Spatial and sex-specific dissection of the Anopheles gambiae midgut transcriptome

BACKGROUND: The midgut of hematophagous insects, such as disease transmitting mosquitoes, carries out a variety of essential functions that mostly relate to blood feeding. The midgut of the female malaria vector mosquito Anopheles gambiae is a major site of interactions between the parasite and the vector. Distinct compartments and cell types of the midgut tissue carry out specific functions and vector borne pathogens interact and infect different parts of the midgut. RESULTS: A microarray based global gene expression approach was used to compare transcript abundance in the four major female midgut compartments (cardia, anterior, anterior part of posterior and posterior part of posterior midgut) and between the male and female Anopheles gambiae midgut. Major differences between the female and male midgut gene expression relate to digestive processes and immunity. Each compartment has a distinct gene function profile with the posterior midgut expressing digestive enzyme genes and the cardia and anterior midgut expressing high levels of antimicrobial peptide and other immune gene transcripts. Interestingly, the cardia expressed several known anti-Plasmodium factors. A parallel peptidomic analysis of the cardia identified known mosquito antimicrobial peptides as well as several putative short secreted peptides that are likely to represent novel antimicrobial factors. CONCLUSION: The A. gambiae sex specific midgut and female midgut compartment specific transcriptomes correlates with their known functions. The significantly greater functional diversity of the female midgut relate to hematophagy that is associated with digestion and nutrition uptake as well as exposes it to a variety of pathogens, and promotes growth of its endogenous microbial flora. The strikingly high proportion of immunity related factors in the cardia tissue most likely serves the function to increase sterility of ingested sugar and blood. A detailed characterization of the functional specificities of the female mosquito midgut and its various compartments can greatly contribute to our understanding of its role in disease transmission and generate the necessary tools for the development of malaria control strategies

Genome-wide transcriptomic profiling of Anopheles gambiae hemocytes reveals pathogen-specific signatures upon bacterial challenge and Plasmodium berghei infection

<p>Abstract</p> <p>Background</p> <p>The mosquito <it>Anopheles gambiae </it>is a major vector of human malaria. Increasing evidence indicates that blood cells (hemocytes) comprise an essential arm of the mosquito innate immune response against both bacteria and malaria parasites. To further characterize the role of hemocytes in mosquito immunity, we undertook the first genome-wide transcriptomic analyses of adult female <it>An. gambiae </it>hemocytes following infection by two species of bacteria and a malaria parasite.</p> <p>Results</p> <p>We identified 4047 genes expressed in hemocytes, using <it>An. gambiae </it>genome-wide microarrays. While 279 transcripts were significantly enriched in hemocytes relative to whole adult female mosquitoes, 959 transcripts exhibited immune challenge-related regulation. The global transcriptomic responses of hemocytes to challenge with different species of bacteria and/or different stages of malaria parasite infection revealed discrete, minimally overlapping, pathogen-specific signatures of infection-responsive gene expression; 105 of these represented putative immunity-related genes including anti-<it>Plasmodium </it>factors. Of particular interest was the specific co-regulation of various members of the Imd and JNK immune signaling pathways during malaria parasite invasion of the mosquito midgut epithelium.</p> <p>Conclusion</p> <p>Our genome-wide transcriptomic analysis of adult mosquito hemocytes reveals pathogen-specific signatures of gene regulation and identifies several novel candidate genes for future functional studies.</p

Anopheles gambiae Immune Responses to Human and Rodent Plasmodium Parasite Species

