Investigation of acute toxicity of deltamethrin on guppies (Poecilia reticulata)

Deltamethrin, a synthetic pyrethroid pesticide contaminating aquatic ecosystems as a potential toxic pollutant, was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) were selected for the bioassay experiments. The 48-h LC50 was determined for the guppies. The experiments were repeated three times and a total of 210 guppies were used. The static test method of acute toxicity test was used. In addition, behavioral changes at each deltamethrin concentration were determined for the individuals. Data obtained from the deltamethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The 48-h LC50 value for guppy was estimated as 5.13 microg/L.     

Light intensity influences chromium bioaccumulation and toxicity in Scenedesmus acutus (Chlorophyceae)

The influence of light intensity on chromium uptake was studied in two strains of the freshwater unicellular alga Scenedesmus acutus (Chlorophyceae) having different sensitivity to Cr poisoning and light intensity. The two strains were subjected to different Cr treatments at 3000 and 80 lux. Cr toxicity was assessed by algal growth rate, recovery test, methylene blue staining, and determination of photosynthetic activity. After 2 and 4 days of treatment, bioaccumulated chromium, cell dry mass, and protein and carbohydrate contents were also assessed. When the algae were treated at 3000 lux, different bioaccumulation patterns were obtained when Cr content was related to dry mass, cell number, or protein content. A direct relationship between Cr content and cell mortality was observed only when the amount of Cr was related to protein content. In both strains Cr uptake was slower in subdued light, suggesting that it is linked to energy-dependent processes. The difference between the strains in sensitivity to Cr poisoning was also evident in subdued light.     

Evaluation of the protective efficacy of Asteracantha longifolia on acetaminophen-induced liver damage in rats

The effect of oral administration of methanolic extract of Asteracantha longifolia (AL) seeds on acetaminophen (APAP)-induced acute liver damage in rats was investigated. The activities of marker enzymes (aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma glutamyl transferase) and bilirubin level in serum and the levels of cholesterol, triglycerides, and free fatty acids in both serum and liver were found to be increased when rats were challenged with APAP. This was also associated with a significant reduction of serum and tissue phospholipids. Pretreatment with AL extract prior to the administration of APAP prevented these alterations as evidenced by liver histopathology. Results indicated that the extract could offer protection against APAP-induced liver damage, suggesting its hepatoprotective activity.     

Effect of Atrazine on Growth, Photosynthesis, and Between-Strain Variability in Scenedesmus subspicatus (Chlorophyceae)

The magnitude of between-strain differences in the sensitivity of algal species to toxicants is not well known. Yet, informations obtained with a single strain are used for ecotoxicological assessment and for interspecific comparisons. Using 12 strains, we determined whether intraspecific variability occurs in the green alga Scenedesmus subspicatus. We examined growth, photosynthetic activity, and short-term sensitivity thereof to the herbicide atrazine (500 μg · L⁻¹) as well as how these responses are affected by chronic exposure to low atrazine concentrations (0, 1, 5, and 20 μg · L⁻¹). Independent of chronic exposure to atrazine, the strains differed in growth rate and photosynthesis rate. Yet the short-term sensitivity to atrazine was affected by the chronic treatments. All but one strain became more tolerant, their short-term sensitivity being inversely related to the applied atrazine concentration and dependent on the duration of exposure. Differences in response to increments in atrazine concentration resulted in differences in rank order of sensitivity of strains. Moreover, between-strain variability was markedly higher in the atrazine treatments than in the controls. These results can be explained by the significant role of genotype versus environment interactions in determining intraspecific differences in adaptive physiological responses of S. subspicatus to chronic exposure to atrazine. Received: 2 February 1998/Accepted: 26 January 1999     

Effects of nonylphenol on cholinesterase and carboxylesterase activities in male guppies (Poecilia reticulata)

