Transient Membrane Localization of SPV-1 Drives Cyclical Actomyosin Contractions in the C. elegans Spermatheca

SummaryBackgroundActomyosin contractility is the major cellular force driving changes in cell and tissue shape. A principal regulator of contractility is the small GTPase RhoA. External mechanical forces have been shown to impact RhoA activity and cellular contractility. However, the mechanotransduction pathway from external forces to actomyosin contractility is poorly understood.ResultsHere, we show that actomyosin contractility in the C. elegans spermatheca is under control of RHO-1/RhoA, which, in turn, is regulated by the F-BAR and RhoGAP protein SPV-1. In the relaxed spermatheca, SPV-1 localizes through its F-BAR domain to the apical membrane, where it inhibits RHO-1/RhoA activity through its RhoGAP domain. Oocyte entry forces the spermatheca cells to stretch, and subsequently SPV-1 detaches from the membrane, permitting RHO-1 activity to increase. The increase in RHO-1 activity facilitates spermatheca contraction and expulsion of the newly fertilized embryo into the uterus, leading to relaxation of the spermatheca, SPV-1 membrane localization, and initiation of a new cycle.ConclusionsOur results demonstrate how transient membrane localization of a novel F-BAR domain, likely via specific binding to curved membranes, coupled to a RhoGAP domain, can provide feedback between a mechanical signal (membrane stretching) and actomyosin contractility. We anticipate this to be a widely utilized feedback mechanism used to balance actomyosin forces in the face of externally applied forces, as well as intrinsic processes involving cell deformation, from single-cell migration to tissue morphogenesis

CYCLICAL REGULATION OF A CONTRACTILE TUBE: INSIGHTS FROM THE CAENORHABDITIS ELEGANS SPERMATHECA

Ph.DPH.D. IN MECHANOBIOLOGY (NGS

Analysis of Resistance to Clarithromycin and Virulence Markers in Helicobacter pylori Clinical Isolates from Eastern Taiwan

AbstractObjectiveLittle information is available concerning the relationships between clarithromycin resistance and virulence marker genes (iceA, cagA and vacA) in Helicobacter pylori isolated in Taiwan. The aim of this study was to evaluate the possible association between clarithromycin resistance and genotypes of the virulence markers on clarithromycin-resistant H. pylori isolates obtained in eastern TaiwanMaterials and MethodsThe genotypes of the virulence marker genes (iceA, cagA and vacA) were analyzed by PCR, and the 23S rDNA region from 18 clarithromycin-resistant clinical isolates of H. pylori was amplified by PCR and sequenced.ResultsPoint mutations were found to occur in all isolates. Two isolates had A2143G, six had T2182C, one had C2227T, six had A2143G plus T2182C, and three had heterozygous alleles. The latter included a wild-type allele (A2143) plus (i) an A2143G, (ii) an A2143G plus an A2223G, and (iii) an A2143G plus a T2182C. The prevalence of the marker genes cagA, iceA1, iceA2, and both iceA1 and iceA2, in the isolates was 95.5%, 66.9%, 7.5%, and 25.6%, respectively. The vacAs1 allele was detected in all isolates, whereas the m1 and m2 alleles were found in 44.4% and 55.6% of the isolates, respectivelyConclusionThere were no significant associations between clarithromycin resistance and the presence of the cagA gene, vacA allele mosaicism, and the iceA genotypes. The most notable finding of our study was that the C2227T single mutation in 23S rDNA could also be related to the high clarithromycin minimal inhibitory concentrations in clinical isolates from eastern Taiwan

Social capital in the prevention and management of non-communicable diseases among migrants and refugees: a systematic review and meta-ethnography.

Globally, the burden of non-communicable diseases (NCDs) falls disproportionately on underserved populations. Migrants and refugees are particularly vulnerable due to economic instability and systemic poverty. Despite the myriad of health risks faced by migrants and refugees, access to appropriate healthcare is hindered by structural, cultural and socioeconomic barriers. We conducted a systematic review and meta-ethnography to obtain critical insight into how the interplay of social capital and structural factors (eg, state policies and socioeconomic disadvantage) influences the prevention and treatment of NCDs in migrant and refugee populations. We included 26 studies of 14 794 identified articles, which reported qualitative findings on the structure and functions of social capital in NCD prevention and management among migrants and refugees. We synthesised findings, using the process outlined by Noblit and Hare, which indicated that migrants and refugees experienced weakened social networks in postmigration settings. They faced multiple barriers in healthcare access and difficulty navigating healthcare systems perceived as complex. Family as the core of social capital appeared of mixed value in their NCD prevention and management, interacting with cultural dissonance and economic stress. Community organisations were integral in brokering healthcare access, especially for information diffusion and logistics. Healthcare providers, especially general practitioners, were important bridges providing service-user education and ensuring a full continuum of quality care. While social capital reduced immediate barriers in healthcare access for NCD prevention and management, it was insufficient to address structural barriers. System-level interventions appear necessary to achieve equitable healthcare access in host countries. PROSPERO registration number: CCRD42020167846

