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At least 613 records · Page 34Linked to original sources
PubMed1987

Invertebrate vasopressin/oxytocin homologs. Characterization of peptides from Conus geographus and Conus straitus venoms.

The vasopressin-oxytocin family of peptides is of very ancient lineage, found in organisms as diverse as hydra and man. Although these peptides have been intensively studied in vertebrates, the presumably more extensive invertebrate series was defined primarily by immunological methods. In this report, we describe the purification and structures of two peptides of the vasopressin-oxytocin family from molluscs ("Conopressins"), which were found in the venom of fish-hunting marine snails of the genus Conus. The biological activity observed when the two snail peptides are injected intracerebrally into mice is very similar to that elicited by the vertebrate neurohypophyseal hormones and presumably reflects their actions upon a common receptor in the brain. The sequences of the purified peptides reveal unique features not found in the vertebrate peptide series, most notably an additional positive charge. These are the first members of the invertebrate series of the vasopressin-oxytocin family to be characterized biochemically. The sequences of these peptides are: from Conus geographus venom, Lys-conopressin-G, Cys-Phe-Ile-Arg-Asn-Cys-Pro-Lys-Gly-NH2; and from Conus striatus venom, Arg-conopressin-S, Cys-Ile-Ile-Arg-Asn-Cys-Pro-Arg-Gly-NH2.

Amino Acid Sequence↗
PubMed1986

Lectin-dependent cell-mediated cytotoxicity in an invertebrate model: Con A does not act as a bridge.

The plant lectin concanavalin A (Con A) has been used in an invertebrate model of lectin-dependent cell-mediated cytotoxicity (LDCC). Macrophage-like cells from the susceptible host snail Biomphalaria glabrata become cytotoxic effectors when they encounter sporocysts of the parasitic trematode Schistosoma mansoni that have been treated with Con A. The sugar alpha-methyl mannoside and rabbit anti-Con A antibodies fail to block this LDCC. Con A is effective only when the target, not the effector cell, has been exposed to it. These results constitute evidence against the molecular bridging hypothesis and support the notion that surface modulation of the target may be the stimulus that provokes cytotoxicity. Results from this invertebrate model are discussed in the context of murine T lymphocyte LDCC.

Animals↗
PubMedDate not supplied

Human lymphocyte receptors detected by invertebrate agglutinins.

A review of recently published work is presented on the nature of the agglutination of human peripheral lymphocytes and cultured lymphoblastoid cells by the hemolymph agglutinins of two arachnoids, the Horsefoot (Limulus polyphemus), alias Horseshoe Crab, and the Saharan Scorpion (Androctonus australis). Microagglutination techniques were utilized to study the specificity of the whole serum and purified agglutinin(s) of Limulus and the whole serum agglutinin(s) of Androctonus. Peripheral human lymphocytes of patients with chronic lymphocytic leukemia (CLL) gave higher agglutination titers and scores than did normal cells, with both species of invertebrate agglutinins. However, human B cells gave higher, although overlapping degrees of agglutination, than T cells. The major cell membrane receptor site for agglutinins of both species was the sialic acid moiety, N-acetyl neuraminic acid. Selected literature on plant and invertebrate agglutinins (lectins) was reviewed. These lectins are underscored as valuable cell membrane probes of surface receptors of human lymphocyte subpopulations.

Agglutinins↗
PubMed1994

The SH2-like Akt homology (AH) domain of c-akt is present in multiple copies in the genome of vertebrate and invertebrate eucaryotes. Cloning and characterization of the Drosophila melanogaster c-akt homolog Dakt1.

The Akt proto-oncogene encodes a serine-threonine protein kinase whose carboxyterminal catalytic domain is closely related to the catalytic domains of all the known members of the protein kinase C (PKC) family. Akt, however, differs from PKC in its N-terminal region which contains a domain related distantly to the SH2 domain of cytoplasmic tyrosine kinases and other signalling proteins, which we have named Akt homology (AH) domain. Low stringency hybridization of a c-akt AH probe to a panel of genomic DNAs from vertebrate and invertebrate eucaryotes detected multiple DNA bands (perhaps multiple genes) in all tested species. Drosophila DNA contains at least three hybridizing DNA bands. One of them was cloned, and found by sequence analysis, to define an Akt related gene (Dakt1). Comparison between the coding regions of c-akt and Dakt1 revealed 64.6% identity at the nucleotide level and 76.5% similarity at the amino acid level. The highest degree of homology was detected in the AH domain (68.3% similarity at the amino acid level) and the catalytic domain (83.3% similarity). Additional sequence comparisons revealed that the amino acid similarity between the catalytic domains of Dkt1 and the three known members of the Drosophila protein kinase C (PKC) family, Dpkc1, Dpkc2 and Dpkc3, is 68%, 63.6% and 67.1%, respectively. Dakt1 was mapped to Drosophila chromosome 3R 89BC. Its expression is subject to developmental regulation with the highest levels detected within the fourth hour of embryonic development. These results confirm that the AH domain of Akt defines new protein families in both vertebrate and invertebrate eucaryotes. The high degree of homology between the catalytic domains of Dkt1 and the three known members of the Drosophila PKC family suggests an evolutionarily conserved functional relationship between the members of the two families.

