紫贻贝金属硫蛋白对小鼠体内镉富集的拮抗及排出功效研究

目的考察紫贻贝金属硫蛋白(metallothionein,MT)对小鼠体内Cd~(2+)的拮抗及排除功效。方法采用0.5 mg/L CdCl_2饲喂小鼠,建立Cd~(2+)染毒小鼠模型;设立正常对照、CdCl_2模型、MT(50、75、100 mg/(kg·d))和依地酸二钠钙(75 mg/(kg·d))组,连续给药3 d、停止4 d,持续30 d后,分析小鼠生理指标、Cd~(2+)含量、抗氧化能力及肠道菌群组成。结果与正常组相比,模型小鼠体重、肝脏和脾脏重量及其系数显著降低(P0.05),依地酸二钠钙和较高剂量MT给药,表现出显著改善小鼠生理指标作用。模型小鼠全血、肝脏及骨中Cd~(2+)含量显著增加(P0.05),依地酸二钠和MT给药对体内Cd~(2+)排除显著(P0.05)。相比正常组和模型组,MT对小鼠体内总抗氧化能力(total antioxidant capacity,T-AOC)和丙二醛(malondialdehyde,MDA)含量具有显著改善作用(P0.05)。与正常组相比,Cd~(2+)染毒显著影响小鼠肠道正常菌群关系,造成菌群丰度和多样性减少;而MT对染毒小鼠肠道菌群结构、微生物多样性及丰度,均具有一定恢复作用。结论 MT具有拮抗Cd~(2+)体内富集及排出功效,其机制可能通过修复Cd~(2+)氧化损伤、减少过氧化产物水平及调节肠道菌群结构等途径实现。     

酵母源金属硫蛋白对慢性汞中毒小鼠排汞及肝脏损伤修复作用

目的:探讨两种具自主知识产权酵母源金属硫蛋白(metallothionein,MT)(MT-1、MT-2)对慢性汞中毒小鼠排汞及汞致肝脏损伤的修复作用。方法:慢性汞中毒模型通过实验小鼠自由饮用氯化汞去离子水溶液构建,经连续灌胃给予二巯基丙磺酸钠及不同剂量酵母源MT(0.16、0.40、0.80 mg/(kg·d))28 d后,测定实验小鼠体质量、肝脏脏器系数、血液及肝脏汞含量、4项血常规(白细胞计数、红细胞计数、血小板计数、血红蛋白含量)、肝功能指示指标并观察慢性汞中毒小鼠肝脏组织病变程度。结果:与模型对照组比较,各灌胃给药组小鼠体质量均不同程度提高,肝脏脏器系数显著下降(P0.05),血液及肝脏汞含量显著下降(P0.05),白细胞、红细胞、血红蛋白含量及血小板计数均有不同程度恢复,其恢复效果与剂量呈正相关。与模型对照组比较,各酵母源MT灌胃给药组小鼠血清谷丙转氨酶及谷草转氨酶含量均有所下降,且综合肝脏组织病理学染色切片结果,酵母源MT可修复汞中毒小鼠肝脏组织,使水肿肝脏细胞恢复其正常形态,减少细胞间炎性浸润现象,且两种酵母源MT修复受损肝脏的能力与剂量呈正相关,高剂量酵母源MT对受损肝脏的修复效果更佳。结论:综合各项检测结果,两种酵母源MT对慢性汞中毒小鼠具有良好的排汞及修复汞致肝脏损伤效果,且酵母源MT-1对慢性汞中毒小鼠排汞及修复受损肝脏组织的效果好于酵母源MT-2及二巯基丙磺酸钠。     

信阳米酒酵母金属硫蛋白的分离纯化及鉴定

从信阳米酒中分离酵母菌,经CuSO4诱导、超声波破碎酵母细胞,然后从无细胞抽提液中分离纯化Cu-MT,该MT由60个氨基酸组成,其中半胱氨酸为6.2%,相对分子质量7×103.     

The effects of decreasing heavy metal concentrations on the biota of Buttle Lake, Vancouver Island, British Columbia

