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.     

(Laser-excited) Shpol'skii fluorometry: applications in marine environmental analysis of polynuclear aromatic hydrocarbons

Shpol'skii spectroscopy is a technique that can be employed to obtain highly resolved spectral signatures of molecules. The high-resolution spectra are obtained by using n-alkanes as solvents that form neat crystalline matrices at low temperatures. The specificity and sensitivity of the Shpol'skii method can be further improved by application of selective laser excitation. Summarizing, Shpol'skii spectra show the highly specific fingerprinting properties of IR spectra, but at the same time have the inherently high sensitivity of fluorescence techniques.In this paper attention will be given to principles and general experimental aspects of the Shpol'skii technique. Furthermore, some applications in environmental analysis will be discussed in more detail: (1) the qualitative determination of polycyclic aromatic hydrocarbons (PAH) in suspended matter collected in estuarine water; (2) the quantitative determination of PAH in NRCC sediment reference material SES-1; and (3) the application of laser-excited Shpol'skii spectroscopy for the qualitative determination of PAH in crude extracts of biotic samples. It is shown that the Shpol'skii technique can be used successfully as an independent reference method for both qualitative and quantitative checks of conventionally used determination methods. Because of the high selectivity of the low-temperature method, PAH can be quantitatively determined without any sample clean-up, even in extremely complex biotic samples.     

Effects of polynuclear aromatic hydrocarbons on lysosomal membranes in molluscs

Lysosomal sequestration of polynuclear aromatic hydrocarbons (PNAHs), a major class of environmental contaminant, is a well-established phenomenon;¹ considerably less is known about their pathological effects on lysosomes. Marine molluscs contain a number of lysosome-rich tissues and PNAHs are known to induce deleterious alterations in lysosomal structure and latency of lysosomal enzymes.² The latter are presumed to involve destabilisation of the lysosomal membrane, resulting in increased permeability and reduced enzyme latency. If lysosomal injury involves derangement of membrane-lipid structure due to the interaction of PNAHs then it would be expected that membrane damage would be closely linked to the structural characteristics of the intruding molecule. Our results show that the effects of the isomeric PNAHs phenanthrene and anthracene on digestive cell lysosomal stability were markedly different in the marine mussel (Mytilus edulis) over the same range of tissue concentrations. Lysosomal membrane stability was determined using a cytochemical test for enzyme latency.³     

Effects of polynuclear aromatic hydrocarbons on fishes and shellfish: An overview of research in virginia

This paper discusses the following topics related to polynuclear aromatic hydrocarbon pollution in estuaries: (1) the use of oysters (Crassostrea virginica), hard clams (Mercenaria mercenaria) and brackish water clams (Rangia cuneata) in residue monitoring; (2) the effects of elevated PAH residues on oyster condition; (3) three years of field studies relating PAH sediment contamination to abnormalities in fishes; and (4) laboratory bioassays for effects and bioconcentration modeling. Oysters, hard clams and Rangia have been shown, from 3 years of field studies, to be good monitors of pollution inputs as one proceeds along salinity gradients from 25‰ to 0·5‰. Effects of increased body burdens of PAHs are shown by a lowering of the oysters' condition index, as measured by lipid levels. Fishes inhabiting the Elizabeth River, VA, which is highly contaminated with PAHs, have abnormalities (cataracts, skin lesions, abnormal fins, etc.). These abnormalities have higher incidence in regions of the river where the sediments are more heavily contaminated. Laboratory studies utilizing contaminated sediments have reproduced some of the abnormalities observed in the field. Bioconcentration of PAHs from sediments has been studied with oysters and hard clams. Oysters generally accumulate three times the body burdens of clams exposed to the same suspensions. A faster depuration rate (k₂) for clams appears to be responsible for the higher equilibrium body burden of oysters.     

Responses of the mixed function oxidase system of some bivalve and gastropod molluscs to exposure to polynuclear aromatic and other hydrocarbons

Bivalve and gastropod molluscs readily accumulate polynuclear aromatic (PNAH) and other hydrocarbons from the environment and are widely used in environmental monitoring programmes.¹ The response of the cytochrome P-450 monooxygenase or mixed function oxidase (MFO) system to organic xenobiotics is of interest from the comparative viewpoint and in biological effects monitoring.² We have studied the bivalves Mytilus edulis (mussel) and Cardium edule (cockle) and the gastropod Littorina littorea (periwinkle) exposed to hydrocarbons, experimentally or naturally in the field. The general trend of response in digestive gland microsomes was an increase in cytochrome P-450 content and NADPH-cytochrome c reductase (NADPH-CYTCRED) activity but no increase in benzo[a]pyrene hydrolyase (BPH) activity. Sex and seasonal interactions were evident. We conclude that aspects of the responses may be peculiar to the Mollusc and that NADPH-CTYCRED possibly offers potential for this phylogenetic group as a specific indicator of biological impact by organic pollution.     

