Determination of five macrolide antibiotic residues in raw milk using liquid chromatography-electrospray ionization tandem mass spectrometry     

Wang J  Leung D  Lenz SP 《Journal of agricultural and food chemistry》2006,54(8):2873-2880

A confirmatory method using liquid chromatography-electrospray ionization tandem mass spectrometry for determination of five macrolide antibiotics including spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin in raw milk is presented. Macrolides were extracted from raw milk by acetonitrile, and sample extracts were further cleaned up using solid-phase extraction cartridges. Data acquisition was achieved using multiple reaction monitoring, that is, two transitions, to provide a high degree of sensitivity and specificity. Matrix-matched standard calibration curves with the use of roxithromycin as an internal standard were utilized to achieve the best accuracy of the method. Both a conventional validation procedure and a designed experiment were applied to study the accuracy and precision of the method. The measurement uncertainty arising from accuracy and precision was estimated. The method accuracy, expressed as a percentage of overall recovery, was approximately 100%, and its intermediate precision was <10%. LC-ESI/MS/MS method detection limits (S/N > or = 3:1) of five macrolides were <0.3 microg/kg.  相似文献   

Development and evaluation of a high-throughput,low-cost genotyping platform based on oligonucleotide microarrays in rice     

Jeremy D Edwards  Jaroslav Janda  Megan T Sweeney  Ambika B Gaikwad  Bin Liu  Hei Leung  David W Galbraith 《Plant methods》2008,4(1):13

Background  

We report the development of a microarray platform for rapid and cost-effective genetic mapping, and its evaluation using rice as a model. In contrast to methods employing whole-genome tiling microarrays for genotyping, our method is based on low-cost spotted microarray production, focusing only on known polymorphic features.  相似文献   

应用分子标记技术鉴证稻瘟病菌宗谱与寄主遗传背景的亲缘关系   总被引：12，自引：3，他引：9  

伍尚忠  朱小源  杨祁云  罗林  刘斌  张少红  H. Leung  T.W.Mew 《中国农业科学》1999,32(6):56-62

用散布性重复序列MGR586探针与EcoRI组合,分析广东省稻区的112个稻瘟病菌株（M.grisea）的限制性片段长度多态性（RFLPs）,根据带型相似性大于80%为度划分为15个遗传宗谱（genetic lineage）。这些在分子水平上划分的宗谱与寄主品种的遗传背景关系密切。由于广东省（包括华南稻区）大多数育成的常规稻品种和杂交稻组合在遗传背景上与GDL1及GDL2两个优势病菌宗谱寄主具有相似的共进化同缘宗亲关系,致使品种的抗性水平不高,抗性周期短暂。从而提出了选择异源供体,开展多元化育种的方向及途径。  相似文献   

Macroalgal meadow habitats support fish and fisheries in diverse tropical seascapes     

Christopher J. Fulton  Charlotte Berkstrm  Shaun K. Wilson  Rene A. Abesamis  Michael Bradley  Carolina kerlund  Luke T. Barrett  Abner A. Bucol  Dinorah H. Chacin  Karen M. Chong‐Seng  Darren J. Coker  Martial Depczynski  Linda Eggertsen  Maria Eggertsen  David Ellis  Richard D. Evans  Nicholas A. J. Graham  Andrew S. Hoey  Thomas H. Holmes  Michel Kulbicki  Priscilla T. Y. Leung  Paul K. S. Lam  Joshua van Lier  Paloma A. Matis  Mae M. Noble  Alejandro Prez‐Matus  Camilla Piggott  Ben T. Radford  Stina Tano  Paul Tinkler 《Fish and Fisheries》2020,21(4):700-717

Canopy‐forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life‐history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta‐analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal‐associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life‐history stage. Major overlap (40%–43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal‐associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal‐associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal‐associated fish and fisheries.  相似文献   

Rapid testing methods for food contaminants and toxicants     

Jiachi Chiou  Arthur Ho Hon Leung  Hang Wai Lee  Wing-tak Wong 《农业科学学报》2015,14(11):2243-2264

Food safety is one of the major concerns in every country regardless of the economic and social development. The frequent occurrence of food scandals in the world has led the Chinese government to implement several strategies to fortify the food supply system to a high food safety standard. This relies heavily on laboratory testing services but conventional methods for detection of food contaminants and toxicants are limited by sophisticated sample preparation procedures,long analysis time,large instruments and professional personnel to meet the increasing demands. In this review,we have incorporated most of the current and potential rapid detection methods for many notorious food contaminants and toxicants including microbial agents,toxic ions,pesticides,veterinary drugs and preservatives,as well as detection of genetically modified food genes and adulterated edible oil. Development of rapid,accurate,easy-to-use and affordable testing methods could urge food handlers and the public to actively screen for food contaminants and toxicants instead of passively relying on monitoring by the government examination facility. This review also provides several recommendations including how to encourage the public to engage in the food safety management system and provide optimal education and financial assistance that may improve the current Chinese food safety control system.  相似文献   

