SEARCH · Search PubMed

Results for “Teleost”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources

PubMed1996

Lithium transport in the chicken and marine teleost kidney.

The clearance ratio-C(Li)/C(ln) (Excretion Fraction of Lithium-EFLi) in the cod (Gadus morrhua L.) kidney amounts to 15.1 +/- 4.7, in the black sculpin (Myoxocephalus scorpius L.) kidney, to 6.88 +/- 1.22, which indicates secretion of lithium by the marine teleost kidney. A direct correlation has been found between EFLi and EFMg. Injection of furosemide (15 mg/kg B.W.) increase while injection of the 20% para-amino-hippurate solution (1.6 ml/kg B.W.) does not change EFLi in the cod kidney. Infusion of 10 mM LiNO3 in the 0.9% NaCl solution (3.5 ml/kg B.W.) into the chicken (Gallus domesticus L.) left v. saphena produces, owing to the lithium inflow into the renoportal system, a marked unilateral increase of the renal lithium excretion. Infusion of 10% NaCl solution (3.5 ml/kg B.W.) together with 10 mM LiNO3 into the chicken left v. saphena is accompanied by a more pronounced ipsilateral increase of the lithium excretion and EFLi. The data obtained indicate diversity of mechanisms (glomerular filtration, reabsorption and secretion) participating in the renal lithium excretion in the animals studied.

Animals↗

PubMed1992

Involvement of cyclic adenosine monophosphate in the stimulation of gonadotropin secretion from the pituitary of the teleost fish, tilapia.

The present study examines the involvement of cAMP in the transduction of the short-term effect of gonadotropin-releasing hormone (GnRH) on gonadotropin release in the teleost fish, tilapia. A 5 min pulse of dibutyryl cyclic AMP (dbcAMP; 0.03-3 mM) or forskolin (0.1-10 microM) resulted in dose-dependent surges in tilapia gonadotropin (taGTH) secretion from the perifused pituitary. The initial increase in taGTH in response to dbcAMP (3 mM) occurred within 6 min. The concentration of cAMP in the effluent medium increased about 20-fold after a pulse of [D-Ala6,Pro9-NEt]-luteinizing hormone-releasing hormone (LHRH) (GnRHa; 100 nM). To rule out the possibility that the observed effects were due to stimulation by endogenous GnRH release from intact nerve terminals present in the fragments, further experiments were performed in primary cultures of dispersed pituitary cells. Exposure (30 min) of the cells to forskolin (0.01-1.0 microM) resulted in a dose-dependent increase in taGTH release similar to that achieved by GnRHa (1 pM to 10 nM). Also 8-bromo cAMP (0.01-1.0 mM) evoked a dose-related increase in taGTH release. A 3-fold increase in the release occurred in the presence of isobutylmethylxanthine (IBMX) (0.2 mM), similar to that obtained by GnRHa (1.0 nM) in the absence of IBMX. However, when combined, the increase in taGTH release was 16-fold. Moreover, exposure of the cultured cells to GnRHa (0.1 or 10 nM, 60 min) resulted in a dose-related elevation of intracellular cAMP levels and taGTH release.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗

PubMed1995

Possible sites of dopaminergic inhibition of gonadotropin release from the pituitary of a teleost fish, tilapia.

The present study is an attempt to find sites of dopaminergic inhibition along the transduction cascades culminating in gonadotropin (GtH) release in a teleost fish, tilapia. Experiments were carried out on perifused pituitary fragments and in primary culture of trypsinized pituitary cells. Salmon GnRH, chicken GnRH I and II stimulated GtH release in culture with estimated ED50 values of 15.56 pM, 2.55 nM and 8.65 pM, respectively. Apomorphine (APO; 1 microM) totally abolished this stimulation. Dopamine (DA; 1 microM) reduced both basal and GnRHa-stimulated GtH release from perifused pituitary fragments but did not alter the formation of cAMP. In a similar perifusion experiment DA abolished GtH release in response to forskolin (10 microM) with no reduction in cAMP formation. This indicates that one site of the dopaminergic inhibition is distal to cAMP formation, an indication not compatible with the classic characteristic of DA D2 type mode of action. The inhibition of GtH release in culture, caused by 1 microM APO, the specific DA D2 agonists LY 171555 (LY) or bromocryptine (BRCR) could not be reversed by activating protein kinase C (PKC) by DiC8 or the phorbol ester TPA. This would indicate a site for DA action distal to PKC. However, the stimulatory effect of arachidonic acid (AA; 50 microM) in perifusion was not reduced by DA (1 microM) or by APO, LY or BRCR in culture, which suggests a site for DA action proximal to AA formation. APO, LY and BRCR reduced GtH release in response to the Ca2+ ionophore A23187, however, their inhibitory effect was reversed by 10 microM ionomycin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1979

