RESUMEN
We report the imminent completion of a set of reference genome assemblies for 16 species of Anopheles mosquitoes. In addition to providing a generally useful resource for comparative genomic analyses, these genome sequences will greatly facilitate exploration of the capacity exhibited by some Anopheline mosquito species to serve as vectors for malaria parasites. A community analysis project will commence soon to perform a thorough comparative genomic investigation of these newly sequenced genomes. Completion of this project via the use of short next-generation sequence reads required innovation in both the bioinformatic and laboratory realms, and the resulting knowledge gained could prove useful for genome sequencing projects targeting other unconventional genomes.
Asunto(s)
Anopheles/genética , Evolución Biológica , Genoma de los Insectos , Malaria/genética , Animales , Secuencia de Bases , Biología Computacional , Genómica , Humanos , Insectos Vectores/genética , Malaria/parasitología , Malaria/transmisión , Análisis de Secuencia de ADNRESUMEN
Reverse genetics in the mosquito Anopheles gambiae by RNAi mediated gene silencing has led in recent years to an advanced understanding of the mosquito immune response against infections with bacteria and malaria parasites. We developed RNAi screens in An. gambiae hemocyte-like cells using a library of double-stranded RNAs targeting 109 genes expressed highly or specifically in mosquito hemocytes to identify novel regulators of the hemocyte immune response. Assays included phagocytosis of bacterial bioparticles, expression of the antimicrobial peptide CEC1, and basal and induced expression of the mosquito complement factor LRIM1. A cell viability screen was also carried out to assess dsRNA cytotoxicity and to identify genes involved in cell growth and survival. Our results identify 22 novel immune regulators, including proteins putatively involved in phagosome assembly and maturation (Ca²âº channel, v-ATPase and cyclin-dependent protein kinase), pattern recognition (fibrinogen-domain lectins and Nimrod), immune modulation (peptidase and serine protease homolog), immune signaling (Eiger and LPS-induced factor), cell adhesion and communication (Laminin B1 and Ninjurin) and immune homeostasis (Lipophorin receptor). The development of robust functional cell-based assays paves the way for genome-wide functional screens to study the mosquito immune response to infections with human pathogens.
Asunto(s)
Anopheles/genética , Proteínas del Sistema Complemento/genética , Silenciador del Gen , Hemocitos/inmunología , Inmunidad Activa/genética , Animales , Anopheles/inmunología , Supervivencia Celular , Células Cultivadas , Proteínas del Sistema Complemento/inmunología , Escherichia coli , Expresión Génica , Estudio de Asociación del Genoma Completo , Hemocitos/citología , Hemocitos/microbiología , Interacciones Huésped-Patógeno , Proteínas de Insectos , Oocistos/citología , Oocistos/inmunología , Fagocitosis/fisiología , Interferencia de ARN , ARN Bicatenario/farmacología , ARN Interferente PequeñoRESUMEN
Malaria remains a devastating disease despite efforts at control and prevention. Extensive studies using mostly rodent infection models reveal that successful Plasmodium parasite transmission by the African mosquito vector Anopheles gambiae depends on finely tuned vector-parasite interactions. Here we investigate the transcriptional response of A. gambiae to geographically related Plasmodium falciparum populations at various infection intensities and different infection stages. These responses are compared with those of mosquitoes infected with the rodent parasite Plasmodium berghei. We demonstrate that mosquito responses are largely dependent on the intensity of infection. A major transcriptional suppression of genes involved in the regulation of midgut homeostasis is detected in low-intensity P. falciparum infections, the most common type of infection in Africa. Importantly, genes transcriptionally induced during these infections tend to be phylogenetically unique to A. gambiae. These data suggest that coadaptation between vectors and parasites may act to minimize the impact of infection on mosquito fitness by selectively suppressing specific functional classes of genes. RNA interference (RNAi)-mediated gene silencing provides initial evidence for important roles of the mosquito G protein-coupled receptors (GPCRs) in controlling infection intensity-dependent antiparasitic responses.
