Molecular cloning of [Thr⁴, His⁷]-corazonin (Apime-corazonin) and its distribution in the central nervous system of the honey bee Apis mellifera (Hymenoptera: Apidae)

Abstract

Corazonin (Crz) is a neuropeptide with a conserved structure and distribution pattern in the central nervous system (CNS) of many insects. We cloned the Crz gene from brains of the honey bee workers (Apis mellifera L., Apime). The ApimeCrz cDNA comprises 502 base pairs and encodes a new form of corazonin displaying Thr⁴ substitution of [His⁷]-corazonin. In workers of A. mellifera, corazonin immunoreactivity was found in a group of four to five lateral neurosecretory cells (LNSC) in each hemisphere of the protocerebrum and in lateral paired neurons segmentally distributed in the ventral ganglia. However, the ApimeCrz mRNA was transcribed only in the LNSC. The Crz LNSC projected into the ipsilateral corpus cardiacum. The pattern of distribution of corazonin immunoreactive material in the CNS suggests that Apime-corazonin plays roles as a neurohormone as well as a neurotransmitter or neuromodulator. The effects of this neuropeptide on the induction of dark color in albino nymphs of Locusta migratoria and spinning rate in spinning larvae of Bombyx mori were assayed. The results indicate that Apime-corazonin shows biological activities comparable to those for [Arg⁷]- and [His⁷]-corazonins.