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At least 19 recordsLinked to original sources
PubMed2006

Cloning of stanniocalcin (STC) cDNAs of divergent teleost species: Monomeric STC supports monophyly of the ancient teleosts, the osteoglossomorphs.

Molecular cloning of teleost stanniocalcin (STC) cDNAs was undertaken in two species of order Osteoglossiformes of subdivision Osteoglossomorpha and one species of each of orders Cypriniformes and Perciformes within the subdivision Euteleostei. The elephantnose (Gnathonemus petersii) and the butterflyfish (Pantadon buchholzi) are basal teleosts in different osteoglossiforme suborders yet their 218 amino acid (aa) mature hormones, from prehormones of 249 and 251aa, respectively, have only 10 cysteine residues. A substitution for cysteine at the intermonomeric disulfide linkage site, implies that their STCs exist as monomeric peptides, as is the case with STC from another osteoglossormorph, arawana [Amemiya, Y., Marra, L.E., Reyhani, N., Youson, J.H., 2002. Stanniocalcin from an ancient teleost: a monomeric form of the hormone and a possible extracorpuscular distribution. Mol. Cell. Endocrinol. 188, 141-150]. The STC cDNA of the generalized teleost and cyprinid, the white sucker (Catostomus commersoni), encodes a prehormone of 249aa with a signal peptide of 31aa and a mature protein of 218aa that possesses 11 cysteine residues. The latter feature is consistent with a previous analysis that white sucker mature STC is a glycosylated, homodimeric peptide [Amemiya, Y., Marra, L.E., Reyhani, N., Youson, J.H., 2002. Stanniocalcin from an ancient teleost: a monomeric form of the hormone and a possible extracorpuscular distribution. Mol. Cell. Endocrinol. 188, 141-150]. An open reading frame of the STC cDNA of the derived teleost and perciforme, the smallmouth bass (Micropterus dolomieui), encodes a prehormone of 255aa with a signal peptide of 33aa and a mature protein of 222aa. The position of the 11 cysteines in smallmouth bass STC suggests that it exists as a homodimeric peptide. A phylogenetic analysis, using the new STC-1 amino acid sequences and those in the gene data base provided strong support for monophyly of the Osteoglossomorpha and indicated, with positioning of white sucker and smallmouth bass, that this molecule has some utility as a taxonomic marker. This analysis also suggested that two STC-1 gene sequences exist in multiple fish genomes, and that they may be a product of the fish-specific genome duplication. The mutation in the osteoglossomorph STC likely occurred after the appearance of the first teleosts and before movement of the tectonic plates.

Amino Acid Sequence↗
PubMed2001

Gonadotropin-releasing hormones (GnRHs) in a primitive teleost, the arowana: phylogenetic evidence that three paralogous lineages of GnRH occurred prior to the emergence of teleosts.

Multiple molecular forms of gonadotropin-releasing hormone (GnRH) are present in a single vertebrate species. To extend the knowledge on GnRH evolution and the number of GnRH forms in one organism, GnRH cDNAs have been isolated and characterized from one of the most primitive teleosts, the arowana Scleropages jardini. This species had two molecular forms of GnRH: salmon-type GnRH (sGnRH) and chicken-II-type GnRH (cGnRH-II). Sequence comparison between the prepro-GnRHs of the arowana and those of other teleosts indicated that sGnRH represented a paralogue separate from any other forms of GnRH. Consistently, subsequent phylogenetic analysis showed that known forms of GnRH in teleosts fell into three paralogous lineages: sGnRH alone on one lineage, cGnRH-II on another, and many other forms on the other. These results suggest that an ancestral GnRH gene duplicated twice prior to the emergence of teleosts and, therefore, that teleosts, and probably also tetrapods, would possess three paralogous forms of GnRH in individual brains.

Amino Acid Sequence↗
PubMed2003

Structure and evolution of the teleost extraretinal rod-like opsin (errlo) and ocular rod opsin (rho) genes: is teleost rho a retrogene?