Asunto(s)
Anopheles/inmunología , Anopheles/parasitología , Insectos Vectores/inmunología , Insectos Vectores/parasitología , Plasmodium falciparum/fisiología , Animales , Anopheles/genética , Anopheles/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Interacciones Huésped-Parásitos , Humanos , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Insectos Vectores/genética , Insectos Vectores/metabolismo , Ratones , Filogenia , Plasmodium berghei/fisiologíaRESUMEN
Insect hemocytes mediate important cellular immune responses including phagocytosis and encapsulation and also secrete immune factors such as opsonins, melanization factors, and antimicrobial peptides. However, the molecular composition of these important immune cells has not been elucidated in depth, because of their scarcity in the circulating hemolymph, their adhesion to multiple tissues and the lack of primary culture methods to produce sufficient material for a genome-wide analysis. In this study, we report a genome-wide molecular characterization of circulating hemocytes collected from the hemolymph of adult female Anopheles gambiae mosquitoes--the major mosquito vector of human malaria in subSaharan Africa. Their molecular profile identified 1,485 transcripts with enriched expression in these cells, and many of these genes belong to innate immune gene families. This hemocyte-specific transcriptome is compared to those of Drosophila melanogaster and two other mosquitoes, Aedes aegypti and Armigeres subalbatus. We report the identification of two genes as ubiquitous hemocyte markers and several others as hemocyte subpopulation markers. We assess, via an RNAi screen, the roles in development of Plasmodium berghei of 63 genes expressed in hemocytes and provide a molecular comparison of the transcriptome of these cells during malaria infection.
Asunto(s)
Anopheles/genética , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Genoma de los Insectos/genética , Hemocitos/metabolismo , Aedes/genética , Animales , Drosophila melanogaster/genética , Femenino , Marcadores Genéticos , Malaria , Plasmodium , ARN Mensajero/análisisRESUMEN
Malaria parasites must undergo sexual and sporogonic development in mosquitoes before they can infect their vertebrate hosts. We report the discovery and characterization of MISFIT, the first protein with paternal effect on the development of the rodent malaria parasite Plasmodium berghei in Anopheles mosquitoes. MISFIT is expressed in male gametocytes and localizes to the nuclei of male gametocytes, zygotes and ookinetes. Gene disruption results in mutant ookinetes with reduced genome content, microneme defects and altered transcriptional profiles of putative cell cycle regulators, which yet successfully invade the mosquito midgut. However, developmental arrest ensues during the ookinete transformation to oocysts leading to malaria transmission blockade. Genetic crosses between misfit mutant parasites and parasites that are either male or female gamete deficient reveal a strict requirement for a male misfit allele. MISFIT belongs to the family of formin-like proteins, which are known regulators of the dynamic remodeling of actin and microtubule networks. Our data identify the ookinete-to-oocyst transition as a critical cell cycle checkpoint in Plasmodium development and lead us to hypothesize that MISFIT may be a regulator of cell cycle progression. This study offers a new perspective for understanding the male contribution to malaria parasite development in the mosquito vector.
