不同脱除剂对暂养紫贻贝体内重金属Cd2+的脱除效果

重金属镉(Cd2+)污染是影响双壳贝类食用安全的重要因素之一。以紫贻贝为研究对象,探索不同脱除剂对暂养紫贻贝体内重金属Cd2+的脱除效果。将染Cd2+的紫贻贝暂养在含不同脱除剂天然海水中,定期更换暂养水体并取样,采用原子吸收法测定贻贝中Cd2+含量。实验采用硒代蛋氨酸、硒化卡拉胶、亚硒酸钠、EDTA-FeNa、EDTA-ZnNa₂、EDTA、氯化亚铁、氯化铁、氯化锌、β-葡聚糖、肽聚糖及葡萄糖酸钙作为脱除剂,评价暂养过程中其对紫贻贝体内重金属Cd2+的脱除效果。结果显示,60和120 mg/L硒化卡拉胶、160 mg/LEDTA-CaNa₂和500 mg/L β-葡聚糖净化处理后,对紫贻贝体内Cd2+具有良好的脱除效果(p<0.05),其脱除率分别为43.6%、37.2%、41.6%和44.6%。     

蛋白水解肽-Fe~(2+)配合物对紫贻贝体内Cd脱除的影响

为探讨紫贻贝体内重金属Cd残留的脱除方法,采用海水中添加制备的蛋白水解肽-Fe2+配合物(TPH-Fe2+)进行暂养,检测贻贝不同组织器官中Cd含量变化情况。结果显示,贻贝不同器官中Cd富集量,依次为内脏团鳃后闭壳肌外套膜前闭壳肌,且在0~10 d自然净化过程中,无显著性下降趋势(P0.05)。添加10 mg/L TPH-Fe2+净化处理,对贻贝内脏团及鳃中Cd含量无显著性影响;添加15~25 mg/L TPH-Fe2+净化处理贻贝4 d后,内脏团、鳃、前后闭壳肌及外套膜中Cd含量均有不同程度下降(P0.05);20 mg/L TPH-Fe2+净化10 d后,贻贝不同器官中Cd脱除率表现为鳃内脏团外套膜前后闭壳肌,最高脱除率分别为41.00%、37.43%、29.81%和29.01%,与25 mg/L TPH-Fe2+净化处理组无显著性差异(P0.05)。研究表明,蛋白水解肽-Fe2+配合物有效脱除贻贝体内Cd残留,可作为一种双壳贝类养殖饲料添加剂加以应用。     

紫贻贝(Mytilus edulis)不同组织对镉的生物富集及释放特征

目的:探索紫贻贝不同器官对镉(Cd)的富集吸收及释放特征。方法:以紫贻贝为研究对象,采用静态水交换法进行染毒,原子吸收光谱检测Cd在紫贻贝不同器官中的含量变化情况。结果:富集第15 d,紫贻贝内脏团、前闭壳肌、后闭壳肌、外套膜和鳃中,Cd含量依次为145.560、11.826、28.143、22.394、66.113 mg/kg。4种器官对Cd的吸收速率常数(k),在富集初期较高、中期有所减弱、后期再次升高;生物富集系数(BCF)随暴露Cd浓度增加而逐渐减小,且均表现为内脏团鳃后闭壳肌外套膜前闭壳肌。4种器官Cd量与富集时间之间关系,均符合Harris模型(Y=1/(a+b Xc)),拟合R2范围为0.9286~0.9890。在释放阶段,4种器官中Cd含量均未表现出显著性下降趋势(p0.05)。结论:紫贻贝对Cd具有较强的生物富集能力,而其自然代谢释放能力较弱,为典型Cd净积累型生物。     

海藻糖和褐藻胶寡糖对冻藏紫贻贝品质的影响

为探讨海藻糖和褐藻胶寡糖的低温保护活性,以紫贻贝为对象,评价了海藻糖和褐藻胶寡糖处理对冻藏紫贻贝肉品质特性的影响。结果发现,在6周冻藏过程中,相比于蒸馏水和空白组,海藻糖和褐藻胶寡糖显著(p0.05)降低了紫贻贝肉解冻损失率,褐藻胶寡糖组解冻损失率低至14.28%,并维持了较好的弹性和咀嚼性等特性,同时有效抑制了紫贻贝肉中菌落总数的快速增加。此外,两种糖类浸泡处理维持了较好的肌原纤维蛋白Ca~(2+)-ATPase活力,肌原纤维蛋白Ca~(2+)-ATPase活力在0.019～0.021U/mgprot范围内,三个处理组之间并无显著性差异(p0.05)。微观观察发现,海藻糖和褐藻胶寡糖处理紫贻贝,组织结构相对较为完整、致密,细胞间隙冰晶颗粒面积较小,其组织结构保护作用明显优于焦磷酸钠处理效果。海藻糖和褐藻胶寡糖可作为一种高效的低温保护剂,用于保持紫贻贝及其制品品质及延长冻藏产品货架期。     

