Molecular cloning of a cDNA encoding molt-inhibiting hormone of the crab, Cancer magister

Molecular cloning of crustacean hyperglycemic hormone (CHH) family members (CHH, molt-inhibiting hormone and mandibular organ-inhibiting hormone) and their expression levels in the Jonah crab, Cancer borealis

The crustacean hyperglycemic hormone (CHH) neuropeptide family has multiple functions in the regulation of hemolymph glucose levels, molting, ion, and water balance and reproduction. In crab species, three neuroendocrine tissues: the eyestalk ganglia (medulla terminalis X-organ and -sinus gland = ES), the pericardial organ (PO), and guts synthesize a tissue-specific isoforms of CHH neuropeptides. Recently the presence of the mandibular organ-inhibiting hormone (MOIH) was reported in the stomatogastric nervous system (STNS) that regulates the rhythmic muscle movements in esophagus, cardiac sac, gastric and pyloric ports of the foregut. In this study, we aimed to determine the presence of a tissue-specific CHH isoform in the Jonah crab, Cancer borealis using PCR with degenerate primers and 5', 3' rapid amplification of cDNA ends (RACE) in the ES. PO, and STNS. The analysis of CHH sequences shows that C. borealis has one type of CHH isoform, unlike other crab species. We also isolated the cDNA sequence of molt-inhibiting hormone (MIH) in the ES and MOIH in the ES and STNS. The presence of CHH, MOIH and MIH in the sinus gland of adult females and males is confirmed by using a dot-blot assay with the putative peaks collected from RP-HPLC and anti-Cancer sera for CHH, MIH, and MOIH. The present of crustacean female sex hormone (CFSH) in the sinus gland of adult females was examined with a dot-blot assay with anti-Callinectes CFSH serum. Levels of CHH, MOIH, and MIH in the sinus gland and their expressions in the eyestalk ganglia are estimated in the adult males, where CHH is the predominant form among these neuropeptides.

Effects of temperature on survival, moulting, and expression of neuropeptide and mTOR signalling genes in juvenile Dungeness crab (Metacarcinus magister)

Mechanistic target of rapamymcin (mTOR) is a highly conserved protein kinase that controls cellular protein synthesis and energy homeostasis. We hypothesize that mTOR integrates intrinsic signals (moulting hormones) and extrinsic signals (thermal stress) to regulate moulting and growth in decapod crustaceans. The effects of temperature on survival, moulting and mRNA levels of mTOR signalling genes (Mm-Rheb, Mm-mTOR, Mm-AMPKα, Mm-S6K and Mm-AKT) and neuropeptides (Mm-CHH and Mm-MIH) were quantified in juvenile Metacarcinus magister Crabs at different moult stages (12, 19 or 26 days postmoult) were transferred from ambient temperature (∼15°C) to temperatures between 5 and 30°C for up to 14 days. Survival was 97-100% from 5 to 20°C, but none survived at 25 or 30°C. Moult stage progression accelerated from 5 to 15°C, but did not accelerate further at 20°C. In eyestalk ganglia, Mm-Rheb, Mm-AMPKα and Mm-AKT mRNA levels decreased with increasing temperatures. Mm-MIH and Mm-CHH mRNA levels were lowest in the eyestalk ganglia of mid-premoult animals at 20°C. In the Y-organ, Mm-Rheb mRNA levels decreased with increasing temperature and increased during premoult, and were positively correlated with haemolymph ecdysteroid titre. In the heart, moult stage had no effect on mTOR signalling gene mRNA levels; only Mm-Rheb, Mm-S6K and Mm-mTOR mRNA levels were higher in intermoult animals at 10°C. These data suggest that temperature compensation of neuropeptide and mTOR signalling gene expression in the eyestalk ganglia and Y-organ contributes to regulate moulting in the 10 to 20°C range. The limited warm compensation in the heart may contribute to mortality at temperatures above 20°C.