Asunto(s)
Culicidae/parasitología , Insectos Vectores/parasitología , Plasmodium berghei/crecimiento & desarrollo , Proteínas Protozoarias/genética , Secuencia de Aminoácidos , Animales , Southern Blotting , Femenino , Técnica del Anticuerpo Fluorescente , Expresión Génica , Regulación de la Expresión Génica , Genes Protozoarios/genética , Malaria/transmisión , Masculino , Datos de Secuencia Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , Filogenia , Plasmodium berghei/genética , Plasmodium berghei/metabolismo , Proteínas Protozoarias/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Recognition of peptidoglycan (PGN) is paramount for insect antibacterial defenses. In the fruit fly Drosophila melanogaster, the transmembrane PGN Recognition Protein LC (PGRP-LC) is a receptor of the Imd signaling pathway that is activated after infection with bacteria, mainly Gram-negative (Gram-). Here we demonstrate that bacterial infections of the malaria mosquito Anopheles gambiae are sensed by the orthologous PGRPLC protein which then activates a signaling pathway that involves the Rel/NF-kappaB transcription factor REL2. PGRPLC signaling leads to transcriptional induction of antimicrobial peptides at early stages of hemolymph infections with the Gram-positive (Gram+) bacterium Staphylococcus aureus, but a different signaling pathway might be used in infections with the Gram- bacterium Escherichia coli. The size of mosquito symbiotic bacteria populations and their dramatic proliferation after a bloodmeal, as well as intestinal bacterial infections, are also controlled by PGRPLC signaling. We show that this defense response modulates mosquito infection intensities with malaria parasites, both the rodent model parasite, Plasmodium berghei, and field isolates of the human parasite, Plasmodium falciparum. We propose that the tripartite interaction between mosquito microbial communities, PGRPLC-mediated antibacterial defense and infections with Plasmodium can be exploited in future interventions aiming to control malaria transmission. Molecular analysis and structural modeling provided mechanistic insights for the function of PGRPLC. Alternative splicing of PGRPLC transcripts produces three main isoforms, of which PGRPLC3 appears to have a key role in the resistance to bacteria and modulation of Plasmodium infections. Structural modeling indicates that PGRPLC3 is capable of binding monomeric PGN muropeptides but unable to initiate dimerization with other isoforms. A dual role of this isoform is hypothesized: it sequesters monomeric PGN dampening weak signals and locks other PGRPLC isoforms in binary immunostimulatory complexes further enhancing strong signals.
Asunto(s)
Anopheles/inmunología , Anopheles/microbiología , Infecciones Bacterianas/inmunología , Proteínas Portadoras/inmunología , Plasmodium/inmunología , Empalme Alternativo , Secuencia de Aminoácidos , Animales , Anopheles/metabolismo , Proteínas Portadoras/química , Proteínas Portadoras/genética , ADN Bacteriano/genética , Femenino , Malaria/inmunología , Malaria/transmisión , Datos de Secuencia Molecular , Isoformas de Proteínas/inmunología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/inmunologíaAsunto(s)
Vectores Artrópodos/genética , Genómica/historia , Servicios de Información/historia , Enfermedades Parasitarias/historia , Animales , Animales Modificados Genéticamente/parasitología , Animales Modificados Genéticamente/virología , Arizona , Culicidae/genética , Dengue/transmisión , Genómica/educación , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Internet , Malaria/transmisión , Enfermedades Parasitarias/prevención & control , Enfermedades Parasitarias/transmisiónRESUMEN
C-type lectins (CTLs) are a family of proteins that share a common structural motif, the carbohydrate recognition domain, and may act as receptors in pathogen recognition. Indeed, some vertebrate CTLs, particularly the collectins, are unequivocally implicated in the innate immune response to certain microbes. Although studies in insects and other invertebrates have described CTL activation of effector immune responses in vitro, the contribution of these CTLs to immune defenses in vivo is still poorly understood. Here we report that two CTLs, CTL4 and CTLMA2, which were shown previously to inhibit Plasmodium berghei ookinete melanization in the malaria vector Anopheles gambiae, are transcriptionally induced by bacterial challenge. Using in vivo reverse genetic analysis, we show that both CTLs are required for the clearance of Escherichia coli, but not Staphylococcus aureus, from adult female mosquitoes. Silencing either CTL dramatically reduces mosquito survival to Gram-negative but not to Gram-positive bacterial infections, suggesting a role in defense against Gram-negative bacteria. Furthermore, molecular characterization reveals that both CTLs are secreted into the mosquito hemolymph mainly in the form of a disulfide-linked heterodimer. This association explains the similar roles of these CTLs in bacterial defense as well as in the melanization response to P. berghei ookinetes. Apparently, CTL4 and CTLMA2 serve pleiotropic functions in the innate immune response of A. gambiae.
