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PubMed2002

Cystic fibrosis transmembrane conductance regulator in teleost fish.

The gills and intestinal epithelia of teleost fish express cystic fibrosis transmembrane conductance regulator (CFTR), and utilize this low conductance anion channel in the apical membrane for ion secretion in seawater gill and in the basolateral membrane for ion absorption in freshwater gill. Similarly, in the intestine CFTR is present in the basolateral membrane for intestinal absorption and also in the apical membrane of secreting intestine. The expression of CFTR and the directed trafficking of the protein to the apical or basolateral membrane is salinity-dependent. The CFTR gene has been cloned and sequenced from several teleost species and although all the major elements in the human gene are present, including two nucleotide binding domains that are common to all ATP binding cassette (ABC) transporters, the sequences are divergent compared to shark or human. In euryhaline fish adapting to seawater, CFTR, localized immunocytochemically, redistributes slowly from a basolateral location to the apical membrane while ion secretory capacity increases. The facility with which teleosts regulate CFTR expression and activation during salinity adaptation make this system an appealing model for the expression and trafficking operation of this labile gene product.

Adaptation, Physiological↗
PubMed1998

Latitudinal differences in species and community richness and in community structure of metazoan endo- and ectoparasites of marine teleost fish.

Relative species diversity of gastrointestinal helminths of 55 teleost fish species did not differ significantly at different latitudes, whereas relative species diversity of metazoan ectoparasites on the heads and gills of 108 teleost fish species showed a significant increase with decreasing latitude and from deep to surface waters. Abundance of endoparasites also was the same at all latitudes, whereas abundance of ectoparasites increased with decreasing latitude and from deep to shallow waters. A comparative analysis using phylogenetically independent contrasts supported these conclusions. Possible reasons for the differences between endo- and ectoparasites are discussed. A detailed analysis of the community structure of gastrointestinal helminths of five Antarctic and three tropical teleosts and of metazoan ectoparasites on the heads and gills of five Antarctic and seven tropical fish species showed the following: abundance and prevalence of infection of endoparasites are similar in Antarctic and tropical fish, but are much greater for tropical than for Antarctic ectoparasites. Relative species diversity of endoparasites is similar for Antarctic and tropical endoparasites, but much greater for tropical than Antarctic ectoparasites. In both Antarctic and tropical fish, different fish of the same species may have different dominant species of endo- and ectoparasites, although there is a greater range of dominant species of tropical ectoparasites, a consequence of the greater species pool available. The most dominant parasite (irrespective of species) represented 80-99% of all endoparasites of Antarctic, and about 50-80% of all endoparasites of tropical fish. The most dominant parasites (irrespective of species) represented about 90-100% of all ectoparasites of Antarctic, and about 20-70% of all ectoparasites of tropical fish, the difference a consequence of the greater species pool of tropical ectoparasites available. The data suggest that both endo- and ectoparasites live in assemblages not structured by interspecific competition.

Animals↗
PubMed1983

Lipovitellin-phosvitin crystals with orthorhombic features: thin-section electron microscopy, gel electrophoresis, and microanalysis in teleost and amphibian yolk platelets and a comparison with other vertebrates.

Yolk-platelet crystals in the teleosts Pelvicachromis pulcher and Noemacheilus barbatulus and the amphibians Xenopus laevis, Rana temporaria, R. esculenta, and Triturus sp. have been studied by electron diffraction and imaging using a standardized processing (glutaraldehyde-osmium tetroxide fixation, glutaraldehyde-urea embedding, thin-section staining), by X-ray microanalysis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of their constituents. The crystal lattice is orthorhombic having--following standardized processing--in three amphibians a = 9.0 nm, b = 17.6 nm, c = 19.2 nm, and in the two teleosts a = 8.9 nm, b = 17.6 nm, c = 20.0 nm (averages). These values are very close to X-ray data from wet crystals (Xenopus laevis). Crystal images in the three axial projections point to the presence of space group P212121 (or an approximation of it since the lipovitellin dimers cannot be fully equivalent in some cases), to differences between the phosvitins of the two teleosts, and to a highly unusual stain exclusion from large crystal constituents interpreted as representing lipovitellin dimers. Microanalysis in ultrathin cryosections and other preparations revealed K and Cl to be the prominent ions in the crystals (and in the superficial layer of the platelet). Gel electrophoresis (including data of cyclostomes) showed considerable molecular variations despite a closely similar crystal architecture, emphasizing a physiological significance of the architecture, which may have remained conserved for nearly 400 million years according to paleontologic views.