On the course and origin of cranial nerves in the teleost fish Gnathonemus determined by ortho- and retrograde horseradish peroxidase axonal transport.

By horseradish peroxidase (HRP) labelling the course and origin of the II-X cranial nerves are identified in the teleost fish Gnathonemus petersii. Roots as well as motor and sensory nuclei in the viscero- and somatomotor and somatosensory areas are localised. Earlier data of comparative and experimental anatomical observations are completed, partly confirmed or corrected.

Animals↗

PubMed1980

Glio-axonic junctional like complexes at the Mauthner cell's axon cap of teleosts: a possible morphological basis for field effect inhibitions.

Differentiated contacts were identified by electron microscopy between glia and axons as they enter the axon cap which surrounds the initial segment of the teleost's Mauthner cell. At these regions, the cleft of adjacent membranes is 20-25 nm wide and contains clods of electron-dense material with a pseudo-periodicity of 10-30 nm. These junctions, referred to as 'septate-like junctions', presumably contribute to the compartmentalization of the axon cap and, therefore, to its elevated resistivity which underlies the generation of field effect inhibitions.

Animals↗

PubMed1989

Calcitonin gene-related peptide-like immunoreactive fibres innervating the hypothalamic inferior lobes of teleost fishes.

The hypothalamic inferior lobes of 5 species of teleost fishes receive a prominent innervation by calcitonin gene-related peptide (CGRP)-like immunoreactive fibres. At electron microscopic level these contain immunostained dense-cored vesicles, and make synaptic connections with subependymal neurons surrounding the lateral recess. A proportion of the fibres may ascend from gustatory brainstem areas, consistent with a role for the inferior lobes as relay centres for integration of feeding and aggressive behaviour.

Animals↗

PubMed1991

Exocytotic release of neurotransmitters from nerve fibers in the endocrine pancreas (Brockmann body) of the teleost, Takifugu niphobles.

Exocytotic release of neurotransmitters was ultrastructurally investigated in the endocrine pancreas (Brockmann body) of the teleost, Takifugu niphobles. Exocytotic figures of large cored vesicles were found not only on the surface of nerve fibers facing the endocrine cells directly, but also on their surface facing the space of connective tissues including the blood capillaries. The results indicate that some 'neurotransmitters' are released non-synaptically in the endocrine pancreas and that some 'neurotransmitters' may enter the blood stream as 'neurosecretory hormones.'

Animals↗

PubMed1992

Cytochalasin inhibits light-dependent synaptic plasticity of horizontal cells in teleost retina.

Previous studies have shown that the horizontal cell-->cone photoreceptor negative feedback synapse in teleost fish retinae is 'plastic', being suppressed in the dark and potentiated by light adaptation. The possible involvement of filamentous actin in ultrastructural and electrophysiological aspects of this plasticity has been investigated using cytochalasins, which inhibit actin turnover, in the cyprinid fish (roach) retinae. Cytochalasin B or D (40 microM) inhibited both the light-dependent formation and maintenance of spinules, and enhancement of the feedback interaction involved in generation of biphasic spectral responses in horizontal cells. The results suggest that actin turnover is essential for both ultrastructural and electrophysiological plasticity of horizontal cell feedback and that spinules could mediate this dynamic interaction.

Animals↗

PubMed1992

cAMP-mediated second messenger mechanisms are involved in spinule formation in teleost cone horizontal cells.

