Chromactivating hormones of Pandalus Borealis. Isolation and purification of the 'red-pigment-concentrating hormone'

De novo assembly transcriptome analysis reveals the genes associated with body color formation in the freshwater ornamental shrimps Neocaridina denticulate sinensis

The body color of Neocaridina denticulate sinensis is a compelling phenotypic trait, in which a cascade of carotenoid metabolic processes plays an important role. The study was conducted to compare the transcriptome of cephalothoraxes among three pigmentation phenotypes (red, blue, and chocolate) of N. denticulate sinensis. The purpose of this study was to explore the candidate genes associated with different colors of N. denticulate sinensis. Nine cDNA libraries in three groups were constructed from the cephalothoraxes of shrimps. After assembly, 75022 unigenes were obtained in total with an average length of 1026 bp and N50 length of 1876 bp. There were 45977, 25284, 23605, 21913 unigenes annotated in the Nr, Swissprot, KOG, and KEGG databases, respectively. Differential expression analysis revealed that there were 829, 554, and 3194 differentially expressed genes (DEGs) in RD vs BL, RD vs CH, and BL vs CH, respectively. These DEGs may play roles in the absorption, transport, and metabolism of carotenoids. We also emphasized that electron transfer across the inner mitochondrial membrane (IMM) was a key process in pigment metabolism. In addition, a total of 6328 simple sequence repeats (SSRs) were also detected in N. denticulate sinensis. The results laid a solid foundation for further research on the molecular mechanism of integument pigmentation in the crustacean and contributed to developing more attractive aquatic animals.

Assessment and comparison of putative amine receptor complement/diversity in the brain and eyestalk ganglia of the lobster, Homarus americanus

In decapods, dopamine, octopamine, serotonin, and histamine function as locally released/hormonally delivered modulators of physiology/behavior. Although the functional roles played by amines in decapods have been examined extensively, little is known about the identity/diversity of their amine receptors. Recently, a Homarus americanus mixed nervous system transcriptome was used to identify putative neuronal amine receptors in this species. While many receptors were identified, some were fragmentary, and no evidence of splice/other variants was found. Here, the previously predicted proteins were used to search brain- and eyestalk ganglia-specific transcriptomes to assess/compare amine receptor complements in these portions of the lobster nervous system. All previously identified receptors were reidentified from the brain and/or eyestalk ganglia transcriptomes, i.e., dopamine alpha-1, beta-1, and alpha-2 (Homam-DAα2R) receptors, octopamine alpha (Homam-OctαR), beta-1, beta-2, beta-3, beta-4, and octopamine-tyramine (Homam-OTR-I) receptors, serotonin type-1A, type-1B (Homam-5HTR1B), type-2B, and type-7 receptors; and histamine type-1 (Homam-HA1R), type-2, type-3, and type-4 receptors. For many previously partial proteins, full-length receptors were deduced from brain and/or eyestalk ganglia transcripts, i.e., Homam-DAα2R, Homam-OctαR, Homam-OTR-I, and Homam-5HTR1B. In addition, novel dopamine/ecdysteroid, octopamine alpha-2, and OTR receptors were discovered, the latter, Homam-OTR-II, being a putative paralog of Homam-OTR-I. Finally, evidence for splice/other variants was found for many receptors, including evidence for some being assembly-specific, e.g., a brain-specific Homam-OTR-I variant and an eyestalk ganglia-specific Homam-HA1R variant. To increase confidence in the transcriptome-derived sequences, a subset of receptors was cloned using RT-PCR. These data complement/augment those reported previously, providing a more complete picture of amine receptor complement/diversity in the lobster nervous system.

