SummaryThe 2-stage determination is based on changes in blood coagulation activity brought about both by the administration of warfarin in conjunction with vitamin KJ epoxide and by feeding a vitamin K-free diet for 4 days. When it was applied to laboratory-bred rats of known warfarin-resistance genotype, 35/35 homozygous susceptible, 44/44 homozygous resistant and 131/133 heterozygous rats were correctly classified. This method was equally effective in identifying the genotype of wild rats carrying the warfarin-resistance gene, Rw 2 • The procedure is rapid and accurate.

Lethal and sublethal doses (0.33 or 0.5 X LD^, LD^, and 2 or 3 X LD^) of five commonly used carbamate pesticides (aldicarb, methiocarb, oxamyl, pirimicarb, and thiofanox) were administered to Japanese quail.Acetyl cholinesterase (AChE), cholinesterase (ChE), and -naphthyl acetate esterase activities were measured in plasma at 2 and 24 h or at death. Brain AChE activities were measured in fresh tissue extracts and after 7 days post-mortem. Tissue-specific enzymes glutamate dehydrogenase (GDH), glutamate oxaloacetate transaminase (GOT), and sorbitol dehydrogenase were also measured in the plasma at 2 and 24 h or at death. Lethal doses of carbamates gave >64% inhibition of plasma AChE and >75% inhibition of plasma ChE. Plasma esterase activities at 24 h after dosing generally returned to control levels or above. Lethal doses of carbamates produced ~40-60% inhibition of brain AChE although the maximal inhibition for pirimicarb treatment was 97%. A dose-response relationship for brain AChE was only found in lethally dosed quail given oxamyl and pirimicarb. No birds surviving the carbamate treatments at 24 h showed significant inhibition of brain AChE, and birds surviving doses of aldicarb, methiocarb, and pirimicarb showed elevated esterase levels. After 24 h, increases in plasma GOT levels were observed in survivors from all the carbamate treatments. Elevation in plasma GDH levels were observed only in survivors from the aldicarb treatments. The changes resulting from sublethal carbamate