title: Myoinhibitory peptide (MIP) immunoreactivity in the visual system of the blowfly Calliphora vomitoria in relation to putative clock neurons and serotonergic neurons.
abstract: A few types of peptidergic clock neurons have been identified in the fruitfly Drosophila, whereas in blowflies, only pigment-dispersing factor (PDF)-immunoreactive lateral ventral clock neurons (LN(v)s) have been described. In blowflies, but not Drosophila, a subset of these PDF-expressing neurons supplies axon branches to a region outside the synaptic layer of the lamina, the most peripheral optic lobe neuropil. In Drosophila, similar lamina processes are instead supplied by non-clock neurons (LMIo) that express myoinhibitory peptide (MIP). We have investigated the distribution of MIP-immunoreactive neurons in the visual system of the blowfly Calliphora vomitoria and found neurons resembling the three LMIos, but without processes to the lamina. In Calliphora, PDF-immunoreactive processes of LN(v)s in the lamina closely impinge on branching serotonin-immunoreactive axon terminations in the same region. We have also identified, in the blowfly, two types of putative clock neurons that label with an antiserum to ion-transport peptide (ITP). The presence of serotonin-immunoreactive neurons supplying processes to the lamina seems to be a conserved feature in dipteran flies. The morphology of the two types of ITP-immunoreactive clock neurons might also be conserved. However, peptidergic neurons with branches converging on the serotonin-immunoreactive neurons in the lamina are of different morphological types and express PDF in blowflies and MIP in Drosophila. The central circuitry of these PDF- and MIP-expressing neurons probably differs; consequently, whether their convergence on serotonergic neurons subserves similar functions in the two species is unclear.
authors.affiliation: Department of Zoology, Stockholm University, Stockholm, Sweden.
authors.forename: Agata
authors.initials: A
authors.lastname: Kolodziejczyk
authors.forename: Dick R
authors.initials: DR
authors.lastname: Nässel
mesh_terms: D000818:Animals; D001683:Biological Clocks; D004175:Diptera / Q000166:cytology / Q000378:metabolism*; D005260:Female; D008297:Male; D008954:Models, Biological; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D014795:Visual Pathways / Q000166:cytology / Q000378:metabolism*
chemical_list: D010455:Peptides; D012701:Serotonin; C027714:melanophore-dispersing hormone