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Otomar Linhart - One of the best experts on this subject based on the ideXlab platform.
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Comparison of oxidant and antioxidant status of seminal plasma and spermatozoa of several fish species
Czech Journal of Animal Science, 2018Co-Authors: Anna Shaliutina-kolešová, Jacky Cosson, Ievgeniia Gazo, Otomar LinhartAbstract:Oxidant and antioxidant activity in seminal plasma was compared with that in spermatozoa of teleost (common carp Cyprinus carpio and brook trout Salvelinus fontinalis) and Chondrostean (Russian stur - geon Acipenser gueldenstaedtii, Siberian sturgeon Acipenser baerii, and sterlet Acipenser ruthenus) fishes. No differences were found between seminal plasma and spermatozoa in the level of thiobarbituric-acid-reactive substance (0.24 ± 0.08 to 0.33 ± 0.04 nmol/mg proteins) in Russian sturgeon, Siberian sturgeon , and sterlet. Carbonyl protein concentration was significantly higher in spermatozoa than in seminal plasma of all studied species. Analyzed antioxidants included superoxide dismutase, glutathione reductase, and glutathione peroxi - dase activity. Significant differences ( P < 0.05) were detected between seminal plasma and spermatozoa in total superoxide dismutase (SOD) and glutathione reductase (GR). Total glutathione peroxidase (GPx) activity was significantly higher in brook trout (12.56 ± 3.23 mU/mg proteins) and Russian sturgeon (11.56 ± 3.12 mU/mg proteins) spermatozoa compared to seminal plasma (6.81 ± 1.56 mU/mg proteins in brook trout and 9.56 ± 3.12 mU/mg proteins in Russian sturgeon). This study provides new data on oxidant and antioxidant balance between spermatozoa and seminal plasma that may be of value in the development of methods for artificial reproduction of teleost and Chondrostean species.
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Sperm proteins in teleostean and Chondrostean (sturgeon) fishes
Fish Physiology and Biochemistry, 2009Co-Authors: Ping Li, Martin Hulak, Otomar LinhartAbstract:Sperm proteins in the seminal plasma and spermatozoa of teleostean and Chondrostean have evolved adaptations due to the changes in the reproductive environment. Analysis of the composition and functions of these proteins provides new insights into sperm motility and fertilising abilities, thereby creating possibilities for improving artificial reproduction and germplasm resource conservation technologies (e.g. cryopreservation). Seminal plasma proteins are involved in the protection of spermatozoa during storage in the reproductive system, whereas all spermatozoa proteins contribute to the swimming and fertilising abilities of sperm. Compared to mammalian species, little data are available on fish sperm proteins and their functions. We review here the current state of the art in this field and focus on relevant subjects that require attention. Future research should concentrate on protein functions and their mode of action in fish species, especially on the role of spermatozoa surface proteins during fertilisation and on a description of sturgeon sperm proteins.
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Morphology and ultrastructure of Siberian sturgeon (Acipenser baerii) spermatozoa using scanning and transmission electron microscopy.
Biology of the cell, 2007Co-Authors: Martin Pšenička, S.m. Hadi Alavi, Marek Rodina, David Gela, Jana Nebesarova, Otomar LinhartAbstract:Background information. Available data concerning the sperm morphology of teleost fishes demonstrate wide variation. In the present study, the spermatozoa of Siberian sturgeon (Acipenser baerii Brandt, 1869), a Chondrostean fish, was investigated. In contrast with teleost fish, Chondrostean spermatozoa have a head with a distinct acrosome, whereas other structures, such as a midpiece and a single flagellum, are present in spermatozoa of most species. Results. The average length of the head including the acrosome and the midpiece was 7.01±0.83 μm. Ten posterolateral projections derived from the acrosome were present on a subacrosomal region, with mean lengths of 0.94±0.15 μm and widths of 0.93±0.11 μm. The nucleus consisted of electrodense homogeneous nuclear chromatin. Three intertwining endonuclear canals, bound by membranes, traversed the nucleus longitudinally from the acrosomal end to the basal nuclear fossa region. There were between three and six mitochondria, two types of centrioles (proximal and distal) in the midpiece and two vacuoles composed of lipid droplets. The flagellum (44.75±4.93 μm in length), originating from the centriolar apparatus, had a typical 9+2 eukaryotic flagellar organization. In addition, there was an extracellular cytoplasm canal between the cytoplasmic sheath and the flagellum. Conclusions. A principal components analysis explained the individual morphological variation fairly well. Of the total accumulated variance, 41.45% was accounted for by parameters related to the head and midpiece of the sperm and the length of the flagellum. Comparing the present study with previous studies of morphology of sturgeon spermatozoa, there were large inter- or intra-specific differences that could be valuable taxonomically.