Asunto(s)
Anopheles/microbiología , Escherichia coli/fisiología , Lectinas Tipo C/fisiología , Animales , Western Blotting , Proliferación Celular , Femenino , Silenciador del Gen/fisiología , Hemolinfa , Lectinas Tipo C/antagonistas & inhibidores , Malaria/transmisión , Mutagénesis Sitio-Dirigida , Plasmodium berghei/fisiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Staphylococcus aureus/fisiologíaRESUMEN
In 2007, the European Research Council (ERC) was launched amid much fanfare with the goal of spearheading Europe's aspirations to become the most dynamic and competitive knowledge-based society in the world. Here, we examine the results of the first two ERC calls for research grants and discuss the latest developments and the challenges that face this unique research council.
Asunto(s)
Investigación , Europa (Continente) , Investigación/economía , Apoyo a la Investigación como Asunto , Sociedades Científicas/economía , Sociedades Científicas/organización & administraciónRESUMEN
Leucine-rich repeat-containing proteins are central to host defense in plants and animals. We show that in the mosquito Anopheles gambiae, two such proteins that antagonize malaria parasite infections, LRIM1 and APL1C, circulate in the hemolymph as a high-molecular-weight complex held together by disulfide bridges. The complex interacts with the complement C3-like protein, TEP1, promoting its cleavage or stabilization and its subsequent localization on the surface of midgut-invading Plasmodium berghei parasites, targeting them for destruction. LRIM1 and APL1C are members of a protein family with orthologs in other disease vector mosquitoes and appear to be important effectors in innate mosquito defenses against human pathogens.
Asunto(s)
Anopheles/inmunología , Anopheles/parasitología , Activación de Complemento , Proteínas de Insectos/metabolismo , Plasmodium berghei/inmunología , Secuencias de Aminoácidos , Animales , Anopheles/genética , Anopheles/metabolismo , Complemento C3/inmunología , Complemento C3/metabolismo , Sistema Digestivo/parasitología , Femenino , Técnicas de Silenciamiento del Gen , Silenciador del Gen , Genes de Insecto , Hemolinfa , Proteínas de Insectos/química , Proteínas de Insectos/genética , Proteínas de Insectos/aislamiento & purificación , Insectos Vectores/genética , Insectos Vectores/inmunología , Insectos Vectores/metabolismo , Insectos Vectores/parasitología , Leucina/química , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , Plasmodium berghei/fisiologíaRESUMEN
VectorBase (http://www.vectorbase.org) is an NIAID-funded Bioinformatic Resource Center focused on invertebrate vectors of human pathogens. VectorBase annotates and curates vector genomes providing a web accessible integrated resource for the research community. Currently, VectorBase contains genome information for three mosquito species: Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus, a body louse Pediculus humanus and a tick species Ixodes scapularis. Since our last report VectorBase has initiated a community annotation system, a microarray and gene expression repository and controlled vocabularies for anatomy and insecticide resistance. We have continued to develop both the software infrastructure and tools for interrogating the stored data.
Asunto(s)
Vectores Artrópodos/genética , Culicidae/genética , Bases de Datos Genéticas , Aedes/genética , Animales , Anopheles/genética , Culex/genética , Culicidae/metabolismo , Perfilación de la Expresión Génica , Genoma de los Insectos , Genómica , Ixodes/genética , Pediculus/genética , Vocabulario ControladoRESUMEN
The European Research Council (ERC) is the first European funding body set up to support investigator-driven frontier research. Its main aim is to stimulate scientific excellence by supporting and encouraging the very best, truly creative scientists, scholars and engineers to be adventurous and take risks in their research. The scientists should go beyond the established frontiers of knowledge and the boundaries of disciplines. Being 'investigator-driven', or 'bottom-up', in nature, the ERC approach allows researchers to identify new opportunities and directions in any field of research. By challenging Europe's brightest minds, the ERC expects to bring about new and unpredictable scientific and technological discoveries-the kind that can form the basis of new industries, markets and broader social innovations of the future. Ultimately, the ERC aims to make the European research base more prepared to respond to the needs of a knowledge-based society and provide Europe with the capabilities in frontier research necessary to meet global challenges.
