scholarly journals Neuronal Odor Coding in the Larval Sensory Cone of Anopheles coluzzii: Complex Responses from a Simple System

2020 ◽  
Author(s):  
Huahua Sun ◽  
Feng Liu ◽  
Adam Baker ◽  
Laurence J. Zwiebel
Keyword(s):  
Disease Transmission ◽  
Mosquito Control ◽  
Anopheles Coluzzii ◽  
Global Public Health ◽  
Electrophysiological Response ◽  
Anopheles Mosquitoes ◽  
Larval Stages ◽  
Chemical Structures ◽  
Chemical Discrimination ◽  
Response Profiles

AbstractAnopheles mosquitoes are the sole vectors of malaria and other diseases that represent significant threats to global public health. While adult female mosquitoes are responsible for disease transmission, the pre-adult larval stages of the malaria vector Anopheles coluzzii and other mosquitoes rely on a broad spectrum of sensory cues to navigate their aquatic habitats efficiently to avoid predators and search for food. Of these, mosquito larvae rely heavily on volatile chemical signals that directly activate their olfactory apparatus. Because most studies on mosquito olfaction focus on adults, a paucity of attention has been given to the larval olfactory system, in which the peripheral components are associated with the sensory cone of the larval antennae. To address this, we have investigated the electrophysiological response profile of the larval sensory cone in Anopheles mosquitoes. We found that the larval sensory cone is particularly tuned to alcohols, thiazoles and heterocyclics. Furthermore, these responses can be assigned to discrete groups of sensory cone neurons with distinctive, dose-dependent odorant-response profiles that also provide larvae with the ability to discriminate among compounds with similar chemical structures. A correlation analysis was conducted to determine the relationship between specific larval chemosensory receptors and the response profiles of sensory cone neuron groups. These studies reveal that the larval sensory cone is a highly sophisticated organ that is sensitive to a broad range of compounds and is capable of a remarkable degree of chemical discrimination. Taken together, this study presents critical insights into olfactory coding processes in An. coluzzii larvae that further our understanding of larval chemical ecology and will contribute to the development of novel larval-based strategies and tools for mosquito control and the reduction of vector-borne disease transmission.

scholarly journals Plasmodium PIMMS43 is required for ookinete evasion of the mosquito complement-like response and sporogonic development in the oocyst

2019 ◽  
Author(s):  
Chiamaka V. Ukegbu ◽  
Maria Giorgalli ◽  
Sofia Tapanelli ◽  
Luisa D.P. Rona ◽  
Amie Jaye ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Surface Protein ◽  
Clinical Malaria ◽  
Current Control ◽  
Bed Nets ◽  
Anopheles Coluzzii ◽  
Malaria Parasites ◽  
Target Disease

AbstractMalaria transmission requires Plasmodium parasites to successfully infect a female Anopheles mosquito, surviving a series of robust innate immune responses. Understanding how parasites evade these responses can highlight new ways to block malaria transmission. We show that ookinete and sporozoite surface protein PIMMS43 is required for Plasmodium ookinete evasion of the Anopheles coluzzii complement-like system and for sporogonic development in the oocyst. Disruption of P. berghei PIMMS43 triggers robust complement activation and ookinete elimination upon mosquito midgut traversal. Silencing the complement-like system restores ookinete-to-oocyst transition. Antibodies that bind PIMMS43 interfere with parasite immune evasion when ingested with the infectious blood meal and significantly reduce the prevalence and intensity of infection. PIMMS43 genetic structure across African P. falciparum populations indicates allelic adaptation to sympatric vector populations. These data significantly add to our understanding of mosquito-parasite interactions and identify PIMMS43 as a target of interventions aiming at malaria transmission blocking.Author summaryMalaria is a devastating disease transmitted among humans through mosquito bites. Mosquito control has significantly reduced clinical malaria cases and deaths in the last decades. However, as mosquito resistance to insecticides is becoming widespread impacting on current control tools, such as insecticide impregnated bed nets and indoor spraying, new interventions are urgently needed, especially those that target disease transmission. Here, we characterize a protein found on the surface of malaria parasites, which serves to evade the mosquito immune system ensuring disease transmission. Neutralization of PIMMS43, either by eliminating it from the parasite genome or by pre-incubating parasites with antibodies that bind to the protein, is shown to inhibit mosquito infection by malaria parasites. Differences in PIMMS43 detected between malaria parasite populations sampled across Africa suggest that these populations have adapted for transmission by different mosquito vectors that are also differentially distributed across the continent. We conclude that interventions targeting PIMMS43 could block malaria parasites inside mosquitoes before they can infect humans.

