Dept. of Life Sciences, Osaka Prefecture Univ., 1-1 Gakuen-cho, Sakai, Osaka 593, Japan,
The para locus of Drosophila melanogaster encodes an alpha subunit of the
voltage-sensitive sodium channel (Loughney et al., 1989). para is
ubiquitously transcribed throughout the CNS and PNS at all developmental
stages (Hong and Ganetzky, 1994).
For the analysis of the functions of the para gene in the nervous
systems of living organisms, we investigated the several aspects of the
para mutants related to behaviors, utilizing the following three para
alleles. para[hd838] has an internally deleted P-element in the second
intron, 279-bp upstream from the third exon (Tanaka et al., 1993).
para[ts1] is supposed to have insertion and/or deletion in the third intron
(Loughney et al., 1989). para[sbl1] is supposed to have the mutation close
to the 3' terminal (Lilly et al., 1994).
para[hd838] underwent paralysis at 37°C(B as well as many mutations at t
he para locus, while para[sbl1] did not. Both para[hd838] and para[ts1]
showed higher sensitivities to diethylether anesthesia than the wild type,
the 50% effective doses (ED50s) for the females of the para[hd838],
para[ts1] and Canton-S were 1.33%atm., 1.67%atm. and 1.99%atm,
respectively. These results indicate that the sodium channel(s) encoded by
the para locus play important roles both in the neuronal cells involved in
the heat-induced paralysis and those involved in the diethylether
anesthesia, but we don't know that the heat and diethyether have the same
target sites of the sodium channel molecules.
We are analyzing the sensitivity to diethylether anesthesia of the
para[sbl1], to investigate whether diethylether act on the restricted site
of the sodium channel molecules. In addition, we are analyzing the
knock-down (dyskinesia) effects of ionizing radiation on the three alleles
which was found to be antagonized by diethylether (Gamo et al., 1985), to
see how the para gene is involved in the knock-down response.
These studies would give the bases to reveal the functions of the huge
sodium channel molecules in the living organisms.