Asunto(s)
Sociedades Científicas , Europa (Continente) , Apoyo a la Investigación como AsuntoRESUMEN
BACKGROUND: Anopheles innate immunity affects Plasmodium development and is a potential target of innovative malaria control strategies. The extent and distribution of nucleotide diversity in immunity genes might provide insights into the evolutionary forces that condition pathogen-vector interactions. The discovery of polymorphisms is an essential step towards association studies of susceptibility to infection. RESULTS: We sequenced coding fragments of 72 immune related genes in natural populations of Anopheles gambiae and of 37 randomly chosen genes to provide a background measure of genetic diversity across the genome. Mean nucleotide diversity (pi) was 0.0092 in the A. gambiae S form, 0.0076 in the M form and 0.0064 in A. arabiensis. Within each species, no statistically significant differences in mean nucleotide diversity were detected between immune related and non immune related genes. Strong purifying selection was detected in genes of both categories, presumably reflecting strong functional constraints. CONCLUSION: Our results suggest similar patterns and rates of molecular evolution in immune and non-immune genes in A. gambiae. The 3,214 Single Nucleotide Polymorphisms (SNPs) that we identified are the first large set of Anopheles SNPs from fresh, field-collected material and are relevant markers for future phenotype-association studies.
Asunto(s)
Anopheles/genética , Anopheles/inmunología , Evolución Molecular , Inmunidad Innata/genética , Polimorfismo de Nucleótido Simple , Animales , Genes de Insecto , Variación Genética , Humanos , Insectos Vectores/genética , Insectos Vectores/inmunología , Insectos Vectores/parasitología , Malaria Falciparum/prevención & control , Malaria Falciparum/transmisión , Plasmodium falciparum/inmunología , Plasmodium falciparum/patogenicidad , Selección Genética , Especificidad de la EspecieRESUMEN
In much of sub-Saharan Africa, the mosquito Anopheles gambiae is the main vector of the major human malaria parasite, Plasmodium falciparum. Convenient laboratory studies have identified mosquito genes that affect positively or negatively the developmental cycle of the model rodent parasite, P. berghei. Here, we use transcription profiling and reverse genetics to explore whether five disparate mosquito gene regulators of P. berghei development are also pertinent to A. gambiae/P. falciparum interactions in semi-natural conditions, using field isolates of this parasite and geographically related mosquitoes. We detected broadly similar albeit not identical transcriptional responses of these genes to the two parasite species. Gene silencing established that two genes affect similarly both parasites: infections are hindered by the intracellular local activator of actin cytoskeleton dynamics, WASP, but promoted by the hemolymph lipid transporter, ApoII/I. Since P. berghei is not a natural parasite of A. gambiae, these data suggest that the effects of these genes have not been drastically altered by constant interaction and co-evolution of A. gambiae and P. falciparum; this conclusion allowed us to investigate further the mode of action of these two genes in the laboratory model system using a suite of genetic tools and infection assays. We showed that both genes act at the level of midgut invasion during the parasite's developmental transition from ookinete to oocyst. ApoII/I also affects the early stages of oocyst development. These are the first mosquito genes whose significant effects on P. falciparum field isolates have been established by direct experimentation. Importantly, they validate for semi-field human malaria transmission the concept of parasite antagonists and agonists.
