Chemical Composition and Use of Momordica charantia L. and Hyptis spicigera Lam. Extracts as Mosquito Larvicides and Insect Growth Regulators against Malarial Vector, Anopheles gambiae Giles

Background: Mosquitoes are responsible of numerous vector-borne diseases and among these diseases is malaria which takes away lives of thousands of people, especially children of under five, particularly in Africa. To reduce the mortality and economic burdens of this deadly disease, synthetic insecticide has been of use to control its main vector, Anopheles gambiae. Due to adverse effects caused by these conventional products on non-target organisms and the environment, plants have been of first choice as they proved their effectiveness against mosquitoes and are said to be eco-friendly and relatively safer. Therefore, the aim of this study was to screen the phytochemicals and determine the larvicidal and adult emergence exhibitory activities of Momordica charantia and Hyptis spicigera leaves extracts against Anopheles gambiae larvae. Methods: The WHO standard protocol for larvicidal activity and IGRs was followed up and concentrations from 500 - 2000 ppm for larvicidal and 500 - 1500 ppm for IGRs were set up. Results: There was the presence of alkaloids, flavonoids, tannins, phenols, steroids, terpenoids and oils in Momordica charantia against alkaloids, taponins, tannins, phenols, steroids, terpenoids and oils in Hyptis spicigera. Methanol crude extract registered the lowest LC50 value of 270.6 ppm followed by ethyl acetate and hexane fractions recorded the LC50 of 742.1 and 756 ppm, respectively for larvicidal activity of Momordica charantia against LC50 of 760 and 867.5 ppm for hexane fraction and methanol crude extract, respectively for Hyptis spicigera. Methanol crude extract and hexane fraction of both plants as well as the ethyl acetate fraction of M. charantia registered greater emergence inhibition with IE50 values of 590.2, 842.3 and 982 ppm for methanol crude extract, hexane and ethyl acetate fractions of M. charantia, respectively against 901.7 and 873.2 for methanol crude extract and hexane fraction of H. spicigera, respectively. Conclusion: The toxicity and adult emergence inhibition may be associated with constituents in both plants that interfere with the normal neuronal, respiratory and endocrine systems functions.

Chemical Composition, Larvicidal and Adult Emergence Inhibition Activities of Balanites aegyptiaca Del. Seed and Aristolochia albida Duch. Root Extracts against Malaria Vector, Anopheles gambiae Giles

Background: Anopheles gambiae is enemy number one of mankind in Africa and particularly in Cameroon due to its ability of transmitting malaria which is the deadliest disease in this part of the world. Synthetic insecticides have been used to control malaria vectors but they have negative effects on non-target organisms and are environmentally unfriendly. Control of mosquitoes at larval stages using phytochemicals is currently the leading tool to reduce the mosquito population and so the reduction of malaria transmission rates. Therefore, the present study was to evaluate the phytochemical contents, larvicidal and adult emergence inhibition activities of Balanites aegyptiaca seed and Aristolochia albida root solvents extracts against Anopheles gambiae larvae. Methods: The World Health Organization standard protocols were followed for the different bioassays. Concentrations ranging from 500 - 2000 ppm for larvicidal and 500 - 1500 ppm for IGRs were used. Results: Both plants showed the presence of alkaloids, flavonoids, saponins, tannins, phenols, terpenoids and oils except the absence of phenols in Aristolochia albida. The larvicidal activity of Aristolochia albida extracts showed that hexane and methanol fractions were the most active killing relatively all exposed larvae with the LC50 values of 420.1 and 453 ppm, respectively. The same observation was made in hexane fraction from Balanites aegyptiaca (LC50 = 588 ppm). The insect growth inhibitory activity of Aristolochia albida extracts proved that hexane and methanol fractions relatively caused a 100% inhibition in the mosquito development, recording the EI50 values of 482.4 and 555.6 ppm, respectively. The same trend was observed with Balanites aegyptiaca hexane fraction registering better EI50 of 623.9 ppm. Conclusions: Our findings demonstrate that Balanites aegyptiaca seed and Aristolochia albida seed extracts are rich in phytochemicals capable of killing mosquito larvae and disrupting mosquito larval development. This could contribute to the control of mosquito populations and improved management of malaria.

