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At least 577 records · Page 32Linked to original sources
PubMed2006

An invertebrate TNF functional analogue activates macrophages via lectin-saccharide interaction with ion channels.

The invertebrate pattern-recognition protein named coelomic cytolytic factor (CCF) and the mammalian cytokine tumor necrosis factor (TNF) share functional analogies that are based on a similar saccharide recognition specificity. In particular, CCF and TNF have been shown to interact with ion channels on the surface of vertebrate cells via N,N'-diacetylchitobiose lectin-like activity. In the present study, we show that CCF-induced membrane depolarization results in the release of TNF, IL-6 and nitric oxide (NO) by macrophages via nuclear factor-kappaB signaling. Interestingly, our data suggest that TNF contributes, through lectin-saccharide interaction, to the secretion of IL-6 and NO induced by CCF. This experimental non-physiological setting based on the interaction of an invertebrate defense lectin with vertebrate cells involved in the innate immune response may have highlighted an evolutionarily ancient mechanism of macrophage activation in vertebrates.

Animals↗
PubMed1989

Comparative monolayer investigations of surface properties of negatively charged glycosphingolipids from vertebrates (gangliosides) and invertebrates (SGL-II, lipid IV).

The surface properties of four negatively charged glycosphingolipids from vertebrates, the sialo-glycosphingolipids (= gangliosides) GM1, GD1a, GT1b and a sulfo-glycosphingolipid (= sulfatide), and of the two negatively charged glycosphingolipids from lower invertebrates, the glucurono-glycosphingolipid Lipid IV and the aminophosphono-glycosphingolipid SGL-II were investigated in monolayers at the air/water interface. The molecular peculiarities under investigation were surface pressure (pi) and surface potential (delta V) which are described for Lipid IV and SGL-II for the first time. The surface pressure/area isotherms of all glycosphingolipids were typical of a liquid-expanded monolayer and, with the exception of SGL-II, exhibited a phase transition to a liquid-condensed state at surface pressures above 20 mN/m. The surface potential/molecular area data found for gangliosides in the closely packed state at pi = 30 mN/m (GM1: delta V = -17 mV; GD1a: delta V = -35 mV; GT1b: delta V = -39 mV) showed only a slight influence of the additional number of negatively charged residues. For Lipid IV, the surface behavior was very similar to GM1 both possessing one negative group per molecule, whereas in SGL-II also the surface potential data (delta V = +173 mV) were different compared with GD1a both possessing two negative groups per molecule. The addition of Ca2+ condensed the monolayers of all glycolipids and increased the potential in the direction to more positive values, but these findings were less effective in SGL-II films. On the basis of monolayer results presented here, in biological membranes of invertebrates especially Lipid IV might play a similar role as the ganglioside GM1 in vertebrate cells.

Acidic Glycosphingolipids↗
PubMed2000

Water-borne sperm trigger vitellogenic egg growth in two sessile marine invertebrates.

A diverse array of sessile marine invertebrates mate by passive dispersal of sperm which fertilize the brooded eggs of neighbours. In two such species, a sea-mat (phylum Bryozoa) and an ascidian (phylum Chordata), vitellogenic egg growth is absent in reproductively isolated specimens, but is triggered by a water-borne factor released by conspecifics. In both of these colonial, hermaphroditic species, the active factor can be removed from water by filtration. The effect involves self-/non-self-recognition: water conditioned by a separate subcolony of the same genetic individual does not prompt oocyte growth. In each species, allosperm move from the surrounding water to the ovary and are then stored in close association with the growing oocytes. We concluded that sperm themselves are the water-borne factor that triggers the major phase of female reproductive investment. This mechanism is, to our knowledge, previously undescribed in animals, but has parallels with the initiation of maternal investment in flowering plants following the receipt of compatible pollen. The species studied may be representative of many other aquatic invertebrates which mate in a similar way. The stimulation of egg growth by allosperm could lead to intersexual conflict during oogenesis.

Animals↗
PubMed2005

Effects on weed and invertebrate abundance and diversity of herbicide management in genetically modified herbicide-tolerant winter-sown oilseed rape.