Asunto(s)
Anopheles/parasitología , Vectores de Enfermedades , Malaria Falciparum/parasitología , Plasmodium berghei/fisiología , Plasmodium falciparum/fisiología , Animales , Apolipoproteína A-I/genética , Apolipoproteína A-I/metabolismo , Apolipoproteína A-II/genética , Apolipoproteína A-II/metabolismo , Niño , Preescolar , ADN Protozoario/análisis , Sistema Digestivo/parasitología , Femenino , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Silenciador del Gen , Predisposición Genética a la Enfermedad , Interacciones Huésped-Parásitos , Humanos , Malaria Falciparum/sangre , Malaria Falciparum/transmisión , Oocistos/fisiología , Plasmodium berghei/patogenicidad , Plasmodium falciparum/patogenicidad , Polimorfismo de Nucleótido Simple , Transcripción Genética , Proteína del Síndrome de Wiskott-Aldrich/genética , Proteína del Síndrome de Wiskott-Aldrich/metabolismoRESUMEN
For malaria transmission to occur, Plasmodium sporozoites must infect the salivary glands of their mosquito vectors. This study reports that Anopheles gambiae SRPN6 participates in a local salivary gland epithelial response against the rodent malaria parasite, Plasmodium berghei. We showed previously that SRPN6, an immune inducible midgut invasion marker, influences ookinete development. Here we report that SRPN6 is also specifically induced in salivary glands with the onset of sporozoite invasion. The protein is located in the basal region of epithelial cells in proximity to invading sporozoites. Knockdown of SRPN6 during the late phase of sporogony by RNAi has no effect on oocyst rupture but significantly increases the number of sporozoites present in salivary glands. Despite several differences between the passage of Plasmodium through the midgut and the salivary glands, this study identifies a striking overlap in the molecular responses of these two epithelia to parasite invasion.
Asunto(s)
Anopheles/parasitología , Proteínas de Insectos/fisiología , Plasmodium berghei/crecimiento & desarrollo , Glándulas Salivales/parasitología , Esporozoítos/crecimiento & desarrollo , Animales , Anopheles/genética , Anopheles/metabolismo , Western Blotting , Femenino , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Proteínas de Insectos/metabolismo , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Glándulas Salivales/metabolismoRESUMEN
BACKGROUND: Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission. METHODOLOGY: We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas. PRINCIPAL FINDINGS: We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors. CONCLUSIONS: Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism.
Asunto(s)
Anopheles/genética , Mosaicismo , Animales , Anopheles/clasificación , Evolución Biológica , Cromosomas Artificiales Bacterianos , Femenino , Marcadores Genéticos , Variación Genética , Genoma , Repeticiones de Microsatélite/genéticaRESUMEN
Drosophila melanogaster Suppressor of Under-Replication (SuUR) gene encodes a protein that modulates replicative properties of heterochromatin in endocycles of polytene cells. The SuUR mutation abolishes underreplication of intercalary heterochromatin and results in partial underreplication of pericentric heterochromatin. We performed a genome-wide mapping of SUUR target genes in non-polytenic Drosophila Kc cells by using the DamID approach. We show that SUUR preferentially binds genes that are transcriptionally silent and late-replicated. Distinct subsets of SUUR targets are associated with PcG proteins (Pc and Esc; Polycomb and Extra sexcombs), heterochromatic proteins [HP1 and SU(VAR)3-9] and B-type lamin. The SUUR binding profile negatively correlates with the DNA polytenization levels of salivary gland polytene chromosomes. Finally, SUUR target genes are repressed in Drosophila embryos and gradually activated later in development. Together these results suggest that SUUR is a ubiquitous marker of heterochromatin in different cell types.
