Immune inhibition in marine mussels by polycyclic aromatic hydrocarbons

Polycyclic aromatic pollutants produced by a range of industrial processes and the combustion of fossil fuels. They eventually enter the marine environment, and are bioaccumulated in the tissues of sessile, filter-feeding bivalves, causing a variety of sublethal effects. Few studies, however, have examined immune inhibition in molluscs by these xenobiotics. Here, the immunotoxic effects of PAHs were investigated in marine mussels (Mytilus edulis) by means of in vivo exposure experiments. Animals were exposed to a PAH cocktail of anthracene, fluoranthene and phenanthrene for 2 or 4 weeks. The haemolymph was then extracted, and phagocytosis and lysosomal neutral red retention assays performed to examine the effects of PAHs on particle uptake by haemocytes and lysosome integrity, respectively. PAHs were found to inhibit phagocytosis and damage lysosomes. It is hypothesized that PAHs exert their toxicity directly on the lysosomes. A possible consequence of such lysosomal damage will be immune impairment in mussels leading to reduced resistance to infectious diseases.     

Pathological reactions and recovery of hepatopancreatic digestive cells from the marine snail Littorina littorea following exposure to a polycyclic aromatic hydrocarbon

The aim of this study was to investigate the cellular pathological responses of hepatopancreatic digestive cells from the periwinkle Littorina littorea exposed to the polycyclic aromatic hydrocarbon (PAH) fluoranthene and to ascertain whether any injurious effects were reversible within the experimental time scale. A secondary objective was to establish the relationship of the various reactions to animal health status, using lysosomal stability as an index of well-being. Exposure of snails to a concentration of 335 microgl(-1) (1.7 microM) fluoranthene (seawater renewed and spiked daily with fluoranthene) for 5 days resulted in a reduction in lysosomal stability (neutral red retention) and endocytosis; and an increase in smooth endoplasmic reticulum (ER) and 7-ethoxycoumarin-o-deethylase (ECOD; measured as cyano-ECOD) activity measured in isolated live digestive cells. Exposed snails treated with clean seawater for a further 8 days resulted in a return to control levels of lysosomal stability, ECOD and ER; endocytosis showed only a partial recovery. Multi-variate and uni-variate analysis showed that there were strong correlations between the various cellular biomarker responses. These findings are interpretable within the current framework of molluscan biomarker responses to PAHs. Principal component analysis was used to derive the first principal component for endocytosis, ER and ECOD reactions and these were plotted against lysosomal stability as a measure of cellular well-being. The resulting significant regression represents the mapping of the individual biomarkers within health status space for a gradient of fluoranthene toxicity. From this analysis, we concluded that endocytosis is an indicator of healthy snails while proliferation of ER and to a lesser extent induced ECOD are indicative of dysfunction and reduced health. Finally, the results indicate that stress induced by chronic exposure to a PAH is reversible.     

Interactions among metals in the spectrochemical determination of trace amounts of cadmium in marine mussels

The determination of trace amounts of inorganic elements by electrothermal atomic absorption spectrophotometry (ETA-AAS) or inductively coupled plasma atomic emission spectrometry (ICP-AES) suffers from some kinds of interference due to the inorganic fraction of the matrix of many environmental samples. The ratio between a major matrix element and the analyzed trace element plays an important role in the spectrochemical behaviour of the latter. The resulting enhancing or depressing effect also gives rise to severe faults when the well known standard addition method (SAM) is used. The present work shows the interactions due to the presence of elements such as calcium, sodium, potassium, magnesium and iron during the spectrochemical determinations of trace amounts of cadmium in marine mussels. A possible liquid anion exchange extraction is suggested for the analysis of cadmium by ETA-AAS.     

