Prospects for the management of arthropod resistance to pesticides

Extensive use has been made of mathematical modelling to examine many of the factors which are involved in the development of pesticide resistance in arthropods. These models have demonstrated that the emergence of resistance can be delayed if more attention is given to planned use of pesticides at the time of their introduction. However the practical application of such delaying strategies at the national or even regional level may be difficult. It is unfortunate that the suggestions made have not been subjected to more extensive testing in the field situation.It is suggested that the contribution of molecular biology to the management of pests and pesticide resistance in arthropod livestock pests will be significant and will be seen in a variety of ways. Very definitely, a greater understanding of the basic molecular processes involved in the development of resistance will be seen. Such work, always in conjunction with the other biological disciplines, will provide new techniques for the control, prediction, detection and prevention of pesticide resistance. A few entirely conjectural examples of the practical application of molecular biology to pesticide resistance and its management have been presented.     

香蕉基因组测序及胁迫相关功能基因研究进展

香蕉是重要的热带水果之一,是世界第四大粮食作物。香蕉抗性相关的功能基因组学研究一直是香蕉研究的热点和核心。综述了近年来香蕉基因组测序、胁迫相关功能基因分离和鉴定等方面的最新研究进展,将有助于从源头上对香蕉进行创新性的研究,为香蕉遗传改良和新品种培育提供一定的理论依据。     

Evolution of plant resistance at the molecular level: ecological context of species interactions

Molecular data regarding the diversity of plant loci involved in resistance to herbivores or pathogens are becoming increasingly available. These genes demonstrate variable patterns of diversity, suggesting that they differ in their evolutionary history. In parallel, the study of natural variation for resistance, generally conducted at the phenotypic level, has shown that resistance does not evolve solely under selection pressures exerted by enemies. Metapopulation dynamics and other ecological characteristics of interacting species also appear to have a large impact on resistance evolution. Until now, studies of resistance at the molecular level have been conducted separately from ecological studies in extant populations. Future progress requires an evolutionary approach integrating both molecular and ecological aspects of resistance evolution. Such an approach will contribute greatly to our understanding of the evolution of molecular diversity at loci involved in biotic stress.     

Insulin resistance at the crossroads of metabolic syndrome: Systemic analysis using microarrays

Recently, it has been suggested that insulin resistance is a better predictor of metabolic syndrome than obesity. Numerous studies have been conducted to identify insulin resistance susceptibility genes in various model systems. This review focuses on recent findings in microarray analyses, which have indicated that (i) in the liver, genes involved in lipid synthesis and gluconeogenesis are increased in an animal model of insulin resistance that leads into liver steatosis and hyperglycemia; (ii) in adipose tissues, genes involved in fatty acid synthesis and adipogenesis are down-regulated both in insulin-resistant humans and in animals; and (iii) in muscle, overall gene expression, including genes involved in fatty acid oxidation and biosynthesis, is either decreased or unresponsive compared to that of insulin-sensitive control human subjects or animals. Considering the multifaceted effects of insulin resistance in various tissues, aiming at multi-targets rather than a single target will be a more promising strategy for the prevention or treatment of insulin resistance.     

Outer membrane proteins: key players for bacterial adaptation in host niches

Outer membrane proteins (OMPs) of Gram-negative bacteria have diverse functions and are directly involved in the interaction with various environments encountered by pathogenic organisms. Thus, OMPs represent important virulence factors and play essential roles in bacterial adaptation to host niches, which are usually hostile to invading pathogens. Understanding the structure and functions of bacterial OMPs will facilitate the design of antimicrobial drugs and vaccines. In this paper, we will present a brief review on OMPs that contribute to bacterial adaptive responses including iron uptake, antimicrobial peptide resistance, serum resistance, and drug/bile resistance.     

昆虫对Ｂt毒素的抗性机理研究进展

文中综述了昆虫对苏云杆菌（Ｂt)毒素产生抗性的生化遗传机理及抗性的遗传及交叉抗性情况。昆虫对Ｂt毒素的抗性可能在６个环节发生,其中与毒素特异结合的受体上结合位点的改变及毒素水解过程中的变化是抗性产的两个主要环节。从现有的研究结果来看,实验室及田间抗性昆虫品系对Ｂt毒素产生的抗性主要与昆虫中肠上皮细胞膜上Ｂt毒素特异结合受体的变化有关,深入研究是昆虫对Ｂt毒素的抗性机理,将有助于建立抗性的早期监测技术、抗性治理措施,实施无公害Ｂt农药及转Ｂt基因作物的持续利用。     

Molecular tools for the rapid detection of drug resistance in animal trypanosomes

There are currently 17 African countries in which animal trypanocidal drug resistance has been reported. Large-scale surveys were carried out in only ten of them. The lack of baseline information is mainly due to the fact that the methods currently available for the detection of drug resistance are laborious, expensive and time consuming. In this review the mechanisms involved in resistance to isometamidium and diminazene will be discussed, together with some new molecular detection tools that have been developed recently enabling faster diagnosis of drug resistance than conventional laboratory or field tests.     

