AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002
Jason AL Jeffery
AbstractCoquillettidia linealis is a severe pest on some of the Moreton Bay islands in Queensland, Australia, but little is known of its breeding habitats and biology. Because of its high abundance and its association with Ross River (RR) and Barmah Forest (BF) viruses by field isolation, its vector competence was evaluated in the laboratory by feeding dilutions of both viruses in blood. For RR, Cq. linealis was of comparable efficiency to Ochlerotatus vigilax (Skuse), recognised as being a major vector. Results were as follows for Cq. linealis and Oc. vigilax, respectively: dose to infect 50%, 102.2 and <101.7 CCID50/mosquito; 88% and 90% disseminated infection at 4 days postinfection; transmission at 4 days with rates of 68,92% and 25,60%. For BF dose to infect 50%, 102.7 and 102.0; disseminated infection rates on first transmission day (day 6), 40% and 70%; transmission rates of 8,16% and 0,10%. As a capillary-tube method was used rather than suckling mice to demonstrate transmission, transmission rates may be underestimates. This, the first study of the vector competence of Cq. linealis in Australia, demonstrates that this species deserves control on the southern Moreton Bay islands. [source]

THE CONTRIBUTION OF AN HOURGLASS TIMER TO THE EVOLUTION OF PHOTOPERIODIC RESPONSE IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII

EVOLUTION, Issue 10 2003
W. E. Bradshaw
Abstract Photoperiodism, the ability to assess the length of day or night, enables a diverse array of plants, birds, mammals, and arthropods to organize their development and reproduction in concert with the changing seasons in temperate climatic zones. For more than 60 years, the mechanism controlling photoperiodic response has been debated. Photoperiodism may be a simple interval timer, that is, an hourglasslike mechanism that literally measures the length of day or night or, alternatively, may be an overt expression of an underlying circadian oscillator. Herein, we test experimentally whether the rhythmic response in Wyeomyia smithii indicates a causal, necessary relationship between circadian rhythmicity and the evolutionary modification of photoperiodic response over the climatic gradient of North America, or may be explained by a simple interval timer. We show that a day-interval timer is sufficient to predict the photoperiodic response of W. smithii over this broad geographic range and conclude that rhythmic responses observed in classical circadian-based experiments alone cannot be used to infer a causal role for circadian rhythmicity in the evolution of photoperiodic time measurement. More importantly, we argue that the pursuit of circadian rhyth-micity as the central mechanism that measures the duration of night or day has distracted researchers from consideration of the interval-timing processes that may actually be the target of natural selection linking internal photoperiodic time measurement to the external seasonal environment. [source]

Seasonal Prevalence of Mosquitoes Collected from Light Traps in Korea (1999-2000)

ENTOMOLOGICAL RESEARCH, Issue 1 2003
Heung Chul KIM
ABSTRACT Adult mosquito collections were conducted from 1999 through 2000 at 29 US military installations located in six provinces in the Republic of Korea (ROK). Adult mosquitoes were collected in New Jersey light traps from 15 May to 15 October each year. Adult mosquito surveillance was conducted to determine the appropriate time for pesticide applications at each of the Army installations. A total of 68,051 and 62,526 adults were collected in 1999 and 2000 respectively, comprising 53,983 (79.3%) females and 14,068 (20.7%) males in 1999, and 50,274 (80.4%) females and 12,252 (19.6%) males in 2000. A total of 19 species from 7 genera were collected. The most common species collected were Anopheles sinensis (34.2%), Culex tritaeniorhynchus (29.4%), Aedes vexans nipponii (18.2%) and Culex pipiens (16.8%). Anopheles sinensis were collected at the same level while Culex tritaeniorhynchus decreased by 6.2% in 2000. The weekly population densities for some species were variable for each of the years, apparently as a result of changing weather conditions. [source]

Ribosomal DNA spacer genotypes of the Anopheles bancroftii group (Diptera: Culicidae) from Australia and Papua New Guinea

