| characterization and function of atp receptors on hepatocytes from the little skate raja erinacea. | hormonal regulation of hepatocytes, via cytosolic ca2+ signaling, is well established in higher life forms but has not been investigated in elasmobranchs. we therefore examined ca2+ signaling in hepatocytes isolated from the little skate, raja erinacea. in hepatocyte populations, atp induced a rapid, biphasic increase in ca2+, as it does in mammalian hepatocytes. other hormones that act on mammalian hepatocytes, such as vasopressin, angiotensin, and phenylephrine, induced no such ca2+ increase. ... | 1996 | 8780221 |
| multiple molecular forms of gonadotropin-releasing hormone in the brain of an elasmobranch: evidence for ir-lamprey gnrh. | these studies investigated brains of skate, raja erinacea (order rajiformes, class chondrichthyes), for gonadotropin-releasing hormone (gnrh) peptides by chromatograph and immunoreactivity with region-specific antisera raised against mammalian gnrh and lamprey gnrh. the region-specific antibody to lamprey gnrh-i was produced following conjugation to bovine serum albumin using the bis-diazotized benzidine method. this antibody was characterized by assaying a range of increasing dilutions of the k ... | 1993 | 8234016 |
| disruption of cell volume regulation by mercuric chloride is mediated by an increase in sodium permeability and inhibition of an osmolyte channel in skate hepatocytes. | the mechanism by which mercury leads to cell swelling and impairs the normal regulatory volume decrease (rvd) in cells swollen in hypotonic media was examined in hepatocytes isolated from the little skate, raja erinacea, an osmoconforming marine elasmobranch. skate hepatocytes treated with 50 microm hgcl2 in isotonic medium swelled to volumes double those of control cells, and this was associated with an increase in na+ and k+ permeability. the gain in intracellular na+ exceeded the k+ loss by 0 ... | 1996 | 8887458 |
| a role for gabaergic inhibition in electrosensory processing and common mode rejection in the dorsal nucleus of the little skate, raja erinacea. | the electrosensory primary afferents in elasmobranchs are responsive to electric potentials created by the animal's own ventilation, while the second-order neurons (aens) which receive this afferent input in the medulla suppress responses to ventilatory potentials but retain their extreme sensitivity to electric signals in the environment. ventilatory potentials are common mode signals in elasmobranchs and a common mode rejection mechanism is one way the aens suppress ventilatory noise. by press ... | 1996 | 8956498 |
| band 3 in cell volume regulation in fish erythrocytes. | erythrocytes of the skate (raja erinacea) demonstrate a regulatory volume decrease response when exposed to hypotonic stress by releasing taurine and other organic osmolytes. we review the transport characteristics, physical changes and signaling pathways of a volume-activated osmolyte channel associated with band 3 in skate red blood cells that can be distinguished from anion channels and is separate from the anion exchanger function of band 3. | 1996 | 8960774 |
| characterization of bumetanide transport in isolated skate hepatocytes. | the uptake of [3h]bumetanide was studied in isolated skate hepatocytes in an albumin-free elasmobranch ringer solution and compared with the uptake of bile acids in the presence of other cholephilic organic anions. [3h]bumetanide uptake was energy dependent, temperature sensitive, and exhibited saturation kinetics. in contrast to taurocholate and cholate, which are transported only by na(+)-independent mechanisms, removal of na+ reduced the maximal uptake rate (vmax) for bumetanide from 404 +/- ... | 1993 | 8238522 |
| volume-regulatory amino acid transport in erythrocytes of the little skate, raja erinacea. | skate erythrocytes swell in a hypotonic medium and then reduce their volume mainly by releasing the beta-amino acids taurine and beta-alanine. although these amino acids exhibit a net efflux, na(+)-independent influx is also increased. both the reduction in cell volume and increase in amino acid transport are inhibited by several inhibitors of band 3-mediated anion transport, including 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (dids) [l. goldstein and s. r. brill, am. j. physiol. 260 (reg ... | 1993 | 8342684 |
| chloride and taurine effluxes occur by different pathways in skate erythrocytes. | the aim of this study was to determine whether volume-activated taurine and cl- effluxes occur via the same system in skate (raja erinacea) red blood cells (rbc). the effluxes were measured in isotonic and hypotonic elasmobranch ringer solutions, in which nacl was replaced by mannitol and the remaining exchangeable anions with gluconate. methazolamide (0.1 mm) was added to minimize hco3- formation. rbc cl- content fell approximately 50%/h in both isotonic and hypotonic media, with no detectable ... | 1996 | 8997351 |
| two classes of bipolar cell in the retina of the skate raja erinacea. | we have used immunoreactions against serotonin and protein kinase c to visualize two distinct classes of bipolar cell in the all-rod retina of the skate, raja erinacea. to enhance the immunoreaction in serotonin-accumulating bipolar cells, prior to fixation, some retinas were incubated in ringer's solution containing serotonin and pargyline. we found the somata of serotonin-accumulating bipolar cells to be located slightly distal to the midline of the inner nuclear layer. with increasing eccentr ... | 1996 | 9013424 |
| distinct but overlapping populations of commissural and gabaergic neurons in the dorsal nucleus of the little skate, raja erinacea. | in the little skate, raja erinacea, the electrosensory primary afferents are responsive to electrical potentials created during the animal's own ventilation, while second-order electrosensory cells in the dorsal nucleus of the medulla suppress the responses to ventilatory potentials but retain their extreme sensitivity to important environmental electric signals. previous electrophysiological studies indicate a role for a commissural pathway between the bilateral dorsal nuclei in ventilatory noi ... | 1997 | 9031733 |
| characteristics of renal na(+)-d-glucose cotransport in the skate (raja erinacea) and shark (squalus acanthias). | we have investigated the properties of the skate (raja erinacea) and shark (squalus acanthias) kidney na(+)-d-glucose cotransporters (sglt) in uptake studies of radiolabeled substrates into isolated renal brush-border membrane vesicles (bbmv). scatchard plot analysis of the substrate dependence revealed that the na(+)-d-glucose cotransporter population is homogenous within each species. skate bbmv showed a relatively high affinity for d-glucose [michaelis constant (k(m)) = 0.12 mm] with an appar ... | 1997 | 9249542 |
| molecular cloning of a rod opsin cdna from the skate retina. | skates (raja erinacea and r. ocellata) are among the few animals that have an exclusively rod retina. however, skate rods are unusual in that they are capable of adapting to extremely high levels of illumination that initially saturate the rod photocurrent. this adaptive process restores the ability of the visual cells to respond to incremental photic stimuli and enables them to function under ambient conditions that are subserved by the cone mechanism in mixed (rod/cone) retinae. as a first ste ... | 1997 | 9256070 |
| ventilatory modes and mechanics of the hedgehog skate (leucoraja erinacea): testing the continuous flow model. | the movement of water across the gills of non-ram-ventilating fishes involves the action of two pumps: a pressure pump that pushes water across the gills from the oropharyngeal to the parabranchial cavity, and a suction pump that draws water across the gills from the oropharyngeal into the parabranchial cavity. together, the two are thought to keep water flowing continuously anteroposteriorly through the head of the respiring animal. however, there is evidence that the pressure and suction pumps ... | 2001 | 11398747 |