Mapping QTLs associated with drought resistance in sorghum (Sorghum bicolor L. Moench)

Drought is a major abiotic stress factor limiting crop production. Identification of genetic factors involved in plant responses to drought stress will provide a solid foundation to improve drought resistance. Sorghum is well adapted to hot dry environments and regarded as a model for studying drought resistance among the grasses. Significant progress in genome mapping of this crop has also been made. In sorghum, rapid premature leaf death generally occurs when water is limited during the grain filling period. Premature leaf senescence, in turn, leads to charcoal rot, stalk lodging, and significant yield loss. More than 80% of commercial sorghum hybrids in the United States are grown under non-irrigated conditions and although most of them have pre-flowering drought resistance, many do not have any significant post-flowering drought resistance. Stay-green is one form of drought resistance mechanism, which gives sorghum resistance to premature senescence under soil moisture stress during the post-flowering period. Quantitative trait locus (QTL) studies with recombinant inbred lines (RILs) and near-isogenic lines (NILs) identified several genomic regions associated with resistance to pre-flowering and post-flowering drought stress. We have identified four genomic regions associated with the stay-green trait using a RIL population developed from B35 × Tx7000. These four major stay-green QTLs were consistently identified in all field trials and accounted for 53.5% of the phenotypic variance. We review the progress in mapping stay-green QTLs as a component of drought resistance in sorghum. The molecular genetic dissection of the QTLs affecting stay-green will provide further opportunities to elucidate the underlying physiological mechanisms involved in drought resistance in sorghum and other grasses.     

Purinoceptors in the kidney

The multiple roles of extracellular ATP and its metabolite adenosine include broad areas, such as regulating vascular tone and inducing inflammation. This review will discuss purinoceptor-induced effects on renal vascular resistance, highlighting the key experiments providing a significant contribution to our current understanding of autoregulatory mechanisms. Emphasis will be placed on the purinoceptor subtypes involved in autoregulatory control by ATP and adenosine. Additionally, the role of purinoceptors in hypertension-associated impairment of autoregulatory efficiency will be discussed.     

植物WRKY转录因子家族基因抗病相关功能的研究进展

植物基因组中,数目众多的转录因子参与植物的生长发育、物质代谢、响应生物和/或非生物胁迫等多种生物进程.WRKY基因家族是植物重要的转录因子家族,在抗病信号转导途径中起重要调控作用,因而成为分子植物病理研究领域中的热点.本文综述了WRKY转录因子基因在植物抗病反应中的作用和调节机制的最新研究进展,以期为深入研究WRKY基因家族在植物抗病反应中的作用,阐明植物抗病信号转导途径提供帮助.     

Thioridazine affects transcription of genes involved in cell wall biosynthesis in methicillin-resistant Staphylococcus aureus

The antipsychotic drug thioridazine is a candidate drug for an alternative treatment of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in combination with the β-lactam antibiotic oxacillin. The drug has been shown to have the capability to resensitize MRSA to oxacillin. We have previously shown that the expression of some resistance genes is abolished after treatment with thioridazine and oxacillin. To further understand the mechanism underlying the reversal of resistance, we tested the expression of genes involved in antibiotic resistance and cell wall biosynthesis in response to thioridazine in combination with oxacillin. We observed that the oxacillin-induced expression of genes belonging to the VraSR regulon is reduced by the addition of thioridazine. The exclusion of such key factors involved in cell wall biosynthesis will most likely lead to a weakened cell wall and affect the ability of the bacteria to sustain oxacillin treatment. Furthermore, we found that thioridazine itself reduces the expression level of selected virulence genes and that selected toxin genes are not induced by thioridazine. In the present study, we find indications that the mechanism underlying reversal of resistance by thioridazine relies on decreased expression of specific genes involved in cell wall biosynthesis.     

Sequestosome 1/p62: across diseases

Sequestosome 1/p62 is a signal modulator or adaptor protein involved in receptor-mediated signal transduction. Sequestosome 1/p62 is gaining attention as it is involved in several diseases including Parkinson disease, Alzheimer disease, liver and breast cancer, Paget's disease of bone, obesity and insulin resistance. In this review, we will focus on the most recent advances on the physiological function of p62 relevant to human diseases.     

Proteomic approaches for studying chemoresistance in cancer

The role of various proteins involved in drug resistance in tumor cells is discussed in this review. Two types of studies are covered: those performed in the preproteomics era and those carried out with modern proteomic tools, namely 2D (electrophoretic) maps and 2D chromatography. In the preproteomic studies, one protein had generally been held responsible for a given chemoresistance. However, analysis via proteomic tools may reveal entire sets of proteins that are up- or downregulated (or switched on/off) in chemoresistant tumor cell lines compared with parental tumor lines. Therefore, it appears more realistic to expect that exposure of cells to drugs results in the activation of different mechanisms of resistance. Such investigations have led to the broadly shared opinion that exposure of cells to drugs results in the activation of different mechanisms of resistance, and that a specific drug-resistant phenotype consists of several molecular mechanisms that are simultaneously active. The proteomic papers reviewed clearly support the hypothesis that many metabolic pathways are affected during the resistance process. Although the modulation of expression levels of such proteins is not clear proof of their role in drug resistance per se, at least some of the themes are very likely to be involved in the resistance phenotype, and thus may be potential targets for new drugs. It is hoped that this review will bring new insight in this field and will stimulate novel and deeper searches with proteomic tools (including prefractionation of subcellular organelles, such as nuclei, to bring to the fore low-abundance proteins that might be responsible for the onset of drug resistance).     

