Genetic variation affecting heart rate in Drosophila melanogaster

Heart rate in pre-pupae of Drosophila melanogaster is shown to vary over a wide range from 2.5 to 3.7 beats per second. Quantitative genetic analysis of a sample of 11 highly inbred lines indicates that approaching one-quarte r of the total variance in natural populations can be attributed to genetic differences between flies. A hypomorphic allele of the potassium channel g ene ether-a-gogo, which is homologous to a human long-QT syndrome susceptib ility gene (HERG), has a heart rate at the low end of the wild-type range, but this effect can be suppressed in certain wild-type genetic backgrounds. This study provides a baseline for investigation of pharmacological and ot her physiological influences on heart rate in the model organism, and impli es that quantitative genetic dissection will provide insight into the molec ular basis for variation in normal and arrhythmic heart function.