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Teleost Fish (teleost + fish)
Selected AbstractsPurification of Matrix Gla Protein From a Marine Teleost Fish, Argyrosomus regius: Calcified Cartilage and Not Bone as the Primary Site of MGP Accumulation in Fish,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2003DC Simes Abstract Matrix Gla protein (MGP) belongs to the family of vitamin K-dependent, Gla-containing proteins, and in mammals, birds, and Xenopus, its mRNA was previously detected in extracts of bone, cartilage, and soft tissues (mainly heart and kidney), whereas the protein was found to accumulate mainly in bone. However, at that time, it was not evaluated if this accumulation originated from protein synthesized in cartilage or in bone cells because both coexist in skeletal structures of higher vertebrates and Xenopus. Later reports showed that MGP also accumulated in costal calcified cartilage as well as at sites of heart valves and arterial calcification. Interestingly, MGP was also found to accumulate in vertebra of shark, a cartilaginous fish. However, to date, no information is available on sites of MGP expression or accumulation in teleost fishes, the ancestors of terrestrial vertebrates, who have in their skeleton mineralized structures with both bone and calcified cartilage. To analyze MGP structure and function in bony fish, MGP was acid-extracted from the mineralized matrix of either bone tissue (vertebra) or calcified cartilage (branchial arches) from the bony fish, Argyrosomus regius,, separated from the mineral phase by dialysis, and purified by Sephacryl S-100 chromatography. No MGP was recovered from bone tissue, whereas a protein peak corresponding to the MGP position in this type of gel filtration was obtained from an extract of branchial arches, rich in calcified cartilage. MGP was identified by N-terminal amino acid sequence analysis, and the resulting protein sequence was used to design specific oligonucleotides suitable to amplify the corresponding DNA by a mixture of reverse transcription-polymerase chain reaction (RT-PCR) and 5,rapid amplification of cDNA (RACE)-PCR. In parallel, ArBGP (bone Gla protein, osteocalcin) was also identified in the same fish, and its complementary DNA cloned by an identical procedure. Tissue distribution/accumulation was analyzed by Northern blot, in situ hybridization, and immunohistochemistry. In mineralized tissues, the MGP gene was predominantly expressed in cartilage from branchial arches, with no expression detected in the different types of bone analyzed, whereas BGP mRNA was located in bone tissue as expected. Accordingly, the MGP protein was found to accumulate, by immunohistochemical analysis, mainly in the extracellular matrix of calcified cartilage. In soft tissues, MGP mRNA was mainly expressed in heart but in situ hybridization, indicated that cells expressing the MGP gene were located in the bulbus arteriosus and aortic wall, rich in smooth muscle and endothelial cells, whereas no expression was detected in the striated muscle myocardial fibers of the ventricle. These results show that in marine teleost fish, as in mammals, the MGP gene is expressed in cartilage, heart, and kidney tissues, but in contrast with results obtained in Xenopus and higher vertebrates, the protein does not accumulate in vertebra of non-osteocytic teleost fish, but only in calcified cartilage. In addition, our results also indicate that the presence of MGP mRNA in heart tissue is due, at least in fish, to the expression of the MGP gene in only two specific cell types, smooth muscle and endothelial cells, whereas no expression was found in the striated muscle fibers of the ventricle. In light of these results and recent information on expression of MGP gene in these same cell types in mammalian aorta, it is likely that the levels of MGP mRNA previously detected in Xenopus, birds, and mammalian heart tissue may be restricted toregions rich in smooth muscle and endothelial cells. Our results also emphasize the need to re-evaluate which cell types are involved in MGP gene expression in other soft tissues and bring further evidence that fish are a valuable model system to study MGP gene expression and regulation. [source] Ultrastructural Studies of Henneguya rhamdia n. sp. (Myxozoa) a Parasite from the Amazon Teleost Fish, Rhamdia quelen (Pimelodidae)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2005EDILSON MATOS Abstract. Henneguya rhamdia n. sp. is described in the gill filaments of the teleost fish Rhamdia quelen, collected from the Peixe Boi River, State of Pará, Brazil. This myxosporean produced spherical to ellipsoidal plasmodia, up to 300 ,m in diameter, which contained developmental stages, including spores. Several dense bodies up to 2 ,m in diameter were observed among the spores. The spore body was ellipsoidal (13.1 ,m in length, 5.2 ,m in width, and 2.5 ,m in thickness) and each of the two valves presented a tapering tail (36.9 ,m in length). These valves surrounded the binucleated sporoplasm cell and two equal ellipsoidal polar capsules (4.7 × 1.1 ,m), which contained 10,11 (rarely 12) polar filament coils. The sporoplasm contained sporoplasmosomes with a laterally eccentric dense structure with a half-crescent section. Based on the data obtained by electron microscopy and on the host specificity, the spores differed from previously described Henneguya species, mainly in their shape and size, number and arrangement of the polar filament coils, and sporoplasmosome morphology. [source] The Nature of Exocytosis in the Yolk Trophoblastic Layer of Silver Arowana (Osteoglossum bicirrhosum) Juvenile, the Representative of Ancient Teleost FishesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 11 2009Marta Jaroszewska Abstract We have chosen the silver arowana (Osteoglossum bicirrhosum), a representative of the most ancient teleost family Osteoglossidae, to address the question of yolk nutrients utilization. Silver arowana have particularly large eggs (1,1.5 cm of diameter) and a unique morphology of the yolk. We present evidence that the yolk cytoplasmic zone (ycz) in the "yolksac juveniles" is a very complex structure involved in sequential processes of yolk hydrolysis, lipoprotein particles synthesis, their transport, and exocytosis. Vacuoles filled with yolk granules in different stages of digestion move from the vitellolysis zone through the ycz to be emptied into the microvillar interspace in the process of exocytosis. The area of the ycz with the abundance of the mitochondria must play an important role in providing energy for both the transport of vacuoles and the release of their contents. Therefore, we postulate that the function of yolk syncytial layer (ysl) as the "early embryonic patterning center" transforms in fish larvae or yolksac juveniles into a predominantly specialized role as the yolk trophoblastic layer (ytl) involved in yolk nutrients utilization. In addition to discovering