Compared to the estrogenic effects of 4-nonylphenol (NP), there is little data available on other potential toxic effects of NP in aquatic animals. The effects of NP on cholinesterase (ChE) and carboxylesterase (CbE) activities of male guppies exposed to 10, 60, 150, or 300 μg L⁻¹ NP were examined after 1, 2, 4, and 7 days of treatment. A significant muscle ChE inhibition, that used acetylthiocholine iodide as a substrate, was noted in male guppies in all NP treatment groups after a 4-day exposure, and 60 and 150 μg L⁻¹ of NP treatment groups after a 7-day exposure. All guppies exposed to 300 μg L⁻¹ NP died during the 7-day treatment. However, there was no significant inhibition of muscle ChE that used butyrylthiocholine iodide as a substrate in male guppies for any NP treatments in different exposure times. There were no CbE activity differences in livers of male guppies among NP treatment groups after different exposure times. This is the first report showing the ChE activity inhibition by NP in fish. Further mechanistic studies are needed to define how NP directly or indirectly alters ChE activities at molecular level. The implication of ChE inhibition of NP on potential impacts of aquatic animals also warrants further research.     

The effect of stinging nettle (Urtica dioica) seed oil on experimental colitis in rats

This study investigated the effect of Urtica dioica, known as stinging nettle, seed oil (UDO) treatment on colonic tissue and blood parameters of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. Experimental colitis was induced with 1 mL of TNBS in 40% ethanol by intracolonic administration with a 8-cm-long cannula with rats under ether anesthesia, assigned to a colitis group and a colitis+UDO group. Rats in the control group were given saline at the same volume by intracolonic administration. UDO (2.5 mL/kg) was given to the colitis+UDO group by oral administration throughout a 3-day interval, 5 minutes later than colitis induction. Saline (2.5 mL/kg) was given to the control and colitis groups at the same volume by oral administration. At the end of the experiment macroscopic lesions were scored, and the degree of oxidant damage was evaluated by colonic total protein, sialic acid, malondialdehyde (MDA), and glutathione levels, collagen content, tissue factor activity, and superoxide dismutase and myeloperoxidase activities. Colonic tissues were also examined by histological and cytological analysis. Pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-1β, and interleukin-6), lactate dehydrogenase activity, and triglyceride and cholesterol levels were analyzed in blood samples. We found that UDO decreased levels of pro-inflammatory cytokines, lactate dehydrogenase, triglyceride, and cholesterol, which were increased in colitis. UDO administration ameliorated the TNBS-induced disturbances in colonic tissue except for MDA. In conclusion, UDO, through its anti-inflammatory and antioxidant actions, merits consideration as a potential agent in ameliorating colonic inflammation.     

Metal accumulation in a biological indicator (Ulva rigida) from the lagoon of Venice (Italy)

Ulva rigida (C. Agardht) was collected from the Palude della Rosa (lagoon of Venice), a particular area characterized by a salinity gradient, from December 1991 to June 1993. Metal contents (Al, Mn, Fe, Cu, Zn, Cr, Co, Ni, Cd, and Pb) were determined by atomic absorption spectrophotometry and statistically analysed for differences between months and sampling sites. The mean seasonal variability is very significant (p<0.001) for all studied metals. Seasonal trends are comparable for groups of metals according to possible functional similarities. A significant positive correlation was calculated for the pairs Fe-Al and Fe-Pb. Mechanisms regulating metal uptake are discussed, particularly the role of Fe and its linear relationship with Al. Metal concentrations in relation to salinity also were studied. Larger amounts of Fe, Zn, and Cd accumulated in correspondence of lower salinity, may be owing to both higher metal activity and burden of bioavailable metals in freshwater flowing into the Palude. Calculation of concentration factor (CF) indicates that U. rigida specifically accumulates Fe. CF linearly correlates with dissolved metal concentrations, suggesting that U. rigida is a good bioindicator of metal bioavailability, although seasonal active accumulation occurs in some cases (Mn). Metal concentrations determined in this macroalga support the conclusion that the studied area is rich in bioavailable Fe and poor in toxic metals. In any case, a great affinity for Al in U. rigida may be proposed.     