The evolution and nomenclature of GnRH-type and corazonin-type neuropeptide signaling systems

Gonadotropin-releasing hormone (GnRH) was first discovered in mammals on account of its effect in triggering pituitary release of gonadotropins and the importance of this discovery was recognized forty years ago in the award of the 1977 Nobel Prize for Physiology or Medicine. Investigation of the evolution of GnRH revealed that GnRH-type signaling systems occur throughout the chordates, including agnathans (e.g. lampreys) and urochordates (e.g. sea squirts). Furthermore, the discovery that adipokinetic hormone (AKH) is the ligand for a GnRH-type receptor in the arthropod Drosophila melanogaster provided evidence of the antiquity of GnRH-type signaling. However, the occurrence of other AKH-like peptides in arthropods, which include corazonin and AKH/corazonin-related peptide (ACP), has complicated efforts to reconstruct the evolutionary history of this family of related neuropeptides. Genome/transcriptome sequencing has revealed that both GnRH-type receptors and corazonin-type receptors occur in lophotrochozoan protostomes (annelids, mollusks) and in deuterostomian invertebrates (cephalochordates, hemichordates, echinoderms). Furthermore, peptides that act as ligands for GnRH-type and corazonin-type receptors have been identified in mollusks. However, what has been lacking is experimental evidence that distinct GnRH-type and corazonin-type peptide-receptor signaling pathways occur in deuterostomes. Importantly, we recently reported the identification of two neuropeptides that act as ligands for either a GnRH-type receptor or a corazonin-type receptor in an echinoderm species - the common European starfish Asterias rubens. Discovery of distinct GnRH-type and corazonin-type signaling pathways in this deuterostomian invertebrate has demonstrated for the first time that the evolutionarily origin of these paralogous systems can be traced to the common ancestor of protostomes and deuterostomes. Furthermore, lineage-specific losses of corazonin signaling (in vertebrates, urochordates and nematodes) and duplication of the GnRH signaling system in arthropods (giving rise to the AKH and ACP signaling systems) and quadruplication of the GnRH signaling system in vertebrates (followed by lineage-specific losses or duplications) accounts for the phylogenetic distribution of GnRH/corazonin-type peptide-receptor pathways in extant animals. Informed by these new insights, here we review the history of research on the evolution of GnRH/corazonin-type neuropeptide signaling. Furthermore, we propose a standardized nomenclature for GnRH/corazonin-type neuropeptides wherein peptides are either named "GnRH" or "corazonin", with the exception of the paralogous GnRH-type peptides that have arisen by gene duplication in the arthropod lineage and which are referred to as "AKH" (or red pigment concentrating hormone, "RCPH", in crustaceans) and "ACP".

Prediction of a peptidome for the western tarnished plant bug Lygus hesperus

Many strategies for controlling insect pests require an understanding of their hormonal signaling agents, peptides being the largest and most diverse single class of these molecules. Lygus hesperus is a pest species of particular concern, as it is responsible for significant damage to a wide variety of commercially important plant crops. At present, little is known about the peptide hormones of L. hesperus. Here, transcriptomic data were used to predict a peptidome for L. hesperus. Fifty-three L. hesperus transcripts encoding peptide precursors were identified, with a subset amplified by PCR for sequence verification. The proteins deduced from these transcripts allowed for the prediction of a 119-sequence peptidome for L. hesperus. The predicted peptides include isoforms of allatostatin A, allatostatin B (AST-B), allatostatin C, allatotropin, bursicon, CCHamide, corazonin, crustacean cardioactive peptide, crustacean hyperglycemic hormone/ion transport peptide, diuretic hormone 31, GSEFLamide, insulin-like peptide, myosuppressin, neuroparsin, neuropeptide F, orcokinin, orcomyotropin, pyrokinin, short neuropeptide F, SIFamide, sulfakinin and tachykinin-related peptide. Of note were several isoforms of AST-B that possess -WX₇Wamide carboxyl-termini rather than the stereotypical -WX₆Wamide (e.g., KWQDMQNPGWamide), an allatotropin ending in -SARGFamide rather than -TARGFamide (GLKNGPLNSARGFamide), a GSEFLamide ending in -GTEFLamide (TVGTEFLamide), several orcokinins with PMDEIDR- rather than NFDEIDR- amino-termini (e.g., PMDEIDRAGFTHFV), and an eight rather than 12 amino acid long isoform of SIFamide (PPFNGSIFamide). Collectively, the L. hesperus peptidome predicted here provides a resource for initiating physiological investigations of peptidergic signaling in this species, including studies directed at the biological control of this agricultural pest.