the mechanism of transformation of the ysl function into ytl function, we suggest that the machinery involved in nutrient mobilization and exocytosis in yolk of arowana yolksac juveniles can be very attractive system for studies of regulatory processes in almost all secretory pathways in animal cells. Anat Rec, 2009. © 2009 Wiley-Liss, Inc. [source] Genetic, Temporal and Developmental Differences Between Melatonin Rhythm Generating Systems in the Teleost Fish Pineal Organ and RetinaJOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2003J. Falcón Abstract Complete melatonin rhythm generating systems, including photodetector, circadian clock and melatonin synthesis machinery, are located within individual photoreceptor cells in two sites in Teleost fish: the pineal organ and retina. In both, light regulates daily variations in melatonin secretion by controlling the activity of arylalkylamine N -acetyltransferase (AANAT). However, in each species examined to date, marked differences exist between the two organs which may involve the genes encoding the photopigments, genes encoding AANAT, the times of day at which AANAT activity and melatonin production peak and the developmental schedule. We review the fish pineal and retinal melatonin rhythm generating systems and consider the evolutional pressures and other factors which led to these differences. [source] The fabp4 gene of zebrafish (Danio rerio) , genomic homology with the mammalian FABP4 and divergence from the zebrafish fabp3 in developmental expressionFEBS JOURNAL, Issue 6 2007Rong-Zong Liu Teleost fishes differ from mammals in their fat deposition and distribution. The gene for adipocyte-type fatty acid-binding protein (A-FABP or FABP4) has not been identified thus far in fishes. We have determined the cDNA sequence and defined the structure of a fatty acid-binding protein gene (designated fabp4) from the zebrafish genome. The polypeptide sequence encoded by zebrafish fabp4 showed highest identity to the Had -FABP or H6-FABP from Antarctic fishes and the putative orthologs from other teleost fishes (83,88%). Phylogenetic analysis clustered the zebrafish FABP4 with all Antarctic fish H6-FABPs and putative FABP4s from other fishes in a single clade, and then with the mammalian FABP4s in an extended clade. Zebrafish fabp4 was assigned to linkage group 19 at a distinct locus from fabp3. A number of closely linked syntenic genes surrounding the zebrafish fabp4 locus were found to be conserved with human FABP4. The zebrafish fabp4 transcripts showed sequential distribution in the developing eye, diencephalon and brain vascular system, from the middle somitogenesis stage to 48 h postfertilization, whereas fabp3 mRNA was located widely in the embryonic and/or larval central nervous system, retina, myotomes, pancreas and liver from middle somitogenesis to 5 days postfertilization. Differentiation in developmental regulation of zebrafish fabp4 and fabp3 gene transcription suggests distinct functions for these two paralogous genes in vertebrate development. [source] The evolution of teleost pigmentation and the fish-specific genome duplicationJOURNAL OF FISH BIOLOGY, Issue 8 2008I. Braasch Teleost fishes have evolved a unique complexity and diversity of pigmentation and colour patterning that is unmatched among vertebrates. Teleost colouration is mediated by five different major types of neural-crest derived pigment cells, while tetrapods have a smaller repertoire of such chromatophores. The genetic basis of teleost colouration has been mainly uncovered by the cloning of pigmentation genes in mutants of zebrafish Danio rerio and medaka Oryzias latipes. Many of these teleost pigmentation genes were already known as key players in mammalian pigmentation, suggesting partial conservation of the corresponding developmental programme among vertebrates. Strikingly, teleost fishes have additional copies of many pigmentation genes compared with tetrapods, mainly as a result of a whole-genome duplication that occurred 320,350 million years ago at the base of the teleost lineage, the so-called fish-specific genome duplication. Furthermore, teleosts have retained several duplicated pigmentation genes from earlier rounds of genome duplication in the vertebrate lineage, which were lost in other vertebrate groups. It was hypothesized that divergent evolution of such duplicated genes may have played an important role in pigmentation diversity and complexity in teleost fishes, which therefore not only provide important insights into the evolution of the vertebrate pigmentary system but also allow us to study the significance of genome duplications for vertebrate biodiversity. [source] Pigmentary function and evolution of tyrp1 gene duplicates in fishPIGMENT CELL & MELANOMA RESEARCH, Issue 6 2009Ingo Braasch Summary The function of the tyrosinase-related protein 1 (Tyrp1) has not yet been investigated in vertebrates basal to tetrapods. Teleost fishes have two duplicates of the tyrp1 gene. Here, we show that the teleost tyrp1 duplicates have distributed the ancestral gene expression in the retinal pigment epithelium (RPE) and melanophores in a species-specific manner. In medaka embryos, tyrp1a expression is found in the RPE and in melanophores while tyrp1b is only expressed in melanophores. In zebrafish embryos, expression of tyrp1 paralogs overlaps in the RPE and in melanophores. Knockdown of each zebrafish tyrp1 duplicate alone does not show pigmentary defects, but simultaneous knockdown of both tyrp1 genes results in the formation of brown instead of black eumelanin accompanied by severe melanosome defects. Our study suggests that the brown melanosome color in Tyrp1-deficient vertebrates is an effect of altered eumelanin synthesis. Black eumelanin formation essentially relies on the presence of Tyrp1 and some of its function is most likely conserved from the common ancestor of bony vertebrates. [source] Epidermal transient down-regulation of retinol - binding protein 4 and mirror expression of apolipoprotein Eb and estrogen receptor 2a during zebrafish fin and scale developmentDEVELOPMENTAL DYNAMICS, Issue 11 2006Angèle Tingaud-Sequeira Abstract Very little is known about the molecular control of skin patterning and scale morphogenesis in teleost fish. We have found radially symmetrical epidermal placodes with down-regulation of retinol - binding protein 4 (rbp4) expression during the initial paired fin and scale morphogenesis in zebrafish (Danio rerio). This finding may be related to changes in keratinocyte cytodifferentiation and/or the integument retinoid metabolism. rbp4 transcripts are expressed afterward in the central epidermis of the scale papilla and gradually extend to the epidermis, covering the growing scale, whereas no transcripts were detected in posterior margin epidermis. In contrast, induction of apolipoprotein Eb (apoeb) and up-regulation of estrogen receptor 2a (esr2a) transcripts were observed in the epidermis