Acute toxicity and bioaccumulation of endosulfan in rotifer (Brachionus calyciflorus).

1. The acute toxicity of endosulfan was determined for the freshwater rotifer Brachionus calyciflorus. 2. The mean 24 hr LC50 value for endosulfan was 5.15 ppm with a coefficient of variation of 14.7%. 3. Rotifers were exposed at two sublethal concentrations (1.5-2.0 ppm) of endosulfan for bioaccumulation experiments, for an exposure time of 24, 48, 72 and 96 hr. The rotifers were fed with Nannochloris oculata (5 x 10(5) cell/ml). 4. The highest accumulation of endosulfan was found 24 hr after the start of the exposure to 1.5 ppm of the toxicant. A steady-state concentration in rotifer was reached between 24-48 hr, followed by a gradual decrease until 96 hr.     

Short-term effects of mercury on survival, behaviour, bioaccumulation and ionic pattern in the catfish (Clarias lazera)

1. The fresh-water fish, Clarias lazera, was exposed to 13 lethal and sublethal concentrations of mercury. 2. The median tolerance limit (TLm) at different exposure periods, 24, 48, 72 and 96 hr, appears to be as follows: 0.96, 0.88, 0.81 and 0.72 ppm Hg2+/l, respectively. 3. From the subacute tests, the maximum acceptable toxicant concentration (MATC) for this fish was between 0.10 and 0.22 ppm Hg2+/l. 4. Behavioural changes, tissue Hg2+ distribution and serum ionic patterns were recorded during both the acute and subacute exposure periods.     

Changes in tissue adenylates and water content of bluegill, Lepomis macrochirus, exposed to copper

Bluegill were exposed to copper (2–0 mg/1⁻¹ unfiltered) for 24, 48, 72 or 96 h at 24° C. This concentration approximated the 96 h LC20. Water content of liver increased 4–8% after 24 h exposure and muscle 4–6% by 48 h. These changes persisted throughout the 96 h experiments. Copper exposed fish exhibited decreases in muscle ATP, ADP, total adenylates, and energy charge by 48 h. There was a trend toward recovery of ATP with further exposure. Liver ATP of exposed fish was lower than controls at all intervals with the greatest difference evident at 48 h. No significant changes in brain adenylates were observed. Muscle and liver lactic acid was unchanged at 48 h exposure, therefore tissue hypoxia was not the cause of the adenylate changes. It was concluded that copper causes decreases in muscle and liver ATP several days before probable death of copper exposed fish and the changes seen are the result of dilution by increased tissue water, and the copper acting on certain cellular enzymes involved in detoxification and energy metabolism.     

Toxicity, repellency, and transfer of chlorfenapyr against western subterranean termites (Isoptera: Rhinotermitidae)

Chlorfenapyr is a slow-acting insecticide against western subterranean termite, Reticulitermes hesperus Banks, when applied to sand. The LD50 at day 7 for workers is 29.98 ng per termite and considerably higher than that of chlorpyrifos (14.01), cypermethrin (3.21), and fipronil (0.16). Brief exposures to sand treated with chlorfenapyr resulted in dose-dependent mortality over a broad range of concentrations. Brief 1-h exposures to > or =75 ppm provided >88% kill of termites at day 7. Chlorfenapyr deposits did not repel termites, even at 300 ppm. Termites tunneled from 0.1 to 1.8 cm into sand treated with 10- to 300-ppm chlorfenapyr deposits, resulting in > or =70% mortality. Within 1 h after being exposed to 50 ppm chlorfenapyr, approximately 17% of the termites exhibited impaired responses to synthetic trail pheromone. By 4 h, nearly 60% of the workers were not able to follow a 10 fg/cm pheromone trail. There was a direct linear relationship of the uptake of [14C]chlorfenapyr as concentration and duration of exposure increased. The percentage of chlorfenapyr transferred to recipients varied from 13.3 to 38.4%. Donors exposed for 1 h transferred a greater percentage of chlorfenapyr than did donors exposed for 4 h. A 1-h exposure on 100-ppm deposits provided sufficient uptake to kill 100% of the donors and sufficient transfer to kill 96% of the recipients. There was not enough transfer for recipients to serve as secondary donors and kill other termites. Horizontal transfer is limited to contact with the original donor and by the decreased mobility of workers within 4-8 h after exposure to treated sand. The effectiveness of chlorfenapyr barrier treatments is primarily due to its nonrepellency and delayed toxicity.     

