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1.
These studies were designed to determine the metabolic capability of the microsomal cytochrome(s) P-450 in spiny lobster hepatopancreas, and to determine how chemicals which selectively modify mammalian monooxygenase activity catalyzed by different cytochrome P-450 isozymes affect the spiny lobster cytochrome P-450. We used a washing procedure to concentrate the hepatopancreas microsomal cytochrome P-450 and remove the inhibitors of monooxygenase activity which are normally present in microsomes. The resulting reparation (MI fraction) was used to determine monooxygenase activity towards benzo[a]pyrene, benz-phetamine, 7-ethoxyresorufin in the presence of either cumene hydroperoxide or NADPH and vertebrate liver cytochrome P-450 reductase. Benzphetamine was the best substrate for the lobster cytochrome P-450, whereas 7-ethoxyresorufin was metabolized very slowly. Studies with chemical modifiers showed that the responses of the lobster cytochrome(s) P-450 were not similar to those of any of the well-characterized cytochrome P-450 isozymes purified from mammalian liver.  相似文献   

2.
Cytochrome P-450 monooxygenases catalyze the biotransformation of a great variety of foreign, as well as endogenous, lipid-soluble compounds to more water-soluble products. As in mammals, highest concentration of cytochrome P-450 in fish is found in the liver. However, previous studies have indicated that fish kidney contains relatively high cytochrome P-450-mediated activities.1,2 We have therefore prepared and characterized subcellular fractions from the kidney of rainbow trout suitable for studies on cytochrome P-450-dependent reactions. Furthermore, as in the liver, several cytochrome P-450-mediated reactions in the kidney were induced following treatment of the fish with β-naphthoflavone.  相似文献   

3.
Monooxygenase reactions catalyzed by cytochromes P-450 are paramount in the oxidative metabolism of many xenobiotics, determining both the persistence and effects of numerous types of compounds. Immunological probes are proving useful in evaluating the functions of P-450 isozymes in microsomal preparations from many species. The regulation of specific isozymes by endogenous and exogenous factors can also be evaluated with such probes. Here we describe studies on the activities apparently catalyzed by induced P-450 in fish, evaluated with both polyclonal and monoclonal antibodies to cytochrome P-450E, the apparent major β-naphthoflavone(BNF) or methylcholanthrene(MC)-inducible isozyme purified from scup (S. chrysops) liver.  相似文献   

4.
Increasing anthropogenic pollution of the environment can have adverse consequences for organisms which are more subtle than direct toxicity. Detectable levels of persistent pollutants remain even if the substance is no longer used. An example is atrazine, a herbicide in common use throughout the world but one which has been banned in Germany since 1992. As a lipophilic substance, atrazine is bioconcentrated which may lead to chronic intoxication or physiological stress. In order to withstand chemical stressors, many organisms possess detoxication enzymes, for example certain P-450 monoxygenases and glutathione S-transferases. But detoxication demands cellular energy, and in developing organisms, such as fish embryos which have particularly high energy needs for sustaining growth and organogenesis, the additional energy needs of detoxication may present additional stress. In this study, uptake of atrazine, cytochrome P-450 binding spectra, effects on microsomal and soluble glutathione S-transferase activities, and the initial detoxication steps of atrazine via microsomal and soluble glutathione S-transferases were studied using early life stages of zebrafish.  相似文献   

5.
The monooxygenase cytochrome P-450 is a ubiquitous enzyme well known for its role in the detoxication of drugs and xenobiotics and the biosynthesis of the steroid hormones. The toxicity and carcinogenicity of many chemicals is frequently due to the formation of oxygenated reactive intermediates, which are formed by the same enzymes that effect the detoxication of these chemicals, namely the cytochromes P-450. In mammalia the cytochromes P-450 exist as a group of isoenzymes with overlapping substrate affinities, selectively and differentially induced by their specific substrates or inhibitors. As few enzyme assays have been shown to be specific for a particular cytochrome P-450 isoenzyme the characterisation of these isoenzymes has been dependent on their isolation and purification. It is therefore important to know whether one or more isoenzyme of cytochrome P-450 is specifically concerned with the activation of carcinogens and chemicals, rather than their detoxication, and to develop a specific enzymic assay for this activating enzyme.  相似文献   

