牛Ⅱ型链球菌van B2蛋白的原核表达及纯化

目的原核表达并纯化牛Ⅱ型链球菌(Streptococcus bovis biotypeⅡ)van B2蛋白。方法采用PCR法从牛Ⅱ型链球菌基因组DNA中扩增van B2基因,克隆至原核表达载体pET-28a(+)中,构建重组表达质粒pET-28a-van B2,转化大肠杆菌Rossata(DE3),IPTG诱导表达。表达的重组蛋白经Ni柱亲和层析纯化后,进行SDS-PAGE及Westernblot分析。结果 PCR扩增获得597 bp的van B2基因片段;重组表达质粒pET-28a-van B2经双酶切及测序证明构建正确;表达的重组van B2蛋白相对分子质量约为29 000,主要以可溶性形式表达;纯化的重组蛋白纯度为70%,可被小鼠抗牛链球菌血清Ⅱ型多克隆抗体特异性识别。结论原核表达并纯化了牛Ⅱ型链球菌van B2蛋白,为van B2基因的耐药性研究奠定了物质基础。     

药剂混配对B型烟粉虱药效及烟草安全性评价

利用试管药膜法测定了啶虫脒等药剂及其混配对B型烟粉虱成虫的毒力,利用烟草植株测定了哒螨灵、啶虫脒及混配对B型烟粉虱的药效以及对烟草植株的安全性.结果显示,啶虫脒在3种新烟碱类药剂中显示了较高毒力,LC50为7.119 5mg/L,哒螨灵与啶虫脒1:1与2:1混配显示了一定的拮抗作用,4:1与8:1混配显示出了一定的相加...     

Molecular profiling of Jatropha curcas L. collected from different geographical locations of India

The present study surveys the morphological, biochemical and molecular diversity in 30 accessions of Jatropha collected from different states of India by using random amplified polymorphic DNA (RAPD), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and isozyme analysis. The genotyping data were used to understand the relationships among accessions and to identify genetic diversity as a means for genetic improvement of Jatropha. Out of 37 decamer primers used, 18 yielded polymorphic banding pattern. In total, 126 different DNA bands were reproducibly obtained, out of which 81 were polymorphic. SDS-PAGE of seed, leaf and callus resolved into 18, 12 and 7 bands, while no biotype-specific band was found in leaf and callus protein profile. Cluster analysis of both RAPD and SDS-PAGE data produced two major clusters.     

Physicochemical, thermal and functional characterisation of protein isolates from Kabuli and Desi chickpea (Cicer arietinum L.): a comparative study with soy (Glycine max) and pea (Pisum sativum L.)

BACKGROUND: Chickpea (Cicer arietinum L.) seeds are a good source of protein that has potential applications in new product formulation and fortification. The main objectives of this study were to analyse the physicochemical, thermal and functional properties of chickpea protein isolates (CPIs) and compare them with those of soy (SPI) and pea (PPI) protein isolates. RESULTS: Extracted CPIs had mean protein contents of 728–853 g kg^?1 (dry weight basis). Analysis of their deconvoluted Fourier transform infrared spectra gave secondary structure estimates of 25.6–32.7% α‐helices, 32.5–40.4% β‐sheets, 13.8–18.9% turns and 16.3–19.2% disordered structures. CPIs from CDC Xena, among Kabuli varieties, and Myles, among Desi varieties, as well as SPI had the highest water‐holding and oil absorption capacities. The emulsifying properties of Kabuli CPIs were superior to those of PPI and Desi CPIs and as good as those of SPI. The heat‐induced gelation properties of CPIs showed a minimum protein concentration required to form a gel structure ranging from 100 to 140 g L^?1. Denaturation temperatures and enthalpies of CPIs ranged from 89.0 to 92.0 °C and from 2.4 to 4.0 J g^?1 respectively. CONCLUSION: The results suggest that most physicochemical, thermal and functional properties of CPIs compare favourably with those of SPI and are better than those of PPI. Hence CPI may be suitable as a high‐quality substitute for SPI in food applications. Copyright © 2011 Society of Chemical Industry     

Identification of biomarkers of meat tenderisation and its use for early classification of Asturian beef into fast and late tenderising meat

