Similarities between decapod and insect neuropeptidomes
- Published
- Accepted
- Subject Areas
- Bioinformatics, Evolutionary Studies, Genomics, Neuroscience, Zoology
- Keywords
- Neuropeptide, androgenic insulin-like peptide, neuroparsin, agatoxin-like peptide, PDH, calcitonin, crustacean female sex hormone, evolution, receptor
- Copyright
- © 2016 Veenstra
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Similarities between decapod and insect neuropeptidomes. PeerJ Preprints 4:e1882v1 https://doi.org/10.7287/peerj.preprints.1882v1
Abstract
Background. Neuropeptides are important regulators of physiological processes and behavior. Although they tend to be generally well conserved, recent results using trancriptome sequencing on decapod crustaceans give the impression of significant differences between species, raising the question whether such differences are real or artefacts. Methods. The BLAST+ program was used to find short reads coding neuropeptides and neurohormons in publicly available short read archives. Such reads were then used to find similar reads in the same archives and the DNA assembly program Trinity was employed to construct contigs encoding the neuropeptide precursors as completely as possible. Results. The seven decapod species analyzed in this fashion, the crabs Eriocheir sinensis, Carcinus maenas and Scylla paramamosain, the shrimp Litopenaeus vannamei, the lobster Homarus americanus, the fresh water prawn Macrobrachium rosenbergii and the crayfish Procambarus clarkii had remarkably similar neuropeptidomes. Although some neuropeptide precursors could not be assembled, in many cases individual reads pertaining to the missing precursors show unambiguously that these neuropeptides are present in these species. In other cases the tissues that express those neuropeptides were not used in the construction of the cDNA libraries. One novel neuropeptide was identified, elongated PDH (pigment dispersing hormone), a variation on PDH that has a two amino acid insertion in its core sequence. Hyrg is another peptide that is ubiquitously present in decapods and is likely a novel neuropeptide precursor. Discussion. Many insect species have lost one or more neuropeptide genes, but apart from elongated PDH and hyrg all other decapod neuropeptides are present in at least some insect species and allatotropin is the only insect neuropeptide missing from decapods. This strong similarity between insect and decapod neuropeptidomes makes it possible to predict the receptors for decapod neuropeptides that have been deorphanized in insects. This includes the androgenic insulin like peptide that seems to be homologous to drosophila insulin-like peptide 8.
Author Comment
This is a preprint submission to PeerJ Preprints.
Supplemental Information
Likely Trinity transcript errors
a: Trinity generated transcript for Eriocheir FMRFamide precursor. b: Trinity generated transcript for Scylla orcokinin precursor (Bao et al., 2015). Note that both these contigs have long internal repeats that would be highly unlikely to occur by chance and, hence, suggests that they are artefacts. Nucleotide sequences highlighted in yellow are perfect repeats. c: Alignment of several crab orcokinin precursors, providing additional arguments to suggest that the second Scylla orcokinin precursor contig is indeed an artefact.
Alignment of decapod agatoxin-like pepitdes
Note that both the sequence of the peptide as well as the presence of various transcripts of this gene are well conserved within decapods.
Sequence alignment of arthropod calcitonins
Note that the decapod calcitonins (highlighted in yellow) fit nicely in with the other arthropod calcitonins and are hence easily classified as being either A or B.
Identification of some peptide sequences found by mass spectrometry in Decapods
a: Deduced amino acid sequence of Carcinus cryptocyanin. Note that the sequence deduced from mass spectrometry data (KIFEPLRDKN) is different from the subsequence in cryptocyanin. However, this may well be an error in sequence interpretation from the mass spectrometry data as KIFEPLRENN and KIFEPLRDKN have very similar theoretical masses (1259.41 and 1259.45 respectively, versus 1259.71 found). This does not explain the KIFEPLVA peptide sequence, but given its similarity to the other peptides, it seems plausible also related to a cryptocyanin. b: Deduced amino acid sequence of Homarus thymosin containing the subsequence DLPKVDTALK found by mass spectrometry. c: Deduced amino acid sequence of Homarus histone 2A containing the subsequence AVLLPKKTEKK found by mass spectrometry. The peptide sequence KPKTEKK is perhaps PKTEKK, and if so, it would also be present in histone 2A. D: Homarus cytoplasmic type 3 actin containing the subsequence LRVAPEEHPVLL found by mass spectrometry. All protein sequences were deduced from SRAs from the respective species using Trinity. Peptides identified within these protein sequences are highlighted.