Control of brown dog tick,Rhipicephalus sanguineus using assembly pheromone encapsulated in natural polymer,chitosan

In the current study, an attempt was made to encapsulate assembly pheromone using natural polymer, chitosan. Chitosan beads were prepared by incorporating assembly pheromone in conjunction with an acaricide, namely, deltamethrin. In the in vitro bioassay, the test beads attracted and killed 79 % of unfed larvae, 88 % of unfed nymphs and 61 % of unfed adults of the brown dog tick, Rhipicephalus sanguineus, in 24 h of exposure. Field trials were carried out to attract and kill the pre-parasitic environmental stages. The beads were dispersed onto specially designed devices and they were placed in infested kennels. The devices were observed after 10 days.     

Differential Diagnosis of Malaria on Truelab Uno?, a Portable,Real-Time,MicroPCR Device for Point-Of-Care Applications

Background

Sensitive and specific detection of malarial parasites is crucial in controlling the significant malaria burden in the developing world. Also important is being able to identify life threatening Plasmodium falciparum malaria quickly and accurately to reduce malaria related mortality. Existing methods such as microscopy and rapid diagnostic tests (RDTs) have major shortcomings. Here, we describe a new real-time PCR-based diagnostic test device at point-of-care service for resource-limited settings.

Methods

Truenat^® Malaria, a chip-based microPCR test, was developed by bigtec Labs, Bangalore, India, for differential identification of Plasmodium falciparum and Plasmodium vivax parasites. The Truenat Malaria tests runs on bigtec’s Truelab Uno^® microPCR device, a handheld, battery operated, and easy-to-use real-time microPCR device. The performance of Truenat^® Malaria was evaluated versus the WHO nested PCR protocol. The Truenat^® Malaria was further evaluated in a triple-blinded study design using a sample panel of 281 specimens created from the clinical samples characterized by expert microscopy and a rapid diagnostic test kit by the National Institute of Malaria Research (NIMR). A comparative evaluation was done on the Truelab Uno^® and a commercial real-time PCR system.

Results

The limit of detection of the Truenat Malaria assay was found to be <5 parasites/μl for both P. falciparum and P. vivax. The Truenat^® Malaria test was found to have sensitivity and specificity of 100% each, compared to the WHO nested PCR protocol based on the evaluation of 100 samples. The sensitivity using expert microscopy as the reference standard was determined to be around 99.3% (95% CI: 95.5–99.9) at the species level. Mixed infections were identified more accurately by Truenat Malaria (32 samples identified as mixed) versus expert microscopy and RDTs which detected 4 and 5 mixed samples, respectively.

Conclusion

The Truenat^® Malaria microPCR test is a valuable diagnostic tool and implementation should be considered not only for malaria diagnosis but also for active surveillance and epidemiological intervention.     

Factors associated with excess all-cause mortality in the first wave of the COVID-19 pandemic in the UK: A time series analysis using the Clinical Practice Research Datalink

BackgroundExcess mortality captures the total effect of the Coronavirus Disease 2019 (COVID-19) pandemic on mortality and is not affected by misspecification of cause of death. We aimed to describe how health and demographic factors were associated with excess mortality during, compared to before, the pandemic.Methods and findingsWe analysed a time series dataset including 9,635,613 adults (≥40 years old) registered at United Kingdom general practices contributing to the Clinical Practice Research Datalink. We extracted weekly numbers of deaths and numbers at risk between March 2015 and July 2020, stratified by individual-level factors. Excess mortality during Wave 1 of the UK pandemic (5 March to 27 May 2020) compared to the prepandemic period was estimated using seasonally adjusted negative binomial regression models. Relative rates (RRs) of death for a range of factors were estimated before and during Wave 1 by including interaction terms. We found that all-cause mortality increased by 43% (95% CI 40% to 47%) during Wave 1 compared with prepandemic. Changes to the RR of death associated with most sociodemographic and clinical characteristics were small during Wave 1 compared with prepandemic. However, the mortality RR associated with dementia markedly increased (RR for dementia versus no dementia prepandemic: 3.5, 95% CI 3.4 to 3.5; RR during Wave 1: 5.1, 4.9 to 5.3); a similar pattern was seen for learning disabilities (RR prepandemic: 3.6, 3.4 to 3.5; during Wave 1: 4.8, 4.4 to 5.3), for black or South Asian ethnicity compared to white, and for London compared to other regions. Relative risks for morbidities were stable in multiple sensitivity analyses. However, a limitation of the study is that we cannot assume that the risks observed during Wave 1 would apply to other waves due to changes in population behaviour, virus transmission, and risk perception.ConclusionsThe first wave of the UK COVID-19 pandemic appeared to amplify baseline mortality risk to approximately the same relative degree for most population subgroups. However, disproportionate increases in mortality were seen for those with dementia, learning disabilities, non-white ethnicity, or living in London.

Helen Strongman and colleagues investigate the health and demographic factors associated with excess mortality during, as compared to before, the COVID-19 pandemic.     

Sperm competition and the evolution of sperm design in mammals

Background  

The influence of sperm competition upon sperm size has been a controversial issue during the last 20 years which remains unresolved for mammals. The hypothesis that, when ejaculates compete with rival males, an increase in sperm size would make sperm more competitive because it would increase sperm swimming speed, has generated contradictory results from both theoretical and empirical studies. In addition, the debate has extended to which sperm components should increase in size: the midpiece to accommodate more mitochondria and produce more energy to fuel motility, or the principal piece to generate greater propulsion forces.     

Purification and partial characterization of a toxin produced by Ganoderma lucidum,the coconut Ganoderma disease pathogen

Abstract

An extracellular, hydrophilic, thermostable phytotoxin was purified to homogeneity from culture fluids of Ganoderma lucidum. The phytotoxin was purified by solvent extraction, gel filtration on Sephadex G-75. Toxicity was evaluated with detached leaf sheath and electrolyte leakage bioassays. Purified phytotoxin induced visible symptoms of the disease, when applied to coconut leaves, fronds and roots even at a low concentration. The toxin is a glycoprotein with carbohydrate as the major component. The importance of the carbohydrate moiety for toxic activity was indicated by inactivation of toxic compounds after periodate oxidation. The toxin caused lesions on a number of other monocots and dicots and proved to be non-host specific.     

Two-step aminoacylation of tRNA without channeling in Archaea

Catalysis of sequential reactions is often envisaged to occur by channeling of substrate between enzyme active sites without release into bulk solvent. However, while there are compelling physiological rationales for direct substrate transfer, proper experimental support for the hypothesis is often lacking, particularly for metabolic pathways involving RNA. Here, we apply transient kinetics approaches developed to study channeling in bienzyme complexes to an archaeal protein synthesis pathway featuring the misaminoacylated tRNA intermediate Glu-tRNA^Gln. Experimental and computational elucidation of a kinetic and thermodynamic framework for two-step cognate Gln-tRNA^Gln synthesis demonstrates that the misacylating aminoacyl-tRNA synthetase (GluRS^ND) and the tRNA-dependent amidotransferase (GatDE) function sequentially without channeling. Instead, rapid processing of the misacylated tRNA intermediate by GatDE and preferential elongation factor binding to the cognate Gln-tRNA^Gln together permit accurate protein synthesis without formation of a binary protein-protein complex between GluRS^ND and GatDE. These findings establish an alternate paradigm for protein quality control via two-step pathways for cognate aminoacyl-tRNA formation.