Maitake (Grifola frondosa) improve glucose tolerance of experimental diabetic rats

We have previously reported that rats with diabetes induced by injecting streptozotocin into neonates showed remarkably lower blood glucose, urine volume, and glucosuria after administration of Maitake (Grifola frondosa). In the present study, we investigated the effects of Maitake on insulin concentration, organ weight, serum composition, and islets of Langerhans in streptozotocin-induced diabetic rats using the same method. The diabetic rats were produced by injecting 80 mg/kg B.W. streptozotocin into 2-d-old neonates. From the age of 9 wk, the rats were given experimental diets for 100 d. The diabetes and control groups were given either diets containing 20% Maitake (DM and CM groups) or control diets (D and C groups). During administration of the experimental diets, we measured body weight, food intake, amount of feces, and serum insulin concentration at glucose loading. The glucose tolerance test was performed at the 10th week after the start of the experimental diets. The D group had an initial fasting blood glucose of 225+/-49 mg/dL, and a maximum blood glucose of 419+/-55 mg/dL at 60 min. In the DM group, however, the initial fasting blood glucose was 170+/-23 mg/dL, and the maximum blood glucose was 250+/-41 mg/dL at 15 min. Both values were markedly lower than those in the D group (p<0.05). The insulin concentration at 15 min. after glucose loading in the DM group was 41+/-16 microU/mL, which was significantly higher than that in the D group (15+/-7 microU/mL) (p<0.05). After the 100-d experimental period, blood samples were collected. The fructosamine level was significantly lower in the DM group (152+/-21 mmol/L) than in the D group (185+/-13 mmol/L). The concentration of 1.5-A.G. (1.5-anhydro glucitol) was significantly higher in the DM group (9.33+/-2.42 microg/mL) than in the D group (1.33+/-0.52 microg/mL). Observation of insulin antibody stain in the Langerhans cells of the pancreas using ABC method showed a decrease insulin antibody stain in the D group. The cells of the DM group were stained more darkly than those of the D group. From these results, we postulated that the bioactive substances present in Maitake can ameliorate the symptoms of diabetes.     

Extractable substances (anionic surfactants) from membrane filters induce morphological changes in the green alga Scenedesmus obliquus (Chlorophyceae)

The effect of filtration of medium through different kinds of filters (glass fiber, mixed esters of cellulose and nitrocellulose) on the morphology in the green alga Scenedesmus obliquus was examined. Several compounds potentially released from membrane filters were further investigated, and among them, two anionic surfactants were found to be morphologically active. Exposure to the anionic surfactants resulted within 2 d in the transformation of unicellular populations of Scenedesmus in populations dominated by colonies. Growth rates between control and surfactant-exposed populations were identical, and the morphological effect occurred at surfactant concentrations far below the reported no-observed-effect concentration for growth inhibition, stressing the need for inclusion of morphological appearance of Scenedesmus in algal toxicity testing to improve the assessment of ecological risks.     

Metal Content in Ulva lactuca (Linnaeus) from Navachiste Bay (Southeast Gulf of California) Sinaloa, Mexico

No abstract available.     

碘对自身免疫性甲状腺炎大鼠抗氧化能力影响

目的 探讨不同碘水平对实验性自身免疫甲状腺炎(experimental autoimmune thyroiditis,EAT)大鼠抗氧化活性的影响。方法 选择雌性Lewis大鼠,随机分为4组;于实验第8周处死动物,观察大鼠甲状腺组织的病理变化,测定甲状腺球蛋白抗体(TGAb)、甲状组甲状腺腺微粒体抗体(TMAb),肝和脑组织中谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活性。结果 各造模组织出现淋巴细胞浸润,高碘时以甲状腺滤泡扩张、融合为主,低碘时以增生为主;高碘+造模组大鼠的TGAb和TMAb水平分别为(75.00±15.44)%,(72.15±15.00)%,明显高于造模组的(63.01±12.36)%,(60.62±11.24)%和低碘+造模组的(58.87±9.57)%,(57.89±9.67)%(P<0.05);低碘组EAT大鼠肝组织GSH-Px和SOD活性最低,分别为(122.01±10.34),(522.81±54.62)U/(mg.prot)(P<0.05)碘过量时脑组织谷胱甘肽过氧化物酶(GPX)活性最低,为(412.09±115.71)U/(mg.prot)(P<0.05)。结论 碘缺乏和碘过量均能够加重EAT大鼠甲状腺的炎性损伤和氧化损伤,其中碘缺乏对EAT大鼠作用明显。     

