Morpho-histochemical changes in the liver and intestine of young giltheads (fish-nursery), Sparus aurata, L., induced by acute action of the anionic tensioactive alkylbenzene sulphonate.

In the present study we have assessed the effect on the survival and the morpho-histochemical changes in the liver and intestine of young giltheads (fish-nursery), Sparus aurata, L., induced by acute action of the anionic tensioactive, alkyl benzene sulphonate (ABS). Firstly, the LC50 of ABS at 96 hours was found to be 0.6 mg/L. Secondly, lots with 50 young giltheads (fish-nursery) were exposed to ABS concentrations of 0.5, 1, 3 and 5 mg/L, to obtain the surface tension value and exposure time required for 50% mortality of the specimens at each tested concentration. Exposure to ABS caused several forms of histopathological damage in the liver (the radial arrangement of hepatocytes was lost) and intestine (destruction of the structure of villi and increase in thickness of the other three layers). In addition, changes in bio-macromolecule components (proteins in general, siderophile proteins, neutral mucopolysaccharides, glycogen and acid mucopolysaccharides) were observed. The degree of these alterations was dependent upon the ABS concentration. These changes could have detrimental effects on the growth and survival of the species.     

Sublethal effects of experimental exposure to mercury in European flat oyster Ostrea edulis: Cell alterations and quantitative analysis of metal

Oysters display a diversity of uptake mechanisms for metallic elements and distribution in the target organs, namely gills and the digestive gland. Various tissues of the flat oyster, Ostrea edulis, were studied following experimental exposure to 0.025 m (5 g l) of mercury, for up to 34 days. All animals survived the treatment. Data indicate Hg accumulation in gill tissue with a maximum concentration of 38.76 g g dry weight after 25 days of exposure. Hg levels were lower in remaining tissues, in which the maximum concentration (18.47 mg g-1 dry weight) was reached after 18 days of exposure. After these times, concentration in both tissues decreased. Results show that oysters can accumulate Hg from the environment, without their survival being affected during the experimental period. Structural alteration of epithelial tissues of gill and digestive gland of flat oyster was comparable with effects described for other metallic elements in bivalve molluscs. Interstitial tissue was disorganized in the digestive gland, and ultrastructural changes in intracellular endomembranes were detected in epithelial cells of the digestive gland after 18 days of treatment. After 25 days, absorptive epithelial cells of gills showed highly dilated, swollen microvilli. These intracellular alterations are parameters of the incipient response to the accumulation of mercury.     

Acute effects of sodium dodecyl sulphate on the survival and on morpho-histochemical characteristics of the trunk kidney of juvenile turbot Scophthalmus maximus L

The present article reports the effect on survival as well as on the morpho-histochemical changes in the trunk kidney of juvenile turbot Scophthalmus maximus, L. induced by acute action of the anionic surfactant, sodium dodecyl sulphate (SDS). The LC50 of SDS at 96 hours was found to be 7.5 mg/l. Lots of 20 juvenile turbots were exposed to SDS concentrations of 3, 5, 7 and 10 mg/l: the exposure time required for 50% mortality of the specimens was 384,190,12 and 4 hours and surface tension values were 60.2, 56, 54.9, and 53.3 mN/m, respectively. It should be mentioned that there was a relatively high resistance to SDS of turbot compared to other teleost species, which may be related to its benthic habit. Histopathological lesions and histochemical changes that appeared in the trunk kidney of specimens exposed to the concentrations mentioned were examined. The abnormalities observed in this organ included vacuolation and desquamation of epithelial cells and degeneration of glomeruli and tubules. At the histochemical level, we appreciated some changes in the normal distribution of carbohydrates and proteins. Although the precise mechanism by which the renal tissue injury occurs is unknown, the function of this vital organ was seriously affected and this fact may ultimately play an important role in the mortality of turbots exposed to SDS.     

