as important players in neurological disease, including a number of leukodystrophies. Several studies explored the generation of induced pluripotent stem cell-derived astrocytes for drug screening and regenerative studies. Developing robust models of patient induced pluripotent stem cells is challenged by high variability due to diverse genetic backgrounds and long-term culture procedures. While human models are of special interest, mouse-based models have the advantage that for them these issues are less pronounced. Here we present astrocyte differentiation protocols for both human and mouse induced pluripotent stem cells to specifically induce grey and white matter astrocytes. Both subtypes expressed astrocyte-associated markers, had typical astrocyte morphologies, and gave a reactive response to stress. Importantly, the grey and white matter-like astrocytes differed in size, complexity of processes, and expression profile, conform primary grey and white matter astrocytes. The newly presented mouse and human stem cell-based models for the leukodystrophy Vanishing White Matter replicated earlier findings, such as increased proliferation, decreased OPC maturation and modulation by hyaluronidase. We studied intrinsic astrocyte subtype vulnerability in Vanishing White Matter in both human and mouse cells. Oligodendrocyte maturation was specifically inhibited in cultures with Vanishing White Matter white matter-like astrocytes. By performing RNA sequencing, we found more differentially regulated genes in the white than in the grey matter-like astrocytes. Human and mouse astrocytes showed the same affected pathways, although human white matter-like astrocytes presented human-specific disease mechanisms involved in Vanishing White Matter. Using both human and mouse induced pluripotent stem cells, our study presents protocols to generate white and grey matter-like astrocytes, and shows astrocyte subtype-specific defects in Vanishing White Matter. While mouse induced pluripotent stem cell-based cultures may be less suitable to mimic human astrocyte subtype- or patient-specific changes, they might more robustly represent disease mutation-related cellular phenotypes as the cells are derived from inbred mice and the protocols are faster. The presented models give new tools to generate astrocyte subtypes for in vitro disease modeling and in vivo regenerative applications.

neuroscience↗

bioRxiv2018

A global view of pleiotropy and genetic architecture in complex traits

After a decade of genome-wide association studies (GWASs), fundamental questions in human genetics are still unanswered, such as the extent of pleiotropy across the genome, the nature of trait-associated genetic variants and the disparate genetic architecture across human traits. The current availability of hundreds of GWAS results provide the unique opportunity to gain insight into these questions. In this study, we harmonized and systematically analysed 4,155 publicly available GWASs. For a subset of well-powered GWAS on 558 unique traits, we provide an extensive overview of pleiotropy and genetic architecture. We show that trait associated loci cover more than half of the genome, and 90% of those loci are associated with multiple trait domains. We further show that potential causal genetic variants are enriched in coding and flanking regions, as well as in regulatory elements, and how trait-polygenicity is related to an estimate of the required sample size to detect 90% of causal genetic variants. Our results provide novel insights into how genetic variation contributes to trait variation. All GWAS results can be queried and visualized at the GWAS ATLAS resource (http://atlas.ctglab.nl).

genetics↗

bioRxiv2018

Gut microbiome communication with bone marrow regulates susceptibility to amebiasis

The gut microbiome provides resistance to infection. However, the mechanisms for this are poorly understood. Colonization with the intestinal bacterium Clostridium scindens provided protection from the parasite Entamoeba histolytica via innate immunity. Introduction of C. scindens into the gut microbiota epigenetically altered and expanded bone marrow granulocyte-monocyte-progenitors (GMPs) and provided neutrophil-mediated protection against subsequent challenge with E. histolytica. Adoptive transfer of bone-marrow from C. scindens colonized-mice into naive-mice protected against ameba infection and increased intestinal neutrophils. Because of the known ability of C. scindens to metabolize the bile salt cholate, we measured deoxycholate and discovered that it was increased in the sera of C. scindens colonized mice, as well as in children protected from amebiasis. Administration of deoxycholate alone (in the absence of C. scindens) increased the epigenetic mediator JMJD3 and GMPs and provided protection from amebiasis. In conclusion the microbiota was shown to communicate to the bone marrow via microbially-metabolized bile salts to train innate immune memory to provide antigen-nonspecific protection from subsequent infection. This represents a novel mechanism by which the microbiome protects from disease.\n\nOne Sentence SummaryIntroduction of the human commensal bacteria Clostridium scindens into the intestinal microbiota epigenetically alters bone marrow and protects from future parasite infection.

microbiology↗

bioRxiv2018

Genome-wide signatures of local adaptation among seven stoneflies species along a nationwide latitudinal gradient in Japan