Identification of molt-inhibiting hormone and ecdysteroid receptor cDNA sequences in Gammarus pulex, and variations after endocrine disruptor exposures

In amphipods, growth, development and reproduction are mediated by the molt, which is a hormonally controlled process and which, therefore, could be impacted by endocrine disruption compounds (EDC). The molt process is controlled by both X-organ (XO) and Y-organ (YO) through a variety of hormones and receptors including the molt-inhibiting hormone (MIH) and the ecdysteroid receptor (EcR). However, although many studies were devoted to characterize MIH and EcR in crustaceans, only few works evaluated their variations under EDCs exposures. Consequently, the present work aimed to characterize MIH and EcR genes of the amphipod Gammarus pulex, as well as to study their relative expression variations after exposure to four EDCs, proved in vertebrates: ethinylestradiol (estrogen), 4-hydroxytamoxifen (anti-estrogen), 17α-methyltestosterone (androgen) and cyproterone acetate (anti-androgen). PCR amplification allowed to obtain 204 bp length and 255 bp length fragments, encoding for partial sequences of 68 amino acids and 85 amino acids, which correspond to EcR and MIH, respectively, and which are highly conserved in crustacean species. Results highlighted MIH and EcR expressions mainly in G. pulex head, which is the localization of XO and YO. Moreover, irrespective of the EDC exposure, increases of MIH and EcR relative expressions were observed, as it was observed after the exposure to 20-hydroxyecdysone (20HE), the natural molt hormone, used as positive control. Therefore, it appeared that tested EDCs behaved like 20HE, suggesting that their effects could occur through the ecdysteroids pathways, and so impact the molt process of G. pulex on the long term. Finally, the present study is a first step in the possibility of using MIH and EcR relative expressions as biomarkers of exposure for EDCs risk assessment. However additional studies must first be carried out to better characterize and understand their variations, and also better predicted consequences for the exposed amphipods.

Characterization, expression patterns of molt-inhibiting hormone gene of Macrobrachium nipponense and its roles in molting and growth

The oriental river prawn, Macrobrachium nipponense, is an important commercial aquaculture resource in China. In order to overwinter, M. nipponense displays decreased physiological activity and less consumption of energy. Sudden warming would trigger molting and cause an extensive death, resulting in huge economic losses. Therefore, it is of great practical significance to study the molting mechanism of oriental river prawns. Molt-inhibiting hormone gene (MIH) plays a major role in regulating molting in crustaceans. In this study, a full length MIH cDNA of M. nipponense (Mn-MIH) was cloned from the eyestalk. The total length of the Mn-MIH was 925 bp, encoding a protein of 119 amino acids. Tissue distribution analysis showed that Mn-MIH was highly expressed in the eyestalk, and that it had relatively low expression in gill, ovary, and abdominal ganglion. Mn-MIH was detected in all developmental stages, and changed regularly in line with the molting cycle of the embryo and larva. Mn-MIH varied in response to the molting cycle, suggesting that Mn-MIH negatively regulates ecdysteroidogenesis. Mn-MIH inhibition by RNAi resulted in a significant acceleration of molting cycles in both males and females, confirming the inhibitory role of MIH in molting. After long-term RNAi males, but not females had significant weight gain, confirming that Mn-MIH plays an important role in growth of M. nipponense. Our work contributes to a better understanding of the role of Mn-MIH in crustacean molting and growth.

Functional analysis of the promoter of the molt-inhibiting hormone (mih) gene in mud crab Scylla paramamosain

In this study, the 5'-flanking region of molt-inhibiting hormone (MIH) gene was cloned by Tail-PCR. It is 2024 bp starting from the translation initiation site, and 1818 bp starting from the predicted transcription start site. Forecast analysis results by the bioinformatics software showed that the transcription start site is located at 207 bp upstream of the start codon ATG, and TATA box is located at 240 bp upstream of the start codon ATG. Potential transcription factor binding sites include Sp1, NF-1, Oct-1, Sox-2, RAP1, and so on. There are two CpG islands, located at -25- +183 bp and -1451- -1316 bp respectively. The transfection results of luciferase reporter constructs showed that the core promoter region was located in the fragment -308 bp to -26 bp. NF-kappaB and RAP1 were essential for mih basal transcriptional activity. There are three kinds of polymorphism CA in the 5'-flanking sequence, and they can influence mih promoter activity. These findings provide a genetic foundation of the further research of mih transcription regulation.