Amphibians↗
PubMed1995

Ultrastructural study of osmolality effect on spermatozoa of three marine teleosts.

With particular emphasis on mitochondria that may provide endogenous energy for spermatozoan motility, the morphological changes of the spermatozoa of three marine teleosts, black porgy (Acanthopagrus schlegelli), black grouper (Epinephelus malabaricus), and Atlantic croaker (Micropogonias undulatus), were compared either after activation in artificial sea water or when immersed in various osmotic pressure media. The midpieces of these three teleosts spermatozoa are composed of mitochondria surrounding the flagellum. Each mitochondrion is enclosed by distinct outer and inner membranes. The inner membrane separates the organelle's volume into two phases: the matrix and the intermembrane space. The inner membrane displays numerous infolding cristae that vary in number and shape and extend into the matrix. Following activation with artificial sea water, spermatozoa became motile and both the size and number of mitochondria decrease and then totally disappear. The present study strongly suggests that an energy source(s), responsible for motility, is located within the mitochondria in the midpiece of these three marine teleost spermatozoa.

Animals↗
PubMed2003

Stem cells in the teleost retina: persistent neurogenesis and injury-induced regeneration.

The retina of the adult teleost fish is an important model for studying persistent and injury-induced neurogenesis in the vertebrate central nervous system. All neurons, with the exception of rod photoreceptors, are continually appended to the extant retina from an annulus of progenitors at the margin. Rod photoreceptors, in contrast, are added to differentiated retina only from a lineage of progenitors dedicated to making rods. Further, when the retina is lesioned, the lineage that produces only rods ceases this activity and regenerates retinal neurons of all types. The progenitors that supply neurons at the retinal margin and rod photoreceptors and regenerated neurons in the mature tissue originate from multipotent stem cells. Recent data suggest that the growth-associated neurogenic activity in the retina is regulated as part of the growth hormone/insulin-like growth factor-I axis. This paper reviews recent evidence for the presence of stem cells in the teleost retina and the molecular regulation of neurogenesis and presents a consensus cellular model that describes persistent and injury-induced neurogenesis in the retinas of teleost fish.

Animals↗
PubMed1999

Antigen receptor-mediated activation of extracellular related kinase (ERK) in B lymphocytes of teleost fishes.

In mammalian B lymphocytes, engagement of the B cell antigen receptor (BCR) activates several parallel intracellular signaling pathways which ultimately lead to expression of differentiated functions such as cell proliferation and antibody production or to cellular apoptosis. BCR engagement stimulates the classical mitogen activated protein kinase (MAPK) pathway, also called the extracellular-related kinase (ERK) pathway, resulting in activation of the signature terminal enzyme in the pathway, MAPK (or ERK). BCR signaling also activates the phosphatidyl inositol pathway and its key enzyme protein kinase C (PKC). To investigate the ERK pathway in cells of the teleost immune system, peripheral blood leukocytes from red drum or channel catfish were treated with PKC activators or antibodies which crosslink the BCR. Proteins were identified in both red drum and catfish B cells that resembled mammalian ERKs in molecular weight and in their possessing a distinctive pTEpY dual phosphorylation site. BCR-mediated activation of these presumptive teleost ERKs depended in part (red drum) or in total (catfish) on PKC. To our knowledge this represents the first report of a functional MAPK kinase pathway in teleost fish.

Animals↗
PubMed2003

Neural mechanisms and behaviors for acoustic communication in teleost fish.

