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At least 505 records · Page 28Linked to original sources
PubMed1984

Electron microscopic study of teleost (Pimelodus maculatus) pancreatic islet cells.

The endocrine pancreas of the freshwater teleost Pimelodus maculatus was studied by electron microscopy. Based on the granule morphology 2 cell types were described: Secretory granules of type I cells are rounded, nearly completely filling the limiting membranous sac which measures from 120 to 150 nm in diameter; the type II granules are also rounded and measure from 220 to 270 nm in diameter; they consist of an eccentrical electron dense core separated from the limiting membrane by a wide electron lucent halo. These characteristics are correlated with those found in other teleosts.

Animals↗
PubMed1984

Variation in lengths of ciliary bundles on hair cells along the macula of the sacculus in two species of teleost fishes.

The sacculus is one of the end-organs of the inner ear. In many teleost fishes the sacculus is considered the major auditory organ. We have used scanning electron microscopy to examine the lengths of the ciliary bundles on hair cells in the sensory macula of the sacculus in two diverse species of teleosts. The data are presented in a form allowing direct comparison with recent data on a wide range of tetrapod auditory organs. In goldfish, the ciliary bundles are significantly longer in the caudal part of the macula than in the rostral part, but the kissing gourami shows nearly uniform ciliary bundle heights along its entire length. Based on limited data from the literature, the part of the macula responsive to lower frequencies is the part containing these taller bundles in goldfish, suggesting a parallel with the gradient of ciliary bundles and frequency response found in tetrapods.

Animals↗
PubMed1983

Tubulated bodies in teleost (Pimelodus maculatus) endothelial cells.

In the present report tubulated granules are described for the first time in a freshwater teleost (Pimelodus maculatus) endothelial cells. Some ultrastructural characteristics as well as the localization and distribution suggest that tubulated bodies represent the teleost counterpart of the Weibel-Palade bodies described in other animal classes.

Animals↗
PubMed1983

Morphologic changes in teleost primary and secondary retinal cells following brief exposure to light.

Light adaptive morphologic changes in the teleost retina, such as movements of rods, cones, and epithelial pigment and spinule formation on horizontal cell terminals, are normally associated with continual exposure to light. Depending on a variety of factors these processes are generally completed within 30-60 min. In this report we show that a brief exposure to light (1-2 min) preceded and followed by darkness is sufficient to elicit these changes in four species of teleost; the trout (Salmo gairdneri), the tench (Tinca tinca), the carp (Cyprinus carpio), and the goldfish (Carassius auratus). A brief pulse is as effective in causing cone migration and an increase in the number of spinules as continual exposure; however, it is sometimes less effective in causing pigment migration. The photomechanical changes following a brief period of light are always completed more quickly and show greater species variability than the formation of spinules. These results show that the various morphologic manifestations of light adaptation are autonomous processes that need only a short pulse of light to trigger the whole sequence of events. This is of interest when considering their control mechanisms and may have consequences for physiologic work involving experiments on dark-adapted eyes.

Adaptation, Physiological↗
PubMed1980

Teleost kidney in evaluation of xenobiotic toxicity and elimination.

The unique anatomy of the marine teleost kidney and the development of techniques to take advantage of that anatomy are discussed and several examples of their use to study xenobiotic excretion and toxicity are documented. These include: 1) characterization of renal organic anion transport, the system that mediates excretion of many such compounds and their metabolites; 2) assessment of the relative roles of transport, metabolism, and plasma binding in xenobiotic excretion; 3) examination of the morphological aspects of cellular injury; and 4) analysis of subcellular sites of heavy metal toxicity. Also presented are applications of new techniques in membrane physiology to the study of the effects of xenobiotics. It is suggested that continued application of the comparative approach, as exemplified by the use of the marine teleost kidney, will provide powerful and versatile tools for investigation of fundamental biological processes and the interactions of foreign compounds with those processes.

Animals↗
PubMed1980

Glucose metabolism in the cornea and lens in elasmobranchs, teleosts and mammals: response to thiol-oxidation.

