Charles O. Knowles

Effects of fenvalerate on biochemical parameters, survival, and reproduction of Daphnia magna

Daphnia magna were exposed to fenvalerate at nominal concentrations of 0.5, 0.25, 0.13, 0.06, and 0.03 micrograms/liter for 21 days. On Days 7 and 21 of exposure, levels of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), adenosine diphosphate (ADP), adenosine triphosphate (ATP), glycogen, and lipid were measured, and the results were related to survival and reproduction during the 21-day test period. Survival was not significantly (alpha = 0.05) affected by the 21-day exposure; however, reproduction was reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. On Day 7, protein, RNA, ADP, caloric equivalents, and glycogen were also significantly reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. Thus, these biochemical parameters identified the same no observable effect concentration (NOEC) as did reproduction. Variables derived from biochemical parameters were related to reduced protein growth and reproduction. Decreases in protein/RNA and glycogen/lipid ratios and increases in ADP/DNA, ADP/ATP, protein/RNA/DNA, and lipid/DNA ratios were observed at Day 7 for those daphnia exposed to 0.5 micrograms/liter of fenvalerate. The only derived variable that reflected the reduced protein growth at Day 7 in daphnia exposed to 0.25 micrograms/liter of fenvalerate was the glycogen/lipid ratio. Biochemical determinations at Day 21 indicated that the organisms exposed to 0.25 micrograms/liter of fenvalerate were not different from controls, whereas those exposed to 0.5 micrograms/liter were still affected.

Toxicity of pyrethroids and effect of synergists to larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae).

Abstract Based on 48 h LD50 estimates from topical bioassays, cypermethrin was more toxic than permethrin to Helicoverpa zea (Boddie) larvae and adults; however, the two pyrethroids did not differ significantly in their relative toxicities to Spodoptera frugiperda (J. E. Smith) and Agrotis ipsilon (Hufnagle). Larvae of each species generally were more susceptible to cypermethrin and permethrin than respective adults. The only exception to this generalization occurred with H. zea where slight overlap of the 95% confidence intervals with larvae and adult males was observed with cypermethrin. Respective males and females of the three species usually did not differ significantly in their susceptibility to either cypermethrin or to permethrin; however, with A. ipsilon, females were more susceptible to permethrin than to cypermethrin. Several instances of greater than additive toxicity were noted when insects were treated with piperonyl butoxide, S,S,S-tri-n-butyl phosphorotrithioate (DEF), or amitraz 30 min before cypermethrin. DEF exhibited the broadest spectrum of synergistic activity.

Formamidine Pesticides — Metabolic Aspects of Neurotoxicity

Formamidines are a relatively new class of agricultural chemicals, and within this group there exist diverse types of pesticidal activity. For example, compounds active as herbicides, fungicides, nematocides, bactericides, insecticides, and acaricides have been discovered. The insecticide and acaricide N′-(4-chloro-o-tolyl)-N,N-dimethylformamidine or chlordimeform has received the most attention from a toxicological standpoint since it has been used extensively for insect and acarine control (Knowles, 1976).

Protein and nucleic acid content in Daphnia magna during chronic exposure to cadmium

Daphnia magna Straus were exposed to cadmium concentrations of 0, 0.4, 0.8, 2.1, 4.3, and 7.2 micrograms/liter for 21 days. Protein, RNA, DNA, glycogen and lipid content were measured after 4, 7, and 21 days of exposure, and the results were related to survival and reproduction. The no observed effect concentration (NOEC) for survival, protein growth, and reproduction at Day 21 was 2.1, 0.8, and 0.8 microgram/liter cadmium, respectively. Protein growth was most sensitive to cadmium exposure following the rapid growth phase which occurred between Days 4 and 6 of growth and development. All concentrations of cadmium produced significant reductions in protein growth at Day 7 indicating that the NOEC was less than 0.4 micrograms/liter. RNA:protein and protein:RNA:DNA ratios, which are related to the growth rate of daphnids, were most appropriately monitored at Day 4 which was prior to the rapid growth phase. Protein:RNA:DNA ratio at Day 4 identified the same NOEC as identified by protein growth and reproduction after 21 days of exposure.

Protein, nucleic acid and adenylate levels in Daphnia magna during chronic exposure to chlordecone

Abstract The relationships between levels of several biomolecules and survival and reproduction were investigated in Daphnia magna exposed for 21 days to chlordecone concentrations ranging from zero to 60 μg litre −1 . Biomolecules, which included total protein, ribonucleic acid, deoxyribonucleic acid, adenosine diphosphate and adenosine triphosphate, were monitored on days 7 and 21. The highest no observable effect concentration (NOEC) based on survival and reproduction was 11·2 μg litre −1 chlordecone. Although the level of each biomolecule per individual daphnid was decreased in a concentration-dependent manner by exposure to chlordecone, protein was most sensitive and had the same NOEC as survival and reproduction. The relative sensitivity of these three parameters when expressed as percent of control was survival > reproduction > protein. RNA/DNA and ADP/ATP ratios were not significantly affected by chlordecone exposure; however, ratios of protein/RNA/DNA and ATP/DNA were significantly increased in daphnia exposed to 48·4 μg litre −1 chlordecone.