INSECT MOLECULAR BIOLOGY, Issue 5 2001
N. W. Beebe
Abstract Mosquitoes of the Anopheles bancroftii group collected from Northern Australia and Papua New Guinea (PNG) were investigated for sequence variation within the ribosomal DNA ITS2. Wing fringe morphology originally used to identify members of this group was compared to genotypes identified by restriction fragment length polymorphism analysis (RFLP) and heteroduplex analysis (HDA) of the rDNA ITS2. Members of this group separated into four RFLP genotypes (A, B, C and D) with some genotypes displaying wing fringe polymorphisms. Heteroduplex analysis of the ITS2 within and between populations identified genotype A as containing two geographically separate ITS2 sequences: A1 from the Northern Territory of Australia and A2 from Queensland and the Western Province of PNG. Genotypes B and C and genotypes C and D were found sympatric and appeared to be evolving independently suggesting the possibility of cryptic species. Genotype C contained two ITS2 sequence types within the genome. [source]

Spatial variation in population growth rate and community structure affects local and regional dynamics

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2008
M. Kurtis Trzcinski
Summary 1Theory predicting that populations with high maximum rates of increase (rmax) will be less stable, and that metapopulations with high average rmax will be less synchronous, was tested using a small protist, Bodo, that inhabits pitcher plant leaves (Sarracenia purpurea L.). The effects of predators and resources on these relationships were also determined. 2Abundance data collected for a total of 60 populations of Bodo, over a period of 3 months, at six sites in three bogs in eastern Canada, were used to test these predictions. Mosquitoes were manipulated in half the leaves partway through the season to increase the range of predation rates. 3Dynamics differed greatly among leaves and sites, but most populations exhibited one or more episodes of rapid increase followed by a population crash. Estimates of rmax obtained using a linear mixed-effects model, ranged from 1·5 to 2·7 per day. Resource levels (captured insect) and midge abundances affected rmax. 4Higher rmax was associated with greater temporal variability and lower synchrony as predicted. However, in contrast to expectations, populations with higher rmax also had lower mean abundance and were more suppressed by predators. 5This study demonstrates that the link between rmax and temporal variability is key to understanding the dynamics of populations that spend little time near equilibrium, and to predicting and interpreting the effects of community structure on the dynamics of such populations. [source]

Orientation of Culex mosquitoes to carbon dioxide-baited traps: flight manoeuvres and trapping efficiency

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2006
M. F. Cooperband
Abstract., Females of Culex quinquefasciatus Say and Culex tarsalis Coquillet (Diptera: Culicidae) in the host-seeking stage were released and video recorded in three dimensions in a large field wind tunnel as they flew to four kinds of CO2 -baited mosquito traps. The trapping efficiency (number of mosquitoes approaching compared to the number caught) was determined for each trap type. The Encephalitis Virus Surveillance (EVS), Mosquito Magnet Freedom (MMF) and Mosquito Magnet Liberty (MML) traps captured only 13,16% of approaching Cx. quinquefasciatus females, whereas the Mosquito Magnet-X (MMX) trap captured 58%. Similar results were obtained for Cx. tarsalis. Orientation behaviour and flight parameters of mosquitoes approaching the four traps were compared. Mosquitoes spent the most time orienting to the EVS trap. Flight speed decreased as mosquitoes entered the vicinity of each trap and a large portion of their time was spent within 30 cm downwind of the traps. Flights became highly tortuous downwind of the poorly performing traps and just upwind of the MMX trap. Differences between traps and possible explanations for the superior performance of the MMX trap are considered. [source]

SAAG-4 is a novel mosquito salivary protein that programmes host CD4+ T cells to express IL-4

PARASITE IMMUNOLOGY, Issue 6 2009
V.D. BOPPANA
Summary Mosquitoes represent the most important vector for transmitting pathogens that cause human disease. Central to pathogen transmission is the ability to divert the host immune system away from Th1 and towards Th2 responsiveness. Identification of the mosquito factor(s) critical for programming Th2 responsiveness should therefore lead to strategies to neutralize their function and thus prevent disease transmission. In the current study, we used a TCR transgenic adoptive transfer system to screen gene products present in the saliva of the mosquito Aedes aegypti for their ability to programme CD4 T cells to express the signature Th2 cytokine IL-4. The clone SAAG-4 encodes a secreted protein with a predicted size of 20 kDa whose function has previously been uncharacterized. Notably, SAAG-4 reduced host CD4 T cell expression of the signature Th1 cytokine IFN-, while simultaneously increasing expression of IL-4. SAAG-4 is therefore the first identified mosquito factor that can programme Th2 effector CD4 T cell differentiation. [source]