Functional Characterization of Paralogous Gonadotropin-Releasing Hormone-Type and Corazonin-Type Neuropeptides in an Echinoderm

Homologs of the vertebrate neuropeptide gonadotropin-releasing hormone (GnRH) have been identified in invertebrates, including the insect neuropeptide corazonin (CRZ). Recently, we reported the discovery of GnRH-type and CRZ-type signaling systems in an echinoderm, the starfish Asterias rubens, demonstrating that the evolutionary origin of paralogous GnRH-type and CRZ-type neuropeptides can be traced back to the common ancestor of protostomes and deuterostomes. Here, we have investigated the physiological roles of the GnRH-type (ArGnRH) and the CRZ-type (ArCRZ) neuropeptides in A. rubens, using mRNA in situ hybridization, immunohistochemistry and in vitro pharmacology. ArGnRH precursor (ArGnRHP)-expressing cells and ArGnRH-immunoreactive cells and/or processes are present in the radial nerve cords, circumoral nerve ring, digestive system (e.g., cardiac stomach and pyloric stomach), body wall-associated muscle (apical muscle), and appendages (tube feet, terminal tentacle). The general distribution of ArCRZ precursor (ArCRZP)-expressing cells is similar to that of ArGnRHP, but with specific local differences. For example, cells expressing ArGnRHP are present in both the ectoneural and hyponeural regions of the radial nerve cords and circumoral nerve ring, whereas cells expressing ArCRZP were only observed in the ectoneural region. In vitro pharmacological experiments revealed that both ArGnRH and ArCRZ cause contraction of cardiac stomach, apical muscle, and tube foot preparations. However, ArGnRH was more potent/effective than ArCRZ as a contractant of the cardiac stomach, whereas ArCRZ was more potent/effective than ArGnRH as a contractant of the apical muscle. These findings demonstrate that both ArGnRH and ArCRZ are myoexcitatory neuropeptides in starfish, but differences in their expression patterns and pharmacological activities are indicative of distinct physiological roles. This is the first study to investigate the physiological roles of both GnRH-type and CRZ-type neuropeptides in a deuterostome, providing new insights into the evolution and comparative physiology of these paralogous neuropeptide signaling systems in the Bilateria.

Pigment Translocation in Caridean Shrimp Chromatophores: Receptor Type, Signal Transduction, Second Messengers, and Cross Talk Among Multiple Signaling Cascades

Pigment aggregation in shrimp chromatophores is triggered by red pigment concentrating hormone (RPCH), a neurosecretory peptide whose plasma membrane receptor may be a G-protein coupled receptor (GPCR). While RPCH binding activates the Ca²⁺ /cGMP signaling cascades, a role for cyclic AMP (cAMP) in pigment aggregation is obscure, as are the steps governing Ca²⁺ release from the smooth endoplasmic reticulum (SER). A role for the antagonistic neuropeptide, pigment dispersing homone (α-PDH) is also unclear. In red, ovarian chromatophores from the freshwater shrimp Macrobrachium olfersi, we show that a G-protein antagonist (AntPG) strongly inhibits RPCH-triggered pigment aggregation, suggesting that RPCH binds to a GPCR, activating an inhibitory G-protein. Decreasing cAMP levels may cue pigment aggregation, since cytosolic cAMP titers, when augmented by cholera toxin, forskolin or vinpocentine, completely or partially impair pigment aggregation. Triggering opposing Ca²⁺ /cGMP and cAMP cascades by simultaneous perfusion with lipid-soluble cyclic nucleotide analogs induces a "tug-of-war" response, pigments aggregating in some chromatosomes with unpredictable, oscillatory movements in others. Inhibition of cAMP-dependent protein kinase accelerates aggregation and reduces dispersion velocities, suggesting a role in phosphorylation events, possibly regulating SER Ca²⁺ release and pigment aggregation. The second messengers IP₃ and cADPR do not stimulate SER Ca²⁺ release. α-PDH does not sustain pigment dispersion, suggesting that pigment translocation in caridean chromatophores may be regulated solely by RPCH, since PDH is not required. We propose a working hypothesis to further unravel key steps in the mechanisms of pigment translocation within crustacean chromatophores that have remained obscure for nearly a century.

