RESUMEN
Herbivorous insects use detoxification enzymes, including cytochrome P450 monooxygenases, glutathione S-transferases, and carboxy/cholinesterases, to metabolize otherwise deleterious plant secondary metabolites. Whereas Acyrthosiphon pisum (pea aphid) feeds almost exclusively from the Fabaceae, Myzus persicae (green peach aphid) feeds from hundreds of species in more than forty plant families. Therefore, M. persicae as a species would be exposed to a greater diversity of plant secondary metabolites than A. pisum, and has been predicted to require a larger complement of detoxification enzymes. A comparison of M. persicae cDNA and A. pisum genomic sequences is partially consistent with this hypothesis. There is evidence of at least 40% more cytochrome P450 genes in M. persicae than in A. pisum. In contrast, no major differences were found between the two species in the numbers of glutathione S-transferases, and carboxy/cholinesterases. However, given the incomplete M. persicae cDNA data set, the number of identified detoxification genes in this species is likely to be an underestimate.
Asunto(s)
Áfidos/enzimología , Áfidos/genética , Genoma de los Insectos , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Biotransformación/genética , Hidrolasas de Éster Carboxílico/genética , Hidrolasas de Éster Carboxílico/metabolismo , Colinesterasas/genética , Colinesterasas/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Cartilla de ADN/genética , ADN Complementario/genética , Evolución Molecular , Etiquetas de Secuencia Expresada , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Datos de Secuencia Molecular , Pisum sativum/metabolismo , Pisum sativum/parasitología , Filogenia , Prunus/metabolismo , Prunus/parasitología , Homología de Secuencia de Aminoácido , Especificidad de la EspecieRESUMEN
We used an expressed sequence tag and 454 pyrosequencing approach to initiate a study of the genome of the screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae). Two normalized cDNA libraries were constructed from RNA isolated from embryos and second instar larvae from the Panama 95 strain. Approximately 5,400 clones from each library were sequenced from both the 5' and 3' directions using the Sanger method. In addition, double-stranded cDNA was prepared from random-primed polyA RNA purified from embryos, second-instar larvae, adult males, and adult females. These four cDNA samples were used for 454 pyrosequencing that produced approximately 300,000 independent sequences. Sequences were assembled into a database of assembled contigs and singletons and used to search public protein databases and annotate the sequences. The full database consists of 6,076 contigs and 58,221 singletons assembled from both the traditional expressed sequence tag (EST) and 454 sequences. Annotation of the data led to the identification of several gene coding regions with possible roles in sex determination in the screwworm. This database will facilitate the design of microarray and other experiments to study screwworm gene expression on a larger scale than previously possible.
Asunto(s)
Dípteros/genética , Etiquetas de Secuencia Expresada , Procesos de Determinación del Sexo , Secuencia de Aminoácidos , Animales , Bases de Datos Genéticas , Femenino , Genes de Insecto , Masculino , Datos de Secuencia MolecularRESUMEN
Alcaligenes xylosoxydans protected pigeonpea from Fusarium wilt in a pot experiment and field trials. When seeds of pigeonpea (C. cajan) were treated with A. xylosoxydans and sown in soil infested with Fusarium, the incidence of wilt was reduced by 43.5% and resulted in 58% higher grain yield. The antifungal activity of A. xylosoxydans was based on chitinase production and was comparable in efficacy to commercial antifungal agents such as benlate, monitor WP, thiram and bavistin.
Asunto(s)
Alcaligenes/fisiología , Cajanus/crecimiento & desarrollo , Quitina/metabolismo , Fusarium/fisiología , Control Biológico de Vectores , HidrólisisRESUMEN
AIMS: To develop a novel, rapid and effective screening method for chitinase producing bacteria. METHODS AND RESULTS: A simple and rapid technique for screening of potential chitinolytic bacteria has been developed using the chitin binding dye calcofluor white M2R in chitin agar. Microorganisms possessing high chitinolytic potential gave a clear zone under ultraviolet light after 24-48 h of incubation. This method was successfully applied for isolating the hyperchitinase mutant of Alcaligenes xylosoxydans. The mutant Alc. xylosoxydans EMS 33 was found to produce 3.4 times more chitinase than the wild type. CONCLUSIONS: In this study, the screening method for chitinase producing bacteria has been developed and it was applied to screen chitinase-overproducing mutant of Alc. xylosoxydans. SIGNIFICANCE AND IMPACT OF THE STUDY: The novel screening method for chitinase producer is more sensitive, rapid, user-friendly and reliable, which can also be used for screening of recombinants having chitinase gene.