| high affinity binding of ankyrin induced by volume expansion in skate erythrocytes. | volume expansion of little skate (raja erinacea) erythrocytes increases the affinity of ankyrin binding without altering in the number of binding sites. potassium iodide-stripped inside-out vesicles (ki-iov) were used to assess ankyrin binding under volume-expanded conditions. under isoosmotic conditions, ankyrin binds nearly exclusively to a single class of sites (bmax, 52 +/- 12 microg/mg; kd, 150 +/- 28 nm). ki-iov from volume-expanded cells (either with one-half osmolarity medium or with inc ... | 1996 | 8702894 |
| expression cloning of two genes that together mediate organic solute and steroid transport in the liver of a marine vertebrate. | uptake of organic solutes and xenobiotics by mammalian cells is mediated by atp-independent transporters, and four families of transporters have now been identified. to search for novel organic solute transporters, a liver cdna library from an evolutionarily primitive marine vertebrate, the little skate raja erinacea, was screened for taurocholate transport activity by using xenopus laevis oocytes. in contrast to the organic anion transporters identified to date, a transport activity was identif ... | 2001 | 11470901 |
| motor corollary discharge activity and sensory responses related to ventilation in the skate vestibulolateral cerebellum: implications for electrosensory processing | the dorsal granular ridge (dgr) of the elasmobranch vestibulolateral cerebellum is the source of a parallel fiber projection to the electrosensory dorsal nucleus. we report that the dgr in raja erinacea contains a large percentage of units with activity modulated by the animal's own ventilation. these include propriosensory and electrosensory units, responding to either ventilatory movements or the resulting electroreceptive reafference, and an additional population of units in which activity is ... | 1996 | 9318412 |
| organic osmolyte channels: transport characteristics and regulation. | erythrocytes of the skate (raja erinacea) exposed to hypotonic stress swell and then undergo a volume regulatory decrease by releasing taurine and other osmolytes. previous studies showed that taurine release occurs via a volume-activated, na(+)-independent, bi-directional transporter that has the properties of a size-limited channel. we now report on the transport characteristics of this channel and its regulation. kinetic, competition and inhibitor studies indicate that polyols (myo-inositol) ... | 1996 | 8743479 |
| elasmobranch oculomotor organization: anatomical and theoretical aspects of the phylogenetic development of vestibulo-oculomotor connectivity. | the oculomotor organization of two elasmobranch species, smooth dogfish (mustelus canis) and little skate (raja erinacea), was studied by investigating the extraocular muscle apparatus and the oculomotor motoneuron distribution. the macroscopic appearance of the eye muscles was similar to any lateral-eyed vertebrate species (e.g., goldfish, rabbit). the size of extraocular muscles was expressed by counting single muscle fibers and comparing cross-sectional areas of the extraocular muscles. there ... | 1984 | 6470223 |
| enterohepatic circulation of scymnol sulfate in an elasmobranch, the little skate (raja erinacea). | the sulfated bile alcohol scymnol sulfate (scys), 3 alpha,7 alpha,12 alpha,24 xi, 26,27-hexahydroxy-5 beta-cholestane-26(27)-sulfate, is the major bile salt in bile of an elasmobranch, the little skate. to investigate hepatic transport of bile alcohols in skate liver, [3h]scys and a potential precursor, 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestane (chtriol), were used as model compounds. their transport into isolated hepatocytes was partially saturable, temperature sensitive, and na+ in ... | 1997 | 9374698 |
| short-latency interneurons in the dorsal nucleus of the little skate, raja erinacea. | the elasmobranch electrosensory system is the most thoroughly understood of the non-teleost electrosensory systems and is useful for studying central nervous system mechanisms for the separation of behaviorally relevant signals from self-generated noise. in the little skate, raja erinacea, the electrosensory primary afferents are responsive to electrical potentials created during the animal's own ventilation, while second-order neurons in the dorsal nucleus of the medulla suppress responses to v ... | 1997 | 9383011 |
| molecular evolution of two vertebrate aryl hydrocarbon (dioxin) receptors (ahr1 and ahr2) and the pas family. | the aryl hydrocarbon receptor (ahr) is a ligand-activated transcription factor through which halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) cause altered gene expression and toxicity. the ahr belongs to the basic helix-loop-helix/per-arnt-sim (bhlh-pas) family of transcriptional regulatory proteins, whose members play key roles in development, circadian rhythmicity, and environmental homeostasis; however, the normal cellular function of the ahr is not yet kn ... | 1997 | 9391097 |
| functional complementation between a novel mammalian polygenic transport complex and an evolutionarily ancient organic solute transporter, ostalpha-ostbeta. | these studies identify an organic solute transporter (ost) that is generated when two novel gene products are co-expressed, namely human ostalpha and ostbeta or mouse ostalpha and ostbeta. the results also demonstrate that the mammalian proteins are functionally complemented by evolutionarily divergent ostalpha-ostbeta proteins recently identified in the little skate, raja erinacea, even though the latter exhibit only 25-41% predicted amino acid identity with the mammalian proteins. human, mouse ... | 2003 | 12719432 |
| aryl hydrocarbon receptor function in early vertebrates: inducibility of cytochrome p450 1a in agnathan and elasmobranch fish. | the mammalian aryl hydrocarbon receptor (ahr) is a ligand-activated transcription factor that controls the expression of cytochrome p450 1a (cyp1a) genes in response to halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). the natural ligand and normal physiologic function of this protein are as yet unknown. one approach to understanding ahr function and significance is to determine the evolutionary history of this receptor and of processes such as cyp1a induction ... | 1998 | 9827018 |
| excitatory amino acids and serotonin uptake blockers reveal two physiologically distinct serotonin systems in the retina of the skate, raja erinacea. | the retina of the skate (raja erinacea) contains at least 2 types of cell (amacrines and bipolars) that can be visualized with an antiserum against serotonin. we have employed serotonin immunocytochemistry in combination with pharmacological manipulation of retinal tissue to analyze physiological properties of serotonergic amacrine cells and serotonin-accumulating bipolar cells. excitatory amino acids (nmda, aspartate) had no detectable effects on serotonin-immunoreactivity in bipolar cells but ... | 1998 | 9845022 |
| development of dermal denticles in skates (chondrichthyes, batoidea): patterning and cellular differentiation. | patterning, cellular differentiation, and developmental sequences of dermal denticles (denticles) are described for the skate leucoraja erinacea. development of denticles proceeds caudo-rostrally in the tail and trunk. once three rows of denticles form in the tail and trunk, denticles begin to appear in the region of the pelvic girdle, medio-caudal to the eyes and on the pectoral fins. although timing of cellular differentiation of denticles differs among different locations of the body, cellula ... | 1999 | 10398324 |