Acute severe carbon monoxide exposure in the rat: effects of hyperglycemia and hypoglycemia on mortality, recovery, and neurologic deficit.

Human and animal studies suggest a poorer outcome in the presence of abnormal blood glucose concentration during cerebral hypoxia-ischemia. It is unknown whether this is also the case in acute severe carbon monoxide poisoning. Using Levine-prepared rats, three groups were established and exposed to CO to answer this question: (1) hyperglycemics resulting from the administration of a 50% glucose solution, (2) hypoglycemics resulting from the administration of normal saline, and (3) untreated controls. The rats inhaled 2400 ppm CO for 90 min in the absence of anesthesia. Blood glucose was raised to a mean value of 402 mg/dL just prior to CO exposure in group 1. This resulted in an increased mortality rate (i.e., 54%), and during 4 h of room air recovery an impaired ability to regain body temperature, an increased plasma lactate dehydrogenase activity, and an increased neurologic deficit as compared with group 3. Hypoglycemia, which developed during CO exposure in group 2 (mean minimum glucose after 90 min, 44 mg/dL), resulted in an increased mortality rate (i.e., 46%), and during 4 h of room air recovery an impaired ability to regain body temperature and an increased neurologic deficit as compared with group 3. Blood glucose concentration in the rats in groups 2 and 3 that died during or shortly after CO exposure was significantly depressed relative to the survivors of those groups. Plasma insulin activity was elevated during CO exposure in group 1 as compared with group 3, but fell during recovery; insulin remained low throughout CO exposure and recovery in group 2. The results demonstrate the deleterious effects of both a very high and a very low blood glucose concentration during acute CO exposure.     

Effects of copper and other metals on fertilization,embryo development,larval survival and settlement of the polychaete Nereis (Neanthes) virens

Summary

Nectochaete larvae of the ecologically and economically important ragworm, Nereis virens, were exposed to cadmium, chromium, copper, lead and zinc dissolved in seawater to nominal concentrations ranging from 0 to 5000 μg l^?1. Copper was the most toxic (mean LC50 of 76.5 μg l^?1 ± 95% CI 73.8–79.2 after 96 h exposure) and so was used for subsequent experiments. Exposure of gametes to greater than 500 μg l^?1 copper for 2 or 4 h at 10°C prior to fertilization, or a 10 min exposure during fertilization, significantly reduced embryo developmental success. The effect of copper on larval settlement was also assessed using sediment spiked to a range of concentrations (0, 50, 250, 500, 1000 mg kg!1 dry weight). Significantly fewer larvae were found in sediment of $250 mg kg!1 in comparison to the control or the 50 mg kg!1 treatment. Assessment of living larvae also confirmed a significant reduction in settlement, but in all treatments compared to the control, although the number of dead larvae also increased as the concentrations increased. These effects may have important implications for reproductive success and recruitment of N. virens to polluted sediments.     

The distribution of zinc and copper in plasma, erythrocytes and erythrocyte membranes of rainbow trout (Salmo gairdneri)

1. The zinc and copper concentration of plasma was determined in rainbow trout, lake trout, walleye and whitefish. 2. These fish had mean plasma zinc concentrations ranging from 9.3 to 15.1 ppm and copper concentrations from 0.6 to 1.3 ppm. 3. In rainbow trout, the concentration of zinc and copper is greater in the erythrocyte membrane than in the total erythrocyte. 4. Ultrafilterable plasma zinc and copper concentration in rainbow trout was determined to be 0.03 and 0.019 ppm, respectively. 5. Dialysis of rainbow trout plasma against 20 mM EDTA results in removal of 99% of the zinc and 88% of the copper from plasma proteins.     

Impact of copper application on soil metabolism,energy budget and formation of stable aggregates by anecic earthworm in tea plantations

The preparation of daily energy budget of earth worm Lampito mauritii showed (i) decrease in consumption by about 66%, (ii) decrease of egestion 97%, (iii) decrease in growth by 80%, and (iv) enhancement in maintenance cost by about 31.5% on exposure to 8 ppm copper in comparison to zero level exposure. The stable aggregate formations also decreased by 67.6% at 8 ppm copper as compared to zero level exposure. Two way ANOVA showed significant decrease in stable aggregate formation and biomass at 5% level of significance on exposure to 8 ppm copper. The soil metabolism also increased under the negative impact of copper.     