Transmission of malaria is dependent on the successful completion of the Plasmodium lifecycle in the Anopheles vector. Major obstacles are encountered in the midgut tissue, where most parasites are killed by the mosquito's immune system. In the present study, DNA microarray analyses have been used to compare Anopheles gambiae responses to invasion of the midgut epithelium by the ookinete stage of the human pathogen Plasmodium falciparum and the rodent experimental model pathogen P. berghei. Invasion by P. berghei had a more profound impact on the mosquito transcriptome, including a variety of functional gene classes, while P. falciparum elicited a broader immune response at the gene transcript level. Ingestion of human malaria-infected blood lacking invasive ookinetes also induced a variety of immune genes, including several anti-Plasmodium factors. Twelve selected genes were assessed for effect on infection with both parasite species and bacteria using RNAi gene silencing assays, and seven of these genes were found to influence mosquito resistance to both parasite species. An MD2-like receptor, AgMDL1, and an immunolectin, FBN39, showed specificity in regulating only resistance to P. falciparum, while the antimicrobial peptide gambicin and a novel putative short secreted peptide, IRSP5, were more specific for defense against the rodent parasite P. berghei. While all the genes that affected Plasmodium development also influenced mosquito resistance to bacterial infection, four of the antimicrobial genes had no effect on Plasmodium development. Our study shows that the impact of P. falciparum and P. berghei infection on A. gambiae biology at the gene transcript level is quite diverse, and the defense against the two Plasmodium species is mediated by antimicrobial factors with both universal and Plasmodium-species specific activities. Furthermore, our data indicate that the mosquito is capable of sensing infected blood constituents in the absence of invading ookinetes, thereby inducing anti-Plasmodium immune responses

Multi-Object Tracking by Iteratively Associating Detections with Uniform Appearance for Trawl-Based Fishing Bycatch Monitoring

The aim of in-trawl catch monitoring for use in fishing operations is to detect, track and classify fish targets in real-time from video footage. Information gathered could be used to release unwanted bycatch in real-time. However, traditional multi-object tracking (MOT) methods have limitations, as they are developed for tracking vehicles or pedestrians with linear motions and diverse appearances, which are different from the scenarios such as livestock monitoring. Therefore, we propose a novel MOT method, built upon an existing observation-centric tracking algorithm, by adopting a new iterative association step to significantly boost the performance of tracking targets with a uniform appearance. The iterative association module is designed as an extendable component that can be merged into most existing tracking methods. Our method offers improved performance in tracking targets with uniform appearance and outperforms state-of-the-art techniques on our underwater fish datasets as well as the MOT17 dataset, without increasing latency nor sacrificing accuracy as measured by HOTA, MOTA, and IDF1 performance metrics

Site-Specific Integration and Expression of an Anti-Malarial Gene in Transgenic Anopheles gambiae Significantly Reduces Plasmodium Infections

Diseases transmitted by mosquitoes have a devastating impact on global health and this is worsening due to difficulties with existing control measures and climate change. Genetically modified mosquitoes that are refractory to disease transmission are seen as having great potential in the delivery of novel control strategies. Historically the genetic modification of insects has relied upon transposable elements which have many limitations despite their successful use. To circumvent these limitations the Streptomyces phage phiC31 integrase system has been successfully adapted for site-specific transgene integration in insects. Here, we present the first site-specific transformation of Anopheles gambiae, the principal vector of human malaria. Mosquitoes were initially engineered to incorporate the phiC31 targeting site at a defined genomic location. A second phase of genetic modification then achieved site-specific integration of Vida3, a synthetic anti-malarial gene. Expression of Vida3, specifically in the midgut of bloodfed females, offered consistent and significant protection against Plasmodium yoelii nigeriensis, reducing average parasite intensity by 85%. Similar protection was observed against Plasmodium falciparum in some experiments, although protection was inconsistent. In the fight against malaria, it is imperative to establish a broad repertoire of both anti-malarial effector genes and tissue-specific promoters for their expression, enabling those offering maximum effect with minimum fitness cost to be identified. In the future, this technology will allow effective comparisons and informed choices to be made, potentially leading to complete transmission blockade

Measuring affective well-being at work using short-form scales : implications for affective structures and participant instructions

Measuring affective well-being in organizational studies has become increasingly widespread, given its association with key work-performance and other markers of organizational functioning. As such, researchers and policy-makers need to be confident that well-being measures are valid, reliable and robust. To reduce the burden on participants in applied settings, short-form measures of affective well-being are proving popular. However, these scales are seldom validated as standalone, comprehensive measures in their own right. In this article, we used a short-form measure of affective well-being with 10 items: the Daniels five-factor measure of affective well-being (D-FAW). In Study 1, across six applied sample groups (N = 2624), we found that the factor structure of the short-form D-FAW is robust when issued as a standalone measure, and that it should be scored differently depending on the participant instruction used. When participant instructions focus on now or today, then affect is best represented by five discrete emotion factors. When participant instructions focus on the past week, then affect is best represented by two or three mood-based factors. In Study 2 (N = 39), we found good construct convergent validity of short-form D-FAW with another widely used scale (PANAS). Implications for the measurement and structure of affect are discussed