at initiator sites of zebrafish ectodermal/dermal appendage morphogenesis. This expression was maintained in the posterior margin epidermis of the formed scales. esr2a was also strongly expressed in neuromasts, whereas no rbp4 and apoeb transcripts were detected in these mechanosensory structures. The observed epidermal molecular events suggest that epidermis patterning is due to an activator,inhibitor mechanism operational at epidermal,dermal interaction sites. rbp4 transcript expression was also strongly down-regulated by 1-phenyl-2-thio-urea (PTU). As this inhibitor is commonly used to block obscuring pigmentation during in situ hybridization studies, this finding suggests that PTU should be used with caution, particularly in studying skin development. Developmental Dynamics 235:3071,3079, 2006. © 2006 Wiley-Liss, Inc. [source] Ganglion cell regeneration following whole-retina destruction in zebrafishDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2008Tshering Sherpa Abstract The retinas of adult teleost fish can regenerate neurons following injury. The current study provides the first documentation of functional whole retina regeneration in the zebrafish, Danio rerio, following intraocular injection of the cytotoxin, ouabain. Loss and replacement of laminated retinal tissue was monitored by analysis of cell death and cell proliferation, and by analysis of retina-specific gene expression patterns. The spatiotemporal process of retinal ganglion cell (RGC) regeneration was followed through the use of selective markers, and was found to largely recapitulate the spatiotemporal process of embryonic ganglion cell neurogenesis, over a more protracted time frame. However, the re-expression of some ganglion cell markers was not observed. The growth and pathfinding of ganglion cell axons was evaluated by measurement of the optic nerve head (ONH), and the restoration of normal ONH size was found to correspond to the time of recovery of two visually-mediated behaviors. However, some abnormalities were noted, including overproduction of RGCs, and progressive and excessive growth of the ONH at longer recovery times. This model system for whole-retina regeneration has provided an informative view of the regenerative process. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Seasonal plasticity of brain aromatase mRNA expression in glia: Divergence across sex and vocal phenotypesDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005Paul M. Forlano Abstract Although teleost fishes have the highest levels of brain aromatase (estrogen synthase) compared to other vertebrates, little is known of its regulation and function in specific brain areas. Previously, we characterized the distribution of aromatase in the brain of midshipman fish, a model system for identifying the neural and endocrine basis of vocal-acoustic communication and alternative male reproductive tactics. Here, we quantified seasonal changes in brain aromatase mRNA expression in the inter- and intrasexually dimorphic sonic motor nucleus (SMN) and in the preoptic area (POA) in males and females in relation to seasonal changes in circulating steroid hormone levels and reproductive behaviors. Aromatase mRNA expression was compared within each sex throughout non-reproductive, pre-nesting, and nesting periods as well as between sexes within each season. Intrasexual (male) differences were also compared within the nesting period. Females had higher mRNA levels in the pre-nesting period when their steroid levels peaked, while acoustically courting (type I) males had highest expression during the nesting period when their steroid levels peaked. Females had significantly higher levels of expression than type I males in all brain areas, but only during the pre-nesting period. During the nesting period, non-courting type II males had significantly higher levels of aromatase mRNA in the SMN but equivalent levels in the POA compared to type I males and females. These results demonstrate seasonal and sex differences in brain aromatase mRNA expression in a teleost fish and suggest a role for aromatase in the expression of vocal-acoustic and alternative male reproductive phenotypes. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source] Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south-eastern BrazilACTA ZOOLOGICA, Issue 4 2010Yuri Simões Martins Abstract Martins, Y.S., Moura, D.F., Santos, G.B., Rizzo, E. and Bazzoli, N. 2009. Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south-eastern Brazil. ,Acta Zoologica (Stockholm). 91: 466,473. This study provides a comparative analysis of gametogenesis of neotropical teleosts Metynnis maculatus, Megalancistrus parananus, Cichla kelberi and Satanoperca pappaterra, through histological, histochemical and histometric techniques. In the ooplasm of C. kelberi and S. pappaterra conspicuous lipid vesicles were observed, which are characteristic of pelagic eggs produced by marine fishes. Perinucleolar oocytes were identified in the testis of S. pappaterra suggesting that this species is protogynous without functional hermaphroditism, an unusual pattern for neotropical fresh-water fishes. The spermatozoa of the studied species have rounded heads, a characteristic of fish that externally fertilise their eggs. The follicular (granulosa) cells of the vitellogenic oocytes from the studied species were cuboidal or columnar, however, in C. kelberi there were columnar follicular cells at the vegetal pole and cuboidal cells at the animal pole. Variations of the histochemical content were detected in the cortical alveoli and follicular cells of vitellogenic oocytes showing differences in the mechanisms to block polyspermy and egg adhesiveness. Larger oocytes were recorded in species which demonstrated parental care behaviour and smaller oocytes were noted in those species with fractioned spawning. [source] Influence of the SCGE protocol on the amount of basal DNA damage detected in the Mediterranean mussel, Mytilus galloprovincialisENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 8 2006Nicola Machella Abstract Genotoxicity studies using the single cell gel electrophoresis (SCGE) assay indicate that basal levels of DNA strand breaks (SBs) in marine invertebrates are higher and more variable than those in marine vertebrates. This elevated level of DNA damage was attributed to a large number of alkali-labile sites, which are characteristic of the tightly-packaged DNA in invertebrate cells. To investigate if altering the SCGE protocol can artificially modulate high levels of SBs, SCGE experiments were performed on haemocytes from the Mediterranean mussel (Mytilus galloprovincialis) using proteinase K (PK) digestion in combination with assay buffers containing various concentrations of EDTA. In addition, the effects of Trolox® (soluble antioxidant) and aurintricarboxylic acid (ATA; inhibitor of Ca2+/Mg2+ -dependent nucleases) also were tested. The levels of SBs in