Preference-avoidance reactions of crayfish to sublethal concentrations of cadmium

The preference-avoidance reactions of the crayfish, Cambarus acuminatus, exposed to nominal cadmium concentrations of 125.0, 12.5, and 1.25 µCd⁺⁺/1 are examined. Pooled data from five trials at each treatment concentration demonstrate a statistically significant avoidance of the highest concentration, and preference for middle and lowest concentrations. Additional observations of behavior indicate that crayfish sense sublethal cadmium concentrations and respond to them with a general decrease in activity. Therefore, the use of crayfish locomotor activity as a potential parameter for continuous biological monitoring systems appears feasible.     

Haematological and biochemical parameters and tissue accumulations of cadmium in Oreochromis niloticus exposed to various concentrations of cadmium chloride

Oreochromis niloticus, weighing 36.45 ± 1.12 g were exposed to 10%, 20% and 30% of the LC₅₀ of CdCl₂ which represents treatments (T1)1.68, (T2)3.36 and (T3)5.03 mg/l, respectively, for a period of 10, 20 and 30 days. It was found that, compared to a control group reading of 0.19 ± 0.03 μg/g dry weight, accumulation of Cd in the gills was significantly (p < 0.05) increased in samples ranging between 7.64 ± 0.86 and 61.73 ± 0.82 μg/g dry weight from T1 at 10 days to T3 at 30 days. The accumulation of Cd in the liver, meanwhile, was also observed to significantly increase (p < 0.05) with increasing time and concentrations with results ranging between 3.21 ± 0.12 and 181.61 ± 1.32 compared to the control group results of 0.29 ± 0.04 μg/g dry weight. Although muscles exhibited lower levels of accumulation than the gills and liver they still showed the same pattern of increase compared to the control group, with a significant difference ranging between 0.32 ± 0.02 and 2.16 ± 0.08 compared to the control group results of 0.03 ± 0.001 μg/g dry weight. Also, haematological parameters such as red blood cells (RBCs), haemoglobin (Hb) and haematocrit (Hct) were reduced in fish exposed to Cd at all periods, with significant differences (p < 0.05). Plasma glucose concentration showed a significant increase. Total protein levels of fish showed a significant reduction (p > 0.05) for all exposed treatments. Also, the total lipid level increased significantly as fish were exposed to increasing cadmium concentrations, compared to control fish. Finally, the activities of aspartate aminotransferase (AST IU/l) and alanine aminotransferase (ALT IU/l) showed a significant increase (p < 0.05) with increasing time and concentrations.     

Alterations in hepatic heme metabolism in fish exposed to sublethal cadmium levels

A study on hepatic heme metabolism with special emphasis to ALA synthetase, ALA dehydratase and heme oxygenase was carried out in cadmium exposed freshwater fish Channa punctatus to enlighten the mechanism of cadmium induced toxicity. Cadmium exposure (0.5-5.0 mg/1) for 7 days increased the hepatic level of ALA, along with the depletion in heme content, which are characteristic to chemical porphyria. The resultant enhancement in the activities of ALA synthetase and heme oxygenase were further shown to be dose dependent. ALA dehydratase activity on the other hand was enhanced only at higher exposure. Time course studies on the enzyme activities and heme content showed that ALA synthetase started to increase after 24 hrs., reached maximum at 7 days and came back nearly to normal level after 30 days of exposure. Simultaneously maximum depletion in heme level occurred on 7 days of exposure, tending to return to normal on 30 day. In addition, attempt has been made to correlate alterations in heme metabolism due to cadmium with the histopathological manifestations in liver.     

Increased acetylcholinesterase activities in specimens of Sparus auratus exposed to sublethal copper concentrations

The present study looks at possible changes in the activity of acetylcholinesterase (AChE) in tissues (brain and white muscle) of the Mediterranean bony fish Sparus auratus after a 20 days exposure to sublethal concentrations (0.1 or 0.5 ppm) of copper in the marine water and on control untreated animals. The trials also included measurements of Cu concentration in the tissues to evaluate possible metal accumulation. Moreover, sedimentation analysis as well as V(max) and K(m) determination were carried out in tissue extracts of Cu-exposed or control animals. V(max) and K(m) were also determined with or without addition of Cu(2+) in the assay. No Cu accumulation occurred in brain and muscle after Cu exposure. AChE showed in both tissues a molecular polymorphism with putative globular (G) and asymmetric (A) forms. Cu exposition led to an increased specific activity and improved catalytic efficiency of AChE in brain and muscle, seemingly regarding G forms. The increase in catalytic efficiency also resulted from the in vitro assay with tissue extracts and Cu(2+) addition. The higher AChE activity and catalytic efficiency in both tissues after Cu exposition and without metal accumulation, suggests an increase of free Cu aliquot into the cells, likely due to mechanisms of metal homeostasis.     