Robert M Dores - One of the best experts on this subject based on the ideXlab platform.
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Characterizing a proopiomelanocortin cDNA cloned from the brain of the Bichir, Polypterus senegalus: evaluating phylogenetic relationships among ray-finned fish.
General and comparative endocrinology, 2003Co-Authors: Brian Bagrosky, Stephanie Lecaude, Phillip B. Danielson, Robert M DoresAbstract:Abstract There is general agreement that the polypteriform fishes, like Polypterus senegalus, constitute a unique lineage in the evolution of the vertebrates. However, the precise position of these fishes had been a point of controversy since the time of Darwin and Huxley. There is now consensus that the polypteriform fishes are members of superorder Actinopterygii. However, within the Actinopterygii, it is still debatable as to whether the polypteriform fishes are an early offshoot of the Actinopterygii or a more recent sister group to the sturgeon and other extant Chondrostean fishes. In this study the sequence of proopiomelanocortin (POMC), the common precursor for the melanocortins and β-endorphin, was used to evaluate the phylogenetic position of the polypteriform fishes relative to other bony fishes. 3′RACE and 5′RACE protocols were used to amplify overlapping regions of a POMC cDNA from the brain of P. senegalus. The full-length POMC cDNA had an open reading frame that encoded 259 amino acids. As seen in most gnathostomes, P. senegalus POMC has three melanocortin sequences (ACTH/α-MSH, γ-MSH, and β-MSH), and a β-endorphin region. For phylogenetic analysis, the following POMC sequences were aligned at the amino acid level and analyzed using a maximum parsimony algorithm: P. senegalus, dogfish, sturgeon A, paddlefish A, sockeye salmon A, tilapia, and gar. The dogfish POMC sequence was used as the out-group. In this analysis the P. senegalus POMC sequence formed a clade with the Chondrostean POMC sequences (sturgeon A and paddlefish A), and not with the neopterygian sequences (sockeye salmon A, tilapia, and gar). P. senegalus POMC is remarkably similar to sturgeon POMC A. In particular, in both precursors there is evidence for degeneration at the proteolytic cleavage site that precedes the γ-MSH sequence. Based on the analysis of this nuclear gene it would appear that P. senegalus belongs to a branch of the chrondrostean lineage rather than representing a lineage of ray-finned fish that is ancestral to the Chondrostean and neoptyergian ray-finned fishes. Alternatively, if the polypteriform fishes are in fact an early offshoot of the Actinopterygii (the traditional view), then the observations made for P. senegalus POMC relative to the Chondrostean POMC sequences is the result of convergence.
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Sturgeon proopiomelanocortin has a remnant of gamma-melanotropin.
Biochemical and biophysical research communications, 1997Co-Authors: Yutaka Amemiya, Robert M Dores, Akiyoshi Takahashi, Hiroshi KawauchiAbstract:For the investigation of the evolution of the proopiomelanocortin (POMC) gene in early ray-finned fishes, nucleotide sequence of POMC cDNA from a Chondrostean fish, the sturgeon has been determined. POMC cDNA was amplified by PCR from double-strand cDNA prepared from sturgeon pituitary and ligated with lambdaZAP II. The POMC cDNA consists of 1079 bp without a poly-A. An open reading frame of the POMC cDNA encodes 263 amino acid residues. Sturgeon POMC contains ACTH, alpha-melanotropin (MSH), beta-MSH and beta-END at positions (115-153), (115-127), (186-202) and (205-238), respectively. Location of POMC(51-72) is homologous to gamma-MSH, whereas the third residue of MSH-core sequence, His-Phe-Arg-Trp, is changed to His. Moreover, there are no basic amino acids to serve as a processing signal on the N-terminal side of POMC(51-72). These structural characteristics suggest that an ancestor of the ray-finned fishes had gamma-MSH, whereas significant mutations occurred during the evolution of Chondrostean fish.