M. galloprovicialis cells were compared with SBs in cells from a terrestrial mollusk (the snail Helix aspersa), and a teleost fish (the seabass Dicentrarchus labrax). The integrity of M. galloprovincialis DNA isolated with phenol extractions using EDTA, Trolox, and ATA was further assayed by gel electrophoresis. High SBs in mussel cells were reduced by combining EDTA with PK digestion, or using Trolox® or ATA during cell processing for the SCGE assay. Snails and seabass had lower levels of SBs in the SCGE assay, and the levels were not affected by the protocol modifications. Adding EDTA, Trolox®, or ATA to phenol extractions of M. galloprovincialis genomic DNA also reduced the extent of DNA fragmentation. These results suggest that the internal fluids of M. galloprovincialis may increase the basal levels of DNA SBs through oxidative and/or enzyme-mediated pathways. M. galloprovincialis is used extensively as a sentinel species for assessing the genotoxic hazard of marine pollutants. Our data suggest that the SCGE protocol should be carefully considered when assessing DNA damage in these species. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source] Cadmium tolerance in the Nile tilapia (Oreochromis niloticus) following acute exposure: Assessment of some ionoregulatory parametersENVIRONMENTAL TOXICOLOGY, Issue 1 2006Sofia Garcia-Santos Abstract The Nile tilapia (Oreochromis niloticus) can tolerate very high levels of waterborne cadmium. It has one of the highest 96 h LC50 recorded for a freshwater teleost fish (14.8 mg/L Cd; hardness 50 mg/L CaCO3). Cadmium is known to perturb ion balance in teleost fishes. However, in an acute time course experiment, plasma Na+ concentrations were unaffected, and plasma Ca2+ values only decreased after 96 h exposure in a dose-independent manner. Branchial Na+/K+ -ATPase activity and ,-subunit protein level expression in crude gill homogenates were not affected by Cd exposure during this period. Branchial chloride cell numbers, identified as Na+/K+ -ATPase immunoreactive cells using immunohistochemistry, decreased 24 h after exposure but recovered thereafter. Histopathological changes did not follow a consistent pattern of variation with exposure time, and the alterations noted in gill epithelium were basically nonspecific to cadmium. Because of its tolerance, it can be concluded that the tilapia O. niloticus would not be a suitable test organism to evaluate sublethal toxicity of cadmium and the realistic impact of this pollutant in the environment. However, it certainly could contribute significantly to our understanding of the toxic mechanism of cadmium exposure in aquatic organisms. This is the first work to investigate the effect of waterborne pollutants on Na+/K+ -ATPase ,-subunit protein expression in fish gills. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 33,46, 2006. [source] Effects of salinity on copper accumulation in the common killifish (Fundulus heteroclitus)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2005Jonathan Blanchard Abstract Results of laboratory and field studies have demonstrated that salinity influences the accumulation of copper. The present study is, to our knowledge, the first to examine the effect of salinity on copper accumulation in a teleost fish across a comprehensive range of salinity from freshwater to seawater. This was done in an effort to identify potential target tissues and differences in chemical interactions across salinities that will aid in the development of a seawater biotic ligand model (BLM) for copper. Killifish (Fundulus heteroclitus) were acclimated to five salinities (0, 5, 11, 22, and 28 ppt) and exposed to three copper concentrations (0 [nominal], 30, and 150 ,g L,1), yielding 15 treatment groups. Fish from each group were sampled for tissue copper analysis at 0, 4, 12, and 30 d postexposure. Whole-body and liver accumulations were highest at lower salinities. The liver accounted for 57 to 86% of the whole-body copper even though it accounted for less than 4% of the body mass. Similarly, the gill accumulated more copper at lower salinities, whereas the intestine generally accumulated more copper at higher salinities. Speciation calculations indicate that CuCO3 likely accounts for much of the accumulation, possibly with some contributions from CuOH+ and Cu(OH)2. The free ion, Cu2+, does not appear to be associated with copper accumulation. However, the differences in physiology and in the concentrations of competing cations across salinities suggest that speciation alone cannot explain accumulation. The present findings may have implications for future development of a BLM for saline environments by identifying potential target tissues. [source] Ontogeny of Acoustic and Feeding Behaviour in the Grey Gurnard, Eutrigla gurnardusETHOLOGY, Issue 3 2005M. Clara P. Amorim Although sound production in teleost fish is often associated with territorial behaviour, little is known of fish acoustic behaviour in other agonistic contexts such as competitive feeding and how it changes during ontogeny. The grey gurnard, Eutrigla gurnardus, frequently emits knock and grunt sounds during competitive feeding and seems to adopt both contest and scramble tactics under defensible resource conditions. Here we examine, for the first time, the effect of fish size on sound production and agonistic behaviour during competitive feeding. We have made sound (alone) and video (synchronized image and sound) recordings of grey gurnards during competitive feeding interactions. Experimental fish ranged from small juveniles to large adults and were grouped in four size classes: 10,15, 15,20, 25,30 and 30,40 cm in total length. We show that, in this species, both sound production and feeding behaviour change with fish size. Sound production rate decreased in larger fish. Sound duration, pulse duration and the number of pulses increased whereas the peak frequency decreased with fish size, in both sound types (knocks and grunts). Interaction rate and the frequency of agonistic behaviour decreased with increasing fish size during competitive feeding sessions. The proportion of feeding interactions accompanied by sound production was similar in all size classes. However, the proportion of interactions accompanied by knocks (less aggressive sounds) and by grunts (more aggressive) increased and decreased with fish size, respectively. Taken together, these results suggest that smaller grey gurnards compete for food by contest tactics whereas larger specimens predominantly scramble for food, probably because body size gives an advantage in locating, capturing and handling prey. We further suggest that sounds emitted during feeding may potentially give information on the motivation and ability of the individual to compete for food resources. [source] EVOLUTION OF MOUTHBROODING AND LIFE-HISTORY CORRELATES IN THE FIGHTING FISH GENUS BETTAEVOLUTION, Issue 4 2004Lukas Rüber Abstract The origin of and evolutionary