Sound communication is not unique to humans but rather is a trait shared with most non-mammalian vertebrates. A practical way to address questions of vocal signal encoding has been to identify mechanisms in non-mammalian model systems that use acoustic communication signals in their social behavior. Teleost fishes, the largest group of living vertebrates, include both vocal and non-vocal species that exploit a wide range of acoustic niches. Here, we focus on those vocal species where combined behavioral and neurobiological studies have recently begun to elucidate a suite of adaptations for both the production and the perception of acoustic signals essential to their reproductive success and survival. Studies of these model systems show that teleost fish have the vocal-acoustic behaviors and neural systems both necessary and sufficient to solve acoustic problems common to all vertebrates. In particular, behavioral studies demonstrate that temporal features within a call, including pulse duration, rate and number, can all be important to a call's communicative value. Neurobiological studies have begun to show how these features are produced by a vocal motor system extending from forebrain to hindbrain levels and are encoded by peripheral and central auditory neurons. The abundance and variety of vocal fish present unique opportunities for parallel investigations of neural encoding, perception, and communication across a diversity of natural, acoustic habitats. As such, investigations in teleosts contribute to our delineating the evolution of the vocal and auditory systems of both non-mammalian and mammalian species, including humans.

Animal Communication↗
PubMed2000

Topography and topology of the teleost telencephalon: a paradox resolved.

Analysis of vasculature in the telencephalic pallium of a teleost allows the considerable depth of the sulcus externus, which lies at the lateral extent of the ependymal attachment, to be appreciated. The depth of this sulcus is compelling evidence for a simple eversion process (an outfolding of the pallial wall of each hemisphere) during telencephalic development in all ray-finned fishes that is not complicated in teleosts by secondary migration of pallial cell groups. A simple eversion process is known to occur in some ray-finned fishes with relatively simple telencephalic cytoarchitecture but has been disputed in teleosts based on the pattern of olfactory tract projections. A resolution to the conflicting hypotheses of pallial relationships across ray-finned fishes and in comparison with other craniate radiations is presented here, based on a re-examination of hodological and histochemical data mandated by this sulcal anatomy.

Animals↗
PubMed2000

Lesions do not provoke GFAP-expression in the GFAP-immunonegative areas of the teleost brain.

In the mammalian and avian brains the predominant astroglial elements are astrocytes, and the distribution of GFAP-immunopositivity is rather uneven, some large brain areas being almost devoid of GFAP-immunopositivity. In these areas however, an intense GFAP-immunopositivity appears following injury. In the teleost brain most of the areas are GFAP-immunopositive and ependymoglia predominates. However, a large area, the layer of the sensory neurons in the vagal lobe, is devoid of GFAP. The question arises, whether the lack of GFAP-immunopositivity in the teleost brain is also due to the repression of the GFAP-production, as in birds and mammals, or due to the lack of cells capable of expressing GFAP. To answer this question, stab wounds were made in the vagal lobe of goldfish, as well as in the tectum, in which moderately dense but highly organized GFAP-immunopositive glia has been detected in intact animals. In the layer of the sensory neurons in the vagal lobe no GFAP-immunopositivity appeared even after lesions had been introduced. In the tectum, a rather slight increase of the intensity of the immunostaining was observed in the glial fibers near the lesions but no typical reactive glia similar to that found in mammals or birds, was observed. The results suggest that a lesion does not provoke GFAP-expression in GFAP-immunonegative brain areas in teleosts, in contrast to what is observed in mammals and birds.

Animals↗
PubMed2001

Glucose intolerance in teleost fish: fact or fiction?

Teleost fish are generally considered to be glucose intolerant. This mini-review examines some of the background and the possible mechanistic bases for this statement. Glucose intolerance is a clinical mammalian term meaning that a glucose load results in persistent hyperglycemia. Teleost fish show persistent hyperglycemia that is generally coincident with transient hyperinsulinemia. The fact that teleost generally have high plasma insulin compared with mammals implies insulin-deficiency is not a suitable explanation for this persistent hyperglycemia. Instead, peripheral utilization of glucose is probably the principle cause of hyperglycemia. Recent evidence for muscle insulin receptors, glucose transporters and hexokinase/glucokinase is reviewed and future experimental directions are suggested. If by altering peripheral glucose utilization fish could become more glucose tolerant, costs to the aquaculture industry may be substantially reduced.