The mechanism of regulation of ovarian maturation by red pigment concentrating hormone in the mud crab Scylla paramamosain

In this study a full-length cDNA (Sp-RPCH) was cloned from the eyestalk ganglia of the mud crab Scylla paramamosain. Sp-RPCH is 660 base pairs in length and its open reading frame encodes a precursor that is predicted to be processed into a 25-residue signal peptide, a mature red pigment concentrating hormone (RPCH, an octapeptide), and a 75-residue precursor-related peptide. Phylogenetic analysis indicates that it clusters with other crustacean RPCHs and belongs to the adipokinetic hormone/RPCH peptide superfamily. Sp-RPCH gene expression was detected, using an end-point polymerase chain reaction (PCR), not only in the eyestalk ganglia but also in the brain and thoracic ganglia. Quantified using a real-time PCR, Sp-RPCH gene expression levels in the three tissues fluctuated along a cycle of ovarian maturation, with the levels progressively increased from stages I to IV, after which the expression levels decreased (although they remained significantly higher than stage I levels) when the ovary reached the mature stage (stage V). It was demonstrated using a patch clamp analysis that synthetic RPCH was able to evoke a Ca(2+) current in dissociated brain neurons and synthetic RPCH significantly increased the mean oocyte diameter of the ovarian tissues co-cultured with the eyestalk ganglia, brain, or thoracic ganglia; the stimulatory effect of RPCH was absent when the nervous tissues were not included in the ovarian incubation. Animals administrated with RPCH had significantly higher levels of gonad-somatic index, hepatopancreas-somatic index, and vitellogenin gene expression, when compared to control animals receiving a saline injection. The combined results clearly show that RPCH is involved in ovarian maturation in the mud crab; the stimulatory effects of RPCH are likely mediated by its actions on the release from the nervous tissues of factor(s) that directly regulate vitellogenesis in the ovary and hepatopancreas.

Neuropeptide discovery in Eucyclops serrulatus (Crustacea, Copepoda): in silico prediction of the first peptidome for a member of the Cyclopoida

Crustaceans of the subclass Copepoda are key components of essentially all aquatic ecosystems as they serve both as the primary consumers of phytoplankton and/or as major food sources for a wide variety of higher-level consumers. The dominant group of copepods in most freshwater ecosystems is the Cyclopoida; members of this order are routinely used as environmental indicators, and some predatory species are used for the biological control of disease-causing mosquitoes. Given their ecological and disease control importance, it is surprising that little is known about endocrine control in cyclopoids. Here, as part of an ongoing effort to identify and characterize the neurochemical signaling systems of members of the Copepoda, the extant transcriptome shotgun assembly for Eucyclops serrulatus, a member of the Cyclopoida, was mined for transcripts encoding putative peptide hormone-encoding transcripts. Via queries using known arthropod pre/preprohormone sequences, primarily ones from other copepod species, 36 E. serrulatus peptide-encoding transcripts were identified. The proteins deduced from these sequences allowed for the prediction of 160 unique mature neuropeptides, including the first copepod isoform of pigment dispersing hormone, as well as isoforms of adipokinetic hormone-corazonin-like peptide, allatostatin A, allatostatin B, allatostatin C, allatotropin, crustacean hyperglycemic hormone, diuretic hormone 31, DXXRLamide, FLRFamide, FXGGXamide, GSEFLamide, insulin-like peptide, intocin, leucokinin, myosuppressin, neuroparsin, neuropeptide F and tachykinin-related peptide. These peptides are currently the only ones known from any member of the Cyclopoida, and as such, provide a new resource for investigating peptidergic signaling in this important copepod order.

Identification of the first neuropeptides from the Amphipoda (Arthropoda, Crustacea)