多环芳烃化合物对栉孔扇贝组织芳烃羟化酶活力的影响

研究了苯并(a)芘(B[a]P)、苯并(k)荧蒽(B[k]F)以及两者的混合物对栉孔扇贝(Chlamys farreri)鳃丝和消化盲囊芳烃羟化酶(AHH)活力的影响。结果表明,多环芳烃化合物(PAHs)对栉孔扇贝鳃丝和消化盲囊AHH活力具有显著的诱导作用(P<0.05),并且呈现了明显的时间、剂量效应特征。B[a]P和B[k]F混合物处理组鳃丝和消化盲囊的AHH活力在实验期间呈现先升高后稳定趋势,B[a]P处理组则表现峰值变化,然后呈下降趋势。消化盲囊各处理组AHH活力显著高于鳃丝。作者认为可以采用消化盲囊的AHH活力来反映周围环境PAHs的污染,并应以最大饱和浓度为标准。3种PAHs中B[a]P的毒性最强,PAHs对栉孔扇贝的毒性大小与PAHs的组成有关,不能以不同种类单一PAHs毒性的总和来代表PAHs混合物的毒性。     

Physiological responses of Mytilus edulis during chronic oil exposure and recovery

Physiological responses of mussels Mytilus edulis were determined following 8 months' exposure to two oil concentrations (28 and 125 μg litre⁻¹ total hydrocarbons) and during the process of recovery. There was a significant inverse relationship between the performance of Mytilus edulis, measured in terms of scope for growth, and the concentration of aromatic hydrocarbons accumulated in the body tissues. The marked reduction in scope for growth of oil exposed mussels was primarily due to a reduction in feeding rate and food absorption efficiency. Recovery of physiological responses was coupled to the depuration of aromatic hydrocarbons from the body tissues. Mussels exposed to high-oil concentrations were found to recover more rapidly than those exposed to low-oil concentrations, both in terms of depuration and scope for growth, and there was evidence of ‘catch-up’ growth. Recovery of mussels from both oil conditions was complete after approximately 55 days.     

Bioenergetic responses of the marine bivalve Venus verrucosa on long-term exposure to petroleum hydrocarbons

A number of physiological responses of the bivalve Venus verrucosa on exposure to low levels of water accommodated fractions of Kuwait crude oil (100 μg litre⁻¹) for 145 days were investigated in the laboratory. Such exposure led to significant decreases in clearance or feeding rates and in the food absorption efficiencies, as well as enhanced oxygen consumption and ammonia excretion. The integration of such physiological responses to assess the scope for growth, as well as the oxygen to nitrogen ratio, indicated that such exposure led to a significant drop in the energy available for somatic growth and reproduction and enhanced protein catabolism (this being indicative of stressed conditions). These results were also confirmed by significant reductions in several body condition indices of the exposed bivalves relative to the controls. The ecological significance of such results is discussed.     

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.     

Behavioral responses to ocean acidifi cation in marine invertebrates:new insights and future directions

Ocean acidification(OA)affects marine biodiversity and alters the structure and function of marine populations,communities,and ecosystems.Recently,effects of OA on the behavioral responses of marine animals have been given with much attention.While many of previous studies focuses on marine fish.Evidence suggests that marine invertebrate behaviors were also be affected.In this review,we discussed the effects of CO2-driven OA on the most common behaviors studied in marine invertebrates,including settlement and habitat selection,feeding,anti-predatory,and swimming behaviors,and explored the related mechanisms behind behaviors.This review summarizes how OA affects marine invertebrate behavior,and provides new insights and highlights novel areas for future research.     

海洋微藻对UV-B辐射的生理生化响应

用生理生化的方法研究了UV-B辐射对海洋微藻———小新月菱形藻(Nitzschia closte-rium)生理生化的影响。结果表明:(1)随着UV-B暴露时间的延长,UV-B辐射对藻的生长以及光合速率有抑制作用,并且时间越长,抑制作用越明显;(2)UV-B辐射使小新月菱形藻可溶性糖含量降低,而且在最初的2d,UV-B辐射使可溶性糖含量降低迅速,第4天的可溶性糖含量稍有所升高但与第2天相比差异不显著,UV-B辐射第6天,可溶性糖含量又迅速降低;(3)UV-B辐射的可溶性蛋白含量在第2天明显升高,随后又快速下降;(4)对照组的还原型谷胱甘肽(GSH)含量的变化随时间延长而升高,UV-B辐射第2天的GSH含量比初始状态(0d)的GSH含量稍有升高,但变化不明显,第2天之后,GSH含量随时间延长而快速降低;(5)对照组的过氧化物酶(POD)活性随时间延长而升高,UV-B辐射第2天的POD活性比初始状态(0d)的POD活性显著升高,第2天之后,POD活性随时间延长而快速降低。     