Preparation and Antitubercular Activities of Palindromic Hydrazinecarbothioamides and Carbonothioic Dihydrazides

2019 ◽  
Vol 16 (11) ◽  
pp. 1202-1210 ◽  
Author(s):  
Michael Joseps Hearn ◽  
Gwendolyn Towers ◽  
Michael Henry Cynamon
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Virulent Strain ◽  
Chemotherapeutic Agents ◽  
Disc Diffusion ◽  
Global Public Health ◽  
Health Crisis ◽  
Chemical Structures ◽  
Public Health Crisis ◽  
Zones Of Inhibition ◽  
Diffusion Assay

Background:With approximately one-third of the world’s population infected, tuberculosis continues to be a global public health crisis. The rise of strains that are unusually virulent or highly resistant to current drugs is a cause of special concern, prompting research into new classes of compounds, as well as the re-evaluation of known chemotherapeutic agents.Objectives:The antimycobacterial activities associated with some recently-reported thiocarbonyl compounds kindled our interest in the synthesis of substituted hydrazinecarbothioamides (3) and carbonothioic dihydrazides (4), with the aim of investigating their potential in antitubercular drug design and discovery.Methods:In the present study, the title compounds 3 and 4 were prepared by the condensation of hydrazines with isothiocyanates in reactions readily controlled by stoichiometry, temperature and solvent. The compounds were assessed against Mycobacterium bovis BCG in Kirby-Bauer disc diffusion, and minimum inhibitory concentrations were determined against the virulent strain M. tuberculosis Erdman.Results:The chemical structures of these thermally stable compounds were determined by IR, 1HNMR, 13C-NMR, high-resolution mass spectrometry and elemental analysis. In the Kirby-Bauer disc diffusion assay, some of the compounds showed substantial diameters of inhibition against BCG. In some cases, the zones of inhibition were so large that no growth at all was observed on the assay plates. Against M. tuberculosis Erdman, several of the compounds showed significant activities. Compound 3h was the most active, demonstrating a minimum inhibitory concentration of 0.5 µg/mL.Conclusion:We found that the title compounds may be prepared conveniently in excellent purity and good yields. They are readily identified on the basis of their characteristic spectra. Some members of this class showed significant activities against mycobacteria. We conclude that further work will be warranted in exploring the antitubercular properties of these compounds.

Investigating Male Aedes aegypti (Diptera: Culicidae) Attraction to Different Oviposition Containers Using Various Configurations of the Sound Gravid Aedes Trap

2019 ◽  
Vol 57 (3) ◽  
pp. 957-961
Author(s):  
Kyran M Staunton ◽  
Barukh B Rohde ◽  
Michael Townsend ◽  
Jianyi Liu ◽  
Mark Desnoyer ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Zika Virus ◽  
Disease Transmission ◽  
Urban Landscape ◽  
Mosquito Control ◽  
Transmission Risk ◽  
Northern Australia ◽  
Control Programs ◽  
Male Dispersal ◽  
Olfactory Attractant

Abstract Aedes aegypti (Linnaeus), the primary vectors of the arboviruses dengue virus and Zika virus, continue to expand their global distributions. In efforts to better control such species, several mosquito control programs are investigating the efficacy of rearing and releasing millions of altered male Aedes throughout landscapes to reduce populations and disease transmission risk. Unfortunately, little is known about Ae. aegypti, especially male, dispersal behaviors within urban habitats. We deployed Sound-producing Gravid Aedes Traps (SGATs) in Cairns, northern Australia, to investigate male Ae. aegypti attraction to various oviposition container configurations. The traps were arranged to include: 1) water only, 2) organically infused water, 3) infused water and L3 larvae, 4) infused water and a human-scented lure, and lastly 5) no water or olfactory attractant (dry). Our data suggest that males were more attracted to SGATs representing active larval sites than potential larval sites, but were equally attracted to dry SGATs relative to those containing water and/or infusion. Additionally, we found that female Ae. aegypti were equally attracted to wet SGATs, with or without infusion, but not dry ones. These results suggest that male Ae. aegypti within northern Australia are more attracted to active larval sites and equally attracted to dry containers as wet or infused ones. Additionally, female Ae. aegypti are unlikely to enter dry containers. Such findings contribute to our understanding of potentially attractive features for local and released Ae. aegypti throughout the northern Australian urban landscape.

