Influence of blood meal on the responsiveness of olfactory receptor neurons in antennal sensilla trichodea of the yellow fever mosquito, Aedes aegypti

In female Aedes aegypti L. mosquitoes, a blood meal induces physiological and behavioral changes. Previous studies have shown that olfactory receptor neurons (ORNs) housed in grooved peg sensilla on the antennae of Ae. aegypti down-regulate their sensitivity to lactic acid, a key component driving host-seeking behavior, which correlates with observed changes in the host-seeking behavior of this species. In the present study, we performed electrophysiological recordings from the most abundant antennal sensillum type, sensilla trichodea. Our results indicate that the response spectra of ORNs contained within most trichoid sensilla do not change in response to blood feeding. However, we observe an increase in sensitivity to primarily indole and phenolic compounds in neurons housed within four of the five functional types of short blunt tipped II trichoid sensilla, both at 24 and 72 h post-blood feeding, which was more pronounced at 24 h than 72 h. Furthermore, sensitivity to undecanone, acetic acid and propionic acid was observed to increase 72 h post-blood meal. Considering the timing of these changes, we believe that these neurons may be involved in driving the orientation behavior of female mosquitoes to oviposition sites, which are known to release these compounds

‘As long as it comes off as a cigarette ad, not a civil rights message’:Gender, inequality and the commercial determinants of health

Scholarship on the commercial determinants of health (CDoH) has sought to understand the multiple ways corporate policies, practices and products affect population health. At the same time, gender is recognised as a key determinant of health and an important axis of health inequalities. To date, there has been limited attention paid to the ways in which the CDoH engage with and impact on gender inequalities and health. This review seeks to address this gap by examining evidence on the practices and strategies of two industries-tobacco and alcohol-and their interaction with gender, with a particular focus on women. We first describe the practices by which these industries engage with women in their marketing and corporate social responsibility activities, reinforcing problematic gender norms and stereotypes that harm women and girls. We then examine how tobacco and alcohol companies contribute to gender inequalities through a range of strategies intended to protect their market freedoms and privileged position in society. By reinforcing gender inequalities at multiple levels, CDoH undermine the health of women and girls and exacerbate global health inequalities.While this research received no specific funding, both authors are members of the SPECTRUM Consortium (Shaping Public Health Policies to Reduce Inequalities and Harm) funded by the UK Prevention Research Partnership (MR/S037519/1)

Modulation of odour-guided behaviour in mosquitoes

Mosquitoes are emerging as model systems with which to study innate behaviours through neuroethology and functional genomics. Decades of work on these disease vectors have provided a solid behavioural framework describing the distinct repertoire of predominantly odour-mediated behaviours of female mosquitoes, and their dependence on life stage (intrinsic factors) and environmental cues (extrinsic factors). The purpose of this review is to provide an overview of how intrinsic factors, including adult maturation, age, nutritional status, and infection, affect the attraction to plants and feeding on plant fluids, host seeking, blood feeding, supplemental feeding behaviours, pre-oviposition behaviour, and oviposition in female mosquitoes. With the technological advancements in the recent two decades, we have gained a better understanding of which volatile organic compounds are used by mosquitoes to recognise and discriminate among various fitness-enhancing resources, and characterised their neural and molecular correlates. In this review, we present the state of the art of the peripheral olfactory system as described by the neural physiology, functional genomics, and genetics underlying the demonstrated changes in the behavioural repertoire in female mosquitoes. The review is meant as a summary introduction to the current conceptual thinking in the field

Molecular basis for odorant receptor tuning: a short C-terminal sequence is necessary and sufficient for selectivity of mosquito Or8

A birth-and-death evolutionary model for odorant receptor gene repertoires presumes the creation of repertoires with the capacity for high-level diversity and rapid ligand specificity change. This changes the recognised odour space, directly affecting fitnessrelated behaviours and ultimately affecting adaptation to new environments and resources. The proximate molecular mechanisms underlying the tuning of odorant receptor repertoires, and thus peripheral olfaction, are unclear. In the present study, we report a concrete example of this model of odorant receptor evolution leading to rapid changes in receptor tuning that leave the peripheral neuronal circuitry intact. We identified a conserved odorant receptor gene in mosquitoes, Or8, which in Culex quinquefasciatus underwent a duplication and inversion event. The paralogues differ in only minor structural changes manifesting at the C-terminus. We assessed the specificity of the paralogous odorant receptors and receptor neurones. We found that the functional tuning of the receptor was indeed reflected in minor differences in amino acid structure. Specifically, we found that enantiomeric specificity of these mosquito Or8 paralogues relies on eight Cterminal amino acids encoded in the final exon of the gene; thus, the birth of a paralogous odorant receptor can change the tuning of the peripheral olfactory system