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cloning of a gar lepisosteus osseus gh cdna trends in actinopterygian gh structure
Journal of Molecular Endocrinology, 1996Co-Authors: D A Rubin, Luciano E Marra, John H. Youson, Robert M DoresAbstract:: A cDNA containing the sequence of GH was cloned and sequenced from a pituitary cDNA library for the holostean fish Lepisosteus osseus (common name: gar). The gar GH cDNA contained an open reading frame of 633 nucleotides and a 3' untranslated region (including the terminal codon TAG) of 1058 nucleotides. The overall length of the gar GH cDNA including leader sequence, signal sequence, hormone sequence and 3' untranslated region was 1713 nucleotides. Thus, the gar GH cDNA is the largest vertebrate GH cDNA yet cloned. A comparison of GH sequences from ancient (holostean fishes-gar and bowfin; one Chondrostean fish-the Russian sturgeon) and more modern (27 species of teleosts) members of class Actinopterygii indicate that members of this class have maintained many of the invariant residues deemed necessary for GH folding motifs (intramolecular relationships) observed in mammals.
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A Comparative Analysis of Somatolactin-Related Immunoreactivity in the Pituitaries of Four Neopterygian Fishes and One Chondrostean Fish: An Immunohistochemical Study
General and comparative endocrinology, 1996Co-Authors: Robert M Dores, Luciano E Marra, Nicole E. Hoffman, Tina Chilcutt-ruth, Ana Lancha, Christopher L. Brown, John H. YousonAbstract:Abstract An antiserum to cod somatolactin (SL) was used for immunohistochemical screening of the pars intermedia of two teleosts ( Oreochromis mossambicus and Gymothorax meleagris ), two holostean fishes ( Lepisosteus osseus and Amia calva ), and a Chondrostean fish ( Acipenser fulvescens ) for SL-immunopositive (SL-IR) cells. As expected, a subset of the epithelial cells in the pars intermedia of O. mossambicus (tilapia) was immunopositive for SL, and the remainder of the epithelial cells was immunopositive for α-MSH-specific antiserum (α-MSH-IR). SL-IR was not detected in any of the epithelial cells in the pars intermedia of the moray eel G. meleagris. To determine whether SL-IR could be detected in nonteleost fishes, immunohistochemical analyses were done on the pituitaries of two holostean fishes and one Chondrostean fish. In the pars intermedia of the gar, L. osseus, a subset of cells was immunopositive for both SL and α-MSH. The majority of the pars intermedia cells was immunopositive for α-MSH only. However, in the pars intermedia of the bowfin, A. calva, all of the epithelial cells indicated the presence of both SL and α-MSH. Finally, no SL-positive cells were detected in the pars intermedia of the sturgeon, A. fulvescens.
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Analysis of the Post-translational Processing of α-MSH in the Pituitaries of the Chondrostean Fishes, Acipenser transmontanus and Polyodon spathula
General and comparative endocrinology, 1994Co-Authors: Heidi Keller, J.michael Redding, Gary P. Moberg, Robert M DoresAbstract:Abstract Multiple forms of α-MSH were isolated from the pituitaries of the white sturgeon, Acipenser transmontanus , and the paddlefish, Polyodon spathula , following fractionation of the pituitary extracts by reversed-phase HPLC. In both species, immunoreactive forms which eluted with the same retention times as synthetic mammalian ACTH(1-13)NH 2 , monoacetylated α-MSH, and diacetylated α-MSH were detected. In the pituitary of the sturgeon, N-acetylated forms of α-MSH represented 91% of the total α-MSH isolated. However, in the pituitary of the paddlefish, N-acetylated forms of α-MSH accounted for only 45% of the total α-MSH isolated. The presence of N-acetylated forms of α-MSH in the pituitaries of representatives of the two extant genera of Chondrostean fish coupled with the observation that N-acetylated forms of α-MSH are present in the pituitaries of cladistian and neopterygian fishes indicates that the α-MSH specific N-acetylation mechanism evolved prior to the radiation of the Actinopterygii. A conspicuous feature of the Chondrostean α-MSH N-acetylation reaction was the low levels of diacetylated α-MSH produced relative to the levels of monoacetylated α-MSH. Similar observations have been made for the cladistian fish, Calamoichthys calabaricus , and the cartilaginous fish, Hydrolagus colliei . However, in holostean fishes, lungfishes, and tetrapods, the diacetylated form of α-MSH is the major end product produced in the intermediate pituitary. The phylogenetic implications of these observations will be discussed.