transitions among the extraordinary diverse forms of parental care in teleost fish remain largely unknown. The "safe harbor" hypothesis predicts that the evolution from a "guarding" to a "brooding" form of care in teleost fish is associated with shifts in reproductive and life-history features such as reduced fecundity, and increased egg volume with higher parental investment. Robust phylogenetic hypotheses may help to identify evolutionary changes in key traits associated with differences in the form of parental care. Here, we used reconstruction of ancestral character states to study the evolution of the two forms of parental care, bubble nesting and mouthbrooding in the fighting fish genus Betta. We also applied a comparative analysis using the phylogenetic generalized least-squares method to test the "safe harbor" hypothesis by evaluating differences between the two forms of parental care in standard length, life-history traits, and three habitat variables. Evolutionary hypotheses were derived from the first molecular phylogeny (nuclear and mitochondrial DNA sequence data; 4448 bp) of this speciose group. Ancestral character state reconstructions of the evolution of the form of parental care in the genus Betta, using the methods of unweighted parsimony and maximum likelihood, are uncertain and further indicate a high rate of evolutionary transitions. Applying different weights for the suspected directionality of changes, based on the consistent phenotypic and behavioral differences found between bubble nesters and mouthbrooders, recurrent origin of mouthbrooding in the genus Betta is favored using parsimony. Our comparative analyses further demonstrate that bubble nesters and mouthbrooders do not have a consistent set of life-history correlates. The form of parental care in Betta is correlated only with offspring size, with mouthbrooders having significantly bigger offspring than bubble nesters, but is not correlated with egg volume, clutch size, and broodcare duration, nor with any of the three habitat variables tested. Our results thus challenge the general predictions of the "safe harbor" hypothesis for the evolution of alternative brood care forms in the fighting fish genus Betta. [source] On the origin of the chordate central nervous system: expression of onecut in the sea urchin embryoEVOLUTION AND DEVELOPMENT, Issue 4 2004Albert J. Poustka Summary We identified a transcription factor of the onecut class in the sea urchin Strongylocentrotus purpuratus that represents an ortholog of the mammalian gene HNF6, the founding member of the onecut class of proteins. The isolated sea urchin gene, named SpOnecut, encodes a protein of 483 amino acids with one cut domain and a homeodomain. Phylogenetic analysis clearly places the sea urchin gene into this family, most closely related to the ascidian onecut gene HNF-6. Nevertheless, phylogenetic analysis reveals a difficult phylogeny indicating that certain members of the family evolve more rapidly than others and also that the cut domain and homeodomain evolve at a different pace. In fly, worm, ascidian, and teleost fish, the onecut genes isolated so far are exclusively expressed in cells of the central nervous system (CNS), whereas in mammals the two copies of the gene have acquired additional functions in liver and pancreas development. In the sea urchin embryo, expression is first detected in the emerging ciliary band at the late blastula stage. During the gastrula stage, expression is limited to the ciliary band. In the early pluteus stage, SpOnecut is expressed at the apical organ and the elongating arms but continues most prominently in the ciliary band. This is the first gene known that exclusively marks the ciliary band and therein the apical organ in a pluteus larva, whereas chordate orthologs execute essential functions in dorsal CNS development. The significance of this finding for the hypothesis that the ciliary bands and apical organs of the hypothetical "dipleurula"-like chordate ancestor and the chordate/vertebrate CNS are of common origin is discussed. [source] Potential role of radial glia in adult neurogenesis of teleost fishGLIA, Issue 1 2003Günther K.H. Zupanc Abstract Persistence of radial glia within the adult central nervous system is a widespread phenomenon among fish. Based on a series of studies in the teleost species Apteronotus leptorhynchus, we propose that one function of this persistence is the involvement of radial glia in adult neurogenesis, i.e., the generation and further development of new neurons in the adult central nervous system. In particular, evidence has been obtained for the involvement of radial glia in the guidance of migrating young neurons in both the intact and the regenerating brain; for a possible role as precursor cells from which new neurons arise; and for its role as a source of trophic substances promoting the generation, differentiation, and/or survival of new neurons. These functions contribute not only to the potential of the intact brain to generate new neurons continuously, and of the injured brain to replace damaged cells by newly generated ones, but they also provide an essential part of the cellular substrate of behavioral plasticity. GLIA 43:77,86, 2003. © 2003 Wiley-Liss, Inc. [source] Purification of Matrix Gla Protein From a Marine Teleost Fish, Argyrosomus regius: Calcified Cartilage and Not Bone as the Primary Site of MGP Accumulation in Fish,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2003DC Simes Abstract Matrix Gla protein (MGP) belongs to the family of vitamin K-dependent, Gla-containing proteins, and in mammals, birds, and Xenopus, its mRNA was previously detected in extracts of bone, cartilage, and soft tissues (mainly heart and kidney), whereas the protein was found to accumulate mainly in bone. However, at that time, it was not evaluated if this accumulation originated from protein synthesized in cartilage or in bone cells because both coexist in skeletal structures of higher vertebrates and Xenopus. Later reports showed that MGP also accumulated in costal calcified cartilage as well as at sites of heart valves and arterial calcification. Interestingly, MGP was also found to accumulate in vertebra of shark, a cartilaginous fish. However, to date, no information is available on sites of MGP expression or accumulation in teleost fishes, the ancestors of terrestrial vertebrates, who have in their skeleton mineralized structures with both bone and calcified cartilage. To analyze MGP structure and function in bony fish, MGP was acid-extracted from the mineralized matrix of either bone tissue (vertebra) or calcified cartilage (branchial arches) from the bony fish, Argyrosomus regius,, separated from the mineral phase by dialysis, and purified by Sephacryl S-100 chromatography. No MGP was recovered from bone tissue, whereas a protein peak corresponding to the MGP position in this type of gel filtration was obtained from an extract of