scholarly journals Vaccinating Adolescents and Children Significantly Reduces COVID-19 Morbidity and Mortality across All Ages: A Popula-Tion-Based Modeling Study Using the UK as an Example

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1180
Author(s):  
Tinevimbo Shiri ◽  
Marc Evans ◽  
Carla A. Talarico ◽  
Angharad R. Morgan ◽  
Maaz Mussad ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Age Groups ◽  
Population Level ◽  
Vital Role ◽  
Morbidity And Mortality ◽  
Transmission Model ◽  
Base Case ◽  
Global Public Health ◽  
The Uk ◽  
The Impact

Debate persists around the risk–benefit balance of vaccinating adolescents and children against COVID-19. Central to this debate is quantifying the contribution of adolescents and children to the transmission of SARS-CoV-2, and the potential impact of vaccinating these age groups. In this study, we present a novel SEIR mathematical disease transmission model that quantifies the impact of different vaccination strategies on population-level SARS-CoV-2 infections and clinical outcomes. The model employs both age- and time-dependent social mixing patterns to capture the impact of changes in restrictions. The model was used to assess the impact of vaccinating adolescents and children on the natural history of the COVID-19 pandemic across all age groups, using the UK as an example. The base case model demonstrates significant increases in COVID-19 disease burden in the UK following a relaxation of restrictions, if vaccines are limited to those ≥18 years and vulnerable adolescents (≥12 years). Including adolescents and children in the vaccination program could reduce overall COVID-related mortality by 57%, and reduce cases of long COVID by 75%. This study demonstrates that vaccinating adolescents and children has the potential to play a vital role in reducing SARS-CoV-2 infections, and subsequent COVID-19 morbidity and mortality, across all ages. Our results have major global public health implications and provide valuable information to inform a potential pandemic exit strategy.

scholarly journals Evaluation of the Larvicidal Potential of the Leaf Extracts of Hyptis suaveolens Poit against Anopheles Mosquitoes

2018 ◽  
pp. 1-9
Author(s):  
Amaka, John I. ◽  
Attah, D. Daniel ◽  
Obisike, Victor U. ◽  
Benedict, Aboje G.
Keyword(s):  
Mosquito Control ◽  
Larval Instar ◽  
Test Organism ◽  
Phytochemical Screening ◽  
Leaf Extracts ◽  
Anopheles Mosquitoes ◽  
Lc50 Value ◽  
Hyptis Suaveolens ◽  
Test Organisms ◽  
Layer Chromatography

This study evaluated the larvicidal potential of the ethanolic and aqueous leaf extracts of Hyptis suaveolens Poit on the 4th larval instar of laboratory-reared Anopheles spp at varying concentrations of 0.1ml, 0.2ml, 0.3ml, 0.4ml and 0.5ml for specified periods of 24hrs, 48hrs and 72hrs. Qualitative phytochemical screening of the leaf extracts identified bioactive components like alkaloid, saponin, phenol, anthraquinone and flavonoid. The LC50 and LC90 values obtained indicate that the ethanolic leaf extracts of Hyptis suaveolens Poit had the greatest toxicity on the test organisms within 24hrs of exposure at median LC50 value of 0.485ml compared to the LC50 value of 0.625ml by its aqueous extract. The relative median potency estimates indicate that within 24 hrs, the ethanolic Hyptis suaveolens Poit was 0.161 times more potent on the test organism than aqueous Hyptis suaveolens Poit. The result of this research, therefore, underscores the efficacy of Hyptis suaveolens Poit as an eco-friendly alternative in Anopheles mosquito control. It is, therefore, recommended that quantitative phytochemical screening, application of column chromatography as well as thin layer chromatography be carried out on the extracts to isolate and purify toxic phytochemicals with larvicidal potentiality.

scholarly journals Effects of seasonality and land use on the abundance and distribution of mosquitoes on St. Kitts, West Indies

2020 ◽  
Author(s):  
Matthew J. Valentine ◽  
Brenda Ciraola ◽  
Gregory R. Jacobs ◽  
Charlie Arnot ◽  
Patrick J. Kelly ◽  
...  
Keyword(s):  
Land Cover ◽  
Disease Transmission ◽  
Negative Binomial ◽  
Mosquito Control ◽  
Mosquito Species ◽  
Negative Binomial Regression ◽  
Common Species ◽  
Negative Binomial Regression Model ◽  
Local Data ◽  
Land Covers