Sublethal effects of linear alkylbenzene sulphonate on larvae of the seabream (Sparus aurata): histological approach

Neonate (< 24 h) larvae of the seabream, Sparus aurata, were exposed to sublethal concentrations (0.1-1.0 mg x L(-1)) of the anionic surfactant Linear Alkyl-benzene Sulphonate (LAS) for 72 h under laboratory conditions. The first histopathological changes, such as peri-yolk sac edema, were observed at concentrations of 0.2 mg x L(-1). Higher exposure concentrations provoked disorganisation of the nervous system, trunk musculature and trophoblastic sincitium as well as in the digestive epithelium. Immunohystochemical CYP1A analysis, however, was not shown to be an adequate indicator of sublethal effects produced by exposure to this type of anionic surfactant     

Histological changes and micronucleus induction in the zebra mussel Dreissena polymorpha after paraquat exposure

The herbicide paraquat (PQ), still widely used in developing countries, represents a serious risk factor for human and environmental health. To test the sublethal effects of PQ on the freshwater bivalve Dreissena polymorpha, mussels were exposed to 0.125, 0.250, 0.500 mg/L for 7 and 14 days and histologically screened. PQ's genotoxic potential was also determined in haemocytes by the micronucleus, MN, assay. At concentrations > or = 0.250 mg/L, severe lesions, such as cellular vacuolation, lysis and thinness of the germinative epithelia were observed in the digestive gland and testis. A positive trend between the number of granulocytes and all PQ concentrations was observed in both gonads and digestive glands, addressing the inflammatory capacity of this herbicide on these tissues. Mussels exposed to PQ also exhibited a significant MN induction. The spontaneous MN frequencies ranged from 2.75 to 0.425 per cent, while PQ-induced MN rates in treated mussels were between 3.50 and 1.250 per cent. The histopathological effects on the digestive and reproductive systems, as well as the MN induction in the haemocytes, confirmed the cytotoxic and genotoxic effects of PQ also in D. polymorpha.     

Effects of sediment sorbed linear alkylbenzene sulphonate on juveniles of the Senegal sole, Solea senegalensis: toxicity and histological indicators

Many synthetic organic substances, including surfactants, tend to be sorbed on suspended solids and to accumulate finally on bottom sediments, where benthic communities may be exposed to them. Concentrations of Linear Alkylbenzene Sulphonates (LAS) have been detected in estuarine and coastal sediments, presenting wide concentration ranges depending on the presence of treatment facilities, hydrodynamic conditions, organic matter content etc. Senegal sole, Solea senegalensis, larvae (40 days posthatching; dph) were exposed to increasing concentrations of LAS spiked sediments, comprised between 0.37 and 880.78 mg LAS x kg(-1) during 30 days. The obtained results showed that survival of exposed larvae was not significantly affected at environmentally relevant concentrations, the LC50 value being obtained after 30 days 876.46 mg x kg(-1). However, the histological and histopathological analyses carried out in target organs revealed, that first alterations from the normal pattern were observed at concentrations of 222.66 mg x kg(-1), presenting effects such as blood extravasation and hyperplasy of the lamellar epithelium in gills, increase of inter-myotomal spaces of the skeletal musculature and edematous separation of the skin from epidermis. At the highest exposure concentrations (755.27 and 880.78 mg LAS x kg(-1)), shrinkage of hepatocytes, nuclear pycnosis and blood stagnation are observed in the liver, degeneration of pancreatic cells, reduction of hemocytopoietic tissue in the kidney and vacuolisation of intestinal enterocytes was observed at histological level, as well as severe separation of the epidermis from the underlying tissues. Simultaneously, a significant increase of the wet weight with exposure concentration was observed in the test organisms.     

Cadmium bioaccumulation and detoxification in the gill and digestive gland of the Antarctic bivalve Laternula elliptica

Exposure to a sublethal concentration of cadmium (Cd; 50 microg L(-1)) resulted in significantly increased Cd concentrations in the gill and digestive gland of the Antarctic bivalve Laternula elliptica. Continuous accumulation of Cd in the two organs during the 14-day exposure period was associated with sequestration of Cd to both the soluble cytosolic and insoluble particulate cell fractions. However, the contribution of each cell fraction to Cd sequestration differed between the two organs; in the gill, a larger portion of Cd was associated with the insoluble fraction, while in the digestive gland, both the soluble and insoluble fractions sequestered similar amounts of Cd. Metal-binding components in the insoluble cell fraction were not identified in this study. On the other hand, a metallothionein-like protein (MTLP) was the major Cd-detoxifying component in the soluble cell fraction of the gill and digestive gland. The amount of MTLP increased linearly with exposure time and the amount of Cd accumulated in the tissue, which suggests a potential utility of MTLP as a biomarker for exposure to Cd and possibly other metals.     

