Uptake and efflux of Cd and Zn by the green mussel Perna viridis after metal preexposure

Cadmium and zinc uptake from the dissolved phase, assimilation efficiency from the dietary phase, efflux rate constants, and body burden as well as clearance rate were measured in the green mussel Perna viridis with or without laboratory preexposure to Cd or Zn. Efflux rate constants and clearance rates were little affected by preexposure to either Cd or Zn. In contrast, the assimilation of Cd increased by 1.2-1.6 in mussels preexposed to Cd (subsequent Cd concentrations 10.2-25.9 microg(-1)) as compared to controls (0.19-0.39 microg g(-1)). This increase corresponded to an elevation in the proportion of Cd associated with the metallothionein-like proteins (MTLPs) in the mussels, suggesting that exposure to Cd and subsequent induction of MTLPs affected Cd accumulation. Exposure to Zn only resulted in elevated body concentrations following 7-d exposure to 250 microg L(-1), although Zn and Cd uptake from the dissolved phase were reduced by 24-47% by exposure to a lower concentration (100 microg L(-1)) for 7 and 21 d. Despite the lack of an increase in body Zn concentration, the subcellular distribution was altered such that the proportion of Zn associated with the metal-rich granules increased. This study indicates the importance of the subcellular distribution of metals in affecting the biokinetics and thus the toxic effects of metals on aquatic animals. Cd preexposure has potential effects on its influx from the dietary phase, e.g., increasing the importance of dietary uptake and further increasing the body burdens. In contrast, preexposure to Zn has a negative effect on Cd and Zn influx from the dissolved phase, suggesting the mechanism of Zn regulation but also potentially reducing Cd uptake and body concentrations over the long-term exposure. Such effects may have implications for biomonitoring studies involving a single species that modifies physiological processes affecting metal uptake (and hence bioavailability). Caution is needed in extrapolating data to species not capable of making such changes, particularly for Cd, which is not regulated and for which the effects of an elevated body burden are most obvious.     

Some physico-chemical,functional and rheological properties of actomyosin from green mussel (Perna viridis)

The physico-chemical and rheological properties of fresh actomyosin from green mussel (Perna viridis) have been evaluated. Amino acid profile of actomyosin revealed a relatively high proportion of glutamic acid, alanine, tryptophan and aspartic acid. Ultraviolet absorption spectra of actomyosin solution showed a maximum absorbance in the wavelength region of 270–280 nm indicating presence of aromatic amino acid residues. Dynamic viscoelastic behavior of actomyosin revealed the ability to form network during heating, however, the strength of network appeared to be weak as given by frequency sweep of the heat set gel. The flow behavior of actomyosin solution indicated pseudoplastic behavior at different concentrations and temperatures. Casson and Herschel-Bulkley models were used to evaluate flow behavior of actomyosin and revealed maximum yield stress value at 30 mg/ml at 40 °C.     

Heat shocking of Philippine green mussels, Perna viridis

The use of different methods of heat shocking for green mussels was evaluated. These methods were heat treatment at 60 and 100 °C either in a hot water bath, in water‐saturated air or in dry heat. It was established that relaxation of the adductor muscles, which facilitates shucking, was quickest for the hot water bath treatment at both test temperatures. This treatment caused 100% of the mussels to be open at either 60 or 100 °C in 3–5 and 0.33–1 min exposure times respectively. The sensory acceptability of all the heat‐shocked mussel meats ranged from dislike slightly to like slightly. Generally, the increase in pH and water activity of the heat‐treated mussels, relative to the untreated mussels, was not statistically significant at the 5% level of significance.     

