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At least 1,135 records · Page 63Linked to original sources
PubMed1994

Chronic haloperidol: neural correlates of motor disorders in an invertebrate model.

To analyse the mechanisms underlying chronic effects of antipsychotic drugs, a simpler invertebrate preparation is proposed. Bathing of leeches for three days in a 1.0 microM aqueous haloperidol (HAL) solution resulted in (i) discoordination of locomotion, including the inability of the posterior sucker to successfully attach to the substratum, and (ii) transmitter depletion in all putative dopamine (DA) neurones of the sucker and in some, but not all, DA neurones of middle body segments. Both behavioural restoration and cellular DA recovery were observed in disabled animals after bathing in 1.25 mM L-DOPA solution. We conclude that chronic HAL-produced motor disorders are causally related to DA deficiency.

Animals↗
PubMedDate not supplied

Blockade of mammalian and invertebrate calcium channels by lead.

We have compared the effects of Pb2+ on voltage-dependent calcium channels of the marine mollusc Aplysia, studied with a two electrode voltage clamp, with those on calcium channels in cultured rat dorsal root ganglion (DRG) neurons studied with whole cell patch clamp. In both preparations Pb2+ was a potent blocker of calcium channel currents at concentrations that did not significantly affect potassium and sodium currents. The blockade was concentration dependent and the percentage of blockade was reduced when the concentration of the charge carrier was elevated. In Aplysia the threshold Pb2+ concentration was about 1 microM, and the Hill coefficient near 1.0 under all conditions. Pb2+ did not significantly change inactivation but shifted the voltage dependence of activation to hyperpolarized voltages in a dose-dependent manner. The blockade of calcium currents by Pb2+ was highly voltage dependent and increased with depolarization. Rat dorsal root ganglion cells exhibit three different types of voltage-dependent calcium channels (N, L and T) which can be distinguished by the potential at which the channel activates or inactivates and by their sensitivity to pharmacologic antagonists. The IC50 for blockade of the L current was 1.03 microM with a Hill slope of 1.15. Currents elicited by voltage steps which activate N plus L currents had an IC50 of 0.64 microM and a Hill slope of 1.16. T currents were less sensitive, having an IC50 of 6 microM. Sodium and potassium currents were relatively unaffected in both preparations at concentrations at which the calcium channel was blocked more than 60% (1 microM or 200 microM respectively). The blockade in DRG neurons was less voltage-dependent and reversible than that in the invertebrate model system. These observations indicate that Pb2+ is a potent, reversible and selective blocker of voltage-dependent calcium channels at low concentrations.

Animals↗
PubMed1993

An invertebrate calcium-binding protein of the calbindin subfamily: protein structure, genomic organization, and expression pattern of the calbindin-32 gene of Drosophila.

Antisera against vertebrate calcium-binding proteins cross-react with Drosophila nervous and muscle tissue. We have used an antiserum against carp parvalbumin to isolate from a Drosophila head cDNA library immunopositive expression clones. Tissue in situ hybridization identified a clone that labeled specific neurons and muscles similar to the parvalbumin-like immunohistochemical staining pattern. Five independent cDNAs derive from an mRNA whose open reading frame codes for a 310 amino acid polypeptide. Sequence analysis identifies six EF-hand calcium-binding domains and reveals 42% and 37% homology to chicken calretinin and calbindin D-28k, respectively. Since the positions of 9 out of 10 introns within the ORF are conserved from the Drosophila gene to both vertebrate genes, we conclude that we have identified the first invertebrate member of the calbindin sub-family of calcium-binding protein genes of the EF-hand homolog family. The calbindin-32 gene (cbn) maps to 53E on the second chromosome. It is expressed through most of ontogenesis with a selective distribution in the nervous system and in a few small adult thoracic muscles. The cloning of a Drosophila homolog to vertebrate neuronal Ca(2+)-binding proteins opens new routes to study the so far largely elusive function of these brain molecules.

Amino Acid Sequence↗
PubMed1995

Blood-feeding arthropods: live syringes or invertebrate pharmacologists?

The habit of blood feeding evolved independently several times among the > 14,000 species and 400 genera of hematophagous arthropods. The specific need to remove blood from the host's skin led to sophisticated mechanical adaptations in invertebrate mouthparts. Moreover, the need to counteract the vertebrate host's hemostasis led to the evolution of salivary antihemostatic compounds injected into the host by these same mouthparts. The convergent evolution scenario for hematophagy has resulted in a large diversity of salivary anticlotting, antiplatelet, and vasodilatory substances. Thus, in addition to excelling as phlebotomists, hematophagous arthropods excel as pharmacologists.