Moult-inhibiting fusion protein augments while polyclonal antisera attenuate moult stages and duration in Penaeus monodon

Moulting in crustaceans is regulated by moult-inhibiting hormone (MIH) of the CHH family neuropeptides. The inhibitory functions of MIH have pivotal roles in growth and reproduction of Penaeus monodon. In this study, we report the expression of a thioredoxin-fused mature MIH I protein (mf-PmMIH I) of P. monodon in a bacterial system and its use as antigen to raise polyclonal antiserum (anti-mf-PmMIH I). The mature MIH I gene of 231bp, that codes for 77 amino acids, was cloned into the Escherichia coli thioredoxin gene fusion expression system. The translation expression vector construct (mf-PmMIH I+pET32a+) upon induction produced 29.85kDa mature MIH I fusion protein (mf-PmMIH I). The purified fusion protein was used as exogenous MIH I and as antigen to raise polyclonal antisera. When fusion protein (mf-PmMIH I) was injected into D2 and D3 stages of juvenile shrimp, the moult cycle duration was extended significantly to 16.67±1.03 and 14.67±1.03days respectively compared to that of 11.67±1.03days in controls. Moult duration was further reduced to 8.33±0.82days when polyclonal antiserum (anti-mf-PmMIH I - 1:500 dilutions) was injected. Anti-mf-PmMIH I immunolocalized MIH I producing neurosecretory cells in the eyestalk of P. monodon. In short, the present manuscript reports an innovative means of moult regulation in P. monodon with thioredoxin fused MIH I and antisera developed.

Stimulation of molt by RNA interference of the molt-inhibiting hormone in the crayfish Cherax quadricarinatus

In crustaceans, molting is known to be under the control of neuropeptide hormones synthesized and secreted from the eyestalk ganglia. While the role of molt-inhibiting hormone (MIH) in regulating molting has been described in several species using classical methods, an in vivo specific MIH targeted manipulation has not been described yet. In the present study, an MIH cDNA was isolated and sequenced from the eyestalk ganglia of the Australian freshwater red claw crayfish Cherax quadricarinatus (Cq) by 5' and 3' RACE. We analyzed the putative Cq-MIH based on sequence homology, a three dimensional structure model and transcript's tissue specificity. We further examined the involvement of Cq-MIH in the control of molt in the crayfish through RNAi by in vivo injections of Cq-MIH double-stranded RNA, which resulted in, similarly to eyestalk ablation, acceleration of molt cycles. This acceleration was reflected by a significant reduction (up to 32%) in molt interval and an increased rate in molt mineralization index (MMI), which correlated with the induction of ecdysteroid hormones compared to control. Altogether, this study provides a proof of function for the involvement of the Cq-MIH gene in molt regulation in the crayfish.

Molt-inhibiting hormone from Chinese mitten crab (Eriocheir sinensis): Cloning, tissue expression and effects of recombinant peptide on ecdysteroid secretion of YOs

Molt-inhibiting hormone (MIH), a member of the crustacean hyperglycemic hormone (CHH) family, inhibits the synthesis of ecdysteroid in Y-organ (YO) and plays a significant role in the regulation of molting and growth of crustaceans. A complete cDNA sequence encoding MIH (Ers-MIH, GenBank Accession No.: DQ341280) was cloned from eyestalk of Chinese mitten crab (Eriocheir sinensis) by 5' and 3' RACEs and PCR cloning. The full-length cDNA consists of 1457 bp with a 330 bp open reading frame, encoding 110 amino acids, containing a 75 amino acid mature peptide. The deduced amino acid sequence contains a typical CHH domain. Transcripts of Ers-MIH mRNA were detected in eyestalk by Northern blotting. The production of purified recombinant Ers-MIH (rErs-MIH) expressed in Escherichia coli was 0.3g/L. The LC-ESI-MS analysis showed that two peptide fragments of the recombinant protein were identical to the deduced amino acid sequence of Ers-MIH. By in vitro assay on E. sinensis YOs, a cGMP mediated suppression of rErs-MIH on ecdysteroidogenesis could be observed. Accumulation of cGMP in YOs showed a concentration-dependent manner within 0.01-1 nmol/mL of rErs-MIH; ecdysteroid secretion was inhibited significantly at the range of 0.01-100 nmol/mL rErs-MIH; furthermore, a significant inhibition effect on ecdysteroid releasing was shown when cGMP analog (8-Br-cGMP) concentration rose up to 100 nmol/mL. This study would facilitate to investigate the roles of MIH in molt cycle regulation.

