De novo molecular modeling and biophysical characterization of Manduca sexta eclosion hormone

RNA interference of eclosion hormone gene reveals its roles in the control of ecdysis behavior in Heortia vitessoides Moore

Eclosion hormone (EH) is an important neuropeptide that regulates growth and development. This study predicted the EH gene (HvEH) of Heortia vitessoides Moore (Lepidoptera: Crambidae) from the transcriptome database and its expression patterns were determined using quantitative real-time polymerase chain reaction. HvEH was expressed in all developmental stages and especially in the head area. RNA interference-mediated silencing of HvEH (2 μg/individual) with double-stranded HvEH RNA (dsHvEH) was achieved within 48 hr. Abnormal phenotypes appeared in the pupa and adult stages. dsHvEH injection suppressed pupation and eclosion rates. HvEH expression increased upon treatment with 20-hydroxyecdysone but decreased at extreme temperatures. These results suggest that HvEH plays an essential role in ecdysis and wing formation in H. vitessoides.

In silico Neuropeptidome of Female Macrobrachium rosenbergii Based on Transcriptome and Peptide Mining of Eyestalk, Central Nervous System and Ovary

Macrobrachium rosenbergii is the most economically important of the cultured freshwater crustacean species, yet there is currently a deficiency in genomic and transcriptomic information for research requirements. In this study, we present an in silico analysis of neuropeptide genes within the female M. rosenbergii eyestalk, central nervous system, and ovary. We could confidently predict 37 preproneuropeptide transcripts, including those that encode bursicons, crustacean cardioactive peptide, crustacean hyperglycemic hormones, eclosion hormone, pigment-dispersing hormones, diuretic hormones, neuropeptide F, neuroparsins, SIFamide, and sulfakinin. These transcripts are most prominent within the eyestalk and central nervous system. Transcript tissue distribution as determined by reverse transcription-polymerase chain reaction revealed the presence of selected neuropeptide genes of interest mainly in the nervous tissues while others were additionally present in the non-nervous tissues. Liquid chromatography-mass spectrometry analysis of eyestalk peptides confirmed the presence of the crustacean hyperglycemic hormone precursor. This data set provides a strong foundation for further studies into the functional roles of neuropeptides in M. rosenbergii, and will be especially helpful for developing methods to improve crustacean aquaculture.

Prediction of the peptidomes of Tigriopus californicus and Lepeophtheirus salmonis (Copepoda, Crustacea)

Transcriptome mining is a powerful method for crustacean peptide discovery, especially when large sequence datasets are available and an appropriate reference is extant. Recently, a 206,041-sequence transcriptome for the copepod Calanus finmarchicus was mined for peptide-encoding transcripts, with ones for 17 families/subfamilies identified. Here, the deduced Calanus pre/preprohormones were used as templates for peptide discovery in the copepods Tigriopus californicus and Lepeophtheirus salmonis; large transcriptome shotgun assembly datasets are publicly accessible for both species. Sixty-five Tigriopus and 17 Lepeophtheirus transcripts, encompassing 22 and 13 distinct peptide families/subfamilies, respectively, were identified, with the structures of 161 and 70 unique mature peptides predicted from the deduced precursors. The identified peptides included members of the allatostatin A, allatostatin C, bursicon α, bursicon β, CAPA/periviscerokinin/pyrokinin, crustacean cardioactive peptide, crustacean hyperglycemic hormone/ion transport peptide, diuretic hormone 31, FLRFamide, leucokinin, myosuppressin, neuroparsin, neuropeptide F, orcokinin, and tachykinin-related peptide families, most of which possess novel structures, though isoforms from other copepods are known. Of particular note was the discovery of novel isoforms of adipokinetic hormone-corazonin-like peptide, allatotropin, corazonin, eclosion hormone and intocin, peptide families previously unidentified in copepods. In addition, Tigriopus precursors for two previously unknown peptide groups were discovered, one encoding GSEFLamides and the other DXXRLamides; precursors for the novel FXGGXamide family were identified from both Tigriopus and Lepeophtheirus. These data not only greatly expand the catalog of known copepod peptides, but also provide strong foundations for future functional studies of peptidergic signaling in members of this ecologically important crustacean subclass.

Genomics, transcriptomics, and peptidomics of Daphnia pulex neuropeptides and protein hormones

We report 43 novel genes in the water flea Daphnia pulex encoding 73 predicted neuropeptide and protein hormones as partly confirmed by RT-PCR. MALDI-TOF mass spectrometry identified 40 neuropeptides by mass matches and 30 neuropeptides by fragmentation sequencing. Single genes encode adipokinetic hormone, allatostatin-A, allatostatin-B, allatotropin, Ala(7)-CCAP, CCHamide, Arg(7)-corazonin, DENamides, CRF-like (DH52) and calcitonin-like (DH31) diuretic hormones, two ecdysis-triggering hormones, two FIRFamides, one insulin, two alternative splice forms of ion transport peptide (ITP), myosuppressin, neuroparsin, two neuropeptide-F splice forms, three periviscerokinins (but no pyrokinins), pigment dispersing hormone, proctolin, Met(4)-proctolin, short neuropeptide-F, three RYamides, SIFamide, two sulfakinins, and three tachykinins. There are two genes for a preprohormone containing orcomyotropin-like peptides and orcokinins, two genes for N-terminally elongated ITPs, two genes (clustered) for eclosion hormones, two genes (clustered) for bursicons alpha, beta, and two genes (clustered) for glycoproteins GPA2, GPB5, three genes for different allatostatins-C (two of them clustered) and three genes for IGF-related peptides. Detailed comparisons of genes or their products with those from insects and decapod crustaceans revealed that the D. pulex peptides are often closer related to their insect than to their decapod crustacean homologues, confirming that branchiopods, to which Daphnia belongs, are the ancestor group of insects.

Genomics and peptidomics of neuropeptides and protein hormones present in the parasitic wasp Nasonia vitripennis

Neuropeptides and protein hormones constitute a very important group of signaling molecules, regulating central physiological processes such as reproduction, development, and behavior. Using a bioinformatics approach, we screened the recently sequenced genome of the parasitic wasp, Nasonia vitripennis, for the presence of these signaling molecules and annotated 30 precursor genes encoding 51 different mature neuropeptides or protein hormones. Twenty-four of the predicted mature Nasonia neuropeptides could be experimentally confirmed by mass spectrometry. We also discovered a completely novel neuropeptide gene in Nasonia, coding for peptides containing the C-terminal sequence RYamide. This gene has orthologs in nearly all arthropods with a sequenced genome, and its expression in mosquitoes was confirmed by mass spectrometry. No precursor could be identified for N-terminally extended FMRFamides, even though their putative G protein coupled receptor (GPCR) is present in the Nasonia genome. Neither the precursor nor the putative receptor could be identified for allatostatin-B, capa, the glycoprotein hormones GPA2/GPB5, kinin, proctolin, sex peptide, and sulfakinin, arguing that these signaling systems are truly absent in the wasp. Also, antidiuretic factors, allatotropin, and NPLP-like precursors are missing in Nasonia, but here the receptors have not been identified in any insect, so far. Nasonia (Hymenoptera) has the lowest number of neuropeptide precursor genes compared to Drosophila melanogaster, Aedes aegypti (both Diptera), Bombyx mori (Lepidoptera), Tribolium castaneum (Coleoptera), Apis mellifera (Hymenoptera), and Acyrthosiphon pisum (Hemiptera). This lower number of neuropeptide genes might be related to Nasonia's parasitic life.