Lead acetate: toxicity without effcts on the locomotor activity of the bluegill sunfish, Lepomis macrochirus Rafinesque

The concentration of lead acetate which caused 50% mortality of bluegill in 96 h (96 h LC50) is approximately 400 ppm. Sublethal concentrations of 0.1, 1, 10, 100, 200 and 300 ppm lead acetate did not produce any effects on the locpmotor activity of the bluegill. The observation that lead can reach concentrations which are lethal without sublethal effects on locomotor activity at lower concentrations is unusual and in sharp contrast to studies with other metals (Ellgaard et al. . 1978).     

二氧化硫剂量与植物急性伤害关系

应用大气污染植物动态反应模拟装置系统测定了菜豆和苜蓿的SO_2剂量-反应关系。这2种植物对SO_2有类似的敏感性,0.5ppmSO_2×4小时产生可见伤害症状。苜蓿在2.0ppm×4小时出现50％的叶片可见伤害;菜豆在1.0ppm×8小时显示出50％的叶片可见伤害,2.0ppmSO_2×12小时引起100％的叶片可见伤害。 剂量-反应表面图的形状表明,菜豆和苜蓿出现可见伤害症状需要一定的暴露间隔。SO_2剂量和可见伤害率之间不成线性关系。SO_2浓度和暴露时间对叶片可见伤害率都有影响,两者相比,就菜豆而言,浓度是更重要的因素,但是对苜蓿,浓度和时间是同等重要的。     

Effects of copper on phagocytosis inTetrahymena

Summary Addition of copper, corresponding to 100 ppm, to the normal 2% proteose peptone medium is tolerated byTetrahymena. This concentration of copper stimulates phagocytosis to a maximum value which is reached gradually during the first 1 hour exposure, and which is maintained during continuous exposures. Cell proliferation is resumed after a lag period, although at a decreased rate. Cells exposed to copper contain small refractile granules, previously proposed to represent an ion-regulating system; the number of granules remains constant in proliferating cells. Higher concentrations of copper also resulted in an elevated rate of phagocytosis but at the same time cell mortality was observed; this lack of transition between inhibited phagocytosis and cell mortality may be ascribed to the physiological role of copper. The high amount of organic matter in the growth medium protects against the toxic effects of copper, thus in the absence of organic matterTetrahymena tolerated only a 100-fold lower concentration of copper than that tolerated in the growth medium. However, cells which had initiated granule formation (for example for regulation of calcium) prior to starvation and exposure to copper, were more resistant to copper than cells which had not yet activated this mechanism, perhaps because of the low capacity of starved cells for protein synthesis.     

Copper nanoparticles: Green synthesis and managing fruit rot disease of chilli caused by Colletotrichum capsici

The present study was focused on synthesis and characterization of copper nanoparticles to evaluate their efficacy against fruit rot pathogen of chilli crop. The green synthesis of nanoparticles was carried out by using extracts of Eucalyptus and Mint leaves. The synthesis of copper nanoparticles was confirmed by XRD, PSA, SEM and TEM. The average size of these particles synthesized by Eucalyptus leaf extract (CuNP-E) ranged from 10 to 130 nm, while as size of Mint leaf extract synthesized particles (CuNP-M) ranged from 23 to 39 nm, thus confirming their nano size. These green synthesized copper nanoparticles were evaluated against Colletotrichum capsici where Carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm served as standard checks. The mycelia inhibition of Colletotrichum capsici caused by copper nanoparticles was studied on PDA medium. CuNP-M @ 1000 ppm showed highest mycelial inhibition of 99.78% followed by 93.75% at 500 ppm and CuNP-E @ 1000 ppm compared to standard fungicides, carbendazim 50 WP @ 500 ppm (72.82%), and copper oxychloride 50 WP @ 2500 ppm (85.85%). The CuNP-M @ 500 ppm were significantly superior to carbendazim 50 WP @ 500 ppm and copper oxychloride 50 WP @ 2500 ppm, but was statistically at par with CuNP-E @ 1000 ppm. This shows effectiveness of much lower concentration of copper nanoparticles compared to conventional fungicides. In detached fruit method, nanoparticles applied before inoculation of pathogen showed better results with regard to incubation period, lesion number and lesion size than after inoculation of pathogen. The present study reveals a simple, convenient, non-toxic and cost-efficient technique for the synthesis of nanoparticles and their effectiveness against Colletotrichum capsici. CuNP-M first time synthesized and evaluated against Colletotrichum capsici performed better than CuNP-E.     