Uptake of aqueous and dietary metals by mussel Perna viridis with different Cd exposure histories

The influences of different Cd pre-exposure regimes (route, concentration, and duration of Cd exposure) on the bioavailability of Cd, Ag, Hg, and Zn to the green mussels Perna viridis were quantified in this study. Following pre-exposing the mussels to Cd, we measured the mussel's tissue Cd concentration and clearance rate, as well as the metal dietary assimilation efficiency (AE) and the influx rate from the dissolved phase of the four studied metals. Differences in the route (aqueous and dietary pathways) and the history of pre-exposure (combined Cd concentration and duration) did not significantly affect the subsequent Cd dietary and aqueous uptake. The Cd dietary AEs increased following both the dissolved and dietary Cd pre-exposure. There was a significant correlation between the Cd AE and the accumulated Cd body concentration in the mussels. Dietary assimilation of Hg and Zn also increased slightly (but not significantly) after Cd pre-exposure, but the AEs of Ag remained constant. Except for the significant decrease in the dissolved uptake of Hg, Cd pre-exposure did not apparently affect the uptake of the other three metals from the solution. Metal-metal interactions are likely to be affected by the specificity of metallothionein induction. Our study demonstrated that the Cd body concentration as well as the environmental Cd concentration instead of the history of pre-exposure was more important in affecting the Cd accumulation in the mussels. Such factors need to be considered in interpreting metal body concentrations in biomonitors.     

Physico‐chemical and functional properties of proteins from green mussel (Perna viridis) during ice storage

The effect of ice storage on the properties of proteins from green mussel (Perna viridis) has been investigated. Ice storage of green mussel for a period of 19 days revealed a marginal increase in moisture and decrease in total nitrogen content. There was significant reduction (P < 0.05) in non‐protein nitrogen content and calcium activated adenosine triphosphatase enzyme activity. The solubility of the total proteins in high ionic strength buffer decreased marginally. The ice storage of green mussel had a significant effect on association‐dissociation/denaturation phenomenon of proteins as revealed by gel filtration profile, reduced viscosity values and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) pattern. The dynamic viscoelastic behaviour of green mussel meat in the temperature range of 30–90 °C revealed higher storage modulus (G′) values at a later part of ice storage. The emulsion capacity of green mussel did not show significant variation (P < 0.05) during ice storage. Copyright © 2006 Society of Chemical Industry     

Effect of turmeric and lemongrass essential oils and their mixture on quality changes of refrigerated green mussel (Perna viridis)

Effect of turmeric and lemongrass essential oils (Eos) and their mixture on quality of green mussel stored at 4 °C was investigated. The mixture of 0.25% turmeric and 0.25% lemongrass Eos could lower microbiological and chemical deterioration of mussel as evidenced by the lower microbial counts, total volatile base, ammonia, trichloroacetic acid‐soluble peptide contents and thiobarbituric acid‐reactive substances, compared with the control (P < 0.05). It indicated that a mixture of turmeric and lemongrass Eos in mussel showed synergistic effect on the retardation of bacterial growth and lipid oxidation. However, samples treated with 0.5% lemongrass oil exhibited the higher likeness score for odour and flavour, compared with the samples treated with other Eos throughout the storage of 15 days. Samples treated with turmeric essential oil caused the changes in odour and flavour. Therefore, lemongrass treatment was shown to be the promising means to prevent the deterioration and maintain the odour and flavour attributes of mussel during prolonged refrigerated storage.     

翡翠贻贝粗多糖降血脂作用的研究

目的：研究翡翠贻贝粗多糖(PCP)对高脂血症小鼠的降血脂作用及其机制。方法：取雄性昆明小鼠72只,每组12只。随机分正常对照组(灌饲生理盐水)、模型对照组(灌饲生理盐水)、阳性对照组(灌饲辛伐他汀5mg/kg) 、翡翠贻贝粗多糖低剂量组(50mg/(kg·d))、中剂量组(100mg/(kg·d))、高剂量组(200mg/(kg·d))。正常对照组小鼠从实验开始至结束用普通饲料喂养,其他5组小鼠均喂高脂饲料。30d后测定小鼠血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)和一氧化氮(NO)含量,肝脏TC、TG含量,血清卵磷脂胆固醇酰基转移酶(LCAT)以及血清和肝脏脂蛋白脂酶(LPL)、肝脂酶(HL)活性。结果：翡翠贻贝粗多糖能明显降低模型小鼠血清TC、TG、LDL-C含量和动脉粥样硬化指数(AI)(P＜0.01),显著降低肝脏TC含量(P＜0.01)、TG含量(P＜0.01),提高血清HDL-C含量和NO含量(P＜0.01),提高血清LCAT、血清和肝脏HPL、HL活性(P＜0.01)。结论：翡翠贻贝粗多糖对小鼠有显著的降血脂效应,该作用可能与翡翠贻贝粗多糖能明显增强LCAT、LPL、HL酶活性,提高HDL-C、NO水平有关。     

