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PubMed2000

Binding of xenobiotics to hepatic estrogen receptor and plasma sex steroid binding protein in the teleost fish, the common carp (Cyprinus carpio).

Competitive receptor binding assays have been suggested as an in vitro screening tool for assessing the activity of alleged estrogenic substances. In this study, we determined the ability of steroidal and nonsteroidal substances to inhibit the binding of [(3)H]17 beta-estradiol (E2) to the hepatic estrogen receptor (ER) and the plasma sex steroid binding protein (SBP) of the teleost fish, the common carp (Cyprinus carpio). The objectives of the study were (1) to characterize ER binding in the liver cytosol of male and female carp, (2) to establish complete [(3)H]E2 displacement curves from carp ER for a range of natural and xenobiotic substances and to compare the ligand data of carp ER with published data from other vertebrate species to reveal possible species differences, and (3) to determine the interaction of natural and xenobiotic substances with the steroid binding site of SBP in carp plasma. The results indicate the presence of a single class of estrogen binding sites with high affinity and limited capacity in liver cytosol of carp. The various test agents showed partly quantitative differences in their binding affinities, with the xenobiotics generally showing limited ability to displace [(3)H]E2 from the hepatic ER or from plasma SBP of carp. However, we found no evidence that a compound is an ER ligand exclusively in one species. The findings of this study indicate that interspecies extrapolation of steroid receptor binding data is possible on a yes/no basis but not on a quantitative basis.

Animals↗
PubMed2000

Gonadotropin-releasing hormone-immunoreactive neurons and associated nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in the brain of a teleost, Rhodeus amarus.

Using combined nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd) histochemistry and salmon gonadotropin-releasing hormone (sGnRH) immunocytochemistry, it is reported for the first time that possible potential contacts occur between the nitric oxide (NO)- and the GnRH-containing neurons in the brain of a freshwater teleost, Rhodeus amarus. GnRH-immunoreactive (ir) neurons were observed in the olfactory nerve (OLN), olfactory bulb (OB), medial olfactory tract (MOT), ventral telencephalon (VT), nucleus preopticus periventricularis (NPP), nucleus lateralis tuberis (NLT), and midbrain tegmentum (MT). Although NADPHd neurons were widely distributed in the brain, only those having an association with GnRH-ir neurons are described. Based on the nature of the association between the GnRH and the NADPHd neurons, the former were classified into three types. The Type I GnRH neurons were characterized by the presence of NADPHd-positive granules in the perikarya and processes and occurred in the OLN, OB, MOT, and VT. The Type II GnRH neurons, having soma-soma or soma-process contacts with the NADPHd neurons, were restricted to the MT; the long processes of NADPHd cells crossed over either the perikarya or the thick processes of GnRH cells. However, the Type III GnRH neurons, found in the NPP and NLT, did not show direct contact, but a few NADPHd fibers were present in the vicinity. The terminal-soma contacts in the olfactory system and the VT and the soma-soma contacts in the MT represent the sites of possible potential contacts indicating a direct NO involvement in GnRH function, although NO action by diffusion remains possible. NO may influence the NPP and NLT GnRH cells by diffusion only, since a direct contact was not observed.

Animals↗
PubMed2001

Glucagon-like immunoreactivity in the forebrain and pituitary of the teleost, Clarias batrachus (Linn.).