6.
The hepatic mixed function oxidase system in the fish differs from that in mammals in its responses to the two classic mammalian inducers. The cytochrome P-448-type inducers (polycyclic aromatic hydrocarbons) stimulate monooxygenase activity, but phenobarbital, a P-450-type inducer, does not.1 We have compared the effects of phenobarbital (PB) and polychlorinated biphenyls (PCB) on the turnover of hepatic microsomal hemoproteins in trout (PCB's are P-448- and P-450-type inducers in mammals, which in fish induce only cytochrome P-448). We show here that neither PCB nor PB treatment changed the turnover rate. However, both the rates of synthesis and degradation were much slower than in the rat.  相似文献   

7.
Monoclonal antibody directed against a major β-naphthoflavone (BNF)-induced form of teleost cytochrome P-450, P-450E (equivalent to P-450c in rat) was used to immunolocalize this enzyme in liver, gill and heart of scup and trout. Liver sections from both species showed P-450E in the cytoplasm of hepatocytes. No regional differences were observed which might indicate zonation of cytochrome P-450E within subpopulations of hepatocytes. Scup exocrine pancreatic cells were only weakly positive. In the gill of both fish, cytochrome P-450E was restricted to the endothelium (pillar cells) of secondary lamellae, where fluorescence appeared as a chain in longitudinal sections through lamellae and as star-shaped clusters in en face views. Sections of ventricular wall in both species revealed P-450E was restricted to endothelium at margins of muscle bands limiting heart ventricular lumen. Localization in the specific cells of these and other organs may be fundamentally important in understanding the role of cytochrome P-450E.  相似文献   

8.
This study was conducted to test whether live cells from the liver of fish could be used to detect early changes that are indicative of pollutant-induced liver damage. Low-molecular-weight fluorescent molecular probes were inserted into isolated hepatocytes from dab (Limanda limanda) from a contaminated site and a reference site in the North Sea. These included bioprobes for endoplasmic reticulum (ER), cytochrome P-450-associated 7-ethoxyresorufin-O-deethylase (EROD), oxyradicals, reduced glutathione (GSH) and microtubules (MT). Endocytosis of Texas Red-albumin was used as an integrated indicator of hepatocyte performance. Findings showed increases in ER-associated fluorescence, EROD and oxyradical generation, with a marked decrease in endocytosis in hepatocytes from fish caught at the contaminated site. These results indicate that fish from the historically contaminated site were impacted by organic xenobiotics which induced the biotransformation system, radical production and cell injury.  相似文献   

9.
The aim of this research was to study spatial and temporal variation in epiphyte cover and leaf biomass of Posidonia oceanica in Eastern Tunisia. Sampling was conducted at four stations on the Mahdia coast during October and December 2010, and April and August 2011, which correspond respectively to autumn, winter, spring and summer in this area. Posidonia oceanica shoots were collected at two depths (5 and 10 m). Cover of macroinvertebrates and macroalgae was estimated on adult leaves. The results showed that leaf and epiphyte biomasses vary significantly according to sampling date, with the highest values recorded in August. We found a high diversity of epiphytic assemblages on the leaves of P. oceanica with clear qualitative and quantitative dominance of Rhodophyceae compared to other groups, followed by Phaeophyceae. Most epiphyte species on the leaves of P. oceanica in Eastern Tunisia are the same as those in other parts of the Mediterranean Sea. No bathymetrical variation in the epiphytic community was found in our study area, which can be explained by the high levels of water clarity in Mahdia.  相似文献   

10.
In this study we have used cloned gene probes for human glutathione peroxidase (GPX), rat cytochrome P-450IVA1 and rat cytochrome P-450IIE1 to detect homologous sequences in RNA from the hepato-pancreas of Mytilus edulis. The presence of sequences hybridising to the GPX and P-450IVA1 probes, but not to the P-450IIE1 probe, confirms the ancient origin of the former genes and indicates that conserved-sequence DNA probes from higher organisms can be used to examine the structure and function of genes of environmental interest in marine organisms.  相似文献   