AbstractBackgroundHigh quality mosquito surveys that collect fine resolution local data on mosquito species’ abundances provide baseline data to help us understand potential host-pathogen-mosquito relationships, accurately predict disease transmission, and target mosquito control efforts in areas at risk of mosquito borne diseases.MethodsAs part of an investigation into arboviral sylvatic cycles on the Caribbean island of St. Kitts, we carried out an island wide mosquito survey from November 2017 to March 2019. Using Biogents Sentinel 2 and miniature CDC light traps that were set monthly and run for 48 hour intervals, we collected mosquitoes from a total of 30 sites distributed across the five common land covers on the island (agricultural, mangrove, rainforest, scrub, and urban). We developed a mixed effects negative binomial regression model to predict the effects of land cover, seasonality, and precipitation on observed counts of the most abundant mosquito species we found.ResultsWe captured 10 of the 14 mosquito species reported on the island, the four most abundant being Aedes taeniorhynchus, Culex quinquefasciatus, Aedes aegpyti, and Deinocerites magnus. Sampling in the mangroves yielded the most mosquitoes, with Ae. taeniorhynchus, Cx. quinquefasciatus, and De. magnus predominating. Aedes aegypti was recovered primarily from urban and agricultural habitats, but also at lower frequency in other land covers. Psorophora pygmaea and Toxorhynchites guadeloupensis were only captured in scrub habitat. Capture rates in rainforests were low. Our models indicated the relative abundance of the four most common species varied seasonally and with land cover. They also suggested that the extent to which monthly average precipitation influenced counts varied according to species.ConclusionsThis study demonstrates there is high seasonality in mosquito abundances and that land cover influenced the distribution and abundance of mosquito species on St. Kitts. Further, human-adapted mosquito species (e.g. Ae. aegypti and Cx. quinquefasciatus) that are known vectors for many human relevant pathogens are the most wide-spread (across land covers) and the least responsive to seasonal variation in precipitation.

scholarly journals Exploring the Role of Innate Lymphocytes in the Immune System of Bats and Virus-Host Interactions

Viruses ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 150
Author(s):  
Wan Rong Sia ◽  
Yichao Zheng ◽  
Fei Han ◽  
Shiwei Chen ◽  
Shaohua Ma ◽  
...  
Keyword(s):  
Immune System ◽  
Disease Transmission ◽  
Viral Infections ◽  
Current Knowledge ◽  
Future Research ◽  
Global Public Health ◽  
Immune Systems ◽  
Adaptive Immune ◽  
Adaptive Immune Cells ◽  
Innate Lymphocytes

Bats are reservoirs of a large number of viruses of global public health significance, including the ancestral virus for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the causative agent of coronavirus disease 2019 (COVID-19). Although bats are natural carriers of multiple pathogenic viruses, they rarely display signs of disease. Recent insights suggest that bats have a more balanced host defense and tolerance system to viral infections that may be linked to the evolutionary adaptation to powered flight. Therefore, a deeper understanding of bat immune system may provide intervention strategies to prevent zoonotic disease transmission and to identify new therapeutic targets. Similar to other eutherian mammals, bats have both innate and adaptive immune systems that have evolved to detect and respond to invading pathogens. Bridging these two systems are innate lymphocytes, which are highly abundant within circulation and barrier tissues. These cells share the characteristics of both innate and adaptive immune cells and are poised to mount rapid effector responses. They are ideally suited as the first line of defense against early stages of viral infections. Here, we will focus on the current knowledge of innate lymphocytes in bats, their function, and their potential role in host–pathogen interactions. Moreover, given that studies into bat immune systems are often hindered by a lack of bat-specific research tools, we will discuss strategies that may aid future research in bat immunity, including the potential use of organoid models to delineate the interplay between innate lymphocytes, bat viruses, and host tolerance.

scholarly journals Human infectious disease burdens decrease with urbanization but not with biodiversity

2017 ◽  
Vol 372 (1722) ◽  
pp. 20160122 ◽  
Author(s):  
Chelsea L. Wood ◽  
Alex McInturff ◽  
Hillary S. Young ◽  
DoHyung Kim ◽  
Kevin D. Lafferty
Keyword(s):  
Infectious Disease ◽  
Infectious Diseases ◽  
Disease Transmission ◽  
Scientific Evidence ◽  
Dilution Effect ◽  
Policy Implications ◽  
Global Public Health ◽  
Country Level ◽  
Life Years ◽  
Over Time