Julián Yáñez - One of the best experts on this subject based on the ideXlab platform.
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Immunohistochemical study of the distribution of calcium binding proteins in the brain of a Chondrostean (Acipenser baeri).
The Journal of comparative neurology, 2012Co-Authors: Patricia Graña, Gema Huesa, Ramón Anadón, Julián YáñezAbstract:Chondrosteans represent an ancient lineage in ray-finned bony fishes and hence in jawed vertebrates. This immunohistochemical study in the brain of the Siberian sturgeon reports the neuronal distribution of three cytosolic calcium-binding proteins: calbindin-D28k (CB), calretinin (CR), and parvalbumin (PV). CB and CR are widely expressed in different neuron subsets distributed throughout the sturgeon brain. Studies using double immunofluorescence reveal a wide co-distribution of CB and CR in the brain nuclei but scarce co-localization at cellular level. In the forebrain, CR- and CB-immunoreactive (ir) populations were observed in the olfactory bulbs, in pallial and subpallial telencephalic areas, and in some diencephalic nuclei. CR-ir cells were also observed in the posterior tubercle and CB-ir cells in the preglomerular complex. At midbrain and hindbrain basal levels, CB-ir and CR-ir cell bodies were mainly distributed in periventricular areas. In the cerebellum, CB and CR cells were co-localized in some granular cell subsets in laterodorsal and dorsolateral regions, and in some Purkinje-like cells. CB-ir and CR-ir fibers were mainly observed in the olfactory bulbs, hypothalamus, and habenula, and in fiber tracts that coursed in the optic tectum and through the mesencephalic and rhombencephalic basal areas. With regard to PV, the sturgeon brain showed a rather limited distribution of PV-ir perikarya and fibers. Thus, CR, CB, and PV allowed the identification of subpopulations of neurons not distinguished on the basis of cytoarchitecture alone, which provided a better understanding of the anatomical organization of the sturgeon brain. These results reveal numerous shared features with teleosts, but also important differences. J. Comp. Neurol. 520:2086–2122, 2012. © 2011 Wiley Periodicals, Inc.
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Topography and connections of the telencephalon in a Chondrostean, Acipenser baeri: an experimental study.
The Journal of comparative neurology, 2006Co-Authors: Gema Huesa, Ramón Anadón, Julián YáñezAbstract:Sturgeons belong to an ancient group of the extant actinopterygian fishes. Accordingly, the study of their brain connections is important to understand brain evolution in the line leading to teleosts. We examined the topography and connections of the various telencephalic regions of the Siberian sturgeon (Acipenser baeri). The telencephalic regions were characterized on the basis of acetylcholinesterase histochemistry and calbindin-D28k and calretinin immunohistochemistry. The telencephalic connections were investigated by using the fluorescent dye DiI (1,1′-dioctadecyl 3,3,3′,3′-tetramethylindocarbocyanine perchlorate) in fixed brains. Application of DiI to different areas of the pallial (dorsal) regions of the telencephalic lobes showed that they have mostly intratelencephalic connections. A posterior pallial region is characterized by its similar hodology to that of the posterior zone of the teleosts dorsal telencephalon and those described in other ancient groups. Extratelencephalic connections of the pallium are scarce, although a few afferent and efferent connections with the diencephalon, mesencephalon, and rostral rhombencephalon were observed. DiI application to subpallial regions showed both intratelencephalic connections and connections with different brain regions. Afferents to the subpallium originate from the olfactory bulbs, preoptic area, thalamus, posterior tuberculum, hypothalamus, secondary gustatory nucleus, and raphe nuclei. Some of these connections are quite similar to those described for other vertebrates. J. Comp. Neurol. 497:519–541, 2006. © 2006 Wiley-Liss, Inc.