11.
The whales are an interesting group in several aspects of science, including evolutionary biology, marine ecology and toxicology. Some of the whale species, including the minke whale, graze at the top of the food chains, where they become susceptible to the accumulation of marine pollutants ingested by organisms at lower levels. The northern stock of the minke whale grazes in Arctic waters in the summer, an area of increasing interest in the development of new oil fields. Studies on the metabolism, disposition and effects of xenobiotics in marine mammals are few. The only reports in the open literature so far have dealt with these questions in seals.1–3 Although the marine mammals comprise a particularly interesting group in marine ecology and toxicology, no data have to our knowledge been presented on the xenobiotic metabolising enzyme systems of the whales. In this study, components of the microsomal cytochrome P-450 system were measured in liver samples from several females, one male, and two foetal minke whales, caught in the Norwegian whaling season of 1983. Because of the limited number of samples studied we have treated the samples individually and not performed any statistical analysis of the data. The trends discussed below must therefore be considered with this background.  相似文献   

12.
Seagrass meadow characteristics, including distribution, shape, size and within‐meadow architectural features, may be influenced by various physical factors, including hydrodynamic forces. However, such influences have hardly been assessed for meadows of the ecologically important and endemic Mediterranean seagrass Posidonia oceanica. The distribution of P. oceanica meadows at five sites in the Maltese Islands was mapped to a depth of c. 15 m using a combination of aerial photography and SCUBA diving surveys. Estimates of wind‐generated wave energy and energy attenuated by depth were computed using the hydrodynamic model WEMo (Wave Exposure Model). Metrics for P. oceanica landscape features were calculated using FRAGSTATS for replicate 2500 m2 subsamples taken from the seagrass habitat maps in order to explore the influence of wave dynamics at the landscape scale. Data on within‐meadow architectural attributes were collected from five sites and analysed for relationships with wave energy. The results indicate that landscape and architectural features of P. oceanica meadows located within the 6–11 m depth range are significantly influenced by wave climate. Posidonia oceanica meadows tend to be patchier and have low overall cover, more complex patch shapes and reduced within‐patch architectural complexity along a wave exposure gradient from low to high energy. The findings from the present study provide new insight into the influence of hydrodynamic factors on the natural dynamism of P. oceanica meadow landscape and architecture, which has implications for the conservation and management of the habitat.  相似文献   

13.
The metabolism of some xenobiotics can lead to the formation of reactive intermediates with mutagenic/carcinogenic properties. With the carcinogenic PAH these have been identified as bay-region diol-epoxides.1 Phenanthrene, a non-carcinogenic, bay-region containing model PAH, is metabolised in vivo by bony fish at the proximate bay-region position, whereas mammals and other marine organisms mainly form the K-region metabolite 9,10-dihydro-9,10-dihydroxy-phenanthrene.2 We wanted to investigate this difference more closely by studying the regiospecificity of phenanthrene metabolism in vitro both with microsomes from differently pretreated cod and with isolated cytochrome P-450 isozymes from BNF-induced cod.3 Secondly, by preparing antibodies to the major isozyme isolated (called cod P-450c), we investigated the immunochemical properties of the variously treated cod liver microsomes.  相似文献   

