Fig. 6. Distribution of heart period and intervals is altered when mlp84B is absent or down-regulated in the heart. The frequency of heart period (HP), diastolic interval (DI) and systolic interval (SI) durations is represented for all heartbeats from all analyzed recordings. (A) One week old mlp84B^–/– flies display globally longer and more irregular heart period and diastolic interval than wild-type or mlp84B^–/– rescue flies. The dashed vertical lines indicate the most frequent duration for each interval in wild-type and mlp84B^–/– rescue flies. Systolic interval appears to be unaffected. (B) Cardiac mlp84B mRNA knockdown results in overall longer and highly irregular heart period and diastolic interval in 5 week old flies. Systolic interval is moderately prolonged relative to 1 week old wild-type in A. The heart period and diastolic/systolic interval distributions were not obviously affected in 1 week old mlp84B RNAi-expressing hearts compared with corresponding controls (not shown).