Field-Caught Permethrin-Resistant Anopheles gambiae Overexpress CYP6P3, a P450 That Metabolises Pyrethroids

Insects exposed to pesticides undergo strong natural selection and have developed various adaptive mechanisms to survive. Resistance to pyrethroid insecticides in the malaria vector Anopheles gambiae is receiving increasing attention because it threatens the sustainability of malaria vector control programs in sub-Saharan Africa. An understanding of the molecular mechanisms conferring pyrethroid resistance gives insight into the processes of evolution of adaptive traits and facilitates the development of simple monitoring tools and novel strategies to restore the efficacy of insecticides. For this purpose, it is essential to understand which mechanisms are important in wild mosquitoes. Here, our aim was to identify enzymes that may be important in metabolic resistance to pyrethroids by measuring gene expression for over 250 genes potentially involved in metabolic resistance in phenotyped individuals from a highly resistant, wild A. gambiae population from Ghana. A cytochrome P450, CYP6P3, was significantly overexpressed in the survivors, and we show that the translated enzyme metabolises both alpha-cyano and non–alpha-cyano pyrethroids. This is the first study to demonstrate the capacity of a P450 identified in wild A. gambiae to metabolise insecticides. The findings add to the understanding of the genetic basis of insecticide resistance in wild mosquito populations

Mechanisms underlying the manipulation of reproduction in female Tenebrio molitor by molecules produced by Hymenolepis diminuta

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Using communities of practice to enhance interdisciplinary teaching: lessons from four Australian institutions

We report on the establishment of communities of practice at four Australian institutions and evaluate their effectiveness and durability as a means of building staff and institutional capacity for interdisciplinary teaching. A community of practice approach is a potentially valuable methodology for overcoming dynamics of fragmentation, isolation and competition within universities. The communities we established were anchored by a shared focus on the topic of climate change and they worked collaboratively to build relationships of trust and reciprocity between teachers in a wide range of disciplines. The aim of each community was to improve the teaching of climate change through enabling members to integrate diverse disciplinary perspectives, to teach collaboratively, to promote innovation through exchange and to demonstrate leadership within their institutions. The key factors that made our communities effective and durable are: (1) designation of two leadership roles, activator and facilitator, (2) provision for institutional autonomy in domesticating the model to fit local circumstances and (3) a pragmatic emphasis on opportunities for teaching innovation and leadership within existing administrative structures, teaching programs and workloads. We conclude that suitably designed and resourced communities of practice are a viable means of improving interdisciplinary teaching of complex problems by facilitating both staff development and institutional learning

The interdisciplinary edge: Transforming academic practice and enhancing student learning via interdisciplinary curricula

As we enter the 21st century, the ways that we live, learn, work and interact with people and the environment are changing. Institutions of higher education are questioning how they can transform curricula to prepare graduates for the increasing complexity of the challenges facing humanity. Can degree programs remain static and rooted in single discipline-taught subjects disconnected from real world applications, which inherently span traditional disciplinary boundaries? Students stand to benefit a great deal from learning strategies that are derived from demanding and rigorous curricula based on relevant, real-world problems, which require high levels of self-aware inquiry and problem solving skills. Discussing practical ways to enable academics to collaborate around authentic problems in the face of university structures that make collaboration difficult is an important part of responding to the complex challenges our graduates will face. This special-interest roundtable will centre on the issues associated with achieving interdisciplinary collaboration to facilitate educational change, with discussions of how the Australian tertiary sector should respond to the ongoing single-disciplinary focus that dominates much thinking about higher education. The conveners work across a range of disciplines and institutions and will focus on findings from two ALTC-funded projects that aim to create genuine interdisciplinary curricula to engage and motivate students to enhance learning outcomes