硒化卡拉胶寡糖的制备及抗氧化活性研究

以卡拉胶寡糖为原料、硒元素为螯合配体,以DPPH自由基清除活性为响应值,采用单因素试验及响应面分析法,优化硒化卡拉胶寡糖的制备工艺,进而分析其对羟基自由基、超氧阴离子自由基、DPPH自由基的清除能力及还原力。结果表明,硒化卡拉胶寡糖的最佳制备工艺为:反应pH6,反应时间3.48h,亚硒酸钠与卡拉胶寡糖比例1∶2和反应温度60℃。此条件下,经验证试验证实制备硒化卡拉胶寡糖对DPPH自由基清除率为96.48%,与模型预测值相对误差为0.58%。此外,体外抗氧化活性测试发现,硒化卡拉胶寡糖具有较强的清除自由基能力及还原能力,且其抗氧化活性与硒化物浓度成正向线性关系,抗氧化活性显著优于单纯的卡拉胶寡糖。     

κ-卡拉胶寡糖对小鼠皮肤成纤维细胞增殖和胶原分泌的影响

目的研究κ-卡拉胶寡糖对小鼠皮肤成纤维细胞增殖和胶原分泌的影响。方法原代培养小鼠皮肤成纤维细胞,传代培养后加入不同浓度的κ-卡拉胶寡糖作用,应用细胞计数法,四甲基偶氮唑盐(MTT)比色法,检测κ-卡拉胶寡糖对皮肤成纤维细胞增殖的影响,ELISA法检测κ-卡拉胶寡糖对皮肤成纤维细胞分泌Ⅰ型、Ⅲ型胶原蛋白的影响。结果 12.5μg/mL 100μg/mL范围内,各组κ-卡拉胶寡糖对小鼠皮肤成纤维细胞均有一定促进增殖作用,其中以100μg/mL时最为显著(P<0.01)。用25μg/mL和50μg/mLκ-卡拉胶寡糖处理小鼠皮肤成纤维细胞后,与对照组相比,Ⅰ型胶原蛋白分泌明显增加(P<0.05);12.5μg/mL 100μg/mL范围内,各组κ-卡拉胶寡糖均显著促进Ⅲ型胶原蛋白分泌(P<0.05)。结论κ-卡拉胶寡糖能有效促进小鼠皮肤成纤维细胞增殖和胶原分泌。     

壳寡糖防止苹果果汁褐变的机理

以红富士苹果为材料,分别测定不同质量浓度壳寡糖(OCS)对果汁中自由基的清除作用,对超氧化物歧化酶(SOD)、谷胱甘肽过氧化酶(GSH-Px)、过氧化物酶(POD)、过氧化氢酶(CAT)4种抗氧化酶酶活性和多酚氧化酶(PPO)酶活性以及与抗氧化有关物质(还原型VC和总酚)含量的影响。结果表明:壳寡糖对果汁中自由基的清除作用比较明显,尤其在2mg/mL和4mg/mL的质量浓度条件下可以较好的抑制O2-.的产生。壳寡糖可以明显提高抗氧化酶的酶活性,并且降低PPO的酶活性。壳寡糖对果汁中还原型VC和多酚含量的变化无显著性影响。提示壳寡糖可以提高抗氧化酶的活性,降低果汁中自由基的含量,抑制PPO的酶活性,从而抑制苹果果汁加工中褐变的发生。     

硒化魔芋葡甘寡糖的合成及其抗氧化活性

为获得高硒含量的葡甘寡糖,以天然魔芋葡甘聚糖经酶解制备的魔芋葡甘寡糖为原料,合成硒化魔芋葡甘寡糖,采用傅里叶变换红外光谱和核磁共振波谱对其结构进行表征,采用电感耦合等离子体质谱法检测其硒含量;利用体外抗氧化实验研究其抗氧化活性。结果表明：合成的硒化魔芋葡甘寡糖为葡甘寡糖亚硒酸酯,硒含量达5.9 g/kg,远高于富硒土壤种植魔芋提取的天然多糖;硒化魔芋葡甘寡糖对羟自由基具有很好的清除作用,可作为理想的抗氧化有机硒食品原料。     