Crustacean hyperglycemic hormone from the tropical land crab, Gecarcinus lateralis: cloning, isoforms, and tissue expression

Crustacean hyperglycemic hormone (CHH) regulates carbohydrate metabolism, molting, and ion and water transport. cDNAs encoding four CHH isoforms (designated EG-CHH-A, -B, -C, and -D) were cloned from eyestalk ganglia (EG) from land crab, Gecarcinus lateralis. The isoforms differed in the 3' region of the open reading frame and/or the length of the 3' untranslated region. All encoded essentially identical preprohormones containing a 28-amino acid (aa) signal peptide, a 42-aa precursor related peptide and a 72-aa mature CHH. All deduced aa sequences had the six cysteines, two arginines, one aspartate, one phenylalanine, and one arginine originally identified as characteristic of this neuropeptide family. There was a single aa difference between the EG-CHH-D mature hormone and the other three isoforms. The EG-CHH isoforms were expressed in EG, hindgut, and thoracic ganglion. A fifth CHH isoform, designated pericardial organ (PO)-CHH, was similar to the PO-CHH isoform described in green crab, Carcinus maenas. It was expressed in hindgut and testis, but not in eyestalk ganglia; its expression in PO was not determined. The deduced aa sequence of the PO-CHH was identical to that of the EG-CHH isoforms through aa #40 of the mature peptide. The divergent aa sequence between positions #41 and #73 was encoded by an insertion of a 111-bp sequence absent in EG-CHH cDNAs. The data suggest that EG-CHH and PO-CHH isoforms are generated by alternative splicing of at least two CHH genes.

Molecular characterization and gene expression pattern of two putative molt-inhibiting hormones from Litopenaeus vannamei

Two cDNA sequences (Liv-MIH1 and Liv-MIH2) were cloned from the eyestalk ganglia of the white shrimp Litopenaeus vannamei. The conceptually translated peptide precursors consist of a mature peptide (77 residues for Liv-MIH1, 75 residues for Liv-MIH2), preceded by a 28-residue signal peptide. Both mature peptides share highest sequence identity with other known MIHs, and contain several conserved residues that have been proposed to be functionally critical for MIH activity. Analysis of genomic sequences reveals that both genes are organized in a 3 exon/2 intron manner, with the same sites of intron insertion. The transcripts of Liv-MIH1 and Liv-MIH2 were detected exclusively in the eyestalk, but not in other neural and non-neural tissues examined. Phylogenetic analysis indicates that Liv-MIH1 and Liv-MIH2 cluster with the type II peptides that are considered as penaeid MIH. In addition, a quantitative real-time polymerase chain reaction (PCR) assay was developed and validated for the quantification of gene expression of Liv-MIH1 and Liv-MIH2. Transcript levels for both genes remained constant through stages A - D(1') (ranges of relative expression levels are 97.9+/-2.9 to 104.5+/-8.9% for Liv-MIH1, and 85.6+/-6.7 to 104.7+/-10.8% for Liv-MIH2), and declined afterwards, reaching a lowest level during stage D(2)D(3) (40.6+/-0.4% for Liv-MIH1, and 48.5+/-3.2% for Liv-MIH2). These significant decreases in the transcript levels correspond to a significant increase in hemolymph ecdysteroid titers at stage D(2)D(3). These results clearly indicate that Liv-MIH1 and Liv-MIH2 are type II peptides of the crustacean hyperglycemic hormone family and most likely function as MIHs in the white shrimp. They are discussed with regard to the presence of multiple MIHs and possible functional divergence of type II peptides in Penaeidae, as well as endocrine regulation of crustacean molting.