Amino Acid Sequence↗
PubMed1995

Naltrindole sensitive delta 2 opioid receptor mediates invertebrate immunocyte activation.

Previous studies demonstrated the presence of a delta 2 opioid receptor on human and invertebrate immunocytes. The present study demonstrates that this new binding site regulates invertebrate immunocyte activation. In the present study we note that the select delta antagonist, naltrindole, at a low concentration (10(-11) M), can significantly inhibit DAMA induced activation. Interestingly, the general opioid and opiate antagonist, naloxone, is not effective at this low concentration, further suggesting that the delta 2 opioid receptor mediates opioid immunocyte activation. This conclusion is further supported by the fact that DPDPE and DADLE, known to influence delta 1 activity did not affect immunocyte activation at low concentrations.

Animals↗
PubMedDate not supplied

Comparative studies on different small intestinal oligosaccharidase activities in some vertebrates and invertebrates like molluscs.

Oligosaccharidase activities of the small intestinal mucosal homogenates were measured in vertebrates viz fish, toad, garden-lizard (calotes), pigeon, rat and some invertebrates viz, molluscsa. Maximum activities of the enzymes Lactase, Sucrase and Maltase were found in the mammalian species rat, whereas much less activities were found in the non-mammalian vertebrates among which toad shows the highest values and garden lizard the lowest. Among the invertebrates Pila globosa shows higher values of all the enzymes than Achatina fulica. The results obtained have been discussed in the lights of phylogeny and diet habits.

Amphibians↗
PubMed1987

Demonstration of substances immunologically related to the identified arthropod neuropeptides AKH/RPCH in the CNS of several invertebrate species.

The occurrence of adipokinetic hormone (AKH) and red pigment concentrating hormone (RPCH)-like neuropeptides in the central nervous system of different invertebrate species other than insects was investigated immunocytochemically with polyclonal antisera to N- and C-terminal regions of the AKH molecule. Substances reacting with the C-terminal specific antiserum code 241 were present in neurons of the pond snail, Lymnaea stagnalis, the sowbug Porcellio scaber, the centiped Lithobius forficatus and the crayfish Astacus leptodactylus. Substances revealed by the N-terminal specific antiserum code 433 were demonstrated in the latter two species. The distribution of immunoreactive substances in neuropile areas of several ganglia suggests that these substances act as neurotransmitter/neuromodulator. Their presence in neurohemal organs such as the periphery of the pedal and visceral nerves in the pond snail and in the sinus gland of the crayfish suggests a neurohormonal role in these species.

Animals↗
PubMed2005

Nitric oxide in marine invertebrates: a comparative perspective.

Since the discovery of the biological effects of nitric oxide (NO) more than two decades ago, NO has been identified as an important physiological modulator and a messenger molecule in mammals. Parallel to these studies, evidence that has accumulated in recent years has revealed that the NO signalling pathway is spread throughout the entire phylogenetic scale, being increasingly found in lower organisms, ranging from Chordata to Mollusca. The present review attempts to provide a survey of current knowledge of the genesis and possible roles of NO and the related signalling pathway in marine invertebrates, with special emphasis on Sepia, a choice dictated by the increasing appreciation of cephalopods as most valuable model systems for studies of NO biology and the present expectation for new exciting insights into as yet little explored segments of NO biology.

Animals↗
PubMed2005

Invertebrate central pattern generation moves along.

Central pattern generators (CPGs) are circuits that generate organized and repetitive motor patterns, such as those underlying feeding, locomotion and respiration. We summarize recent work on invertebrate CPGs which has provided new insights into how rhythmic motor patterns are produced and how they are controlled by higher-order command and modulatory interneurons.

Animals↗
PubMed1996

Peptidergic neurohormonal control systems in invertebrates.