翡翠贻贝糖胺聚糖的体外抗氧化活性研究

本试验研究了翡翠贻贝糖胺聚糖的体外抗氧化作用.采用体外试验研究其对羟自由基、DPPH 自由基、超氧阴离子的清除作用以及小鼠肝匀浆脂质过氧化的保护作用.结果表明,翡翠贻贝糖胺聚糖体外可清除O<'2->、OH、DPPH;对小鼠肝脏自发脂质过氧化具有较好的抑制作用,因此,翡翠贻贝糖胺聚糖体外具有很好的抗氧化活性.     

响应面法优化翡翠贻贝糖胺聚糖提取工艺的研究

以湛江地区产量丰富的翡翠贻贝全脏器为原料,通过胰酶和枯草杆菌中性蛋白酶双酶水解、醇沉后得到翡翠贻贝糖胺聚糖粗品。使用二次回归正交旋转组合设计研究液料比、加酶量、酶解时间3个因素对糖胺聚糖粗品得率与糖胺聚糖含量乘积的影响,从而确定翡翠贻贝糖胺聚糖提取的最佳工艺条件。经响应面分析,回归模型具有较高的拟合度。结果显示,最佳提取工艺条件为液料比2.30:1,加酶量0.94%,酶解时间3.46h,在此条件下,重复实验结果与响应面法优化提取翡翠贻贝糖胺聚糖的模型预测值25.50(×10-4)之间的标准误差为1.10%,低于5%。     

翡翠贻贝副肌球蛋白的特性及在模拟胃肠液中的消化

为探究贝类副肌球蛋白（paramyosin,PM）的热稳定性、pH值稳定性及其在模拟胃肠液中的消化特性,以翡翠贻贝（Perna viridis）为对象,利用硫酸铵盐析和羟基磷灰石柱层析等方法,从肌肉中纯化PM,采用肽质量指纹图谱法对其进行鉴定,利用圆二色谱测定其二级结构及热变性温度。结果显示,翡翠贻贝PM分子质量为99.5 kDa;肽质量指纹图谱分析获得26 个肽段,共330 个氨基酸残基,与地中海贻贝(Mytilus galloprovincialis)PM的序列一致性达到100%,表明纯化的蛋白为PM。圆二色谱结果显示,PM呈现典型的α-螺旋结构,其热变性温度为（56.3±0.2）℃。在30～100 ℃热处理30 min,PM未出现沉淀聚集现象,在pH 6～11范围内也较稳定,但当pH≤5时稳定性差,出现沉淀聚集现象。与胃蛋白酶、胰蛋白酶及胰凝乳蛋白酶对PM的单独消化作用相比,3 种酶连续作用可使PM有效降解,但仍有分子质量30 kDa的片段未被完全消化。本研究表明,翡翠贻贝PM具有较好的耐热性及耐消化性,为贻贝深加工及PM的后续研究提供一定理论参考。     

Effects of aqueous and dietary preexposure and resulting body burden on silver biokinetics in the green mussel Perma viridis

To determine whether preexposure of green mussel Perna viridis to Ag influenced metal uptake kinetics we compared various physiological indicators of metal uptake kinetics between the control mussels and mussels preexposed to Ag in both diet and water at different levels (up to 5 weeks). In all preexposed mussels, the assimilation of Ag increased by 1.1-3.0 times with increasing Ag body concentration (0.651-19.3 microg g(-1)) as compared with the controls (Ag body concentration of 0.311-0.479 microg g(-1)), whereas the efflux rate constants decreased by 45-88%. There was no significant increase in Ag associated with the metallothionein-like protein (MTLP) fraction following exposure of the mussels to Ag through either the dissolved or food phase. The clearance rates were little affected or depressed byAg preexposure, and the relationship between the Ag influx rate from the dissolved phase and the Ag preexposure was somewhat complicated. The influx rate decreased with increasing Ag body burden at <2.5 microg g(-1), above which it increased with increasing Ag body burden. Our results indicate that the mussels may modify physiological processes to ambient chronic Ag exposure, consequently accumulating more Ag. Ag body concentration in these mussels may therefore increase disproportionally in response to increasing Ag concentration in the ambient environments. Ag preexposure and resulting body burden should be considered carefully when interpreting the observed Ag concentration in biomonitoring animals to evaluate the Ag pollution in seawater.     