branchial arches, rich in calcified cartilage. MGP was identified by N-terminal amino acid sequence analysis, and the resulting protein sequence was used to design specific oligonucleotides suitable to amplify the corresponding DNA by a mixture of reverse transcription-polymerase chain reaction (RT-PCR) and 5,rapid amplification of cDNA (RACE)-PCR. In parallel, ArBGP (bone Gla protein, osteocalcin) was also identified in the same fish, and its complementary DNA cloned by an identical procedure. Tissue distribution/accumulation was analyzed by Northern blot, in situ hybridization, and immunohistochemistry. In mineralized tissues, the MGP gene was predominantly expressed in cartilage from branchial arches, with no expression detected in the different types of bone analyzed, whereas BGP mRNA was located in bone tissue as expected. Accordingly, the MGP protein was found to accumulate, by immunohistochemical analysis, mainly in the extracellular matrix of calcified cartilage. In soft tissues, MGP mRNA was mainly expressed in heart but in situ hybridization, indicated that cells expressing the MGP gene were located in the bulbus arteriosus and aortic wall, rich in smooth muscle and endothelial cells, whereas no expression was detected in the striated muscle myocardial fibers of the ventricle. These results show that in marine teleost fish, as in mammals, the MGP gene is expressed in cartilage, heart, and kidney tissues, but in contrast with results obtained in Xenopus and higher vertebrates, the protein does not accumulate in vertebra of non-osteocytic teleost fish, but only in calcified cartilage. In addition, our results also indicate that the presence of MGP mRNA in heart tissue is due, at least in fish, to the expression of the MGP gene in only two specific cell types, smooth muscle and endothelial cells, whereas no expression was found in the striated muscle fibers of the ventricle. In light of these results and recent information on expression of MGP gene in these same cell types in mammalian aorta, it is likely that the levels of MGP mRNA previously detected in Xenopus, birds, and mammalian heart tissue may be restricted toregions rich in smooth muscle and endothelial cells. Our results also emphasize the need to re-evaluate which cell types are involved in MGP gene expression in other soft tissues and bring further evidence that fish are a valuable model system to study MGP gene expression and regulation. [source] The evolution of electroreception and bioelectrogenesis in teleost fish: a phylogenetic perspectiveJOURNAL OF FISH BIOLOGY, Issue 6 2001J. A. Alves-Gomes According to current phylogenetic theory, both electroreceptors and electric organs evolved multiple times throughout the evolution of teleosts. Two basic types of electroreceptors have been described: ampullary and tuberous electroreceptors. Ampullary-type electroreceptors appeared once in the common ancestor of the Siluriformes+Gymnotiformes (within the superorder Ostariophysi), and on two other occasions within the superorder Osteoglossomorpha: in the African Mormyriformes and in the African Notopteriformes. Tuberous receptors are assumed to have evolved three times; all within groups that already possessed ampullary receptors. With the exception of a single catfish species, for which studies are still lacking, all fish with tuberous electroreceptors also have an electric organ. Tuberous electroreceptors are found in the two unrelated electrogenic teleost lineages (orders Gymnotiformes and Mormyriformes) and in one non-electrogenic South American catfish species (order Siluriformes). Electric organs evolved eight times independently among teleosts: five of them among the ostariophysans (once in the gymnotiform ancestor and in four siluriform lineages), once in the common ancestor of Mormyriformes, and in two uranoscopids. With the exception of two uranoscopid genera, for which no electroreceptive capabilities have been discovered so far, all electric organs evolved as an extension of a pre-existing electroreceptive (ampullary) condition. It is suggested that plesiomorphic electric organ discharges (EODs) possessed a frequency spectrum that fully transgressed the tuning curve of ampullary receptors, i.e. a signal such as a long lasting monophasic pulse. Complex EOD waveforms appeared as a derived condition among electric fish. EODs are under constant evolutionary pressure to develop an ideal compromise between a function that enhances electrolocation and electrocommunication capabilities, and thereby ensures species identity through sexual and behavioural segregation, and minimizes the risk of predation. [source] Major histocompatibility complex variability in the clonal Amazon molly, Poecilia formosa: is copy number less important than genotype?MOLECULAR ECOLOGY, Issue 6 2009K. P. LAMPERT Abstract The evolution of sex is still a major unsolved puzzle in biology. One of the most promising theoretical models to answer this question is the Red Queen hypothesis. The Red Queen hypothesis proposes a fast adaptation of pathogens to common genotypes and therefore a negative frequency-dependent selection against common genotypes. Clonal organisms should be especially endangered when co-occurring with closely related sexual species. In this context, major histocompatibility (MHC) genes have been discussed to be auspicious candidates that could provide the genetic basis on which selection for immune competence could act. In this study, we investigated MHC variability in a clonal teleost fish: the Amazon molly, Poecilia formosa. The Amazon molly is an ideal candidate to test the Red Queen hypothesis as it is a clonal species but co-occurs with a closely related sexual species and should therefore be especially susceptible to pathogen infection. We found that allele numbers did in general not differ between sexual and clonal ,species' but that genotypic variability is reduced in the clonally reproducing fish, especially in the polyploids. We conclude that in clonal organisms, genotype frequency might be more important for immune competence than MHC allele number. Amazon mollies and their co-occurring parental species clearly fulfil a prerequisite of the Red Queen hypothesis and should therefore provide an ideal system to experimentally test this basic principle probably underlying the evolution of sex. [source] Primers and polymerase chain reaction conditions for DNA barcoding teleost fish based on the mitochondrial cytochrome b and nuclear rhodopsin genesMOLECULAR ECOLOGY RESOURCES, Issue 5 2007RAFAEL G. SEVILLA Abstract This report describes a set of 21 polymerase chain reaction primers and amplification conditions developed to barcode practically any teleost fish species according to their mitochondrial cytochrome b and nuclear rhodopsin gene sequences. The method was successfully tested in more than 200 marine fish species comprising the main Actinopterygii family groups. When used in phylogenetic analyses, its