Impact of Urban Agriculture on the Species Distribution and Insecticide Resistance Profile of <i>Anopheles gambiae s.s.</i>and <i>Anopheles coluzzii</i>in Accra Metropolis, Ghana

Malaria incidence in urban areas has generally been low compared to rural areas but recent data indicate that urban malaria remains a public health problem. It is therefore important to understand the factors that promote urban malaria to help formulate future vector control strategies. This study compared Anopheles gambiae s.l. (A. gambiae s.l.) species composition, distribution and insecticide resistance mechanisms between vegetable and non-vegetable growing areas in Accra Metropolis. Four sites were selected within the city of Accra which comprised of two vegetable-growing and two non-vegetable growing areas. WHO susceptibility tests were carried out on adults A. gambiae s.l. reared from larvae collected from the sites. Five insecticides were tested and the A. gambiae complex, resistance genotypes and enzyme activities of each population were characterized. All A. gambiae s.l. populations tested were resistant to all the insecticides, but relatively lower mortalities were observed in the vegetable growing areas. The mortality against 0.05% deltamethrin was 2.6% (Opeibea) and 12.5% (Korle-Bu) for the vegetable growing areas and 36.2% (Achimota) and 38.9% (Mataheko) in the non-vegetable growing areas. Anopheles gambiae s.s. (95% of Opeibea population) and Anopheles coluzzii, (98% of Korle-Bu population) were the dominant species in the vegetable growing areas. The voltage-gated sodium channel (Vgsc-1014F) frequencies of all the populations were similar but the acetylcholinesterase (ace-1) frequencies were significantly lower (p A. gambiae s.l. from Opeibea than from the other areas. The contribution of urban agriculture in the development of insecticide resistance needs to be considered in the formulation of future vector control strategies alongside other domestic usages.

A Preliminary Investigation of Smart Rural Water Distribution Systems in the Gambia

An estimated one-third of water points in rural sub-Saharan Africa are non-functioning at any one time because of lack of upkeep. Communities are left without access to clean drinking water and this has multiple knock-on developmental impacts. An innovative pre-payment and Internet-of-Things enabled “e-Tap” based water technology and management system cycles revenue back into operation and maintenance and collects accurate and real-time data on consumption and tap failures. This has been operational in the Gambia since April 2016. Preliminary research has begun on evaluating this innovation. Technical tests were conducted to examine the efficiency of the e-Tap under varying conditions. Water use trends were then analysed by using the cloud-collected data transmitted from operational e-Taps. Further, baseline sveys to investigate social parameters were undertaken on 20 user households. This exploratory research shows the e-Taps to work efficiently in the laboratory and the Gambia with negligible failures, and to reduce distances users must travel for clean water and time they spend collecting.

An Integrated Optimal Approach for Solar Powered Rural Water Distribution Systems in the Gambia

In the Gambia and across sub-Saharan Africa, reliable access to clean water and electrical power is constrained. As most rural water supply systems are built, enhanced understanding of efficiencies and optimisation is required. Here, methods of integrating estimations of power outputs from solar photovoltaic arrays into gravity-fed water distribution network modelling are investigated. The effects of powering a rural water distribution system that is replenished with groundwater pumps that use solar power are investigated, along with the effect of this on other network design decisions. The water storage tank and pipework of a rural community with an estimated 2800 people and 28 standpipes from a borehole was selected. EPANET modelling software and genetic algorithms were used to run network optimisation simulations of: water tank location, elevation and volume;pipe diameter and configuration;and optimal system design in terms of cost. Different scenarios were produced, including supply, demand and required water storage curves, which could have practical application for rural water distribution system design. Indicative costs for theoretical water distribution networks will be useful for decision makers and planners.