Acute toxicity of anionic surfactants sodium dodecyl sulphate (SDS) and linear alkylbenzene sulphonate (LAS) on the fertilizing capability of gilthead (Sparus aurata L.) sperm

In the present work we have evaluated and compared the acute toxicity of two anionic surfactants, Sodium Dodecyl Sulphate (SDS) and Linear Alkylbenzene Sulphonate (LAS) on the fertilizing capability of gilthead Sparus aurata L. sperm. The criterion used to judge exposure effectiveness was fertilization success. Spawned eggs and sperms were collected from adult giltheads. Sperms were dosed separately with different concentrations of SDS and LAS for 60 minutes. After this period, sperms and eggs were combined for 20 minutes during which fertilization took place. Finally, the number of fertilized eggs were counted and recorded to estimate the percentage of fertilization. Exposure to SDS and LAS concentrations of 0.3, 0.6, 1.5, 3 and 6 mg/L for 60 minutes caused a significant inhibitory effect on fertilization success in gilthead Sparus aurata L.. In addition, the EC50 value for gilthead fertilization after sperm exposure was found to be 2.8 mg/L and in the case of LAS it was of 2.6 mg/L. The comparison of the results from SDS and LAS shows that the latter has a stronger negative effect on sperm viability than SDS.     

The effect of chlorpyrifos on protein content and acid DNase activity in the mussel,Mytilus galloprovincialis

We evaluated the effects of short-term exposure to an organophosphate pesticide chlorpyrifos on the digestive gland and gills of the mussel Mytilus galloprovincialis. We studied metabolic activity by quantifying protein content and physiological function responses using acid DNase activity. The increase in protein content was observed in both the target tissues of mussels exposed to 0.03 μg/L chlorpyrifos when compared with control mussels. The pattern of acid DNase activity in digestive gland and gills indicated a tissue-specific response, although the lowest concentration of chlorpyrifos caused changes in acid DNase activity in both tissues. In the digestive gland, the increase of acid DNase activity was observed in mussel exposed to 0.03 μg/L chlorpyrifos, followed by decrease up to 100 μg/L chlorpyrifos. Enzyme activity in the gills showed a dose response effect. The results support the use of acid DNase activity in the digestive gland as a sensitive response to an environmentally relevant range of pesticide concentrations. It may also indicate an effect on mussel physiological status.     

Oxidative stress and histological alterations produced by dietary copper in the fresh water bivalve Diplodon chilensis

The aim of this work was to study the oxidative stress effects and histological alterations caused by dietary copper on the filter-feeding freshwater mussel Diplodon chilensis. Bivalves were fed during 6 weeks with the green algae Scenedesmus vacuolatus previously exposed to copper. Metal concentration in algae cultures and bivalve digestive gland was measured by TXRF. A maximum accumulation of 0.49 μg Cu/mg protein was detected at week 6. Also at this week, the hepatosomatic index (HSI) showed the highest decrease (50%) in response to Cu exposure. SOD and GST activities were significantly increased at weeks 4, 5 and 6, reaching an activity on average 50% higher than in controls for GST. CAT activity and GSH increased significantly at weeks 5 and 6. Despite this response, oxidative damage measured as TBARS and carbonyl groups contents increased significantly at weeks 4, 5 and 6, respectively. Digestive tubule and duct atrophy and cell-type replacement in treated mussels were observed by histological studies. The presence of intracellular rhodanine-positive granules, suggests copper accumulation in intracellular vacuoles of digestive cells.     

Histopathological Changes in Tissues of Bithynia siamensis goniomphalos Incubated in Crude Extracts of Camellia Seed and Mangosteen Pericarp