We evaluated the effects of the herbicide management associated with genetically modified herbicide-tolerant (GMHT) winter oilseed rape (WOSR) on weed and invertebrate abundance and diversity by testing the null hypotheses that there is no difference between the effects of herbicide management of GMHT WOSR and that of comparable conventional varieties. For total weeds, there were few treatment differences between GMHT and conventional cropping, but large and opposite treatment effects were observed for dicots and monocots. In the GMHT treatment, there were fewer dicots and monocots than in conventional crops. At harvest, dicot biomass and seed rain in the GMHT treatment were one-third of that in the conventional, while monocot biomass was threefold greater and monocot seed rain almost fivefold greater in the GMHT treatment than in the conventional. These differential effects persisted into the following two years of the rotation. Bees and Butterflies that forage and select for dicot weeds were less abundant in GMHT WORS management in July. Year totals for Collembola were greater under GMHT management. There were few other treatment effects on invertebrates, despite the marked effects of herbicide management on the weeds.

Agriculture↗
PubMed2002

Pseudoalteromonas ruthenica sp. nov., isolated from marine invertebrates.

On the basis of phenotypic and genotypic characteristics and analysis of 165 rRNA sequences, a novel species belonging to the genus Pseudoalteromonas is described. Two pale-orange-pigmented strains, KMM 300T and KMM 290, isolated respectively from a mussel, Crenomytilus grayanus, and a scallop, Patinopecten yessoensis, are marine, gram-negative, aerobic, rod-shaped bacteria that produce a number of antimicrobial compounds. The strains are able to degrade gelatin, elastin, starch, DNA and Tween 80. Chitin and agar are not degraded. The isolates from marine invertebrates grew at NaCl concentrations of 1-9% and a temperature range of 10-35 degrees C and did not utilize most of the wide range of carbohydrates tested, with the exception of D-glucose, cellobiose and sucrose. The DNA G+C content was 48.4-48.9 mol%. The level of DNA homology of the two strains was 98%. DNA from the strains isolated from marine invertebrates showed 5-15% genetic relatedness to the DNA of other type strains of the genus Pseudoalteromonas. 16S rRNA analysis indicated a clear affiliation of the novel bacteria to other species of the genus. The strains are assigned to a novel species, Pseudomonas ruthenica sp. nov., with the type strain KMM 300T (= LMG 19699T = CIP 106857T).

Animals↗
PubMed2002

Phylogenetic analysis identifies the invertebrate pathogen Helicosporidium sp. as a green alga (Chlorophyta).

Historically, the invertebrate pathogens of the genus Helicosporidium were considered to be either protozoa or fungi, but the taxonomic position of this group has not been considered since 1931. Recently, a Helicosporidium sp., isolated from the blackfly Simulium jonesi Stone & Snoddy (Diptera: Simuliidae), has been amplified in the heterologous host Helicoverpa zea. Genomic DNA has been extracted from gradient-purified cysts. The 185, 28S and 5.8S regions of the Helicosporidium rDNA, as well as partial sequences of the actin and beta-tubulin genes, were amplified by PCR and sequenced. Comparative analysis of these nucleotide sequences was performed using neighbour-joining and maximum-parsimony methods. All inferred phylogenetic trees placed Helicosporidium sp. among the green algae (Chlorophyta), and this association was supported by bootstrap and parsimony jackknife values. Phylogenetic analysis focused on the green algae depicted Helicosporidium sp. as a close relative of Prototheca wickerhamii and Prototheca zopfii (Chlorophyta, Trebouxiophyceae), two achlorophylous, pathogenic green algae. On the basis of this phylogenetic analysis, Helicosporidium sp. is clearly neither a protist nor a fungus, but appears to be the first described algal invertebrate pathogen. These conclusions lead us to propose the transfer of the genus Helicosporidium to Chlorophyta, Trebouxiophyceae.

Actins↗
PubMed1990

Pharmacological evidence for the modulation of monoamine release by adenosine in the invertebrate nervous system.

