我国水果防腐保鲜剂的使用及其检测方法

水果是我国最主要的植物源鲜活农产品之一,防腐保鲜和防腐保鲜剂对我国水果的生产、贮藏、运输与销售作用重大,是我国实现水果季节性生产和长期性供应的关键。本文从水果贮运中使用的主要防腐保鲜剂、我国允许使用的水果防腐保鲜剂、我国水果防腐保鲜剂最大残留限量以及水果防腐保鲜剂残留测定方法等4个方面,对我国水果防腐保鲜剂的使用与检测方法进行了综述,并指出水果防腐保鲜剂的合理使用和有效监管是保护消费者人体健康的关键。     

A quantitative real‐time PCR assay for detection of Colletotrichum lindemuthianum in navy bean seeds

Bean anthracnose is a seedborne disease of common bean (Phaseolus vulgaris) caused by the fungal pathogen Colletotrichum lindemuthianum. Using seed that did not test positive for the pathogen has been proven to be an effective strategy for bean anthracnose control. To quantify the extent of anthracnose seed infection, a real‐time PCR‐based diagnostic assay was developed for detecting C. lindemuthianum in seeds of the commercial bean class navy bean. The ribosomal DNA (rDNA) region consisting of part of the18S rDNA, 5^.8S rDNA, internal transcribed spacers (ITS) 1, 2 and part of the 28S rDNA of seven races of C. lindemuthianum, 21 isolates of Colletotrichum species and nine other bean pathogens were sequenced with the universal primer set ITS5/ITS4. Based on the aligned sequence matrix, one primer set and a probe were designed for a SYBR Green dye assay and a TaqMan MGB (minor groove binder) assay. The primer set was demonstrated to be specific for C. lindemuthianum and showed a high sensitivity for the target pathogen. The detection limit of both assays was 5 fg of C. lindemuthianum genomic DNA. To explore the correlation between the lesion area and the DNA amount of C. lindemuthianum in bean seed, seeds of the navy bean cultivar Navigator with lesions of different sizes, as well as symptomless seeds, were used in both real‐time PCR assays.     

Histopathology of grossly normal mesenteric lymph nodes of New Zealand farmed red deer (Cervus elaphus) including identification of lipopigment

This article describes the histopathology of grossly normal mesenteric lymph nodes (MLNs) of New Zealand farmed red deer (Cervus elaphus). Eighty MLNs were sourced from 10 deer from 5 North Island herds and 5 South Island herds classified as low risk and high risk of Mycobacterium avium subspecies paratuberculosis (MAP) infection, respectively. Fixed sections were stained with hematoxylin and eosin; Ziehl-Neelsen; and, selectively, periodic acid-Schiff, Perl's, and Sudan black. Positive Ziehl-Neelsen stain, follicular hyperplasia, capsular eosinophil infiltration, focal granulomas, foci of macrophages containing lipopigment, parasitic granulomas, and calcified foci are described and severity graded where appropriate. Animal age, sex, and herd of origin are variably associated with the presence of one or more features. Trabecular fibrosis and dilated edema-filled sinusoids are described. These observations allow differentiation between likely nonpathologic histologic features in deer MLNs and features possibly attributable to infection with a pathogen such as MAP.     

The structure of bovine secretory component

Bovine secretory component (SC) has been cleaved with trypsin into a series of fragments and their N-terminal amino acid sequences have been determined. The close homology with the known sequence of human SC has enabled the sequential order of the fragments to be deduced. The results indicate that bovine SC consists of a single glycosylated polypeptide chain (Mr 74,000) folded into five globular immunoglobulin-like domains. A protein (Mr 94,000) has been isolated from detergent solubilised bovine epithelial membranes from liver, intestine and mammary gland. This membrane protein is specific for the binding of J-chain linked IgM and IgA dimers. It can be proteolytically cleaved into a water soluble SC-like portion and a detergent soluble hydrophobic portion. Bovine SC is therefore most likely to be the extracellular part of an epithelial receptor which mediates the transport of IgA dimers to mucosal surfaces. The various tryptic fragments from bovine SC have been shown to differ in their relative binding affinities for IgM and IgA dimers. The results imply that the first three domains of bovine SC are most involved in binding and domains 4 and 5 play subsidiary roles. Computerized prediction and modelling methods have been used to deduce possible tertiary and quaternary structures for SC. There are good indications that the molecule has an elonaged "zig-zag" structure stabilized by longitudinal inter-domain contacts. A model of SC bound to IgA dimer is presented.     

无核葡萄与中国野生葡萄杂种的胚挽救技术研究

 通过无核葡萄与中国野生葡萄杂交, 获得了4个杂交组合的后代植株, 确定了各杂交组合取胚珠培养的最佳时期。1Flame ×山葡萄; 2红宝石×爱莫无核; 3红宝石×北醇; 4爱莫无核×山葡萄在授粉后45 d取样培养效果较佳; 5长穗无核白×山葡萄授粉后30 d; 6无核白自交在授粉后35 d培养效果较佳。以NitSchs为基本培养基, 附加0.5 mg·L ^{- 1} 6-BA + 0.5 mg·L^-1 GA₃ + 2.5 mg·L ^{- 1} IBA + 0.1 mg·L^-1ZT, 适合于1、3、5号杂交组合; 而0.5 mg·L^-1 6-BA + 0.5 mg·L^-1 GA₃ + 2.0 mg·L^-1 IBA + 0.1 mg·L^-1ZT适合2、4、6号杂交组合; 胚萌发培养基为2.0 mg·L^-1 IBA + 1.0 mg·L^-1 6-BA +0.2 mg·L^-1 GA₃ , 适合1、2、3、5、6号杂交组合, 而爱莫×山葡萄在1.5 mg·L ^{- 1} IBA + 1.0 mg·L^-1 6-BA + 0.2 mg·L^-1 GA₃培养基上表现较佳, 生根培养基为1 /2MS基本培养基添加0.15 mg·L^-1 IBA + 0.02 mg·L^-1 6-BA, 它适合1号与5号组合, 0.10 mg·L^-1 IBA + 0.02 mg·L^-1 6-BA适合4号与6号组合。