Biotec Visions 2009, November,December

BIOTECHNOLOGY JOURNAL, Issue 11 2009
Article first published online: 13 NOV 200
Nobel Prizes 2009: Ribosomes , Telomeres and telomerases Encyclopaedia of Life Sciences: SNP genotyping technologies , Molecular mimicry Special issues: Chinese microbial ecology , Advances in yeast proteomics , MALDI-TOF "Flip-flop" drug susceptibility test News: Phytophthora infestans genome , Sequencing bacterial transcriptomes , Stem cells from fat , Selecting green clones , Endogenous mutagenic force , Green batteries , Tobacco-produced vaccine , O2 transport in artificial liver , Endolysins instead of antibiotics , Quick switch key for mitochondria , Climate change shrinks algae , Bacteria degrade microcystins Opinion: Will biotech banish wrinkles forever? Most Read Synthetic biology Tips and tricks: Trypsinizing cells Biotech round the world: Kenya Writing Tips: IMRAD or RAMID? Briefs: Metabolic Engineering award , Mosquitoes , from foe to friend , Mobile phone microscope Test your Knowledge: Do you recognize this? In Brief: The horse pathogen Rhodococcus equi [source]

Structure,Activity Relationship Studies on Derivatives of Eudesmanolides from Inula helenium as Toxicants against Aedes aegypti Larvae and Adults

CHEMISTRY & BIODIVERSITY, Issue 7 2010
Charles
Abstract An Aedes aegypti larval toxicity bioassay was performed on compounds representing many classes of natural compounds including polyacetylenes, phytosterols, flavonoids, sesquiterpenoids, and triterpenoids. Among these compounds, two eudesmanolides, alantolactone, and isoalantolactone showed larvicidal activities against Ae. aegypti and, therefore, were chosen for further structure,activity relationship study. In this study, structural modifications were performed on both alantolactone and isoalantolactone in an effort to understand the functional groups necessary for maintaining and/or increasing its activity, and to possibly lead to more effective insect-control agents. All parent compounds and synthetic modification reaction products were evaluated for their toxic activities against Ae. aegypti larvae and adults. Structure modifications included epoxidations, reductions, catalytic hydrogenations, and Michael additions to the ,,, -unsaturated lactones. None of the synthetic isomers synthesized and screened against Ae. aegypti larvae were more active than isoalantolactone itself which had an LC50 value of 10.0,,g/ml. This was not the case for analogs of alantolactone for which many of the analogs had larvicidal activities ranging from 12.4 to 69.9,,g/ml. In general, activity trends observed from Ae. aegypti larval screening were not consistent with observations from adulticidal screening. The propylamine Michael addition analog of alantolactone was the most active adulticide synthesized with an LC50 value of 1.07,,g/mosquito. In addition, the crystal structures of both alantolactone and isoalantolactone were determined using CuK, radiation, which allowed their absolute configurations to be determined based on resonant scattering of the light atoms. [source]

Oviposition decreased in response to enriched water: a field study of the pitcher-plant mosquito, Wyeomyia smithii

ECOLOGICAL ENTOMOLOGY, Issue 1 2007
DAVID HOEKMAN
Abstract 1.,Environmental cues are known to influence oviposition behaviour in mosquitoes, with important consequences for larval survival and insect population dynamics. Enriched microhabitats have been shown to be preferred oviposition sites. 2.,In a field experiment designed to determine whether ovipositing mosquitoes are sensitive to different levels of nutrient enrichment, new pitcher-plant (Sarracenia purpurea) leaves were opened and enriched with 0, 2, or 20 dead ants, and the number of pitcher-plant mosquito (Wyeomyia smithii) larvae resulting from subsequent oviposition were measured. 3.,Oviposition rates were higher in leaves with low levels of enrichment (0 and 2 ants per leaf), although larval development was enhanced at the highest enrichment level. 4.,Results suggest that, although these mosquito larvae are nutrient limited, ovipositing females preferentially avoid highly enriched leaves. This counterintuitive result may be due to low oxygen concentrations or a masked cue in enriched leaves, and contrasts with other oviposition studies. [source]