Molt-inhibiting hormone from the tropical land crab, Gecarcinus lateralis: cloning, tissue expression, and expression of biologically active recombinant peptide in yeast

Molt-inhibiting hormone (MIH), a member of the crustacean hyperglycemic neuropeptide hormone family, inhibits ecdysteroidogenesis in the molting gland or Y-organ (YO). A cDNA encoding MIH of the land crab (Gel-MIH) was cloned from eyestalk ganglia (EG) by a combination of reverse transcriptase polymerase chain reaction (RT-PCR) and 3'- and 5'-rapid amplification of cDNA ends (RACE). The cDNA (1.4 kb) encoded MIH prohormone containing a 35 amino acid signal peptide and a 78 amino acid mature peptide. The mature peptide had the six cysteines, one glycine, two arginines, one aspartate, one phenylalanine, and one asparagine in identical positions in the highly conserved sequence characteristic of other crustacean MIHs. Gel-MIH was expressed only in the EG, as determined by RT-PCR; it was not detected in Y-organ, heart, integument, gill, testis, ovary, hepatopancreas, thoracic ganglion, or skeletal muscle. A cDNA encoding the mature peptide was used to express recombinant MIH (rMIH) using a yeast (Pichia pastoris) expression system. Two constructs were designed to yield either a mature MIH fusion protein with a c-myc epitope and histidine (His) tag at the carboxyl terminus or an untagged mature protein without the c-myc and His sequences. Immunoreactive peptides were detected in Western blots of the cell culture media with both MIH constructs, indicating secretion of the processed rMIH into the medium. Culture media containing the untagged mature peptide significantly inhibited ecdysteroid secretion by YOs from land crab and green crab (Carcinus maenas) cultured in vitro, indicating that the Gel-rMIH was biologically active.

Members of the crustacean hyperglycemic hormone (CHH) peptide family are differentially distributed both between and within the neuroendocrine organs of Cancer crabs: implications for differential release and pleiotropic function

The crustacean hyperglycemic hormone (CHH) family of peptides includes CHH, moult-inhibiting hormone (MIH) and mandibular organ-inhibiting hormone (MOIH). In the crab Cancer pagurus, isoforms of these peptides, as well as CHH precursor-related peptide (CPRP), have been identified in the X-organ-sinus gland (XO-SG) system. Using peptides isolated from the C. pagurus SG, antibodies to each family member and CPRP were generated. These sera were then used to map the distributions and co-localization patterns of these peptides in the neuroendocrine organs of seven Cancer species: Cancer antennarius, Cancer anthonyi, Cancer borealis, Cancer gracilis, Cancer irroratus, Cancer magister and Cancer productus. In addition to the XO-SG, the pericardial organ (PO) and two other neuroendocrine sites contained within the stomatogastric nervous system, the anterior cardiac plexus (ACP) and the anterior commissural organ (ACO), were studied. In all species, the peptides were found to be differentially distributed between the neuroendocrine sites in conserved patterns: i.e. CHH, CPRP, MIH and MOIH in the XO-SG, CHH, CPRP and MOIH in the PO, and MOIH in the ACP (no immunolabeling was found in the ACO). Moreover, in C. productus (and probably in all species), the peptides present in the XO-SG and PO were differentially distributed between the neurons within each of these neuroendocrine organs (e.g. CHH and CPRP in one set of XO somata with MIH and MOIH co-localized in a different set of cell bodies). Taken collectively, the differential distributions of CHH family members and CPRP both between and within the neuroendocrine organs of crabs of the genus Cancer suggests that each of these peptides may be released into the circulatory system in response to varied, tissue-specific cues and that the PO- and/or ACP-derived isoforms may possess functions distinct from those classically ascribed to their release from the SG.

Characterization of an additional molt inhibiting hormone-like neuropeptide from the shrimp Metapenaeus ensis

We have identified a second form of the type-II neuropeptide encoding a molt inhibiting hormone-like (MeeMIH-B) neuropeptide. MeeMIH-B showed only a 70% amino acid identity to the MIH-A (formerly MIH) isolated from the same species, suggesting a possible different function of the deduced neuropeptide. Like other neuropeptide members of the CHH family, the MIH-B gene consists of three exons separated by two introns. The levels of MIH-B mRNA transcript in the eyestalk decrease in the initial phase of gonad maturation and increase towards the end of maturation. The drop in MIH-B level suggests an inhibitory role for this neuropeptide in the initiation of vitellogenesis. MIH-B transcripts can also be detected in the brain, thoracic ganglion and ventral nerve cord. Together with the CHH-B peptide that we have previously described, this is the second peptide of the CHH family that can also be identified in the ventral nerve cord and in the XOSG complex. A recombinant MIH-B was produced and a polyclonal antibody against rMIH-B was subsequently generated. Specific anti-rMIH-B antiserum recognized the presence of MIH-B in the sinus gland, X-organs, as well as a giant neuron of the ventral nerve cord. Injection of rMIH-B delayed the molting cycle of the maturing female. Taken together, the results of this study suggest that a drop in MIH-B level may be required for the delay in the molting of the maturing females.