The present study was performed to observe histopathological changes in tissues of Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) incubated in crude extract solutions of camellia (Camellia oleifera) seed and mangosteen (Garcinia mangostana) pericarp, and furthermore to estimate the molluscicidal effects of 2 plant substances. Substantial numbers of bithyniid snails were incubated in various concentrations of 2 plant solution for 24 hr. As the positive control, snails incubated in various concentrations of niclosamide, a chemical molluscicide, were used. The histopathological findings were observed in sectioned snail specimens of each experimental and control groups. The results showed that both camellia and mangosteen extracts had molluscicidal effects at 24 hr with 50% lethal concentration (LC₅₀) at concentrations of 0.003 and 0.002 g/ml, respectively, while niclosamide had LC₅₀ at concentrations 0.599 ppm. B. siamensis goniomphalos snail tissues (foot, gill, and digestive system) showed disruption of columnar muscle fibers of the foot, reduction of the length and number of gill cilia, numerous mucous vacuoles, and irregularly shaped of epithelial cells. Irregular apical and calciferous cells, dilatation of the digestive gland tubule, and large hemolymphatic spaces, and irregular apical surfaces, detachment of cilia, and enlargement of lysosomal vacuoles of epidermis were also shown in all groups. By the present study, it is confirmed that 2 plants, camellia and mangosteen, are keeping some substance having molluscicidal effects, and histopathological findings obtained in this study will provide some clues in further studies on their action mechanisms to use them as natural molluscicides.     

Histopathological indices and inflammatory response in the digestive gland of the mussel Mytilus galloprovincialis as biomarker of immunotoxicity to silver nanoparticles

Background: Histopathological assessments approaches in bivalves have become an important tool in environmental toxicology. This study seeks to develop a quantitative histopathological index (Ih) and inflammation score as biomarkers in the aim to assess the health status of nanoparticles exposed mussels.

Methods: Digestive gland hematoxylin and eosin (H&;E) stained sections from Mytilus galloprovincialis were assessed after in vivo exposure (for 3, 6 and 12?h) to silver nanoparticles (Ag-NPs?Results: Silver nanoparticles clearly induced histopathological alterations in digestive gland (maximum inflammation 2.75 with AgNP?p?Ih with AgNP?p?Ih were recorded after uptake routes were blockade: AgNP?p?Conclusions: Histopathological assessments showed to be promising tool in nanotoxicity which seems to depend on nanoparticles size, exposure time and interestingly to uptake routes. It was not clear: is it the length of exposure or the size of particles is more impactful.     

Acute morphological and physiological effects of lead in the neotropical fish Prochilodus lineatus.

The present study investigated lead effects on gill morphology, hematocrit, blood sodium, glucose, lipids, protein, and cholesterol of Prochilodus lineatus exposed to two sublethal lead concentrations for 96 h. Preliminary series of short-term static toxicity tests were run to determine LC50 (96 h) of lead in P. lineatus, which was 95 mg Pb.L-1. Therefore, lead concentrations tested in the sublethal experiments were 24 and 71 mg Pb.L-1, which correspond to 25% and 75% of the LC50 (96 h), respectively. Gills of P. lineatus exposed to both lead concentrations during 96 h presented a higher occurrence of histopathological lesions such as epithelial lifting, hyperplasia, and lamellar aneurism. P. lineatus did not show significant alterations in hematocrit during exposure to both lead concentrations. Fish exposed to the highest lead concentration showed a significant decrease in Na+ plasma concentration after 48 h, possibly reflecting a sodium influx rate decrease. P. lineatus exposed to both lead concentrations presented a "classical general adaptation syndrome to stress", as hyperglycemia associated with lowered lipids and proteins was reported. Stress-response magnitude was dose-dependent. While the response to the lowest lead concentration might represent adaptation, the highest concentration seems to characterize exhaustion.     

Metal accumulation and enzyme activities in gills and digestive gland of pearl oyster (Pinctada fucata) exposed to copper

The effects of exposure to copper under laboratory-controlled conditions were investigated in the pearl oyster, Pinctada fucata. Metal accumulation and the activity of five enzymes were measured: two immune defense involved enzymes [acid phosphatase (AcPase) and phenoloxidase (PO)], two antioxidant enzymes [superoxide dismutase (SOD) and Se-dependent glutathione peroxidase (Se-GPx)] and one metal-sensitive enzyme [alkaline phosphatase (ALP)]. Analyses were carried out in gills and digestive gland of oysters exposed to 0.05 microM and 0.5 microM copper, respectively, at 12, 24, 48 and 72 h of exposure. The digestive gland of P. fucata was the main copper accumulation organ when oysters were exposed to low concentrations, whereas gills became the target organ in oysters exposed to high concentrations. The adaptation and recovery of the oysters were observed in our study. Levels of the copper accumulation and the sensitivity to copper were the main, if not, part of the reasons for the various responses of the selected enzymes. Se-GPx may potentially be used as biomarkers in biotesting of marine heavy metal pollutions. The enzymatic responses were compared with those of other studies and the possible reasons were discussed.     