The organization of glucagon-like immunoreactivity (GLI) in the olfactory system, forebrain, and pituitary was investigated in the teleost Clarias batrachus. Weak to moderate GLI was seen in some olfactory receptor neurons and basal cells of the olfactory epithelium. Intense GLI was seen in the olfactory nerve fascicles that ran caudally to the bulb, spread over in the olfactory nerve layer, and profusely branched in the glomerular layer to form tufts organized as spherical neuropils; some of the immunoreactive fibers seem to closely enfold the mitral cells. In the inner cell layer of the bulb, some granule cells were intensely immunoreactive. Although there were thick fascicles of immunoreactive fibers in the medial olfactory tracts (MOT), the lateral olfactory tracts were generally devoid of immunoreactivity. Immunoreactive fibers in the medial olfactory tract penetrated into the telencephalon from its rostral pole and entered into the area ventralis telencephali/pars ventralis where the compact fiber bundles loosen somewhat and course dorsocaudally into the area ventralis telencephali/pars supracommissuralis just above the anterior commissure. While some immunoreactive fibers decussated in the anterior commissure, fine fibers were seen in the commissure of Goldstein. Isolated immunoreactive fibers of the medial olfactory tract were traced laterally into the area dorsalis telencephali/pars lateralis ventralis and mediodorsally into the area dorsalis telencephali/pars medialis. However, a major component of the MOT continued dorsocaudally into the thalamus and terminated in the habenula. Two immunoreactive neuronal groups and some isolated cells were seen in the periventricular region of the thalamus. Although nucleus preopticus showed no immunoreactivity, some neurons of the nucleus lateralis tuberis displayed moderate GLI. Several immunoreactive cells were seen in the pars intermedia of the pituitary gland; few were encountered in the rostral pars distalis and proximal pars distalis. Immunoreactive fibers were seen throughout the pituitary gland.

Animals↗
PubMed1993

Sex steroid levels in Porichthys notatus, a fish with alternative reproductive tactics, and a review of the hormonal bases for male dimorphism among teleost fishes.

Plasma levels of 11-ketotestosterone, 11-beta-OH-testosterone, testosterone, and 17-beta-estradiol were measured in reproductive Porichthys notatus, a teleost fish with two male morphs and alternative reproductive tactics. The two male types had contrasting androgen profiles. 11-Ketotestosterone was the predominant androgen in the Type I male morph which acoustically courts females, excavates nests, and guards eggs. Yet testosterone was predominant in the plasma of the Type II male morph which neither courts females nor nests, but instead parasitizes Type I males with sneak or satellite spawning tactics. The Type I-Type II male divergence in reproductive tactics and androgen levels is paralleled by dimorphisms in the vocal system, in body size, and in relative testis size. A review of endocrine data from six different species with male dimorphism shows consistent differences between morphotypes and a striking pattern: 11-ketotestosterone levels are uniformly elevated in each "courting male" morphotype relative to its "noncourting" conspecific. This cross-species pattern may reflect the behavioral, gonadal, or morphological differences which characterize the two morphotypes. At this point, the morphological interpretation is favored.

Animals↗
PubMed1995

Teleost fish islets: a potential source of endocrine tissue for the treatment of diabetes.

Anatomical separation of pancreatic islets in some teleost fish makes them a useful source of pancreatic endocrine tissue. Islets were harvested from tropical Tilapia fish (Oreochromis nilotica) and cultured for 24 hr at 37 degrees C. Eight athymic nude mice were rendered diabetic by streptozotocin (STZ) and transplanted under the kidney capsule with fish islets. After transplantation (Tx), nonfasting blood glucose (n-FBG), which was in all recipients > 450 mg/dl, decreased to < 100 mg/dl. At 4 and 7 weeks post-Tx, the intraperitoneal (ip) glucose tolerance test was performed in the normoglycemic Tx mice and in six normal controls. In controls, K value (percentage of decline in blood glucose/min) was 1.076 +/- 0.383 and in Tx mice it was 0.956 +/- 0.336 and 0.869 +/- 0.483 at 4 and 7 weeks, respectively (P = n.s.). Nephrectomy raised the n-FBG to pre-Tx levels. On immunohistochemistry, recipient's pancreata showed atrophic islets with no beta-cell granules, while the islet-bearing kidneys had distinct beta-cells under their capsules. Alginate-embedded fish islets were encapsulated in permselective (25-kDa) cellulose membranes and implanted ip in six STZ-diabetic nude mice. On the following day, all recipients became normoglycemic and their n-FBG remained normal for 7 days. In one animal, the n-FBG was < 200 mg/dl for 14 days and subsequent removal of the capsule raised the n-FBG to the pre-Tx level. Finally, it was found that fish islets can be cultured at 37 degrees C for extended periods of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Physical constraints on body size in teleost embryos.