Atomic oxygen interaction with solar array blankets at protective coating defect sites

Atomic oxygen in the low-Earth-orbital environment oxidizes SiOx protected polyimide Kapton solar array blankets at sites which are not protected such as pin windows or scratches in the protective coatings. The magnitude and shape of the atomic oxygen undercutting which occurs at these sites is dependent upon the exposure environment details such as arrival direction and reaction probability. The geometry of atomic oxygen undercutting at defect sites exposed to atomic oxygen in plasma asher was used to develop a Monte Carlo model to simulate atomic oxygen erosion processes at defect sites in protected Kapton. Comparisons of Monte Carlo predictions and experimental results are presented for plasma asher atomic oxygen exposures for large and small defects as well as for protective coatings on one or both sides of Kapton. The model is used to predict in-space exposure results at defect sites for both directed and sweeping atomic oxygen exposure. A comparison of surface textures predicted by the Monte Carlo model and those experimentally observed from both directed space ram and laboratory plasma asher atomic oxygen exposure indicate substantial agreement

Adenosine triphosphate overrides the aversive effect of antifeedants and toxicants: a model alternative phagostimulant for sugar-based vector control tools

BackgroundSugar, when used as the phagostimulant in attractive toxic bait control tools, limits the efficacy and selectivity of this technology. Thus, more potent and selective phagostimulants than sugar are required to improve this technology. The potency of adenosine triphosphate (ATP) as an alternative model phagostimulant was assessed to determine its capacity to override the aversive effects of select antifeedants and toxicants. How ATP and sucrose modulate the rate of toxicity in the yellow fever mosquito Aedes aegypti was also examined.MethodsA no-choice feeding assay was used to investigate the phagostimulatory ability of ATP to override the aversive effects of structurally divergent antifeedant and toxicant compounds, and to modulate the rate of toxicity over 24 h. Binary combinations of antifeedant and toxicant compounds, at various concentrations, were similarly assessed for enhanced lethal potency. In comparison, no-choice open access and cotton wick feeding assays were used to determine the phagostimulatory role of sucrose in the ingestion of boric acid-laced diets. Dissections of the guts were performed to determine the diet destination as dependant on the phagostimulant.ResultsATP is a potent phagostimulant that dose dependently overrides aversion to antifeedant and toxicant tastants. Feeding on antifeedant- or toxicant-laced diets that was induced by ATP selectively resulted in rapid knockdown (nicotine, lobeline and caffeine) or death (boric acid and propylene glycol), with a combination of the two lethal compounds inducing a synergistic effect at lower concentrations. ATP- and sucrose-induced feeding predominantly directed the antifeedant- or toxicant-laced meals to the midgut and the crop, respectively.ConclusionsATP is an efficacious alternative model phagostimulant to sucrose that overrides the aversive effects of antifeedants and toxicants, resulting in rapid toxic effects. Furthermore, this study demonstrates that variation in the rate of toxicity between ATP- and sugar-induced feeding is at least partly regulated by the differential feeding response, volume imbibed and the destination of the meals. Additional research is needed to identify structurally related, stable analogues of ATP due to the ephemeral nature of this molecule. For future applications, the workflow presented in this study may be used to evaluate such analogues for their suitability for use in attractive bait stations designed to target a broad range of haematophagous arthropods and prevent off-target species' feeding

Math Learning Digital Choice Board

This choice board invites students to: Make a stop motion animation to teach a math concept. Make, fly, and measure your own paper airplane designs. Evaluate how math is used in digital games. And explore more math learning topics and learn about math and writing connections at our Bookcase for Young Writers.https://scholarworks.umass.edu/tecs_ed_materials/1027/thumbnail.jp

Effect of non-human hosts on the human biting rate of primary and secondary malaria vectors in Tanzania