A number of light adaptive changes of teleost horizontal cells are mediated by dopamine D1 receptors coupled positively with the cAMP second messenger system. Spinules, finger-like extensions from horizontal cell dendrites directed towards the cone pedicle cytoplasm, are formed in response to a stimulation of D1 receptors. We studied the second messenger mechanism associated with this process using isolated dark-adapted cyprinid retinae. Increasing intracellular cAMP concentrations by adding a membrane permeable analogue, or by stimulating the adenylate cyclase and simultaneously blocking the degradation of cAMP, resulted in a significant increase of spinule numbers in spite of the absence of light. In contradistinction to using isolated retinae for pharmacological experiments, injection of drugs into the vitreous had inconsistent or negative results.

1-Methyl-3-isobutylxanthine↗

PubMed1993

Gonadotropin-releasing hormone, a neuropeptide of efferent projections to the teleost retina induces light-adaptive spinule formation on horizontal cell dendrites in dark-adapted preparations kept in vitro.

The teleost retina receives efferent projections from neurons of the nucleus olfactoretinalis at the base of the olfactory bulbs. These fibres contain gonadotropin-releasing hormone (GnRH) immunoreactive material and are presynaptic to retinal dopaminergic interplexiform cells. We have incubated isolated dark-adapted retinae and eyecup preparations of roach with salmon-GnRH and found an increase in horizontal cell spinule numbers to 70% light-adaptive levels. This effect was blocked by addition of haloperidol to the incubation medium suggesting that GnRH acts via stimulation of the dopaminergic interplexiform cells. We conclude that GnRH containing efferent fibres are capable of inducing light-adaptive changes in the retina and discuss their implication in the control of endogenous rhythms.

Amino Acid Sequence↗

PubMed1994

Nitric oxide synthase in the brain of a teleost.

The presence and distribution of the nitric oxide (NO) converting enzyme, NO synthase (NOS), was investigated in the brain of a teleost, the Atlantic salmon. Both NOS immunoreactive and NADPH diaphorase positive, non-neuronal and neuronal cell bodies, fibers and putative nerve terminals were identified throughout the brain. Even so, the staining was not identical in all regions. NO, synthesized by NOS-like enzymes, may play an important role in a diversity of cellular mechanisms in the brain of the salmon, including in neural systems related to olfactory, visual, hypophysiotrophic, viscero-sensoric and motor functions.

Amino Acid Oxidoreductases↗

PubMed1978

Tissue alkaline phosphatase activity in selected freshwater teleosts.

1. Kinetic studies of tissue alkaline phosphatase activity were carried out on eight species of teleost fishes taken from the Mississippi River. 2. Liver alkaline phosphatase activity expressed in mumoles of p-nitrophenol released per minute per gram of protein were as follows: Micropterus salmoides, 20.31; Stizostedion vitreum, 19.22; Pomoxis nigromaculatus, 18.76; Lepisosteus platostomus, 16.26; Esox lucius, 16.14; Hiodon tergisus, 13.83; Ictalurus punctatus, 10.87; Aplodinotus grunniens, 7.94. 3. Specific activity of the kidney alkaline phosphatase was about ten times the level of liver alkaline phosphatase for the species examined.

Alkaline Phosphatase↗

PubMed1979

Enzymes of steroid hormone metabolism in ovarian tissue of teleosts.

1. Substrate-velocity kinetics and some other characteristics of three enzymes involved in steroid hormone metabolism in the ovary of the common carp, Cyprinus carpio and of the grey mullet, Mugil cephalus were determined. 2. Labeled steroid products of the enzyme reactions were identified by thin-layer and gas-liquid chromatographies, as well as by formation of derivatives. 3. 5 alpha-Steroid reductase of carp ovary was found to have a Michaelis-Menten constant undistinguishable from that of rat ovarian tissue, while the Km of the enzyme in mullet ovarian tissue was found to be different. 4. The Km of 20 alpha-hydroxysteroid dehydrogenase of mullet ovarian tissue was similar to the value reported for mammalian gonadal tissue, but the constant for 17 beta-hydroxy-steroid dehydrogenase in the carp ovary was different. 5. It is for the first time that these enzymes of steroid hormone metabolism have been quantitatively determined in teleost ovarian tissue.