Oviposition habitat selection for a predator refuge and food source in a mosquito

ECOLOGICAL ENTOMOLOGY, Issue 3 2005
J. Guillermo Bond
Abstract., 1.,The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2.,A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3.,Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0,99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4.,The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5.,Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae. [source]

Factors influencing the seasonal life history of the pitcher-plant mosquito, Wyeomyia smithii

ECOLOGICAL ENTOMOLOGY, Issue 2 2005
Alan O. Bergland
Abstract., 1.,The effects of resource levels, thermal microclimate, and seasonal oviposition patterns on fecundity and survivorship in the pitcher-plant mosquito, Wyeomyia smithii (Coq.), were examined at a northern Wisconsin bog over the course of 2 years. Wyeomyia smithii are bivoltine at this locality, thereby enabling the study of summer and overwintering generations separately. 2.,Nutrient resources of W. smithii were not limiting and there was no indication of density-dependent survivorship or fecundity. 3.,Oviposition rates were highest in young, large pitchers and individual mosquitoes appeared to allocate only a few eggs to any one leaf. 4.,Winter was the harsh season, and the principal manifestation of seasonal harshness was reduced survivorship. 5.,Overwintering W. smithii that had been oviposited later in the summer had a higher odds of survival than those oviposited earlier in the summer. 6.,It was concluded that dispersal of eggs among many pitchers serves to spread the risk of encountering lethal winter temperatures among spatially unpredictable patches. [source]

Ecology of invasive mosquitoes: effects on resident species and on human health

ECOLOGY LETTERS, Issue 5 2005
Steven A. Juliano
Abstract Investigations of biological invasions focus on patterns and processes that are related to introduction, establishment, spread and impacts of introduced species. This review focuses on the ecological interactions operating during invasions by the most prominent group of insect vectors of disease, mosquitoes. First, we review characteristics of non-native mosquito species that have established viable populations, and those invasive species that have spread widely and had major impacts, testing whether biotic characteristics are associated with the transition from established non-native to invasive. Second, we review the roles of interspecific competition, apparent competition, predation, intraguild predation and climatic limitation as causes of impacts on residents or as barriers to invasion. We concentrate on the best-studied invasive mosquito, Aedes albopictus, evaluating the application of basic ecological theory to invasions by Aedes albopictus. We develop a model based on observations of Aedes albopictus for effects of resource competition and predation as barriers to invasion, evaluating which community and ecosystem characteristics favour invasion. Third, we evaluate the ways in which invasive mosquitoes have contributed to outbreaks of human and animal disease, considering specifically whether invasive mosquitoes create novel health threats, or modify disease transmission for existing pathogen,host systems. [source]

Effects of crowding on populations of Aedes albifasciatus larvae under laboratory conditions

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2000
Raquel M. Gleiser
Abstract Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) is a neotropical flood water mosquito, incriminated as the main vector of the western equine encephalitis virus, and which affects beef and milk production in central Argentina. The short time required to hatch and develop from egg to adult, usually in temporary pools, suggests a strategy which allows for exploitation of transient pools, thus evading predation and interspecific competition. Under these conditions intra specific competition could represent a major density-dependent source of larval mortality, but the relative importance of density-dependent regulation of mosquito populations has generated controversy. Therefore we examined the effects of larval density on basic population characteristics of Ae. albifasciatus in the laboratory. Larvae were obtained by synchronous hatching of eggs laid by field-trapped females. Emerging larvae (L1) were used to build cohorts of different initial densities, kept in plastic trays with 400 ml of distilled water, and food supplied daily during the first 10 days (0.1 g per larvae day,1). Age-specific development time and specific and relative mortality were estimated, and their relation to initial larval density was assessed through linear and non-linear regressions and correlation analysis. First hatching was registered 3 h after flooding the eggs. Higher levels of pre-adult mortality were detected in groups with higher densities. Specific mortality and average time to enter a stage of L1 to L3 could directly be related to initial larval density, but no significant relations were found for L4 and pupae. Results suggest that crowding could be a factor capable of regulating the density of natural populations of Ae. albifasciatus. [source]

