title: Evolution of neuropeptides in non-pterygote hexapods.
abstract: BACKGROUND
  Neuropeptides are key players in information transfer and act as important regulators of development, growth, metabolism, and reproduction within multi-cellular animal organisms (Metazoa). These short protein-like substances show a high degree of structural variability and are recognized as the most diverse group of messenger molecules. We used transcriptome sequences from the 1KITE (1K Insect Transcriptome Evolution) project to search for neuropeptide coding sequences in 24 species from the non-pterygote hexapod lineages Protura (coneheads), Collembola (springtails), Diplura (two-pronged bristletails), Archaeognatha (jumping bristletails), and Zygentoma (silverfish and firebrats), which are often referred to as "basal" hexapods. Phylogenetically, Protura, Collembola, Diplura, and Archaeognatha are currently placed between Remipedia and Pterygota (winged insects); Zygentoma is the sistergroup of Pterygota. The Remipedia are assumed to be among the closest relatives of all hexapods and belong to the crustaceans.
  
  
  RESULTS
  We identified neuropeptide precursor sequences within whole-body transcriptome data from these five hexapod groups and complemented this dataset with homologous sequences from three crustaceans (including Daphnia pulex), three myriapods, and the fruit fly Drosophila melanogaster. Our results indicate that the reported loss of several neuropeptide genes in a number of winged insects, particularly holometabolous insects, is a trend that has occurred within Pterygota. The neuropeptide precursor sequences of the non-pterygote hexapods show numerous amino acid substitutions, gene duplications, variants following alternative splicing, and numbers of paracopies. Nevertheless, most of these features fall within the range of variation known from pterygote insects. However, the capa/pyrokinin genes of non-pterygote hexapods provide an interesting example of rapid evolution, including duplication of a neuropeptide gene encoding different ligands.
  
  
  CONCLUSIONS
  Our findings delineate a basic pattern of neuropeptide sequences that existed before lineage-specific developments occurred during the evolution of pterygote insects.
authors.affiliation: Institute for Zoology, Functional Peptidomics Group, University of Cologne, D-50674, Cologne, Germany. christian.derst@t-online.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Derst
authors.affiliation: Department of Zoology, Stockholm University, S-10691, Stockholm, Sweden. hdircksen@freenet.de.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Dircksen
authors.affiliation: Center for Molecular Biodiversity Research, Zoological Research Museum A. Koenig, D-53113, Bonn, Germany. meusemann@gmx.de.|Australian National Insect Collection, CSIRO National Research Collections Australia, Acton, ACT, 2601, Canberra, Australia. meusemann@gmx.de.
authors.forename: Karen
authors.initials: K
authors.lastname: Meusemann
authors.affiliation: China National GeneBank, BGI-Shenzhen, Shenzhen, Guangdong Province, 518083, China. xinzhou@genomics.org.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.affiliation: China National GeneBank, BGI-Shenzhen, Shenzhen, Guangdong Province, 518083, China. liushanlin@genomics.cn.
authors.forename: Shanlin
authors.initials: S
authors.lastname: Liu
authors.affiliation: Institute for Zoology, Functional Peptidomics Group, University of Cologne, D-50674, Cologne, Germany. rpredel@uni-koeln.de.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Predel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001181:Arthropods / Q000145:classification / Q000235:genetics; D019143:Evolution, Molecular; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics*; D007313:Insecta / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D059467:Transcriptome
chemical_list: D019476:Insect Proteins; D009479:Neuropeptides; C079229:pyrokinin