Untitled

Abstract

A salivary gland salivation stimulating peptide was identified from the salivary glands of the migratory locust by its ability to stimulate cAMP production in the same tissue. The gene coding for this peptide has recently been shown to code for a precursor consisting of a signal peptide, several copies of the peptide separated by Lys-Arg doublets and a few other peptides. These data are consistent with it being a neuropeptide. However, antiserum raised to this peptide labels the acini of the salivary glands while RT-PCR only gives positive results in the salivary gland, but not in any ganglion of the central nervous system. Thus, this peptide is not a neuropeptide as previously assumed. A salivary gland salivation stimulating peptide was identified from the salivary glands of the migratory locust by its ability to stimulate cAMP production in the same tissue. The gene coding for this peptide has recently been shown to code for a precursor consisting of a signal peptide, several copies of the peptide separated by Lys-Arg doublets and a few other peptides. These data are consistent with it being a neuropeptide. However, antiserum raised to this peptide labels the acini of the salivary glands while RT-PCR only gives positive results in the salivary gland, but not in any ganglion of the central nervous system. Thus, this peptide is not a neuropeptide as previously assumed. , 2015 ; van Hiel et al., 30 2010). Inhibition or at least disruption of feeding by insects would be very attractive as it would 31 presumably avoid or diminish economic damage, or in the case of disease vectors, might reduce 32 transmission of infectious agents. As production of saliva is usually a first and necessary step in 33 feeding the regulation of salivation by neuropeptides is particularly interesting. PeerJ Preprints 34A pentadecapeptide was isolated from the salivary glands of the migratory locust by its 35 ability to stimulate the production of cAMP in the same glands at concentration of 10 -6 M 36 (Veelaert et al., 1995). As it also stimulates salivation (Veelaert et al., 1995), its characteristics 37 suggests it to be neuropeptide that likely acts as a neurotransmitter rather than a hormone. If it 38 were a hormone, one would expect it to stimulate the production of cAMP and salivation in the 39 nanomolar , rather than in the micromolar range and it would be expected in a neurhemal organ, 40 rather than in the salivary gland itself (Veelaert et al., 1995). Unlike most insect neuropeptides 41 orthologs of this peptide have not been identified from any other arthropod, suggesting that it 42 may not be universally present in insects. This might be advantageous as any pesticide based on 43 it could be relatively selective. The genome sequence of the migratory locust (Wang et al., 2014) 44 showed that the predicted precursor encoding this peptide has all the hallmarks of a classical 45 neuropeptide precursor: a signal peptide and a propeptide encoding multiple copies of the 46 peptide separated by Lys-Arg convertase cleavage sites (...