Carotenoids found in Littorina littorea and their relationship to parasitic infection by larva trematodes

Littorina littorea from Long Island Sound feed primarily on algae: Chlorophyceae (three species) and Rhodophyceae (two species). Carotenoids from the algae accumulate in tissues of the snail in either an unchanged or a metabolized state. β-Carotene, the major pigment of green and red algae, was isolated from the foot, hepatopancreas, and nephridium of these snails. Six oxygenated carotenoids, not completely identified, were isolated from the same tissues. The snails show a variation in foot color from white to brown to red. L. littorea is parasitized by trematode larvae of Cryptocotyle lingua and Cercaria parvicaudata from which β-carotene and one oxygenated carotenoid were isolated. Contrary to previous work, there is no relation between foot color of the snail and parasitic infection. Neither age nor sex appears to have any relation to foot color. Although carotenoid pigments are known to cause the variation in foot color, the reasons or factors for their accumulation in the snail tissue have not been established. Some hypothetical explanations are discussed.     

Cellular cadmium distribution in the common winkle,Littorina littorea (L.) determined by X-ray microprobe analysis and histochemistry

Summary Various tissues of common winkles,Littorina littorea (L.), experimentally exposed to cadmium (Cd) chloride were examined using light and electron microscopy and their elemental composition determined by X-ray microanalysis and histochemistry. Membrane granules in gill epithelial cells with paddle cilia contain carbonates, phosphates and sulphides associated with different cations in different types of granules. Traces of Cd have been found only in those granules containing sulphur and iron. Nephrocytes also contain small amounts of this metal in the cytoplasm of excretory cells. X-ray microanalysis reveals that concretions of basophilic cells are minor sites for Cd sequestration while BTAN-ASSG stain for unbound Cd indicates that most of the Cd is located within the lysosomes of digestive cells in association with proteins. Low amounts of the metal have been evidenced in the granules of epithelial mantle cells rich in sulphur. The results also indicate that hemocytes contain granules of calcium phosphate and iron sulphide. Cd is also associated to sulphur rather than to phosphate. These hemocytes may act as Cd carrier from gills to kidney and digestive gland. A hypothetical pathway for Cd accumulation and detoxification is suggested.     

Cellular cadmium distribution in the common winkle, Littorina littorea (L.) determined by X-ray microprobe analysis and histochemistry

Various tissues of common winkles, Littorina littorea (L.), experimentally exposed to cadmium (Cd) chloride were examined using light and electron microscopy and their elemental composition determined by X-ray microanalysis and histochemistry. Membrane granules in gill epithelial cells with paddle cilia contain carbonates, phosphates and sulphides associated with different cations in different types of granules. Traces of Cd have been found only in those granules containing sulphur and iron. Nephrocytes also contain small amounts of this metal in the cytoplasm of excretory cells. X-ray microanalysis reveals that concretions of basophilic cells are minor sites for Cd sequestration while BTAN-ASSG stain for unbound Cd indicates that most of the Cd is located within the lysosomes of digestive cells in association with proteins. Low amounts of the metal have been evidenced in the granules of epithelial mantle cells rich in sulphur. The results also indicate that hemocytes contain granules of calcium phosphate and iron sulphide. Cd is also associated to sulphur rather than to phosphate. These hemocytes may act as Cd carrier from gills to kidney and digestive gland. A hypothetical pathway for Cd accumulation and detoxification is suggested.     

Quantitative responses of the digestive-lysosomal system of winkles to sublethal concentrations of cadmium

The effects of the experimental exposure to sublethal concentrations of cadmium on the digestive gland lysosomal system of the marine prosobranch Littorina littorea have been studied by means of stereology in fresh frozen cryotome sections after demonstration of beta-glucuronidase activity. The volume density of secondary lysosomes was demonstrated to be independent of both the external concentration of the metal and the exposure-time. However, some punctual increases in this parameter have been related to the alternate renewal of the tissular population of this organelle. The lysosomal surface density showed a dose- and time-dependent significant decrease over the controls. The lysosomal surface to volume ratio increased over the time in the control series whilst decreased significantly in Cd-exposed animals at each sampling period. Lysosomal numerical density was strongly dependent on the external concentration of the metal, changes in this parameter showing the highest signification. It is concluded that sublethal exposure to cadmium leads to fusion of secondary lysosomes to give larger ones. This process is related to lysosomal membrane destabilisation, which could take place after the storage capacity of the organelles have been overloaded.     