翡翠贻贝不同醇沉物体外抗氧化活性研究

通过采用不同体积分数的乙醇进行分级沉淀翡翠贻贝提取物,获得3个不同醇沉物ME45、ME60和ME80,并比较其对清除DPPH自由基、超氧阴离子自由基(·O_2~-)、羟自由基(·OH)、总抗氧化能力及抑制肝组织自发性脂质过氧化作用(LPO)的效果。结果表明:翡翠贻贝不同醇沉物ME80、ME60和ME45均具有抗氧化活性,呈显著的量效关系,其抗氧化能力因反应体系的不同而不同。在总抗氧化、·O_2~-、LPO测定体系中,越高浓度乙醇沉淀物的抗氧化活性越强,ME80ME60ME45;在DPPH自由基清除体系中,抗氧化活性次序为ME60ME80ME45;而在·OH清除体系中,抗氧化活性次序为ME45ME80ME60。总体而言,ME80抗氧化能力优于ME60和ME45,是一种潜在的天然抗氧化剂的良好来源,具有进一步开发应用前景。     

翡翠贻贝多糖的分离及其对高脂饮食小鼠抗氧化活性的影响

已有的研究表明：翡翠贻贝粗多糖（PVP）对高脂模型小鼠具有显著的降低血脂作用,本文对翡翠贻贝粗多糖进行了纯化与分析,并研究了其对高脂模型小鼠体内抗氧化作用的影响。PVP经DEAE-52与Sephadex柱层析分离得到两个主要级分P1和P2。经化学分析,P1和P2均为有硫酸基的酸性多糖,相对分子质量分别为6.89×105 Da和2.87×105 Da。氨基葡萄糖：糖醛酸：氨基半乳糖的百分比例分别为：3.7:2.6:1、2.8:1.6:1。以翡翠贻贝粗多糖低[50mg/(kg?d)]、中[100mg/(kg?d)]、高[200mg/(kg?d)]剂量灌喂高脂饮食小鼠（日常饮食中添加2%胆固醇）。结果显示：PVP中、高剂量组能显著增强高脂模型小鼠血清、肝脏和大脑中的T-AOC、GSH-Px, SOD 和CAT活性,且降低MDA含量(p﹤0.05或p <0.01)。研究表明PVP可能通过激活高脂小鼠体内抗氧化酶活性、降低体内过氧化水平而起到降低血脂作用。     

翡翠贻贝提取物对小鼠急性肝损伤的保护作用

本文研究探讨了翡翠贻贝提取物对小鼠急性肝损伤的保护作用。建立四氯化碳(CCl4)致小鼠急性肝损伤模型,测定血清天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)含量及肝组织丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、肿瘤坏死因子α(TNF-α)和白介素-6(IL-6)含量;采用双向电泳分析肝脏差异表达蛋白;病理切片观察小鼠肝组织病理损伤的情况。结果表明,与模型组相比较,翡翠贻贝提取物各剂量组小鼠ALT、AST水平和MDA含量均显著降低,SOD、CAT、GSH-Px和GSH含量显著提高,TNF-α和IL-6水平也显著降低(p0.01)。通过双向电泳获得了蛋白质显著差异点97个,鉴定出在模型组中有4个蛋白高表达,1个蛋白低表达;在翡翠贻贝提取物组中3个蛋白高表达。病理镜检显示小鼠肝脏损伤程度有所减轻。从以上实验结果可推测,翡翠贻贝提取物对CCl4引起的小鼠急性化学性肝损伤具有明显的保护作用。     

翡翠贻贝糖胺聚糖体外抑制ONE-2Z肿瘤细胞生长作用的研究

以南海贝类翡翠贻贝全脏器为原料提职得到糖胺聚糖粗品,经蛋白质等电点沉淀法处理后得到糖胺聚糖精制品(RG),糖胺聚糖含量52.3%.应用MTT法检测糖胺聚糖精制品对人鼻咽癌细胞CNE-2Z体外抗肿瘤活性.结果显示:RG不同剂量在作用不同时间后的抑瘤效果不同,其中200μg/mnL的RG作用 72h抑瘤率达到最高值为29.3%.RG与5-Fu合用的抑瘤效果,随着药物作用时间的延长,两者由协同作用变为单纯相加作用.     

