Isoform-specific expression of the neuropeptide orcokinin in Drosophila melanogaster

Peptides. 2015 Jun:68:50-7. doi: 10.1016/j.peptides.2015.01.002. Epub 2015 Jan 16.


Orcokinins are neuropeptides that have been identified in diverse arthropods. In some species, an orcokinin gene encodes two isoforms of mature orcokinin peptide through alternative mRNA splicing. The existence of two orcokinin isoforms was predicted in Drosophila melanogaster as well, but the expression pattern of both isoforms has not been characterized. Here, we use in situ hybridization, antibody staining, and enhancer fusion GAL4 transgenic flies to examine the expression patterns of the A and B forms of orcokinin, and provide evidence that they are expressed differentially in the central nervous system (CNS) and the intestinal enteroendocrine system. The orcokinin A isoform is mainly expressed in the CNS of both larvae and adults. The A form is expressed in 5 pairs of neurons in abdominal neuromeres 1-5 of the larval CNS. In the adult brain, the A form is expressed in one pair of neurons in the posteriorlateral protocerebrum, and an additional four pairs of neurons located near the basement of the accessory medulla. Orcokinin A expression is also observed in two pairs of neurons in the ventral nerve cord (VNC). The orcokinin B form is mainly expressed in intestinal enteroendocrine cells in the larva and adult, with additional expression in one unpaired neuron in the adult abdominal ganglion. Together, our results provide elucidation of the existence and differential expression of the two orcokinin isoforms in the Drosophila brain and gut, setting the stage for future functional studies of orcokinins utilizing the genetically amenable fly model.

Keywords: Drosophila melanogaster; Neuropeptide; Orcokinin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Central Nervous System / cytology
  • Central Nervous System / metabolism
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / metabolism*
  • Enteroendocrine Cells / metabolism
  • Gene Expression
  • Intestinal Mucosa / metabolism
  • Intestines / cytology
  • Male
  • Molecular Sequence Data
  • Neuropeptides / genetics
  • Neuropeptides / metabolism*
  • Organ Specificity
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism


  • Drosophila Proteins
  • Neuropeptides
  • Protein Isoforms
  • orcokinin