17-Hydroxysteroid Dehydrogenases↗

PubMed1984

Characterization and function of isolated hemoglobins from the marine teleost Girella tricuspidata.

Five isohemoglobins were characterized from the marine teleost fish, Girella tricuspidata, using polyacrylamide gel electrophoresis and isoelectric focusing. O2-equilibrium (OEC) studies of the five components separated by column chromatography showed functional heterogeneity with respect to Hill's coefficient n, the O2 affinity, P50, and the Bohr coefficient phi, = delta logp50/delta pH. Recombination and examination of the isolates gave an OEC similar to that of "stripped" hemolysate and similar to a curve synthesized from a model incorporating the OEC parameters of the isoHbs.

Animals↗

PubMed1985

Plasma vitellogenin in landlocked Atlantic salmon (Salmo salar Ouananiche): isolation, homologous radioimmunoassay and immunological cross-reactivity with vitellogenin from other teleosts.

Vitellogenin was isolated by affinity chromatography and gel filtration from landlocked Atlantic salmon plasma. Vitellogenin was labelled with iodine-131 using iodogen and an homologous radioimmunoassay was developed. There was poor immunological cross-reactivity with vitellogenin or plasma from other teleosts. Parallelism of the vitellogenin standard to the displacement by plasma of vitellogenic salmon allowed the assay to be used to evaluate the seasonal concentration profile of vitellogenin in female adult salmon. Extracts of liver or ovary from female Atlantic salmon also yielded displacements parallel to the vitellogenin standard in the assay.

Animals↗

PubMed1985

Electrophoretic and immunological study of myosin light chains from freshwater teleost fishes.

White muscle myosin light chains from nine freshwater teleosts show a qualitative and quantitative variability on PAGE without phylogenetic correlation. They look different from their higher vertebrate counterparts mainly with regard to electric charge and relative amounts of alkali light chains corresponding to various contents of isoenzymic forms of white muscle myosin. Antibodies against carp white myosin LC1 recognize almost entirely white muscle LC1 from the other fishes and to a lesser degree LC1 from other muscles and vertebrates. The primary structure of this light chain is thus relatively constant. LC2 from carp cardiac muscle and mammalian slow and cardiac muscle do not react at all.

Animals↗

PubMed1986

Central nervous system myelin of teleosts: comparative electrophoretic analysis of its proteins by staining and immunoblotting.

CNS myelin was isolated from 24 teleostean fishes and the proteins were analyzed by staining and immunoblotting. All species showed a 36 K protein, two or more glycosylated hydrophobic intermediate protein (IP) components and several myelin basic protein bands (BP). The 36 K protein was specific for teleostean fishes. The IP and BP components displayed substantial variations in their proportions as well as in molecular sizes when comparing the different teleosts. This contrasts with CNS myelin proteins which appear more stable in terrestrial vertebrates.

Animals↗

PubMed1986

Activation of trout gill AMP deaminase by an endogenous proteinase--III. Comparative studies on the gill AMP deaminase from different fresh water and sea water teleosts.

The effects of monovalent cations and inorganic phosphate, on gill AMP deaminase, were compared in different fresh water and sea water stenohaline and euryhaline Teleosts. Generally, sea water species displayed a lower sensitivity to these effectors than fresh water species. During salinity changes, the sensitivity of gill AMP deaminase to cations and phosphate were modified proportionally to the tolerance of a given species to variations of environmental salinity. In particular, these parameters were modified in the weak euryhaline, Salmo gairdneri, but not in the real euryhaline, Anguilla anguilla. In sea water adapted trout, the appearance of a modified AMP deaminase form, with similar properties to that found in sea water species, is suggested. When compared with the conclusions from the preceeding papers [Raffin (1986) Comp. Biochem. Physiol. 85B, 157-162; 85B, 163-171], the results suggest that modification of gill AMP deaminase by limited proteolysis should be a rather general adaptation mechanism to stress.

AMP Deaminase↗