combination of two genes with different evolutionary rates serves to identify fish at the species level. We provide a flow diagram indicating our validated polymerase chain reaction amplification conditions for barcoding and species identification applications as well as population structure or haplotyping analyses, adaptable to high-throughput analyses. [source] High temperature causes masculinization of genetically female medaka by elevation of cortisolMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2010Yuki Hayashi In poikilothermic vertebrates, sex determination is sometimes influenced by environmental factors such as temperature. However, little is known about the molecular mechanisms underlying environmental sex determination. The medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system. Recently, it was reported that XX medaka can be sex-reversed into phenotypic males by high water temperature (HT; 32,34°C) treatment during the sex differentiation period. Here we report that cortisol caused female-to-male sex reversal and that metyrapone (an inhibitor of cortisol synthesis) inhibited HT-induced masculinization of XX medaka. HT treatment caused elevation of whole-body levels of cortisol, while metyrapone suppressed the elevation by HT treatment during sexual differentiation. Moreover, cortisol and 33°C treatments inhibited female-type proliferation of germ cells as well as expression of follicle-stimulating hormone receptor (fshr) mRNA in XX medaka during sexual differentiation. These results strongly suggest that HT induces masculinization of XX medaka by elevation of cortisol level, which, in turn, causes suppression of germ cell proliferation and of fshr mRNA expression. Mol. Reprod. Dev. 77: 679,686, 2010. © 2010 Wiley-Liss, Inc. [source] Neuroendocrine regulation of puberty in fish: Insights from the grey mullet (Mugil cephalus) modelMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2008Josephine N. Nocillado Abstract We investigated the molecular regulation of pubertal development in the grey mullet, Mugil cephalus, a relatively late-maturing teleost fish. We have isolated and characterized the cDNAs of key reproductive genes along the brain,pituitary,gonadal (BPG) axis as well as the promoters of genes that modulate the axis at multiple levels. Together with relevant findings from other model species, we propose a conceptual model of the neuroendocrine regulation of puberty in the female grey mullet. Research areas that warrant further investigation are identified in the model. Mol. Reprod. Dev. 75: 355,361, 2008. © 2007 Wiley-Liss, Inc. [source] Liver receptor homologue-1 (LRH-1) activates the promoter of brain aromatase (cyp19a2) in a teleost fish, the medaka, Oryzias latipesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2007Yuki Ohmuro-Matsuyama Abstract The medaka, Oryzias latipes, like other fish, have two distinct aromatase genes, the ovarian (cyp19a1) and brain (cyp19a2) forms. We previously reported that Ad4BP/SF-1, a member of the NR5A subfamily, plays an important role in the regulation of cyp19a1 expression in medaka ovarian follicles during vitellogenesis. In the present study, we investigated whether liver receptor homologue-1 (LRH-1), another NR5A subfamily member, is involved in the regulation of cyp19a2 expression in the medaka brain. In situ hybridization analysis revealed that LRH-1 was expressed in the hypothalamus, where it colocalized with aromatase (cyp19a2). We then showed by transient transfection assays that LRH-1 was able to increase expression of a cyp19a2 reporter gene in various mammalian cell lines, and that mutation of a putative LRH-1 binding site within the cyp19a2 promoter abolished this effect. Taken together, these findings suggest that LRH-1 plays a role in regulating cyp19a2 expression in the medaka brain. This is the first to demonstrate in vitro the activation of brain aromatase by LRH-1 in the vertebrate brain. Mol. Reprod. Dev. 74: 1065,1071, 2007. © 2007 Wiley-Liss, Inc. [source] Similar gene structure of two Sox9a genes and their expression patterns during gonadal differentiation in a teleost fish, rice field eel (Monopterus albus)MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2003Rongjia Zhou Abstract The Sox9 gene encodes a transcription factor that is critical for testis determination and chondrogenesis in vertebrates. Mutations in human SOX9 cause campomelic dysplasia, a dominant skeletal dysmorphology syndrome often associated with male to female sex reversal. Here we show that the Sox9a gene was duplicated during evolution of the rice field eel, Monopterus albus, a freshwater fish which undergoes natural sex reversal from female to male during its life, and has a haploid genome size (0.6,0.8 pg) that is among the smallest of the vertebrates. The duplicated copies of the gene (named Sox9al and Sox9a2) fit within the Sox9 clade of vertebrates, especially in the Sox9a subfamily, not in the Sox9b subfamily. They have similar structures as revealed by both genomic and cDNA analysis. Furthermore, both Sox9al and Sox9a2 are expressed in testis, ovary, and ovotestis; and specifically in the outer layer (mainly gonocytes) of gonadal epithelium with bipotential capacity to form testis or ovary, suggesting that they have similar roles in gonadal differentiation during sex reversal in this species. The closely related gene structure and expression patterns of the two sox9a genes in the rice field eel also suggest that they arose in recent gene duplication events during evolution of this fish lineage. Mol. Reprod. Dev. 66: 211,217, 2003. © 2003 Wiley-Liss, Inc. [source] Transport of di- and tripeptides in teleost fish intestineAQUACULTURE RESEARCH, Issue 5 2010Tiziano Verri Abstract The initial observation of peptide absorption in fish intestine dates back to 1981, when, in rainbow trout (Oncorhynchus mykiss), the rate of intestinal absorption of the dipeptide glycylglycine (Gly-Gly) was compared in vivo with the rate of absorption of its component amino acid glycine (Gly). The description of the identification of the underlying mechanisms that allow di- and tripeptide transport across the plasma membranes in fish was provided in 1991, when the first evidence of peptide transport activity was reported in brush-border membrane vesicles of intestinal epithelial cells of Mozambique tilapia (Oreochromis mossambicus) by monitoring uptake of radiolabelled glycyl- l -phenylalanine (Gly- l -Phe). Since then, the existence of a carrier-mediated, H+ -dependent transport of di- and tripeptides (H+/peptide cotransport) in the brush-border membrane of fish enterocytes has been confirmed in many teleost species by a variety of biochemical approaches, providing basic kinetics and substrate specificities of the transport activity. In 2003, the first peptide transporter from a teleost fish, i.e. the zebrafish (Danio rerio) PEPtide transporter 1 (PEPT1), was cloned and functionally characterized in