BackgroundEnvironmental heterogeneity continuously produces a selective pressure that results in genomic variation among organisms; understanding this relationship remains a challenge in evolutionary biology. Here, we evaluated the degree of genome-environmental association of seven stonefly species across a wide geographic area in Japan and additionally identified putative environmental drivers and their effect on co-existing multiple stonefly species. Double-digest restriction-associated DNA (ddRAD) libraries were independently sequenced for 219 individuals from 23 sites across four geographical regions along a nationwide latitudinal gradient in Japan.\n\nResultsA total of 4,251 candidate single nucleotide polymorphisms (SNPs) strongly associated with local adaptation were discovered using Latent mixed models; of these, 294 SNPs showed strong correlation with environmental variables, specifically precipitation and altitude, using distance-based redundancy analysis. Genome-genome comparison among the seven species revealed a high sequence similarity of candidate SNPs within a geographical region, suggesting the occurrence of a parallel evolution process.\n\nConclusionsOur results revealed genomic signatures of local adaptation and their influence on multiple, co-occurring species. These results can be potentially applied for future studies on river management and climatic stressor impacts.

genomics↗

bioRxiv2018

Molecular phylogeny and diversification timing of the Nemouridae family (Insecta, Plecoptera) in the Japanese Archipelago

The generation of the high species diversity of insects in Japan was profoundly influenced by the formation of the Japanese Archipelago. We explored the species diversification and biogeographical history of the Nemouridae family in the Japanese Archipelago using mitochondrial DNA and nuclear DNA markers. We collected 49 species among four genera: Indonemoura, Protonemura, Amphinemura and Nemoura in Japan, China, South Korea and North America. We estimated their divergence times--based on three molecular clock node calibrations--using Bayesian phylogeography approaches. Our results suggested that Japanese Archipelago formation events resulted in diversification events in the middle of the Cretaceous (<120 Ma), speciation in the Paleogene (<50 Ma) and intra-species diversification segregated into eastern and western Japan of the Fossa Magna region at late Neogene (20 Ma). The Indonemoura samples were genetically separated into two clades--that of Mainland China and that of Japan. The Japanese clade clustered with the Nemouridae species from North America, suggesting the possibility of a colonisation event prior to the formation of the Japanese Archipelago. We believe that our results enhanced the understanding both of the origin of the species and of local species distribution in the Japanese Archipelago.

evolutionary biology↗

bioRxiv2018

Comparison of DNA metabarcoding and morphological identification for stream macroinvertebrate biodiversity assessment and monitoring

Conventional morphology-based identification is commonly used for routine assessment of freshwater ecosystems. However, cost and time efficient techniques such as high-throughput sequencing (HTS) based approaches may resolve the constraints encountered in conducting morphology-based surveys. Here, we characterized stream macroinvertebrate species diversity and community composition via metabarcoding and morphological analysis from environmental samples collected from the Shigenobu River Basin in Ehime Prefecture, Japan. We compared diversity metrics and assessed both approaches ability to evaluate the relationship between macroinvertebrate community and environmental variables. In total, we morphologically identified 45 taxa (3 families, six subfamilies, 31 genera, and five species) from 8,276 collected individuals from ten study sites. We detected 44 species by metabarcoding, with 35 species collapsed into 11 groups matching the morphologically identified taxa. A significant positive correlation between logged depth (number of HTS reads) and abundance of morphological taxa was observed, which implied that quantitative data can be used for subsequent analyses. Relatively higher estimates of alpha diversity were calculated from the metabarcoding data in comparison to morphology-based data. However, beta diversity estimates between metabarcoding and morphology data based on both incidence and abundance-based matrices were correlated proving that community differences between sampling sites were preserved in the molecular data. Also, both models were significant, but metabarcoding data (93%) explained a relatively higher percentage of variation in the relationship between community composition and the environmental variables than morphological data (91%). Overall, we present both the feasibility and limitations of HTS-driven estimations of taxonomic richness, community composition, and diversity metrics, and that metabarcoding was proven comparable and more sensitive against morphology-based analysis for stream macroinvertebrate biodiversity assessment and environmental monitoring.

ecology↗

bioRxiv2018

Using Google Trends to Examine the Spatio-Temporal Incidence and Behavioral Patterns of Dengue Disease: A Case Study in Metropolitan Manila, Philippines

Dengue is a major public health concern and an economic burden in the Philippines. Despite the countrys improved dengue surveillance, it still suffers from various setbacks and therefore needs to be complemented with alternative approaches. Previous studies have demonstrated the potential of internet-based surveillance such as Google Dengue Trends (GDT) in supplementing current epidemiological methods for predicting future dengue outbreaks and patterns. With this, our study aims to assess the temporal relationship of GDT and dengue incidence in Metropolitan Manila from previous years and examine web search behavior of the population towards the disease. The study collated and organized the population statistics and reported dengue cases in Metropolitan Manila from respective government agencies to calculate the spatial and temporal dengue incidence. The relative search volume of the term dengue and top dengue-related search queries in Metropolitan Manila were obtained and organized from the Google trends platform. Data processing of GDT and dengue incidence was performed by conducting an adjustment procedure and subsequently used for correlation and cross-correlation analyses. Moreover, a thematic analysis was employed on the top dengue-related search queries. Results revealed a high temporal relationship between GDT and dengue incidence when either one of the variables is adjusted. Cross-correlation showed that there is delayed effect (1-2 weeks) of GDT to dengue incidence, demonstrating its potential in predicting future dengue outbreaks and patterns in Metropolitan Manila. Thematic analysis of dengue-related search queries indicated 5 categories namely; (a) dengue, (b) sign and symptoms of dengue, (c) treatment and prevention, (d) mosquito and (e) other diseases where the majority of the search queries was signs and symptoms which indicate the health-seeking behavior of the population towards the disease.