Shipping routes in the South China Sea and northern Indian Ocean and associated monsoonal influences

The major shipping routes of the South China Sea (SCS) and northern Indian Ocean (NIO) are analyzed via ship observations compiled by the International Comprehensive Ocean-Atmosphere Data Set. In the SCS, one route from the East China Sea moves through the Taiwan Strait toward Hong Kong and Singapore. The other route from the Pacific moves passed the east coast of Taiwan and through the Bashi Channel/Luzon Strait to Singapore. After Singapore, the shipping routes pass through the Strait of Malacca to Sri Lanka. In the Arabian Sea, ships from Sri Lanka go either northwestward toward the Persian Gulf or westward toward the Red Sea. A northeast-southwest route connects the Persian Gulf and the Red Sea. The resultant routes exhibit a triangular pattern in the Arabian Sea. Monsoonal influences on shipping routes are evident in the Arabian Sea, but indiscernible in the SCS. In summer, the southwest monsoon causes strong winds and waves over the western-central Arabian Sea. Ships detour from the southern side of Socotra Island to the northern side. The northern side is on the leeside of the intruding southwesterly flows and has weaker winds and waves than the windward southern side. In the SCS, the winter northeasterly flows intensify winds and waves over two strait regions: the Taiwan Strait and the Luzon Strait. These straits are at the conjunction of the Pacific and the SCS. Routes passing through these straits have the advantage of a short, straight navigation path. Moreover, the winds and waves over these regions are not as strong as those occurring in the Arabian Sea during summer. The maritime conditions in the SCS are not dangerous enough to necessitate a detour

Maximum power point tracking of partially shaded photovoltaic arrays using particle swarm optimization

This paper presents the particle swarm optimization based maximum power point tracking (MPPT) approach for maximizing output power of photovoltaic (PV) array under partially shaded conditions (PSC). During PSC, the P-V characteristic becomes more complex with multiple maximum power points (MPP). Most of the conventional MPPT approaches will be trapped at the local MPP and hence limiting the maximum power generation. As such, the investigation on particle swarm optimization (PSO) based MPPT is carried out to maximize the PV generated power principally under PSC operation. The performances of conventional MPPT approach and the proposed PSO-MPPT are investigated particularly on the transient and steady state responses under various shaded conditions. The simulation results show that the PSO-MPPT is able to facilitate the PV array to reach the global MPP as well as to assist the PV array to produce more stable output power compared to the conventional perturb and observe (P&O) algorithm

Impaired colonic motility in high-glycemic diet-induced diabetic mice is associated with disrupted gut microbiota and neuromuscular function

Background: Similar to the high-fat diet (HFD), the high-glycemic diet (HGD) contributes to the development and progression of type 2 diabetes mellitus (T2DM). However, the effect of HGD on gastrointestinal motility in T2DM and its u nderlying mechanisms remain unclear. Methods: Thirty C57BL/6J mice were randomly designated into the normal-feeding diet (NFD) group, HFD group, and HGD group. The plasma glucose, plasma insulin, and gastrointestinal motility were examined. Meanwhile, the tension of isolated colonic smooth muscle rings was calculated, and the gut microbiota was analyzed by 16s rDNA high-throughput sequencing. Result: After 16 weeks of HGD feeding, obesity, hyperglycemia, insulin resistance, and constipation were observed in HGD mice. Autonomic contraction frequency of the colonic neuromuscular system and electrical field stimulation-induced contractions were reduced in HGD mice. On the contrary, neuronal nitric oxide synthase activity and neuromuscular relaxation were found to be enhanced. Finally, gut microbiota analysis revealed that Rhodospirillaceae abundance significantly increased at the family level in HGD mice. At the genus level, the abundance of Insolitispirillum increased remarkably, whereas Turicibacter abundance decreased significantly in HGD mice. Conclusion: HGD induced constipation in obese diabetic mice, which we speculated that it may be related to neuromuscular dysmotility and intestinal microbiota dysbiosis