Larvicidal efficacy of monoterpenes against the larvae of Anopheles gambiae

Objective:To evaluate the larvicidal efficacy of eight volatile components of essential oils against 3rd instar larvae of Anopheles gambiae s.s.Methods:Larvicidal effects of each compound were evaluated in both laboratory and semi-field trials.Stock solution was prepared and serial dilutions were made in six concentrations for each compound.A total of 20 larvae were exposed to larvicides for each replicate and monitored at intervals of 12,24,48 and 72 h.Larvae monitoring was done on basis of dead and live larvae in all intervals.Results:All assayed compounds were larvicides and presented varying degrees of larval toxicity,with LC50 values ranging from 1.28 to 1 938.92 mg/L depending on the treatment time(12,24,48 or 72 h).(-)-Perillyl alcohol presented the strongest larvicidal activity towards Anopheles gambiae larvae,with LC_(50) values of 73.60,18.36,1.72 and1.28 mg/L after 12,24,48 and 72 h of exposure,respectively.The next strongest were(-)-isopulegol(LC_(50)= 135.10,49.39,34.39 and 20.22 mg/L) and(-)-carvone epoxide(LC_(50)= 168.86,124.74,80.84 and 23.46 mg/L).After 12,24 and 48 h of treatment,hydroxydihydrocarvone was the least toxic compound,with LC_(50) values of 1 938.92,1 172.18 and 401.03 mg/L,respectively.Conclusions:The data obtained in this study suggest that all evaluated monoterpenes,especially(-)-perillyl alcohol,have remarkable larvicidal effects and may be considered as potential sources for the development of suitable natural larvicides for mosquito management programs.Further small-scale field trials should be conducted.

Anopheles gambiae larvicidal and adulticidal potential of Phyllanthus amarus(Schumach and Thonn,1827)obtained from different localities of Nigeria

Objective:To screen phytochemicals in ethanolic leaf extracts of Phyllanthus amarus collected from three different geographical zones in Nigeria and evaluate their effects on larva and adult of Anopheles gambiae.Methods:The sample extracts of Phyllanthus amarus prepared with ethanol solvent were tested against Anopheles gambiae at two important developmental stages of its life cycle using slightly modified WHO protocols.Results:Alkaloids,saponins,tannins,flavonoids,glycosides,phenols,and terpenes were detected in each extract.Among these samples,the extract from northwest exhibited the highest larvicidal activity(LC50=263.02 ppm),followed by southeast and southwest extracts(LC50=288.40 and 295.12 ppm,respectively after 48 h),while the extract from southwest exhibited the highest adulticidal activity(LC50=275.42 ppm),followed by northwest and southeast extract(LC50=301.99 and 316.22 ppm,respectively after 24 h).A 50%larva mortality was almost attained at 600 ppm after 48 h duration of exposure to the northwest extract.Conclusions:The tested samples possess strong larvicidal and adulticidal property against Anopheles gambiae which depends on their chemical composition and localities of collection.Further studies are needed to explore the insecticidal activity against a wider range of mosquito species,and to identify active ingredient(s)of the extract responsible for such activity.

Biogenic Synthesis of Silver Nanoparticles Using Guava (<i>Psidium guajava</i>) Leaf Extract and Its Larvicidal Action against <i>Anopheles gambiae</i>

The progress in the field of nanotechnology has contributed to the development of tools for combating the most critical problems in developing countries. The requirements that such tools should meet are low-cost and resource settings, environmental protection, ease of use, and availability. The use of plant properties for the generation of nanoparticles (NPs), which serve as bioinsecticides to combat the plasticity and resistance of mosquitoes and parasites, is considered possible. Here, we report for the first time the larvicidal activity of silver (Ag) NPs (AgNPs) synthesized from Psidium guajava (P. guajava) extract, which targets the 4th instar larvae of Anopheles gambiae. Concentrations of AgNPs between 0 and 200 ppm were used and their LC50 at 24 h and 48 h were determined as 19.55 ppm and 8.737 ppm, respectively. The AgNPs were stable and highly effective against the larvae of A. gambiae and thereby we anticipate that they can be used to combat vector-borne diseases in developing countries.

