Unimpaired RNA synthesis in neurons and epithelial cells in a freshwater leech exposed to the organophosphate insecticide chlorpyrifos.
Chlorpyrifos (Dursban) is an organophosphate insecticide widely used mainly for control of mosquito larvae. This study used the dominant freshwater leech Nephelopsis obscura as a representative aquatic invertebrate to test toxicity of chlorpyrifos on a nontarget species. RNA synthesis in neurons of the cerebral ganglion, epithelial cells of the intestine, and the tegument of small immature (50-70 mg) and large mature (300-400 mg) N. obscura was examined histochemically with acridine orange fluorochrome after exposure to chlorpyrifos in concentrations of 16, 32, 64, 128, and 144 ppb for as long as 6 weeks. The maximum environmental concentration of this insecticide in lake water, when used properly, is 4.25 ppb. There was no mortality, and no behavioral changes were observed in experimental animals, except for transient curling and cutaneous mucus secretion at the highest concentrations of chlorpyrifos. No pathological changes were observed in the intensity of RNA fluorescence or in the distribution of RNA within the cytoplasm of neurons or epithelial cells in any specimens, unlike N. obscura exposed to anoxia, hyperoxia, or salinity. Chlorpyrifos in the concentrations studied does not appear to adversely affect nucleic acid metabolism in N. obscura.
Singhal
R N
RN
Department of Biological Sciences, University of Calgary, Alta, Canada.
Sarnat
H B
HB
Davies
R W
RW
D000818:Animals; D004390:Chlorpyrifos / Q000494:pharmacology*; D004064:Digestive System / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005724:Ganglia / Q000378:metabolism; D006651:Histocytochemistry; D007865:Leeches; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D012313:RNA / Q000096:biosynthesis*
D012313:RNA; D004390:Chlorpyrifos