Various structural and metabolic adaptations that have occurred in elasmobranchs, in salt and fresh water teleosts, and in mammals have enabled these species to adapt to varied environments. In all cases the corneas of these species remain transparent and expend metabolic energy to maintain this transparency. The studies reported in this paper describe the structural and the metabolic adaptations that have occurred in these corneas. Included are measurements of corneal oxygen consumption, Q10 and corneal hydration. Thiol-oxidation of the intracellular glutathione with diamide has been shown to produce marked stimulation of the hexose-monophosphate shunt in the component layers of the cornea and the lens of rabbit, dogfish, and sculpin. Activities of glycolytic, citric acid cycle, and pentose phosphate shunt enzymes in the corneal and muscle tissue were also studied. Species variations were found between elasmobranchs, marine teleosts, and rabbits. In each of these species, the corneal endothelium was distinguished from the epithelium by much lower enzyme activities. It can be concluded that the enzyme activities and metabolic differences represent functional adaptations that have occurred to insure transparency under these extremely varied osmotic conditions.

Adaptation, Physiological↗
PubMed1994

Fine structure of the nephron in the euryhaline teleost, Oreochromis niloticus.

Ultrastructural studies were carried out on the nephron of a euryhaline teleost, Oreochromis niloticus. The nephron consisted of a renal corpuscle, neck segment, bisegmental proximal tubule and a distal tubule. Renal corpuscles displayed a trilaminate structure of fenestrated endothelium, triple layered basement membrane and a highly branched podocyte layer. Neck segments consisted of low cuboidal cells with apical cilia and few vacuoles. Proximal tubules were made up columnar cells with apical brush border. The initial part of the proximal tubule (PI) was characterized by a well developed endocytic apparatus which was absent in the next part (PII). Distal segments comprised of low columnar cells with scanty or no microvilli and an extensive system of basolateral membrane infoldings associated with mitochondria. These findings have been discussed in relation to renal function in fresh water euryhaline teleosts.

Adaptation, Physiological↗
PubMed1975

Immunohistological demonstration of insulin and glucagon in islet tissue of reptiles, amphibians and teleosts using epoxy-embedded material and antiporcine hormone sera.

Islet tissue from 2 reptilian, 5 amphibian and 7 teleost species was fixed in glutaraldehyde, embedded in epoxy-resin, stored for up to 3 years, cut in ultrathin sections and stained with the indirect immunofluorescent technique for insulin and glucagon following removal of the plastic. The antisera were directed against porcine insulin and glucagon, or FITC labeled and directed against the globulin fraction of the producer species. Positive results were obtained in species from all vertebrate classes investigated. Insulin demonstration in teleosts was particularly difficult.

Amphibians↗
PubMed1995

Structure and organization of the isotocin and vasotocin genes from teleosts.

Oxytocin and vasopressin are structurally related mammalian neurohypophysial hormones with distinct physiological activities. Homologues of these two hormones are found in all vertebrate groups except the primitive cyclostomes in which only a vasopressin-like hormone has been reported so far. Genes encoding the mammalian oxytocin and vasopressin hormone precursors exhibit a similar genomic organisation, and are closely linked (3.5 kb to 12 kb apart) in a tail-to-tail manner suggesting a common evolutionary origin. However, no linkage among genes of the vasopressin/oxytocin family has been demonstrated in any of the lower vertebrates. The Japanese pufferfish, Fugu rubripes, has been shown to have a very compact genome of about 400 Mb with very few repetitive sequences. We used this model vertebrate genome to analyse the genomic organisation of vasotocin and isotocin genes, the teleost homologues of vasopressin and oxytocin. We have cloned and mapped the vasotocin/isotocin locus in Fugu and obtained complete nucleotide sequences of the vasotocin and isotocin genes. The coding sequences of the Fugu vasotocin and isotocin genes are interrupted by two introns at identical positions, similar to their homologues in higher vertebrates. The deduced amino acid sequences as well as the coding sequences of the two genes show high homology in the neurophysin region. Furthermore, the two genes are linked in a tandem manner with an intergenic region of about 20 kb. Random sequencing has shown that there are at least two known vertebrate genes in the intergenic region. Genomic organisation of the Fugu vasotocin/isotocin locus suggests that the teleost vasotocin and isotocin genes have evolved from a common ancestor through tandem duplication and that this locus seems to have undergone a localised reorganisation during vertebrate evolution.