Comparative histopathological alterations in the digestive gland of marine bivalves exposed to Cu and Cd.

This study compares the histopathological alterations in the digestive gland cells of mussels, Mytilus galloprovincialis and clams, Ruditapes phillipinarum following exposure to copper and cadmium. The results show degenerative processes undergone in the digestive gland ranging from inflammatory responses to extreme vacuolation, particularly in Cd-exposed individuals. Unsaturated neutral lipids tend to accumulate in pathologically enlarged lysosomes of the homogeneous-type or heterogeneous-type depending of the species and of metal. Lipofucsins containing granules were mainly found in Cu-exposed mussels and Cd-exposed clams. No granules were detected in Cd-mussels. The comparison of the methods indicate that paraffin sections are also a suitable material for the localization of lipofucsins.     

Use of metallothionein in gills from oysters (Crassostrea gigas) as a biomarker: seasonal and intersite fluctuations

The use of oyster gills for the analytical determination of metallothionein (MT) concentration as a biomarker of metal exposure was investigated. Temporal variations in MT and metal concentrations (which can interfere with inter-site differences) were examined over a 7 month period (from spring to autumn) in Japanese oysters from a clean site (Bay of Bourgneuf, France) and a metal-rich site (Gironde estuary, France) as well as in individuals translocated from the clean to the contaminated area. The ratio between the annual average of MT concentrations in specimens from the clean and the metal-rich sites was 1.3. During the last 3 months of the experiment, significant differences were no longer registered between transplants and residents from the Gironde estuary. Metals concentrations in oyster gills differed consistently between the clean and the metal-rich sites (annual average ratios of 1.5, 2.7 and 9.8, respectively, for zinc, copper and cadmium) and a fast increase in metal concentrations (over a few months) was observed in transplants, mainly for cadmium. MT and soluble metal concentrations were found to be positively and significantly correlated over the period of the study. This relationship is a positive argument for a possible use of gill MT concentration as a biomarker of metal pollution in contrast to previous findings on the digestive gland, there being a smaller amount of seasonal variability in the weight of oyster gills.     

Physiological changes in Biomphalaria glabrata Say, 1818 (Pulmonata: Planorbidae) caused by sub-lethal concentrations of the latex of Euphorbia splendens var. hislopii N.E.B (Euphorbiaceae)

Molluscides have been used as one of the strategies to control schistosomiasis. Many plant extracts with molluscidal effects have been tested, but the action of the latex of Euphorbia splendens var. hislopii is considered the most promising because it meets the recommendations of the World Health Organization (WHO). The objective of this study was to determine the lethal dose and identify the effects of the different doses of latex of E. splendens var. hislopii on the physiology of Biomphalaria glabrata submitted to treatment for 24 h. The concentrations of glucose, uric acid and total proteins in the hemolymph and of glycogen in the digestive gland and cephalopodal mass were determined. The LD50 value was 1 mg/l. The highest escape index was found to be at a concentration of 0.6 mg/l. The results showed that the latex of E. splendens var. hislopii caused a sharp reduction in the reserves of glycogen in the digestive gland and elevation of the protein content in the hemolymph of B. glabrata.     

The preconditioning phenomenon and its mechanisms in the common carp as affected by Actara insecticide

The effect of Actara insecticide on the common carp (Cyprinus carpio Linnaeus) was studied, and its sublethal concentration (LC50) for this species was estimated. Exposure to Actara at a concentration of 400 mg/L in freshwater was shown to kill all the common carp individuals within 24 h, while 24-h preconditioning at an Actara concentration of 100 mg/L promoted survival of animals when they were subsequently exposed to the insecticide at a concentration of 400 mg/L for 5 days. Estimates of serotonin-modulated anticonsolidation protein (SMAP) in the common carp brain and liver by enzyme-linked immunosorbent assay (ELISA) following exposure to Actara at a concentration of 100 mg/L for 24 h showed its increased level in both organs (p < 0.001), particularly manifest in the liver. It is concluded that preconditioning elevates SMAP tissue levels and promotes thereby protection of the organism against damaging effects of lethal Actara concentrations.