Tolerance of five species of tropical marine mussels to continuous chlorination

The paper examines the relative lethal and sublethal response of five important tropical marine mussels (Perna viridis, Perna perna, Brachidontes striatulus, Brachidontes variabilis and Modiolus philippinarum) to different chlorine concentrations varying from 0.25 to 15 mg l(-1). The mussels were observed to co-exist in the cooling water circuits of a coastal power station that adopted intermittent chlorination as a fouling control technique. The five mussel species showed, in response to chlorination, 100% mortality at significantly different exposure times, indicating significant species-specific variability in chlorine tolerance. For example, at 1 mg l(-1) residual chlorine, B. variabilis and P. viridis took 288 and 816 h, respectively, to achieve 100% mortality. The time taken for 100% mortality decreased with increasing chlorine residual concentration. The effect of mussel size (= mussel age) of P. viridis, P. perna, B. striatulus and M. philippinarum on mortality was significant between 1 and 5 mg l(-1) residual chlorine, with larger mussels showing greater resistance than smaller ones. All mussel species showed progressive reduction in physiological activities when chlorine residuals were increased from 0 to 1 mg l(-1). However, species-specific differences in the relative rate of physiological activities were observed. Accordingly, relative reduction in physiological activities in response to chlorination was the lowest in P. viridis and the highest in B. variabilis. The data clearly indicate significant differences in the lethal and sublethal responses of the five mussel species to chlorination. The results, therefore, suggest that for effective fouling control, chlorine treatment against mussels has to be employed judiciously, depending on the mussel species involved.     

Enteroviruses in mussels and marine sediments and depuration of naturally accumulated viruses by green lipped mussels (Perna canaliculus)

Surveys were carried out over 16 months to assess the distribution of enteroviruses of human origin in sediments and mussels near two sewage outfalls on the North Taranaki Coast, New Zealand. Enteroviruses were present in high numbers in both sediments and shellfish near the New Plymouth sewage outfall with maximum virus levels of 32 000 pfu 100 g^‐1 of wet mussel tissue and 59 pfu 100 g^‐1 of wet sediment material. Viruses were recovered occasionally from sediments and mussels near the Waitara Borough outfall. Coxsackievirus B4 was the predominant virus type isolated but CB5 and Poliovirus types 1, 2, and 3 were also recovered. Attempts to depurate virus‐contaminated New Plymouth mussels, by keeping them in water for 8 days with daily water replacement, did not achieve a significant reduction in virus numbers.     

Sewage-derived bacteria monitored in a marine water column by means of captive mussels

Batches of mussels, Mytilus edulis, obtained from a sewage-free shore were introduced into the water column at a sewage polluted site and the changed content (Escherichia coli, faecal streptococci) was assessed after immersion periods of 2 to 40 h. Rapid bacterial uptake was demonstrated; changes were analysed with respect to immersion period, revealing that 2h was satisfactory. The numbers of bacteria varied with height in the water column; mussels from the sea bed contained higher numbers of E. coli than mussels immersed just below the surface except for mussels withdrawn at, and for about 3h after, low water (LW). These observations were shown to be related to the characteristics of the e effluent and tidal systems operative at the site.     

Significance of metallothioneins and lysosomes in cadmium toxicity and homeostasis in the digestive gland cells of mussels exposed to the metal in presence or absence of phenanthrene

Metallothioneins and lysosomes are known to be involved in cellular detoxication and sequestration of certain metals^1–3 and both have been identified in this role in elimination of copper from marine mussels (Mytilus edulis/galloprovincialis).³ Cadmium (Cd), however, has been shown to persist in the cells of the digestive gland for long periods with only minimal elimination. An experiment was designed to test the effects of Cd on the fragility of lysosomal membranes in the digestive cells as a measure of cellular injury,^4,5 metallothionein content of the digestive gland and cadmium concentration in this organ. Phenanthrene was used also to destabilise lysosomal membranes⁶ in order to test if increased lysosomal fragility interfered with cadmium metabolism and detoxication. The results demonstrated that Cd induced metallothionein synthesis and that elimination of Cd was minimal after 28 days in clear seawater. Lysosomal fragility was initially increased but this effect was soon reversed, even with continued exposure to Cd. The lysosomal destabiliser, phenanthrene, did not appear to affect accumulation of Cd or levels of metallothionein.     