In Teleost fish examined to date the ocular rod opsin gene, rho, is intronless, unlike the rod opsin genes of other vertebrate classes which possess a five exon/four intron structure. We have examined in silico the structure of rho (which is expressed uniquely in the retina) and the closely related extraretinal rod-like opsin (exo-rhodopsin) gene, errlo (which is expressed uniquely in the pineal), in the puffer-fish, Fugu rubripes (Takifugu rubripes). Whilst the ocular rho is intronless in common with other Teleosts, the pineal errlo has the five exon/four intron structure common to the rod opsin gene of other vertebraes. A comparison of the sequence surrounding the errlo and rho loci indicates that the errlo locus is syntenic with RHO, the human rod opsin gene, rather than rho. We suggest that the intronless rho may have arisen through an ancient retrotransposition of a mature mRNA originating from errlo. This duplication event has occurred early in the evolution of the Actinopterygii (ray-finned fish) since the rho of the primitive Actinopterygians such as sturgeon, bowfin, and gar is also intronless. Since it appears that the intron containing errlo is the ancestral opsin gene that gave rise to the intronless rho in the Teleostei, errlo is therefore the true orthologue of the rod opsin gene in other vertebrate classes. We suggest that loss of expression of errlo in the retina could be related to the metabolic and physiological advantages, such as a reduction in splicing events during RNA processing, that may be conferred through possession of an additional, intronless rod opsin gene in the form of rho.

Animals↗
PubMed1991

Ureogenesis in a freshwater teleost: an unusual sub-cellular localization of ornithine-urea cycle enzymes in the freshwater air-breathing teleost Heteropneustes fossilis.

Sub-cellular localization of different ornithine-urea cycle enzymes was studied in the liver and kidney of a freshwater air-breathing teleost. Carbamyl phosphate synthetase, ornithine transcarbamylase, and arginase were found to be localized inside the mitochondria, and argininosuccinate synthetase and argininosuccinate lyase were found in the soluble fraction. Mitochondrial localization of arginase, a feature known in marine elasmobranchs and toadfishes, indicates the evolutionary position of H. fossilis to be different from that of present day freshwater teleosts.

Animals↗
PubMed1986

Responses to reversed NH3 and NH4+ gradients in a teleost (Ictalurus punctatus), an elasmobranch (Raja erinacea), and a crustacean (Callinectes sapidus):evidence for NH4+/H+ exchange in the teleost and the elasmobranch.

Ammonia excretion rates of channel catfish, Ictalurus punctatus, little skate (Raja erinacea), and blue crab (Callinectes sapidus) were measured in experimental regimes which permitted simultaneous assessment of the partial pressure gradients for nonionized NH3 and the chemical concentration gradients of NH4+. Under conditions of low external ammonia, the average ammonia excretion was +295 microM kg-1 h-1 for catfish, +149 microM kg-1 h-1 for blue crabs, and +59 microM kg-1 h1 for skates with partial pressure gradients of +72.5 mu Torr, +413 mu Torr, and +24.4 mu Torr, respectively; and [NH4+] gradients of +189 microM l-1, +643 microM l-1, and +107 microM l-1 (positive indicating greater from inside to medium). When the external ammonia was increased to 1.15 mM l-1, both gradients were reversed, and the net ammonia movement was initially from the external water into all three species. In the catfish the inward movement ceased, however, and ammonia excretion eventually resumed in the face of reversed gradients of both NH3 partial pressure and [NH4+]. Unidirectional Na+ influx, indicative of a Na+/NH4+ exchange, did not increase. The ammonia data, changes in titratable acidity, and net apparent H+ efflux were all consistent with a linked extrusion of internal NH4+ for external H+. Incorporation of such an exchange into a computer simulation model of the ammonia equilibrium and exchange system duplicated the experimental data. Other hypotheses failed to match experimental data, or failed to predict internal ammonia levels lower than outside. In the crab, internal ammonia levels rose rapidly to concentrations and partial pressures above the external medium until excretion was reestablished, with no evidence of maintenance of a reversed gradient. In the skate, internal concentrations rose appreciably in the first hour and continued to rise for 6-8 h, with no resumption of ammonia excretion. The interspecies differences appear to be due at least partly to differences in ammonia permeability of the gills.