Background Malaria vectors vary in feeding preference depending on their innate behaviour, host availability and abundance. Host preference and human biting rate in malaria vectors are key factors in establishing zooprophylaxis and zoopotentiation. This study aimed at assessing the impact of non-human hosts in close proximity to humans on the human biting rate of primary and secondary malaria vectors, with varying host preferences.Methods The effect of the presence of non-human hosts in close proximity to the human host on the mean catches per person per night, as a proxy for mosquito biting rate, was measured using mosquito-electrocuting traps (METs), in Sagamaganga, Kilombero Valley, Tanzania. Two experiments were designed: (1) a human versus a calf, each enclosed in a MET, and (2) a human surrounded by three calves versus a human alone, with each human volunteer enclosed individually in a MET spaced 10 m apart. Each experiment was conducted on alternate days and lasted for 36 nights per experiment. During each experiment, the positions of hosts were exchanged daily (except the human in experiment 2). All anopheline mosquitoes caught were assayed for Plasmodium sporozoites using enzyme-linked immunosorbent assay.Results A total of 20,574 mosquitoes were captured and identified during the study, of which 3608 were anophelines (84.4% primary and 15.6% secondary malaria vectors) and 17,146 were culicines. In experiment 1, the primary malaria vector, Anopheles arabiensis, along with Culex spp. demonstrated a preference for cattle, while the primary vectors, Anopheles funestus, preferred humans. In experiment 2, both primary vectors, An. arabiensis and An. funestus, as well as the secondary vector Anopheles rivolurum, demonstrated behaviours amenable to zooprophylaxis, whereas Culex spp. increased their attraction to humans in the presence of nearby cattle. All anopheline mosquitoes tested negative for sporozoites.Conclusions The findings of this study provide support for the zooprophylaxis model for malaria vectors present in the Kilombero Valley, and for the zoopotentiation model, as it pertains to the Culex spp. in the region. However, the factors regulating zooprophylaxis and zoopotentiation are complex, with different species-dependent mechanisms regulating these behaviours, that need to be considered when designing integrated vector management programmes

Public Record Under Threat: News and the Archive in the Age of Digital Distribution

The evolution of the internet has created a vast storehouse of information, both current and historical, and all at the fingertips of the general public as well as journalists. But as we find ourselves apparently saturated by information and overwhelmed by its sources, we face a potential crisis of preservation as we seek—and often fail—to archive all manner of digital content. News organizations have been slow to recognize and respond to the preservation challenges presented by digital technology. As a result, newsroom discussions about preservation and archiving are few and far between. However, professionals such as librarians, archivists and technologists outside of news industry are having these conversations, about retaining both conventional news content and online news, as well as about the problems inherent in trying to preserve the multitude of digital and data projects. This shift from paper (or film) to digital record prompted the title of the conference that is the focus of this report: “Public Record Under Threat: News and the Archive in the Age of Digital Distribution.” The conference, the fourth and last in this phase of the Tow Center for Digital Journalism’s Platforms & Publishers series, arose from a recognition of the problems this shift has created in the archive.. While archivists and librarians generally agree that preservation of news content is an acute concern that must be addressed quickly, platforms and publishers often express doubt about whether they have anything to contribute to the discussion. Getting this crowd together in the same room—archivists, journalists and technologists—is a first step toward defining the problem, and subsequently mapping out solutions

Knockout of OR39 reveals redundancy in the olfactory pathway regulating the acquisition of host seeking in Anopheles coluzzii

The attraction of anthropophilic mosquitoes to human host cues, such as body odour and carbon dioxide, gradually increases during adult maturation. This acquisition of host-seeking behaviour correlates with age-dependent changes in odorant receptor (OR) transcript abundance and sensitivity of olfactory sensory neurons (OSNs). One OR gene of the human malaria vector, Anopheles coluzzii, AcolOR39, is significantly downregulated in mature females, and a cognate ligand of AcolOR39, sulcatone, a major component of human emanations, mediates the observed behavioural inhibition of newly emerged (teneral) females to human body odour. Knockout of AcolOR39, using CRISPR-Cas9 mutagenesis, selectively abolished sulcatone detection in OSNs, housed in trichoid sensilla. However, knockout of AcolOR39 altered neither the response rate nor the flight behaviour of teneral females in a wind tunnel, indicating the involvement of other genes, and thus a redundancy, in regulating the acquisition of host seeking in mosquitoes