| light chain variable region diversity in atlantic cod (gadus morhua l.). | this study was undertaken to determine if a lack of v(l) domain variability could explain, in part, the failure of atlantic cod to respond to immunization with the production of specific antibodies. the variability of cod v(l) regions was studied in 33 cdna and two genomic clones. the variability of the cdrs was estimated by the shannon entropy method and compared with that in other species. it was found to be lowest in the little skate (raja erinacea), higher in cod, and highest in xenopus and ... | 1999 | 10402210 |
| reproductive endocrinology of female elasmobranchs: lessons from the little skate (raja erinacea) and spiny dogfish (squalus acanthias). | conventional classification of reproductive modes in female elasmobranchs fails to account for the diversity in ovarian dynamics that operate during oviparous and viviparous cycles. delineating this diversity is crucial for understanding the endocrine regulation of the manifold physiological mechanisms utilized to retain and protect eggs and developing embryos, to fuel embryogenesis, and to manage the intrauterine milieu. oocyte development and follicular steroidogenesis overlap with egg retenti ... | 1999 | 10469994 |
| carrier-mediated uptake of lucifer yellow in skate and rat hepatocytes: a fluid-phase marker revisited. | uptake of lucifer yellow (ly), a fluorescent disulfonic acid anionic dye, was studied in isolated skate (raja erinacea) perfused livers and primary hepatocytes to evaluate its utility as a fluid-phase marker in these cells. however, our findings demonstrated that ly is transported across the plasma membrane of skate hepatocytes largely via carrier-mediated mechanisms. isolated perfused skate livers cleared 50% of the ly from the recirculating perfusate within 1 h of addition of either 22 or 220 ... | 1999 | 10516157 |
| trimethylamine oxide transport across plasma membranes of elasmobranch erythrocytes. | the aim of this study was to characterize the erythrocyte cell membrane transport of trimethylamine oxide (tmao) in the little skate, raja erincea. uptake of tmao occurs by two processes, na(+)-dependent and na(+)-independent. 2,4 dinitrophenol (2,4 dnp), a known atp synthesis inhibitor, inhibited tmao uptake, suggesting the involvement of the na(+)/k(+)-atp pump in na(+)-dependent tmao transport. na(+)-independent tmao uptake was stimulated by cell swelling when erythrocytes were incubated in h ... | 1999 | 10531546 |
| primitive organization of cytosolic ca(2+) signals in hepatocytes from the little skate raja erinacea. | cytosolic ca(2+) (ca(i)(2+)) signals begin as polarized, inositol 1, 4,5-trisphosphate (insp3)-mediated ca(i)(2+) waves in mammalian epithelia, and this signaling pattern directs secretion together with other cell functions. to investigate whether ca(i)(2+) signaling is similarly organized in elasmobranch epithelia, we examined ca(i)(2+) signaling patterns and insp3 receptor (insp3r) expression in hepatocytes isolated from the little skate, raja erinacea. ca(i)(2+) signaling was examined by conf ... | 1999 | 10539953 |
| hepatic toxicity and persistence of ser/thr protein phosphatase inhibition by microcystin in the little skate raja erinacea. | microcystin-induced ser/thr protein phosphatase (pp) inhibition and toxicity were examined in the little skate (raja erinacea), an evolutionarily primitive marine vertebrate. as in mammals, pp inhibition and toxicity were exclusively hepatocellular, but were much more persistent in the skate. a dose of 63 microg/kg given iv to adult male skates resulted in the near complete inhibition of hepatic pp activity at 24 h. pp activity was still 95% inhibited 7 days after dosing in skates given 125 micr ... | 1999 | 10558922 |
| expression of the skate (raja erinacea) ae1 osmolyte channel in xenopus laevis oocytes: monovalent cation permeability. | the aim of this study was to express the cloned skate anion exchanger 1 (skae1) in xenopus oocytes and determine whether the differences in monovalent cation permeabilities in hypotonically stimulated skate and trout erythrocytes could be due to differences in the presence or absence of intracellular channel regulators between the two species or in the intrinsic permeability properties of the channels themselves. the expressed protein (skae1) was inserted into the oocyte cell membrane and facili ... | 2004 | 15209094 |
| osmotic stress stimulates the organic osmolyte channel in xenopus laevis oocytes expressing skate (raja erinacea) ae1. | the aim of this study was to determine whether hypo-osmolarity, which activates taurine transport through the volume-sensitive organic osmolyte channel in skate (raja erinacea) erythrocytes, also activates the organic osmolyte channel activity of skate ae1 (skae1) expressed in oocytes. when xenopus laevis oocytes expressing skae1 were incubated in hypo-osmotic nd 96 (210 mosm) media, taurine was transported at a significantly higher rate than when incubated in nd 96 (235 mosm), which is iso-osmo ... | 2005 | 15776417 |
| immunolocalization of na+/k(+)-atpase in mitochondrion-rich cells of the atlantic hagfish (myxine glutinosa) gill. | using a monoclonal antibody for the alpha-subunit of the na+/k(+)-atpase, daspei (a vital mitochondria dye), and confocal laser scanning microscopy, the presence of na+/k(+)-atpase in mitochondrion-rich cells of the hagfish gill was confirmed. in addition, the level of na+/k(+)-atpase expression in the hagfish gill was compared to that of fishes with different osmoregulatory strategies (little skate, raja erinacea and mummichog, fundulus heteroclitus). immunocytochemistry detected a high density ... | 1999 | 10629957 |
| bile salt excretion in skate liver is mediated by a functional analog of bsep/spgp, the bile salt export pump. | biliary secretion of bile salts in mammals is mediated in part by the liver-specific atp-dependent canalicular membrane protein bsep/spgp, a member of the atp-binding cassette superfamily. we examined whether a similar transport activity exists in the liver of the evolutionarily primitive marine fish raja erinacea, the little skate, which synthesizes mainly sulfated bile alcohols rather than bile salts. western blot analysis of skate liver plasma membranes using antiserum raised against rat live ... | 2000 | 10644562 |
| a primitive atp receptor from the little skate raja erinacea. | p2y atp receptors are widely expressed in mammalian tissues and regulate a broad range of activities. multiple subtypes of p2y receptors have been identified and are distinguished both on a molecular basis and by pharmacologic substrate preference. functional evidence suggests that hepatocytes from the little skate raja erinacea express a primitive p2y atp receptor lacking pharmacologic selectivity, so we cloned and characterized this receptor. skate hepatocyte cdna was amplified with degenerate ... | 2000 | 10900200 |
| phylogeny of anion exchangers: could trout ae1 conductive properties be shared by other members of the gene family? | a phylogenetic tree of anion exchangers (ae) was performed in order to better understand relationships between the different known ae and how they arose. indeed, the different known ae1 from mammals or fish do not exhibit the same transport features: all studied anion exchangers 1 (ae1) catalyse an electroneutral cl-/hco3- exchange through the plasma membrane; however, trout ae1 (tae1) is able to spontaneously form an anion conductive pathway permeable to some inorganic cations (na+ and k+) as w ... | 2005 | 16150548 |
| atp-dependent gsh and glutathione s-conjugate transport in skate liver: role of an mrp functional homologue. | multidrug resistance-associated proteins 1 and 2 (mrp1 and mrp2) are thought to mediate low-affinity atp-dependent transport of reduced glutathione (gsh), but there is as yet no direct evidence for this hypothesis. the present study examined whether livers from the little skate (raja erinacea) express an mrp2 homologue and whether skate liver membrane vesicles exhibit atp-dependent gsh transport activity. antibodies directed against mammalian mrp2-specific epitopes labeled a 180-kda protein band ... | 2000 | 10915652 |