Amino Acid Sequence↗
PubMed1977

The telencephala of Division I of the teleost fishes.

A comparative neuroanatomical investigation of the telencephala of Division I of teleost fishes (Greenwood, Rosen, Weitzman, and Myers, 1966) has demonstrated that homologies with other vertebrates can be made on the basis of the relationships of commonly recognized fiber bundles such as the olfactory tracts, forebrain bundles and commissures as well as those of cell types in the nuclear regions. A description and illustrations of the telecephalon of a typical representative brain (American eel, Anguilla rostrata) of Division I are presented with comparisons with the other elopomorphs and with the clupeomorphs. Although the brains may differ in gross appearance, all have certain unique microscopic configurations. They lack lateral ventricles and have a dorsal membrane as do all actinopterygeans. The brains of these fishes characteristically have (1) apposed sessile (or attenuated penduncluar) olfactory bulbs (2) which lack the typical vertebrate laminar pattern, (3) the preoptic region is unusually large although (4) the recess may not extend rostral to the anterior commissure, (5) the striatal and amygdalar areas are large and especially well differentiated, and (6) a nucleus glomerulosus is lacking. Other fishes differ from those in Division I in one or more of these anatomical features. These criteria may be used to differentiate teleosts of Division I from those of other Divisions.

Amygdala↗
PubMedDate not supplied

[Solubilization of the AMP deaminase in the muscles of the teleost fish Scorpaena].

A considerable amount of AMP deaminase (AMPDA) in animal muscles is linked with myofibrils. This link is disturbed with growth of the ionic strength. A smooth increase of AMPDA solubilization has been showed in experiments with rabbit muscles when KCl concentration grew from 0 to 500 mM. Earlier we showed at trout muscles that an increase in KCl concentration from 0 to 200 mM in the homogenization medium induced growth of the bound enzyme portion followed by its decrease at the range of KCl concentrations 300-500 mM. Similar results were obtained in experiments with the sea scorpion muscles, which shows specific character of AMPDA interaction with myofibrils in teleost fish muscles. Comparison of the pH influence on AMPDA extraction from Scorpaena and rabbit muscles supported the idea on the specific character of this enzyme binding in the teleost muscles.

AMP Deaminase↗
PubMed1997

Morphometry of the kidneys of fresh water percoid and ostariophysian teleosts.

Kidneys of four fresh water teleost species representing percormorpha (Oreochromis niloticus and Micropterus salmoides) and Ostariophysi (Cyprinus carpio and Clarias mossambicus) were studied for quantitative structural characteristics using tissues fixed by perfusion. The renosomatic index (weight of kidney/weight of fish) was higher in the ostariophysian than percoid fish (p < 0.05) but values of volume of nephronic tissue/body weight were not significantly different. Results obtained by point counting morphometry showed that the kidneys of the percoid species were made up of 56.85-64.4% nephronic tissue, 30.45-32.47% blood vessels, 2.84-8.20% ureter and ureteral ducts and 2.07-2.48% connective tissue. The kidneys of the osariophysian species comprised of 35.27-36.71% nephronic tissue, 27.86-29.29% blood vessels, 1.59-4.20% ureter and its ducts, 29.07-29.51% interstitial cells and 2.70-3.60% connective tissue. The mean values for the volume proportions of the components of nephronic tissue were not significantly different in the percoids and ostariophysians and they were; renal corpuscles 3.84-6.54%, neck segments 0.50-1.11%, proximal segments 67.17-69.72%, distal segments 18.16-20.55%, and collecting tubule-collecting duct (CT-CD) system 5.66-7.41%. These results show that the quantitative structural characteristics of the kidneys of fresh water species from different orders are quite similar and emphasise the all persuasive influence of the environment on renal structure and function in teleosts.

Adaptation, Physiological↗
PubMed1997

Temporal expression pattern of insulin-like growth factor mRNA during embryonic development in a teleost, rainbow trout (Onchorynchus mykiss).

