Rnb^f04616/+, Rnb^f04616/Rnb^f04616, Rnb^f04616/Rnb^f05400 and Rnb^f04616/Df(3R)BSC547 adults previously entrained under 12h:12h light:dark cycles exhibit a significant decrease in the proportion of circadian rhythmic individuals upon shift to constant darkness conditions, despite exhibiting an apparently normal circadian period, as compared to controls; this decrease is mild in the heterozygotes and more severe in the homozygotes and transheterozygotes.

In Rnb^f04616 homozygous adults kept under 12h:12h light:dark cycle conditions, the dendritic tree of s-LNv neurons fail to exhibit rhythmic increases in area, as compared to controls.