Changes in Proline Content Accompanying the Uptake of Zinc and Copper by Lemna minor

Lemna minor L. grown in Hoagland solution containing zinc (10ppm) or copper (5 ppm) for 4 d accumulated high levels of thesemetals. Zinc and Cu accumulation in the test plants was accompaniedby a specific pattern of change in proline content. The lattershowed a steep rise during early stages (peak at 12-24 h) followedby a gradual decline until 96 h of treatment. In a dose-responsestudy, lower metal concentrations induced a sharp rise in prolinelevel with a maximum value at 5 ppm, which declined when theconcentration was further enhanced. There was a correspondencebetween the level of proline and total free amino acids in metaltreated plants. The possibility of proline involvement in tolerancemechanisms to heavy metals has been discussed.Copyright 1993,1999 Academic Press Heavy metals, zinc, copper, proline, total free amino acids, Lemna minor     

Copper kinetics and hepatic metallothionein levels in the frog Rana ridibunda, after exposure to CuCl2

Adult female frogs Rana ridibunda were exposed to 50 and 100 ppm of Cu (as CuCl₂) dissolved in water for 5, 15 and 30 days. We measured the Cu content in the liver, kidneys, ventral skin, and large intestine. Hepatic metallothionein (MT) was also measured and we identified by elution the type of proteins bound to copper. Gross morphological characteristics of the frogs were not affected by Cu accumulation. Cu uptake took place first across the skin, then accumulated first in the large intestine, and then in the liver which was continuously accumulating Cu at all exposure concentrations and times. The highest concentration of the metal was recorded in the kidneys at 30 days and 100 ppm exposure. It appears that the kidneys act as the secondary route of Cu detoxification, probably after a Cu overload of liver. The concentration of hepatic MT increased with the increase of Cu concentration in liver at the 5^th and 15^th day of exposure but we observed a decrease by the end of the experiment. Cu was observed in the MT-fraction, and in the high-molecular weight protein fraction.     

Acclimatable cardiac and ventilatory responses to copper in the freshwater crayfish Procambarus clarkii

Mortality and physiological tests following exposure to waterborne copper were performed in the red swamp crayfish Procambarus clarkii from a central Italian population. Mortality tests gave an estimated 96 h LC50 value (with 95% confidence limits) of 162 (132-211) mg L(-1) waterborne copper II. Variations in cardiac and ventilatory rates were simultaneously monitored using a non-invasive plethysmographic technique. In experiments with different sub-lethal copper concentrations (control, 0.5, 1 and 10 mg L(-1)) performed at different times (3, 6, 96 h), copper exposure elicited a reduction in both heart and scaphognatite rates. Following exposure to 10 mg L(-1) copper for 96 h, the heart and scaphognatite rates decreased to about 35% of the initial values. The reduction was fully reversible, since crayfish exposed to 0.5, 1 and 10 mg Cu L(-1) for 96 h resumed control rates after a 3-h residence in clean water. In crayfish pre-exposed (96 h) to sub-lethal copper concentrations (0.1 and 1 mg L(-1)) and then held in control water (3 h), the reduction of heart and scaphognatite rates after exposure to 10 mg Cu L(-1) were significantly lower than in specimens pre-exposed to control water. Therefore, copper induces a concentration and time dependent reduction of both cardiac and ventilatory activity in P. clarkii; these responses can be reduced or fully abolished by pre-exposure to sub-lethal levels of the metal.     

The temperature dependence of the acute toxicity of copper to a freshwater pond snail,Viviparus bengalensis L.

Static bioassays with copper (as CuSO₄ · 5H₂O) were conducted in laboratory with a freshwater pond snailViviparus bengalensis, at different environmental temperatures. The 96 hr LC50 values in ppm of Cu were 0.060 at 32.5 °C; 0.066 at 24 °C; 0.09 at 27.3 °C and 0.39 at 20.3 °C. In higher copper concentrations some behavioural changes such as secretion of mucus, discharge of eggs and embryos were noted. The results indicate that toxicity to copper increases with temperature increase.     

The effect of time on physiological changes in eel Anguilla anguilla, induced by lindane.