Since 1966, a copper-lead-zinc mine operated by Westmin Resources Limited has been a source of heavy metal input into Buttle lake. Metal levels increased in the lake, peaking in 1980/1981; thereafter improved treatment and collection systems at the mine site have resulted in steadily decreasing metal levels throughout the lake system. The increase in metal concentrations in the lake water was accompanied by increased metal concentrations in salmonid muscle and liver tissues, by elevated levels of hepatic metallothionein and by declines in both species diversity and population for phytoplankton, periphyton and zooplankton. However, recovery of the biota of Buttle lake with decrease in metal concentrations has not followed a simple reversal of the earlier trends.While metal levels in rainbow trout muscle tissue have improved significantly, copper and cadmium liver tissue levels remain significantly higher than for the control lakes. Hepatic metallothionein levels in rainbow trout have declined steadily from a maximum of 269 ± 23 nmol/g in 1981 to a low of 64 ± 22 nmol/g in 1985, which is similar to the control lake.Interspecies comparison of muscle and liver tissue levels both for Buttle lake and for uncontaminated British Columbia lakes found that rainbow trout (Oncorhynchus mykiss), cutthroat trout (Oncorhynchus clarki) and Dolly Varden char (Salvelinus malma) respond differently to metals in the environment. It is apparent that trends in rainbow trout data should not be generalized to include all three groups.As metal concentrations decreased, the phytoplankton community began to change so that beginning in 1983 and continuing well into 1985, a continuous phytoplankton bloom consisting of a virtual monoculture of Rhizosolenia eriensis was present throughout the lake. Accompanying the bloom was a scarcity of zooplankton. However, as levels of R. eriensis peaked in 1985, zooplankton and phytoplankton diversity and species number are improving as previously dominant species begin to reappear.     

不同重金属胁迫蔬菜产生金属硫蛋白的同源性检测

目的 对不同重金属胁迫蔬菜产生金属硫蛋白(金属硫组氨酸三甲基内盐)进行同源性检测。方法 用Cd-MT免疫家兔产生IgG后, 用不同浓度硫酸铜、乙酸铅、氯化钴、氯化汞等重金属胁迫萝卜幼苗、油白菜和油麦菜诱导产生金属硫蛋白, 通过免疫印迹检测其同源性。结果 Cd-MT与重金属胁迫三种蔬菜所产生的金属硫蛋白具有同源性; 不同浓度的重金属对幼苗中MTs表达量有影响。结论 Cd-MT诱导家兔产生的IgG可用于农产品中重金属污染的检测。     

Metals in aquatic ecosystems: mechanisms of uptake,accumulation and release‐Ecotoxicological perspectives

Metals are essential cofactors for bio‐chemical processes, including oxidative phosphorylation, gene regulation and free‐radical homeostasis. Abnormalities in metal ions concentration in organisms, lead towards the eco‐physiological hazards in the aquatics. In aquatic organisms, metal absorption involves transfer of metals to the circulatory system following : uptake by the apical membrane; movement through the cell as well as interaction with intracellular ligands and efflux across the basolateral membrane. Sequestration of metals in an immobilized form occurs throughout the various tissues and organs involved in pathways for metal uptake, transport, utilization and release. Metallothioneins, metal binding proteins, regulate the essential metals (Cu, Zn), detoxify the toxic metals (Cd, Hg) and play key role to the sequestering metals. Plasma proteins play the central role in metal transport in the vertebrates. Besides, blood cells in aquatic invertebrates, hemocytes in mollusks concentrate a variety of metals. Aquatic organisms utilize renal, digestive pathways and diapedesis for the excretion of a variety of metals.

This paper briefly reviews current information about the processes associated with metal uptake, transport, release, accumulation in the aquatic organisms and discuss about eco‐toxicological aspect of bio‐accumulation and suggest further necessary researches for future endeavor.     

A Zn(II)-glycine complex suppresses UVB-induced melanin production by stimulating metallothionein expression

Oxidative stress caused by ultraviolet (UV) radiation generates reactive oxygen species (ROS) in the skin, induces the secretion of melanocyte growth and activating factors from keratinocytes, which results in the formation of cutaneous hyper-pigmentation. Thus, increasing the anti-oxidative ability of skin cells is expected to be a good strategy for skin-lightening cosmetics. Metallothionein (MT) is one of the stress-induced proteins and is known to exhibit a strong anti-oxidative property. We previously reported that a zinc(II) complex with glycine (Zn(II)(Gly)(2)) effectively induces MT expression in cultured human keratinocytes. To determine its potential as a new skin lightening active, we examined whether Zn(II)(Gly)(2) regulates the release of melanocyte-activating factors from UVB-irradiated keratinocytes and affects melanin production in a reconstructed human epidermal equivalent. Conditioned medium from UVB-irradiated keratinocytes accelerated melanocyte proliferation to 110%, and that increase could be prevented by pre-treatment with Zn(II)(Gly)(2). In addition, Zn(II)(Gly)(2) significantly reduced both the production of prostaglandin E(2) and proopiomelanocortin expression in UVB-irradiated keratinocytes. Zn(II)(Gly)(2) also decreased melanin production in a reconstructed human epidermal equivalent. These results indicate that MT-induction in the epidermis effectively up-regulates tolerance against oxidative stress and inhibits the secretion of melanocyte growth and activating factors from keratinocytes. Thus, Zn(II)(Gly)(2) is a good candidate as a new skin-lightening active.