Asunto(s)
Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Animales , Células Cultivadas , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Regulación del Desarrollo de la Expresión Génica , Heterocromatina/metabolismo , N-Metiltransferasa de Histona-Lisina , Lamina Tipo B/genética , Lamina Tipo B/metabolismo , Complejo Represivo Polycomb 1 , Complejo Represivo Polycomb 2 , Unión ProteicaRESUMEN
Mosquitoes are vectors of parasitic and viral diseases of immense importance for public health. The acquisition of the genome sequence of the yellow fever and Dengue vector, Aedes aegypti (Aa), has enabled a comparative phylogenomic analysis of the insect immune repertoire: in Aa, the malaria vector Anopheles gambiae (Ag), and the fruit fly Drosophila melanogaster (Dm). Analysis of immune signaling pathways and response modules reveals both conservative and rapidly evolving features associated with different functional gene categories and particular aspects of immune reactions. These dynamics reflect in part continuous readjustment between accommodation and rejection of pathogens and suggest how innate immunity may have evolved.
Asunto(s)
Aedes/genética , Anopheles/genética , Evolución Molecular , Inmunidad Innata/genética , Insectos Vectores/genética , Aedes/inmunología , Animales , Anopheles/inmunología , Péptidos Catiónicos Antimicrobianos/fisiología , Proteínas Portadoras/genética , Proteínas Portadoras/fisiología , Drosophila melanogaster/genética , Drosophila melanogaster/inmunología , Genes de Insecto , Proteínas de Insectos/genética , Proteínas de Insectos/fisiología , Insectos Vectores/inmunología , Malaria/transmisión , Melaninas/metabolismo , Familia de Multigenes , Transducción de Señal , Especificidad de la EspecieRESUMEN
The melanization reaction of insects requires activation of pro-phenoloxidase by a proteolytic cascade leading to melanin production. Studies in adult mosquitoes have shown that bacteria are efficiently melanized in the hemocoel, but the contribution of melanization to survival after bacterial infections has not been established. Here we show that the Anopheles gambiae noncatalytic serine protease CLIPA8, an essential factor for Plasmodium ookinete melanization, is also required for melanization of bacteria in adult mosquitoes. CLIPA8 silencing by RNA interference inhibits pro-phenoloxidase activation and melanization of bacteria in the hemolymph following microbial challenge. However, CLIPA8 is not required for wound melanization nor for melanotic pseudotumor formation in serpin2 knockdown mosquitoes, suggesting a specific role for pathogen melanization. Surprisingly, CLIPA8 knockdown mosquitoes are as resistant to bacterial challenge as controls, indicating that melanization is not essential for defense against bacteria and questions its precise role in mosquito immunity.
Asunto(s)
Anopheles/microbiología , Anopheles/fisiología , Melaninas/fisiología , Animales , Anopheles/genética , Infecciones Bacterianas/fisiopatología , Infecciones por Escherichia coli/fisiopatología , Silenciador del Gen , Hemolinfa/fisiología , Reacción en Cadena de la Polimerasa , ARN/genética , ARN/aislamiento & purificación , ARN Interferente Pequeño/genética , Serina Endopeptidasas/deficiencia , Serina Endopeptidasas/genética , Serina Endopeptidasas/metabolismo , Infecciones Estafilocócicas/fisiopatologíaRESUMEN
The African mosquito Anopheles gambiae is the major vector of human malaria. We report a genome-wide survey of mosquito gene expression profiles clustered temporally into developmental programs and spatially into adult tissue-specific patterns. Global expression analysis shows that genes that belong to related functional categories or that encode the same or functionally linked protein domains are associated with characteristic developmental programs or tissue patterns. Comparative analysis of our data together with data published from Drosophila melanogaster reveal an overall strong and positive correlation of developmental expression between orthologous genes. The degree of correlation varies, depending on association of orthologs with certain developmental programs or functional groups. Interestingly, the similarity of gene expression is not correlated with the coding sequence similarity of orthologs, indicating that expression profiles and coding sequences evolve independently. In addition to providing a comprehensive view of temporal and spatial gene expression during the A. gambiae life cycle, this large-scale comparative transcriptomic analysis has detected important evolutionary features of insect transcriptomes.