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INTRODUCTIONATislowKWCys-rich(aboutonethird)metal-bindingprotein,lackofaromaticaminoacidresidues.AThasbeenfoundinkidneysandliversofmanymammals,andalsoininvertebrates,microorganismsandplants.ThepresenceofanAT-likeproteinhasbeenfoundinanumberofaquaticorganisms,includingtheplaice(Overnelletal.,1977),rock-fish(Olafsonetal.,1974),goldfish(Marafant,1976),andcrabandshrimp(Olafsonetal.,1979).AThasbecomethesubjectofgreatInterestinrecentyearsduetotheirwideexistenceandmetalaffinity.Scientistsha… 相似文献
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A small amount of heavy metal binding protein, identified by BioRad Protein Assay, has been isolated from the adult brine
shrimp,Artemia franciscanus. This protein has an apparent molecular weight between 6000 to 9000 dalton. a UV absorption peak at 260 instead of 280 nm
like most proteins; and has high affinity towards binding with radioactive labeled109Cd. These characteristics are similar to that of metallothioneins reported for many vertebrate and invertebrate, marine and
terrestrial animals. After the brine shrimp is exposed to a small amount of Cd2+ for 24 h, a large amount of metallothionein can be isolated, showing the inducibility of this detoxifying protein in the
adultArtemia in a short period of time. 相似文献
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Different sizes of Littorina littorea were collected from four areas in the Firth of Clyde, Scotland. Their metallothionein (MT) and heavy metal concentrations were analysed using the Silver Saturation Method and Atomic Absorption Spectrophotometry, respectively. Concentrations of MT, Cd and Zn (as μg g−1 dry soft-body weight) generally decreased with an increase in size of L. littorea. MT concentrations were better correlated with Cd than with Zn or Cu concentrations. Nevertheless, MT and the metals in periwinkles (as μg individual−1) increased significantly with increasing size. Concentrations of MT and the metals among the sampling areas were compared at a standardised soft-body weight (10 mg). The results from Discriminant Analysis based on all metal concentrations indicate that Largs is different from the other areas and characterised by high Fe concentrations in L. littorea. The problems and differences in using either soft-body weight or shell length as independent variable for size-standardisation are discussed. 相似文献
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Expression of Mammalian Metallothionein-I Gene in Cyanobacteria to Enhance Heavy Metal Resistance 总被引：2，自引：0，他引：2
Metallothionein (MT) from mammals is a low molecular weight (about 6–7 KD), and cystein-rich (20 cystein per molecular) protein (Vallee, 1991). So MT has the strong binding ability of metal such as Cd, Hg and Pd. Wild-typed cyanobacteria have their own metallothionein-like proteins, which are of low cysteine content and have weak ability to bind heavy metal. Therefore, it is imperative to transfer the MT-I gene from mammal into cyanobacteria cell for the absorption and accumulation of heavy metals in aqueous system including marine and lake ( Misra and Gedamu, 1989). We inserted the MT-I cDNA gene after the strong promoter PpsbA or Psmt into the intermediary vector pRL-439, and then pRL-MT was ligated with shuttle vector pKT-210 (a shuttle vector pDC-08 was used at an earlier time) to construct the shuttle expression vector pKT-MT. (The MT-I mutant -KKS- also was selected as aim gene.) Then the constructed vector was introduced into cyanobacterium Anabaena sp. PCC7120, Synechocystis sp. PCC6803 and Synechococcus sp. PCC7942 with triparental conjunctive transfer (Bryant, 1994). The expression efficiency is about 1%. We also used homologous recombination vector pTZ18-8 to introduce MT-I cDNA into chromosomes in cyanobacteria and got higher expression efficiency. Metal tolerance tests show that the transgenic cyanobacteria acquire metal resistance up to 60 μmol/g CdCl2 and expression efficiency up to 1045 μg MT/g fresh cells according to the data of ELISA. 相似文献
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Zosteramarina, a monocotyledonous angiosperm, is one of themost important seagrass species. To investigate the salt-tolerancemechanismand discover salt-tolerant genes in Z. marina, a cDNA library was constructed. Single-pass sequencing of the 5' ends of 4 081 clones yielded 4 002 high quality expressed sequence tags (ESTs), which were assembled into 241 contigs and 1 673 singletons, representing 1 914 unigenes. The average length of the ESTs was 582 bp, with sizes ranging from100-1 500 bp. Basic Local Alignment Search Tool (BLASTX) analysis revealed that 1 664 unigenes had significant homology to known genes in the National Center for Biotechnology Information (NCBI) non-redundant (nr) database (E-value≤5-10). Among them, the twomost abundant genes encoded metallothionein (157 ESTs) and chlorophyll a/b-binding protein (38 ESTs), accounting for 7.1% and 1.7% of the total ESTs, respectively. Using Kyoto Encyclopedia of Genes and Genomes (KEGG), 1 462 unigeneswere assigned to 1 161 pathways (E-value≤5-10). A total of 938 unigenes were assigned Gene Ontology (GO) terms based on the GO hierarchy analysis, and InterProScan searches recognized 1 003 InterPro families. Three genes formetallothionein in Z. marina that belonged to Class II was identified. Results of this study will improve understanding of the molecular mechanisms of saline tolerance in Z.marina. 相似文献
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重金属对扁额细首纽虫金属硫蛋白的影响 总被引：1，自引：0，他引：1
生物体内金属硫蛋白含量变化,可作为环境中重金属污染的生物标志物.通过暴露实验研究了扁额细首纽虫Cephalothrix simula暴露在不同浓度的铜,锌和镉溶液96 h,其体内金属硫蛋白含量的变化规律.结果表明3种重金属离子的胁迫作用均导致金属硫蛋白含量增加,在实验初期(6～24 h),金属硫蛋白含量达到高峰;金属硫蛋白含量与暴露溶液金属浓度具有明显的剂量～效应关系,金属离子浓度越高,金属硫蛋白含量越高;锌离子诱导金属硫蛋白合成的作用大于铜、镉离子. 相似文献
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海洋无脊椎动物金属硫蛋白研究进展 总被引：4，自引：0，他引：4
金属硫蛋白(metallothionein,MT)在海洋无脊椎动物中广泛存在,对多种重金属具高亲和性,在生物体内重金属解毒、必需金属离子调控和体内自由基清除等方面具有重要作用。综述了近几十年来海洋无脊椎动物金属硫蛋白的研究进展,着重介绍了软体动物(Mollusca)、节肢动物(Arthropoda)以及棘皮动物(Echinodermata)金属硫蛋白的研究现状,分析了无脊椎动物金属硫蛋白的特点,对海洋无脊椎动物金属硫蛋白的研究进行了总结。近年来,海洋无脊椎动物金属硫蛋白的研究热点主要集中在金属硫蛋白不同组织定位及蛋白序列多态性对其功能的影响、异构体在动物体内发挥的不同作用等。我国近海的重金属污染日益严峻,金属硫蛋白在重金属生物毒理效应等方面发挥重要作用,海洋无脊椎动物金属硫蛋白在生态毒理领域的研究日趋受到重视,对海洋无脊椎动物金属硫蛋白的研究亟待加强。 相似文献
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