-
[show abstract]
[hide abstract]
ABSTRACT: Aphis gossypii (Glover) has been found to possess multiple mutations in the acetylcholinesterase (AChE) gene (Ace) that might involve target site insensitivity. In vitro functional expression of AChEs reveals that the resistant Ace1 (Ace1R) and Ace2 (Ace2R) were significantly less inhibited by eserine, omethoate, and malaoxon than the susceptible Ace1 (Ace1S) and Ace2 (Ace2S). Furthermore, in both the mutant and susceptible AChEs, Ace2 was significantly less sensitive to eserine, omethoate, and malaoxon than Ace1. These results suggested that both the mutant Ace1 and Ace2 were responsible for omethoate resistance, while the mutant Ace2 played a major role in insecticide resistance. The DNA copy number and transcription level of Ace2 were 1.52- and 1.88-fold higher in the ORR strain than in the OSS strain. Furthermore, the DNA copy number and transcription level of Ace2 were significantly higher than that of Ace1 in either OSS or ORR strains, demonstrating the involvement of Ace2 gene duplication in resistance. Thus, the authors conclude that omethoate resistance in cotton aphids appears to have evolved through a combination of multiple mutations and extensive Ace2R gene duplication. © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012.
Environmental Toxicology 04/2012; · 2.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The degree of insecticide resistance, acetylcholinesterase (AChE) activity kinetics, AChE gene expression and the cDNA sequence of AChE gene were investigated in resistant and relatively susceptible strains of the cotton aphids, Aphis gossypii (Glover). The resistant strain (ORR) exhibited 53.28-fold resistance to omethoate compared to the relatively susceptible strain (OSS) in cotton aphids. AChE activity, V(max) and K(m) were significantly lower in the ORR strain than in the OSS strain (0.13-, 0.04- and 0.31-fold, respectively). Based on analysis of IC(50) indices, enzyme inhibition experiments showed that AChE from the ORR strain was 7.99-, 4.12-, 4.27-, 8.71- and 4.57-fold insensitive to inhibition by eserine, omethoate, paraoxon, paraoxon-methyl and malaoxon than the OSS strain. Sequence analysis indicated that there were no amino acid substitutions in AChEI (Ace1) and AChEII (Ace2) between the OSS and ORR strain. However, when compared with the 81-171B strain (GenBank No. AF502081), we detected two site mutations (S146N and L532P) in Ace1 with high frequency in both the ORR and OSS strains. One conserved mutation (S431F) in Ace2 was also found in both strains when compared with the 171B strain (GenBank No. AJ748114). Measurements of the levels of gene expression for Ace1 and Ace2 in ORR and OSS, as determined by real-time quantitative PCRs, revealed that the relative transcription levels of Ace1 and Ace2 were 0.26- and 1.07-fold, respectively, in the ORR strain as compared to the OSS strain. These results indicate that the altered AChE sensitivity brought about by a decreased transcriptional level of Ace1 mRNA and combined with the site mutants in both Ace1 and Ace2 might be related to omethoate resistance in cotton aphids.
Chemico-biological interactions 12/2010; 188(3):553-7. · 2.46 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Arabidopsis ethylene responsive element binding factors (AtERFs) form a transcription factor super family. While the functions of most AtERFs are unknown, a number of AtERFs appear to be involved in regulation of stress-related genes through their DNA binding domains (DBD), namely ERF domains, which recognize a consensus motif GCC-box at the regulatory region. In this study, molecular dynamics simulations were performed on the four ERF domain-GCC-box complexes, AtERF1, AtERF4, AtEBP and CFBF1, to determine disparity in specific binding to the GCC-box by the AtERFs. Our results suggested that three amino acid residues Arg29, Glu39 and Arg41, played a vital role in direct readout of DNA. The position of the consensus sequence GCCGCC has an intrinsic disparity on binding with ERF domains. The third C, fourth G and the last C in the GCC motif was compulsory for recognition by ERF domains. Our results provide structural evidence for a sequence-dependent recognition mechanism for AtERFs.
Journal of Molecular Recognition 06/2009; 22(6):474-9. · 3.31 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Extraction of plant proteins using typical extraction buffers leaves insoluble debris that cannot be investigated by conventional 2-DE technologies. In this paper, we present a scalable, off-line procedure for extraction of Arabidopsis thaliana homogenates that can be used in combination with both in-gel digestion and mass spectrometry. Based on sequential NaCl gradients and strong detergent fractionation, this new strategy allowed detection of 11 novel proteins from Arabidopsis thaliana that were altered in response to chilling stress.
Biotechnology Letters 05/2009; 31(8):1289-95. · 1.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Poor detection of low-abundant proteins is a common problem in two-dimensional electrophoresis (2-DE) for separation of proteins in a proteome analysis. This is attributed partially, at least, to the existence of high-abundant proteins, e.g. ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in plants. They engage a large proportion of the whole-cell proteins and thus prevent low-abundant proteins from being up-taken by immobilized pH gradient (IPG) strip, consequently making the latter poorly detectable by 2-DE. In this work, we report a straightforward protocol for preparation of whole-cell proteins through differential polyethylene glycol (PEG) precipitation aiming at elimination of Rubisco from plant protein samples. In comparison with 2-DE analysis of protein samples prepared using a conventional TCA/acetone method, a relatively high reproducibility of proteins was achieved using a PEG fractionation protocol in terms of protein yield and protein species. As expected, the large subunit of Rubisco was precipitated predominantly in the 16% PEG fraction. This allowed proteins of the Rubisco-containing fraction to be analyzed separately from those of other PEG fractions. After taking into account the overlapping protein spots among 2-DE gels of all fractions through image and statistical analyses, we detected with this protocol a total 5077 protein spots, among which ca. 80% are proteins undetectable with the TCA/acetone method, while the rest of proteins exhibited a significant increase in their abundance. This protocol was developed using Arabidopsis as a source of protein and thus may also be applicable to protein preparations of other plants.
Phytochemistry 12/2006; 67(21):2341-8. · 3.35 Impact Factor