Animals↗
PubMed2003

Matrix Gla protein gene expression and protein accumulation colocalize with cartilage distribution during development of the teleost fish Sparus aurata.

Matrix Gla protein (MGP) is a member of the family of extracellular mineral-binding Gla proteins, expressed in several tissues with high accumulation in bone and cartilage. Although the precise molecular mechanism of action of this protein remains unknown, all available evidence indicates that MGP plays a role as an inhibitor of mineralization. We investigated the sites of gene expression and protein accumulation of MGP throughout development of the bony fish Sparus aurata, by in situ hybridization, Northern and RT-PCR Southern hybridization, and immunohistochemistry. The results obtained were compared with the patterns of developmental appearance of cartilaginous and mineralized structures in this species, identified by histological techniques and by detection of mRNA presence and protein accumulation of osteocalcin (Bone Gla protein), a marker for osteoblasts known to accumulate in bone mineralized extracellular matrix. The expression of MGP mRNA was first detected at 2 days posthatching (dph) by Northern analysis, RT-PCR amplification, and in situ hybridization, and thereafter continuously detected at various levels of intensity, until 130 dph. In situ hybridization analysis performed in parallel with immunohistochemistry indicated that until ca. 45 dph, the MGP gene was highly expressed in a number of different tissues including skull, jaw, neural and hemal arches, and heart and the protein accumulated in cartilaginous tissues. At 85 dph, a stage when most skeletal structures are mineralized, MGP gene expression and protein accumulation were restricted to the remaining cartilaginous structures, whereas osteocalcin gene expression and protein accumulation were localized in most mineralized structures. MGP gene expression was also detected in heart and kidney, although in situ hybridization only detected MGP mRNA in heart, located in the arterial bulbus and not in the cardiac muscle. Our results are in agreement with those recently described for MGP localization in adult tissues of another teleost fish, as well as available data from higher vertebrates, strengthening the hypothesis of a conserved function for MGP from teleost fish to human, a period of more than 200 million years of evolution. In addition, Sparus aurata, a marine teleost fish routinely grown in captivity, appears to be a good model to further analyze MGP gene expression and regulation.

Amino Acid Sequence↗
PubMed2000

Methods for cell cycle analysis and detection of apoptosis of teleost cells.

Flow cytometric techniques have not been previously used on a routine basis to study teleost cell growth and development. In the present chapter, flow instrumentation and cell preparation protocols are given in order to provide evaluation criteria characteristic of different phases of the cell cycle. Flow cytometry is used as an analytical and diagnostic tool to measure DNA ploidy as well as to measure alterations in cell cycle profiles characteristic of random DNA fragmentation (necrosis) compared to patterned DNA cleavage (apoptosis). The types of information obtained by flow analysis include the visualization of cell subpopulations with differing DNA content. For each identified nuclei subpopulation, the parameters of population size, fractions of nuclei in each phase of the cell cycle and computation of DNA ratios can be discerned. Data are presented of ex vivo prepared teleost nonspecific cytotoxic cells (NCC) at resting phase compared to NCC undergoing DNA hypoploid changes characteristic of apoptosis. These cells are compared with a teleost tissue cultured cell line maintained under optimum cell growth conditions versus cells undergoing necrotic cellular pathology. Finally, the requirements for optimum flow analysis are described. Techniques including gating strategies, voltage and gain settings, discrimination options and data collection and interpretation are provided.

Animals↗
PubMed1995

Identification of cytochrome P-450 1A (CYP1A) genes from two teleost fish, toadfish (Opsanus tau) and scup (Stenotomus chrysops), and phylogenetic analysis of CYP1A genes.