Animals↗
PubMed1996

Invertebrate synapsins: a single gene codes for several isoforms in Drosophila.

Vertebrate synapsins constitute a family of synaptic proteins that participate in the regulation of neurotransmitter release. Information on the presence of synapsin homologs in invertebrates has been inconclusive. We have now cloned a Drosophila gene coding for at least two inferred proteins that both contain a region with 50% amino acid identity to the highly conserved vesicle- and actin-binding "C" domain of vertebrate synapsins. Within the C domain coding sequence, the positions of two introns have been conserved exactly from fly to human. The positions of three additional introns within this domain are similar. The Drosophila synapsin gene (Syn) is widely expressed in the nervous system of the fly. The gene products are detected in all or nearly all conventional synaptic terminals. A single amber (UAG) stop codon terminates the open reading frame (ORF1) of the most abundant transcript of the Syn gene 140 amino acid codons downstream of the homology domain. Unexpectedly, the stop codon is followed by another 443 in-frame amino acid codons (ORF2). Using different antibodies directed against ORF1 or ORF2, we demonstrate that in the adult fly small and large synapsin isoforms are generated. The small isoforms are only recognized by antibodies against ORF1; the large isoforms bind both kinds of antibodies. We suggest that the large synapsin isoform in Drosophila may be generated by UAG read-through. Implications of such an unconventional mechanism for the generation of protein diversity from a single gene are discussed.

Amino Acid Sequence↗
PubMed1996

Morphine-induced conformational changes in human monocytes, granulocytes, and endothelial cells and in invertebrate immunocytes and microglia are mediated by nitric oxide.

We evaluated the contribution of nitric oxide (NO) to morphine-induced rounding of spontaneously activated (mobile) ameboid human monocytes, granulocytes, or arterial endothelial cells and invertebrate immunocytes and microglia. Morphine induced significant rounding and inactivation of ameboid cells within 20 min except for arterial endothelial cells, which became rounded 24 h after morphine exposure. The effects of morphine on cell conformation were blocked in the presence of N-nitro-L-arginine, a nitric oxide synthase inhibitor. Treatment of cells with the NO donor, sodium nitroprusside, induced cell rounding similar to that observed following morphine exposure, suggesting that NO release may mediate morphine-induced changes in cell conformation. The contribution of NO release to morphine-induced cell rounding was determined by direct evaluation of NO concentration in real-time using a NO-specific amperometric probe. Significant increases in NO concentration were observed 2 min after morphine stimulation, whereas morphine-induced NO release was markedly impaired by pretreatment with N-nitro-L-arginine or the opiate alkaloid antagonist, naloxone. In contrast, opioid peptides failed to induce NO release, consistent with our previous observations that demonstrated the failure of opioid peptides to promote cell rounding. Taken together, these data suggest that morphine-induced NO release may be mediated by activation of the opiate alkaloid-selective, opioid peptide-insensitive micro3 receptor, and that functional coupling of morphine to NO production has been conserved during evolution and may modulate cellular activation.

Animals↗
PubMed1995

Cytokines and invertebrate immune responses.

A profound interrelationship between cytokines and invertebrate (molluscs) immune responses has been reported. Different cytokines (IL-1 alpha, IL-2 and TNF-alpha) significantly stimulate molluscan hemocyte motility, increasing phagocytic activity and provoking the induction of nitric oxide synthase. As far as cell motility is concerned, the response to different cytokines varied between species. These and other recently reported findings (Ottaviani et al (1994) FEBS Lett 351, 19-21; Ottaviani et al (1995) Biochem Biophys Res Commun 207, 288-292) suggest that cytokines are important, ancestral, and functionally conserved molecules, which have also maintained their pleiotropicity, redundancy in the mode of action, and high promiscuity of their receptors during evolution.

Animals↗
PubMed1996

Labelling of breast carcinoma, thyroid carcinoma and melanoma with manno- and galacto-specific lectins from marine invertebrates.

Three marine invertebrate FITC-labelled lectins, CNL, GCL, and GSL, isolated respectively, from the sponges Chondrilla nucula, Geodia cydonium, and the hexacoral Gerardia savaglia, were used as potential diagnostic tools for different breast tumors. The lectins vary in their carbohydrate binding properties: GSL is D-mannose specific, GCL and CNL D-galactose specific. GSL labels most investigated types of malignant tissues distinctively, while the results with CNL and GCL are less consistent. The well known D-mannose specific lectin, concanavalin A, also binds to tumor tissues, but with much lower intensity than GSL.