Fine-scale evolutionary genetic insights into Anopheles gambiae X-chromosome

Understanding the genetic architecture of indi-vidual taxa of medical importance is the first step for designing disease preventive strategies. To understand the genetic details and evolu-tionary perspective of the model malaria vector, Anopheles gambiae and to use the information in other species of local importance, we scanned the published X-chromosome se-quence for detail characterization and obtain evolutionary status of different genes. The te-locentric X-chromosome contains 106 genes of known functions and 982 novel genes. Majori-ties of both the known and novel genes are with introns. The known genes are strictly biased towards less number of introns;about half of the total known genes have only one or two in-trons. The extreme sized (either long or short) genes were found to be most prevalent (58% short and 23% large). Statistically significant positive correlations between gene length and intron length as well as with intron number and intron length were obtained signifying the role of introns in contributing to the overall size of the known genes of X-chromosome in An. gam-biae. We compared each individual gene of An. gambiae with 33 other taxa having whole ge-nome sequence information. In general, the mosquito Aedes aegypti was found to be ge-netically closest and the yeast Saccharomyces cerevisiae as most distant taxa to An. gambiae. Further, only about a quarter of the known genes of X-chromosome were unique to An. gambiae and majorities have orthologs in dif-ferent taxa. A phylogenetic tree was constructed based on a single gene found to be highly orthologous across all the 34 taxa. Evolutionary relationships among 13 different taxa were in-ferred which corroborate the previous and pre-sent findings on genetic relationships across various taxa.

Maternal and obstetric risk factors for low birth weight and preterm birth in rural Gambia: a hospital-based study of 1579 deliveries

Introduction: Low birth weight and prematurity are risk factors for perinatal morbidity and mortality, which is high in Sub Saharan African countries. We determined the frequency of and maternal and obstetric risk factors for low birth weight and preterm birth among hospital births in rural Gambia. Method: We performed a hospital-based retrospective analysis of deliveries from July to December 2008 in two rural hospitals. Maternity records were reviewed and abstracted of the mother’s demographic and reproductive characteristics, obstetric complications and foetal outcome. The maternity records contain important information maternal health and complications during pregnancy and intrapartum period. The records also contain information about the newborn’s vital status and birth weight. To determine the association between low birth weight (LBW), preterm birth (PTB) and maternal demographic characteristics and obstetric complications we calculated odds using logistic regression. Main outcome measure(s): Low birth weight (<2500 grams) and preterm birth (<37 weeks). Results: Our final sample included 1244 singleton live births with complete information about all variables. The rate of LBW and PTB were 10.5% and 10.9% respectively. Ninety-four percent of LBW infants were estimated to be preterm births. The mean birth weight was 3013 g (541 g standard deviation-SD), while the mean gestational age was 37 weeks. The pattern of risk factors was similar for LBW and PTB and both were strongly associated with antepartum haemorrhage and hypertensive pregnancy disorders. Additionally, primi parity was a risk factor for both PTB and LBW. Conclusion: The percentage of low birth weight and preterm birth in rural hospitals in The Gambia is high. The most significant risk factors were those that may be detected during the antepartum period. Thus, vigilant monitoring during pregnancy, early detection and management of obstetric complications coupled with provision of timely obstetric care interventions are crucial for

The molecular mechanism for DDT detoxification in Anopheles gambiae: A molecular docking study

The epsilon class glutathione-S-transferase of Anopheles gambiae, agGSTe2, is capable of metabolizing DDT. A molecular docking analysis of DDT with agGSTe2 support an E2 elimination mechanism wherein the glutathione sulfur serves as the base to convert DDT to DDE.

Qualitative Detection of Proviral-DNA of HIV-1 in Infants to Determine the Efficacy of Antiretroviral Therapy in the Prevention of Vertical Transmission of HIV-1 in The Gambia