An in vitro preparation from the pedal ganglia of the marine bivalve, Mytilus edulis, was used to examine the modulation of transmitter release by adenosine and its analogs from invertebrate nervous tissue. The ganglia of this organism contain the monoamines dopamine (DA), serotonin (5-HT), and norepinephrine (NE), and the presynaptic release of these substances is known to be calcium-dependent. This organism also contains a DA-sensitive adenylate cyclase system which resembles that seen in mammals. Neural tissue from the pedal ganglia was incubated with labeled monoamines, and release studies were then conducted in superfusion chambers; release of monoamines was evoked by the addition of 50 mM KCl. Addition to the superfusion medium of the adenosine analog, 5'-N-ethylcarboxamidoadenosine (NECA; 10 nM), inhibited the release of 5-HT and DA, and to a lesser extent NE, whereas 100-fold higher concentrations of adenosine itself and the adenosine analog, R-N6-phenylisopropyladenosine, were required to achieve comparable levels of inhibition. The inhibitory effects of NECA on neurotransmitter release were blocked by the adenosine receptor antagonist, theophylline (IC50 = 10-14 microM). The results from this study indicate for the first time the possible role of adenosine as a modulator of neurotransmitter release in the invertebrate nervous system.

Adenosine↗
PubMed1981

Elastic arteries in invertebrates: mechanics of the octopus aorta.

The aorta of the octopus, Octopus dofleini, is a highly distensible, elastic tube. The circumferential elastic modulus increases with inflation in the physiological range from abut 10(4) to 10(5) newtons per square meter. Rubber-like fibers have been isolated, apparently for the first time, from the aorta of an invertebrate. These fibers have an elastic modulus, like elastin, of about 4 x 10(5) newtons per square meter and are present in sufficient quantity to account for the elastic properties of the intact vessel under physiological conditions. Thus the circulatory system of an invertebrate animal provides an "elastic reservoir" (much like that of the vertebrate system), which increases the efficiency of the circulation.

Animals↗
PubMed2004

Induction of antiviral immunity by double-stranded RNA in a marine invertebrate.

Vertebrates mount a strong innate immune response against viruses, largely by activating the interferon system. Double-stranded RNA (dsRNA), a common intermediate formed during the life cycle of many viruses, is a potent trigger of this response. In contrast, no general inducible antiviral defense mechanism has been reported in any invertebrate. Here we show that dsRNA induces antiviral protection in the marine crustacean Litopenaeus vannamei. When treated with dsRNA, shrimp showed increased resistance to infection by two unrelated viruses, white spot syndrome virus and Taura syndrome virus. Induction of this antiviral state is independent of the sequence of the dsRNA used and therefore distinct from the sequence-specific dsRNA-mediated genetic interference phenomenon. This demonstrates for the first time that an invertebrate immune system, like its vertebrate counterparts, can recognize dsRNA as a virus-associated molecular pattern, resulting in the activation of an innate antiviral response.

Animals↗
PubMed1996

Surfeit locus gene homologs are widely distributed in invertebrate genomes.

The mouse Surfeit locus contains six sequence-unrelated genes (Surf-1 to -6) arranged in the tightest gene cluster so far described for mammals. The organization and juxtaposition of five of the Surfeit genes (Surf-1 to -5) are conserved between mammals and birds, and this may reflect a functional or regulatory requirement for the gene clustering. We have undertaken an evolutionary study to determine whether the Surfeit genes are conserved and clustered in invertebrate genomes. Drosophila melanogaster and Caenorhabditis elegans homologs of the mouse Surf-4 gene, which encodes an integral membrane protein associated with the endoplasmic reticulum, have been isolated. The amino acid sequences of the Drosophila and C. elegans homologs are highly conserved in comparison with the mouse Surf-4 protein. In particular, a dilysine motif implicated in endoplasmic reticulum localization of the mouse protein is conserved in the invertebrate homologs. We show that the Drosophila Surf-4 gene, which is transcribed from a TATA-less promoter, is not closely associated with other Drosophila Surfeit gene homologs but rather is located upstream from sequences encoding a homolog of a yeast seryl-tRNA synthetase protein. There are at least two closely linked Surf-3/rpL7a genes or highly polymorphic alleles of a single Surf-3/rpL7a gene in the C. elegans genome. The chromosomal locations of the C. elegans Surf-1, Surf-3/rpL7a, and Surf-4 genes have been determined. In D. melanogaster the Surf-3/rpL7a, Surf-4, and Surf-5 gene homologs and in C. elegans the Surf-1, Surf-3/rpL7a, Surf-4, and Surf-5 gene homologs are located on completely different chromosomes, suggesting that any requirement for the tight clustering of the genes in the Surfeit locus is restricted to vertebrate lineages.