The concerted activity of many neuropeptides has been implicated in the neurohormonal control of specific behaviors and various physiological functions in some invertebrate model systems. What are the functional consequences of this neuropeptide multiplicity? The distinct actions of closely related neuropeptides have been detected in molluscs and insects; however, recent work provides examples of systems in which some of the multiple isoforms may be functionally redundant. Groups of functionally distinct neuropeptides encoded by the same gene can be expressed in different neurons by alternative gene splicing or cell-specific post-translational processing; therefore, as shown recently, they can be targeted for release as 'cocktails' to act on specific sets of muscles or neurons. One prominent role of neuropeptides is to modulate the activity of rhythm-generating circuits, as exemplified by recent research on mollusc neural networks, the crab stomatogastric ganglion, and fly circadian pacemakers.

Animals↗
PubMed2002

Identification in Drosophila melanogaster of the invertebrate G protein-coupled FMRFamide receptor.

We here describe the cloning and characterization of the functionally active Drosophila melanogaster (Drm) FMRFamide receptor, which we designated as DrmFMRFa-R. The full-length ORF of a D. melanogaster orphan receptor, CG 2114 (Berkeley Drosophila Genome Project), was cloned from genomic DNA. This receptor is distantly related to mammalian thyroid-stimulating hormone-releasing hormone receptors and to a set of Caenorhabditis elegans orphan receptors. An extract of 5,000 central nervous systems from the related but bigger flesh fly, Neobellieria bullata (Neb), was used to screen cells expressing the orphan receptor. Successive purification steps, followed by MS, revealed the sequence of two previously uncharacterized endogenous peptides, APPQPSDNFIRFamide (Neb-FIRFamide) and pQPSQDFMRFamide (Neb-FMRFamide). These are reminiscent of other insect FMRFamide peptides, having neurohormonal as well as neurotransmitter functions. Nanomolar concentrations of the Drm FMRFamides (DPKQDFMRFamide, TPAEDFMRFamide, SDNFMRFamide, SPKQDFMRFamide, and PDNFMRFamide) activated the cognate receptor in a dose-dependent manner. To our knowledge, the cloned DrmFMRFa-R is the first functionally active FMRFamide G protein-coupled receptor described in invertebrates to date.

Amino Acid Sequence↗
PubMed2025

The ecology, evolution, and physiology of Cardinium: a widespread heritable endosymbiont of invertebrates.

Candidatus Cardinium hertigii (Cardinium) are maternally transmitted obligate intracellular bacteria found in a wide range of invertebrate hosts, including arthropods and nematodes. Infection with Cardinium has substantial consequences for host biology, with many strains manipulating host reproduction to favor symbiont transmission by (i) feminizing male hosts, (ii) altering host sex allocation, (iii) inducing parthenogenesis, or (iv) causing cytoplasmic incompatibility. Other Cardinium strains can confer benefits to their host or alter host behavior. Cardinium-modified host phenotypes can result in selective sweeps of cytological elements through host populations and potentially reinforce host speciation. Cardinium has potential for applications in controlling arthropod pest species and arthropod-vectored disease transmission, although much remains to be explored regarding Cardinium physiology and host interactions. In this review, we provide an overview of Cardinium evolution and host distribution. We describe the various host phenotypes associated with Cardinium and how biological and environmental factors influence these symbioses. We also provide an overview of Cardinium metabolism, physiology, and potential mechanisms for interactions with hosts based on recent studies using genomics and transcriptomics. Finally, we discuss new methodologies and directions for Cardinium research, including improving our understanding of Cardinium physiology, response to environmental stress, and potential for controlling arthropod pest populations.

Symbiosis↗
PubMed1998

Cysteine-rich antimicrobial peptides in invertebrates.

Antimicrobial peptides are pivotal elements of the innate immune defense against bacterial and fungal infections. Within the impressive list of antimicrobial peptides available at present, more than half have been characterized in arthropods. Cysteine-rich antimicrobial peptides represent the most diverse and widely distributed family among arthropods and, to a larger extent, among invertebrates. Proeminent groups of cysteine-rich peptides are peptides with the CS alpha beta motif and peptides forming an hairpin-like beta-sheet structure. Although these substances exhibit a large structural diversity and a wide spectrum of activity, they have in common the ability to permeabilize microbial cytoplasmic membranes. Drosophila has proved a remarkable system for the analysis of the regulation of expression of gene encoding antimicrobial cysteine-rich peptides. These studies have unraveled the striking parallels that exist between insect immunity and innate immunity in mammals that point to a common ancestry of essential aspects of innate immunity.