| bile salt export pump is highly conserved during vertebrate evolution and its expression is inhibited by pfic type ii mutations. | bile secretion is a fundamental function of the liver of all vertebrates and is generated by atp-dependent transport proteins at the canalicular membrane of hepatocytes, particularly by the bile salt export pump bsep. to determine the evolutionary origin and structure-function relationship of this transport mechanism, a liver cdna library from the marine skate raja erinacea, a 200 million-year-old vertebrate, was screened for bsep orthologues. a full-length clone was isolated that encodes for 1, ... | 2001 | 11447010 |
| gfap-immunopositive structures in spiny dogfish, squalus acanthias, and little skate, raia erinacea, brains: differences have evolutionary implications. | gfap expression patterns were compared between the brains of a spiny dogfish (squalus acanthias) and a little skate (raia erinacea). after anesthesia, the animals were perfused with paraformaldehyde. serial vibratome sections were immunostained against gfap using the avidin-biotin method. spiny dogfish brain contained mainly uniformly-distributed, radially arranged ependymoglia. from gfap distribution, the layered organization in both the telencephalon and the tectum were visible. in the cerebel ... | 2001 | 11506433 |
| a retrospective of recombinant p2y receptor subtypes and their pharmacology. | since the first cloning of p2y receptor sequences in 1993 it has become apparent that this family of g-protein-coupled receptors is omnipresent. at least 25 individual sequences entered in the genbank sequence database encode p2y receptors from a variety of species ranging from the little skate raja erinacea to man. in man, six receptor subtypes have been cloned and found to be functionally active (p2y(1), p2y(2), p2y(4), p2y(6), p2y(11), and p2y(12)). in this article a review of the p2y recepto ... | 2002 | 11747319 |
| the organic anion transport polypeptide 1d1 (oatp1d1) mediates hepatocellular uptake of phalloidin and microcystin into skate liver. | organic anion transporting polypeptides (rodent oatp; human oatp) mediate cellular uptake of numerous organic compounds including xenobiotic toxins into mammalian hepatocytes. in the little skate leucoraja erinacea a liver-specific oatp (oatp1d1, also called soatp) has been identified and suggested to represent an evolutionarily ancient precursor of the mammalian liver oatp1b1 (human), oatp1b2 (rat), and oatp1b3 (human). the present study tested whether oatp1d1 shares functional transport activi ... | 2007 | 17198718 |
| na+ -d-glucose cotransporter in the kidney of leucoraja erinacea: molecular identification and intrarenal distribution. | studies on membrane vesicles from the kidney of leucoraja erinacea suggested the sole presence of a sodium-d-glucose cotransporter type 1 involved in renal d-glucose reabsorption. for molecular characterization of this transport system, an mrna library was screened with primers directed against conserved regions of human sglt1. a cdna was cloned whose nucleotide and derived amino acid sequence revealed high homology to sodium glucose cotransporter 1 (sglt1). xenopus laevis oocytes injected with ... | 2007 | 17322119 |
| 3,3',4,4'-tetrachlorobiphenyl oxidation in fish, bird and reptile species: relationship to cytochrome p450 1a inactivation and reactive oxygen production. | previously we showed that the polychlorinated biphenyl 3,3',4,4'-tetrachlorobiphenyl (tcb) caused a release of reactive oxygen species (ros) from cytochrome p450 1a (cyp1a) of the fish scup (stenotomus chrysops), and from rat and human cyp1a1. this was linked to a tcb- and nadph-dependent oxidative inactivation of the enzyme, which in scup and rat was inversely related to the rates of tcb oxidation. we examined the relationship between rates of tcb oxidation, cyp1a inactivation and ros productio ... | 2000 | 11790349 |
| immunological detection of na(+)/h(+) exchangers in the gills of a hagfish, myxine glutinosa, an elasmobranch, raja erinacea, and a teleost, fundulus heteroclitus. | na(+)/h(+) exchangers (nhe) are a family of ion exchangers with diverse functions that are well defined in mammals. nhe-1 is expressed in the plasma membrane of most mammalian cells where it regulates intracellular ph, and usually in the basolateral membrane of epithelial cells. it has also been detected in teleost gills where it may participate in systemic ph regulation. nhe-3 is usually expressed in the apical membrane of mammalian epithelial cells where it helps reabsorb na(+) and hco(3)(-); ... | 2002 | 11818226 |
| an evolutionarily ancient oatp: insights into conserved functional domains of these proteins. | cellular uptake of organic solutes is mediated in large part by a gene family of membrane transporters called oatps (slc21a). to study the structural determinants and evolutionary development of the slc21a family, we have cloned and functionally characterized a highly expressed evolutionarily primitive oatp from the liver of the small skate, raja erinacea. a full-length cdna (2.3 kb) was obtained that encodes a protein of 689 amino acids. the characteristics of this novel skate oatp, including t ... | 2002 | 11897630 |
| molecular characterization of a multidrug resistance-associated protein, mrp2, from the little skate. | multidrug resistance protein mrp2 (symbol abcc2) in liver plays a significant role in the biliary excretion of organic anionic conjugates. mutations in human mrp2 result in defects in excretion of conjugated bilirubin and other cholephiles known as the dubin-johnson syndrome. previous studies indicate that transporters with mrp2-like functions are present in ancient vertebrates. we have now characterized an mrp2 ortholog at the molecular level from the liver of the small skate, raja erinacea, a ... | 2003 | 12388433 |
| volume-activated osmolyte channel in skate erythrocytes: inhibition by pyridoxal derivatives. | volume expansion of erythrocytes of little skate, raja erinacea, triggers the opening of an osmolyte channel. we review this transport mechanism and further investigate the channel's physicochemical nature by probing the channel with a series of pyridoxine derivatives in skate rbc as well as in epithelial cells: mdck and c6 glioma cells and in skate hepatocytes. the identity of the transport mechanism (band 3 vs. an anion channel) which mediates the swelling-activated efflux of osmolytes in fish ... | 1997 | 9392866 |
| characterization of progesterone-binding moieties in the little skate raja erinacea. | in this study we report evidence of a [3h]progesterone-binding moiety in the liver and oviduct of the little skate raja erinacea. it is characterized by high affinity, low capacity and dna-cellulose-binding activity. furthermore western blot analysis revealed that monoclonal antibodies against the chicken progesterone receptor (pr) subunits a and b cross-reacted with a 110-kda band in the liver and a 80-kda band in the oviduct. when analyzed by deae-sepharose ion-exchange column chromatography, ... | 1998 | 9446728 |
| localization and partial characterization of melatonin receptors in amphioxus, hagfish, lamprey, and skate. | through its secretion of melatonin, the pineal complex of vertebrates exerts a range of physiological effects including regulation of circadian rhythms, seasonal reproduction, metamorphosis, and body color change. little is known about phylogenetic differences in the distribution and characteristics of melatonin binding sites in fishes. we used in vitro autoradiography to examine binding of [2-125i]iodomelatonin (imel) in 20-micron frozen sections of amphioxus (branchiostoma lanceolatum), atlant ... | 1998 | 9514841 |