1. Eel were exposed to a sublethal concentration of lindane (0.335 ppm) for 6, 12, 24, 48, 72 and 96 hr. 2. Concentrations of glycogen, glucose, lactate, pyruvate and lipids were determined in gill tissue after lindane exposure. 3. Gill glycogen decreased and glucose levels increased at 6 hr of treatment, lactate and pyruvate concentration increased between 6 and 48 hr. Total lipid values decreased between 6 and 24 hr; thereafter, the levels increased up to 72 hr of exposure. 4. Clear changes were found in all parameters tested in gill tissues. The observed effects of lindane on metabolism in fish are discussed in relation to acute stress syndrome.     

Reversal of Cadmium-Induced Thyroid Dysfunction by Selenium, Zinc, or Their Combination in Rat

The aim of this study was to evaluate the potential benefit of combined treatment with zinc (Zn) and selenium (Se) in reversing cadmium (Cd)-induced thyroid dysfunction compared to Se or Zn treatment alone in rats exposed to Cd. For this purpose, 30 adult male Wistar albino rats were equally divided into control and four treated groups receiving either 200 ppm Cd (as CdCl2), 200 ppm Cd + 500 ppm Zn (as ZnCl2), 200 ppm Cd + 0.1 ppm Se (as Na2SeO3), or 200 ppm Cd + 500 ppm Zn + 0.1 ppm Se in their drinking water for 35 days. The results showed that Cd exposure increased significantly the relative thyroid weight (RTW), the thyroid Cd concentration, and the serum thyroid stimulating hormone (TSH) level, whereas the serum thyroxine (T4) level was decreased compared to control rats. The treatment of Cd-exposed rats with Se alone only partially protected from the Cd-induced decrease in serum T4 level. The treatment of Cd-exposed animals with Zn alone partially protected against Cd-induced thyroid dysfunction by maintaining normal RTW and by decreasing Cd concentration in the thyroid. It also partially prevents Cd-induced decrease in serum T4 level. The combined treatment of Cd-exposed animals with Se and Zn induced a more significant decrease in the thyroid Cd concentration than the Zn supplement and a total correction of the RTW. This treatment was also more effective than that with Se or Zn alone in reversing Cd-induced decrease in serum T4 level and Cd-induced increase in serum TSH level. Se and Zn can have a synergistic role against Cd-induced thyroid dysfunction.     

Developmental toxicity studies in Crl:CD (SD) rats following inhalation exposure to trichloroethylene and perchloroethylene

The potential for trichloroethylene (TCE) and perchloroethylene (PERC) to induce developmental toxicity was investigated in Crl:CD (SD) rats whole-body exposed to target concentrations of 0, 50, 150 or 600 ppm TCE or 0, 75, 250 or 600 ppm PERC for six hours/day, seven days/week on gestation day (GD) 6-20 and 6-19, respectively. Actual chamber concentrations were essentially identical to target with the exception of the low PERC exposure level, which was 65 ppm. The highest exposure levels exceeded the limit concentration (2 mg/L) specified in the applicable test guidelines. Maternal necropsies were performed the day following the last exposure. Dams exposed to 600 ppm TCE exhibited maternal toxicity, as evidenced by decreased body weight gain (22% less than control) during GD 6-9. There were no maternal effects at 50 or 150 ppm TCE and no indications of developmental toxicity (including heart defects or other terata) at any exposure level tested. Therefore, the TCE NOEC for maternal toxicity was 150 ppm, whereas the embryo/fetal NOEC was 600 ppm. Maternal responses to PERC were limited to slight, but statistically significant reductions in body weight gain and feed consumption during the first 3 days of exposure to 600 ppm, resulting in a maternal NOEC of 250 ppm. Developmental effects at 600 ppm consisted of reduced gravid uterus, placental and fetal body weights, and decreased ossification of thoracic vertebral centra. Developmental effects at 250 ppm were of minimal toxicological significance, being limited to minor decreases in fetal and placental weight. There were no developmental effects at 65 ppm.     

Effects of addition of varying levels of copper,as oxide or phosphate,on nitrogen mineralisation and nitrification during incubation of a slightly calcareous soil receiving dried blood

Summary The addition of 100, 1000 and 10,000 ppm copper, as oxide or hydrogen phosphate, stimulated nitrogen mineralisation and nitrification during incubation of a sandy loam (0.5% calcium carbonate) treated with 200 ppm N as dried blood. The maximum effects occurred with 1000 ppm added copper and were similar with both sources of added copper. EDTA-extractable copper was higher where copper hydrogen phosphate than where copper oxide had been added.