Toxicokinetics and toxicity of zinc under time-varying exposure in the guppy (Poecilia reticulata)

Levels of toxic substances released into the environment are often highly variable and fluctuate over time. The present study deals with a simple type of time-variable exposure, diluted pulse. We determined toxicokinetic parameters of zinc in guppy fish (Poecilia reticulata) and evaluated the applicability of a toxicokinetics-based survival model developed earlier. In the toxicokinetics experiment, zinc was rapidly taken up and released again; the half-life in fish was only 1.5 d. In the toxicity experiments with diluted-pulse exposure, survival leveled off to a baseline level, which in accordance with the model is explained by the dilution of zinc. The model fitted reasonably well for the lower initial concentrations but tended to overestimate survival rates at the higher concentrations. Toxicokinetic parameters estimated from changes in survival were close to values estimated from measured zinc concentrations in water. Elimination rates during pulse exposure varied from 0.434 to 0.488 d(-1) and corresponded very well to the elimination rate during constant exposure (0.463 d(-1)). Ultimate LC50 values were estimated as 6.40 and 9.10 mg/L. These results suggest that toxicity experiments with a simple, time-varying exposure can be used as an alternative to conventional, constant-exposure experiments. Toxicokinetic parameters and toxicological endpoints can still be estimated in static bioassays with decreasing exposure if the concentration in the medium is measured. At the same time, diluted-pulse experiments may simulate exposure from discharges in the field better than constant-exposure experiments.     

Factors affecting the absorption of phenolics and carboxylic acids in the guppy (Poecilia reticulata)

The rate of absorption of 17 phenols, anisoles, and carboxylic acids in the guppy (Poecilia reticulata Peters) was measured at pH levels from 3 to 9. The rate was directly proportional to the concentration, and the compounds did not interfere with each other's absorption. The primary route of uptake was across the gill epithelium, but 25-40% of the total amount penetrated across the skin. When the fish were exposed at a pH low enough to prevent ionization of acidic compounds, the initial rate of uptake increased with lipophilicity up to a partition coefficient of about 10(4). Above this point, the absorption rate did not correlate with lipophilicity indicating that the uptake rate of the most lipophilic compounds was limited by the unstirred water layers. The effect of lipophilicity on absorption accounts for about half of the effect found in toxicity and bioconcentration. The absorption rate of acids declined with pH rising, but did not follow changes in the concentration of nonionized acid. The slopes of the absorption rate vs pH curves were distinctly less steep than the slope of the dissociation curve. In addition, the curves of the most lipophilic acids showed a shift to the right, which can be ascribed to the unstirred layers on the surface of the epithelia.     

Assessment of the alkaline (ALP) and acid phosphatase (ACP) in the blood serum of rats during experimental postmenopausal osteoporosis

The aim of this study was to evaluate the activity of alkaline (ALP) and acid (ACP) phosphatase in the blood serum of rats after ovariectomy and with estrogen replacement therapy. The relationship between mandible and spine bone mineral density (BMD) and parameters of bone remodeling was also estimated. The concentration of serum total alkaline and acid phosphatase was higher in the rats with estrogen deficiency, and statistically lower in rats administering 17 beta-estradiol. ALP and ACP levels were correlated significantly negative with mandible and spine BMD. Carried out examinations confirmed increasing bone resorption during experimental postmenopausal osteoporosis.