Cytochrome P-450-mediated responses to environmental challenges are well known in diverse animal taxa, but the evolution of the complex gene superfamily coding for these enzymes is poorly understood. Here we report a phylogenetic analysis of the cytochrome P-450 1A (CYP1A) genes including two new sequences determined from teleost fish, toadfish (Opsanus tau) and scup (Stenotomus chrysops). Degenerate PCR primers were used to amplify a 1.2 kbp fragment from liver cDNA. The toadfish PCR product was used as a probe to identify a full-length CYP1A clone from a toadfish liver cDNA library. The entire coding region of the scup CYP1A was obtained by rapid amplification of cDNA ends (RACE) using specific primers based on the sequence of the partial PCR product. The predicted protein sequences for toadfish and scup CYP1A shared 78% and 83% amino acid identity with rainbow trout CYP1A1 respectively. Amino acid identity with mammalian CYP1A proteins ranged from 51 to 60% for 505 aligned positions. Phylogenetic analysis of four teleost fish CYP1A genes (trout, toadfish, scup and plaice) and 12 mammalian CYP1A genes suggests a monophyletic origin of the teleost genes, with the trout gene being most divergent, and indicates three distinct groupings: mammalian 1A1, mammalian 1A2, and fish 1A. This supports the idea that the gene duplication event which gave rise to CYP1A1 and CYP1A2 occurred after the divergence of the lines leading to mammals and fish. These results establish a molecular phylogeny within the CYP1A subfamily, the first such detailed phylogenetic analysis within a cytochrome P-450 family.

Amino Acid Sequence↗
PubMed1998

Two distinct types of fatty acid-binding protein are expressed in heart ventricle of Antarctic teleost fishes.

This report provides the first evidence for the existence of two distinct types of fatty acid-binding protein (FABP) in cardiac tissue of vertebrates. Four species of Antarctic teleost fish (Chaenocephalus aceratus, Cryodraco antarcticus, Gobionotothen gibberifrons and Notothenia coriiceps) exhibited two FABP mRNAs of 1. 0 kb and 0.8 kb, which we have termed Hh-FABP and Had-FABP (isolated from Heart tissue, with similarity to mammalian heart-type FABP or mammalian adipose-type FABP respectively). These FABP types appear to be products of distinct genes. Both FABP transcripts were abundant in cardiac and aerobic pectoral muscle. However, relative abundance of the two types varied distinctly among other tissues such as kidney, brain, spleen and white muscle. Neither FABP type was expressed in liver or intestine. The coding regions of Hh-FABP and Had-FABP cDNAs from the same species are only approximately 60% identical with one another. However, homologues of each FABP species, which exhibit >98% identity to their respective types, were isolated from three other Antarctic teleosts. Phylogenetic analysis of aligned amino-acid sequences places Hh-FABP with other vertebrate heart-type FABPs, and Had with adipose/cutaneous FABPs. Expression of two distinct FABPs in cardiac tissue of Antarctic teleosts may be related to their ability to both utilize fatty acid as the primary metabolic fuel and to store lipid intracellularly.

Amino Acid Sequence↗
PubMed2024

Teleost Hox code defines regional identities competent for the formation of dorsal and anal fins.

The dorsal and anal fins can vary widely in position and length along the anterior-posterior axis in teleost fishes. However, the molecular mechanisms underlying the diversification of these fins remain unknown. Here, we used genetic approaches in zebrafish and medaka, in which the relative positions of the dorsal and anal fins are opposite, to demonstrate the crucial role of hox genes in the patterning of the teleost posterior body, including the dorsal and anal fins. By the CRISPR-Cas9-induced frameshift mutations and positional cloning of spontaneous dorsalfinless medaka, we show that various hox mutants exhibit the absence of dorsal or anal fins, or a stepwise posterior extension of these fins, with vertebral abnormalities. Our results indicate that multiple hox genes, primarily from hoxc-related clusters, encompass the regions responsible for the dorsal and anal fin formation along the anterior-posterior axis. These results further suggest that shifts in the anterior boundaries of hox expression which vary among fish species, lead to diversification in the position and size of the dorsal and anal fins, similar to how modulations in Hox expression can alter the number of anatomically distinct vertebrae in tetrapods. Furthermore, we show that hox genes responsible for dorsal fin formation are different between zebrafish and medaka. Our results suggest that a novel mechanism has occurred during teleost evolution, in which the gene network responsible for fin formation might have switched to the regulation downstream of other hox genes, leading to the remarkable diversity in the dorsal fin position.