the Xenopus laevis oocyte expression system as a low-affinity/high-capacity system. PEPT1 is the protein in brush-border membranes responsible for translocation of intact di- and tripeptides released from dietary protein by luminal and membrane-bound proteases and peptidases. The transporter possesses affinities for the peptide substrates in the 0.1,10 mM range, depending on the structure and physicochemical nature of the substrates. After the molecular and functional characterization of the zebrafish transporter, the interest in PEPT1 in teleost fish has increased and approaches for cloning and functional characterization of PEPT1 orthologues from other fish species, some of them of the highest commercial value, are now underway. In this paper, we provide a brief overview of the transport of di- and tripeptides in teleost fish intestine by recalling the bulk of biochemical, biophysical and physiological observations collected in the pre-cloning era and by recapitulating the more recent molecular and functional data. [source] Evolutionary history of vertebrate appendicular muscleBIOESSAYS, Issue 5 2001Frietson Galis The evolutionary history of muscle development in the paired fins of teleost fish and the limbs of tetrapod vertebrates is still, to a large extent, uncertain. There has been a consensus, however, that in the vertebrate clade the ancestral mechanism of fin and limb muscle development involves the extension of epithelial tissues from the somite into the fin/limb bud. This mechanism has been documented in chondrichthyan, dipnoan, chondrostean and teleost fishes. It has also been assumed that in amniotes, in contrast, individual progenitor cells of muscles migrate from the somites into the limb buds. Neyt et al.(1) now present the exciting finding that in zebrafishes this presumably derived mechanism involving individual cell migration, is present. They conclude, based on data on sharks, zebrafishes, chickens, quails and mice that the derived mechanism was present in the sarcopterygians. This conclusion, however, may be premature in the light of further data available in the literature, which show a highly mosaic distribution of this character in the vertebrate clade. Furthermore, a developmental mode exists that is intermediate between the supposed ancestral and derived modes in teleosts, reptiles and possibly amphibians. BioEssays 23:383,387, 2001. © 2001 John Wiley & Sons, Inc. [source] A comparative view on mechanisms and functions of skeletal remodelling in teleost fish, with special emphasis on osteoclasts and their functionBIOLOGICAL REVIEWS, Issue 2 2009P. Eckhard Witten ABSTRACT Resorption and remodelling of skeletal tissues is required for development and growth, mechanical adaptation, repair, and mineral homeostasis of the vertebrate skeleton. Here we review for the first time the current knowledge about resorption and remodelling of the skeleton in teleost fish, the largest and most diverse group of extant vertebrates. Teleost species are increasingly used in aquaculture and as models in biomedical skeletal research. Thus, detailed knowledge is required to establish the differences and similarities between mammalian and teleost skeletal remodelling, and between distantly related species such as zebrafish (Danio rerio) and medaka (Oryzias latipes). The cellular mechanisms of differentiation and activation of osteoclasts and the functions of teleost skeletal remodelling are described. Several characteristics, related to skeletal remodelling, distinguish teleosts from mammals. These characteristics include (a) the absence of osteocytes in most species; (b) the absence of haematopoietic bone marrow tissue; (c) the abundance of small mononucleated osteoclasts performing non-lacunar (smooth) bone resorption, in addition to or instead of multinucleated osteoclasts; and (d) a phosphorus- rather than calcium-driven mineral homeostasis (mainly affecting the postcranial dermal skeleton). Furthermore, (e) skeletal resorption is often absent from particular sites, due to sparse or lacking endochondral ossification. Based on the mode of skeletal remodelling in early ontogeny of all teleosts and in later stages of development of teleosts with acellular bone we suggest a link between acellular bone and the predominance of mononucleated osteoclasts, on the one hand, and cellular bone and multinucleated osteoclasts on the other. The evolutionary origin of skeletal remodelling is discussed and whether mononucleated osteoclasts represent an ancestral type of resorbing cells. Revealing the differentiation and activation of teleost skeletal resorbing cells, in the absence of several factors that trigger mammalian osteoclast differentiation, is a current challenge. Understanding which characters of teleost bone remodelling are derived and which characters are conserved should enhance our understanding of the process in fish and may provide insights into alternative pathways of bone remodelling in mammals. [source] Seasonal plasticity of brain aromatase mRNA expression in glia: Divergence across sex and vocal phenotypesDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005Paul M. Forlano Abstract Although teleost fishes have the highest levels of brain aromatase (estrogen synthase) compared to other vertebrates, little is known of its regulation and function in specific brain areas. Previously, we characterized the distribution of aromatase in the brain of midshipman fish, a model system for identifying the neural and endocrine basis of vocal-acoustic communication and alternative male reproductive tactics. Here, we quantified seasonal changes in brain aromatase mRNA expression in the inter- and intrasexually dimorphic sonic motor nucleus (SMN) and in the preoptic area (POA) in males and females in relation to seasonal changes in circulating steroid hormone levels and reproductive behaviors. Aromatase mRNA expression was compared within each sex throughout non-reproductive, pre-nesting, and nesting periods as well as between sexes within each season. Intrasexual (male) differences were also compared within the nesting period. Females had higher mRNA levels in the pre-nesting period when their steroid levels peaked, while acoustically courting (type I) males had highest expression during the nesting period when their steroid levels peaked. Females had significantly higher levels of expression than type I males in all brain areas, but only during the pre-nesting period. During the nesting period, non-courting type II males had significantly higher levels of aromatase mRNA in the SMN but equivalent levels in the POA compared to type I males and females. These results demonstrate seasonal and sex differences in brain aromatase mRNA expression in a teleost fish and suggest a role for aromatase in the expression of vocal-acoustic and alternative male reproductive phenotypes. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source] | ||||||||||||||||||||||||||||||||||