Amino Acid Sequence↗
PubMed1985

Role of the marginal band in an invertebrate erythrocyte: evidence for a universal mechanical function.

Marginal bands of microtubules are present in erythrocytes of all nonmammalian vertebrates and some invertebrates, in which they are thought to play a role in erythrocyte morphogenesis. Recently, marginal bands have also been implicated in maintenance of shape in vertebrate erythrocytes and platelets subjected to external mechanical forces. Here we demonstrate that marginal bands in an invertebrate ("blood clam") erythrocyte act similarly. Cells with and without marginal bands at the same temperature were prepared by (a) nocodazole or colchicine inhibition of marginal band reassembly following 0 degree C disassembly, (b) taxol inhibition of marginal band disassembly at 0 degree C, and (c) taxol induction of marginal band reassembly at 0 degree C. As shown previously for temperature-induced marginal band reassembly in this species, taxol-induced reassembly at 0 degree C occurred in association with centrioles. When erythrocytes with and without marginal bands were compared for their response to the mechanical stress of fluxing through capillary tubes, many more of those without marginal bands tended to become folded or buckled regardless of the method used to prepare them. The results provide evidence that marginal bands have a universal mechanical function in mature erythrocytes.

Alkaloids↗
PubMed1977

Invertebrate gap junctions.

Both glycerol and glutaraldehyde, the two most commonly used chemical aids in freeze-fractue studies, have been shown individually to affect the structure of certain membranes as observed in freeze-fracture replicas. The present investigation studied the effect of glycerol on the gap junctions found in a number of tissues from several invertebrate phyla. Glycerol was shown, in some of these tissues, to affect both the spatial arrangement of the particles within the membrane and their fracturing properties if the tissue had not been prefixed with glutaraldehyde. It is suggested that the effect of glycerol on invertebrate gap junctions may be of diagnostic use in enabling them to be separated into a number, or spectrum, of types. Previously B-type gap junctions have been reported only in Arthropoda. This study has extended knowledge of their occurrence into the phyla Coelenterata, Platyhelminthes and Annelida. The B-type gap junctions appear consistently to have a 12-nm particle separation, which is larger than the 10-nm separation found in vertebrate and molluscan A-type gap junctions.

Animals↗
PubMed2004

Anatomy of a live invertebrate revealed by manganese-enhanced Magnetic Resonance Imaging.

Non-invasive imaging technologies such as Magnetic Resonance Imaging (MRI) are increasingly in demand by researchers in many biological disciplines. However, when imaging small animals such as invertebrates, not only is the use of high-field magnets necessary to gain satisfactory spatial resolution, but the achievement of adequate contrast between tissues also requires the identification of applicable imaging parameters by means of expensive and time-consuming procedures. Here we report that systemically administered manganese can act as an effective MRI contrast agent for quick and non-invasive imaging of the nervous system and other complex anatomical structures in a small aquatic animal. Due to the tendency of manganese ions to differentially accumulate in most soft tissues, higher overall signal intensity and strongly improved contrast between structures yield data well suited for digital post-processing into three-dimensional models. Within a few hours this technique can efficiently generate anatomical images that are not obtainable with conventional methods, thus demonstrating a new and exciting approach to invertebrate research.

Animals↗
PubMed2005

Mitochondrial depolarization following hydrogen sulfide exposure in erythrocytes from a sulfide-tolerant marine invertebrate.