epidemiology↗

bioRxiv2018

Detection of adaptive divergence in populations of the stream mayfly Ephemera strigata with machine learning

Adaptive divergence is a key mechanism shaping the genetic variation of natural populations. A central question linking ecology with evolutionary biology concerns the role of environmental heterogeneity in determining adaptive divergence among local populations within a species. In this study, we examined adaptive the divergence among populations of the stream mayfly Ephemera strigata in the Natori River Basin in northeastern Japan. We used a genome scanning approach to detect candidate loci under selection and then applied a machine learning method (i.e. Random Forest) and traditional distance-based redundancy analysis (dbRDA) to examine relationships between environmental factors and adaptive divergence at non-neutral loci. We also assessed spatial autocorrelation at neutral loci to quantify the dispersal ability of E. strigata. Our main findings were as follows: 1) random forest shows a higher resolution than traditional statistical analysis for detecting adaptive divergence; 2) separating markers into neutral and non-neutral loci provides insights into genetic diversity, local adaptation and dispersal ability and 3) E. strigata shows altitudinal adaptive divergence among the populations in the Natori River Basin.

evolutionary biology↗

bioRxiv2018

Cortical control of locomotor muscle activity through muscle synergies in humans: a neural decoding study

Walking movements are orchestrated by the activation of a large number of muscles. The control of numerous muscles during walking is believed to be simplified by flexible activation of groups of muscles called muscle synergies. Although significant corticomuscular connectivity during walking has been reported, the level at which the cortex controls locomotor muscle activity (i.e., muscle synergy or individual muscle level) remains unclear. Here, we examined cortical involvement in muscle control during walking by brain decoding of the activation of muscle synergies and individual muscles from electroencephalographic (EEG) signals using linear decoder models. First, we demonstrated that activation of locomotor muscle synergies was decoded from slow cortical waves with significant accuracy. In addition, we found that decoding accuracy for muscle synergy activation was greater than that for individual muscle activation and that decoding of individual muscle activation was based on muscle synergy-related cortical information. Taken together, these results provide indirect evidence that the cerebral cortex hierarchically controls multiple muscles through a few muscle synergies during walking. Our findings extend the current understanding of the role of the cortex in muscular control during walking and could accelerate the development of effective brain-machine interfaces for people with locomotor disabilities.

neuroscience↗

bioRxiv2018

DETECTION OF Wolbachia IN FIELD-COLLECTED MOSQUITO VECTOR, Aedes aegypti

It was the impression from past literature that Wolbachia is not naturally found in Ae. aegypti. However, there are have been reports that recently reveals the presence of this endosymbiont in this mosquito vector. With this, our study presents additional support of Wolbachia infection in Ae. aegypti by screening field-collected adult mosquitoes using Wolbachiaspecific 16S rDNA and its surface protein (wsp) makers under optimized PCR conditions. From a total of 672 Ae. aegpyti adult mosquito samples collected in Metropolitan Manila, Philippines, 113 (16.8%) and 89 (13.2%) individual mosquito samples were determined to be Wolbachia infected using the wsp and 16S rDNA markers, respectively. The Ae. aegpyti wsp sample sequences were similar or identical to five known Wolbachia strains belonging to supergroups A or B while majority of 16S rDNA sample sequences were similar to strains belonging to supergroup B. Overall, 80 (11.90%) individual mosquito samples revealed to show positive amplifications in both markers and 69.0% showed congruence in supergroup identification (supergroup B). Our findings illustrate that the infection status of Wolbachia in Ae. aegypti may appear common than previously recognized.

microbiology↗

bioRxiv2018

Cryo-EM structure of the volume-regulated anion channel LRRC8

Maintenance of cell volume against osmotic change is crucial for proper cell functions, such as cell proliferation and migration. The leucine-rich repeat-containing 8 (LRRC8) proteins are anion selective channels, and were recently identified as pore components of the volume-regulated anion channels (VRACs), which extrude anions to decrease the cell volume upon cell-swelling. Here, we present the human LRRC8A structure, determined by a single-particle cryo-electron microscopy analysis. The sea anemone-like structure represents a trimer of dimers assembly, rather than a symmetrical hexameric assembly. The four-spanning transmembrane region has a gap junction channel-like membrane topology, while the LRR region containing 15 leucine-rich repeats forms a long twisted arc. The channel pore is along the central axis and constricted on the extracellular side, where the highly conserved polar and charged residues at the tip of the extracellular helix contribute to the anion and other osmolyte permeability. Comparing the two structural populations facilitated the identification of both compact and relaxed conformations, suggesting that the LRR region is flexible and mobile with rigid-body motions, which might be implicated in structural transitions upon pore opening. Overall, our structure provides a framework for understanding the molecular mechanisms of this unique class of ion channels.

molecular biology↗