| the central vessel of the renal countercurrent bundles of two marine elasmobranchs--dogfish (scyliorhinus caniculus) and skate (raja erinacea)--as revealed by light and electron microscopy with computer-assisted reconstruction. | the renal countercurrent bundles of elasmobranch fish were studied by light and electron microscopy. the kidneys of the lesser spotted dogfish, scyliorhinus caniculus blainville, and the little skate, raja erinacea mitchill, were investigated. three-dimensional reconstruction with computer assistance revealed the spatial association of the renal tubular segments and their relationships to each other, as well as to the microvasculature. regular association between structures was assessed by quant ... | 1998 | 9683069 |
| endogenous zinc as a retinal neuromodulator: evidence from the skate (raja erinacea). | the effects of zinc on skate (raja erinacea) bipolar cell responses to glutamatergic agonists were examined using whole-cell voltage-clamp recording. isolated on bipolar cell currents mediated by the metabotropic agonist trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid (30 microm), l-2-amino-4-phosphonobutyrate (3-10 microm) and glutamate (0.3-10 microm) were blocked when zinc (1 microm) was added to the test solution. similarly, isolated off bipolar cell responses to the ionotropic agonist ... | 2003 | 12821176 |
| copper homeostasis and toxicity in the elasmobranch raja erinacea and the teleost myoxocephalus octodecemspinosus during exposure to elevated water-borne copper. | clear nosed skate, raja erinacea were exposed to 0.10 (control), 0.52 or 1.73 microm copper and sculpin, myoxocephalus octodecemspinosus were exposed to 0.10 or 1.73 microm copper (as cuso4) in salisbury cove seawater for up to seven days. skate gill copper concentrations increased 40-50 fold over background in response to copper exposure at both concentrations. in comparison, sculpin gill levels only increased 3-fold. while there was no evidence for internalized copper in the skate arising from ... | 2003 | 12860057 |
| regulation of a renal urea transporter with reduced salinity in a marine elasmobranch, raja erinacea. | marine elasmobranchs retain urea and other osmolytes, e.g. trimethylamine oxide (tmao), to counterbalance the osmotic pressure of seawater. we investigated whether a renal urea transporter(s) would be regulated in response to dilution of the external environment. a 779 bp cdna for a putative skate kidney urea transporter (skut) was cloned, sequenced and found to display relatively high identity with facilitated urea transporters from other vertebrates. northern analysis using skut as a probe rev ... | 2003 | 12909709 |
| urea transport in kidney brush-border membrane vesicles from an elasmobranch, raja erinacea. | marine elasmobranch fishes maintain high urea concentrations and therefore must minimize urea loss to the environment in order to reduce the energetic costs of urea production. previous studies have identified a facilitated urea transporter in the kidney of the dogfish. we examined mechanisms of urea transport in the kidney of the little skate raja erinacea using an isolated brush-border membrane vesicle preparation. urea uptake by brush-border membrane vesicles is by a phloretin-sensitive, non- ... | 2003 | 12909710 |
| in vitro effect of mammalian adrenocorticotropin on secretion of skate (raja erinacea) interrenal tissue. | | 1962 | 14467760 |
| lack of biliary lipid excretion in the little skate, raja erinacea, indicates the absence of functional mdr2, abcg5, and abcg8 transporters. | the abc transporters bile salt export pump (bsep; encoded by the abcb11 gene), mdr3 p-glycoprotein (abcb4), and sterolin 1 and 2 (abcg5 and abcg8) are crucial for the excretion of bile salt, phospholipid, and cholesterol, respectively, into the bile of mammals. the current paradigm is that phospholipid excretion mainly serves to protect membranes of the biliary tree against bile salt micelles. bile salt composition and cytotoxicity, however, differ greatly between species. we investigated whethe ... | 2004 | 14701720 |
| the anion exchanger as an osmolyte channel in the skate erythrocyte. | regulatory volume decrease occurs in fish erythrocytes by the release of osmolytes via a channel involving the anion exchanger (ae), also known as band 3. this review focuses primarily on work done on red blood cells from the skate (raja erinacea) to further understand the activation, regulation and identification of this osmolyte channel. a model is proposed in which the reduction in intracellular ionic strength that occurs with increased cell volume may change the interaction between ae dimers ... | 2004 | 14992261 |
| dogmas and controversies in the handling of nitrogenous wastes: osmoregulation during early embryonic development in the marine little skate raja erinacea; response to changes in external salinity. | marine elasmobranchs retain relatively high levels of urea to counterbalance the osmotic strength of seawater. oviparous species, such as the little skate raja erinacea, release encapsulated embryos that hatch after about 9 months on the seafloor. to study the ureosmotic capability of skate embryos, we measured a variety of possible osmolytes and ornithine-urea cycle (ouc) enzyme activities in little skate embryos, and determined their physiological response to dilute seawater (75% sw) exposure ... | 2004 | 15143136 |
| the little skate raja erinacea exhibits an extrahepatic ornithine urea cycle in the muscle and modulates nitrogen metabolism during low-salinity challenge. | urea synthesis via the hepatic ornithine urea cycle (ouc) has been well described in elasmobranchs, but it is unknown whether ouc enzymes are also present in extrahepatic tissues. muscle and liver urea, trimethylamine oxide (tmao), and other organic osmolytes, as well as selected ouc enzymes (carbamoyl phosphate synthetase iii, ornithine transcarbamoylase, arginase, and the accessory enzyme glutamine synthetase), were measured in adult little skates (raja erinacea) exposed to 100% or 75% seawate ... | 2005 | 15778941 |
| cloning, immunolocalization, and functional expression of a gaba transporter from the retina of the skate. | termination of gaba signals within the retina occurs through high-affinity reuptake of the released neurotransmitter by gaba transporters (gats) present in neurons and glia surrounding the release site. in the present work, we have cloned a novel gat from the retina of the skate (raja erinacea). the clone codes for a 622 amino acid protein whose sequence has highest similarity to the gaba/beta-alanine transporter of the electric ray (torpedo marmorata) (88% identity) and the gat-3 isolated from ... | 2005 | 15935113 |
| novel non-rodent models of kidney disease. | kidney disease in the 21(st) century affects increasing numbers of individuals. we continue to be challenged by our lack of understanding of the pathophysiology of acute and chronic renal disease including genetic diseases involving the kidney. rodent knockout animals or inbred strains have greatly contributed to our understanding of many monogenetic and complex diseases. non-rodent animal models of disease have become more attractive since genomic data has become available for a variety of orga ... | 2005 | 16101482 |
| retention of structural and functional polarity in cultured skate hepatocytes undergoing in vitro morphogenesis. | the present study characterized a primary culture model of hepatocytes isolated from the little skate, leucoraja erinacea, that maintain remarkable structural and functional polarity over 7 days in culture. skate hepatocytes were isolated as clusters of 3-20 hepatocytes surrounding a bile canaliculus, rather than as single cells. trypan blue and propidium iodide exclusion was found to be >98%, and the cells maintained high intracellular concentrations of k+, atp, and reduced glutathione (gsh), a ... | 2006 | 16567119 |