Infectious disease burdens vary from country to country and year to year due to ecological and economic drivers. Recently, Murray et al. (Murray CJ et al . 2012 Lancet 380 , 2197–2223. ( doi:10.1016/S0140-6736(12)61689-4 )) estimated country-level morbidity and mortality associated with a variety of factors, including infectious diseases, for the years 1990 and 2010. Unlike other databases that report disease prevalence or count outbreaks per country, Murray et al. report health impacts in per-person disability-adjusted life years (DALYs), allowing comparison across diseases with lethal and sublethal health effects. We investigated the spatial and temporal relationships between DALYs lost to infectious disease and potential demographic, economic, environmental and biotic drivers, for the 60 intermediate-sized countries where data were available and comparable. Most drivers had unique associations with each disease. For example, temperature was positively associated with some diseases and negatively associated with others, perhaps due to differences in disease agent thermal optima, transmission modes and host species identities. Biodiverse countries tended to have high disease burdens, consistent with the expectation that high diversity of potential hosts should support high disease transmission. Contrary to the dilution effect hypothesis, increases in biodiversity over time were not correlated with improvements in human health, and increases in forestation over time were actually associated with increased disease burden. Urbanization and wealth were associated with lower burdens for many diseases, a pattern that could arise from increased access to sanitation and healthcare in cities and increased investment in healthcare. The importance of urbanization and wealth helps to explain why most infectious diseases have become less burdensome over the past three decades, and points to possible levers for further progress in improving global public health. This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications’.

Electrophysiological and experimental-behavioral approaches to the study of intra-sentential code-switching

2017 ◽  
Vol 8 (1) ◽  
pp. 134-161 ◽  
Author(s):  
Janet G. van Hell ◽  
Carla B. Fernandez ◽  
Gerrit Jan Kootstra ◽  
Kaitlyn A. Litcofsky ◽  
Caitlin Y. Ting
Keyword(s):  
Language Processing ◽  
Empirical Studies ◽  
Code Switching ◽  
Cognitive Mechanisms ◽  
Brain Potentials ◽  
Electrophysiological Response ◽  
Time Frequency ◽  
Behavioral Techniques ◽  
Approaches To Study ◽  
Response Profiles

Abstract A hallmark of bilingual language processing is intra-sentential code-switching. An emergent body of research seeks to understand the intricate neural and cognitive mechanisms that underlie this seemingly effortless skill. In this paper, we discuss electrophysiological and experimental-behavioral research approaches that have been used to study intra-sentential code-switching, and illustrate the use of these techniques by discussing a select number of empirical studies. More specifically, we discuss electrophysiological approaches that are used to study the comprehension of visually and auditorily presented code-switched sentences, including the Event-Related brain Potentials (ERPs) method, time-frequency analysis, and approaches to study inter-individual variation in electrophysiological response profiles. This is followed by a discussion of experimental-behavioral techniques to study the comprehension and production of code-switched sentences, including self-paced reading, shadowing, and confederate scripting.

scholarly journals PERUBAHAN HISTOPATOLOGI MIDGUT LARVA An. vagus (DIPTERA : CULICIDAE) AKIBAT PAPARAN EKSTRAK BIJI PINANG (Areca catechu L).

2018 ◽  
Vol 46 (4) ◽  
Author(s):  
Majematang Mading
Keyword(s):  
Mosquito Control ◽  
Histopathological Examination ◽  
Control Program ◽  
Seed Extract ◽  
Control Group ◽  
Control Group Design ◽  
Larval Midgut ◽  
Anopheles Mosquitoes ◽  
Ultrasonic Methods ◽  
Areca Catechu

Anopheles mosquitoes is main vector of malaria and filariasis. The use of bioinsecticide is an alternative way to reduce the negative impacts of synthetic insecticide. Areca catechu L. seeds contain secondary metabolites that have bioinsectisidal effects. The aim of this study was to analyze the effects of A.catechu L. seed extract on An. vagus larvae midgut. This study was a laboratory experimental research that designed as post test only control group design. A.catechu L. seed from Southwest Sumba Regency was extracted using ultrasonic methods. Larvae used in this study were Anopheles vagus instar III or early IV that devided into seven groups of the extract concetration (500; 1250; 2000; 2750; 3500; 4250 and 5000 ppm) and control group to find out the toxicity of the extract. Each group consists of twenty five larvae. The histopathology of larval midgut was stained with Hematoxyllin-Eosin and observed using light microscopy 24 hours after exposure. Histopathological examination of larval midgut showed the mild, moderate and severe damages on larval midgut after 24 hours exposure. Areca catechu L. seed extract can lead to changes in damage larval midgut. Areca catechu L. seed extract can be recommended to be used effectively as a natural larvicidal mosquito control program.

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