电离辐射诱导在金属硫蛋白在小鼠免疫器官中的表达

观察了电离辐射对金属硫蛋白（ＭＴ）在免疫器官中表达的影响。采用放射性＾１０９Ｃｄ血红蛋白亲和分析法检测组织中ＭＴ含量。观察０．５、２、４、６ＧｙＸ射线全身照射后１６ｈ,及４Ｇｙ全身照射后０．５、２、４、８、１６、２４、４８、７２ｈ,昆明小鼠胸腺及脾脏中ＭＴ含量的变化。结果发现,在０．５～６Ｇｙ剂量范围内胸腺中ＭＴ含量剂量依赖性增高,其中４Ｇｙ和６Ｇｙ组有统计学意义（ｐ〈０．０５）。４ＧｙＸ射线照射后８～４８ｈ胸腺中ＭＴ含量显著增高（ｐ〈０．０５～ｐ〈０．００１）。然而,量效及时研究均未见脾脏中ＭＴ含量的变化。以上结果表明,Ｘ射线能诱导ＭＴ在免疫器官中表达,但表现出明显的组织特异性。     

Mercury and selenium concentrations in the internal organs of toothed whales and dolphins marketed for human consumption in Japan

Small cetaceans (toothed whales odontoceti and dolphins delphinidae) have been traditionally hunted along the coast of Japan and fresh red meat and blubber, as well as boiled internal organs such as liver, kidney, lung and small intestine, are still being sold for human consumption. We surveyed mercury contamination in boiled liver, kidney and lung products marketed in Japan between 1999-2001. The average +/- S.D. of total mercury (T-Hg) was 370 +/- 525 (range: 7.60 approximately 1980, n = 26) microg/g in liver, 40.5 +/- 48.5 (7.30-95.1, n = 15) microg/g in kidney and 42.8 +/- 43.8 (2.10-79.6, n = 23) microg/g in lung. A high correlation was observed between T-Hg and selenium (Se) concentrations in these organs, supporting the formation of a Hg-Se complex. The formation of a Hg-Se complex probably contribute to the detoxification of Hg for cetaceans and allows a very large accumulation of Hg in livers. The provisional permitted level of T-Hg in marine foods set by the Japanese Ministry of Health and Welfare is 0.4 microg/ g, and the provisional permitted weekly intake (PTWI) set by WHO is 5 microg/kg bw/week. The maximal T-Hg detected in boiled liver (1,980 microg/g) exceeds the permitted level by approximately 5,000 times and the consumption of only 0.15 g of liver exceeds the PTWI of 60 kg of body weight of the consumer, suggesting the possibility of an acute intoxication by T-Hg even after a single consumption of the product.     

^212Pb,^212Bi标记金属硫蛋白

研究了用２１２Ｐｂ、２１２Ｂｉ和２１２Ｐｂ－２１２Ｂｉ平衡混合物分别标记金属硫蛋白Ｃｄ－ＭＴ２及这些标记物在ＳｅｐｈａｄｅｘＧ－１００柱上的淋洗行为和衰变趋向。实验结果表明，在生理ｐＨ条件下，Ｃｄ－ＭＴ２首先与２１２Ｂｉ结合，其标记率接近１００％。     

肝癌腹水H22小鼠中^64Cu代谢和^125I—MT转运的研究

用＾６４Ｃｕ研究了铜在肝癌腹水小鼠中的代谢。研究结果表明，尾静脉注射的＾６４Ｃｕ在正常和肝癌小鼠中都先聚集在肝脏，在癌腹水小鼠肝脏中聚集的＾６４Ｃｕ要比正常小鼠的少，其它组织中＾６４Ｃｕ的分布也有一定的改变；癌细胞中的＾６４Ｃｕ占癌中的８５％以上。用ＳｅｐｈａｄｅｘＧ－７５柱分离小鼠肝脏匀浆物时，发现＾６４Ｃｕ主要与金属硫蛋白结合。在研究腹腔注射＾１２５Ｉ－（Ｃｄ，Ｚｎ）ＭＴ的转运时发现，在所观测     

Metal-binding proteins and peptides in the aquatic fungi Fontanospora fusiramosa and Flagellospora curta exposed to severe metal stress