Sulfide-tolerant marine invertebrates employ a variety of mechanisms to detoxify sulfide once it has entered their bodies, but their integumentary, respiratory epithelium and circulatory cells may still be exposed to toxic sulfide concentrations. To investigate whether sulfide exposure is toxic to mitochondria of a sulfide-tolerant invertebrate, we used the fluorescent dyes JC-1 and TMRM to determine the effect of sulfide exposure on mitochondrial depolarization in erythrocytes from the annelid Glycera dibranchiata. In erythrocytes exposed to 0.11-1.9 mmol l-1 sulfide for 1 h, the dyes showed fluorescence changes consistent with sulfide-induced mitochondrial depolarization. At the highest sulfide concentration, the extent of depolarization was equivalent to that caused by the mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP). Even when induced by as little as 0.3 mmol l-1 sulfide, the depolarization was not reversible over a subsequent 5 h recovery period. The mechanism of toxicity was likely not via inhibition of cytochrome c oxidase (COX), since other COX inhibitors and other mitochondrial electron transport chain inhibitors did not produce similar effects. Furthermore, pharmacological inhibition of the mitochondrial permeability transition pore failed to prevent sulfide-induced depolarization. Finally, increased oxidation of the free radical indicators H2DCFDA and MitoSOX in erythrocytes exposed to sulfide suggests that sulfide oxidation increased oxidative stress and superoxide production, respectively. Together, these results indicate that sulfide exposure causes mitochondrial depolarization in cells of a sulfide-tolerant annelid, and that this effect, which differs from the actions of other COX inhibitors, may be via increased free radical damage.

Analysis of Variance↗
PubMed1994

IMMUNOLOCALIZATION OF AN ANTIGEN ASSOCIATED WITH THE INVERTEBRATE ELECTROGENIC 2Na+/1H+ ANTIPORTER

Epithelial plasma membranes from crustacean gut, kidney and gills have been shown recently to display an electrogenic 2Na+/1H+ antiporter that differs considerably in its physiological properties from the vertebrate electroneutral 1Na+/1H+ exchange paradigm. In this study, we describe the histological and cytological localization of an antigen associated with invertebrate electrogenic 2Na+/1H+ antiport in lobster (Homarus americanus) tissues using a monoclonal antibody (MAb 11) raised in mice against purified brush border membranes of the hepatopancreatic epithelium. Previous work showed that MAb 11 inhibited electrogenic 2Na+/1H+ and Ca2+/H+ exchange by hepatopancreatic brush border membrane vesicles, but was without effect on Na+-dependent d-glucose transport, suggesting a restricted inhibitory specificity to the cation exchanger. MAb 11 binding occurred at hepatopancreatic epithelial R-cell brush border membranes, at plasma membranes of the antennal gland and gill podocytes, and at vacuolar membranes of hepatopancreatic B- and R-cells, gill nephrocytes and epithelial cells of the antennal gland labyrinth and gill lamellae, as assessed by FITC-labelled secondary antibodies. Control FITC-labelled antibodies raised in mice against vertebrate keratin proteins displayed only weak non-specific binding to the tissues and cells responding intensely to MAb 11, supporting the specific nature of MAb 11 binding to its cognate antigen. The broad histological and cytological distribution of MAb 11 binding to plasma membranes and vacuolar membranes from several lobster organ systems suggests that the physiological activities regulated by its antigen, possibly an element of the invertebrate electrogenic cation exchanger, may be diverse.

Journal Article↗
PubMed1995

Coulometric measurement of oxygen consumption during development of marine invertebrate embryos and larvae

Determining the metabolic rate of larval invertebrates from aquatic habitats is complicated by the problems of small size and the scarcity of suitable measurement techniques. In this study, coulometric respirometry (a new technique for the study of marine embryos and larvae) was used to explore several issues associated with the rate of energy use during embryonic and larval development of marine invertebrates from three phyla. Coulometric respirometry measures rates of oxygen consumption under normoxic conditions by electrochemically replacing the oxygen consumed by organisms during an experiment. This technique is based on the assumption that all electrons consumed by the anodic reactions result in the production of oxygen. We verify this assumption using direct measurements of oxygen production and show that the technique is sensitive enough (1 nmol O2 h-1) to quantify the oxygen consumption of a single individual swimming freely in a relatively large volume (2 ml). Continuous measurements can span days, and embryos in the coulometric respiration chambers develop to the larval stage at normal rates of differentiation. Measurements of metabolic rates were made with the coulometric respirometer during the complete life-span of larvae of three species (asteroid, Asterina miniata; bivalve, Crassostrea gigas; echinoid, Dendraster excentricus). For these species, metabolic power equations had mass exponents near unity (0.9­1.1), showing that metabolic rate scales isometrically with mass during larval growth. Metabolic rates were independent of the concentration of larvae used in the respirometer chambers for a range of larval concentrations from 4 to 400 larvae ml-1 (coulometric respirometer) and from 241 to 809 larvae ml-1 (polarographic oxygen sensor). Metabolic rates were measured using coulometric respirometry and two other commonly used techniques, polarographic oxygen sensors and Winkler's titration. Polarographic oxygen sensors in small, sealed chambers (100 µl) consistently gave the lowest values (by as much as 80 %) for the asteroid, echinoid and molluscan larvae. By comparison, rates of oxygen consumption measured using coulometric respirometry and Winkler's titration (to measure the change in oxygen concentration over time) were similar and consistently higher. Although the polarographic oxygen sensor is the most widely used method for measuring the metabolism of small animals in sealed 100­1000 µl chambers, it appears that the metabolism of some larvae is adversely affected by the conditions within these respirometers.