Characterization of the Hox gene cluster in the malaria vector mosquito, Anopheles gambiae

EVOLUTION AND DEVELOPMENT, Issue 6 2000
Martin P. Devenport
SUMMARY The Hox genes play a central role in regulating development and are involved in the specification of cell fates along the anteroposterior axis. In insects and vertebrates, these genes are clustered and organized in an arrangement that is largely conserved across evolutionary lineages. By exploiting the sequence conservation of the homeobox, orthologues of the Hox genes Sex combs reduced (Scr ,), fushi tarazu (ftz,), Antennapedia (Antp), Ultrabithorax (Ubx,), and abdominal-A (abd-A) have been isolated from the malaria vector mosquito, Anopheles gambiae. These genes were first identified in Drosophila, where they achieve a high level of functional complexity, in part, by the use of alternative promoters, polyadenylation sites, and splicing to generate different protein isoforms. Preliminary analyses of the Anopheles Hox genes suggest that they do not achieve their functional complexity in the same manner. Using a combination of in situ hybridization to polytene chromosomes and chromosome walking, the Anopheles Hox genes have been localized to a single cluster in the region 19D,E on chromosome 2R, a situation distinct from that of Drosophila where the Hox complex is split into two clusters. This study, therefore, provides a framework for future comparative analyses of the structure, organization, and expression of developmental regulatory genes between the lower and higher Diptera. Moreover, the genes that have been isolated enhance the genetic and physical maps of chromosome 2R in this medically important mosquito species. [source]

Malaria sporozoite antigen-directed genome-wide response in transgenic Drosophila,

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 3 2009
Jizhou Yan
Abstract Malaria kills a million people annually. Understanding the relationship between a causative parasite, Plasmodium falciparum, and the mosquito vector might suggest novel prevention approaches. We created and transformed into Drosophila two genes encoding, thrombospondin-related adhesive protein (TRAP) and circumsporozoite protein (CSP), found on the cell surface of Plasmodium sporozoites. To understand a model insect's response, we induced these proteins separately and together, performing whole genome microarray analysis measuring gene expression changes. Gene ontology classification of responding genes reveals that TRAP and CSP strongly and differentially influence Drosophila genes involved with cell motility and gene regulation, respectively; however, the most striking effects are on the immune system. While immune-related genes are but modestly elevated compared with responses to sepsis, there is a marked repression of the Toll pathway. This suggests: (1) how Plasmodium infection of the mosquito might use TRAP and CSP to modulate the host insect's physiology to promote sporozoite survival and transmission to man and (2) that approaches to elevate expression of the mosquito's Toll pathway might lead to novel methods of malaria prevention. genesis 47:196,203, 2009. © 2009 Wiley-Liss, Inc. [source]

Flying vaccinator; a transgenic mosquito delivers a Leishmania vaccine via blood feeding

INSECT MOLECULAR BIOLOGY, Issue 3 2010
D. S. Yamamoto
Abstract ,Flying vaccinator' is the concept of using genetically engineered hematophagous insects to deliver vaccines. Here we show the generation of a transgenic anopheline mosquito that expresses the Leishmania vaccine candidate, SP15, fused to monomeric red fluorescent protein (mDsRed) in its salivary glands. Importantly, mice bitten repeatedly by the transgenic mosquitoes raised anti-SP15 antibodies, indicating delivery of SP15 via blood feeding with its immunogenicity intact. Thus, this technology makes possible the generation of transgenic mosquitoes that match the original concept of a ,flying vaccinator'. However, medical safety issues and concerns about informed consent mitigate the use of the ,flying vaccinator' as a method to deliver vaccines. We propose that this expression system could be applied to elucidate saliva,malaria sporozoite interactions. [source]

Gene structure and expression of nanos (nos) and oskar (osk) orthologues of the vector mosquito, Culex quinquefasciatus

