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At least 1,009 records · Page 56Linked to original sources
PubMed1986

Isolation and characterization of a primitive interleukin-1-like protein from an invertebrate, Asterias forbesi.

Interleukin 1 (IL-1) is the major immunoregulatory molecule produced by macrophages and other related cells. It acts as the molecular orchestrator of nonspecific host defense mechanisms against multifarious insults. In this study we report the characterization of an IL-1-like protein from the starfish Asterias forbesi. IL-1-like activity was found in the coelomocytes of this invertebrate and was also isolated and purified from the coelomic fluid. The coelomocytes were capable of phagocytosing latex particles and were adherent to plastic tissue culture dishes. Starfish IL-1 stimulated murine thymocyte proliferation directly and to a greater degree in the presence of submitogenic concentrations of concanavalin A. Starfish IL-1 also stimulated fibroblast proliferation and fibroblast protein synthesis. It was found to have a Mr of 29,500 and pI values of 7.5, 5.9, and 4.8. Starfish IL-1 activity was inhibited by an antibody to human IL-1. These characteristics suggest starfish IL-1 to be very similar to murine and human IL-1. The similarities to vertebrate IL-1 considered along with the evolutionary position of the starfish suggest that IL-1 is an important, ancient, and functionally conserved molecule.

Animals↗
PubMed1989

Evidence for the involvement of opioid neuropeptides in the adherence and migration of immunocompetent invertebrate hemocytes.

Evidence for the participation of opioid neuropeptides in immunoregulatory activities, especially cellular adherence and migration, has been obtained in representatives of two phyla of invertebrates, the mollusc Mytilus edulis and the insect Leucophaea maderae. The injection of a synthetic analog of [Met]enkephalin [( D-Ala2,Met5]enkephalinamide, DAMA; 10(-6) M) had a stimulatory, naloxone-reversible effect on the directed migration of immunocompetent hemocytes. Incubation of hemolymph in the presence of exogenous or endogenous opioid material significantly enhanced the adherence of hemocytes on albumin-coated slides as demonstrated by use of indirect Zeiss-Zonax reflectance computer analysis. Conversely, hemocyte adherence was markedly reduced by the addition of naloxone (10(-8) M) to the incubation medium, either alone or in combination with DAMA. The antagonistic effects of naloxone on the stimulatory activities of opioids indicate that, like those previously reported in mammals, they are receptor-mediated. The presence of an endogenous [Met]enkephalin-like material was demonstrated in cell-free hemolymph as well as sequestered hemocytes by use of high-pressure liquid chromatography and radioimmunoassay. These results demonstrate that the capacity of immunocytes to release and respond to opioid neuropeptide messengers is not restricted to mammalian organisms but was developed early in the course of evolution.

Animals↗
PubMed1991

Molecular cloning and transformation of cyclodiene resistance in Drosophila: an invertebrate gamma-aminobutyric acid subtype A receptor locus.

Cyclodiene resistance represents 60% of the reported cases of insecticide resistance and is also present in vertebrates. Resistance is due to insensitivity of the cyclodiene/picrotoxinin binding site on the gamma-aminobutyric acid subtype A (GABAA) receptor-chloride ionophore complex. Following isolation of cyclodiene-resistant Drosophila mutants, we report the cloning of the locus conferring resistance via a "chromosomal walk" and rescue of the susceptible phenotype by P-element-mediated germ-line transformation. Amino acid sequence analysis of a cDNA from the locus reveals homology with vertebrate GABAA subunits. To our knowledge, this represents the first cloning of an invertebrate GABA receptor and also allows us to manipulate the resistance status of an insect via germ-line transformation. This gene may be useful as a selectable marker in other insect systems.

Amino Acid Sequence↗
PubMed1991

Invertebrate cytokines: tunicate cell proliferation stimulated by an interleukin 1-like molecule.

Tunicate pharyngeal cells include lymphocyte-like cells and granular amoebocytes. They are involved in the specific allogeneic and phagocytic reactions of tunicates. Little is known about their regulation or control. A tunicate interleukin 1 (IL-1)-like fraction is shown to stimulate the proliferation of these cells in vitro. This fraction, designated tunicate IL-1 beta, was isolated from tunicate hemolymph by gel filtration and chromatofocusing chromatography. Mitogenic responses to tunicate IL-1 beta were dose dependent and could be eliminated rapidly by removing tunicate IL-1 beta from culture medium. A second tunicate hemolymph fraction had no effect on tunicate cell proliferation even though it exhibited IL-1-like activity in a mouse thymocyte proliferation assay. Phytohemagglutin did not act synergistically with either fraction. These data are discussed in terms of the function and evolution of IL-1-like molecules in invertebrates.

