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Esterase Genes (esterase + gene)
Selected AbstractsEsterase-based resistance in the tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) in the eastern United StatesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009Lakshmipathi Srigiriraju Abstract Organophosphates and carbamates represent alternative insecticides in managing the tobacco-adapted form of the green peach aphid (TGPA), Myzus persicae (Sulzer), a major pest of tobacco in the United States and around the world. General esterases that detoxify these insecticides were assessed in green, red, and orange morphs of field-collected M. persicae. A total of 136 aphid colonies were collected from 2004 though 2007 and screened for total esterase activity. The green morphs had lower esterase levels, with a mean of 77±6.6,nmol/min/mg protein, as compared to red (84±2.9,nmol/min/mg protein) and orange morphs (172±16.5,nmol/min/mg protein). Overall esterase activities, and those for the red and green morphs, were positively correlated with LC50 values for acephate (organophosphate) and methomyl (carbamate) assessed in leaf-dip bioassays. Esterase genes responsible for higher esterase activities were diagnosed by gene amplification studies. Twenty-three of 24 colonies tested had either the E4 or FE4 gene amplified, both known to confer esterase-based resistance. Fifteen out of the 24 colonies tested had amplified E4 gene and four colonies had FE4 gene amplification. All orange morphs and one green morph had both E4 and FE4 genes amplified. This unique phenotype, where two esterase genes were amplified had an 865-bp band characteristic of the FE4 gene and an additional 381-bp band characteristic of a deleted upstream region of the E4 gene. Changes that occurred in esterase-based resistance in the TGPA over the past two decades and their implications on insecticide resistance management are discussed. © 2009 Wiley Periodicals, Inc. [source] Cloning and expression of a Melanocarpus albomyces steryl esterase gene in Pichia pastoris and Trichoderma reeseiBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2006Hanna Kontkanen Abstract The ste1 gene encoding a steryl esterase was isolated from the thermophilic fungus Melanocarpus albomyces. The gene has one intron, and it encodes a protein consisting of 576 amino acids. The deduced amino acid sequence of the steryl esterase was shown to be related to lipases and other esterases such as carboxylesterases. Formation of mature protein requires post-translational removal of a putative 18-amino-acid signal sequence and a 13-residue propeptide at the N-terminus. The intronless version of the Melanocarpus albomyces ste1 gene was expressed in Pichia pastoris under the inducible AOX1 promoter. The production level was low, and a large proportion of the total activity yield was found to be present intracellularly. However, the fact that steryl esterase activity was produced by P. pastoris cells carrying the expression cassette confirmed that the correct gene had been cloned. The ste1 gene was subsequently expressed in T. reesei under the inducible cbh1 promoter, and a clearly higher production level was obtained. About 60% of the total activity was bound to the fungal mycelium or to solid components of the culture medium, or existed as aggregates. Triton X-100 was successfully used to recover this activity. The heterologous production system in T. reesei provides a means of producing M. albomyces steryl esterase STE1 reliably in large scale for future studies. © 2006 Wiley Periodicals, Inc. [source] Molecular characterization of two novel esterase genes from carmine spider mite, Tetranychus cinnabarinus (Acarina: Tetranychidae)INSECT SCIENCE, Issue 2 2010Wei Sun Abstract, Two novel esterase complementary DNAs were identified and cloned from the insecticide-susceptible strain of Tetranychus cinnabarinus (Boisduval) (Acarina: Tetranychidae), which were designated as TCE1 and TCE2, respectively. The cDNA of TCE1 gene contained an open reading frame (ORF) of 1701 bp encoding 567 amino acids, and a predicted molecular weight of 62.75 kDa, the cDNA of TCE2 contained an ORF of 1680 bp encoding 560 amino acids, and a predicted molecular weight of 63.14 kDa. TCE1 and TCE2 were submitted to GenBank, accession number EU130461 and EU130462. The well-conserved sequence motif, GXSXG, used as a signature pattern in the esterase family are present in both TCE1 and TCE2 (GQSAG in TCE1, whereas GESAG in TCE2), indicating that these two genes are predicted to be esterases. Comparison of the deduced amino acid sequence with the published mite esterase sequence coming from Boophilus microplus showed that TCE1 shares 33.98% identity and TCE2 shares 33.46% identity. TCE1 and TCE2 share 46.4% identity. Quantitative real-time polymerase chain reaction revealed that expression level of the TCE2 gene was relatively higher than that of the TCE1 in all instars examined except the protonymph, and the expression level of these two esterase genes in adults of T. cinnabarinus was significantly higher than that in any other instars, respectively. T. cinnabarinus is an important agricultural mite pest and esterases are important in the metabolisms of insects and mites; the genomic information obtained in this study will contribute to esterase molecular biological