INSECT MOLECULAR BIOLOGY, Issue 5 2008
J. Juhn
Abstract The products of the maternal-effect genes, nanos (nos) and oskar (osk), are important for the development of germ cells in insects. Furthermore, these genes have been proposed as candidates for donating functional DNA regulatory sequences for use in gene drive systems to control transmission of mosquito-borne pathogens. The nos and osk genes of the cosmopolitan vector mosquito, Culex quinquefasciatus, encode proteins with domains common to orthologues found in other mosquitoes. Expression analyses support the conclusion that the role of these genes is conserved generally among members of the nematocera. Hybridization in situ analyses reveal differences in mRNA distribution in early embryos in comparison with the cyclorraphan, Drosophila melanogaster, highlighting a possible feature in the divergence of the clades each insect represents. [source]

Molecular characterization of the Aedes aegypti odorant receptor gene family

INSECT MOLECULAR BIOLOGY, Issue 5 2007
J. Bohbot
Abstract The olfactory-driven blood-feeding behaviour of female Aedes aegypti mosquitoes is the primary transmission mechanism by which the arboviruses causing dengue and yellow fevers affect over 40 million individuals worldwide. Bioinformatics analysis has been used to identify 131 putative odourant receptors from the A. aegypti genome that are likely to function in chemosensory perception in this mosquito. Comparison with the Anopheles gambiae olfactory subgenome demonstrates significant divergence of the odourant receptors that reflects a high degree of evolutionary activity potentially resulting from their critical roles during the mosquito life cycle. Expression analyses in the larval and adult olfactory chemosensory organs reveal that the ratio of odourant receptors to antennal glomeruli is not necessarily one to one in mosquitoes. [source]

Robust salivary gland-specific transgene expression in Anopheles stephensi mosquito

INSECT MOLECULAR BIOLOGY, Issue 4 2006
S. Yoshida
Abstract Malaria sporozoites invade the mosquito salivary glands and wait in the salivary duct until the next blood feeding. The mechanisms of the process and molecules involved in the salivary gland invasion remain largely unknown. To establish a robust salivary gland-specific transgene expression in Anopheles stephensi, we obtained a salivary gland-specific promoter for a gene encoding anopheline antiplatelet protein (AAPP). The aapp promoter is a female salivary gland-specific and blood meal-inducible strong promoter. Using this promoter, we generated a transgenic An. stephensi expressing abundant Discosoma sp. red fluorescent protein (DsRed) in the distal-lateral lobes of the glands, where the sporozoites invade preferentially. These results open up the possibilities of elucidating salivary gland,parasite interactions and generating transgenic mosquitoes refractory to parasites. [source]

High efficiency site-specific genetic engineering of the mosquito genome

INSECT MOLECULAR BIOLOGY, Issue 2 2006
D. D. Nimmo
Abstract Current techniques for the genetic engineering of insect genomes utilize transposable genetic elements, which are inefficient, have limited carrying capacity and give rise to position effects and insertional mutagenesis. As an alternative, we investigated two site-specific integration mechanisms in the yellow fever mosquito, Aedes aegypti. One was a modified CRE/lox system from phage P1 and the other a viral integrase system from Streptomyces phage phi C31. The modified CRE/lox system consistently failed to produce stable germline transformants but the phi C31 system was highly successful, increasing integration efficiency by up to 7.9-fold. The ability to efficiently target transgenes to specific chromosomal locations and the potential to integrate very large transgenes has broad applicability to research on many medically and economically important species. [source]

An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi

INSECT MOLECULAR BIOLOGY, Issue 2 2005
F. Lombardo
Abstract Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium,Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands. [source]

Identification of a distinct family of genes encoding atypical odorant-binding proteins in the malaria vector mosquito, Anopheles gambiae

INSECT MOLECULAR BIOLOGY, Issue 6 2003
P. X. Xu
Abstract We performed a genome-wide analysis for candidate odorant-binding protein (OBP) genes in the malaria vector Anopheles gambiae (Ag). We identified fifty-seven putative genes including sixteen genes predicted to encode distinct, higher molecular weight proteins that lack orthologues in Drosophila. Expression analysis indicates that several of these atypical AgOBPs are transcribed in chemosensory organs in adult and immature stages. Phylogenetic analysis of the Anopheles and Drosophila OBP families reveals these proteins fall into several clusters based on sequence similarity and suggests the atypical AgOBP genes arose in the mosquito lineage after the divergence of mosquitoes and flies. The identification of these AgOBP genes is the first step towards determining their biological roles in this economically and medically important insect. [source]