Animals↗
PubMed1994

Retroviruses in invertebrates: the gypsy retrotransposon is apparently an infectious retrovirus of Drosophila melanogaster.

Retroviruses are commonly considered to be restricted to vertebrates. However, the genome of many eukaryotes contains mobile sequences known as retrotransposons with long terminal repeats (LTR retrotransposons) or viral retrotransposons, showing similarities with integrated proviruses of retroviruses, such as Ty elements in Saccharomyces cerevisiae, copia-like elements in Drosophila, and endogenous proviruses in vertebrates. The gypsy element of Drosophila melanogaster has LTRs and contains three open reading frames, one of which encodes potential products similar to gag-specific protease, reverse transcriptase, and endonuclease. It is more similar to typical retroviruses than to LTR retrotransposons. We report here experiments showing that gypsy can be transmitted by microinjecting egg plasma from embryos of a strain containing actively transposing gypsy elements into embryos of a strain originally devoid of transposing elements. Horizontal transfer is also observed when individuals of the "empty" stock are raised on medium containing ground pupae of the stock possessing transposing elements. These results suggest that gypsy is an infectious retrovirus and provide evidence that retroviruses also occur in invertebrates.

Animals↗
PubMed1995

A nonpeptide agonist of the invertebrate receptor for SchistoFLRFamide (PDVDHVFLRFamide), a member of a subfamily of insect FMRFamide-related peptides.

We describe a nonpeptide mimetic analog of an invertebrate peptide receptor. Benzethonium chloride (Bztc) is an agonist of the SchistoFLRFamide (PDVDHVFLRFamide) receptors found on locust oviducts. Bztc competitively displaces [125I-labeled Y1]SchistoFLRFamide binding to both high- and low-affinity receptors of membrane preparations. Bztc mimics the physiological effects of SchistoFLRFamide on locust oviduct, by inhibiting myogenic and induced contractions in a dose-dependent manner. Bztc is therefore recognized by the binding and activation regions of the SchistoFLRFamide receptors. This discovery provides a unique opportunity within insects to finally target a peptide receptor for the development of future pest management strategies.

Amino Acid Sequence↗
PubMed1995

Habituation of an invertebrate escape reflex due to modulation by higher centers rather than local events.

Learning is widely thought to result from altered potency of synapses within the neural pathways that mediate the learned behavior. Support for this belief, which pervades current physiological and computational thinking, comes especially from the analysis of cases of simple learning in invertebrates. Here, evidence is presented that in one such case, habituation of crayfish escape, the learning is more due to onset of tonic descending inhibition than to the intrinsic depression of circuit synapses to which it was previously attributed. Thus, the altered performance seems to depend at least as much on events in higher centers as on local plasticity.

Animals↗
PubMed1997

Ultraspiracle: an invertebrate nuclear receptor for juvenile hormones.

Juvenile hormones (JH), a sesquiterpenoid group of ligands that regulate developmental transitions in insects, bind to the nuclear receptor ultraspiracle (USP). In fluorescence-based binding assays, USP protein binds JH III and JH III acid with specificity, adopting for each ligand a different final conformational state. JH III treatment of Saccharomyces cerevisiae expressing a LexA-USP fusion protein stabilizes an oligomeric association containing this protein, as detected by formation of a protein-DNA complex, and induces USP-dependent transcription in a reporter assay. We propose that regulation of morphogenetic transitions in invertebrates involves binding of JH or JH-like structures to USP.

Animals↗
PubMed1997

egl-17 encodes an invertebrate fibroblast growth factor family member required specifically for sex myoblast migration in Caenorhabditis elegans.