The priority of The Gambia government is to eliminate maternal to child transmission of HIV and in line with this priority, the country implemented an antiretroviral therapy (ART) program. With this, all HIV infected pregnant and breastfeeding mothers and infants have access to ARV drugs. This study aims to determine the prevalence of vertical transmission of HIV among women receiving the ARV drugs. Dried blood spot samples were collected from 109 HIV-exposed infants enrolled in 13 PMTCT sites across the country. A qualitative detection of proviral-DNA of HIV-1 was performed using the RealTime Abbott PCR assay. Data from 105 mothers were analyzed using SPSS version 16.0 and association of risk factors to PCR results were analyzed using (Crosstabs) Pearson Chi-Square. The p-value of significant was set at p < 0.05. This study has found that the prevalence of vertical transmission of HIV is 0.0% (0/64) among women that received the ARV prophylaxis then started ART, 7.1% (2/28) among mothers that received HIV prophylaxis only, and 38.4% (5/13) among women who neither receive HIV-prophylaxis nor ART during pregnancy or breastfeeding. Other risk factors of vertical transmission such as late initiation of treatment, default during treatment and first born of twins were found to be significantly associated with vertical transmission p = 0.001, p = 0.022 and p = 0.000 respectively. This study has found that the early intervention of ART at the onset of pregnancy through breastfeeding can eliminates Maternal to Child transmission of HIV-1and a high risk of vertical transmission was found among women who neither receive prophylaxis nor ART. If the effectiveness of the antiretroviral therapy is maintain, The Gambia, in the near future will attain the WHO’s goal to eliminate maternal to child transmission of HIV.

Efficacy of the Microbial Larvicide VectoMax^®G against <i>Anopheles gambiae</i>s.l. and <i>Culex</i>spp. Larvae under Laboratory and Open Field Trial Experiments in the City of Yaoundé, Cameroon

Background: With the rapid expansion of insecticide resistance limiting the effectiveness of insecticide-based vector control interventions, integrated control strategies associating larviciding could be appropriate to improve current control efforts. The present experimental study assesses laboratory and field efficacy of the larvicide VectoMax®G on Anopheline and Culicine larval stages in Yaoundé. Methods: The effect of the larvicide VectoMax®G, a combination of Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs), on larval development was assessed during both laboratory and open field trial experiments. Laboratory experiments permitted the evaluation of five different concentrations with four replicates/experiments. Laboratory experiments were conducted with Anopheles coluzzii “Ngousso” and Culex quinquefasciatus laboratory strains. Open field trials were conducted using sixteen plastic containers with a diameter of 0.31 m buried in an array of four rows with 4 containers each. Distance between rows and between containers in a row was 1 meter. This experiment permitted to test the effect of the microbial larvicide VectoMax®G under operational application conditions on field mosquito populations. Results: The time to induce 100% mortality after exposure to serial concentrations of the larvicide varied according to the dose from 4 - 12 hours for An. coluzzii and 6 - 9 hours for Cx. quinquefasciatus in laboratory experiments. Measurements of the residual activity indicated that all VectoMax®G concentrations were still active after 35 days and killed 86% - 100% of larvae. Lethal dose of VectoMax®G killing 50% of larvae was estimated at 5.24 × 10-8 mg/m2 for An. coluzzii and 1.25 × 10-8 mg/m2 for Cx. quinquefasciatus. The lethal concentration inducing 95% mortality was estimated at 3.13 × 10-7 mg/m2 for An. coluzzii and 2.5 × 10-8 mg/m2 for Cx. quinquefasciatus. Open field trials tests indicated that sub-lethal concentrations of VectoMax®G successfully killed 100% An. gambiae s.l. larvae within 24 hours, while with Culex spp. larvae, 100% mortality was recorded after 48 hours post-treatment. Natural recolonization of water containers by larvae was recorded between 3 and 6 days respectively after the treatment with sublethal doses. Late instar larvae were recorded 5 and 6 days after treatment. When the jars were treated with reference dosage or supra doses of VectoMax®G, recolonization of water containers was observed six days after treatments. No pupae of both species were found 6 and 7 days post-treatment. Conclusions: The study indicated high efficacy of the microbial larvicide VectoMax®G against Anopheline and Culex larvae. Microbial larvicides such as VectoMax®G could be appropriate for controlling mosquito population particularly in areas experiencing high insecticide resistance or outdoor biting mosquitoes.