Ammonia↗
PubMed1989

Polyunsaturated fatty acid metabolism in fish cells: differential metabolism of (n-3) and (n-6) series acids by cultured cells originating from a freshwater teleost fish and from a marine teleost fish.

1. The incorporation and metabolism of (n-3) and (n-6) polyunsaturated fatty acids (PUFA) supplemented to growing cultures were studied in rainbow trout (RTG-2) and turbot (TF) cell lines. 2. A fatty acid concentration of 20 microM considerably altered the fatty acid composition of the cells without affecting lipid class composition or the appearance of cytoplasmic lipid droplets. 3. Both cell lines exhibited considerable delta 6 desaturase activities. 4. Whereas delta 5 desaturase activity was expressed in RTG-2 cells, delta 4 desaturase activity was absent and, conversely, delta 4 desaturase activity was expressed in TF cells, but there was an apparent deficiency in the C18 to C20 elongase multi-enzyme complex. 5. The delta 6 desaturase activity in both cell lines showed little preference between 18:2(n-6) and 18:3(n-3) but the delta 5 desaturase activity of RTG-2 cells and the delta 4 desaturase activity of TF cells showed a preference for (n-3)PUFA. 6. Two fish oil concentrates were assessed for their ability to generate fatty acid compositions in the cell lines more closely resembling those of intact fish tissues.

Animals↗
PubMed2000

Suppression of osteoclastic activities by calcitonin in the scales of goldfish (freshwater teleost) and nibbler fish (seawater teleost).

Using a tartrate-resistant acid phosphatase (TRACP) activity, the effects of calcitonin (CT) and estradiol-17beta(E(2)) on osteoclastic activities in cultured scales of goldfish (freshwater fish) and nibbler fish (seawater fish) were examined. In mature male and female goldfish, scales were collected and incubated in Earle's minimun essential medium (MEM) supplemented with either CT (100 ng/ml) or E(2) (100 ng/ml). In both sexes, CT suppressed TRACP activities in the scales, whereas E(2) increased them. When CT (100 ng/ml) and E(2) (100 ng/ml) were added simultaneously to MEM, TRACP activities in the scales did not change as compared with the control. Similar results were obtained with the scales of female nibbler fish. In goldfish, furthermore, the activation of scale TRACP by E(2) was suppressed, depending on CT concentrations (100 pg/ml to 1 microg/ml). In fish reproduction, this function of CT may be useful to protect scales from excess degradation of calcium at vitellogenesis.

Acid Phosphatase↗
PubMed2025

Multiple Horizontal Transfers of Immune Genes Between Distantly Related Teleost Fishes.

Horizontal gene transfer (HGT) is less frequent in eukaryotes than in prokaryotes, yet can have strong functional implications and was proposed as a causal factor for major adaptations in several eukaryotic lineages. Most cases of eukaryote HGT reported to date are inter-domain transfers, and few studies have investigated eukaryote-to-eukaryote HGTs. Here, we performed a large-scale survey of HGT among 242 species of ray-finned fishes. We found multiple lines of evidence supporting 19 teleost-to-teleost HGT events that involve 17 different genes in 11 teleost fish orders. The genes involved in these transfers show lower synonymous divergence than expected under vertical transmission, their phylogeny is inconsistent with that of teleost fishes, and they occur at non-syntenic positions in donor and recipient lineages. The distribution of HGT events in the teleost tree is heterogenous, with 8 of the 19 transfers occurring between the same two orders (Osmeriformes and Clupeiformes). Though we favor a scenario involving multiple HGT events, future work should evaluate whether hybridization between species belonging to different teleost orders may generate HGT-like patterns. Besides the previously reported transfer of an antifreeze protein, most transferred genes play roles in immunity or are pore-forming proteins, suggesting that such genes may be more likely than others to confer a strong selective advantage to the recipient species. Overall, our work shows that teleost-to-teleost HGT has occurred on multiple occasions, and it will be worth further quantifying these transfers and evaluating their impact on teleost evolution as more genomes are sequenced.