Variability of gas composition and flux intensity in natural marine hydrocarbon seeps

The relationship between surface bubble composition and gas flux to the atmosphere was examined at five large seeps from the Coal Oil Point seep field (Santa Barbara Channel, CA, USA). The field research was conducted using a flux buoy designed to simultaneously measure the surface bubbling gas flux and the buoy’s position with differential GPS, and to collect gas samples. Results show that the flux from the five seeps surveyed a total of 11 times ranged from 800–5,500 m³ day^?1. The spatial distribution of flux from the five seeps was well described by two lognormal distributions fitted to two flux ranges. The seafloor and sea surface composition of bubbles differed, with the seafloor bubbles containing significantly more CO₂ (3–25%) and less air (N₂ and O₂). At the sea surface, the mole fraction of N₂ correlated directly with O₂ (R ² = 0.95) and inversely with CH₄ (R ² = 0.97); the CO₂ content was reduced to the detection limit (<0.1%). These data demonstrate that the bubble composition is modified by gas exchange during ascent: dissolved air enters, and CO₂ and hydrocarbon gases leave the bubbles. The mean surface composition at the five seeps varied with water depth and gas flux, with more CH₄ and higher CH₄/N₂ ratios found in shallower seeps with higher flux. It is suggested that the CH₄/N₂ ratio is a good proxy for total or integrated gas loss from the rising bubbles, although additional study is needed before this ratio can be used quantitatively.     

Sex-specific biochemical and histological differences in gonads of sea urchins (Psammechinus miliaris) and their response to phenanthrene exposure

Female and male individuals of the same species often differ with respect to their susceptibility to toxicant stress. In the present study, sea urchins (Psammechinus miliaris) of both sexes were exposed to high (150 μg L?1) and environmentally relevant (5 μg L?1) concentrations of phenanthrene over 10 days. While food intake was significantly decreased following exposure to 150 μg L?1 phenanthrene, histological indices (lipofuscin accumulation, fibrosis, oocyte atresia), energetic status (energy charge, sum adenylates, AMP/ATP ratio) as well as ascorbate levels in the gonads showed either little or no effect upon phenanthrene exposure. However, most parameters (vitamin C, energy charge, sum adenylates, AMP/ATP ratio, ATP and ADP concentrations, lipofuscin content, fibrosis) significantly differed between male and female animals. This study illustrates the difficulties to identify toxic injury in reproductive tissue as it may be superimposed by gametogenesis and spawning of gametes.     

Cellular responses to polycyclic aromatic hydrocarbons and phenobarbital in Mytilus edulis

Certain polycyclic aromatic hydrocarbons and phenobarbital induced an increase in the activity of microsomal NADPH neotetrazolium reductase (linked to mixed function oxygenase systems) in the blood cells of Mytilus edulis. Phenanthrene and methylated naphthalenes caused lysosomal destabilisation which is believed to be directly related to the mechanism of cytotoxicity in the digestive cells. The use of these cytochemical techniques as indices of aromatic hydrocarbon contamination is discussed.     

Adaptative responses of E. coli to marine environmental stresses: a modelling approach based on viability and dormancy concepts

In an attempt to synthesize conceptual and experimental information on the behaviour of enteric bacteria in seawater, a mathematical model has been developed. This model is based on changes in intracellular metabolisable components depending on physiological responses of the cell when subjected to nutrient starvation, salinity stress and solar radiation. Following a strategy which takes into account short- and mid-term physiological adaptation and reversal processes, the cells can develop in different states: culturable (B₁), viable and definitively nonculturable (B₂), and reversibly dormant (B₃) cells. Model parameters were deduced either from original microcosm experiments, from literature data or calibration procedures. Validation of the model was performed through specific data on the patterns of change in culturable cell abundances when Escherichia coli populations were subjected to separate or simultaneous experimental stresses. It was shown that model simulations fit these data satisfactorily. Simulation results clearly show the effectiveness of the antistress response and the importance of dormancy which confers higher resistance properties. The model also makes it possible to test the effect of the different stresses, and the role of pre-adaptation with regard to the dynamics of the different cellular states.     

Effects of a marine ridge to western boundary current in a three-dimensional source-sink flow model

A numerical experiment is made with a three-dimensional source-sink flow model in order to study effects of a marine ridge to the western boundary current. The model represents the Kuroshio current crossing the Izu Ridge which has a submarine narrow passage. It is indicated that most of the surface water of the western boundary current crosses the ridge through the narrow passage. A part of the surface water circulates around a warm eddy formed in an upstream region of the ridge. A water below the thermocline makes a long detour around the ridge and forms a subsurface northward current along the eastern slope of the ridge.