| membrane trafficking factors are involved in the hypotonic activation of the taurine channel in the little skate (raja erinacea) red blood cell. | in response to volume expansion, red blood cells of the little skate (raja erinacea) initially swell and then release small organic compounds and osmotically obligated water in what is called a regulatory volume decrease (rvd) to restore cell volume. one of the major intracellular solutes lost during this process is the non-metabolized beta amino acid taurine. this hypoosmotic-induced increase in cell taurine permeability requires the anion exchanger, skae1. the abundance of this transporter inc ... | 2006 | 16615100 |
| cell membrane surface expression and tyrosine kinase regulate the osmolyte channel (skae1) in skate erythrocytes. | a regulatory volume decrease response occurs when skate (raja erinacea) erythrocytes are exposed to hyposmotic medium; they swell and then reduce their volume by releasing organic osmolytes (primarily taurine) and associated water. the response involves the red blood cell anion-exchanger skate anion-exchanger 1 (skae1), which has been previously shown to be affected by tyrosine phosphorylation, to form tetramers and to change binding affinities to the cytoskeletal proteins, ankyrin and band 4.1. ... | 2006 | 16734745 |
| cell and molecular biology of sae, a cell line from the spiny dogfish shark, squalus acanthias. | cartilaginous fish, primarily sharks, rays and skates (elasmobranchs), appeared 450 million years ago. they are the most primitive vertebrates, exhibiting jaws and teeth, adaptive immunity, a pressurized circulatory system, thymus, spleen, and a liver comparable to that of humans. the most used elasmobranch in biomedical research is the spiny dogfish shark, squalus acanthias. comparative genomic analysis of the dogfish shark, the little skate (leucoraja erincea), and other elasmobranchs have yie ... | 2007 | 16949345 |
| establishment of the onset of host specificity in four phyllobothriid tapeworm species (cestoda: tetraphyllidea) using a molecular approach. | a parasitological survey in the bay of fundy, canada, resulted in the recovery of mature specimens from 5 species of phyllobothriid tapeworms (cestoda: tetraphyllidea) from 4 rajid skates: echeneibothrium canadensis and e. dubium abyssorum specimens from amblyraja radiata; e. vernetae and pseudanthobothrium n.sp. from leucoraja erinacea and l. ocellata; and p. hanseni from a. radiata and malacoraja senta. partial sequence data of a variable region (d2) from the large subunit ribosomal dna (lsu) ... | 2007 | 17462121 |
| influence of reproductive activity, sex steroids, and seasonality on epigonal organ cellular proliferation in the skate (leucoraja erinacea). | in elasmobranchs, the epigonal organ, a unique leukopoietic immune tissue, is associated with the gonads. as the ovaries increase in size during reproductive activity, the overall mass of the epigonal organ does not change. however, immunohistochemistry (proliferating cell nuclear antigen ab) demonstrated more proliferative activity and extravasation of epigonal leukocytes from blood vessels in reproductively active (ra) skates (leucoraja erinacea) than in non-reproductively active (nra) skates. ... | 2008 | 17499739 |
| comparison of acid mucin goblet cell distribution and hox13 expression patterns in the developing vertebrate digestive tract. | the digestive tract of vertebrates is a complex organ system required for the digestion of food and the absorption of nutrients. the colon evolved as a water absorption organ essential for vertebrates to survive on land. in contrast to land vertebrates, the chondrichthyes (sharks, skates and rays) are nearly iso-osmotic with their ocean environment and do not reabsorb water from food waste. to understand the origin of the vertebrate colon, we examined the distribution of sulfated and sialyated m ... | 2007 | 17538949 |
| the farnesoid x receptor fxralpha/nr1h4 acquired ligand specificity for bile salts late in vertebrate evolution. | the nuclear receptor fxralpha (nr1h4) plays a pivotal role in maintaining bile salt and lipid homeostasis by functioning as a bile salt sensor in mammals. in contrast, fxrbeta (nr1h5) from mouse is activated by lanosterol and does not share common ligands with fxralpha. to further elucidate fxr ligand/receptor and structure/function relationships, we characterized a fxr gene from the marine skate, leucoraja erinacea, representing a vertebrate lineage that diverged over 400 million years ago. phy ... | 2007 | 17567710 |
| effects of reproductive activity and sex hormones on apoptosis in the epigonal organ of the skate (leucoraja erinacea). | in elasmobranchs, a unique association exists between an immune tissue, the epigonal organ, and the gonads. the intimate morphological relationship between these tissues suggests functional interactions. in this study, we used apoptosis to assess differences between epigonal tissues of reproductively active (ra) and non-reproductively active (nra) skates (leucoraja erinacea). plasma steroid levels were significantly higher in ra than in nra animals, and tunel analysis showed that epigonal tissue ... | 2007 | 17714713 |
| nephrogenesis is induced by partial nephrectomy in the elasmobranch leucoraja erinacea. | the mammalian kidney responds to partial nephrectomy with glomerular and tubular hypertrophy, but without renal regeneration. in contrast, renal regeneration in lower vertebrates is known to occur. understanding the underlying mechanisms of renal regeneration is highly important; however, a serviceable animal model has not been developed. a neonephrogenic zone has been identified in the european lesser spotted dogfish, scyliorhinus caniculus (hentschel h. am j anat 190: 309-333, 1991), as well a ... | 2003 | 12761251 |
| notes on the atrophy of the eye of raja erinacea. | | 1908 | 17740081 |
| cell and molecular biology of marine elasmobranchs: squalus acanthias and raja erinacea. | elasmobranchs are among the most primitive existing species exhibiting fundamental vertebrate characteristics, such as neural crest, jaws, teeth, and an adaptive immune system. they are also among the earliest-evolved vertebrates with a closed, pressurized circulatory system and related signaling molecules. although many species are used experimentally, the spiny dogfish shark (squalus acanthias) and little skate (raja erinacea) have particular advantages and are the most commonly used elasmobra ... | 2004 | 18248223 |
| carrier-mediated urea transport across the mitochondrial membrane of an elasmobranch (raja erinacea) and a teleost (oncorhynchus mykiss) fish. | in osmoregulating teleost fish, urea is a minor nitrogen excretory product, whereas in osmoconforming marine elasmobranchs it serves as the major tissue organic solute and is retained at relatively high concentrations ( approximately 400 mmol/l). we tested the hypothesis that urea transport across liver mitochondria is carrier mediated in both teleost and elasmobranch fishes. intact liver mitochondria in rainbow trout (oncorhynchus mykiss) demonstrated two components of urea uptake, a linear com ... | 2008 | 18385468 |
| arachidonic acid-induced expression of the organic solute and steroid transporter-beta (ost-beta) in a cartilaginous fish cell line. | the organic solute and steroid transporter (ost/ost) is a unique membrane transport protein heterodimer composed of subunits designated alpha and beta, that transports conjugated steroids and prostaglandin e(2) across the plasma membrane. ost was first identified in the liver of the cartilaginous fish leucoraja erinacea, the little skate, and subsequently was found in many other species, including humans and rodents. the present study describes the isolation of a new cell line, lee-1, derived fr ... | 2008 | 18407792 |
