Search PubMed⌕ Search

Biomedical subjects

E E Little

Publications and source records attributed to E E Little.

9 recordsLinked to original sources
PubMed2001

Cholinergic and behavioral neurotoxicity of carbaryl and cadmium to larval rainbow trout (Oncorhynchus mykiss).

Pesticides and heavy metals are common environmental contaminants that can cause neurotoxicity to aquatic organisms, impairing reproduction and survival. Neurotoxic effects of cadmium and carbaryl exposures were estimated in larval rainbow trout (RBT; Oncorhynchus mykiss) using changes in physiological endpoints and correlations with behavioral responses. Following exposures, RBT were videotaped to assess swimming speed. Brain tissue was used to measure cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number, and MChR affinity. ChE activity decreased with increasing concentrations of carbaryl but not of cadmium. MChR were not affected by exposure to either carbaryl or cadmium. Swimming speed correlated with ChE activity in carbaryl-exposed RBT, but no correlation occurred in cadmium-exposed fish. Thus, carbaryl exposure resulted in neurotoxicity reflected by changes in physiological and behavioral parameters measured, while cadmium exposure did not. Correlations between behavior and physiology provide a useful assessment of neurotoxicity.

Animals↗
PubMed2001

Behavioral dysfunctions correlate to altered physiology in rainbow trout (Oncorynchus mykiss) exposed to cholinesterase-inhibiting chemicals.

We selected four metrics of swimming behavior (distance swam, speed, rate of turning, and tortuosity of path) and the commonly used biochemical marker, brain cholinesterase (ChE) activity, to assess (1) the sensitivity and reliability of behavior as a potential biomarker in monitoring work, (2) the potential for these endpoints to be used in automated monitoring, and (3) the linkage between behavior and its underlying biochemistry. Malathion-exposed fish exhibited large decreases in distance and speed and swam in a more linear path than control fish after 24 h exposure. By 96 h exposure, fish still swam slower and traveled less distance; fish fully recovered after 48 h in clean water. Diazinon-exposed fish exhibited decreases in distance, speed, and turning rate compared to controls. After 48 h recovery in clean water, fish exposed to diazinon had not recovered to control levels. The behavioral responses provided measures of neurotoxicity that were easily quantifiable by automated means, implying that the inclusion of behavior in monitoring programs can be successful. Furthermore, correlations between behavior and biochemical endpoints, such as ChE inhibition, suggest that this approach can provide a meaningful link between biochemistry and behavior and can provide useful information on toxicant impacts.

Animals↗
PubMed1992

Aquatic hazard assessment of the organophosphate insecticide fonofos.

This study determined the acute and chronic toxicity of the organophosphate insecticide fonofos to standard freshwater aquatic organisms under laboratory conditions. Fonofos was acutely toxic to bluegill (Lepomis macrochirus), Daphnia (D. magna), and midge (Chironomous riparius) at 5.3, 2.7, and 39 micrograms/L, respectively. Three fonofos formulations (technical, 94.8% A.I.; 20G, field granular 20% A.I.; and 4E, field liquid 4#/gal A.I.) exhibited similar acute toxicities to bluegill. Exposure to fonofos delayed reproduction and decreased the intrinsic rate of increase of Daphnia during 21-d chronic exposure at the lowest tested concentration (0.08 micrograms/L). The no observable effect concentration (NOEC) for Daphnia survival was 0.42 micrograms/L; 0% survival occurred at the lowest observable effect concentration (LOEC) of 1.45 micrograms/L. The NOEC for midge emergence was 3.42 micrograms/L; only 34% emergence occurred at the LOEC of 8.24 micrograms/L. Chronic 30-d exposure of juvenile bluegills decreased growth and survival at 5.65 micrograms/L (LOEC), but no effects occurred at 2.33 micrograms/L (NOEC). The relative hazard of fonofos to aquatic life is similar to other carbamate and organophosphate corn insecticides.

Animals↗
PubMedDate not supplied

Behavioral indicators of sublethal toxicity in rainbow trout.

Four measures of behavior--spontaneous swimming activity, swimming capacity, feeding behavior, and vulnerability to predation--were assessed as indicators of sublethal toxicity in rainbow trout (Oncorhynchus mykiss) in 96-hr exposures to sublethal concentrations of six agricultural chemicals: carbaryl, chlordane, dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-DMA), tributyl phosphorotrithioate (DEF), methyl parathion, and pentachlorophenol. After exposures, behavioral changes consistently demonstrated sublethal toxicity, but effects on specific behaviors varied with contaminants and their concentrations were altered by the water quality criterion concentration for chlordane (2 micrograms/L), and at a concentration of DEF (5 micrograms/L) that had previously been shown to inhibit growth and survival after a 90-day exposure. Feeding behavior was inhibited most by exposure to DEF, 2,4-DMA, and methyl parathion. Vulnerability to predation was heightened most by exposure to carbaryl and pentachlorophenol. Although all chemicals inhibited spontaneous swimming activity, only carbaryl, DEF, and 2,4-DMA influenced swimming capacity.

Animals↗