Understanding Gas Phase Modifier Interactions in Rapid Analysis by Differential Mobility-Tandem Mass Spectrometry

A systematic study involving the use and optimization of gas phase modifiers in quantitative differential mobility- mass spectrometry (DMS-MS) analysis is presented using mucleoside-adduct biomarkers of DNA damage as an important reference point for analysis in complex matrices. Commonly used polar protic and polar aprotic modifiers have been screened for use against two deoxyguanosine adducts of DNA: N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-4-ABP) and N-(deoxyguanosin-8-y1)-2-amino-l-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP). Particular attention was paid to compensation voltage (CoV) shifts, peak shapes and product ion signal intensities while optimizing the DMS-MS conditions. The optimized parameters were then applied to rapid quantitation of the DNA adducts in calf thymus DNA. After a protein precipitation step, adduct levels corresponding to less than one modification in 10(6) normal DNA bases were detected using the DMS-MS platform. Based on DMS fundamentals and ab-initio thermochemical results we interpret the complexity of DMS modifier responses in terms of thermal activation and the development of solvent shells. At very high bulk gas temperature, modifier dipole moment may be the most important factor in cluster formation and cluster geometry in mobility differences, but at lower temperatures multi-neutral clusters are important and less predictable. This work provides a useful protocol for targeted DNA adduct quantitation and a basis for future work on DMS modifier effects

Biological, environmental and socioeconomic threats to citrus lime production

Limes as a fruit crop are of great economic importance, key to Asian and South American cuisines and cultivated in nearlyall tropical and subtropical regions of the world. Demand for limes is increasing, driven by World Health Organizationrecommendations. Pests and pathogens have significantly reduced global productivity, while changes in agronomictechniques aim to alleviate this stress. We present here a holistic examination of the major biotic (pests and pathogens) andabiotic (environment and socioeconomic) factors that presently limit global production of lime. The major producers oflimes are India, China and Mexico, while loss of lime production in the United States from 2006 has led many countries inthe Western Hemisphere (Mexico, Costa Rica and Brazil) to export primarily to the USA. The most widespread inver-tebrate pests of lime areToxoptera citricidaandScirtothrips citri. Another insect,Diaphorina citri, vectors both Huan-glongbing (HLB) and Witches Broom of Lime, which are particularly destructive diseases. Developing agronomictechniques focus on production of resistant and pathogen-free planting materials and control of insect vectors. HLB infectscitrus in nearly all growing regions, and has been particularly devastating in Asian citrus. Meanwhile,Citrus tristeza virushas infected over 100 million citrus trees, mainly in the Americas and Mediterranean. Currently, Witches Broom Disease ofLime is localised to the Middle East, but recently it has been detected in South America. The range of its vectors (D. citriandHishimonus phycitis) further raises concerns about the potential spread of this disease. Abiotic threats to limeproduction are also a significant concern; key areas of lime production such as Mexico, India and the Middle East sufferfrom increasing water stress and high soil salinity, which combined with invasive pests and pathogens, may eliminate limeproduction in these areas. To ensure future security in lime production, policy makers, researchers and growers will need toexamine the potential of more resistant lime cultivars and establish novel areas of cultivation

A review of the major biological approaches to control the worldwide pest Tetranychus urticae (Acari: Tetranychidae) with special reference to natural pesticides

The two-spotted spider mite, Tetranychus urticae Koch, is a phytophagous pest that can cause significant yield losses in many agricultural crops, including fruits, cotton, vegetables, and ornamentals. To date, 3877 host species have been reported around the world in both outdoor crops and greenhouses. In this paper, we present the common methods to control this pest including chemical and biological practices. While synthetic acaricides have been widely used to manage T. urticae, in recent years, interest in pesticides derived from plants has increased considerably as a result of environmental concerns and pest population resistance to conventional pesticides. Some botanical pesticides can be easily produced,are relatively efficient against pests, and with few exceptions, their mammalian toxicity and persistence in the environment is low. Thus, the use of plant extracts appears to be a promising alternative strategy for pest management. The present paper reviews studies on the biocidal activities of plant extracts, including essential oils, against T. urticae, a plant-feeding mite found worldwide and a serious agricultural and home garden pest