Proteomic approaches for studying chemoresistance in cancer

The role of various proteins involved in drug resistance in tumor cells is discussed in this review. Two types of studies are covered: those performed in the preproteomics era and those carried out with modern proteomic tools, namely 2D (electrophoretic) maps and 2D chromatography. In the preproteomic studies, one protein had generally been held responsible for a given chemoresistance. However, analysis via proteomic tools may reveal entire sets of proteins that are up- or downregulated (or switched on/off) in chemoresistant tumor cell lines compared with parental tumor lines. Therefore, it appears more realistic to expect that exposure of cells to drugs results in the activation of different mechanisms of resistance. Such investigations have led to the broadly shared opinion that exposure of cells to drugs results in the activation of different mechanisms of resistance, and that a specific drug-resistant phenotype consists of several molecular mechanisms that are simultaneously active. The proteomic papers reviewed clearly support the hypothesis that many metabolic pathways are affected during the resistance process. Although the modulation of expression levels of such proteins is not clear proof of their role in drug resistance per se, at least some of the themes are very likely to be involved in the resistance phenotype, and thus may be potential targets for new drugs. It is hoped that this review will bring new insight in this field and will stimulate novel and deeper searches with proteomic tools (including prefractionation of subcellular organelles, such as nuclei, to bring to the fore low-abundance proteins that might be responsible for the onset of drug resistance).     

Identification of quantitative trait loci controlling partial clubroot resistance in new mapping populations of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

To date, mechanisms of partial quantitative resistance, under polygenic control, remain poorly understood, studies of the molecular basis of disease resistance have mainly focused on qualitative variation under oligogenic control. However, oligogenic conferred resistance is rapidly overcome by the pathogen and knowledge of the relationship between qualitative and quantitative resistance is necessary to develop durably resistant cultivars. In this study, we exploited the Arabidopsis thaliana-Plasmodiophora brassicae pathosystem to decipher the genetic architecture determining partial resistance. This soil-borne pathogen causes clubroot, one of the economically most important diseases of Brassica crops in the world. A quantitative trait locus (QTL) approach was carried out using two segregating populations (F(2) and recombinant inbred lines) from crosses between the partially resistant accession Burren and the susceptible accession Columbia. Four additive QTLs (one moderate and three minor) controlling partial resistance to clubroot were identified, all the resistance alleles being derived from the partially resistant parent. In addition, four epistatic regions, which have no additive effect on resistance, were also found to be involved in partial resistance. An examination of candidate genes suggested that a potentially diverse array of mechanisms is related to the different QTLs. By fine-mapping and cloning these regions, the mechanisms involved in partial resistance will be identified.     

Alterations of protein complexes and pathways in genetic information flow and response to stimulus contribute to Escherichia coli resistance to balofloxacin

Protein-protein interactions are important biological processes and essential for a global understanding of cell functions. To date, little is known about the protein interactions and roles of the protein interacting networks and protein complexes in bacterial resistance to antibiotics. In the present study, we investigated protein complexes in Escherichia coli exposed to an antibiotic balofloxacin (BLFX). One homomeric and eight heteromeric protein complexes involved in BLFX resistance were detected. Potential roles of these complexes that are played in BLFX resistance were characterized and categorized into four functional areas: information streams, monosaccharide metabolism, response to stimulus and amino acid metabolic processes. Protein complexes involved in information streams and response to stimulus played more significant roles in the resistance. These results are consistent with previously published mechanisms on the acquired quinolone-resistance through the GyrA-GyrB complex, and two novel antibiotic-resistant pathways were identified: upregulation of genetic information flow and alteration of the response to a stimulus. The balance of the two pathways will be a viable means of reducing BLFX-resistance.     

MicroRNAs: key players of taxane resistance and their therapeutic potential in human cancers

The successful long‐term use of taxane for cancer therapy is often prevented by the development of drug resistance in clinic. Thus, exploring the mechanisms involved is a first step towards rational strategies to overcome taxane resistance. Taxane resistance‐related microRNA (miRNAs) are under investigation and miRNAs could induce the taxane resistance of tumour cells by regulating cell cycle distribution, survival and/or apoptosis pathways, drug transports, epithelial–mesenchymal transition and cancer stem cell. This article summarizes current research involving miRNAs as regulators of key target genes for tanxanxe chemoresistance and discusses the complex regulatory networks of miRNAs. Also, the authors will envisage future developments towards the potential use of targeting miRNAs as a novel strategy for improving response of tumour patients to taxane. miRNAs play critical roles in taxane chemoresistance and the miRNA‐based therapies will be helpful for overcoming drug resistance and developing more effective personalized anti‐cancer treatment strategies. Further research studies should be performed to promote therapeutic–clinical use of taxane resistance‐related miRNAs in cancer patients, especially in those patients with taxane‐resistant cancers.