The proper guidance of the Caenorhabditis elegans hermaphrodite sex myoblasts (SMs) requires the genes egl-15 and egl-17. egl-15 has been shown to encode the C. elegans orthologue of the fibroblast growth factor receptor (FGFR). Here we clone egl-17 and show it to be a member of the fibroblast growth factor (FGF) family, one of the first functional invertebrate FGFs known. egl-17 shares homology with other FGF members, conserving the key residues required to form the distinctive tertiary structure common to FGFs. Genetic and molecular evidence demonstrates that the SM migration defect seen in egl-17 mutant animals represents complete loss of egl-17 function. While mutations in egl-17 affect only SM migration, mutations in egl-15 can result in larval arrest, scrawny body morphology, and the ability to suppress mutations in clr-1. We propose that EGL-17 (FGF) acts as a ligand for EGL-15 (FGFR) specifically during SM migration and that another ligand(s) activates EGL-15 for its other functions.

Amino Acid Sequence↗
PubMed1998

Phosphorylation of a twitchin-related protein controls catch and calcium sensitivity of force production in invertebrate smooth muscle.

"Catch" is a condition of prolonged, high-force maintenance at resting intracellular Ca2+ concentration ([Ca2+]) and very low energy usage, occurring in invertebrate smooth muscles, including the anterior byssus retractor muscle (ABRM) of Mytilus edulis. Relaxation from catch is rapid on serotonergic nerve stimulation in intact muscles and application of cAMP in permeabilized muscles. This release of catch occurs by protein kinase A-mediated phosphorylation of a high (approximately 600 kDa) molecular mass protein, the regulator of catch. Here, we identify the catch-regulating protein as a homologue of the mini-titin, twitchin, based on (i) a partial cDNA of the purified isolated protein showing 77% amino acid sequence identity to the kinase domain of Aplysia californica twitchin; (ii) a polyclonal antibody to a synthetic peptide in this sequence reacting with the phosphorylated catch-regulating protein band from permeabilized ABRM; and (iii) the similarity of the amino acid composition and molecular weight of the protein to twitchin. In permeabilized ABRM, at all but maximum [Ca2+], phosphorylation of twitchin results in a decreased calcium sensitivity of force production (half-maximum at 2.5 vs. 1.3 microM calcium). At a given submaximal force, with equal numbers of force generators, twitchin phosphorylation increased unloaded shortening velocity approximately 2-fold. These data suggest that aspects of the catch state exist not only at resting [Ca2+], but also at higher submaximal [Ca2+]. The mechanism that gives rise to force maintenance in catch probably operates together, to some extent, with that of cycling myosin crossbridges.

Amino Acid Sequence↗
PubMed1995

Interaction of the hemolytic lectin CEL-III from the marine invertebrate Cucumaria echinata with the erythrocyte membrane.

CEL-III is one of four Ca(2+)-dependent galactose/N-acetylgalactosamine (GalNAc)-binding lectins from the marine invertebrate Cucumaria echinata which exhibits hemolytic activity, especially toward rabbit and human erythrocytes. The hemolytic activity of CEL-III was also Ca(2+)-dependent and was found to be inhibited by galactose or GalNAc-containing carbohydrates, suggesting that the hemolysis was caused by CEL-III binding to specific carbohydrates on the erythrocyte membrane by Ca(2+)-dependent lectin activity, followed by partial destruction of the membrane. The activity of CEL-III was highest at 10 degrees C and decreased markedly with increasing temperature, unlike usual enzymatic reactions. The hemolytic activity of CEL-III increased with increasing pH from neutral to 10, but almost no hemolysis was observed below pH 6.5. Immunoblotting analysis of proteins from the erythrocyte membrane after treatment with CEL-III indicated that CEL-III aggregates were irreversibly bound to the membrane. When erythrocytes were incubated with CEL-III in the presence of dextran with molecular masses greater than 4 kDa, lysis was impeded considerably, while a concomitant release of ATP was detected from these osmotically protected cells. It was found that CEL-III released carboxyfluorescein from artificial globoside-containing lipid vesicles, and it is suggested that CEL-III is a novel pore-forming protein with the characteristics of a Ca(2+)-dependent lectin, which may act as a toxic protein to foreign microorganisms.

Adenosine Triphosphate↗
PubMed1996

Oligomerization of the hemolytic lectin CEL-III from the marine invertebrate Cucumaria echinata induced by the binding of carbohydrate ligands.