Animals↗
PubMed1999

Duality of gonadotropin in a primitive teleost, Japanese eel (Anguilla japonica).

The duality of gonadotropin (GTH) is well-established in relatively modern teleosts. In primitive teleosts such as eel and catfish, however, only a single GTH (GTH-II) has been isolated and characterized. Therefore, the objective of this study was to clarify the duality of GTH, particularly the presence of GTH-I in primitive teleosts. We attempted to obtain a cDNA encoding the beta subunit of GTH-I from Japanese eel, Anguilla japonica, as a representative primitive teleost species. Rapid amplification of cDNA ends (RACE) polymerase chain reaction (PCR) was used to amplify GTH-Ibeta cDNA prepared from immature male Japanese eel pituitaries, and the obtained PCR products were subcloned and sequenced. A degenerate PCR primer was designed based on a highly conserved region between teleost GTH-Ibeta and mammalian FSHbeta. DNA sequence analysis of the cloned PCR products confirmed the presence of the predicted complete coding region as well as the 5' and 3' untranslated regions. The deduced amino acid sequence from these clones showed high homology to goldfish GTH-Ibeta (60%), whereas the identity between Japanese eel GTH-Ibeta and GTH-IIbeta was lower (42%). Phylogenetic analysis confirmed that Japanese eel GTH-Ibeta belonged to the teleost GTH-Ibeta group. These results provide a definitive proof of the presence of two types of GTHs (GTH-I and GTH-II) in Japanese eel, as has been shown in other teleosts. The duality of GTHs is applicable for teleosts in general. Northern blot analysis showed the transcripts of Japanese eel GTH-Ibeta and GTH-IIbeta to be 1200 and 750 bases, respectively. GTH-Ibeta gene was expressed in immature fish, while GTH-IIbeta gene was expressed in spermiating males and ovulated females, suggesting that two GTHs are differentially expressed at different sexual stages and may play separate roles in the reproductive process in Japanese eel.

Amino Acid Sequence↗
PubMed2002

Teleost introns are characterized by a high A+T content.

We previously observed that Antarctic fish genes contain intron sequences of high A+T content (60-70% average A+T) which are in stark contrast with adjacent protein coding-sequences. Here, we report that this disparity in intron/exon base composition is a common feature among teleosts. We analyzed 483 teleost genomic DNA sequences, containing 2583 introns, from 80 teleost genera that populate polar, temperate, or tropical habitats. Eighty-nine percent of teleost introns display an A+T content between 50-84% A+T with a mean of 60% A+T. In contrast, only 37% of teleost exons have an A+T content greater-than 50% with a mean of 48% A+T. A comparison to homologous mammalian genes showed a striking difference; in this case, introns and exons have similar base compositions, averaging 45-47% A+T. This indicates that most teleost genes exhibit a large difference in base composition between their introns and exons. There was no correlation of teleost intron A+T content to intron length or habitat temperature range. Thus, teleost intron sequences tend to show the common feature of being much higher in A+T content then neighboring exons.

Adenine↗
PubMed1979

Activities of enzymes of fat and ketone-body metabolism and effects of starvation on blood concentrations of glucose and fat fuels in teleost and elasmobranch fish.