Biomarkers of toxicity in Clarias gariepinus exposed to sublethal concentrations of polycyclic aromatic hydrocarbons

Physiological, biochemical and histological indices in Clarias gariepinus broodstock, and teratogenic indices in embryos exposed to sublethal concentrations of naphthalene, phenanthrene and pyrene were investigated in 2014 using a static-renewal bioassay protocol. Phenanthrene (1.41 mg l^?1) was the most toxic, followed by pyrene (1.53 mg l^?1) and naphthalene (7.21 mg l^?1), based on 96 h LC50 values. Hepatosomatic indices were significantly higher in naphthalene- and pyrene-treated males compared with solvent controls, whereas fecundity in females was significantly lower by factors of 2.4 (naphthalene), 2.8 (phenanthrene) and 2.4 (pyrene), compared with controls. Catalase levels were lower in female phenanthrene-treated fish compared with controls. Histological alterations observed in PAH-treated fish include oedema, inflammatory cells, epithelial lifting and hyperplasia in the gills, vacuolation, haemosiderin pigments and sinusoidal congestion in the liver, and degenerated zona radiata in the ovary. Teratogenic effects were not observed, as evidenced by the lack of histological alterations in embryos spawned from pre-exposed broodstock. Sex-specific responses and the utility of biomarkers at cellular and individual levels of organisation are therefore demonstrated for holistic evaluations of polycyclic aromatic hydrocarbons in ecotoxicological studies.     

Periphyton Architecture and Susceptibility to Grazing by Periwinkles (Littorina littorea,Gastropoda)

Periphyton was grown on transparent plastic substrata in the Kiel Fjord and used for short-term laboratory experiments to study the feeding selectivity of the periwinkle Littorina littorea in response to the vertical structure of the periphyton. The susceptibility of algae to periwinkle grazing was assessed by comparing the species-specific biomass within the grazing tracks of the snails to the biomass outside the tracks. After 3 weeks of incubation, the periphyton consisted of a scattered monolayer of algal cells without vertical structure. No apparent grazing could be found. After 6 weeks of incubation, periphyton consisted of a tightly attached undergrowth (mainly Cocconeis scutellum, Bacillariophyceae, and Myrionema sp., Phaeophyceae) and canopy of filamentous (Melosira moniliformis, Bacillariophyceae) and stalked forms (Achnanthes longipes, Bacillariophyceae). The unicellular diatoms Fragilaria tabulata and Stauroneis constricta grew partly on the primary substratum and partly as epiphytes on the canopy species. The canopy species and the epiphytes were decimated inside the grazing tracks, while the tightly attached undergrowth species appeared ungrazed.     

Demographic parameters of Brachionus calyciflorus Pallas (Rotifers) exposed to sublethal endosulfan concentrations

The effects of sublethal levels of endosulfan (0, 1, 1.5, 2.5 and 3.3 mg 1^–1) on the demography of the rotifer Brachionus calyciorus were studied. Life expectancy at birth (e _o), net reproductive rate (Ro), generation time (T) and intrinsic rate of natural increase (r) were significant differentes between blank controls and controls with acetone. The effective endosulfan concentration at which a given parameter value was reduced to 50% of the controls (EC50) was calculated for life expectancy.     