| an improved method for separation of leucocytes from peripheral blood of the little skate (leucoraja erinacea). | cartilaginous fish, especially sharks, rays and skates (elasmobranchs), hold interest as comparative models in immunology because they are thought to be among the organisms most closely related to the ancestor animal that first developed acquired immunity. the aim of this study was to improve methods used for the purification of viable leucocytes from peripheral blood of elasmobranchs. here we describe modifications of density gradient centrifugation and medium formulation that improve isolation ... | 2008 | 18474431 |
| purification, structural characterization, and myotropic activity of a peptide related to des-arg(9)-bradykinin from an elasmobranch fish, the little skate, leucoraja erinacea. | a bradykinin (bk)-related peptide was isolated from heat-denaturated plasma from an elasmobranch fish, the little skate, leucoraja erinacea after incubation with porcine pancreatic kallikrein. the primary structure of the peptide (h-gly-ile-thr-ser-trp-leu-pro-phe-oh; skate bk) shows limited structural similarity to the mammalian b1 receptor agonist, des-arg(9)-bk. the myotropic activities of synthetic skate bk, and the analog skate [arg(9)]bk, were examined in isolated skate vascular and intest ... | 2008 | 18502540 |
| determinants of host specificity and comments on attachment site specificity of tetraphyllidean cestodes infecting rajid skates from the northwest atlantic. | the objectives of this study were to (1) describe the host range for 6 tetraphyllidean species and quantify their host specificity using 5 specificity indices; (2) determine the role of morphological determinants in the host specificity of tetraphyllideans by comparing villar and bothridial measurements of species examined herein; and (3) determine the role of a physiological component in the host specificity of tetraphyllideans by exposing tetraphyllideans to blood sera from different fish spec ... | 2008 | 18564745 |
| evolution of hormone signaling in elasmobranchs by exploitation of promiscuous receptors. | specific interactions among proteins, nucleic acids, and metabolites drive virtually all cellular functions and underlie phenotypic complexity and diversity. despite the fundamental importance of interactions, the mechanisms and dynamics by which they evolve are poorly understood. here we describe novel interactions between a lineage-specific hormone and its receptors in elasmobranchs, a subclass of cartilaginous fishes, and infer how these associations evolved using phylogenetic and protein str ... | 2008 | 18799714 |
| marine organism cell biology and regulatory sequence discoveryin comparative functional genomics. | the use of bioinformatics to integrate phenotypic and genomic data from mammalian models is well established as a means of understanding human biology and disease. beyond direct biomedical applications of these approaches in predicting structure-function relationships between coding sequences and protein activities, comparative studies also promote understanding of molecular evolution and the relationship between genomic sequence and morphological and physiological specialization. recently recog ... | 2005 | 19003267 |
| plasma levels of nitrite and nitrate in early and recent classes of fish. | the stable metabolite of nitric oxide in plasma is nox, the sum of nitrite plus nitrate. measures of plasma nox may provide information about the nitric oxide tonus of the entire endothelium including capillary microvessels. although data are available for mammalian species, plasma nox measurements in early vertebrate species are scarce. the purpose of this study was to test the hypothesis that plasma nox would be similar to the no in the water environment for fish in early classes (agnatha and ... | 2008 | 19004368 |
| plasticity in a cerebellar-like structure: suppressing reafference during episodic behaviors. | detection of relevant sensory signals requires the filtering out of irrelevant noise, including noise created by the animal's own movements (reafference). this is accomplished in the electrosense of little skates (raja erinacea) by an adaptive filter in the cerebellar-like electrosensory nucleus (dorsal nucleus) in the medulla. we have shown that electrosensory inputs reliably coupled to the regularly recurring movements of breathing over time are eliminated selectively in the principal neurons ... | 2008 | 19011212 |
| identification of angiotensinogen genes with unique and variable angiotensin sequences in chondrichthyans. | the renin-angiotensin system is an enzyme-linked hormonal cascade that plays an important role in body fluid and cardiovascular regulation. the system is initiated by the action of renin on the precursor protein, angiotensinogen (agt), whose sequence information is scarce because of its high variability among species. in the present study, we cloned agt in chondrichthyans (elasmobranchs: triakis scyllium, dasyatis akajei,leucoraja erinacea and a holocephalan: callorhinchus milii). homology was l ... | 2009 | 19071126 |
| chondrogenesis and homology of the visceral skeleton in the little skate, leucoraja erinacea (chondrichthyes: batoidea). | chondrichthyan fishes possess visceral skeletons that differ considerably, morphologically, from those of their sister taxon, the osteichthyans. here, we use histological techniques and whole-mount skeletal preparations to visualize and describe the sequence of visceral skeletal condensation and chondrogenesis in a chondrichthyan, the little skate (leucoraja erinacea). we demonstrate that visceral skeletal condensation begins rostrally, with the mandibular arch, and progresses caudally with the ... | 2009 | 19117064 |
| hepatic uptake and biliary excretion of manganese in the little skate, leucoraja erinacea. | the liver is a major organ involved in regulating whole body manganese (mn) homeostasis; however, the mechanisms of mn transport across the hepatocyte basolateral and canalicular membranes remain poorly defined. to gain insight into these transport steps, the present study measured hepatic uptake and biliary excretion of mn in an evolutionarily primitive marine vertebrate, the elasmobranch leucoraja erinacea, the little skate. mn was rapidly removed from the recirculating perfusate of isolated p ... | 2009 | 19141331 |
| comparative genomics of chondrichthyan hoxa clusters. | the chondrichthyan or cartilaginous fish (chimeras, sharks, skates and rays) occupy an important phylogenetic position as the sister group to all other jawed vertebrates and as an early lineage to diverge from the vertebrate lineage following two whole genome duplication events in vertebrate evolution. there have been few comparative genomic analyses incorporating data from chondrichthyan fish and none comparing genomic information from within the group. we have sequenced the complete hoxa clust ... | 2009 | 19725973 |
| gastro-intestinal handling of water and solutes in three species of elasmobranch fish, the white-spotted bamboo shark, chiloscyllium plagiosum, little skate, leucoraja erinacea and the clear nose skate raja eglanteria. | the present study reports aspects of gi tract physiology in the white-spotted bamboo shark, chiloscyllium plagiosum, little skate, leucoraja erinacea and the clear nose skate, raja eglanteria. plasma and stomach fluid osmolality and solute values were comparable between species, and stomach ph was low in all species (2.2 to 3.4) suggesting these elasmobranchs may maintain a consistently low stomach ph. intestinal osmolality, ph and ion values were comparable between species, however, some differ ... | 2010 | 19782760 |