The appearance of insulin-like growth factor I (IGFI) and II (IGF-II) mRNA was studied during rainbow trout embryonic development. Reverse transcription-polymerase chain reaction (RT-PCR), followed by Southern blotting and high-stringency hybridization with rainbow trout IGF-I and IGF-II cDNA probes, was used to detect all four forms of IGF-I mRNA and one form of IGF-II mRNA from whole-embryo total RNA isolated from a staged series. IGF-I and IGF-II mRNA were detected in unfertilized eggs. IGF-I and IGF-II mRNA were also detected during cleavage, gastrulation, and organogenesis, at hatching, during yolk absorption, and at feeding. IGF-IEa-1 and Ea-3 mRNA were detected in unfertilized eggs, while IGF-I Ea-4 was first detected at stage 9 when the zygotic genome is believed to become activated in rainbow trout. IGF-IEa-2 was not detected at any stage of embryonic development. IGF mRNA of immunoreactive peptides have been detected durin embryonic development in all vertebrates studied to date. Our results confirm the presence of IGF-I mRNA in teleost embryos. In addition, IGF-II mRNA is also present in teleost embryos. Our results suggest that the role IGF-I and IGF-II play during embryonic development may be conserved in vertebrates.

Animals↗
PubMed1979

Electron microscope histochemistry of acetylcholinesterase distribution in the optic tectum of teleosts.

An ultrastructural analysis was made on acetylcholinesterase (AChE) localization in the optic tectum of two teleosts, the goldfish and the catfish. Electron microscope histochemistry reveals several details on synthesis, distribution and possible sites of utilization of the enzyme in the different tectal layers. The results show that AChE is synthesized by all the neuronal types present in the optic tectum. The final localization of the enzyme is the result of its synthesis in cell bodies, its storage and transport along dendrites and its release in extracellular spaces. The differences in AChE localization between the two teleosts examined mainly derive from differential enzyme release in the corresponding layers of the optic tectum. Cholinergic synapses cannot be precisely identified by means of AChE histochemistry, but the layers in which maximum release of enzyme in the extracellular spaces occurs most likely correspond to areas where cholinergic mechanisms are operating. In this connection some interesting differences of AChE localization in the superficial tectal layers (stratum marginale, stratum opticum and stratum fibrosum et griseum superficiale) are discussed. Electron microscopic histochemistry of AChE confirms its usefulness in better understanding some links between the anatomical and functional organization of complex neural structures.

Acetylcholinesterase↗
PubMed1996

Distribution of omega-Conotoxin GVIA binding sites in teleost cerebellar and electrosensory neurons.

The distribution of omega-Conotoxin GVIA (CgTx) binding sites was used to localize putative N-type Ca2+ channels in an electrosensory cerebellar lobule, the eminentia granularis pars posterior, and in the electrosensory lateral line lobe of a gymnotiform teleost (Apteronotus leptorhynchus). The binding sites for CgTx revealed by an anti-CgTx antibody had a consistent distribution on somatic and dendritic membranes of specific cell types in both structures. The distribution of CgTx binding was unaffected by co-incubation with nifedipine or AgaToxin IVA, blocking agents for L- and P-type Ca2+ channels, respectively. Incubation with CgTx in the presence of varying levels of extracellular Ca2+ altered the number but not the cell types exhibiting immunolabel. A punctate immunolabel was detected on somatic membranes of granule and stellate cell interneurons in both the eminentia granularis pars posterior and the electrosensory lateral line lobe. Punctate CgTx binding sites were also present on spherical cell somata and on the large presynaptic terminals of primary afferents that terminate on spherical cells in the electrosensory lateral line lobe. No label was detected in association with distal dendritic membranes of any cell class, or with parallel fibers in the respective molecular layers. Binding sites for CgTx in the eminentia granularis are consistent with the established role for N-type Ca2+ channels in cell migrations, an activity which is known to persist in this layer in adult Apteronotus. The distribution of labeled stellate cells with respect to topographic maps in the electrosensory lateral line lobe further suggest that N-type Ca2+ channels are expressed in relation to functional activity across these sensory maps.

Animals↗
PubMed1997

Distribution of S100 immunoreactivity in the retina and optic nerve head of the teleost Tinca tinca L.

