Search for candidate gonadotropins in extracts of the corpus cardiacum of the fleshfly, **Neobellieria bullata**
Faculty of Sciences. Biology
Invertebrate reproduction and development. - Rehovot
, p. 119-125
No single fly gonadotropin has as yet been identified with certainty. Dababase analysis fails to yield positive results when the genomic database of Drosophila is scanned for the presence of family members of gonadotropins that have already been identified in other insects. However, a candidate gonadotropic peptide (cAMP generating peptide, Neb-cGP) was purified some time ago from the fleshfly Neobellieria bullata. A short form of this peptide was found to stimulate cAMP production in the ovaries of the fleshfly. In the present study, we gathered additional arguments that suggest a role for Neb-cGP as a gonadotropic hormone. Brains of male and female adult Neobellieria bullata were stained with antiserum directed to the cAMP generating peptide. In both sexes four lateral neurosecretory cells in the dorsal part of each pars lateralis were stained. In addition, mass spectrometric read-outs of extracts of fleshfly corpora cardiaca displayed the full length form (48 amino acid residues) of the cAMP-generating peptide. These findings suggest that Neb-cGP is synthesised in the brain and stored in and released from the corpora cardiaca as a neurohormone. The -terminal 15-mer isoform. of the cAMP generating peptide could not be identified. Injection experiments in the fleshfly with this 15-mer peptide, that were set up to examine the in vivo effect, suggest a putative stimulatory effect on oocyte development. Attempts to identify a fly neuroparsin-like peptide through mass spectrometry, purification and microsequencing by Edman degradation or advanced Blast searches in the Drosophila genome all failed.