Laboratory Growth of <i>Anopheles gambiae</i>(Diptera: Culicidae) and Morphological Determinism of Moulting

Growth in arthropods in general and in insects in particular, is supposed to be discontinuous and occurs during moulting. In Culicidae in general and Anopheles in particular, the number of moults is five with the fourth which gives the pupae. It is known that moulting in insects is a genetic and physiological phenomenon. Most physiological reactions are triggered by chemical or physical stimuli. The pressure exerted by the growth of the larval body on the exocuticle is one of the triggers of moulting. The objective of this work was therefore to determine the exact timing of the first three moults that determine the growth of An. gambiae larvae from egg hatch to pupation to highlight the role of increased larval size in the stimulation of moulting. We therefore, undertook to rear larvae of this anopheline species in the laboratory under conditions close to their natural environment from hatching to pupation. The length and width of the head, thorax and abdomen were recorded daily. Data analysis showed that the size of the head and thorax remained constant for the first three days (D0 to D2) of development and abdomen’s length for the first two days and then increased daily until day seven (D7) when it stopped. These observations led us to say that the M1 moult occurs at end of the third day of development and the M3 moult at end of the eighth day;the M2 moult could not be determined. All these observations led to the conclusion that the larval growth of An. gambiae has a continuous regimen and the growth of the head and thorax of the larva plays a crucial role in the onset of moulting.

Identification and expression profiling of putative odorant-binding proteins in the malaria mosquitoes, Anopheles gambiae and A. arabiensis

Olfaction plays a major role in host-seeking behaviour of mosquitoes. An informat- ics-based genome-wide analysis of odorant-binding protein (OBP) homologues is under- taken, and 32 putative OBP genes in total in the whole genome sequences of Anopheles gam- biae are identified. Tissue-specific expression patterns of all A. gambiae OBP candidates are determined by semi-quantitative Reverse Transcription (RT)-PCR using mosquito actin gene a internal expression control standard. The results showed that 20 OBP candidates had strong expression in mosquito olfactory tissues (female antennae), which indicate that OBPs may play an important role in regulating mosquito olfactory behaviours. Species-specific expression pat- terns of all putative anopheline OBPs are also studied in two of the most important malaria vec- tors in A. gambiae complex, i.e. A. gambiae and A. arabiensis, which found 12 of the putative OBP genes examined displayed species-differential expression patterns. The cumulative relative expression intensity of the OBPs in A. arabiensis antennae was higher than that in A. gambiae (the ratio is 1441.45:1314.12), which might be due to their different host preference behaviour. While A. gambiae is a highly anthropophilic mosquito, A. arabiensis is more opportunistic (Vary- ing from anthropophilic to zoophilic). So the latter should need more OBPs to support its host selection preference. Identification of mosquito OBPs and verification of their tissue- and spe- cies-specific expression patterns represent the first step towards further molecular analysis of mosquito olfactory mechanism, such as recombinant expression and ligand identification.

Bioinformatics-Based Identification of Chemosensory Proteins in African Malaria Mosquito, Anopheles gambiae

Chemosensory proteins (CSPs) are identifiable by four spatially conserved Cys-teine residues in their primary structure or by two disulfide bridges in their tertiary structure according to the previously identified olfactory specific-D related proteins. A genomics- and bioinformatics-based approach is taken in the present study to identify the putative CSPs in the malaria-carrying mosquito, Anopheles gambiae. The results show that five out of the nine annotated candidates are the most possible Anopheles CSPs of A. gambiae. This study lays the foundation for further functional identification of Anopheles CSPs, though all of these candidates need additional experimental verification.

Biochemical characterization of chitin synthase activity and inhibition in the African malaria mosquito, Anopheles gambiae

Chitin synthase （CHS） is an important enzyme catalyzing the formation of chitin polymers in all chitin containing organisms and a potential target site for insect pest control. However, our understanding of biochemical properties of insect CHSs has been very limited. We here report enzymatic and inhibitory properties of CHS prepared from the African malaria mosquito, Anopheles gambiae. Our study, which represents the first time to use a nonradioactive method to assay CHS activity in an insect species, determined the optimal conditions for measuring the enzyme activity, including pH, temperature, and concentrations of the substrate uridine diphosphate N-acetyl-D-glucosamine （UDP- GlcNAc） and Mg＋＋. The optimal pH was about 6.5-7.0, and the highest activity was detected at temperatures between 37℃ and 44℃. Dithithreitol is required to prevent melanization of the enzyme extract. CHS activity was enhanced at low concentration of GIcNAc, but inhibited at high concentrations. Proteolytic activation of the activity is significant both in the 500×g supernatant and the 40 000×g pellet. Our study revealed only slight in vitro inhibition ofA. gambiae CHS activity by diflubenzuron and nikkomycin Z at the highest concentration （2.5μmol/L） examined. There was no in vitro inhibition by polyoxin D at any concentration examined. Furthermore, we did not observe any in vivo inhibition of CHS activity by any of these chemicals at any concentration examined. Our results suggest that the inhibition of chitin synthesis by these chemicals is not due to direct inhibition of CHS in A. gambiae.

