Depts of ~Biological Chemistry, and § Biology, University of Michigan, Ann Arbor, Michigan, USA 48109-1048,
Although Drosophila has served as a versatile experimental
organism for developmental neurobiology little is known about the
action of neuropeptides due to the lack of structure data,
antisera specific to individual neuropeptides, and bioassays.
We have isolated TDVDHVFLRFamide, Drosophila myosuppressin or
dromyosuppressin (DMS), generated sequence-specific antisera to
DMS, and established in vivo and in vitro assays to study the
cardioinhibitory action of DMS.
Myosuppressin peptides, isolated from several organisms,
have a high degree of structure identity. Only the N-terminal
amino acid residue differs between EDVDHVFLRFamide or leuco-
myosuppressin, LMS, isolated from cockroach and PDVDHVFLRFamide
or SchistoFLRFamide, isolated from locust.
Antisera raised to TDVDHV were used to determine the
expression pattern of DMS at all stages of development. DMS
immunoreactive material is present in neural and gastrointestinal
tissue. Immunoreactive projections from neurons in the superior
protocerebrum impinge on the anterior of the dorsal vessel.
We have determined that serotonin increases Drosophila heart
rate. A mixture of serotonin and DMS has an additive effect
suggesting that the two substances act through different
mechanisms. The action of DMS is suppressed in potassium channels
mutants and in the presence of potassium channel blockers,
supporting the conclusion that the regulation of heart rate
involves potassium channels. Supported by NSF and AHA/MI.