Antioxidant and antithrombotic effects of green mussels (Perna canaliculus) in rats

In the past decade, the use of marine mussels as seafood is being more popular. They considered being a rich source of various nutritional bioactive compounds that aroused the scientific community's interest. This study investigated the antioxidant and the antithrombotic consequences on Sprague-Dawley male rats after adding dried New Zealand mussel Perna canaliculus in their diet. The biochemical, hematological and histopathological changes were also observed. Forty rats were divided into four groups according to the amount of dried mussels in their diet, in addition to a control group that consumed a basal diet only. Group 1 consumed 25% dried mussels in its basal diet; Group 2 consumed 35% dried mussels in its basal diet, and Group 3 was consumed 45% dried mussels in its basal diet. The biochemical parameters showed improvements in liver function. Interestingly, the lipid profile decreased, especially the low-density lipoprotein cholesterol (LDL-C) levels which were reduced significantly in Group 3 (p < .01). These observations were accompanied by a decrease in iron levels significantly as the amount of dried mussels increased (p < .01). Furthermore, the noticed changes in the hematological profile prove that there is an increase in antithrombotic activity. Dried mussels had potent antioxidant effects in the liver as shown by increased lipid peroxide (p < .05), reduced glutathione (p < .05), and glutathione peroxidase (GSH-Px; p < .05). Additionally, antioxidant activity in the kidney was shown to increase through GSH-Px activity (p < .01). In conclusion, these results indicate that consuming dried mussels resulted in improved biochemical and antioxidants activities and could be used as an antithrombotic agent.     

Prevalence and biofilm-forming ability of Listeria monocytogenes in New Zealand mussel (Perna canaliculus) processing plants

Greenshell™ mussels are New Zealand’s largest seafood export species. Some export markets require compliance with ‘zero’ tolerance legislation for Listeria monocytogenes in 25 g of product. Even though individually quick frozen (IQF) mussel products are labeled ‘to be cooked’, and are not classified as ready-to-eat, some markets still require them to comply with the strict policy. Three mussel processing plants were assessed for the pattern of L. monocytogenes contamination on raw material, environment, food contact surfaces, and in the final product. Cultures (n = 101) obtained from an industrial Listeria monitoring program from August 2007 to June 2009 were characterized by serotyping and pulsed field gel electrophoresis. Using the crystal violet method, isolates were assessed for their ability to form biofilms. This work confirmed the presence of L. monocytogenes in raw and processed product, and the importance of cross-contamination from external and internal environments. Processing plants had L. monocytogenes pulsotypes that were detected more than once over 6 months. No correlation was found between biofilm-forming ability and persistent isolates. Two pulsotypes (including a persistent one), were previously isolated in human cases of listeriosis in New Zealand, but none of the pulsotypes matched those involved in international outbreaks.     

野苋菜植物修复皮革工业铬污染土壤的研究

为选择超积累重金属和对气候具有耐性的植物,以达到利用植物修复重金属污染土壤的目的。采用田间种植,比较了超积累重金属植物大叶红苋菜(298)与野苋菜、向日葵、玉米等4种植物修复铬污染。根茎叶经晒干灼烧,回收铬处理,而实现无二次污染修复土壤。研究结果表明:这些植物的根茎叶对皮革工业铬污染具有较强的吸收和积累能力,野苋菜的地上部生物量分别是向日葵的1.5倍、玉米的1.2倍、大叶红苋菜(298)的1.05倍。对于地下部生物量而言,4种植物的高低顺序依次为野苋菜>大叶红苋菜(298)>玉米>向日葵。4种植物的根茎叶对铬累积量的高低顺序依次为野苋菜>大叶红苋菜(298)>向日葵>玉米。野苋菜能吸收富集铬重金属并且具有耐铬重金属的特性,基于其具有生物量较大、生长速度快、耐高温、耐干旱的特点,作为重金属污染的修复植物具有较好的应用前景。