14.
Uptake and loss kinetics of Zn, Ag, Cd, 134Cs, and 241Am by shoots of the seagrass Posidonia oceanica and fronds of the green alga Caulerpa taxifolia were determined in controlled laboratory radiotracer experiments using low contaminant concentrations. The two species accumulated most of the elements efficiently. The only exceptions were 134Cs in both P. oceanica and C. taxifolia and Cd in C. Taxifolia (concentration factors 6.4). Steady state in uptake was reached in C. taxifolia for each element except Ag. In P. oceanica, steady state was noted for the uptake of Ag and 134Cs whereas Zn, Cd, and 241Am were linearly accumulated during the course of the experiment (15 d). With respect to relative metal bioavailability, the different compartments of P. oceanica shoots were generally ranked in the order: leaf epiphytes > adult LEAVES = intermediate leaves > leaf sheaths. The long-lived component of the loss kinetics for each element in P. oceanica was characterized by a relatively short biological half-life (Tb1/2 28 d). However, observations for the individual compartments indicated that adult leaves had a high retention capacity for Ag and 134Cs, with virtually 100% retained after 21 d in uncontaminated sea water. In C. taxifolia, the long-lived component of the loss kinetics for each element was characterized by a Tb1/2 value that was not significantly different from infinity, an observation which suggests that a substantial fraction of the metal or radionuclide incorporated during a contamination event would be irreversibly bound by this algal species.  相似文献   

15.
Posidonia oceanica meadows form the most representative community of the Mediterranean shores. However, Posidonia oceanica meadows are fragile and in a bad way because of pollution and other nuisances. In several areas, Posidonia meadows have been replaced with vast deserts of dead ‘mattes’ or sand and mud.We owe to Cooper, now dead, the idea of using derelicts of Posidonia to regenerate the meadows in the areas where the aggressive factors were eliminated. For that purpose he perfected a kind of concrete frame called ‘constraint’ which offers optimal conditions for these cuttings to take root.So a study of scientific evaluation of Cooper's method has been undertaken in an experimental field of about 10 000 m2 in the bay of Cannes. The ‘constraints’ were implanted over a period of 10 years, which gives particularly favourable conditions for studying their development. The work consisted of quantifying the vitality and the capacity of development of these cuttings with the help of classical tests such as the number of foliar bundles by surface unit, the biomass, the productivity, the number of running rhizomes and the surface of conquered ground. The results prove the effectiveness of the method which is now operational on a large scale.We can now foresee and hope for a reconquest of the ruined bottoms, provided of course we first remove the causes of the disappearance of the natural meadows of Posidonia oceanica.  相似文献   

16.
Posidonia oceanica is a slow growing seagrass species that extends via growing rhizomes that grow only centimetres both horizontally and vertically each year. Posidonia oceanica forms topographically complex biogenic reefs of dead rhizome and sediments that are up to 4 m in height that are called “matte”. This study investigates the role of slow horizontal and vertical growth of rhizomes in the formation of topographic complexity in P. oceanica matte using agent-based modelling. The simulated infilling of landscapes by P. oceanica was run over 600 iterations (years) for 10 random starts of 150 agents each. Initial infilling rates were very slow and P. oceanica had limited cover after a century of growth. Growth accelerated after 100 years but plateaued after 400 years such that after 600 years only two-thirds of the landscape was occupied by P. oceanica. The pattern of spread of agents was initially random in direction but after larger patches were formed spread was radial from these patches. The seagrass landscape was initially highly fragmented with many small separate patches made up of a few agents each, with a Landscape Division index close to 1. Between 300 and 600 years Landscape Division declined sharply to 0.42, indicating patches had coalesced into larger more continuous meadows forming a less fragmented landscape. Perimeter to area ratio of seagrass patches declined exponentially from >1 to approximately 0.2 over 600 years of simulation. The matte developed from growth of patches and its greatest height occurred in more continuously occupied cells of the grid. The topography of the reef that occupied two-thirds of the landscape after six centuries of growth could be described as a pattern of channels between reef plateaus elevated 1–2 m above channels. These results demonstrate that development in P. oceanica meadows of three-dimensional structure, in the formation of biogenic reefs, can be explained by, and is an emergent property of, slow horizontal and vertical rhizome growth rates combined with the time it takes for the accumulation of rhizomes in any region of the landscape. As such, the model provides a parsimonious explanation for the development of complex matte topography.  相似文献   