The effects of sublethal concentrations of zinc,cadmium and mercury on Euglena

Results on the effect of sub-lethal concentrations of zinc chloride (ZnCl₂), cadmium chloride (CdCl₂), and mercuric chloride (HgCl₂) on Euglena are presented. During the growth cycle respiratory oxygen uptake and photosynthetic oxygen evolution in the light are initially strongly inhibited by Zn, Cd and Hg. The effects of the three metals on photosynthesis, using oxygen evolution as a criterion was confirmed by carbon fixation techniques.Photosystem I (PSI) associated electron transport 2,6-dichlorophenol indophenol (DCPIP)_red. methyl viologen (MV) O₂, in contrast to total photosynthetic capacity, was only slightly inhibited by Zn, Cd and Hg, whereas the levels of activity of NADP-oxidoreductase in cells untreated or treated with heavy metals showed development like total photosynthesis. Metals strongly inhibited this enzyme which means that the supply of NADPH is lowered due to the action of Zn, Cd and Hg. Photosystem II (PSII) associated electron transport (H₂O dibromothymoquinone/2,3-dimethyl-5,6-methylenedioxy-D-benzoquinone O₂), however, was severely inhibited in a way similar to total photosynthesis. Effects on the cooperation of PSI + II showed patterns similar to PSII alone, i.e., heavy metals strongly reduced PSI + II dependent activities.Abbreviations DAD diaminodurene - DBMIB dibromothymoquinone - DCPIP 2,6-dichlorophenolindophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DMMIB 2,3-dimethyl-5,6-methylenedioxy-p-benzoquinone - DPC 1,5-diphenylcarbazide - MV methylviologen - PS photosystem Dedicated to Professor Kandler on occasion of his 60th birthday     

Intersex and Littorina littorea in Cork Harbour: results of a medium-term monitoring programme

Cork Harbour, located on the south coast of Ireland, is a complex, multi-user environment. In the present study Littorina littorea (L.) is used as a bio-indicator of TBT pollution, as it has a wide range within the harbour, unlike the more common bio-indicator, Nucella lapillus (L.), which is limited to rocky substrata near the mouth of the harbour. Intersex in L. littorea is used for the first time in Ireland as a medium-term indicator of TBT pollution and results show that there are no deviations in levels of intersex over the three year period from 1994–1996. These results are discussed.     

Different activity of glyoxalase system enzymes in specimens of Sparus auratus exposed to sublethal copper concentrations

The present study regards possible changes in the activity of glyoxalase system enzymes (glyoxalase I, GI, and glyoxalase II, GII) in tissues (brain, liver and white muscle) of the mediterranean bony fish Sparus auratus after a 20 days exposure to sublethal concentrations (0.1 or 0.5 ppm) of Cu in the marine water and on control untreated animals. The experiments also included measurements of copper concentration in the tissues, as well as of lactate dehydrogenase (LDH) activity, to evaluate possible Cu accumulation and changes in glycolytic activity respectively. Cu accumulation only occurs in the liver. GI, GII and LDH activities kept unchanged in the brain after copper exposure. GI activity in liver and muscle of copper-exposed animals decreases probably for a slackening in the glycolytic rate, as suggested by the lowering of LDH activity. GII activity remains unchanged or increases (liver extract, 0.5 ppm of Cu), maybe to safeguard enough cellular levels of GSH.     

Analysis of gene expression in Homarus americanus larvae exposed to sublethal concentrations of endosulfan during metamorphosis

Agricultural pesticide runoff has been suspected as the cause of numerous fish kills in rivers throughout Prince Edward Island but the impact on the surrounding marine environment is unknown. Endosulfan, an organochlorine pesticide, is a potent neurotoxin and molt inhibitor used to combat the Colorado potato beetle however it has the potential to affect non-target organisms including the American lobster (Homarus americanus). Metamorphosis is a critical stage of development and the effects of contaminant exposure during this time are largely unknown in lobster. A 14 day endosulfan exposure was performed to identify the effects on survival, development and gene expression in lobster larvae during metamorphosis; all of which were predicted to be negatively impacted. The higher endosulfan concentrations resulted in greater mortality and a significant increase in the number of days required to reach metamorphosis in surviving animals. A custom made H. americanus microarray was used for monitoring the changes in expression of 14,592 genes at the termination of the exposure. Genes with > 1.5 fold change and identified as being significant at p < 0.05 using one-way ANOVA were selected for further analysis. A total of 707 genes were identified as being significantly differentiated, however with only ~ 40% annotation of the array, the majority of these genes were unknown. Annotated genes of interest were involved in many processes: development, metabolism, immunity and oxidative stress response and gene regulation. Nine genes of interest (histone H1, farnesoic acid O-methyltransferase, cuticle protein, glutathione S-transferase, thioredoxin, NADH dehydrogenase, ecdysone nuclear receptor Fushi tarazu F1 (FTZ-F1), ferritin and ecdysone inducible protein E75 (EIP-E75)) were selected for RT-qPCR validation of the microarray results. The RT-qPCR method was more sensitive than the microarray yet detected similar expression patterns. The two highest endosulfan concentrations resulted in increased mortalities, developmental delays in reaching metamorphosis and significant changes in gene expression. This research provides a foundation for using microarray gene expression profiles as screening tools for exploring the impact of environmental contaminants on lobster.     