Animals↗
PubMed1990

Complete nucleotide sequence of an immunoglobulin heavy-chain gene and analysis of immunoglobulin gene organization in a primitive teleost species.

The immunoglobulin heavy-chain variable region (VH) locus in a phylogenetically primitive teleost (Elops saurus) has been characterized by a strategy that relied initially on cross-hybridization between genomic VH segments and a murine VH probe. Using a homologous (Elops) VH probe and DNA sequencing, this gene family has been shown to be complex and to contain overt pseudogenes. A homologous probe also has been used to isolate a full copy length cDNA containing constant (CH) as well as joining (JH) and VH regions. Genomic analyses using CH-, JH-, and VH-specific probes have demonstrated the presence of only a single hybridizing CH and several JH elements. JH-CH linkage is less than or equal to 3.6 kilobases (kb) and VH-CH linkage is less than or equal to 100 kb, as estimated by field-inversion gel electrophoresis. An additional VH family sharing less than 50% nucleotide identity with the prototype Elops VH sequence is described. Taken together, these results suggest that the immunoglobulin VH locus in a comparatively primitive teleost resembles the VH locus in mammals, but not that found in the more phylogenetically distant elasmobranchs. The evolutionary radiations of cartilaginous and bony fishes are associated with a dramatic change in the organization and, presumably, regulation of immunoglobulin genes. The origins of the modern VH gene locus can be traced to the primitive teleost fishes.

Amino Acid Sequence↗
PubMed1993

Sequence analysis of teleost retina-specific lactate dehydrogenase C: evolutionary implications for the vertebrate lactate dehydrogenase gene family.

At least two gene duplication events have led to the three lactate dehydrogenase (LDH; EC 1.1.1.27) isozymes (LDH-A, LDH-B, and LDH-C) of chordates. The prevailing model for the evolution of the LDH loci involves duplication of a primordial LDH locus near the origin of vertebrates, giving rise to Ldh-A and Ldh-B. A third locus, designated Ldh-C, is expressed in the spermatocytes of mammals and a single family of birds and in the eye or liver tissues of teleost fishes. Ldh-C might have arisen independently in these taxa as duplications of either Ldh-A or Ldh-B. Several authors have challenged this traditional hypothesis on the basis of amino acid sequence and immunological similarity of the three LDH isozymes. They suggest that the primordial LDH gene was duplicated to form Ldh-C and a locus that later gave rise to Ldh-A and Ldh-B. We have differentiated between these hypotheses by determining the cDNA sequence of the retina-specific LDH-C from a teleost, Fundulus heteroclitus. On the basis of amino acid sequence similarity, we conclude that the LDH-C isozymes in fish and mammals are not orthologous but derive from independent gene duplications. Furthermore, our phylogenetic analyses support previous hypotheses that teleost Ldh-C is derived from a duplication of the Ldh-B locus.

Amino Acid Sequence↗
PubMed2000

Identification of a third distinct estrogen receptor and reclassification of estrogen receptors in teleosts.

This paper describes three distinct estrogen receptor (ER) subtypes: ERalpha, ERbeta, and a unique type, ERgamma, cloned from a teleost fish, the Atlantic croaker Micropogonias undulatus; the first identification of a third type of classical ER in vertebrate species. Phylogenetic analysis shows that ERgamma arose through gene duplication from ERbeta early in the teleost lineage and indicates that ERgamma is present in other teleosts, although it has not been recognized as such. The Atlantic croaker ERgamma shows amino acid differences in regions important for ligand binding and receptor activation that are conserved in all other ERgammas. The three ER subtypes are genetically distinct and have different distribution patterns in Atlantic croaker tissues. In addition, ERbeta and ERgamma fusion proteins can each bind estradiol-17beta with high affinity. The presence of three functional ERs in one species expands the role of ER multiplicity in estrogen signaling systems and provides a unique opportunity to investigate the dynamics and mechanisms of ER evolution.

Amino Acid Sequence↗