贻贝抗菌肽的研究进展

抗菌肽是一类广泛存在于整个生物界中的双亲性小分子碱性多肽,是生物体固有免疫的关键因子之一.自Steiner等在天蚕(Hyaophora cecropia)中发现世界上第一个抗菌肽-天蚕素(Cecropin)后,到目前为止,在各种生物中总共发现了1 200多种抗菌肽.     

Hydrographic surveying in the EEZ: differences and overlaps with marine scientific research

This paper reviews differences and overlaps between hydrographic surveying and marine scientific research in the exclusive economic zone (EEZ), including the concept of military surveying. It concludes that recent trends with technology, the utility of hydrographic data and State practice suggest that hydrographic surveying in the EEZ should be under the jurisdiction of the coastal State. Paradoxically arguments for military surveys in the EEZ being outside coastal State jurisdiction appear stronger than those for hydrographic surveying. The paper offers some guidelines related to the conduct of hydrographic surveying in the EEZ.     

A severity index to assess and monitor the incidence of pollution-related pathological conditions in marine organisms

A normalised matrix of the occurrences and co-occurrences of n-pathological conditions in a hypothetical population is termed a severity matrix and was used to define a volume in an n-dimensional vector space representing the severity or extent of the spread of the conditions in the population. The changes in this volume resulting from varying the numbers of occurrences and co-occurrences in the severity matrix are described by the varying determinant of the matrix. The natural logarithm of this determinant was shown to be a consistent measure or index of severity for comparing the spread of the same pathological conditions among different populations or among chronological samples from the same population. While the eigenvalues of the severity matrix are used to determine the relative contribution of each pathological condition to the index of severity, the eigenvectors serve to investigate possible associations among the conditions. Actual data from a population of the soft-shell clam Mya arenaria were used to demonstrate the application of this methodology to characterise the incidence of five pathological conditions assumed to be indicators of pollution related stress on the clam population.     

A comparison of biological trends from four marine ecosystems: Synchronies, differences, and commonalities

Major features of four marine ecosystems were analyzed based on a broad range of fisheries-associated datasets and a suite of oceanographic surveys. The ecosystems analyzed included the Gulf of Maine/Georges Bank in the Northwest Atlantic Ocean, the Norwegian/Barents Seas in the Northeast Atlantic Ocean, and the eastern Bering Sea and the Gulf of Alaska in the Northeast Pacific Ocean. We examined survey trends in major fish abundances, total system fish biomass, and zooplankton biomasses. We standardized each time series and examined trends and anomalies over time, using both time series and cross-correlational statistical methods. We compared dynamics of functionally analogous species from each of these four ecosystems. Major commonalities among ecosystems included a relatively stable amount of total fish biomass and the importance of large calanoid copepods, small pelagic fishes and gadids. Some of the changes in these components were synchronous across ecosystems. Major differences between ecosystems included gradients in the magnitude of total fish biomass, commercial fish biomass, and the timing of major detected events. This work demonstrates the value of comparative analysis across a wide range of marine ecosystems, suggestive of very few but none-the-less detectable common features across all northern hemisphere ocean systems.     

南海冷泉区贻贝(Bathymodiolus platifrons)附生菌的分离培养与多样性分析

以采集后适应培养0~24 h以及添加甲烷和硫化钠培养24~240 h的南海冷泉区深海贻贝(Bathymodiolus platifrons)为材料,取其鳃部,分析附生菌的多样性与适应性变化状况。共分离鉴定出贻贝附生菌270株,对菌株的16S r DNA进行聚类分析,结果表明所分离菌株主要分布在4个门,21个属,其中变形菌的数量最多且多样性高。分析发现原位新采集的贻贝鳃部附生菌的多样性较高,6 h后附生菌的多样性明显降低。分别添加甲烷和硫化钠对深海贻贝进行培养,甲烷组与碳代谢有关的假单胞菌的数量逐渐增多,且在甲烷组240 h中发现2株食烷菌属菌株。硫化钠组的芽孢杆菌属所占比例升高。此外还发现4株潜在的新种。本研究实现了深海冷泉区贻贝的实验室培养,并对贻贝鳃部附生菌群结构进行了分析,丰富了海洋极端环境微生物资源库,并为深入解析贻贝与其附生菌之间的相互作用关系奠定了基础。     