Histochemistry and elemental composition of the stomach cells in Littorina littorea (L.)

The present work deals with the histochemical, histoenzymological and micro-analytical study of the stomach of Littorina Littorea (L.). The results suggest the existence of intracellular digestion within the stomach cells. Thus, the occurrence of lysosomes in the mid-cytoplasm of stomach cells has been revealed by demonstration beta-glucuronidase activity in cryostat sections of frozen tissues. Other enzymatic activities have been proved with the same tissues. Accordingly, the results on lipid and pigment histochemistry indicate a certain digestion in this cell type. Mucocytes show a protective role for the epithelium, their main secretions being acid MPS. The elemental composition of electron dense concretions from the stomach cells indicate the presence of very high amounts of iron associated to lower peaks for sulphur, phosphorous and other cations found as calcium, copper and zinc.     

Light-scattering investigation of the dissociation behavior of Lunatia heros and Littorina littorea hemocyanins

The subunit structure and dissociation of the hemocyanins of two marine snails, Lunatia heros and Littorina littorea, were investigated by light-scattering molecular weight methods. The hemocyanins of both species of snails are readily dissociated to fragments of one-tenth and one-twentieth of the parent proteins of close to 9 X 10(6) daltons by either increasing the pH or using dissociating reagents of the hydrophobic urea series or some of the Hofmeister salts. The lower members of the latter group of reagents, NaCl, and to some extent also NaBr were found to have only marginal effects on the observed molecular weight transitions, suggesting that the two hemocyanins investigated possess beta-type subunits, which are known to be resistant to NaCl dissociation. The molecular weight profiles obtained with the various dissociating reagents were single inverted sigmoidal-shaped curves for both Lunatia and Littorina hemocyanins, suggesting overlapping transitions. The ultracentrifugation patterns and the species-distribution plots based on the urea dissociation data of Littorina hemocyanin suggest the presence of whole, half, and one-tenth molecular weight species in the dissociation transition region. Fitting of the urea dissociation data of Littorina hemocyanin obtained at both pH 5.7 and pH 8.0, assuming a sequential two-step dissociation scheme used in our previous studies [Herskovits, T. T., & Russell, M. W. (1984) Biochemistry 23, 2812-2819], was found to be consistent with a model of a few hydrophobic binding sites at the contact areas of the half-molecules and a much larger apparent number of binding sites (Napp) at the side to side contacts of the one-tenth molecules.(ABSTRACT TRUNCATED AT 250 WORDS)     

The importance of intraspecific competition in a Littorina littorea population in the Wadden Sea

Two field experiments were carried out totest whether effects of intraspecific competition ina Littorina littorea population can be detectedin a short-term investigation. Different size classesof L. littorea showed no significant differencein preferences when offered four kinds of eitherpossible food or substrata (Fucus vesiculosus,Ulva lactuca, Carcinus maenas, brick).Large and medium winkles preferred Fucusvesiculosus, followed by Ulva lactuca. Deadshore crabs (Carcinus maenas) were the leastpreferred objects for all size classes. On the firstday of the experiment bricks were more attractive tosmall littorines than to larger ones. Considering allfour days, the same ranking occurred for all sizeclasses: Fucus vesiculosus > Ulvalactuca > brick > Carcinus maenas. The reactionofjuveniles to increased densities was examined using anin situ caging experiment on a mussel bed. Meshsize of the cages allowed adult densities to beincreased while juveniles could escape by passingthrough the meshes. However, there was no significantemigration of small winkles even from cages with 10 to20 times natural density of large individuals. Ofgreater importance was the original number of winklesat the site. The available resources on the musselbeds appear to be sufficient to maintain a highpopulation density. Intraspecific competition does notseem to play a major role in this L. littorea-population.     

Sister chromatid exchange distribution in various human tissues exposed to MMC and BrdU

The effect of two known mutagens on different human tissues was examined in an attempt to determine if tissue specific responses exist in SCE distribution on chromosome. The tissues included human lymphocytes, skin fibroblasts, ovarian and testicular cells. All cell types were exposed to varying concentrations of 5-bromodeoxyuridine (BrdU), and mitomycin C (MMC). The numbers of SCEs were recorded from each tissue. Results indicated that certain of the tissues tested appeared more sensitive to particular agents. Results also showed that in all the tissues tested the larger chromosomes in groups A to C had greater numbers of SCEs than did the smaller chromosomes in groups D to G. There were very few SCEs in F and G group chromosomes including Y.