The contribution of the genomes of a termite and a locust to our understanding of insect neuropeptides and neurohormones

Abstract

The genomes of the migratory locust Locusta migratoria and the termite Zootermopsis nevadensis were mined for the presence of genes encoding neuropeptides, neurohormones, and their G-protein coupled receptors (GPCRs). Both species have retained a larger number of neuropeptide and neuropeptide GPCRs than the better known holometabolous insect species, while other genes that in holometabolous species appear to have a single transcript produce two different precursors in the locust, the termite or both. Thus, the recently discovered CNMa neuropeptide gene has two transcripts predicted to produce two structurally different CNMa peptides in the termite, while the locust produces two different myosuppressin peptides in the same fashion. Both these species also have a calcitonin gene, which is different from the gene encoding the calcitonin-like insect diuretic hormone. This gene produces two types of calcitonins, calcitonins A and B. It is also present in Lepidoptera and Coleoptera and some Diptera, but absent from mosquitoes and Drosophila. However, in holometabolous insect species, only the B transcript is produced. Their putative receptors were also identified. In contrast, Locusta has a highly unusual gene that codes for a salivation stimulatory peptide. The Locusta genes for neuroparsin and vasopressin are particularly interesting. The neuroparsin gene produces five different transcripts, of which only one codes for the neurohormone identified from the corpora cardiaca. The other four transcripts code for neuroparsin-like proteins, which lack four amino acid residues, and that for that reason we called neoneuroparsins. The number of transcripts for the neoneuroparsins is about 200 times larger than the number of neuroparsin transcripts. The first exon and the putative promoter of the vasopressin genes, of which there are about seven copies in the genome, is very well-conserved, but the remainder of these genes is not. The relevance of these findings is discussed.

Molecular characterization and expression profiles of neuropeptide precursors in the migratory locust

“…Combination of the whole genome and various transcriptome has improved the sequences of 23 neuropeptide precursor genes reported in a previous prediction (Veenstra, 2014). In fact, the numbers of neuropeptide precursor genes and their products may be even larger because some Locustaspecific neuropeptide genes cannot be identified by homolog searching.…”

“…Larger precursors of these signaling messengers are produced mainly in neurons and endocrine cells, after which they are cleaved and modified into mature peptides, then secreted into the extracellular parts (Veenstra, 2000). Alternative splicing often occurs in neuropeptide precursor genes to produce more mature peptides, thereby strongly enhancing neuropeptide diversity (Dircksen et al, 2011;Veenstra, 2014). Mature peptides bind to specific membrane receptors and stimulate intracellular molecules, thus performing their biological functions (Xu et al, 2010).…”

“…Apparently, discovery of all precursor genes was difficult because of their small size and low transcription levels without the entire genome information. Until recently, dozens of genes encoding neuropeptide precursors have been reported (Veenstra, 2014) on the basis of the contig sequences of L. migratoria genome . Nevertheless, many of these neuropeptide genes are incomplete with missing 5 0 or 3 0 encoding sequences in the prediction, which should be further confirmed and corrected.…”

DINeR — A Database for Insect Neuropeptide Research

“…Although kinin plays a similar role, this functionality has been lost in Rhodnius prolixus (Bhatt et al, 2014;Te Brugge et al, 2002) while kinin signalling seems to have been lost from the order Coleoptera (Halberg et al, 2015). Although Coast and Schooley (2011) proposed changing the neuropeptide name from DH31 to calcitonin-like diuretic hormone (CT-DH), a new insect neuropeptide family was discovered (Veenstra, 2014) which showed a higher similarity to vertebrate calcitonin and was thus named Calcitonin. To avoid unnecessary confusion, the historical neuropeptide name DH31 (Furuya et al, 2000) would be more appropriate and is therefore used in DINeR.…”

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“…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 (Veenstra, 2014 (Fig. 1), while immunoreactive material was completely absent from the central nervous 110 system.…”