The production of thiol-containing proteins/peptides and its role in metal-binding was examined in the aquatic hyphomycetes Fontanospora fusiramosa and Flagellospora curta exposed to Cu, Cd, or Zn at concentrations inhibiting the biomass production in 80%. Heat-treated cell-free extracts were separated by size-exclusion chromatography and the thiol and metal content in the fractions was determined. F. curta, the species tolerant to metals, showed higher absolute levels of thiol compounds, which bound higher amounts of Cu and Cd than F. fusiramosa. Peptides with very low molecular weight (<9 kDa), most likely glutathione and phytochelatins, were the major Cu- and Zn-binding components in both species of aquatic hyphomycetes. In most cases, proteins with high molecular weight (>26 kDa) were induced by metal ions and they were the major Cd-binding component in both species. Proteins with characteristics of metallothioneins were also induced by exposure to metals in both species, but they showed a minor role in metal-binding, suggesting they might have other functions in fungal cells.     

金属硫蛋白检测方法研究进展

金属硫蛋白是一种富含金属和半胱氨酸的低分子蛋白质,主要包括Ag、Au、Bi、Cd、Hg、Zn等硫蛋白,具有在体内可被金属和其他因素诱导合成的生物学特性。本文综述了目前7种常用的金属硫蛋白检测方法。     

A study of metal concentrations and metallothionein binding capacity in liver, kidney and brain tissues of three Arctic seal species

Arctic seals are known to accumulate relatively high concentrations of potential toxic heavy metals in their vital organs, such as livers and kidneys, as well as in their central nervous system. We therefore decided to determine whether mercury, copper, cadmium and zinc levels in liver, kidney and brain tissues of three Arctic seal species were associated with the intracellular metal-binding protein metallothionein (MT) as a sign of toxic exposure. Samples from four ringed (Phoca hispida), five harp (P.groenlandica) and five hooded (Cystophora cristata) seals taken during field trips to Central West Greenland (Godhavn) and the Barents Sea in the spring of 1999 were used for the present study. In all three seal species concentrations of mercury, zinc and copper were highest in the liver, except for cadmium which was highest in the kidneys. Metal concentrations increased significantly in the order: ringed seal < harp seal < hooded seal for both kidney and liver tissues. MT concentrations were highest in the kidneys and the concentrations increased in the order: ringed seal < hooded seal < harp seal. MT metal-binding capacity was highest in the kidneys for all three species and increased in the same order: ringed seals (2-10%) < hooded seals (8-15%) < harp seals (27-63%). We therefore suggest that there are species-specific differences in the sub-cellular handling of heavy metals which indicate differences in sensitivity and health implications. However, a larger sample size is needed in order to test the relationship between metal concentrations and MT up-regulation in order to decide which metals are the most important and to elucidate whether the MT binding capacity is sufficient to protect tissues (i.e. kidney) from metal toxicosis. MT with its binding capacity could be a useful marker for environmental exposure to metals and their potential toxicity in the Arctic.     

金属硫蛋白在辐射照射中的诱导及防护作用

金属硫蛋白(Metallothionein，简称MT)是一类广泛存在于生物体内的低分子量(约6—7ku)，富含半胱氨酸(30％)，能被诱导合成的金属结合蛋白。其生物功能广泛，主要参与微量元素的贮存、运输和代谢，有拮抗电离辐射，清除自由基等多种作用。介绍了MT的分类、MT基因结构、基因放大和基因调控，MT合成的辐射诱导及其机理以及MT在辐射照射中所起的保护作用。     

Optimization of new voltammetric method for the determination of metallothionein

Electrochemical determination of metallothioneins (MTs) is widely used for environmental studies. In this paper, a new procedure for the quantification of MT by square wave cathodic stripping voltammetry has been developed and optimized. The determination is based on the complexation of cisplatin and MT and the subsequent reduction of the complexes at the electrode. In order to achieve highest sensitivity and resolution of the peak, an optimization of the experimental parameters has been carried out using experimental design methodology (response surface). Seven chemical and physical parameters namely pH, cisplatin concentration, buffer concentration, deposition potential, square wave frequency, amplitude of the pulse and step potential have been optimized. Method characterization has been performed, leading to a detection limit of 6×10⁻¹² mol l⁻¹. This sensitivity is comparable to that of immunoassay, inducing that this procedure may also be used for MT quantification in tissue or serum.