“…The length of galanin is highly conserved across vertebrate evolution at 29 amino acids and previously only H. sapiens galanin was known to exceed this length [84]. Our understanding of galanin receptor function in teleosts is only beginning to emerge [85], therefore, the significance of this substitution is unknown. If A. burtoni galanin receptors are similar to D. rerio galanin receptors, and display affinity for galanin and spexin peptides, then the unusual form of A. burtoni galanin may suggest that there has been pronounced ligand-receptor co-evolution in the GAL/SPXN system in cichlids.Fig.…”
BackgroundCichlid fishes have evolved remarkably diverse reproductive, social, and feeding behaviors. Cell-to-cell signaling molecules, notably neuropeptides and peptide hormones, are known to regulate these behaviors across vertebrates. This class of signaling molecules derives from prohormone genes that have undergone multiple duplications and losses in fishes. Whether and how subfunctionalization, neofunctionalization, or losses of neuropeptides and peptide hormones have contributed to fish behavioral diversity is largely unknown. Information on fish prohormones has been limited and is complicated by the whole genome duplication of the teleost ancestor. We combined bioinformatics, mass spectrometry-enabled peptidomics, and molecular techniques to identify the suite of neuropeptide prohormones and pituitary peptide products in Astatotilapia burtoni, a well-studied member of the diverse African cichlid clade.ResultsUtilizing the A. burtoni genome, we identified 148 prohormone genes, with 21 identified as a single copy and 39 with at least 2 duplicated copies. Retention of prohormone duplicates was therefore 41 %, which is markedly above previous reports for the genome-wide average in teleosts. Beyond the expected whole genome duplication, differences between cichlids and mammals can be attributed to gene loss in tetrapods and additional duplication after divergence. Mass spectrometric analysis of the pituitary identified 620 unique peptide sequences that were matched to 120 unique proteins. Finally, we used in situ hybridization to localize the expression of galanin, a prohormone with exceptional sequence divergence in cichlids, as well as the expression of a proopiomelanocortin, prohormone that has undergone an additional duplication in some bony fish lineages.ConclusionWe characterized the A. burtoni prohormone complement. Two thirds of prohormone families contain duplications either from the teleost whole genome duplication or a more recent duplication. Our bioinformatic and mass spectrometric findings provide information on a major vertebrate clade that will further our understanding of the functional ramifications of these prohormone losses, duplications, and sequence changes across vertebrate evolution. In the context of the cichlid radiation, these findings will also facilitate the exploration of neuropeptide and peptide hormone function in behavioral diversity both within A. burtoni and across cichlid and other fish species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2914-9) contains supplementary material, which is available to authorized users.
“…The length of galanin is highly conserved across vertebrate evolution at 29 amino acids and previously only H. sapiens galanin was known to exceed this length [84]. Our understanding of galanin receptor function in teleosts is only beginning to emerge [85], therefore, the significance of this substitution is unknown. If A. burtoni galanin receptors are similar to D. rerio galanin receptors, and display affinity for galanin and spexin peptides, then the unusual form of A. burtoni galanin may suggest that there has been pronounced ligand-receptor co-evolution in the GAL/SPXN system in cichlids.Fig.…”
BackgroundCichlid fishes have evolved remarkably diverse reproductive, social, and feeding behaviors. Cell-to-cell signaling molecules, notably neuropeptides and peptide hormones, are known to regulate these behaviors across vertebrates. This class of signaling molecules derives from prohormone genes that have undergone multiple duplications and losses in fishes. Whether and how subfunctionalization, neofunctionalization, or losses of neuropeptides and peptide hormones have contributed to fish behavioral diversity is largely unknown. Information on fish prohormones has been limited and is complicated by the whole genome duplication of the teleost ancestor. We combined bioinformatics, mass spectrometry-enabled peptidomics, and molecular techniques to identify the suite of neuropeptide prohormones and pituitary peptide products in Astatotilapia burtoni, a well-studied member of the diverse African cichlid clade.ResultsUtilizing the A. burtoni genome, we identified 148 prohormone genes, with 21 identified as a single copy and 39 with at least 2 duplicated copies. Retention of prohormone duplicates was therefore 41 %, which is markedly above previous reports for the genome-wide average in teleosts. Beyond the expected whole genome duplication, differences between cichlids and mammals can be attributed to gene loss in tetrapods and additional duplication after divergence. Mass spectrometric analysis of the pituitary identified 620 unique peptide sequences that were matched to 120 unique proteins. Finally, we used in situ hybridization to localize the expression of galanin, a prohormone with exceptional sequence divergence in cichlids, as well as the expression of a proopiomelanocortin, prohormone that has undergone an additional duplication in some bony fish lineages.ConclusionWe characterized the A. burtoni prohormone complement. Two thirds of prohormone families contain duplications either from the teleost whole genome duplication or a more recent duplication. Our bioinformatic and mass spectrometric findings provide information on a major vertebrate clade that will further our understanding of the functional ramifications of these prohormone losses, duplications, and sequence changes across vertebrate evolution. In the context of the cichlid radiation, these findings will also facilitate the exploration of neuropeptide and peptide hormone function in behavioral diversity both within A. burtoni and across cichlid and other fish species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2914-9) contains supplementary material, which is available to authorized users.
“…It has been well established that kisspeptins are implicated in the activation of puberty, but peripheral signals coming from the gonads or tissues that reflect the growth/adiposity status of the animal are also thought to be involved (Tena-Sempere et al, 2012). In this respect, Martins et al (2014) demonstrated the importance of the galaninergic system in the brain and testis of European sea bass in translating the signals that lead to testicular maturation; they concluded that this system may play a role in the reproductive function of male European sea bass, most likely as a candidate integrator of different signals to trigger onset of puberty in this species. Our preliminary findings suggest that Kiss1 and/or Gnrh2 could be key molecules capable of providing a reliable biological response to the photoperiodic information received by European sea bass.…”
Section: Possible Regulatory Pathways In the Endocrine Cascadementioning
“…PCR reactions were performed using cDNA synthesized from sea bass larvae total RNA (RNA extraction and cDNA synthesis were performed as reported in Ref. ). For each PCR reaction, 12.5 pmol of each primer, 1.5 m M MgCl 2 , 0.25 m M dNTP, and 1 × Phusion GC PCR buffer were mixed in a final 25 μL reaction volume containing 0.5 unit of Phusion DNA polymerase (Thermo Scientific, US) and 5 μg of cDNA.…”
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