New selenoproteins identified in silico from the genome of Anopheles gambiae

Selenoprotein is biosynthesized by the incorporation of selenocysteine into proteins,where the TGA codon in the open reading frame does not act as a stop signal but is translated into selenocysteine.The dual functions of TGA result in mis-annotation or lack of selenoproteins in the sequenced genomes of many species.Available computational tools fail to correctly predict selenoproteins.Thus,we devel-oped a new method to identify selenoproteins from the genome of Anopheles gambiae computationally.Based on released genomic information,several programs were edited with PERL language to identify selenocysteine insertion sequence(SECIS)element,the coding potential of TGA codons,and cys-teine-containing homologs of selenoprotein genes.Our results showed that 11365 genes were termi-nated with TGA codons,918 of which contained SECIS elements.Similarity search revealed that 58 genes contained Sec/Cys pairs and similar flanking regions around in-frame TGA codons.Finally,7 genes were found to fully meet requirements for selenoproteins,although they have not been anno-tated as selenoproteins in NCBI databases.Deduced from their basic properties,the newly found se-lenoproteins in the genome of Anopheles gambiae are possibly related to in vivo oxidation tolerance and protein regulation in order to interfere with anopheles' vectorial capacity of Plasmodium.This study may also provide theoretical bases for the prevention of malaria from anopheles transmission.

Anopheles gambiae strain(Ag55)cultured cells originated from Anopheles coluzzii and are phagocytic with hemocyte-like gene expression

Anopheles gambiae and Anopheles coluzzii are closely related species that are predominant vectors of malaria in Africa.Recently,A.gambiae form M was renamed A.coluzzii and we now conclude on the basis of a diagnostic PCR-restriction fragment length polymorphism assay that Ag55 cells were derived from A.coluzzii.We established an Ag55 cell transcriptome,and KEGG pathway analysis showed that Ag55 cells are enriched in phagosome pathway transcripts.The Ag55 transcriptome has an abundance of specific transcripts characteristic of mosquito hemocytes.Functional E.coli bioparticle uptake experiments visualized by fluorescence microscopy and confocal microscopy and quantified by flow cytometry establish the phagocytic competence of Ag55 cells.Results from this investigation of Ag55 cell properties will guide researchers in the use and engineering of the Ag55 cell line to better enable investigations of Plasmodium,other microbes,and insecticidal toxins.

Ecdysis triggering hormone peptide in the African malaria mosquito Anopheles gambiae:The peptide structure for receptor activation

Infections by mosquito-borne diseases represent one of the leading causes of death in third world countries.The rapid progression of resistance to conventional insecticide causes a significant threat to the highly efficient preventive methods currently in place.Insect neuropeptidergic system offers potential targets to control the insect vectors.The essential roles of the neuropeptide ecdysis triggering hormone(ETH)in insect development and reproduction led us to attempt understanding of the fundamentals of the biochemical interaction between ETH and its receptor in the African malaria mosquito Anopheles gambiae.One of two ETH peptides of the African malaria mosquito(AgETH1),a small peptide hormone with 17 amino acid residues(SESPGFFIKLSKSVPRI-NH2),was studied to elucidate its molecular structure.N-termini deletions and mutations of conserved amino acids in the ligand revealed the critical residues for the receptor activation.The solution structure of AgETH1 using 2D 1H-1H nuclear magnetic resonance(NMR)spectroscopy and nuclear overhauser effect(NOE)derived constraints revealed a short alpha helix between residues 3S and 11S.The NMR solution structure of AgETH1 will be of significant assistance for designing a new class of insecticidal compounds that acts on the AgETH receptor aiming for in silico docking studies.