1. Activities of 3-oxo acid CoA-transferase and carnitine palmitoyltransferase together with tri- and di-acylglycerol lipase were present in red and heart muscles of the teleost fish. However, d-3-hydroxybutyrate dehydrogenase activity was not detectable. These results suggest that the heart and red muscles of the teleosts should be able to utilize the fat fuels triacylglycerol, fatty acids or acetoacetate, but not hydroxybutyrate. The muscles from the elasmobranchs differed in that d-3-hydroxybutyrate dehydrogenase and 3-oxo acid CoA-transferase activities were present, but carnitine palmitoyltransferase activity was not detectable. This suggests that ketone bodies are the most important fat fuels in elasmobranchs. 2. The concentrations of acetoacetate, 3-hydroxybutyrate, glycerol, non-esterified fatty acids and triacylglycerols were measured in blood or plasma of several species of fish (teleosts and elasmobranchs) in the fed state. Teleosts have a 10-fold higher concentration of plasma non-esterified fatty acids, but a lower blood concentration of ketone bodies; both acetoacetate and 3-hydroxybutyrate are present in blood of elasmobranchs, whereas 3-hydroxybutyrate is absent from that of the teleosts. 3. The effects of starvation (up to 150 days) on the concentrations of blood metabolites were studied in a teleost (bass) and an elasmobranch (dogfish). In the bass there was a 60% decrease in blood glucose after 100 and 150 days starvation. In dogfish there was a large increase in the concentration of ketone bodies, whereas in bass the concentration of acetoacetate (the only ketone body present) remained low (<0.04mm) throughout the period of starvation. The concentration of plasma non-esterified fatty acids increased in bass, but decreased in dogfish. These changes are consistent with the predictions based on the enzyme-activity data. 4. Starvation did not change the activities of ketone-body-utilizing enzymes or that of phosphoenolpyruvate carboxykinase in heart and red skeletal muscles of both fish, but it decreased markedly the activity of phosphoenolpyruvate carboxykinase in white skeletal muscle of both fish. However, in the liver of the dogfish, starvation resulted in a twofold increase in the activities of 3-hydroxybutyrate dehydrogenase and acetoacetyl-CoA thiolase, whereas in bass liver it decreased the activity of acetoacetyl-CoA thiolase and increased that of 3-oxo acid CoA-transferase. The activity of phosphoenolpyruvate carboxykinase was increased twofold in the liver of bass, but was unchanged in that of the dogfish. 5. The difference in changes in concentrations of blood metabolites and enzyme activities in the two fish support the suggestion that, in starvation, ketone bodies, but not non-esterified fatty acids, are an important fuel for muscle in elasmobranchs, whereas non-esterified fatty acids, but not ketone bodies, are an important fuel in teleosts. The results are discussed in relation to the evolution of a discrete lipid-storing adipose tissue in teleosts and higher vertebrates.

Animals↗
PubMed1982

Control of renal function in freshwater and marine teleosts.

The glomerular filtration rate (GFR) of teleost fishes is highly variable and is influenced by glomerular intermittency, environmental salinity, renal perfusion pressure, and some hormones. In freshwater (FW) teleosts, the primary function of the kidney is to excrete excess water while retaining most of the filtered solutes, and GFR is a major determinant of urine flow. Low permeability to water prevails in the distal nephron of FW teleosts, and the majority of the filtered Na and Cl is reabsorbed without osmotic accompaniment of water. Prolactin appears to regulate osmotic permeability to water. Isolated and perfused distal tubules from FW teleosts revealed a transepithelial voltage (Vt) that was positive in the lumen. Both Na and Cl participate in generating lumen-positive Vt. Marine teleosts, which are exposed to Na loading and dehydration, ingest seawater to compensate for their osmotic water loss, and secrete divalent ions, mainly Mg and SO4, from the kidney. The urine flow of marine teleosts is primarily determined by fluid secretion accompanied by divalent ions and subsequent isosmotic reabsorption with NaCl. Interdependence of Na and Cl transport has been noted in the urinary bladder of marine teleosts. There is presently no known humoral substance that regulates NaCl and divalent ion transport in the teleost kidney.

Animals↗
PubMed2002

Neuronal organization of the melanin-concentrating hormone system in primitive actinopterygians: evolutionary changes leading to teleosts.