study on mite pest species. [source] Characterization of four esterase genes and esterase activity from the gut of the termite Reticulitermes flavipesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2010Marsha M. Wheeler Abstract Four esterase genes and general esterase activity were investigated in the gut of the termite Reticulitermes flavipes. Two genes (RfEst1 and RfEst2) share significant translated identity with a number of insect JH esterases. The two remaining genes (RfEst3 and RfEst4) apparently code for much shorter proteins with similarity to fungal phenolic acid esterases involved in hemicellulose solubilization. All four genes showed consistently high midgut expression. This result was further supported by colorimetric activity assays and Native polyacrylamide gel electrophoresis, which showed significant esterase activity and a number of isoforms in the midgut. The greatest esterase activity and isoform composition were detected when ,-naphthyl propionate was used as a substrate. Moreover, esterase activity and diverse isoforms were present in gut mitochondrial, microsomal, and cytosolic sub-cellular protein fractions, as well as in the hindgut lumen. These findings reveal an agreement between gut esterase gene expression and activity distributions, and support the idea that R. flavipes gut esterase activity is host (not symbiont)-derived. In addition, these findings support the hypotheses that termite gut esterases may play important roles in lignocellulose digestion and caste differentiation. This study provides important baseline data that will assist ongoing functional-genomic efforts to identify novel genes with roles in semiochemical, hormone, and lignocellulose processing in the termite gut. © 2009 Wiley Periodicals, Inc. [source] Esterase-based resistance in the tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) in the eastern United StatesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009Lakshmipathi Srigiriraju Abstract Organophosphates and carbamates represent alternative insecticides in managing the tobacco-adapted form of the green peach aphid (TGPA), Myzus persicae (Sulzer), a major pest of tobacco in the United States and around the world. General esterases that detoxify these insecticides were assessed in green, red, and orange morphs of field-collected M. persicae. A total of 136 aphid colonies were collected from 2004 though 2007 and screened for total esterase activity. The green morphs had lower esterase levels, with a mean of 77±6.6,nmol/min/mg protein, as compared to red (84±2.9,nmol/min/mg protein) and orange morphs (172±16.5,nmol/min/mg protein). Overall esterase activities, and those for the red and green morphs, were positively correlated with LC50 values for acephate (organophosphate) and methomyl (carbamate) assessed in leaf-dip bioassays. Esterase genes responsible for higher esterase activities were diagnosed by gene amplification studies. Twenty-three of 24 colonies tested had either the E4 or FE4 gene amplified, both known to confer esterase-based resistance. Fifteen out of the 24 colonies tested had amplified E4 gene and four colonies had FE4 gene amplification. All orange morphs and one green morph had both E4 and FE4 genes amplified. This unique phenotype, where two esterase genes were amplified had an 865-bp band characteristic of the FE4 gene and an additional 381-bp band characteristic of a deleted upstream region of the E4 gene. Changes that occurred in esterase-based resistance in the TGPA over the past two decades and their implications on insecticide resistance management are discussed. © 2009 Wiley Periodicals, Inc. [source] Insecticide resistance in the aphid Myzus persicae (Sulzer): chromosome location and epigenetic effects on esterase gene expression in clonal lineagesBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2003LINDA M. FIELD Insecticide treatment of the aphid Myzus persicae (Sulzer) has led to the evolution of several insecticide resistance mechanisms, including the detoxification of insecticides by elevated esterases. This results from amplification of one of two closely related esterase genes (E4 or FE4) with up to 80 copies in the most resistant aphids. The amplified E4 genes are at a single site linked to a chromosomal translocation and resistance can be unstable. Individuals within a clone lose their elevated esterase and resistant phenotype, a good example of ,clonal variation'. This loss of esterase is accompanied by a loss of the corresponding mRNA but the amplified genes are retained with no detectable sequence differences. However, the expressed E4 genes contain 5-methylcytosine, which is lost at the same time as the genes are turned off. This is in direct contrast with vertebrate genes where DNA methylation causes gene silencing, but it does suggest that the resistant phenotype in M. persicae is under epigenetic control. One hypothesis is that 5-methylcytosine in E4 genes facilitates expression by preventing the production of incorrectly initiated transcripts. It is interesting that we have never detected silencing of amplified FE4 genes, possibly because they are at multiple loci and therefore less likely to be subject to synchronous control. © 2003 The Linnean Society of London. Biological Journal of the Linnean Society, 2003, 79, 107,113. [source] | ||||||||||