All members of the subphylum "Vertebrata" display the characteristics of the vertebrate body plan. These characteristics become apparent during the phylotypic period, in which all vertebrate embryos have a similar body shape and internal organization. Phylogenetic constraints probably limit the morphological variation during the phylotypic period. Physical laws, however, also limit growth and morphogenesis in embryos. We investigated to what extent oxygen availability-as a physical constraint-might limit morphological variation during embryonic development. This paper gives an analysis of time-dependent diffusion into spherical embryos without a circulatory system. Equilibrium appeared to settle in about 1.5 min in running water and in about 10min in stagnant water. Hence, steady-state conditions were assumed and expressions for maximum body size were obtained for spherical, cylindrical and sheet-like embryos in running water and spherical embyros in stagnant water. Predictions of the model based on literature data suggest that in running water-both for spherical, cylindrical and sheet-like embryos-diffusion alone suffices to cover the oxygen needs of a teleost embryo in its phylotypic period. The size of carp (Cyprinus carpio) and African catfish (Clarias gariepinus) embryos is very close to the predicted maximum. This suggests that in these species the development of a functional circulatory system is correlated with the onset of oxygen shortage. Oxygen availability is therefore a potentially important physical constraint on embryonic morphology, though in most species the circulatory system becomes functional well in advance of the onset of oxygen shortage and other demands than oxygen delivery (e.g. nutrient distribution, waste disposal, osmoregulation) might require the development of a circulatory system.

Animals↗
PubMed1998

Chlorzoxazone metabolism by winter flounder liver microsomes: evidence for existence of a CYP2E1-like isoform in teleosts.

Winter flounder (Pleuronectes americanus) liver microsomes metabolized chlorzoxazone (CZX), a CYP2E1 (cytochrome P450 2E1)- specific substrate, to a single product, 6-OH CZX. The liver microsomal fraction had the highest level of activity, which varied among fish, ranging from 60 to 220 pmol/mg/min. CZX metabolism was linearly related to microsomal protein and dependent on NADPH. The optimal pH range for this activity was from 7.2 to 8.0. Maximal activity was found at 18-22 degreesC (154 +/- 62 pmol/mg/min) but was detectable at all temperatures tested. CZX 6-hydroxylation displayed first-order kinetics as shown by Lineweaver-Burk plots. The average apparent Km, 280 microM, was higher than that reported for human liver microsomes but similar to the Km determined for human CYP2E1 expressed in vaccinia virus. Vmax values ranged from 65 to 141 pmoles/mg/min. The CYP2E1-specific inhibitors, diethyldithiocarbamate (DDC) and aniline, significantly reduced 6-OH CZX production by 80 and 35%, respectively. 7,8-Benzoflavone and ethoxyresorufin, both CYP1A-specific inhibitors, did not significantly inhibit CZX metabolism nor did trioleandomycin (TAO) a CYP3A-specific inhibitor. Diethyldithiocarbamate (DDC), at 50 microM, had no significant effect on winter flounder liver microsomal ethoxyresorufin-O-deethylase activity (EROD), a CYP1A-specific activity. 7,8-Benzoflavone, at 10 microM, inhibited EROD activity by 60%. This is the first report of CYP2E1 activity in teleost liver microsomes.

Aniline Compounds↗
PubMed1990

Structure of the corpuscles of Stannius in the euryhaline teleost Takifugu niphobles (Tetraodontiformes, Teleostei), with special regard to vascularization and extravascular channel system.

Vascularization and the extravascular channel system of the corpuscles of Stannius in a euryhaline teleost, Takifugu niphobles, were studied by scanning electron microscopy of the vascular corrosion cast, and histochemistry of exogenously injected horseradish peroxidase as a macromolecular tracer. The corpuscles were apposed to the caudal part of the ureter, away from the mesonephric kidney, and were supplied with arterioles from the genital artery running ventrally as a ramus of the dorsal aorta. Elaborate capillary networks irrigating the glandular lobules were collected by the venules to drain into the posterior cardinal veins. Electron microscopic examination of the glands demonstrated two types of secretory cells, type-1 cells with large granules, and type-2 cells with smaller granules. The type-1 cells, predominating in the gland, occasionally showed exocytosis of the secretory granules, mainly into intercellular spaces between adjoining cells. Exocytosis was also evident in the type-2 cells. The tracer molecule injected was visualized histochemically within the capillary lumina and intercellular spaces throughout the gland. The labelled spaces intercommunicated with each other to form an extensive extravascular channel system as a diffusing pathway within the gland. The possible role of this system in hormone transport and/or storage was discussed.