Development of an orally infectious Sindbis virus transducing system that efficiently disseminates and expresses green fluorescent protein in Aedes aegypti

INSECT MOLECULAR BIOLOGY, Issue 2 2003
D. J. Pierro
Abstract We have constructed an orally infectious Sindbis virus, ME2/5,2J/GFP, that expresses green fluorescent protein (GFP) in the midgut of Aedes aegypti and in other tissues as the virus disseminates. This virus has two unique features that are improvements over the SIN-based expression systems currently used in mosquitoes. First, a subgenomic RNA promoter and GFP coding sequence is located 5,- to the second subgenomic promoter and structural genes of the virus. Second, the E2 glycoprotein gene of TE/5,2J/GFP is replaced with the E2 gene of MRE16 SIN virus. The first feature enhances virus genome stability during virus dissemination from the midgut to other tissues and the second allows efficient virus entry into the midgut epithelial cells and then spread of the virus throughout the mosquito. [source]

Linkage map organization of expressed sequence tags and sequence tagged sites in the mosquito, Aedes aegypti

INSECT MOLECULAR BIOLOGY, Issue 4 2002
D. W. Severson
Abstract A composite genetic linkage map for the yellow fever mosquito Aedes aegypti was constructed based on restriction fragment length polymorphism (RFLP), single nucleotide polymorphism (SNP) and single strand conformation polymorphism (SSCP) markers. The map consists of 146 marker loci distributed across 205 cM, and includes several morphological mutant marker loci. Most of the genetic markers are derived from random cDNAs or Ae. aegypti genes of known function. A number of markers are derived from random genomic DNAs, including several cloned RAPD-PCR fragments, and also several cDNAs from Drosophila melanogaster. Most of the random cDNAs (80.2%) have high BlastX sequence identities to known genes, with the majority of matches to genes from D. melanogaster. Access to sequence data for all markers will facilitate their continued development for use in high-throughput SNP marker analyses and also provides additional physical anchor points for an anticipated genome sequencing effort. [source]

Isolation of cDNA clones encoding putative odourant binding proteins from the antennae of the malaria-transmitting mosquito, Anopheles gambiae

INSECT MOLECULAR BIOLOGY, Issue 2 2002
Harald Biessmann
Abstract One way of controlling disease transmission by blood-feeding mosquitoes is to reduce the frequency of insect,host interaction, thus reducing the probability of parasite transmission and re-infection. A better understanding of the olfactory processes responsible for allowing mosquitoes to identify human hosts is required in order to develop methods that will interfere with host seeking. We have therefore initiated a molecular approach to isolate and characterize the genes and their products that are involved in the olfactory recognition pathway of the mosquito Anopheles gambiae, which is the main malaria vector in sub-Saharan Africa. We report here the isolation and preliminary characterization of several cDNAs from male and female A. gambiae antennal libraries that encode putative odourant binding proteins. Their conceptual translation products show extensive sequence similarity to known insect odourant binding proteins (OBPs)/pheromone binding proteins (PBPs), especially to those of D. melanogaster. The A. gambiae OBPs described here are expressed in the antennae of both genders, and some of the A. gambiae OBP genes are well conserved in other disease-transmitting mosquito species, such as Aedes aegypti and Culex quinquefasciatus. [source]

Germ line transformation of the yellow fever mosquito, Aedes aegypti, mediated by transpositional insertion of a piggyBac vector