Amino Acid Sequence↗
PubMedDate not supplied

Invertebrate cytokines: the phylogenetic emergence of interleukin-1.

Cytokines are polypeptides released by activated vertebrate blood cells which have profound effects on other blood cells and which have hormone-like properties affecting other organ systems as well. In recent years a wide variety of these mediators has been isolated and characterized. Many of these molecules have subsequently been cloned and expressed in E. coli. The tremendous importance of these proteins to host immune and non-specific defense systems along with the striking similarities of their properties among different species suggested to us that cytokines may have been proteins that have been conserved through evolution. Investigations of the evolution of cytokines will help us decipher the complex cellular, humoral and molecular interactions that regulate host defenses. Studies of the invertebrates will shed light on the phylogenetic emergence of these molecules as well.

Animals↗
PubMed2003

Polyspermy prevention in marine invertebrates.

In marine invertebrates, as in most other organisms, normal development requires that only one sperm nucleus joins with the egg nucleus at fertilization. The principal mechanisms employed are (1) prevention of sperm-egg plasma membrane fusion and (2) modifications of the egg extracellular coat to prevent sperm binding and/or penetration. In a third strategy, fertilization is polyspermic, but only one sperm nucleus fuses with the egg nucleus. Other factors such as gamete density during spawning, chemotaxis, and localized sites for sperm entry may also affect the numbers of sperm reaching the egg.

Animals↗
PubMed1990

Ultrastructure of sperm, spermiogenesis, and sperm-egg interactions in selected invertebrates and lower vertebrates which use external fertilization.

This review discusses the ultrastructure of sperm with reference to their development, the surface morphology of the egg, and the processes of sperm binding and penetration during fertilization. These topics are treated for selected invertebrates and lower vertebrates which live in aquatic environments and fertilize their eggs externally. Specifically, sperm eggs from cnidarians, echinoderms, decapod crustaceans, ascidians, lampreys, bony fishes, and amphibians are discussed. Sperm from the majority of these groups exhibit the classical head-midregion-tail configuration characteristic of primitive sperm. Specific variations within this general morphology have been described. The notable exceptions to the primitive-sperm paradigm are the sperm of decapod crustaceans and amphibians. Eggs from all of the animals considered are covered by complex vitelline envelopes except those of cnidarians. In general, the ultrastructural analysis of these egg envelopes shows that they are composed of fibrous subunits. Sperm bind to the vitelline envelope and then penetrate through it to fertilize the egg in all groups reviewed except fishes. In sperm ultrastructure which occur during penetration of the egg envelopes in both flagellated and non-flagellated sperm. These changes, which involve membrane fusion and reorganization as well as movement of membranous organelles, aid the sperm in reaching the actual site of gamete fusion.

Animals↗
PubMedDate not supplied

Discovering new invertebrate neuropeptides using mass spectrometry.

Neuropeptides are a complex set of messenger molecules controlling a wide array of regulatory functions and behaviors within an organism. These neuromodulators are cleaved from longer protein molecules and often experience numerous post-translational modifications to achieve their bioactive form. As a result of this complexity, sensitive and versatile analysis schemes are needed to characterize neuropeptides. Mass spectrometry (MS) through a variety of approaches has fueled the discovery of hundreds of neuropeptides in invertebrate species in the last decade. Particularly successful are direct tissue and single neuron analyses by matrix-assisted laser desorption/ionization (MALDI) MS, which has been used to elucidate approximately 440 neuropeptides, and examination of neuronal homogenates by electrospray ionization techniques (ESI), also leading to the characterization of over 450 peptides. Additional MS methods with great promise for the discovery of neuropeptides are MS imaging and large-scale peptidomics studies in combination with a sequenced genome.

Animals↗
PubMed1989

Neuronal plasticity in the adult invertebrate nervous system.

This essay provides a brief overview of neuronal plasticity in adult invertebrate nervous systems. Our discussion focuses on the factors which influence sprouting by adult neurons, i.e., (1) the nature of the neuron itself, (2) axon integrity, (3) the presence of targets, (4) diffusible factors, and (5) ageing. Evidence that the neurites of some adult neurons exhibit a dynamic equilibrium of expansion and retraction is presented, a topic which prompted us to speculate on the significance of such plasticity in altered behavioral states. We conclude with some suggestions as to specific questions that need to be addressed by future studies in this challenging area.

Animals↗