Animals↗
PubMed1995

Structure and evolution of teleost mitochondrial control regions.

We amplified and sequenced the mitochondrial control region from 23 species representing six families of teleost fish. The length of this segment is highly variable among even closely related species due to the presence of tandemly repeated sequences and large insertions. The position of the repetitive sequences suggests that they arise during replication both near the origin of replication and at the site of termination of the D-loop strand. Many of the conserved sequence blocks (CSBs) observed in mammals are also found among fish. In particular, the mammalian CSB-D is present in all of the fish species studied. Study of potential secondary structures of RNAs from the conserved regions provides little insight into the functional constraints on these regions. The variable structure of these control regions suggests that particular care should be taken to identify the most appropriate segment for studies of intraspecific variation.

Animals↗
PubMed1990

A study of the morphology of the gills of an extreme alkalinity and hyperosmotic adapted teleost Oreochromis alcalicus grahami (Boulenger) with particular emphasis on the ultrastructure of the chloride cells and their modifications with water dilution. A SEM and TEM study.

The general gill morphology of Oreochromis alcalicus grahami, a teleost adapted to high salinity and hyperosmosis, is basically similar to that of other teleostean fish. The species has four pairs of gill arches, all of which have well developed filaments. Each of the arches (holobranchs) has two rows of filaments (hemibranchs). Bilaterally situated secondary lamellae branch from the central axis of the filaments. The lamellae reach their maximum size at the middle of the filament, gradually decrease in size and eventually disappear towards the tip of the filament, which is bare. The leading edge of the gill filament and the immediate interlamellar space is covered by a stratified epithelium consisting of pavement cells, mucous cells, chloride cells and undifferentiated cells. The surface of these cells is made up of concentric microridges. The chloride cells were found only on the primary epithelium (filamental epithelium) and very rarely on the secondary epithelium (lamellar epithelium). Two types of chloride cells were observed in the gills of Oreochromis. The superficial chloride cells have fewer mitochondria concentrated towards the basal aspect of the cell, and a network of tubules towards the apical surface and are less electron dense. These cells intercommunicate with the water through an apical pore. The deep chloride cells have numerous diffuse mitochondria intercalated between a fine profuse tubular network and are more electron dense. These cells are covered by one or more layers of pavement cells and thus do not have access to the external surface. After gradual dilution of the lake water in which the fish were kept, both types of chloride cells remained topographically and ultrastructurally distinct. However, in both kinds of cell the mitochondria decreased in number and size. Initially there was an increase in the diameter and the degree of interdigitation of the tubules followed by a gradual decrease. An increase in the quantity of rough endoplasmic reticulum, particularly at the perinuclear region of the cell, was noted. The morphometric analysis of the branchial system indicated that the gills of Oreochromis are well adapted for gas exchange by having numerous and relatively long gill filaments with a high lamellar density. These features provide a large surface for gas exchange which, when coupled with the notably thin water-blood barrier of an average thickness of only 0.83 micro, would facilitate efficient absorption of oxygen by the gills. Oreochromis alcalicus was observed to be incapable of adapting to freshwater. This may have been due to the progressive degeneration of the chloride cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1983

Ultrastructure of the kidney of the marine teleost Sparus auratus: the renal corpuscle and the tubular nephron.

The ultrastructure of the renal corpuscle and tubule of Sparus auratus is described. The parietal epithelium in Bowman's capsule is flattened with occasional cilia; podocytes are large with bundles of perinuclear microfilaments, a large vacuole and occasional cilia; a filtration slit membrane can sometimes be identified; mesangial cells are placed peripherally and among the walls of the capillaries. The neck segment is short and ciliated; it lacks the mucous cells which appear in some teleosts. The first proximal segment has columnar cells with a well developed brush border, and some cilia, large light vacuoles and many lysosomes appear in the apical zone; the second proximal segment has taller cells than the former, which appear with a less dense brush border, containing numerous multivesicular bodies; the third proximal segment, which has cells similar to the previous ones, possesses a less developed brush border and numerous mitochondria scattered all over the cytoplasm. No distal tubule is present. There is a collecting tubule with columnar cells with few microvilli and some apical mucin granules which empty into the collecting duct.

