Molecular cloning, tissue distribution, and ontogeny of gonadotropin-releasing hormone III gene (GnRH-III) in half-smooth tongue sole (Cynoglossus semilaevis).

Gonadotropin-releasing hormone (GnRH) is a neuropeptide that plays a vital role in hypothalamus-pituitary-gonad (HPG) axis. In the present study, the GnRH-III gene was isolated from half-smooth tongue sole (Cynoglossus semilaevis). In the 1160 bp genomic sequence, four exons, three introns, and 5'-/3'-flanking sequences were identified. The putative peptide was 92 residues long, including a putative signal peptide containing 23 amino acids, the GnRH decapeptide, a proteolytic cleavage site of three amino acids and a GnRH associated peptide of 56 amino acids. The overall amino acid sequence of C. semilaevis GnRH-III (csGnRH-III) was highly conserved with other teleost GnRH-III genes. Phylogenetic analysis showed the evolutionary relationships of csGnRH-III with other known GnRH genes. A 320 bp promoter sequence of the csGnRH-III was also analyzed, and several potential regulatory motifs were identified which were conserved in the GnRH promoters of other teleosts. Quantitative real-time PCR analysis indicated csGnRH-III was expressed only in brain and gonads. In C. semilaevis, the csGnRH-III transcript was maternally deposited and appeared to be developmentally regulated during embryogenesis and early larval development. Comparing sequence and expression patterns of csGnRH-III with other teleosts GnRH-IIIs suggested that the main function of GnRH-III might be conserved in teleosts.

A novel member of the adipokinetic peptide family in a "living fossil", the ice crawler Galloisiana yuasai, is the first identified neuropeptide from the order Grylloblattodea.

This is the first report on the structural identity of a neuropeptide of the insect order Grylloblattodea. A peptide was isolated and sequenced from the retrocerebral corpora cardiaca-corpora allata complex of the ice crawler, Galloisiana yuasai. The sequence of the peptide was deduced from the multiple MS(N) electrospray mass data as that of an octapeptide: pGlu-Val-Asn-Phe-Ser-Pro-Thr-Trp amide. The retention time on reversed-phase HPLC and the CID MS(2) mass spectra of a synthetic peptide with the same primary structure were exactly the same as of the natural peptide. The sequence represents a novel peptide of the adipokinetic hormone family which contains presently 50 members. The primary structure differs in only one position to a few previously discovered AKHs. A scenario is outlined that makes it likely that the most recently discovered insect order, the Mantophasmatodea, and the Grylloblattodea are closely related.

Peptides of the adipokinetic hormone/red pigment-concentrating hormone family: a new take on biodiversity.

Peptides of the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family in insects are involved in the mobilization of stored macromolecules in the fat body by activating glycogen phosphorylase or triacylglycerol lipase to increase the levels of circulating metabolites (trehalose, diacylglycerols, and also proline) during periods of intense muscular activity. Here I review the biodiversity of these peptides and outline how the 47 known bioanalogues are distributed between the different insect orders and in which species they occur.

Water scorpions (Heteroptera, Nepidae) and giant water bugs (Heteroptera, Belostomatidae): sources of new members of the adipokinetic hormone/red pigment-concentrating hormone family.

Two novel octapeptide members of the AKH/RPCH family have been identified from the corpora cardiaca (CC) of two species of water bugs. The giant water bug Lethocerus indicus (family: Belostomatidae) contains a peptide code-named Letin-AKH with the sequence pGlu-Val-Asn-Phe-Ser-Pro-Tyr-Trp amide, and the water scorpion Nepa cinerea (family: Nepidae) has the peptide code-named Nepci-AKH with the sequence pGlu-Leu/Ile-Asn-Phe-Ser-Ser-Gly-Trp amide. The sequences were deduced from the multiple MS(N) electrospray mass data from crude CC extracts. Synthetic peptides were made and co-elution on reversed-phase high performance liquid chromatography (RP-HPLC) with the natural peptide from crude gland extract confirmed the accuracy of the deduced sequence for Letin-AKH and demonstrated that Nepci-AKH contains a Leu residue at position 2 and not an Ile residue. A previously characterized member of the AKH/RPCH family was identified in the stick water scorpion Ranatra linearis by mass spectrometry: Grybi-AKH (pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp amide) has the same mass (919 Da) as Nepci-AKH and differs in two positions from Nepci-AKH (residues 2 and 6). The apparent function of the peptides is to achieve lipid mobilization in the species under investigation; indications for this came from conspecific bioassays using the appropriate synthetic peptides for injecting into the insects. This function is very likely linked to dispersal flight metabolism of water bugs. Swimming activity in N. cinerea also results in an increase in lipid concentration in the hemolymph.