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Calbindin and calretinin immunoreactivities in the retina of a Chondrostean, Acipenser baeri.
Cell and tissue research, 2002Co-Authors: Gema Huesa, Julián Yáñez, Ramón AnadónAbstract:The distribution of calbindin and calretinin in the retina of the sturgeon Acipenser baeri was studied with immunocytochemistry. Western blot analysis of brain extracts, together with immunocytochemical results in the retina and brain, indicated the presence of the two calcium-binding proteins in sturgeon. Calbindin immunocytochemistry revealed only a large displaced bipolar cell type with narrowly stratified axons, similar to some mixed rod and cones bipolar cells described in teleosts. The plexus formed by the axons of these cells in the inner plexiform sublayer was similar to that formed by calbindin-immunoreactive diffuse bipolar cells of some mammals. Calretinin immunocytochemistry also stained these displaced bipolar cells, most ganglion cells including displaced ganglion cells (Dogiel cells), and some amacrine cells of the inner nuclear layer. The distribution of calbindin and calretinin immunoreactivities in the retina of a primitive bony fish indicates that these proteins are highly specific to the cell type.
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Olfactory projections in a Chondrostean fish, Acipenser baeri: an experimental study.
The Journal of comparative neurology, 2000Co-Authors: Gema Huesa, Ramón Anadón, Julián YáñezAbstract:The presence of extrabulbar primary olfactory projections has been well established in teleosts. In order to investigate the phylogeny of these projections and to compare their targets with those of the secondary olfactory projections, the connections of the olfactory epithelium and olfactory bulb were studied by means of tract-tracing methods in a Chondrostean, Acipenser baeri. Primary olfactory projections mainly extend to the glomerular layer of the olfactory bulb, but a significant number of extrabulbar efferent fibers course to various telencephalic and diencephalic regions. Both extrabulbar primary and olfactory bulb projections course in diffuse pathways. Extensive overlap was observed between the targets of these extrabulbar primary olfactory fibers and those of the secondary efferent projections of the olfactory bulb, though the latter were more numerous and reached additional targets. Tracer application to the olfactory bulb also revealed a number of bulbopetal neurons in the ipsilateral and contralateral telencephalic areas, as well as crossed interbulbar projections. The presence in a Chondrostean of important extrabulbar primary projections and their extensive overlap with secondary olfactory projections suggest that such projections are a derived characteristic of bony fishes. J. Comp. Neurol. 428:145–158, 2000. © 2000 Wiley-Liss, Inc.
Gema Huesa - One of the best experts on this subject based on the ideXlab platform.
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Immunohistochemical study of the distribution of calcium binding proteins in the brain of a Chondrostean (Acipenser baeri).
The Journal of comparative neurology, 2012Co-Authors: Patricia Graña, Gema Huesa, Ramón Anadón, Julián YáñezAbstract:Chondrosteans represent an ancient lineage in ray-finned bony fishes and hence in jawed vertebrates. This immunohistochemical study in the brain of the Siberian sturgeon reports the neuronal distribution of three cytosolic calcium-binding proteins: calbindin-D28k (CB), calretinin (CR), and parvalbumin (PV). CB and CR are widely expressed in different neuron subsets distributed throughout the sturgeon brain. Studies using double immunofluorescence reveal a wide co-distribution of CB and CR in the brain nuclei but scarce co-localization at cellular level. In the forebrain, CR- and CB-immunoreactive (ir) populations were observed in the olfactory bulbs, in pallial and subpallial telencephalic areas, and in some diencephalic nuclei. CR-ir cells were also observed in the posterior tubercle and CB-ir cells in the preglomerular complex. At midbrain and hindbrain basal levels, CB-ir and CR-ir cell bodies were mainly distributed in periventricular areas. In the cerebellum, CB and CR cells were co-localized in some granular cell subsets in laterodorsal and dorsolateral regions, and in some Purkinje-like cells. CB-ir and CR-ir fibers were mainly observed in the olfactory bulbs, hypothalamus, and habenula, and in fiber tracts that coursed in the optic tectum and through the mesencephalic and rhombencephalic basal areas. With regard to PV, the sturgeon brain showed a rather limited distribution of PV-ir perikarya and fibers. Thus, CR, CB, and PV allowed the identification of subpopulations of neurons not distinguished on the basis of cytoarchitecture alone, which provided a better understanding of the anatomical organization of the sturgeon brain. These results reveal numerous shared features with teleosts, but also important differences. J. Comp. Neurol. 520:2086–2122, 2012. © 2011 Wiley Periodicals, Inc.