BACKGROUND: The objective of this work was to study the post‐mortem evolution of potential biomarkers (µ‐calpain activity and proteolytic profile) of meat tenderisation in bovine longissimus dorsi (LD) muscle from several biotypes coming from two beef breeds (‘Asturiana de los Valles’ and ‘Asturiana de la Montaña’) and showing different levels of muscular hypertrophy (mh/mh, mh/+, + /+). RESULTS: LD samples were taken at 2, 12, 24 and 48 h and 3, 7, 14 and 21 days post‐mortem. The presence of muscular hypertrophy produced a faster rate of pH decline, faster exhaustion of µ‐calpain activity and earlier occurrence of proteolytic changes. Changes in the electrophoretic pattern of some peptides from sarcoplasmic (glyceraldehyde‐3‐phosphate dehydrogenase) and myofibrillar (troponin T and troponin I) muscle extracts within the first 24 h significantly correlated with meat toughness and allowed accurate discrimination of meat products into two groups: (1) fast tenderising meat, coming from mh‐biotypes, and (2) late tenderising meat, from normal (+/+) biotypes. CONCLUSION: Early monitoring (within 24 h after slaughter) of selected biomarkers in LD muscle allowed accurate prediction of ultimate meat toughness and could be used in the meat industry as a tool for early classification of beef into fast and late tenderising meat. Copyright © 2012 Society of Chemical Industry     

Large-scale immobilization of lipase fromPseudomonas fluorescens biotype I and an application for sardine oil hydrolysis

Large-scale production of thermostable lipase fromPseudomonas fluorescens biotype I was carried out in a fermenter with an antifoaming agent and physical deforming treatments. After cultivation, heat treatment was applied to kill the bacteria and to inactivate other enzmes. Large-scale immobilization of the lipase to a macroporous weak-anion exchange resin was performed with a lipase solution that had an ionic strength of less than 0.1 and an ethanol concentration of 50%. Almost all eicosapentaenoic acid and docosahexaenoic acid were liberated continuously from sardine oil by the immobilized lipase in a countercurrent fluidized-bed reactor. The cost of enzyme used in the reactor has been compared with a process in which soluble lipase fromCandida rugosa was used.     

Serine proteases-like genes in the asian rice gall midge show differential expression in compatible and incompatible interactions with rice

The Asian rice gall midge, Orseolia oryzae (Wood-Mason), is a serious pest of rice. Investigations into the gall midge-rice interaction will unveil the underlying molecular mechanisms which, in turn, can be used as a tool to assist in developing suitable integrated pest management strategies. The insect gut is known to be involved in various physiological and biological processes including digestion, detoxification and interaction with the host. We have cloned and identified two genes, OoprotI and OoprotII, homologous to serine proteases with the conserved His(87), Asp(136) and Ser(241) residues. OoProtI shared 52.26% identity with mosquito-type trypsin from Hessian fly whereas OoProtII showed 52.49% identity to complement component activated C1s from the Hessian fly. Quantitative real time PCR analysis revealed that both the genes were significantly upregulated in larvae feeding on resistant cultivar than in those feeding on susceptible cultivar. These results provide an opportunity to understand the gut physiology of the insect under compatible or incompatible interactions with the host. Phylogenetic analysis grouped these genes in the clade containing proteases of phytophagous insects away from hematophagous insects.     

DNA typing of populations of phylloxera (Daktulosphaira vitifoliae (Fitch)) from Australian vineyards

A comparative analysis of six populations of Daktulosphaira vitifoliae , the insect grape phylloxera, from Australia was made using the Random Amplified Polymorphic DNA typing technique. The populations analysed fell into three distinct groups with similarity between groups ranging from 48% to 86%. The significance of these groupings is discussed with reference to the history of phylloxera in Australia, recommendations on rootstock use and quarantine.     

In vitro assessment of grapevine resistance to two populations of phylloxera from Australian vineyards

A perlite-based medium is described for in vitro cocultivation of phylloxera with micropropagated vines. Using this system, as well as cocultivations on excised primary roots, six vine types were screened for resistance to one or two populations of phylloxera (SRU-1 or VWL-1) sourced from different Australian vineyards. When inoculated with VWL-1 phylloxera, V. vinifera cv. Shiraz was rated as susceptible, Ramsey as resistant, Schwarzmann, V. riparia and Börner as highly resistant and V. rotundifolia as immune. When inoculated with SRU-1 phylloxera, both V. vinifera and Schwarzmann were rated as susceptible. The potential use of these in vitro methods for rootstock resistance screening and determination of phylloxera biotypes is discussed. Phylloxera behaviour and root responses observed in vitro are also described.     

稻田杂草对除草剂的抗性及其防治

本文收集了至目前为止世界各地稻田已对除草剂产生抗性的杂草种类及其分布、多抗性与交互抗性,讨论了稻田杂草抗性的治理。