Application of Chinese herbal medicine onto cotton fabric by dyeing methods     

Wenyi Wang  Elaine Wat  Patrick C. L. Hui  Frency S. F. Ng  C. W. Kan  Eric C. W. Wong  Ben Chan  Clara B. S. Lau  Ping-Chung Leung 《Fibers and Polymers》2015,16(11):2401-2408

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Economics of milkfish (Chanos chanos) production in Hawaii*     

Lotus E. Kam  Francisco J. Martínez‐Cordero  Pingsun Leung  Anthony C. Ostrowski 《Aquaculture Economics & Management (Blackwell Science)》2013,17(1-2):95-123

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.  相似文献   

Rice Germin-Like Proteins: Allelic Diversity and Relationships to Early Stress Responses   总被引：1，自引：0，他引：1  

Rebecca M. Davidson  Patricia M. Manosalva  Jacob Snelling  Myron Bruce  Hei Leung  Jan E. Leach 《Rice》2010,3(1):43-55

Germin-like protein (GLP) markers were associated with quantitative trait loci (QTL) for resistance to the rice blast pathogen, Magnaporthe oryzae in multiple rice (Oryza sativa) mapping populations. Twelve paralogous OsGLP gene family members are located within the physical QTL region on chromosome 8, and gene silencing studies suggest that they contribute collectively to the resistance phenotype. We compared sequence and expression profiles of OsGLP alleles in two resistant and two susceptible parental rice lines to find functional polymorphisms that correlated with the resistant phenotype. Based on coding and promoter sequences, the genes belong to two germin subfamily groups (GER3 and GER4). OsGLP members from both subfamilies were constitutively expressed and developmentally regulated in all cultivars. Transient induction above constitutive levels was observed for some OsGLPs, especially GER4 subfamily members, at early time points after M. oryzae infection and mechanical wounding. Varying 5′ regulatory regions and differential expression of some family members between resistant and susceptible cultivars corresponded with differential hydrogen peroxide (H₂O₂) accumulation after the same stimuli. OsGLP of both GER subfamilies localized to the plant cell wall. The protein location and early gene induction suggest that OsGLPs protect rice leaves at early stages of infection before fungal penetration and subsequent ingress. Our data suggest that regulation of OsGLP genes defines resistant versus susceptible phenotypes.  相似文献   

The effect of simulated rat damage on irrigated rice yield and compensation     

Nguyen Thi My Phung  Peter R. Brown  K.-P. Leung Luke  Luu Minh Tuan 《Crop Protection》2010

A field experiment was conducted to investigate the impact of simulated rat damage on grain yield in irrigated lowland rice in An Giang province, in the Mekong Delta of Vietnam. Rat damage was simulated by making a 45° cut at the base of the rice tillers about 3–5 cm above the soil surface. 0% (control), 5%, 10%, 25% and 50% of the tillers were removed at the tillering (25 days after sowing, DAS), panicle initiation (43 DAS), flowering (72 DAS) and ripening (87 DAS) stages. The total number of mature tillers, immature tillers and percent filled grains, the weight of 1000 grains and grain yields were recorded. The rice crop completely compensated by increased tillering and yield for tillers damaged up to 50% at the tillering stage. However, the damage and yield loss were highly variable. The ability of the rice crop to compensate at later stages progressively reduced. The implications for managing rat damage to rice crops are (1) rodent control activities should be applied before 10% of tillers are damaged at the tillering stage, and (2) a well balanced nitrogen supply during the tillering stage could potentially assist the rice plants to better compensate for rat damage.  相似文献   

Schisandrin B co-treatment ameliorates the impairment on mitochondrial antioxidant status in various tissues of long-term ethanol treated rats     

Philip Y. Lam  Po Yee Chiu  Hoi Yan Leung  Na Chen  Pou Kuan Leong  Kam Ming Ko   《Fitoterapia》2010,81(8):1239-1245

The effect of schisandrin B (Sch B) on long-term ethanol-induced oxidative stress in various rat tissues was investigated. Long-term ethanol treatment increased reactive oxygen metabolites (ROM) level in plasma. The ethanol-induced oxidative stress was assessed by mitochondrial glutathione and α-tocopherol levels, antioxidant enzyme activities, malondialdehyde (mtMDA) production and heat shock protein (Hsp) 25/70 levels. Liver was most susceptible to oxidative stress with a significant increase in mtMDA production. Long-term Sch B treatment enhanced mitochondrial antioxidant status in a tissue non-specific manner. Sch B co-treatment ameliorated the alterations in plasma ROM levels, mtMDA production and Hsp 25/70 expression in rat tissues.  相似文献