Animals↗
PubMed1981

Developmental stages and localization of peroxidatic activity in the leucocytes of three teleost species (Cyprinus carpio L.; Tinca tinca L.; Salmo gairdneri Richardson).

The ultrastructural localization of peroxidase (PO) in the leucocytes of three teleosts (Cyprinus carpio L., Tinca tinca L., Salmo gairdneri R.) has been investigated using the 3,3'-diaminobenzidine method. In the heterophilic granulocytes the granules show a species specific structure and are PO-positive at pH 7.6. They can be traced back to small granules arising near the Golgi apparatus (GA) in the promyelocyte. They coalesce to form larger granules and gradually change into the mature type. Myelocytes contain small unreactive granules, and these represent a second granule population. Eosinophils contain one PO-positive granule type (at pH 9), and these granules show a varying density during cell maturation. Basophils are present only in the Cyprinid species, and contain unreactive granules originating from precursors displaying a weakly positive reaction at pH 7.6. The active secretory organelles (RER, GA) are PO-negative, except for a weekly positive reaction in the flocculent matrix of the inner G-cisternae. In promonocytes and monocytes the granules are unreactive, but in the macrophages PO-positive staining occurs in a few small to medium sized granules, and in large vacuoles. A least some of these latter are apparently derived from phagolysosomes containing digested erythrocytes. Thrombocytes and lymphocytes are unreactive. The successive development of PO-positive and negative granule populations in the heterophils, and the PO-reactivity of eosinophils and basophils, show some similarities to the corresponding cells in higher vertebrates, but an analogous PO-positive ("azurophil") granule type in monocytes seems to be absent.

Animals↗
PubMed1981

Ultrastructural study of the endothelial cells in teleost liver sinusoids under normal and experimental conditions.

The ultrastructure of the endothelial cells of liver sinusoids was studied in the teleost, Pimelodus maculatus. These cells have the ability to form pinocytotic vacuoles, starting with the formation of marginal folds. The latter occur in many cells after stimulation by India ink injections and ink particles are ingested by pinocytosis and by micropinocytosis. Desmosomes, structures rarely described between liver sinusoidal endothelial cells, are present in this species.

Animals↗
PubMed1981

Ultrastructural study of Kupffer cells in teleost liver under normal and experimental conditions.

The Kupffer cells in the liver of the teleost fish, Pimelodus maculatus, are attached by desmosomes to the endothelial cells lining the sinusoids. These provide a strong attachment allowing them to resist the passage of blood. Following perfusion with India ink, both endothelial and Kupffer cells ingest India ink particles by pinocytosis and micropinocytosis. It is suggested that both cell types may represent two different functional states of the same cell.

Animals↗
PubMed1986

Ultrastructural characterization of neurosecretory fibres immunoreactive for vasotocin, isotocin, somatostatin, LHRH and CRF in the pituitary of a teleost fish, Poecilia latipinna.

Using the electron-microscopic immunogold method, vasotocin, isotocin, somatostatin (SRIF), gonadotrophin-releasing hormone (LHRH) and corticotrophin-releasing factor (CRF)-like immunoreactivities were localized in separate neurosecretory fibres in the pituitary of a teleost fish Poecilia latipinna. Antigenicities were preserved in sections of conventionally fixed tissue, except in the case of LHRH and CRF-like substances which were sensitive to osmium postfixation. Under the same fixation conditions, ultrastructural differences were observed between the 5 fibre types, and morphometric analysis of their granule sizes revealed significant differences in mean diameter except between vasotocin and isotocin fibres. Terminal-like regions of each type were identified on blood vessels, glial cells or other fibres in the neurohypophysis, on the basement lamina of the adenohypophysis, or directly on adenohypophysial endocrine cells. The fibres containing the two neurohypophysial hormones, originating from separate preoptic perikarya, were intermingled with, and may form endings near all the adenohypophysial cell types except those secreting prolactin. Although both types had similar mean granule diameters, the granules in the vasotocin fibres (mean 135 nm) were markedly less electron dense than those in the isotocin fibres (mean 140 nm). SRIF-immunoreactive fibres (mean 101 nm) appeared to form synapse-like endings on the somatotrophs, and a few thyrotrophs in the proximal pars distalis, and near the pars intermedia cells. An LHRH-positive type (mean 103 nm) contacted only the gonadotrophs of the proximal pars distalis. The rarer CRF-like fibres (mean 116 nm) appeared to project mainly towards the pars intermedia, but a few appeared to terminate rostrally near the adrenocorticotrophic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Immunohistochemical localization of urotensin I and other neuropeptides in the caudal neurosecretory system of three species of teleosts and two species of elasmobranchs.

