Home About us Contact
|
Home About us Contact | ||
|
|
||
Yellow Fever Mosquito (yellow + fever_mosquito)
Selected AbstractsHigh efficiency site-specific genetic engineering of the mosquito genomeINSECT MOLECULAR BIOLOGY, Issue 2 2006D. 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] Germ line transformation of the yellow fever mosquito, Aedes aegypti, mediated by transpositional insertion of a piggyBac vectorINSECT MOLECULAR BIOLOGY, Issue 2 2002N. 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] Molecular cloning of two prophenoloxidase genes from the mosquito Aedes aegyptiINSECT MOLECULAR BIOLOGY, Issue 1 2001A. 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 aegyptiINSECT MOLECULAR BIOLOGY, Issue 1 2000N. 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] In vivo and in vitro activity of venom from the endoparasitic wasp Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2006Ekrem Ergin Abstract The biological activity of venom from Pimpla turionellae L. (Hymenoptera: Ichneumonidae) was examined in vivo toward larvae and pupae of Galleriae mellonella L. (Lepidoptera: Pyralidae), and in vitro toward bacterial and fungal cultures, as well as cultured insect cells. Pupae of G. mellonella were far more susceptible to the venom than larvae. At low doses of venom [0.1 venom reservoir equivalents (VRE)], pupal abdominal mobility was inhibited within 30 min, and by 24 h, all pupae injected with venom concentrations >0.5 VRE were completely paralyzed. These same doses of venom resulted in an inhibition of adult emergence. Host larvae were far less sensitive to wasp venom as evidenced by all venom injected larvae remaining responsive to mechanical stimulation by 1 h post injection, even at concentrations equivalent to 1 venom reservoir. Eventually (>2 h at 25°C), venom-injected larvae became immobile, then flaccid, and all died within 24 h post-injection. At lower concentrations of wasp venom, the onset of paralysis was delayed by comparison to that evoked by 1 VRE, and few host larvae were able to pupate. Development of host larvae to adult emergence was also reduced in a dose-dependent manner, with eclosion completely prevented at high concentrations (>0.5 VRE) of venom. Venom doses <0.5 VRE did not appear to induce paralysis or alter larval development. When venom was incubated with bacterial or fungal cultures, no antimicrobial activity was detected. However, wasp venom was found to be cytotoxic and cytolytic to cultured cells derived from the cabbage looper Trichoplusia ni Hubner (Lepidoptera: Noctuidae) and the yellow fever mosquito, Aedes aegypti (L.) (Diptera: Culcidae). Though both cell types displayed similar susceptibility in terms of LC50s, the lepidopteran cells responded much more rapidly with regard to the onset of morphological changes and the timing of cell death. A possible mode of action for the venom is discussed. Arch. Insect Biochem. Physiol. 61:87,97, 2006. © 2006 Wiley-Liss, Inc. [source] Repellent studies with Aedes aegypti mosquitoes and human olfactory tests on 19 essential oils from Corsica, FranceFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2009J. Drapeau Abstract In order to reduce the risk of getting infected with any epidemic disease transmitted by mosquitoes, repellent products are often used to protect populations at risk. The repellent potential of 19 essential oils from the island of Corsica, France, was evaluated in a bio-assay with the mosquito Aedes aegypti, in order to assess the ,space repellent' properties of these oils. Lavendula stoechas, Helichrysum italicum (leaves) and Laurus nobilis oils showed a capability of reducing the attractivity of a human finger for yellow fever mosquitoes in a Y-tube olfactometer. In addition to the behavioural studies on mosquitoes, two tests on the olfactory perception of these 19 oils were performed, involving 25 female and 25 male human volunteers. The aspects studied were the ,hedonic dimension' of these oils and their acceptance as a final fragrance for a repellent formulation. The experiments yielded promising results concerning both aspects for three oils, from Calamintha nepeta, Laurus nobilis and Rosmarinus officinalis, with minor differences between male and female participants. Laurus nobilis oil was the only oil tested fulfilling both properties: a spatial repellent effect on Aedes aegypti and acceptance by the volunteers for its integration in a repellent product. Thermogravimetric analysis showed that Calamintha nepeta oil has a slower evaporation rate in comparison to the Laurus nobilis and Rosmarinus officinalis oils. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||