PubMed Health⌕ Search

Biomedical subjects

F W Plapp

Publications and source records attributed to F W Plapp.

7 recordsLinked to original sources
PubMed1978

Biochemical genetics of altered acetylcholinesterase resistance to insecticides in the house fly.

Resistance to the organophosphate insecticide tetrachlorvinphos was examined in a house fly (Musca domestica L.) strain with an altered acetylcholinesterase (AChE) of decreased sensitivity to inhibition by the insecticide. Genetic tests showed that both resistance and the altered AChE were controlled by semi-dominant gene(s) on chromosome II. The gene for resistance was five crossover units from the mutant marker stubby wing (stw). A house fly strain was prepared in which resistance was introduced in to a susceptible stw strain by recombination. Biochemical assays revealed that the altered AChE was introduced along with resistance. Assays of the AChE of resistant and susceptible stw strains by two independent methods showed that the enzyme from resistant flies was 30 times more slowly inhibited by tetrachlorvinphos than the enzyme from susceptible flies.

Acetylcholinesterase↗
PubMed1978

Induction of multiple cytochrome P-450 species in housefly microsomes--SDS-gel electrophoresis studies.

1. Microsomal fractions isolated from various housefly strains have been characterized with respect to multiple forms of cytochrome P-450 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 2. Susceptible NAIDM houseflies were pretreated with known inducers of cytochrome P-450, and their microsomal electrophoretic profiles were compared to control NAIDM microsomes, using as standards partially purified cytochrome P-450s from noninduced NAIDM houseflies. 3. Tentatively, at least five different species of cytochrome P-450 may exist in the NAIDM housefly strain. 4. A comparison of the microsomal electrophoretic profile of different housefly strains also indicates the presence of at least two additional cytochrome P-450 species. 5. Induction with alpha-pinene and phenobarbital was expressed by a shift of the maximum absorbance at 452 nm in the CO-difference spectrum to lower wavelengths in the NAIDM strain; whereas, beta-naphthoflavone, although increasing the amount of cytochrome P-450, did not change the wavelength of maximum absorbance. 6. Cytochromes of the P-452 type appear to predominate in the susceptible NAIDM strain, while cytochromes of the P-450 and P-448 types predominate in resistant strains.

Animals↗
PubMed1976

Snakes as indicators of environmental contamination: relation of detoxifying enzymes and pesticide residues to species occurrence in three aquatic ecosystems.

Pesticide detoxifying enzymes and residues of p,p'-DDE and PCB were measured in snakes of two genera collected in three aquatic ecosystems in central Texas. Snake genera were Agkistrodon (water moccasins and copperheads) and Natrix (water snakes). One collecting site had heavy exposure to insecticides, one to PCBs and one to neither. Objectives were to correlate pesticide residues and detoxifying enzymes with species occurrence in different ecosystems, to evaluate the usefulness of snakes as indicators of environmental contamination, and to establish a biochemical basis for the differential distribution of snakes between ecosystems. Agkistrodon spp. had several times the NADPH-dependent oxidative detoxifying activity of Natrix spp. Within Natrix, oxidase activity was significantly higher in erythrogaster and fasciata than in rhombifera. Alkyltransferase activity was higher in A. piscivorus (water moccasins) than in any other species. There were no consistent differences between sexes in levels of detoxifying enzymes and enzyme activity was similar in snakes of each species from all collecting sites, indicating no induction had occurred as a result of heavy exposure to insecticides or PCBs. DDE residues were highest in snakes collected adjacent to a cotton agro-ecosystem. PCB residues occurred only in snakes collected near a heavily-traveled highway. Residues in A. piscivorus were only half those in Natrix spp. from the same site, indicating the former is more efficient as disposing of residues. The data indicate that snakes with high levels of detoxifying enzymes, particularly microsomal oxidases, are more likely to occur in a contaminated ecosystem than snakes with less active detoxifying enzymes and that residues are lower in the better detoxifiers. Snakes are apparently excellent indicators of environmental contaminated by insecticides and other persistent chemicals.

Adipose Tissue↗