The distribution of S100 immunoreactivity within the normal and regenerating retina and optic nerve head of the teleost Tinca tinca L. has been investigated using the avidin-biotin complex (ABC) method and a polyclonal antibody against S100. Astrocytes and Müller cells were labeled with this antibody. This represents the first description of astrocytes localized in the optic nerve head and in the nerve fiber layer of the fish retina displaying a typical bipolar morphology. Horizontal cells in the inner nuclear layer were immunolabeled; we also observed species-specific S100 labeling of horizontal cells of the H1 subtype. No significant changes were seen in the S100 immunoreactive Müller cells, astrocytes, or horizontal cells in the tench retina after optic nerve crushing and during regeneration. These results might help to understand the function of glial cells in the normal and experimentally induced regenerating fish visual system.

Animals↗
PubMed1999

Innervation and control of the adenohypophysis by hypothalamic peptidergic neurons in teleost fishes: EM immunohistochemical evidence.

Previous light microscopic studies have revealed neuropeptide-immunoreactive neurosecretory fibers in the teleostean neurohypophysis, and ultrastructural work has reported direct innervation of endocrine cells by the terminals of fibers penetrating the adenohypophysis. This paper reviews our recent data from ultrastructural, immunohistochemical, receptor localization, and superfusion studies, which suggest a role for neuropeptides in the control of teleost pituitary secretion. We have used a combination of pre- and post-embedding electron microscopic immunolabeling methods to determine which neuropeptides are present in fibers innervating the pituitaries of three species: Poecilia latipinna, Dicentrarchus labrax, and Clarias gariepinus. Numerous axon profiles with immunoreactivity for the neurosecretory peptides vasotocin and isotocin formed large Herring bodies and terminal-like boutons in contact with corticotropic, growth hormone, thyrotropic, and pars intermedia cells. Numerous melanin-concentrating hormone-immunoreactive fibers and scarcer neurotensin and corticotropin-releasing factor-immunoreactive fibers showed similar distributions, terminating close to pars intermedia and corticotropic cells. Somatostatin, cholecystokinin, galanin, substance P, neuropeptide Y, growth hormone-releasing factor, thyrotropin-releasing hormone, and gonadotropin-releasing hormone-immunoreactivities were found in small calibre fibers penetrating among growth hormone, thyrotropic, and gonadotropic cells. These morphological findings have been supplemented by autoradiographic studies, which showed the distribution of binding sites for vasotocin, isotocin, galanin, and neuropeptide Y ligands over specific groups of pituitary cells, and superfusion studies that showed growth hormone release was stimulated by growth hormone-releasing factor and thyrotropin-releasing hormone, but inhibited by somatostatin. The implications of these results for neuropeptidergic control of teleostean pituitary secretions are discussed.

Animals↗
PubMed1999

Intracellular pH regulation in hepatocytes isolated from three teleost species.

The mechanisms of intracellular pH (pH(i)) regulation were studied in hepatocytes isolated from three species of teleost: rainbow trout (Oncorhynchus mykiss), black bullhead (Ameiurus melas) and American eel (Anguilla rostrata). Intracellular pH was monitored over time using the pH-sensitive fluorescent dye BCECF in response to acid loading under control conditions and in different experimental media containing either low Na(+) or Cl(-) concentrations, the Na(+)-H(+) exchanger blocker amiloride or the blocker of the V-type H(+)-ATPase, bafilomycin A(1). In trout and bullhead hepatocytes, recovery to an intracellular acid load occurred principally by way of a Na(+)-dependent amiloride-sensitive Na(+)-H(+) exchanger. In eel hepatocytes, the Na(+)-H(+) exchanger did not contribute to recovery to an acid load though evidence suggests that it is present on the cell membrane and participates in the maintenance of steady-state pH(i). The V-type H(+)-ATPase did not participate in recovery to an acid load in any species. A Cl(-)-HCO(3)(-) exchanger may play a role in recovery to an acid load in eel hepatocytes by switching off and retaining base that would normally be tonically extruded. Thus, it is clear that hepatocytes isolated from the three species are capable of regulating pH(i), principally by way of a Na(+)-H(+) exchanger and a Cl(-)-HCO(3)(-) exchanger, but do not exploit identical mechanisms for pH(i) recovery. J. Exp. Zool. 284:361-367, 1999.

Acid-Base Equilibrium↗