Cloning of precursors for two MIH/VIH-related peptides in the prawn, Macrobrachium rosenbergii

Two cDNA clones (634 and 1366 bp) encoding MIH/VIH (molt-inhibiting hormone/vitellogenesis-inhibiting hormone)-related peptides were isolated and sequenced from a Macrobrachium rosenbergii eyestalk ganglia cDNA library. The clones contain a 360 and 339 bp open-reading frame, and their conceptually translated peptides consist of a 41 and 34 amino acid signal peptide, respectively, and a 78 amino acid residue mature peptide hormone. The amino acid sequences of the peptides exhibit higher identities with other known MIHs and VIH (44-69%) than with CHHs (28-33%). This is the first report describing the cloning and sequencing of two MIH/VIH-related peptides in a single crustacean species. Transcription of these mRNAs was detected in the eyestalk ganglia, but not in the thoracic ganglia, hepatopancreas, gut, gill, heart, or muscle.

Characterization of cDNA encoding molt-inhibiting hormone of the crab, Cancer pagurus; expression of MIH in non-X-organ tissues

Synthesis of ecdysteroids (molting hormones) by crustacean Y-organs is regulated by a neuropeptide, molt-inhibiting hormone (MIH), produced in eyestalk neural ganglia. We report here the molecular cloning of a cDNA encoding MIH of the edible crab, Cancer pagurus. Full-length MIH cDNA was obtained by using reverse transcription-polymerase chain reaction (RT-PCR) with degenerate oligonucleotides based upon the amino acid sequence of MIH, in conjunction with 5'- and 3'-RACE. Full-length clones of MIH cDNA were obtained that encoded a 35 amino acid putative signal peptide and the mature 78 amino acid peptide. Of various tissues examined by Northern blot analysis, the X-organ was the sole major site of expression of the MIH gene. However, a nested-PCR approach using non-degenerate MIH-specific primers indicated the presence of MIH transcripts in other tissues. Southern blot analysis indicated a simple gene arrangement with at least two copies of the MIH gene in the genome of C. pagurus. Additional Southern blotting experiments detected MIH-hybridizing bands in another Cancer species, Cancer antennarius and another crab species, Carcinus maenas.

Molt-inhibiting hormone immunoreactive neurons in the eyestalk neuroendocrine system of the blue crab, Callinectes sapidus

The production of ecdysteroid molting hormones by crustacean Y-organs is negatively regulated by a neuropeptide, molt-inhibiting hormone. It is generally agreed that molt-inhibiting hormone is produced and released by the eyestalk neuroendocrine system. In the present study, immunocytochemical methods were used to detect molt-inhibiting hormone immunoreactive neurons in eyestalk ganglia of the blue crab, Callinectes sapidus. The primary antiserum used was generated against molt-inhibiting hormone of the green shore crab, Carcinus maenas. A preliminary Western blot analysis indicated the antiserum binds molt-inhibiting hormone of Callinectes sapidus. Using confocal and conventional immunofluorescence microscopy, molt-inhibiting hormone immunoreactivity was visualized in whole mounts and thin sections of Callinectes sapidus eyestalk ganglia. Immunoreactivity was detected in 15-25 neurosecretory cell bodies in the medulla terminalis X-organ, their associated axons and collateral branches, and their axon terminals in the neurohemal sinus gland. The cellular organization of molt-inhibiting hormone immunoreactive neurons in blue crabs is generally similar to that reported for other crab species. The combined results suggest the cellular structure of the molt-inhibiting hormone neuroendocrine system is highly conserved among brachyurans.