17.
《Oceanologica Acta》1999,22(1):95-107
While the extension of aquaculture along the coasts of the Mediterranean islands is today an economic priority, no data is available on the impact of these facilities on the littoral environment in general, and in particular on the Posidonia oceanica meadows that are responsible for the richness and diversity of these biotopes. The impact of fish farming facilities in the marine littoral environment is assessed at three Mediterranean sites in Corsica and Sardinia. Various parameters are considered: (i) the amount of light available, (ii) the nature of the sediment, and (iii) the vitality of the Posidonia oceanica beds. The findings confirm the impact of the aquaculture facilities within the water column (increase in turbidity, enrichment of the sediment in organic matter and nutrients), and it would appear that the Posidonia oceanica beds also undergo significant alterations. The decline in density of the meadows in the area influenced by aquaculture farming and their total disappearance beneath the facilities is particularly disturbing, even if the areas affected are not very extensive, at least for the smaller farms (a few hundred square metres), and if certain beneficial effects may be recorded (increase in benthic primary production). Because of its ability to record environmental alterations caused by these facilities (light, nutrients, trace metals), the Posidonia oceanica meadow is a good bioindicator for use in monitoring studies.  相似文献   

18.
Abstract

Artificial neural networks (ANN) have been widely used successfully to solve coastal engineering problems. In this article, they are used to model the cross-shore profile of sandy beaches taking into account the possible effect of marine vegetation (Posidonia oceanica). Sixty ANNs were generated by modifying both the inputs and the number of neurons in the hidden layer. The best results were obtained with the following inputs: wave height perpendicular to the coast and the associated period and probability of occurrence, median sediment size, profile slope, and energy reduction factor due to P. oceanica. With these inputs and 10 neurons in the hidden layer, a mean absolute error of 0.22?m during training and 0.21?m during the test was obtained, which represents an improvement of 81.2% and 55.5% compared to models without and with P. oceanica.  相似文献   

19.
Although grazing is considered an essential process controlling epiphyte biomass on seagrass leaves, there is still a lack of fundamental knowledge about the species‐specific consumption rates of the most common grazers in Mediterranean meadows. This study experimentally assessed the effect of Posidonia oceanica‐associated gastropod grazing on early successional biofilm and the species‐specific relationship between biofilm consumption rates and biofilm biomass. Two biofilms on artificial substrata, both developed in situ (in a P. oceanica meadow), one under ambient conditions and the other under nutrient‐enriched conditions, were offered in aquaria assays to nine species of grazers found in P. oceanica meadows. Biofilm consumption rates and their association with biofilm biomass were assessed. It was found that: (i) there was a positive association between biofilm consumption and biofilm biomass up to 20 mg Chl a·m?2 for Bittium reticulatum, Gibbula ardens, Jujubinus exasperatus and Tricolia pullus; (ii) Alvania montagui, B. reticulatum and Jujubinus striatus showed the highest consumption rates and are thus expected to be amongst the leading consumers in early‐successional epiphytic communities; (iii) there was not an increase of consumption rate when a substratum colonized under nutrient‐enriched conditions was offered to any of the nine studied species. This study provides species‐specific consumption rates knowledge that is useful for the assessment of the strength of grazer–epiphyte interactions and trophic fluxes in P. oceanica meadows.  相似文献   

20.
Selective accumulation of PCDDs, PCDFs and PCB congeners was investigated in beluga (Delphinapterus leucas), narwhal (Monodon monoceros) and several species at the same trophic level in two areas of Canada. There was a much higher relative abundance of meta-para-unsubstituted PCBs in the cetaceans compared with other species. This suggests that activity of cytochrome P450 monooxygenase enzymes causing CYP2B-type metabolism was relatively low in beluga and narwhal. Lower relative levels of 2,3,7,8-TCDD occurred in beluga from both areas, and selective reduction of toxic non-ortho PCBs occurred in the highly PCB-contaminated St Lawrence beluga. These compounds are potent inducers of cytochrome P450 CYP 1A-type enzymes, suggesting that such an enzyme with the capability of metabolizing TCDD-like substrates is present in beluga and narwhal. SIMCA principal components analysis of PCB congener patterns showed that the two cetaceans were in a statistically significant different class than the other species. Variables (congeners) with the greatest separation power between classes were mainly those defined by the selective metabolism rules.  相似文献   

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