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Topography and connections of the telencephalon in a Chondrostean, Acipenser baeri: an experimental study.
The Journal of comparative neurology, 2006Co-Authors: Gema Huesa, Ramón Anadón, Julián YáñezAbstract:Sturgeons belong to an ancient group of the extant actinopterygian fishes. Accordingly, the study of their brain connections is important to understand brain evolution in the line leading to teleosts. We examined the topography and connections of the various telencephalic regions of the Siberian sturgeon (Acipenser baeri). The telencephalic regions were characterized on the basis of acetylcholinesterase histochemistry and calbindin-D28k and calretinin immunohistochemistry. The telencephalic connections were investigated by using the fluorescent dye DiI (1,1′-dioctadecyl 3,3,3′,3′-tetramethylindocarbocyanine perchlorate) in fixed brains. Application of DiI to different areas of the pallial (dorsal) regions of the telencephalic lobes showed that they have mostly intratelencephalic connections. A posterior pallial region is characterized by its similar hodology to that of the posterior zone of the teleosts dorsal telencephalon and those described in other ancient groups. Extratelencephalic connections of the pallium are scarce, although a few afferent and efferent connections with the diencephalon, mesencephalon, and rostral rhombencephalon were observed. DiI application to subpallial regions showed both intratelencephalic connections and connections with different brain regions. Afferents to the subpallium originate from the olfactory bulbs, preoptic area, thalamus, posterior tuberculum, hypothalamus, secondary gustatory nucleus, and raphe nuclei. Some of these connections are quite similar to those described for other vertebrates. J. Comp. Neurol. 497:519–541, 2006. © 2006 Wiley-Liss, Inc.
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Calbindin and calretinin immunoreactivities in the retina of a Chondrostean, Acipenser baeri.
Cell and tissue research, 2002Co-Authors: Gema Huesa, Julián Yáñez, Ramón AnadónAbstract:The distribution of calbindin and calretinin in the retina of the sturgeon Acipenser baeri was studied with immunocytochemistry. Western blot analysis of brain extracts, together with immunocytochemical results in the retina and brain, indicated the presence of the two calcium-binding proteins in sturgeon. Calbindin immunocytochemistry revealed only a large displaced bipolar cell type with narrowly stratified axons, similar to some mixed rod and cones bipolar cells described in teleosts. The plexus formed by the axons of these cells in the inner plexiform sublayer was similar to that formed by calbindin-immunoreactive diffuse bipolar cells of some mammals. Calretinin immunocytochemistry also stained these displaced bipolar cells, most ganglion cells including displaced ganglion cells (Dogiel cells), and some amacrine cells of the inner nuclear layer. The distribution of calbindin and calretinin immunoreactivities in the retina of a primitive bony fish indicates that these proteins are highly specific to the cell type.
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Olfactory projections in a Chondrostean fish, Acipenser baeri: an experimental study.
The Journal of comparative neurology, 2000Co-Authors: Gema Huesa, Ramón Anadón, Julián YáñezAbstract:The presence of extrabulbar primary olfactory projections has been well established in teleosts. In order to investigate the phylogeny of these projections and to compare their targets with those of the secondary olfactory projections, the connections of the olfactory epithelium and olfactory bulb were studied by means of tract-tracing methods in a Chondrostean, Acipenser baeri. Primary olfactory projections mainly extend to the glomerular layer of the olfactory bulb, but a significant number of extrabulbar efferent fibers course to various telencephalic and diencephalic regions. Both extrabulbar primary and olfactory bulb projections course in diffuse pathways. Extensive overlap was observed between the targets of these extrabulbar primary olfactory fibers and those of the secondary efferent projections of the olfactory bulb, though the latter were more numerous and reached additional targets. Tracer application to the olfactory bulb also revealed a number of bulbopetal neurons in the ipsilateral and contralateral telencephalic areas, as well as crossed interbulbar projections. The presence in a Chondrostean of important extrabulbar primary projections and their extensive overlap with secondary olfactory projections suggest that such projections are a derived characteristic of bony fishes. J. Comp. Neurol. 428:145–158, 2000. © 2000 Wiley-Liss, Inc.