Hypothalamic melanin-concentrating hormone (MCH) neurones occur in all vertebrates and have an apparent neuromodulatory role. In teleost fish, however, MCH is used also as a neurohypophysial hormone, controlling skin color, and as a hypophysiotrophic peptide. This work describes the central location of immunoreactive MCH perikarya and their projections to the pituitary in a range of ancestral fish to determine the phylogenetic stage when the peptide adopted these roles. In all actinopterygians examined, including polypteriformes, chondrosteans, holosteans, and teleosts, immunoreactive fibers were abundant in the median eminence or, in the case of teleosts, within the pars distalis itself, suggesting MCH acquired a hypophysial regulatory role early in vertebrate evolution. MCH fibers appeared to be absent from the posterior neurohypophysis of the polypteriform Calamoichthys but were evident in this region in the chondrostean Acipensor, the holosteans Lepisosteus and Amia, and all teleosts, suggesting its use as a neurohypophysial hormone. The ability of MCH to induce skin pallor seems to have arisen at a later stage, probably in the preholosteans. This hormonal role coincides with the migration of MCH perikarya away from the ventricular surface and their enlargement into magnocellular neurones. In the higher teleosts, magnocellular hypothalamo-neurohypophysial neurones predominate in size and number, whereas smaller periventricular MCH neurones associated with the paraventricular organ, that are prominent in lampreys, early actinopterygians and tetrapods, are reduced in teleosts. The data suggest that, in teleost fish, earlier functions of the peptide may have become subordinate to its novel pigmentary role.

Animals↗
PubMed1991

Galanin-like immunoreactivity in the brain of teleosts: distribution and relation to substance P, vasotocin, and isotocin in the Atlantic salmon (Salmo salar).

The presence of galanin-like substances and their relation to substance P-, vasotocin-, and isotocin-immunoreactive neurons and fibers in the brain of teleosts was investigated with immunohistochemical methods. Two specific antisera against synthetic porcine galanin (GAL) revealed cell bodies and fibers in the brain of four different teleost species (Salmo salar, Carassius carassius, Gasterosteus aculeatus, and Anguilla anguilla). In all four species the main location of galanin immunoreactivity was in the hypothalamo-pituitary region. A detailed study of the distribution of galanin immunoreactivity in S. salar showed that galanin immunoreactive (GALir) perikarya were present in the nucleus preopticus periventricularis, an area that may be compared to the supraoptic nucleus in mammals, and in the nucleus lateralis tuberis, a nucleus involved in pituitary control in fishes that may be compared with the arcuate nucleus in mammals. GALir perikarya were found also in the nucleus recessus lateralis and in the nucleus recessus posterior. Numerous GALir fibers were present in the telencephalon and diencephalon, whereas only small numbers of fibers were found in the brainstem. In contrast to the situation in mammals, no GALir perikarya were observed in the brainstem areas corresponding to the noradrenergic locus coeruleus and serotonergic raphe nuclei in S. salar. We did not find any coexistence of GALir substances with arginine vasotocin or isotocin in neurosecretory neurons, as has been shown for galanin with the mammalian counterparts vasopressin and oxytocin. Also, the galanin-like substance(s) and their structurally closest related peptide family, the tachykinins, belong to separate neuronal systems in teleosts. The presence of GALir neurons in brain areas known to be involved in pituitary control, and a massive GALir innervation of the pituitary, strongly indicate a role for galanin-like substances in pituitary control also in teleosts. Furthermore, the presence of extrahypothalamic GALir fibers suggests involvement of galanin-like substances in other brain functions in teleosts. In conclusion, there are general similarities between teleosts and mammals concerning the distribution of galanin-like substances. However, there seem to be substantial differences in their distribution relative to functionally related peptides within the hypothalamo-pituitary system. Whereas galanin appears to be colocalized and released together with vasopressin and oxytocin in mammals, in teleosts the homologous substances are contained within different sets of neurons that innervate the same target, the pituitary.

Amino Acid Sequence↗