Metabolism of diazinon by fish liver microsomes

ConclusionsThe results of these experiments indicate that thein vitro metabolism of diazinon is accomplished by enzyme preparations from fish liver homogenates, with the microsomal fraction being most active. The enzyme system responsible for diazinon metabolism in channel catfish liver microsomes required NADPH and oxygen for the oxidative desulfuration of diazinon to diazoxon, and probably for cleavage of diazinon and diazoxon to diethyl phosphorothioic acid and diethyl phosphoric acid, respectively. Thus, these reactions are presumed to be catalyzed by the NADPH-cytochrome P450 mixed function oxidase system. The only slight increase in diazinon metabolism by channel catfish hepatic microsomal or soluble enzymes with exogenous GSH suggests that GSH-dependent enzymes were not very active.

Nicotinic and muscarinic cholinergic receptors in honey bee (Apis mellifera) brain.

Abstract 1. Honey bee head homogenates contained particulate components capable of binding the nicotinic receptor antagonist α-bungarotoxin (BGT) and the muscarinic receptor antagonist quinuclidinyl benzilate (QNB). Specific binding of [125I]BGT (denned by nicotine) and [3H]QNB (defined by atropine) was heat sensitive, linear with tissue concentration, and saturable. Bmax values were 204 fmol mg protein−1 for [125I]BGT and 57 fmol mg protein−1 for [3H]QNB yielding a binding site ratio of 3.6:1. Hill coefficients were 1.0 for each radioligand. 2. Binding by both radioligands was rapid and reversible. Association (k+1) and dissociation (k−1) rates were 1.38 × 106 s−1 M−1 and 6.2 × 10−4 s−1 for [125I]BGT and 3.27 × 106 s−1 M−1 and 9.4 × 10−5 s−1 for [3H]QNB. The dissociation rate constants (KD) were 450 pM ( k −1 k +1 ) and 743 pM (saturation) for [125I]BGT and 30pM ( k −1 k +1 ) and 96 pM (saturation) for [3H]QNB. 3. Pharmacological profiles were nicotinic for [125I]BGT with nicotine (Ki 2.6 × 10−7 M), d -tubocurarine (Ki 1.0 × 10−6 M), and ACh + dichlorvos (Ki 4.5 × 10−6 M) being the most potent inhibitors and muscarinic for [3H]QNB with (±)-QNB (Ki 2.2 × 10−12M), S( + )-dexetimide (Ki 2.9 × 10−11 M), atropine (Ki 6.9 × 10−10M), and scopolamine (Ki 4.1 × 10−10M) being most potent. 4. It appeared that [125I]BGT and [3H]QNB were binding with high affinity to honey bee brain populations of nicotinic and muscarinic cholinergic receptors, respectively.

Effects of aluminum on the biochemical composition of Atlantic Salmon

Biomolecule content, dry weight, and wet weight of Atlantic salmon,Salmo salar L., were monitored during 60-day exposure to aluminum, which began before hatch and extended to about the end of the alevin stage. The Atlantic salmon exposed to aluminum concentrations of 0, 33, 71, 124, or 264 μg/L at pH 5.5 for 60 days were evaluated for growth, survival, and biochemical effects on days 15, 30, and 60. Growth and survival were significantly reduced at the two highest aluminum concentrations by day 60. RNA and DNA were the most sensitive biomolecules monitored and were significantly reduced at the three highest aluminum concentrations by day 60. RNA∶protein and RNA∶DNA ratios were no more responsive than growth and survival. The lipid content of salmon was not significantly affected by exposure to aluminum. It was concluded that biomolecule content or ratios were not particularly sensitive indicators of growth effects in Atlantic salmon exposed to aluminum.

Effects of organotins on rat platelets

Incubation of rat platelets with organotins inhibited their capacity to take up 5-hydroxytryptamine-14C (5-HT-14C) and stimulated the release of preloaded 5-HT-14C as well as endogenous 5-HT. Similar but less pronounced effects also were observed when platelets from rats treated intraperitoneally with organotins were examined. The relationships of organotin structure to 5-HT uptake inhibition and 5-HT release were similar, with the most active compounds being the trisubstituted derivatives bis(tri-n-butyltin) oxide, tri-n-butyltin chloride, tricyclohexyltin hydroxide, tri-n-propyltin chloride, and triphenyltin hydroxide. Scanning electron micrographs revealed increased platelet aggregation and shape change in organotin treated samples as compared to vehicle treated controls. It was suggested that the action of organotins on rat platelets was due, at least in part, to their known ability to interfere with ATPase mediated systems.

Biogenic amine uptake by nerve cords from the American cockroach and the influence of amidines on amine uptake and release

Uptake of 5-hydroxytryptamine (5-HT) by isolated whole nerve cords of the American cockroach, Periplaneta americana (L.), involved a dual component system, with one component consisting of rapid active uptake and the other of passive diffusion. Using high performance liquid chromatography with electrochemical detection, it was shown that nerve cords contained 5-HT levels of about 350 ng/g and an equivalent amount of 5-hydroxyindoleacetic acid (5-HIAA), a 5-HT metabolite not previously reported in cockroach nerve cords. Amidines had no discernable effect on uptake of 5-HT or octopamine by nerve cords or on endogenous levels of 5-HT and 5-HIAA in cords.