硒化卡拉胶预混料的研制及强化小麦粉制品中硒的测定

以GB 14880-94中规定的谷物食品强化硒化卡拉胶(硒酸酯多糖)标准下限值的1.1倍(154 μg/kg或0.154 mg/kg)为基准,研究了两种用于小麦粉中强化硒的"硒化卡拉胶预混料",开展了硒强化小麦粉的中试试验、制作了面条及面包,并对各产品的硒含量和混合均匀度进行了测定分析,得到如下主要结论:以"硒化卡拉胶预混料"为强化原料,采用配粉技术和随动投加系统生产硒强化小麦粉是可行的;产品中硒元素的变异系数(CV)≤10%,混合均匀度符合要求;与普通小麦粉比较,中试生产的硒强化小麦粉在外观、气味和色泽等方面无不良变化,强化硒化卡拉胶,可显著增加小麦粉及其面制品(面条、面包)中硒的含量,提高了小麦粉及面制品的营养价值;而且,面制品的常规加工工序如和面、压片、干燥、烘焙对硒化卡拉胶的影响很小,硒在终产品中得到了较好的保存.     

不同贮藏温度下鲜切紫甘薯褐变相关因素研究

为研究鲜切紫甘薯的褐变条件与机理,本文对不同贮藏温度下(4和12℃)的鲜切紫甘薯的褐变程度、褐变相关酶活力以及褐变底物酚类物质进行分析。结果表明,12℃贮藏组的鲜切紫甘薯褐变度始终显著高于4℃贮藏组(P<0.05)。贮藏期间,褐变重的鲜切紫甘薯多酚氧化酶(Polyphenol oxidase,PPO)和过氧化物酶(Peroxidase,POD)活性更高,丙二醛(Malondialdehyde,MDA)含量更多。2~8 d,不同贮藏温度下鲜切紫甘薯绿原酸和阿魏酸含量显著不同(P<0.05),因此推断褐变相关酶活性、膜脂过氧化程度以及酚类物质含量可能是引起鲜切紫甘薯褐变的关键因素。通过相关性分析,多酚氧化酶(PPO)和过氧化物酶(POD)是引起鲜切紫甘薯褐变的关键酶。绿原酸和阿魏酸是鲜切紫甘薯褐变的主要底物。     

Manganese, nickel, selenium and cadmium in molluscs from the Magellan Strait, Chile.

The concentrations of manganese, selenium, nickel and cadmium were determined in 112 samples of molluscs belonging to mussels (Mytilus chilensis, n = 47) and limpets (Nacella deaurata, n = 65), which were collected from the coastline of the Magellan Strait, Chile. Four (6.2%) samples of limpets exceeded the maximum limits for cadmium established in Europe. Limpets showed higher mean manganese, nickel and cadmium concentrations than mussels, whilst the mean selenium concentration in mussels was higher. The consumption of one serving (100 g) of molluscs represents a considerable contribution to the dietary daily intake of selenium, and limpets make a significant contribution to the manganese and cadmium intakes. The sampling zone influenced the trace element concentrations, and different uptakes were observed between the mollusc species.     

硒对镉胁迫下酿酒酵母抗氧化活性的影响

利用酿酒酵母（Saccharomyces cerevisiae）作为模式生物,主要通过测定硒对镉胁迫下酿酒酵母细胞内活性氧（reactive oxygen species,ROS）和丙二醛（malondialdehyde,MDA）含量,及重要抗氧化酶包括超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）、谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）和过氧化物酶（peroxidase,POD）抗氧化活性的变化,研究硒对镉胁迫下酿酒酵母的抗氧化活性的影响。结果表明：镉处理能极显著提高酿酒酵母细胞内ROS和MDA含量（P＜0.01）,进而对酿酒酵母细胞产生氧化胁迫,在培养体系内加入一定量的外源硒可极显著（P＜0.01）增加酿酒酵母细胞内抗氧化酶SOD、POD、CAT和GSH-Px活性,提高抗氧化物谷胱甘肽含量,加强酿酒酵母细胞对ROS和MDA的清除能力,这些结果表明外源硒的添加在酿酒酵母体内亦可对镉的影响产生拮抗作用,且与在动植物体内表现出一致的趋势,后续可以利用酿酒酵母作为模式生物进一步研究硒对镉毒性拮抗作用的一些机制。     