A computational model of the digestive gland epithelial cell of marine mussels and its simulated responses to oil-derived aromatic hydrocarbons

This paper describes a computational model of digestive gland epithelial cells (digestive cells) of marine mussels. These cells are the major environmental interface for uptake of contaminants, particularly those associated with natural particulates that are filtered from seawater by mussels. Digestive cells show well characterised reactions to exposure to lipophilic xenobiotics, such as oil-derived aromatic hydrocarbons (AHs), which accumulate in these cells with minimal biotransformation. The simulation model is based on processes associated with the flux of carbon through the cell. Physiological parameters such as fluctuating food concentration, cell volume, respiration, secretion/excretion, storage of glycogen and lipid, protein/organelle turnover (autophagy/resynthesis) and export of carbon to other tissues of the mussel are all included in the model. The major response to AHs is induction of increased autophagy in these cells. Simulations indicate that the reactions to AHs and food deprivation correspond well with responses measured in vivo.     

Histopathology of mussels (Mytilus sp.) from the Tamar estuary, UK

This study assessed numerous histological parameters as markers of health status in mussels (Mytilus spp.) collected from several locations along a contamination gradient on the River Tamar and two coastal sites on the north and south coast of Cornwall, UK. Twenty-seven health parameters were assessed including the presence of pathogens, inflammatory lesions, non-specific pathologies and reproductive condition. Logistic regression showed that reproductive condition and inflammatory lesions showed changes indicative of a contamination gradient response. Mussel populations further upstream within the Tamar were relatively less developed compared to mussels situated downstream in the estuary. Compared to coastal locations, mussels sampled within the Tamar also exhibited a higher prevalence of inflammatory lesions that increased at locations situated furthest upstream. Similarly, levels of lipofuscin within the kidney epithelium were highest in mussels sampled within the estuary and Whitsand Bay compared to Trebarwith Strand. The most prevalent pathogens observed during this survey included Rickettsia/Chlamydia-like organisms (R/CLO), gill ciliates including Ancistrum mytili, the copepod Mytilicola intestinalis, Ciliophora-like organisms and Marteilia sp. Marteilia sp. was observed in 31% of the mussels sampled from the Cremyll Ferry site. Generally, the range and prevalence of pathogens was highest from the two estuarine locations at Cremyll Ferry and Wilcove. No significant differences were observed between estuarine sampling sites and Whitsand Bay with respect to median epithelial cell height of digestive tubules, however mussels from Trebarwith Strand did exhibit a reduced median epithelial cell height compared to mussels sampled from other sampling sites. Species genotyping was also undertaken during this study in order to consider any histological differences in relation to species. Results are discussed in relation to histopathology health parameters and biological effects monitoring.     

Recent trends in organochlorine residues in mussels (Mytilus edulis) from the Mersey Estuary.

Blue mussels (Mytilus edulis) taken from several sites in the Mersey Estuary, an urban-industrial water body in NW England, have been analyzed for residues of the persistent organochlorines, DDT, PCB congeners nos. 28, 52, 101, 118, 138, 153 and 180 (ICES7), and alpha-MHCH (alpha-methyl hexachlorocyclohexane). The concentration range for sigmaPCB (ICES7) was 13.9-34.9 microg kg(-1) in 1994 compared with 9.6-31.9 microg kg(-1) in 1998, whilst the equivalent concentrations of sigmaDDT were 8.9-32.4 microg kg(-1) and 4.5-16.8 microg kg(-1), respectively. The concentration of alpha-MHCH, an organochlorine largely restricted to the Mersey Estuary, was 1.2-11 microg kg(-1) in 1994 and 0.3-1.3 microg kg(-1) in 1998. At both sampling dates the inner estuary sites of Rock Ferry and Egremont were more contaminated than the outer estuary sites of New Brighton. Dove Point and Caldy Blacks. The lower concentrations of organochlorines in mussels in 1998 compared with 1994 are thought to be early evidence of significant improvements in water quality derived from major capital investment in the treatment of industrial effluents and sewage wastewater, linked to a combination of stricter legislative controls and the environmental benefits from the adoption of new, clean technologies in manufacturing.     

DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis during anoxic stress and aerobic recovery

Anoxia-induced DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis was assessed with the alkaline comet assay (single-cell gel electrophoresis). The alkaline comet assay method for detecting DNA strand breaks and alkali labile sites in individual cells. DNA damage was determened in the scallops (M. yessoensis) gill cells. The scallops were exposed to air for 8 h showing a clear increase in the levels of DNA damage. After the air exposure, M. yessoensis were re-submersed for a period of 12 h, leading values to return to a pre-aerial exposure level. Control animals were kept immersed during the whole period. The resulting data demonstrate that natural influences, such as oxygen depletion (anoxia) in seawater, can be responsible for the induction of DNA damage. If the scallops were re-immersed in oxic conditions, the anoxically induced breaks were repaired. The main mechanisms influencing the integrity of the DNA structure are discussed in this paper.     

Connectivity clues from short-term variability in settlement and geochemical tags of mytilid mussels

The use of geochemical tags in calcified structures of fish and invertebrates is an exciting tool for investigating larval population connectivity. Tag evaluation over relatively short intervals (weeks) may detect environmental and ecological variability at a temporal scale highly relevant to larval transport and settlement. We collected newly settled mussels (Mytilus californianus and M. galloprovincialis) weekly during winter/spring of 2002 along the coast of San Diego, CA, USA, at sites on the exposed coast (SIO) and in a protected coastal bay (HI), to investigate temporal patterns of geochemical tags in mussel shells. Analyses of post-settlement shell via LA-ICP-MS revealed statistically significant temporal variability for all elements we examined (Mg, Mn, Cu, Sr, Cd, Ba, Pb and U). Despite this, our ability to distinguish multielemental signatures between sites was largely conserved. Throughout our 13-week study, SIO and HI mussels could be chemically distinguished from one another in 78–87% of all cases. Settlement varied between 2 and 27 settlers gram-byssus^?1 week^?1 at SIO and HI, and both sites were characterized by 2–3 weeks with “high” settlement. Geochemical tags recorded in early larval shell of newly settled mussels differed between “high” and “low” settlement weeks at both sites (MANOVA), driven by Mg and Sr at SIO (p = 0.013) and Sr, Cd, Ba and Pb at HI (p < 0.001). These data imply that shifts in larval sources or transport corridors were responsible for observed settlement variation, rather than increased larval production. In particular, increased settlement at HI was observed concurrent with the appearance of geochemical tags (e.g., elevated Cd), suggesting that those larvae were retained in upwelled water near the mouth of the bay. Such shifts may reflect short-term changes in connectivity among sites due to altered transport corridors, and influence the demography of local populations.     

Heavy metals in mussels (Mytilus galloprovincialis) from the gulf of la spezia and from the promontory of Portofino,Italy

In different samples of Mytilus galloprovincialis Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn were determined by AAS. The mussels were taken from 11 sites in the Port of La Spezia. Typical concentration ranges (μ/g dry weight) were as follows: Cd, 2.0–6.8; Co, 0.8–3.2; Cr, 5.8–19.5; Cu, 6.9–33.7; Hg, 0.15–0.38; Mn, 11.8–37.8; Ni, 1.3–10.9; Pb, 13.9–44.6 and Zn, 203–379.Other samples were collected at 4 sites on the Promontory of Portofino and the following values were obtained: Cd, 0.8–1.1; Co, 2.6–2.9; Cu, 3.3–4.2; Hg, 0.09–0.15; Mn, 6.3–9.1; Ni, 1.2–2.4; Zn, 120–140.