Despite being used as models in the field of ecotoxicology, including use in studies of endocrine disruption, little is known about the hormonal systems of amphipods, particularly their peptidergic signaling systems. Here, transcriptome shotgun assembly (TSA) sequences were used to predict the structures of the first neuropeptides from members of this crustacean order. Using a well-established workflow, BLAST searches of the extant amphipod TSA data were conducted for putative peptide-encoding transcripts. The pre/preprohormones deduced from the identified TSA sequences were then used to predict the mature structures of amphipod neuropeptides. In total, 43 putative peptide-encoding transcripts were identified from three amphipods, Echinogammarus veneris, Hyalella azteca and Melita plumulosa. Collectively, 139 distinct mature peptides (110 from E. veneris alone) were predicted from these TSA sequences. The identified peptides included members of the adipokinetic hormone/red pigment concentrating hormone, allatostatin A, allatostatin B, allatostatin C, bursicon α, bursicon β, crustacean hyperglycemic hormone, diuretic hormone 31, FLRFamide, molt-inhibiting hormone, myosuppressin, neuroparsin, neuropeptide F, orcokinin, pigment dispersing hormone (PDH), proctolin, RYamide, SIFamide, sulfakinin and tachykinin-related peptide families. Of particular note were the identifications of orcokinins possessing SFDEIDR- rather than the typical NFDEIDR- amino-termini, e.g. SFDEINRSNFGFN, a carboxyl-terminally amidated orcokinin, i.e. SFDEINRSNFGFSamide, PDHs longer than the stereotypical 18 amino acids, e.g. NSELLNTLLGSKSLAALRAAamide, and a 13 rather than 12 amino acid long SIFamide, i.e. GPYRKPPFNGSIFamide. These data not only provide the first descriptions of native amphipod neuropeptides, but also represent a new resource for initiating investigations of peptidergic signaling in the Amphipoda.

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.

Crustacean neuroendocrine systems and their signaling agents

Decapod crustaceans have long served as important models for the study of neuroendocrine signaling. For example, the process of neurosecretion was first formally demonstrated by using a member of this order. In this review, the major decapod neuroendocrine organs are described, as are their phylogenetic conservation and neurochemistry. In addition, recent advances in crustacean neurohormone discovery and tissue mapping are discussed, as are several recent advances in our understanding of hormonal control in this group of animals.

Crustacean neuropeptides

Crustaceans have long been used for peptide research. For example, the process of neurosecretion was first formally demonstrated in the crustacean X-organ-sinus gland system, and the first fully characterized invertebrate neuropeptide was from a shrimp. Moreover, the crustacean stomatogastric and cardiac nervous systems have long served as models for understanding the general principles governing neural circuit functioning, including modulation by peptides. Here, we review the basic biology of crustacean neuropeptides, discuss methodologies currently driving their discovery, provide an overview of the known families, and summarize recent data on their control of physiology and behavior.

Cyclic guanosine monophosphate signaling cascade mediates pigment aggregation in freshwater shrimp chromatophores

The cell signaling cascades that mediate pigment movements in crustacean chromatophores are not yet well established, although Ca(2+) and cyclic nucleotide second messengers are involved. Here, we examine the participation of cyclic guanosine monophosphate (cGMP) in pigment aggregation triggered by red pigment concentrating hormone (RPCH) in the red ovarian chromatophores of freshwater shrimp. In Ca(2+)-containing (5.5 mmol l(-1)) saline, 10 micromol l(-1) dibutyryl cGMP alone produced complete pigment aggregation with the same time course ( approximately 20 min) and peak velocity ( approximately 17 microm/min) as 10(-8) mol l(-1) RPCH; however, in Ca(2+)-free saline (9 x 10(-11) mol l(-1) Ca(2+)), db-cGMP was without effect. The soluble guanylyl cyclase (GC-S) activators sodium nitroprusside (SNP, 0.5 micromol l(-1)) and 3-morpholinosydnonimine (SIN-1, 100 micromol l(-1)) induced moderate aggregation by themselves ( approximately 35%-40%) but did not affect RPCH-triggered aggregation. The GC-S inhibitors zinc protoporphyrin IX (ZnPP-XI, 30 micromol l(-1)) and 6-anilino-5,8-quinolinedione (LY83583, 10 micromol l(-1)) partially inhibited RPCH-triggered aggregation by approximately 35%. Escherichia coli heat-stable enterotoxin (STa, 1 micromol l(-1)), a membrane-receptor guanylyl cyclase stimulator, did not induce or affect RPCH-triggered aggregation. We propose that the binding of RPCH to an unknown membrane-receptor type activates a Ca(2+)-dependent signaling cascade coupled via cytosolic guanylyl cyclase and cGMP to protein kinase G-phosphorylated proteins that regulate aggregation-associated, cytoskeletal molecular motor activity. This is a further example of a cGMP signaling cascade mediating the effect of a crustacean X-organ neurosecretory peptide.