INSECT MOLECULAR BIOLOGY, Issue 2 2002
N. F. Lobo
Mosquito-vectored diseases such as yellow fever and dengue fever continue to have a substantial impact on human populations world-wide. Novel strategies for control of these mosquito vectored diseases can arise through the development of reliable systems for genetic manipulation of the insect vector. A piggyBac vector marked with the Drosophila melanogaster cinnabar (cn) gene was used to transform the white-eyed khw strain of Aedes aegypti. Microinjection of preblastoderm embryos resulted in four families of cinnabar transformed insects. An overall transformation frequency of 4%, with a range of 0% to as high as 13% for individual experiments, was achieved when using a heat-shock induced transposase providing helper plasmid. Southern hybridizations indicated multiple insertion events in three of four transgenic lines, while the presence of duplicated target TTAA sites at either ends of individual insertions confirmed characteristic piggyBac transposition events in these three transgenic lines. The transgenic phenotype has remained stable for more than twenty generations. The transformations effected using the piggyBac element establish the potential of this element as a germ-line transformation vector for Aedine mosquitoes. [source]

Developmental variation in epidermal growth factor receptor size and localization in the malaria mosquito, Anopheles gambiae

INSECT MOLECULAR BIOLOGY, Issue 6 2001
G. Lycett
Abstract The AGER gene encoding the epidermal growth factor receptor (EGFR) of the malaria mosquito Anopheles gambiae was cloned and sequenced. It represents a canonical member of this family of tyrosine kinase proteins exhibiting many similarities to orthologues from other species, both on the level of genomic organization and protein structure. The mRNA can be detected throughout development. Western analysis with an antibody raised against the extracellular domain of the mosquito protein suggests developmental variation in protein size and location that may be involved in the function of EGFR in the mosquito. [source]

Molecular cloning of two prophenoloxidase genes from the mosquito Aedes aegypti

INSECT MOLECULAR BIOLOGY, Issue 1 2001
A. S. Taft
Abstract The biosynthesis of melanotic materials is an important process in the life of a mosquito. Melanin production is critical for many diverse processes such as egg chorion tanning, cuticular sclerotization, and melanotic encapsulation of metazoan parasites. Prophenoloxidase plays a critical role in this biochemical cascade. Two cDNAs, one full length and one partial clone, and two genomic clones encoding prophenoloxidase (pro-PO) were isolated from the yellow fever mosquito, Aedes aegypti. The full-length cDNA, pAaProPO1, is 2286 bp long with a 2055 bp open reading frame encoding a 685 amino acid protein that shares 89% identity with Armigeres subalbatus pro - PO. It contains two putative copper binding domains (amino acids 197,243 and 346,423) that are homologous to other insect pro-POs. AaProPO1 messenger RNA (mRNA) was detected by reverse transcription polymerase chain reaction (RT-PCR) only from third-stage larvae and not in adult mosquitoes after blood feeding, during the melanotic encapsulation of Dirofilaria immitis microfilariae or following exposure to bacteria. A 750 bp fragment of the second cDNA (pAaProPO2) was cloned using RT-PCR from mRNA obtained from 14-day postovipostional eggs. AaProPO2 mRNA was not found in any other life stages, and may be in low abundance or transiently expressed. AaProPO2 and AaProPO1 each contain three introns that are 60, 68 and 58 bp and 61, 69 and 59 bp long, respectively, and the intron sequences of these two genes are not similar. [source]

Structure of Hermes integrations in the germline of the yellow fever mosquito, Aedes aegypti

INSECT MOLECULAR BIOLOGY, Issue 1 2000
N. Jasinskiene
Abstract The Hermes transposable element is derived from the house fly, Musca domestica, and can incorporate into the germline of the yellow fever mosquito, Aedes aegypti. Preliminary Southern analyses indicated that Hermes integrated along with the marker gene into the mosquito genomic DNA. Here we show that Hermes integrations are accompanied by the integration of the donor plasmid as well. In addition, breaks in the donor plasmid DNAs do not occur precisely, or at the end of the terminal inverted repeats, and are accompanied by small deletions in the plasmids. Furthermore, integrations do not cause the typical 8-bp duplications of the target site DNA. No integrations are observed in the absence of a source of Hermes transposase. The Hermes transposase clearly did not catalyse precise cut-and-paste transposition in these transformed lines. It may have integrated the transposon through general recombination or through a partial replicative transposition mechanism. The imprecision of Hermes integration may result from interactions of the transposase with an endogenous hAT -like element in the mosquito genome. [source]