Effects of copper nanoparticles exposure in the mussel Mytilus galloprovincialis

CuO NPs are widely used in various industrial and commercial applications. However, little is known about their potential toxicity or fate in the environment. In this study the effects of copper nanoparticles were investigated in the gills of mussels Mytilus galloprovincialis, comparative to Cu(2+). Mussels were exposed to 10 μg Cu·L(-1) of CuO NPs and Cu(2+) for 15 days, and biomarkers of oxidative stress, metal exposure and neurotoxicity evaluated. Results show that mussels accumulated copper in gills and responded differently to CuO NPs and Cu(2+), suggesting distinct modes of action. CuO NPs induced oxidative stress in mussels by overwhelming gills antioxidant defense system, while for Cu(2+) enzymatic activities remained unchanged or increased. CuO NPs and Cu(2+) originated lipid peroxidation in mussels despite different antioxidant efficiency. Moreover, an induction of MT was detected throughout the exposure in mussels exposed to nano and ionic Cu, more evident in CuO NPs exposure. Neurotoxic effects reflected as AChE inhibition were only detected at the end of the exposure period for both forms of copper. In overall, these findings show that filter-feeding organisms are significant targets for nanoparticle exposure and need to be included when evaluating the overall toxicological impact of nanoparticles in the aquatic environment.     

基于高通量测序的紫贻贝中微生物群落分析

为探究不同状态下紫贻贝制品表面附着的微生物菌群组成情况。本实验以新鲜紫贻贝、冻藏紫贻贝、自制紫贻贝干,贮藏自制紫贻贝干和市售紫贻贝干为研究对象,通过对紫贻贝表面附着微生物提取及高通量测序分析,获得不同紫贻贝样品中微生物组成及变化情况。实验结果表明,各样本中有效序列范围为30066～40563条、Operational taxonomic unit(OTU)范围为28～128,其中市售紫贻贝干OTU数最低,而冻藏紫贻贝OTU数相对较高;新鲜紫贻贝和自制紫贻贝干中主要是嗜冷杆菌属和不动杆菌属,冻藏紫贻贝干中主要为嗜冷杆菌属,贮藏紫贻贝干中主要为假单胞菌属和嗜甲基菌属,而市售紫贻贝干中优势菌群为葡萄球菌属和肠球菌属。不同状态下的紫贻贝样品的菌群组成均存在着较大距离,表明紫贻贝状态、加工过程及贮藏销售环境等,均对贻贝产品菌群组成产生较大的影响。研究结果可为保障紫贻贝制品的质量与安全提供参考。     

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。     

Effects of mechanical handling,storage on ice and ascorbic acid treatment on lipid oxidation in cultured Newfoundland blue mussel (Mytilus edulis)

Lipid oxidation of cultured blue mussels (Mytilus edulis) during mechanical handling and storage on ice was investigated. Furthermore, the exposure of blue mussels to ascorbic acid (Asc) as an antioxidant and its effects on lipid oxidation of sample was monitored. Thiobarbituric acid reactive substances (TBARS) of stored mussels were significantly (p < 0.05) higher than those of the fresh mussels. Mechanical handling of mussels, which includes washing, sorting and packaging, for up to 1 h did not affect their oxidative status significantly (p < 0.05). Furthermore, exposing live mussels to specific concentrations of Asc retarded lipid oxidation significantly (p < 0.05) during storage on ice for only 5 days, after which the Asc became a pro-oxidant.     

Cooking makes cadmium contained in Chilean mussels less bioaccessible to humans

In Chile, upwellings occur periodically along the coasts, resuspending metals from the seafloor and reintroducing them to the food web. Chilean blue mussels, Mytilus chilensis, accumulate these toxic compounds and show high concentrations of cadmium. An in vitro simulated digestion method has been applied to specimens of M. chilensis previously contaminated with ¹⁰⁹Cd, to measure the bioaccessibility of cadmium for humans. The effects of the cooking process on the cadmium content of this species and on the resulting change in dietary bioaccessibility have also been evaluated. While cooking resulted in an increase in cadmium concentration in mussel flesh, cadmium remaining in the cooked flesh was also significantly less bioaccessible than cadmium occurring in the raw tissue. Estimations made in this study show that the intake of Cd from mussels by the Chilean population does not exceed the toxicological reference values established by the FAO/WHO; consequently, a health risk situation is not indicated.