ETHANOL-INDUCED ANESTHESIA IN INBRED STRAINS OF LONG-SLEEP AND SHORT-SLEEP MICE - A GENETIC-ANALYSIS OF REPEATED-MEASURES USING CENSORED-DATA

We present a repeated-measures, genetic analysis of ethanol-induced an esthesia (sleep time) in mice from the inbred long-sleep (ILS) and sho rt-sleep (ISS) strains of mice and their derived F-1 and F-2 generatio ns. Mice (total N > 1300) were administered a 4.1 g/kg intraperitoneal dose of ethanol at two times, 7 to 10 days apart. A method suggested by Cohen was used to analyze the resulting data, which contained a kno wn number of unmeasured observations. A genetic model that included bo th additive and epistatic parameters fitted the adjusted data well. A novel procedure for estimating heritability, based on a comparison of repeatability coefficients from the isogenic and genetically segregati ng populations, was also employed. Results of this analysis suggested that the heritability for individual measurements of sleep time is abo ut .30, whereas the heritability of average scores is about .40. Resul ts of this analysis also confirm that the ILS and ISS strains differ f or genes at seven or more loci that influence sleep time. Since the IL S and ISS were derived by inbreeding the LS and SS lines, these result s further suggest that almost all of the genetic variation present in the selected lines have been maintained in the ILS and ISS strains.