The hemolytic lectin CEL-III is a Ca2+-dependent, galactose/GalNAc-specific lectin purified from the marine invertebrate Cucumaria echinata (Holothuroidea). We found that this lectin forms ion-permeable pores in erythrocyte and artificial lipid membranes that have specific carbohydrate ligands on the surface. The hemolytic activity of CEL-III exhibited characteristic pH dependence; activity increased remarkably with pH in the alkaline region, especially above pH 9. When rabbit erythrocyte membrane was examined by immunoblotting using anti-CEL-III antiserum after treatment with CEL-III, the irreversible binding of the CEL-III oligomer increased with pH, indicating that the increase in hemolytic activity at higher pH is associated closely with the amount of oligomer irreversibly bound to the membrane. Surface hydrophobicity of CEL-III, as measured by the fluorescent probe 8-anilino-1-naphthalenesulfonate, increased markedly with the binding of specific ligands such as lactose, lactulose, and N-acetyllactosamine at pH 9-10 in the presence of 1 M NaCl. The enhancement of surface hydrophobicity induced by the binding of carbohydrates was also accompanied by the formation of a CEL-III oligomer, which was found to be the same size on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as the oligomer that formed in CEL-III-treated erythrocyte membranes. Far-UV circular dichroism spectra of CEL-III and the oligomer revealed a definite difference in secondary structure. These data suggest that the binding of CEL-III to specific carbohydrate ligands on the erythrocyte surface induces a conformational change in the protein, leading to the exposure of a hydrophobic region which triggers oligomerization and the irreversible binding of the protein to the membrane.

Animals↗
PubMed1997

Molecular cloning and sequencing of a novel invertebrate intestinal mucin cDNA.

The first invertebrate intestinal mucin, termed insect intestinal mucin (IIM), was recently identified from Trichoplusia ni larvae (Wang, P., and Granados, R. R. (1997) Proc. Natl. Acad. Sci. U. S. A. , in press). We report the cDNA cloning and sequencing of IIM, which is only the second completely sequenced intestinal mucin after human intestinal mucin, MUC2. To clone and sequence the cDNA for IIM, a T. ni larval midgut cDNA expression library was constructed and screened with an anti-IIM antiserum. Two full-length cDNA clones for IIM were identified and sequenced. The deduced proteins from the two cDNA clones contained 807 and 788 amino acid residues, respectively. The structural organization of IIM is similar to that of MUC2, containing a 25-amino acid signal leading sequence and two threonine/proline/alanine-rich tandem repeat domains flanked by cysteine-rich sequences. One tandem repeat domain contained two repeating units, TTTQAP and AATTP, and the other contained one repeating unit, TAAP. The cysteine-rich regions showed potential chitin binding features. By immunolocalization in tissue sections, it was determined that IIM is expressed in midgut tissues. The IIM mRNA is abundant in the midgut tissue, and Northern blot analysis indicated that IIM transcripts were not polydispersed as is found in mammalian mucin transcription.

Amino Acid Sequence↗
PubMed1997

Cloning and tyrosine phosphorylation of a novel invertebrate immunocyte protein containing immunoreceptor tyrosine-based activation motifs.

Immunoreceptor tyrosine-based activation motif (ITAM) plays an important role in signal transduction through mammalian T-cell and B-cell antigen receptors and Fc receptors. The ITAM has been found only in vertebrate immunocytes. Ascidians are intriguing invertebrates from the viewpoint of the evolution of immune systems because they are considered to be ancestors of the vertebrates. We have previously shown that the monoclonal antibody A74 inhibits cellular defense reactions of the ascidian. In the present studies, we found that the A74 antigen protein has two ITAMs and several motifs that are proposed to function in signal transduction. The A74 protein is tyrosine-phosphorylated and associated with other proteins in the initial stages of cellular defense reactions. The ITAMs of the A74 protein are tyrosine-phosphorylated by a c-Src kinase in vitro. The A74 protein provides a key to the understanding of the origin of vertebrate immune systems.

Amino Acid Sequence↗
PubMed2002

Calcium channel structural determinants of synaptic transmission between identified invertebrate neurons.

We report here that unlike what was suggested for many vertebrate neurons, synaptic transmission in Lymnaea stagnalis occurs independent of a physical interaction between presynaptic calcium channels and a functional complement of SNARE proteins. Instead, synaptic transmission in Lymnaea requires the expression of a C-terminal splice variant of the Lymnaea homolog to mammalian N- and P/Q-type calcium channels. We show that the alternately spliced region physically interacts with the scaffolding proteins Mint1 and CASK, and that synaptic transmission is abolished following RNA interference knockdown of CASK or after the injection of peptide sequences designed to disrupt the calcium channel-Mint1 interactions. Our data suggest that Mint1 and CASK may serve to localize the non-L-type channels at the active zone and that synaptic transmission in invertebrate neurons utilizes a mechanism for optimizing calcium entry, which occurs independently of a physical association between calcium channels and SNARE proteins.