Hormone complement of theCancer productus sinus gland and pericardial organ: An anatomical and mass spectrometric investigation

In crustaceans, circulating hormones influence many physiological processes. Two neuroendocrine organs, the sinus gland (SG) and the pericardial organ (PO), are the sources of many of these compounds. As a first step in determining the roles played by hemolymph-borne agents in the crab Cancer productus, we characterized the hormone complement of its SG and PO. We show via transmission electron microscopy that the nerve terminals making up each site possess dense-core and/or electron-lucent vesicles, suggesting diverse complements of bioactive molecules for both structures. By using immunohistochemistry, we show that small molecule transmitters, amines and peptides, are among the hormones present in these tissues, with many differentially distributed between the two sites (e.g., serotonin in the PO but not the SG). With several mass spectrometric (MS) methods, we identified many of the peptides responsible for the immunolabeling and surveyed the SG and PO for peptides for which no antibodies exist. By using MS, we characterized 39 known peptides [e.g., beta-pigment-dispersing hormone (beta-PDH), crustacean cardioactive peptide, and red pigment-concentrating hormone] and de novo sequenced 23 novel ones (e.g., a new beta-PDH isoform and the first B-type allatostatins identified from a non-insect species). Collectively, our results show that diverse and unique complements of hormones, including many previously unknown peptides, are present in the SG and PO of C. productus. Moreover, our study sets the stage for future biochemical and physiological studies of these molecules and ultimately the elucidation of the role(s) they play in hormonal control in C. productus.

Quantitative in vitro assay for crustacean chromatophorotropins and other pigment cell agonists

An in vitro crustacean (freshwater shrimp, Macrobrachium potiuna) erythrophore bioassay for chromatophorotropins and other pigment cell agonists is described. The present assay is a quantitative method that determines the pigment responses with the aid of an ocular micrometer. The pigment granules within the erythrophores are dispersed out into the dendritic processes of the cells when the isolated carapace is placed in physiological solution. This bioassay provides, therefore, a method for measuring the response of the pigment cells to aggregating agents such as pigment concentrating hormone (PCH). This bioassay is sensitive to PCH at a concentration as low as 3 x 10(-12) M. Calcium ionophore A23187 mimics the actions of PCH, but, unlike the hormone, the ionophore-induced pigment aggregation is irreversible after physiological solution rinses. Therefore, chromatophorotropic activities of pigment dispersing agents, such as pigment dispersing hormones (PDH), can be determined on ionophore-treated erythrophores. The potencies of alpha-PDH and beta-PDH show a threefold difference (not significant). Because of its convenience and its ability to make an objective determination of the bidirectional pigment movements within erythrophores, this bioassay is a suitable method for further structure-activity studies of the various chromatophorotropins and their analogs.

The presence of enkephalin-like substances in the eyestalk and brain of the land crab Gecarcinus lateralis

The eyestalk of the land crab, Gecarcinus lateralis, is rich in Met-enkephalin-like materials. Leu-enkephalin, if present, is at a level which is below the sensitivity of our assay. The brain (cerebral ganglion) of this organism contains both Met- and Leu-enkephalin-like materials. Material which was reactive with our Met-enkephalin antibody was also detected in a peak that migrated after Leu-enkephalin. This biochemical study confirms earlier immunohistochemical reports which indicated that opioid substances are present in crustaceans. It also strongly supports the concept that opioid mechanisms are a product of early evolution and further demonstrates that the sequence of the smaller opioid compounds has been conserved.

Opioid potentiated chromatophorotropin regulation of pigment migration in the land crab Gecarcinus lateralis

In Gecarcinus lateralis dopamine treatment results in dispersion of black and concentration of red pigments within chromatophores. These effects of dopamine on the migration of pigments can be blocked by the dopamine antagonist haloperidol. These results strongly indicate the presence of a dopamine receptor mediated system in this organism. Serotonin injections also result in the dispersion of black pigment; however, this effect cannot be blocked by haloperidol. Norepinephrine was found to be without effect on this pigment regulatory system. Injections of crude eyestalk extract results in pigment migration within the chromatophores in both stalked and destalked animals. Injection of the stable methionine enkephalin analog FK 33 824 into the organisms causes no observable effects on the pigment system. However, coinjection with eyestalk extract strongly potentiates the effect of the extract. This potentiation can be completely blocked by the opiate antagonist naloxone, thus indicating that an endogenous opioid system may be part of the overall regulation of pigmentation movement.