Journal Article↗
PubMed2001

Inositol-1,4,5-trisphosphate-binding proteins controlling the phototransduction cascade of invertebrate visual cells.

The main phototransduction cascade in invertebrate visual cells involves the turnover of phosphatidylinositol, an important biochemical mechanism common to many signal-transduction systems. Light-activated rhodopsin stimulates guanine nucleotide exchange on the Gq class of G-protein, which activates phospholipase C to hydrolyze phosphatidylinositol 4,5-bisphosphate to inositol-1,4,5-trisphosphate and diacylglycerol. Subsequently, inositol-1,4,5-trisphosphate-binding proteins continue the signal cascade. Here, we report on the first inositol-1,4,5-trisphosphate-binding proteins demonstrated in an invertebrate visual system with our investigation of the photosensitive rhabdoms of squid. We screened the ability of proteins to interact with inositol-1,4,5-trisphosphate by affinity column chromatography with an inositol-1,4,5-trisphosphate analogue. We detected an inositol-1,4,5-trisphosphate-binding affinity in phospholipase C, receptor kinase and five other proteins in the cytosolic fraction and, surprisingly, rhodopsin in the membrane fraction. A binding assay with (3)H-labelled inositol-1,4,5-trisphosphate demonstrated the inositol-1,4,5-trisphosphate affinity of each of the purified proteins. Since rhodopsin, receptor kinase and phospholipase C are involved upstream of phosphatidylinositol turnover in the signal cascade, our result suggests that phosphatidylinositol turnover is important in feedback pathways in the signalling system.

Animals↗
PubMed2001

An invertebrate model of the developmental neurotoxicity of insecticides: effects of chlorpyrifos and dieldrin in sea urchin embryos and larvae.

Chlorpyrifos targets mammalian brain development through a combination of effects directed at cholinergic receptors and intracellular signaling cascades that are involved in cell differentiation. We used sea urchin embryos as an invertebrate model system to explore the cellular mechanisms underlying the actions of chlorpyrifos and to delineate the critical period of developmental vulnerability. Sea urchin embryos and larvae were exposed to chlorpyrifos at different stages of development ranging from early cell cleavages through the prism stage. Although early cleavages were unaffected even at high chlorpyrifos concentrations, micromolar concentrations added at the mid-blastula stage evoked a prominent change in cell phenotype and overall larval structure, with appearance of pigmented cells followed by their accumulation in an extralarval cap that was extruded from the animal pole. At higher concentrations (20-40 microM), these abnormal cells constituted over 90% of the total cell number. Studies with cholinergic receptor blocking agents and protein kinase C inhibitors indicated two distinct types of effects, one mediated through stimulation of nicotinic cholinergic receptors and the other targeting intracellular signaling. The effects of chlorpyrifos were not mimicked by chlorpyrifos oxon, the active metabolite that inhibits cholinesterase, nor by nonorganophosphate cholinesterase inhibitors. Dieldrin, an organochlorine that targets GABA(A )receptors, was similarly ineffective. The effects of chlorpyrifos and its underlying cholinergic and signaling-related mechanisms parallel prior findings in mammalian embryonic central nervous system. Invertebrate test systems may thus provide both a screening procedure for potential neuroteratogenesis by organophosphate-related compounds, as well as a system with which to uncover novel mechanisms underlying developmental vulnerability.

Animals↗