Animals↗
PubMed2003

Collagen XXIV, a vertebrate fibrillar collagen with structural features of invertebrate collagens: selective expression in developing cornea and bone.

Tissue-specific assembly of fibers composed of the major collagen types I and II depends in part on the formation of heterotypic fibrils, using the quantitatively minor collagens V and XI. Here we report the identification of a new fibrillar-like collagen chain that is related to the fibrillar alpha1(V), alpha1(XI), and alpha2(XI) collagen polypeptides and which is coexpressed with type I collagen in the developing bone and eye. The new collagen was designated the alpha1(XXIV) chain and consists of a long triple helical domain flanked by typical propeptide-like sequences. The carboxyl propeptide is classic, with 8 conserved cysteine residues. The amino-terminal peptide contains a thrombospodin-N-terminal-like (TSP) motif and a highly charged segment interspersed with several tyrosine residues, like the fibril diameter-regulating collagen chains alpha1(V) and alpha1(XI). However, a short imperfection in the triple helix makes alpha1(XXIV) unique from other chains of the vertebrate fibrillar collagen family. The triple helical interruption and additional select features in both terminal peptides are common to the fibrillar chains of invertebrate organisms. Based on these data, we propose that collagen XXIV is an ancient molecule that may contribute to the regulation of type I collagen fibrillogenesis at specific anatomical locations during fetal development.

Amino Acid Motifs↗
PubMed2004

Protein phosphatase 2B dephosphorylates twitchin, initiating the catch state of invertebrate smooth muscle.

"Catch" is the state where some invertebrate muscles sustain high tension for long periods at low ATP hydrolysis rates. Physiological studies using muscle fibers have not yet fully provided the details of the initiation process of the catch state. The process was extensively studied by using an in vitro reconstitution assay with several phosphatase inhibitors. Actin filaments bound to thick filaments pretreated with the soluble protein fraction of muscle homogenate and Ca2+ (catch treatment) in the presence of MgATP at a low free Ca2+ concentration (the catch state). Catch treatment with > 50 microm okadaic acid, > 1 microm microcystin LR, 1 microm cyclosporin A, 1 microm FK506, or 0.2 mm calcineurin autoinhibitory peptide fragment produced almost no binding of the actin filaments, indicating protein phosphatase 2B (PP2B) was involved. Use of bovine calcineurin (PP2B) and its activator calmodulin instead of the soluble protein fraction initiated the catch state, indicating that only PP2B and calmodulin in the soluble protein fraction are essential for the initiation process. The initiation was reproduced with purified actin, myosin, twitchin, PP2B, and calmodulin. 32P autoradiography showed that only twitchin was dephosphorylated during the catch treatment with either the soluble protein fraction or bovine calcineurin and calmodulin. These results indicate that PP2B directly dephosphorylates twitchin and initiates the catch state and that no other component is required for the initiation process of the catch state.

Adenosine Triphosphate↗
PubMed1988

Antibodies to the conserved cytoplasmic domain of the integrin beta 1 subunit react with proteins in vertebrates, invertebrates, and fungi.

The integrin family of cell surface receptors can be divided into three groups on the basis of their homologous beta subunits: beta 1, beta 2, and beta 3. We have raised an antibody against a synthetic peptide corresponding to the COOH-terminal domain of the chicken integrin beta 1 subunit that reacts with beta subunits from a variety of vertebrates, invertebrates, and fungi, demonstrating strong evolutionary conservation of sequences in this domain. In Drosophila cells, the antibody recognizes integrin alpha beta complexes that appear to be identical with position-specific antigens. Cross-reactive proteins are also detected in Caenorhabditis elegans and Candida albicans. The antiserum is specific for beta 1 subunits and does not recognize other integrin beta subunits in humans. In immunofluorescence analyses of cultured cells, the antibody reacts only with permeabilized cells confirming that this highly conserved COOH-terminal segment is a cytoplasmic domain.

Amino Acid Sequence↗