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Min Exposure Period (min + exposure_period)
Selected AbstractsToxicity assessment of reference and natural freshwater sediments with the LuminoTox assayENVIRONMENTAL TOXICOLOGY, Issue 4 2006P. M. Dellamatrice Abstract We examined the possibility of adapting the LuminoTox, a recently-commercialized bioanalytical testing procedure initially developed for aqueous samples, to assess the toxic potential of sediments. This portable fluorescent biosensor uses photosynthetic enzyme complexes (PECs) to rapidly measure photosynthetic efficiency. LuminoTox testing of 14 CRM (Certified Reference Material) sediments was first undertaken with (1) a "solid phase assay" (Lum-SPA) in which PECs are in intimate contact with sediment slurries for a 15 min exposure period and (2) an elutriate assay (Lum-ELU) in which PECs are exposed for 15 min to sediment water elutriates. CRM sediment toxicity data were then compared with those generated with the Microtox Solid Phase Assay (Mic-SPA). A significant correlation (P < 0.05) was shown to exist between Lum-SPA and Mic-SPA, indicating that both tests display a similar toxicity response pattern for CRM sediments having differing contaminant profiles. The sediment elutriate Lum-ELU assay displayed toxicity responses (i.e. measurable IC20s) for eight of the 14 CRM sediments, suggesting that it is capable of determining the presence of sediment contaminants that are readily soluble in an aqueous elutriate. Lum-SPA and Mic-SPA bioassays were further conducted on 12 natural freshwater sediments and their toxicity responses were more weakly, yet significantly, correlated. Finally, Lum-SPA testing undertaken with increasing mixtures of kaolin clay confirmed that its toxicity responses, in a manner similar to those reported for the Mic-SPA assay, are also subject to the influence of grain size. While further studies will be required to more fully understand the relationship between Lum-SPA assay responses and the physicochemical makeup of sediments (e.g., grain size, combined presence of natural and anthropogenic contaminants), these preliminary results suggest that LuminoTox testing could be a useful screen to assess the toxic potential of solid media. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 395,402, 2006. [source] The effect of different kinds of electrolyte and non-electrolyte solutions on the survival rate and morphology of zebrafish Danio rerio embryosJOURNAL OF FISH BIOLOGY, Issue 7 2009F. Lahnsteiner The effect of electrolyte and non-electrolyte solutions on the survival and on the morphology of zebrafish Danio rerio embryos was investigated. Embryos in different ontogenetic stages were incubated in electrolyte (NaCl, KCl, MgCl2 and CaCl2) and non-electrolyte solutions [sucrose and polyvinylalcohol (PVA)] of different concentrations for 5 , 15 min. The embryos were hatched to the long-pec stage and the effective concentrations which caused a 50% decrease in embryo development (EC50) were determined. The morphometric changes, which were caused by the test solutions, were measured. Ion channel blockers were used to see if active ion transport played a role for embryo survival. Finally, dechorionated embryos were exposed to the test solutions to get indications about the importance of chorion and perivitelline space. For 12 hours post fertilization (hpf) embryos and a 15 min exposure period, EC50 was highest for MgCl2 (1·60 mol l,1), followed by sucrose (0·73 mol l,1), NaCl (0·49 mol l,1), KCl (0·44 mol l,1), CaCl2 (0·43 mol l,1) and PVA [0·0005 mol l,1 (2·2%)]. EC50 were lower for early embryonic stages than for advanced stages for all solutions with exception of MgCl2 and sucrose. At the EC50, MgCl2 and CaCl2 solutions did not induce morphometric changes. NaCl and sucrose solutions induced reversible morphometric changes, which were compensated within 10 min. Only the EC50 of KCl and PVA solutions induced permanent morphometric changes, which could not be compensated. Incubation of embryos in electrolyte and non-electrolyte solutions together with ouabain (blocker of Na+, K+ ATPase), HgCl3 (dose-dependent inhibition of aquaporine channels), verapamil (inhibition of calcium and magnesium uptake) and amiloride (inhibition of sodium uptake) significantly decreased the per cent of embryos developing to the long-pec stage in comparison to the same solutions without blockers. Ouabain and HgCl3 also induced morphometric changes. For dechorionated embryos the survival rates in water and in the different test solutions were similar to untreated embryos. [source] The Application of Hydrogen Peroxide as a Treatment for the Ectoparasite Amyloodinium ocellatum (Brown 1931) on the Pacific Threadfin Polydactylus sexfilisJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2001Dee Montgomery-Brock Ectoparasite infections can cause death or a decline in the general health of farm-raised finfish. This paper reports the findings from two studies conducted to evaluate the efficacy of hydrogen peroxide as a therapeu-tant for the control of infections of Amyloodinium sp. on cultured Pacific threadfin Polydactylus sexfilis (locally called "moi"). Threadfin with amyloodiniasis collected from a commercial farm were used in both trials. Prior to the trials, and following hydrogen peroxide treatment, the extent of infection was determined by a gill biopsy procedure. An initial trial was conducted in the laboratory to assess the response of juvenile threadfin and Amyloodinium sp. trophonts to hydrogen peroxide exposure at four dosages: 0, 75, 150, or 300 mg/L for 30 min. In a trial on a commercial farm, a hydrogen peroxide treatment at 75 mg/L for 30 min was applied to juvenile threadfin in a grow-out tank. In both trials, hydrogen peroxide was immediately flushed from the culture system with sea-water after the 30 min exposure period. In the laboratory trial, treatment with 300 mg/L hydrogen peroxide resulted in 100% mortality of the exposed group of fish. However, single treatments with hydrogen peroxide at concentrations of 75 or 150 mg/L eliminated Amyloodinium sp. trophonts without causing loss of fish. In the field trial, a single treatment with 75 mg/L hydrogen peroxide greatly reduced levels of Amyloodinium infestation, and a second treatment 6 d later reduced Amyloodinium trophonts to a nondetectable level. These findings suggest that hydrogen peroxide is a suitable chemical for the treatment of amyloodiniasis of cultured, juvenile Pacific threadfin. [source] Quantitative method for pheromone delivery in studies of sensory adaptation of moth antennaePHYSIOLOGICAL ENTOMOLOGY, Issue 4 2007R. M. TRIMBLE Abstract A pheromone sprayer and an electroantennogram (EAG) are used to study sensory adaptation in the antennae of male obliquebanded leafrollers, Choristoneura rosaceana and oriental fruit moths, Grapholita molesta, to the main pheromone compounds (Z)-11-tetradecen-1-yl acetate (Z11-14:Ac) and (Z)-8-dodecen-1-yl acetate (Z8-12:Ac), respectively. The atomization of 0.125, 0.25, 0.5 or 1 ,L ethanol min,1 into the EAG air delivery tube at an airflow rate of 2 L min,1, with resultant concentrations of 6.25, 12.5, 25 or 50 × 10,5,L ethanol mL air,1, respectively, does not affect the EAG response of C. rosaceana or C. molesta after a 30-min exposure period. The atomization of 0.125 ,L min,1 of a solution of 8 mg Z11-14:Ac mL,1 ethanol into the EAG air delivery tube at an airflow rate of 2 L min,1, with a resultant concentration of 0.5 ng pheromone mL,1 air, reduces the EAG response of C. rosaceana by approximately 70% after a 15-min exposure period. An additional 15 min of exposure to pheromone does not result in increased sensory adaptation. Antennae recover 32% of the lost responsiveness when exposed to pheromone-free air for 15 min. The atomization of 0.125 ,L min,1 of a solution of 8 mg Z8-12:Ac mL,1 ethanol into the EAG air delivery tube at an airflow rate of 2 L min,1, with a resultant concentration of 0.5 ng pheromone mL,1 air, reduces the EAG response of C. molesta antenna by approximately 80% after a 15- or 30-min exposure period. The antennae of this species do not recover responsiveness when exposed to pheromone-free air for 15 min. [source] | ||||||||||