| organic solute transporter, ostalpha-ostbeta: its role in bile acid transport and cholestasis. | organic solute transporter alpha-beta (ostalpha-ostbeta) is a unique heteromeric transporter localized to the basolateral membrane of epithelial cells involved in sterol transport. it is believed to be the primary bile acid efflux transporter in the intestine of mammals and is therefore essential to bile acid homeostasis and the enterohepatic circulation. first described in the evolutionarily primitive small skate, leucoraja erinacea, this facilitated transporter requires expression of both subu ... | 2010 | 20422499 |
| analysis and functional annotation of expressed sequence tags from in vitro cell lines of elasmobranchs: spiny dogfish shark (squalus acanthias) and little skate (leucoraja erinacea). | elasmobranchs are the most commonly used experimental models among the jawed, cartilaginous fish (chondrichthyes). previously we developed cell lines from embryos of two elasmobranchs, squalus acanthias the spiny dogfish shark (sae line), and leucoraja erinacea the little skate (lee-1 line). from these lines cdna libraries were derived and expressed sequence tags (ests) generated. from the sae cell line 4303 unique transcripts were identified, with 1848 of these representing unknown sequences (s ... | 2010 | 20471924 |
| the importance of n-methyl-d-aspartate (nmda) receptors in subtraction of electrosensory reafference in the dorsal nucleus of skates. | the dorsal nucleus of the little skate is a cerebellum-like sensory structure that adaptively filters out predictable electrosensory inputs. the filter's plasticity is mediated by anti-hebbian associative depression at the synapses between parallel fibers and ascending efferent neurons (aens). changes in synaptic strength are indicated by the formation of a cancellation signal which is initiated by co-activation of parallel fibers and aens, and can be reversed by parallel fiber activity in the a ... | 2010 | 20639432 |
| reproductive characteristics and population decline of four species of skate (rajidae) off the eastern coast of canada. | four of the most common species of skate (rajidae) were studied off eastern canada to determine if their reproductive characteristics were linked to their population trajectories. the fecundity of the winter skate leucoraja ocellata, the little skate leucoraja erinacea, the thorny skate amblyraja radiata and the smooth skate malacoraja senta averaged between 41 and 56 egg cases per year for each species. for all species but l. ocellata, males matured at larger sizes and at later ages than female ... | 2009 | 20738493 |
| size and age estimates at sexual maturity for the little skate leucoraja erinacea from the western gulf of maine, u.s.a. | size and age estimates at sexual maturity were determined for 162 male and 273 female little skates leucoraja erinacea collected from the western gulf of maine. maturity ogives suggest that 50% maturity in females occurs at age 9.5 years and 480 mm total length (lt), whereas 50% maturity in males occurs at a slightly younger age of 7.7 years and smaller size of 460 mm lt. age estimates were made from 389 l. erinacea ranging in size from 93 to 570 mm lt. the index of average per cent error and ag ... | 2009 | 20738640 |
| an investigation on the effect of photoperiod and temperature on vertebral band deposition in little skate leucoraja erinacea. | an investigation was undertaken to determine whether photoperiod or temperature have an effect on the timing of vertebral opaque-transluscent band-pair deposition in captive young-of-the-year (yoy) little skate leucoraja erinacea. the experimental design consisted of a randomized complete block split plot design with two factors: temperature and light. temperature was nested within light and therefore four variables were tested: 1) constant light, 2) constant temperature, 3) seasonal light and 4 ... | 2010 | 20840621 |
| morphological relationships and leukocyte influence on steroid production in the epigonal organ-ovary complex of the skate, leucoraja erinacea. | in elasmobranchs, a unique association exists between an immune tissue, the epigonal organ (eo), and the gonads. in this study, the histological and vascular relationships of the eo and ovarian follicles of the little skate, leucoraja erinacea, were assessed. perfusions of evans blue dye and batson's monomer showed a shared vascular pathway from the gonadal artery into the epigonal-ovary complex, with blood first entering the eo and then perfusing the ovarian follicles. histological studies demo ... | 2008 | 18302243 |
| redescription of pseudanthobothrium hanseni baer, 1956 and description of p. purtoni n. sp. (cestoda: tetraphyllidea) from different pairs of rajid skate hosts, with comments on the host-specificity of the genus in the northwest atlantic. | during a parasitological survey of leucoraja erinacea, l. ocellata, malacoraja senta and amblyraja radiata from passamaquoddy bay and waters surrounding the west isles of the bay of fundy, nb, canada, seven species of cestodes were recovered. examination of these skates revealed the presence of two distinct species of pseudanthobothrium baer, 1956: one was retrieved from m. senta and a. radiata, identified as p. hanseni baer, 1956 and redescribed herein; the other was retrieved from l. erinacea ... | 2008 | 18373219 |
| seasonal variations in the physiological stress response to discrete bouts of aerial exposure in the little skate, leucoraja erinacea. | aerial exposure and acute thermal stress have been shown to elicit profound physiological disruptions in obligate water-breathing teleosts. however, no study has investigated these responses in an elasmobranch. to address this, venous blood samples were collected and evaluated from little skates (leucoraja erinacea) subjected to discrete aerial exposure durations (0, 15, and 50min) coupled with differing abrupt thermal changes (gradient between seawater and air; winter: +öt=-3-¦c; summer: +öt=+9 ... | 2011 | 21689777 |
| cardiovascular and vasoconstrictive actions of skate bradykinin in the little skate, leucoraja erinacea (elasmobranchii). | the vasoconstrictive and cardiovascular actions of a recently identified bradykinin (bk)-related peptide (gly-ile-thr-ser-trp-leu-pro-phe) from the little skate, leucoraja erinacea were examined in the unanesthetised little skate. intra-arterial administration of a skate bk (0.1-1 nmolkg(-1)) produced a hypertensive response with a rise in blood pressure reaching a maximum elevation of 28.7±4.8% over baseline (p<0.05, n=8) that was sustained for at least 12 min following administration of a 1 an ... | 2011 | 21893060 |
| body fluid osmolytes and urea and ammonia flux in the colon of two chondrichthyan fishes, the ratfish, hydrolagus colliei, and spiny dogfish, squalus acanthias. | the present study has examined the role of the colon in regulating ammonia and urea nitrogen balance in two species of chondrichthyans, the ratfish, hydrolagus colliei (a holocephalan) and the spiny dogfish, squalus acanthias (an elasmobranch). stripped colonic tissue from both the dogfish and ratfish was mounted in an ussing chamber and in both species bi-directional urea flux was found to be negligible. urea uptake by the mucosa and serosa of the isolated colonic epithelium through accumulatio ... | 2012 | 21911071 |
| expression of vitellogenin receptor in the ovarian follicles during the reproductive cycle of the spotted ray torpedo marmorata risso 1880. | the aim of this investigation was to identify the encoding sequence of vitellogenin receptor gene (vtgr), and its expression during the oogenesis in the spotted ray, torpedo marmorata, in different phases of reproductive cycle. from an ovarian cdna of vitellogenic female, we obtained a fragment of 581 bp, which corresponds to a partial sequence encoding the vitellogenin receptor (vtgr) in torpedo (accession number: gi/193244760). this sequence shows a high identity with the vtgr of other vertebr ... | 2011 | 22021242 |