Yoon Kwon Nam - One of the best experts on this subject based on the ideXlab platform.
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Subfunctionalization and evolution of liver-expressed antimicrobial peptide 2 (LEAP2) isoform genes in Siberian sturgeon (Acipenser baerii), a primitive Chondrostean fish species.
Fish & shellfish immunology, 2019Co-Authors: Chan-hee Kim, Eun Jeong Kim, Yoon Kwon NamAbstract:Two liver-expressed antimicrobial peptide 2 (LEAP2) isoforms were characterized in a primitive Chondrostean sturgeon species, Acipenser baerii (Acipenseriformes). A. baerii LEAP2 isoforms represented essentially common structures shared by their vertebrate orthologs at both genomic (i.e., tripartite organization) and peptide (two conserved disulfide bonds) levels. A. baerii LEAP2 isoforms (designed LEAP2AB and LEAP2C, respectively) phylogenetically occupy the most basal position in the actinopterygian lineage and represent an intermediate character between teleostean and tetrapodian LEAP2s in the sequence alignment. Molecular phylogenetic analysis including LEAP2s from extant primitive fish species indicated that the evolutionary origin of ancestral LEAP2 in vertebrate groups should date back to earlier than the actinopterygian-sarcopterygian split. Gene expression assays under both basal and stimulated conditions suggested that A. baerii LEAP2 isoforms have undergone substantial subfunctionalization in tissue distribution pattern, developmental/ontogenetic expression, and immune responses. LEAP2AB showed a predominant liver expression, while LEAP2C exhibited the highest level of expression in the intestine. LEAP2C was a more dominantly expressed isoform during embryonic development and prelarval ontogeny. The LEAP2AB isoform is more closely associated with innate immune response to microbial invasion, compared with LEAP2C, as evidenced by results from LPS, poly(I:C) and Aeromonas hydrophila challenges. Synthetic mature peptides of LEAP2AB displayed a more potent antimicrobial activity than did LEAP2C. Data from this study could be useful not only to provide deeper insights into the evolutionary mechanism of LEAP2 in the actinopterygian lineage but also to better understand the innate immunity of this commercially important Chondrostean species.
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Chondrostean sturgeon hepcidin: An evolutionary link between teleost and tetrapod hepcidins
Fish & shellfish immunology, 2019Co-Authors: Chan-hee Kim, Eun Jeong Kim, Yoon Kwon NamAbstract:Abstract Hepcidin, a cysteine-rich antimicrobial peptide (AMP), plays key roles as a regulatory hormone in iron homeostasis, providing a link between iron metabolism and innate immunity. Unlike many other AMPs displaying a high degree of sequence variability among closely related organisms, hepcidin is highly conserved from teleosts to mammals. However, little is known about the early ancestry of hepcidins in the vertebrate lineage. Here, we first report potential a prototype hepcidin from the Siberian sturgeon Acipenser baerii, a primitive Chondrostean species. The A. baerii hepcidin (AbHAMP) gene showed a tripartite exon-intron organization, which encoded a precursor protein comprised of three structural signatures containing eight cysteine residues, a common structure in vertebrate hepcidin genes and proteins. mRNA expression by iron-overloading and bacterial infection and antibacterial activity revealed that AbHAMP might play a role in iron metabolism regulator in the liver, and in direct and/or indirect host immune response in the kidney against invading pathogen. Comparison of gene and protein sequences reveled that AbHAMP possesses intermediate characteristics between tetrapodian and teleostean hepcidins (HAMP1s). Phylogenetically, AbHAMP had a closer genetic affiliation to tetrapodian orthologs than to teleostean orthologs, suggesting that the structures of this Chondrostean hepcidin may closely reflect the structures of an evolutionarily ancestral form that might have evolved into extant hepcidins in tetrapods and teleosts, respectively. Based on the identification of hepcidin from the Chondrostean group, the emergence of the common ancestral hepcidin should be traced back to in early Osteichthyes: no later than sarcopterygian (lobe-finned fishes) – actinopterygian (ray-finned fishes) split.