Animals↗
PubMedDate not supplied

Importance of tropomyosin in the allergy to household arthropods. Cross-reactivity with other invertebrate extracts.

The aim of the study was to investigate the involvement of the actin binding protein tropomyosin in the allergic sensitization of patients to household arthropods, as well as to study its panallergenic character in relation to other invertebrate extracts. Three arthropod extracts were prepared, namely fly (Musca domestica), moth (Ephestia spp.) and spider (Tegenaria spp.), and used to evaluate by cutaneous and RAST tests a population of 100 household arthropod allergic patients. Twenty-nine sera were selected for the subsequent SDS-PAGE Immunoblotting assays. IgE binding bands at 36, 34, 31, 27 and 17 kDa were detected in the fly extract by more than 50% of tested sera. In moth and spider extracts, the more relevant allergens were found at 34, 31, 24 and 110, 38, 35, 26, 19 kDa, respectively. A commercial polyclonal antiserum anti-chicken muscle tropomyosin was used for tropomyosin identification. Cross-reactivity studies performed by SDS-PAGE Immunoblotting, using a pool of household arthropod allergic patients and tropomyosin antiserum, preliminarily demonstrated the presence of such protein as a cross-reacting allergen in a large variety of extracts obtained from insects, mites, crustaceans, mollusks and parasites.

Allergens↗
PubMed1997

[Antineoplastic glycoproteins in marine invertebrates].

We searched marine invertebrates for new host defence molecules. We found several new cytolytic factors in Arthropoda and Mollusca. Especially, sea hares were revealed to have strong antitumor glycoproteins. These novel glycoproteins were purified to apparent homogeneity from Aplysia kurodai and Dolabella auricularia, and designated aplysianins and dolabellanins, respectively. The isolated glycoproteins lysed all the tumor cells tested, including TNF-resistant cells, but did not lyse normal white and red blood cells. The glycoproteins completely inhibited the synthesis of DNA and RNA by tumor cells within 2 hours and caused tumor lysis within 18 hours. Cytolysis was inhibited by the presence of N-acetylneuraminic acid, suggesting that the recognition of the sugar moiety is a key step in the tumor lysis by these antineoplastic glycoproteins from sea hares. These antitumor factors, except dolabellanins C and P, also showed anti-microbial activities. The sequence of the N-terminal part of dolabellanin A was similar to aplysianin A and achacin.

Animals↗
PubMedDate not supplied

Evolution of cooperativity in hemoglobins: what can invertebrate hemoglobins tell us?

While vertebrate hemoglobins typically are tetrameric and show highly regulated and cooperative ligand binding, little is known of the evolution of these properties. We are studying the structural and functional properties of the hemoglobins from Caudina arenicola, an echinoderm. The echinoderms are in the lineage most closely related to the vertebrates to express hemoglobin. C. arenicola has three sets of red cells, in the water vascular system, the coelomic cavity, and in an intestinal vein. Each of these expresses a distinct array of globins. The hemoglobins are cooperative and exhibit unusual ligand-linked associative properties, being dimeric when oxygenated and forming tetramers and higher aggregates on deoxygenation. The major coelomic hemoglobins have been subjected to a detailed examination by a combination of ligand binding analyses and protein and DNA sequencing, as well as X-ray crystallography. Two typical globin introns were identified, along with a unique intron that bisects an N-terminal extension of the globin from the remainder of the gene. X-ray crystallographic analysis shows that the subunit interfaces of C. arenicola hemoglobins differ radically from those of vertebrate hemoglobins and indeed from some other invertebrate hemoglobins, but closely resemble the packing arrangements found in a clam hemoglobin (Scapharca). However, the residues implicated in cooperativity in these two types of hemoglobins differ substantially.

Animals↗
PubMed1998

Antifouling activity of Indian marine invertebrates against the green mussel Perna viridis L.

Thirty-one species of marine invertebrates collected from the Indian Coast, belonging to six phyla (Porifera, Coelenterata, Annelida, Mollusca, Echinodermata, and Eurochordata) were tested for antifouling activity against the green mussel Perna viridis L. The repulsive action of the foot and production of byssus threads by green mussels were used for assaying the above activity. Subergorgia suberosa, Sinularia numerosa, Sinularia compressa, Cladiella pachyclados (phylum Coelenterata), Haliclona sp. (phylum Porifera), and Planaxis sulcatus (phylum Mollusca) have shown to be potential sources of antifoulants.

Journal Article↗