We performed EMS mutagenesis on npr-1(ky13) animals, and subjected their F2 progeny to a behavioral screen. We treated the animals with ethanol, allowed them time to develop AFT, and then identified animals that had not developed tolerance using a locomotion assay in which animals that could not develop tolerance would be too impaired by ethanol to crawl to an attractive odorant. We isolated animals that had not developed tolerance, allowed them to produce self-progeny, and retested their progeny in a quantitative assay of basal activity and ethanol responses that measured both initial sensitivity and the development of AFT. In this secondary assay, we placed worms on plates that were contained 0 mM or 400 mM of ethanol. Movies were recorded of locomotion at 10 and 30 minutes of treatment, and speed was determined by computer analysis of the movies. We define the decrease in speed at 10 minutes of treatment, relative to untreated animals of the same genotype, as the initial sensitivity of animals to ethanol. We have previously shown that wild-type worms move faster at 30 minutes relative to
