Flies homozygous for e(sei)1 by itself, when their container is tapped lightly, become hyperactive and unable to crawl up the sides of the container to the top. e(sei)1 flies exhibit spontaneous neuronally stimulated firing of the dorsal longitudinal muscle and greatly enhances such firing of sei2. Also e(sei)1 does not affect saxitoxin binding by membrane extracts as do sei mutations.
In the homozygous condition e(sei)1 lowers the temperature threshold of two temperature-sensitive alleles of sei. sei2, which is a dominant paralytic at 40oC, a recessive paralytic at 38oC and nonparalytic at 35oC, becomes a dominant paralytic at 38oC and displays a recessive hyperactive uncoordinated phenotype at 35oC in the presence of homozygous, but not heterozygous e(sei)1. Homozygous sei1 which is normal at 35oC becomes paralyzed at that temperature in the presence of homozygous e(sei)1.