Characterization and sequence elucidation of a novel peptide with molt-inhibiting activity from the South African spiny lobster, Jasus lalandii

We have isolated a peptide from extracts of sinus glands from a South African spiny lobster species, Jasus lalandii, by high-performance liquid chromatography (HPLC) and identified it as a putative molt-inhibiting hormone (MIH) by (i) an in vitro assay with J. lalandii Y-organs to measure the inhibition of ecdysteroid synthesis and (ii) an immunoassay using antiserum raised against MIH of the edible crab. The MIH of J. lalandii has 74 amino acid residues, a molecular mass of 9006 Da, a free N-terminus and an amidated C-terminus. The full primary sequence has been obtained from sequencing various digest fragments (tryptic, endoproteinase Asp-N, cyanogen bromide) of the unreduced (native) peptide: RFTFDCPGMMGQRYLYEQVEQVCDDCYNLYREEKIAVNCRENCFLNSWFTVCLQATMREHETPRFDIWR SIILKA-NH(2). Structural comparisons with other peptides show that the J. lalandii MIH belongs to the peptide family which includes the crustacean hyperglycemic hormone, molt-inhibiting hormone and vitellogenesis-inhibiting hormone (cHH/MIH/VIH). This novel peptide has 36-43% sequence identity to putative MIHs from other decapod crustaceans and 32-34% identity to the two cHH peptides previously identified in this spiny lobster species. This is the first report of a peptide with MIH activity in the Palinuridae infraorder.

Clustering of mandibular organ-inhibiting hormone and moult-inhibiting hormone genes in the crab, Cancer pagurus, and implications for regulation of expression

Development and reproduction of crustaceans is regulated by a combination of neuropeptide hormones, ecdysteroids (moulting hormones) and the isoprenoid, methyl farnesoate (MF), the unepoxidised analogue of insect juvenile hormone-III (JH-III). MF and the ecdysteroids are respectively synthesised under the negative control of the sinus gland-derived mandibular organ-inhibiting hormones (MO-IHs) and moult-inhibiting hormone (MIH) that are produced in eyestalk neural ganglia. Previous work has demonstrated the existence of two isoforms of MO-IH, called MO-IH-1 and -2, that differ by a single amino acid in the mature peptide and one in the putative signal peptide. To study the structural organisation of the crab MIH and MO-IH genes, a genomic DNA library was constructed from DNA of an individual female crab and screened with both MO-IH and MIH probes. The results from genomic Southern blot analysis and library screening indicated that the Cancer pagurus genome contains at least two copies of the MIH gene and three copies of the MO-IH genes. Upon screening, two types of overlapping genomic clone were isolated. Each member of one type of genomic clone contains a single copy of each of the convergently transcribed MO-IH-1 and MIH genes clustered within 6.5kb. The other type contains only the MO-IH-2 gene, which is not closely linked to an MIH gene. There are three exons and two introns in all MIH and MO-IH genes analysed. The exon-intron boundary of the crab MIH and MO-IH genes follows Chambon's rule (GT-AG) for the splice donor and acceptor sites. The first intron occurs within the signal peptide region and the second intron occurs in the coding region of the mature peptide. Sequence analysis of upstream regions of MO-IH and MIH genes showed that they contained promoter elements with characteristics similar to other eukaryotic genes. These included sequences with high degrees of similarity to the arthropod initiator, TATA box and cAMP response element binding protein. Additionally, putative CF1/USP and Broad Complex Z2 transcription factor elements were found in the upstream regions of MIH and MO-IH genes respectively. The implications of the presence of the latter two putative transcription factor binding-elements for control of expression of MIH and MO-IH genes is discussed. Phylogenetic analysis and gene organisation show that MO-IH and MIH genes are closely related. Their relationship suggests that they represent an example of evolutionary divergence of crustacean hormones.

Profiling the peptides in two neurohemal organs, the sinus gland and lateral nervous plexus of terrestrial isopods (Crustacea), by mass spectrometry

A comparison was made of the ultrastructure of two neurohemal organs: the sinus gland and the lateral nervous plexus of the Oniscidea (Crustacea). Reverse-phase chromatography clearly showed that the two organs contain different neuropeptides. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry proved to be an efficient tool for detecting the molecules stored in a single freshly dissected neurohemal organ. All the results combined lead us to emphasize that the sinus gland of Oniscidea stores mainly crustacean hyperglycemic hormone (CHH) and vitellogenin-inhibiting hormone; these two hormones were not characterized in the lateral nervous plexus (LNP). Smaller peptides and other molecules of the CHH family might be released by the LNP in the vicinity of the Y-organ (the ecdysteroid-producing gland).