In three species of teleosts - carp Cyprinus carpio; grass carp Ctenopharyngodon idella; and crucian carp Carassius auratus - the caudal neurosecretory system displays small, medium-sized and large neurons. Urotensin I (UI)-immunoreactive and UI-nonreactive neurons were found in all three groups; in general, the number of the latter neurons exceeded that of the former. Noteworthy are: (i) UI-immunoreactive fibers in the caudal spinal cord and (ii) dense accumulations of UI-immunoreactive product around the capillaries of the urophysis. In two species of elasmobranchs-cat shark Heterodontus japonicus and swell shark Cephaloscyllium umbratile - neurosecretory neurons decreased in size in rostro-caudal direction. Most of the neurosecretory perikarya, their axons and the corresponding neurohemal areas were UI-immunoreactive, but a small number of secretory neurons was devoid of immunoreaction. Oxytocin, arginine vasopressin, substance P, somatostatin, neurotensin, vasoactive intestinal polypeptide and gastrin-releasing peptide were not detected in the caudal neurosecretory system of the carp.

Animals↗
PubMed1993

In vitro immunomodulation by pentachlorophenol in phagocytes from an estuarine teleost, Fundulus heteroclitus, as measured by chemiluminescence activity.

Chemiluminescence (CL) was used to assay effects of pentachlorophenol (PCP) on the production of reactive oxygen intermediates (ROIs) generated by leukocytes from an estuarine teleost, Fundulus heteroclitus. Two parameters were measured during the phagocytically-induced respiratory burst: peak CL (maximal value) and total CL (temporal summation of induced values). Phagocytes obtained from the pronephros were incubated in the presence of sublethal doses of analytical (A-) or technical (T-) grades of PCP. Technical PCP has been reported to be more highly immunosuppressive than A-PCP in mammals; this effect was attributed to dioxins and other contaminants produced during manufacture. In this fish, both grades of the compound produced significant dose-dependent inhibition of peak and total CL. However, there were few significant differences between the effects of the two PCP grades on the magnitude of the CL responses at identical, sublethal concentrations, although T-PCP did produce a more marked reduction in the relative level of leukocytic CL as a function of dose than did A-PCP. Because of the probable roles of ROIs in antimicrobial blood cell-mediated mechanisms, reduced CL activity was interpreted as an indication of xenobiotic-induced immunosuppression.

Adjuvants, Immunologic↗
PubMed1985

Immunoreactive neuronal pathways of growth hormone-releasing hormone (GRH) in the brain and pituitary of the teleost Gadus morhua.

Using an antiserum directed against the C-terminus of hGRH(1-44)NH2 and another recognizing the mid portion to C-terminal of hGRH(1-40)OH, we identify two immunocytochemically distinct GRH-immunoreactive systems in the brain of the codfish, Gadus morhua. The antiserum directed against GRF(1-44)NH2 stains cell bodies exclusively in the rostral pars distalis. The other antiserum immunoreactive with GRF(1-40)OH reacts with a population of parvocellular and magnocellular neuronal cell bodies in the hypothalamus and with two major axonal pathways which project toward the median eminence and terminate primarily in the pars nervosa. These results indicate the presence of at least two forms of hGRH-like peptides in the teleost which may have different roles in the regulation of pituitary function.

Animals↗