Isolation of crustacean erythrophore concentrating hormone from nerve tissue of Homarus americanus

Crustacean erythrophore concentrating hormone (CECH) was isolated from lobster (Homarus americanus) eyestalks by reverse phase high-performance liquid chromatography (rp-hplc). Putative lobster CECH fractions co-chromatographed with commercially available pure CECH on two independent rp-hplc systems, and were positive for activity by bioassay. CECH was detected in eyestalk, but not brain homogenates.

Invertebrate neuropeptide hormones

The development of a long-term research program on the neurosecretory hormones of arthropods is described. The purification and full characterization of the first invertebrate neurohormones, the red pigment-concentrating hormone (RPCH) and the distal retinal pigment hormone (DRPH) demonstrated that they are peptides, an octapeptide and an octadecapeptide, respectively. Physiological function studies with the pure hormones and their synthetic preparations showed that the RPCH acts as a general pigment-concentrating hormone (PCH), and that the DRPH, in addition to its light-adaptive function, also constitutes a general pigment-dispersing hormone (PDH). In the regulation of the color-adaptation of the animals, the two hormones act as antagonists. The chromatophorotropic activities are widely distributed within the arthropod neuroendocrine systems. Purification of the pigment-concentrating activities from the locust corpora cardiaca lead to the isolation and characterization of the first insect neurohormones, the adipokinetic hormones (AKH I and AKH II). These two hormones, AKH I being a decapeptide and AKH II being an octapeptide, are close structural analogs to the crustacean PCH, demonstrating a common evolution of arthropod neurohormones. The hormones of this PCH-family all cross-react, but structure-function studies of the hormones show that quite different parts of their structure are involved in their binding to the various receptors.

Isolation and purification of a neurodepressing hormone from the eyestalk of Procambarus bouvieri (Ortmann)

1. A neurodepressing hormone has been isolated and purified to homogeneity from aqueous extracts of 2000 eyestalks of the Mexican crayfish Procambarus bouvieri (Ortmann). 2. Purification was achieved by gel filtration on Sephadex G-25 and G-15, and preparative paper electrophoresis at four pH valueimately 1200 molecular weight and composed of neutral amino acids. 5. No N-terminal group could be found. From its electrophoretic behavior it is concluded that the C-terminal group is also blocked.

Structure-function studies on red pigment-concentrating hormone, II. The significance of the C-terminal tryptophan amide

The significance of the C-terminal tryptophan residue of the red pigment-concentrating hormone (RPCH: Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH2) regulating the blanching of the crustacean chromatophores has been investigated. RPCH and a number of analogues that differ only in the C-terminal part of the hormone, have been synthesized and assayed for biological activity on the shrimp Leander adspersus. It has been shown that the indole skeleton of tryptophan is an absolute requirement for the biological activity of the hormone. To provide maximum response the tryptophan must be blocked as the amide. The activity of synthetic [Tyr4]RPCH and adipokinetic hormone (AKH) purified from Schistocerca gregaria has been compared with the activity of synthetic RPCH.

Crustacean color-change hormone: amino acid sequence and chemical synthesis

The blanching hormone of the prawn, Pandalus borealis, is pGlu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH(2). Its structure was settled by a combination of mass spectrometry and Edman-dansyl analysis of a thermolysin fragment. Confirmation of the structure was obtained by chemical synthesis from amino acids. This neurosecreted hormone is active in picogram amounts when tested in shrimps.

Silkworm Bombyx mori L.: Nature of Diapause Factor

The diapause factor which is responsible for the induction of embryonic diapause in the silkworm (Bombyx mori L.) was isolated from the heads of female moths. It was extracted with 80 percent ethanol or 80 percent methanol and was heat-stable and not dialyzable. Since the active material was precipitated with ammonium sulfate and lost when incubated with proteolytic enzymes, it is highly probable that the diapause factor is a protein or a complex molecule containing peptide bonds. Molecular sieve techniques revealed two species of the diapause factor. The molecular weight of the smaller species lies between 5,000 and 10,000.