| cholinergic amacrine neurons of the dogfish retina. | in the mammalian retina, the dendritic arbors of cholinergic amacrine neurons have a unique starburst shape; these arbors lie in narrow sublaminae within the inner plexiform layer, where they provide input to a wide variety of ganglion cell types. immunocytochemistry has been used to identify cholinergic cells in one poikilotherm, the goldfish (tumosa et al., 1984), but there has been no description of the detailed dendritic morphology of these cells in the lower vertebrates. in the present stud ... | 1991 | 1883761 |
| elasmobranch vision: multimodal integration in the brain. | multimodal sensory areas that include vision have been identified physiologically in two separate pallial areas in the telencephalon and in the tectum of the mesencephalon. multisensory integration occurs in the medial pallium of the little skate, raja erinacea, and a primitive squalomorph shark, squalus acanthias, whereas in the advanced galeomorph shark, ginglymostoma cirratum, a major multimodal area is in the dorsal pallium pars centralis. pars centralis has undergone extensive hypertrophy i ... | 1990 | 1982491 |
| partial amino acid sequence of erythrocyte carbonic anhydrase from tiger shark. | 1. a partial primary structure (197 residues) of carbonic anhydrase from tiger shark (galeocerdo cuvieri) erythrocytes has been determined. 2. the amino acid sequence of the enzyme is identical to those of human cytoplasmic carbonic anhydrases (ca i-iii) by as much as 52-60%. 3. it is shown that tiger shark ca most closely resembles the ca ii isoenzyme of amniotes. 4. isoelectric focusing and inhibition studies on carbonic anhydrase from dogfish (squalus acanthias) blood and muscle indicate the ... | 1990 | 2110050 |
| the presence of a juxtaglomerular apparatus in elasmobranch fish. | previous studies have concluded that a juxtaglomerular apparatus evolved in phylogenetic groups "higher" than elasmobranch fishes. the present study shows for the first time a distinct juxtaglomerular apparatus in four marine elasmobranchs, the spiny dogfish squalus acanthias), the smooth dogfish (mustelus canis), the little skate (raja erinacea), and the cownose ray (rhinoptera bonasus). serial semithin sections of these fishes' kidneys reveal the four morphological components of a juxtaglomeru ... | 1990 | 2268068 |
| [anatomical study on the facial nerve innervating the floor of the mouth in chondrichthyes. homology of the chorda tympani]. | this paper deals with the results of the investigation of the facial nerves of chondrichthyes in order to consider the phylogenetic origin of the chorda tympani in human. six species of elasmobranchs (chlamydoselachus anguineus, cephaloscyllium umbratile, squalus acanthias, dasyatis akajei, raja kwangtungensis and mobura diabolus) were dissected under a stereoscopic microscope for this purpose, and the following results were obtained. ramus palatinus and r. pre-spiracularis were observed as pre- ... | 1989 | 2489341 |
| granulated peripolar epithelial cells in the renal corpuscle of marine elasmobranch fish. | granulated epithelial cells at the vascular pole of the renal corpuscle, peripolar cells, have been found in the kidneys of five species of elasmobranchs, the little skate (raja erinacea), the smooth dogfish shark (mustelus canis), the atlantic sharpnose shark (rhizoprionodon terraenovae), the scalloped hammerhead shark (sphyrna lewini), and the cow-nosed ray (rhinoptera bonasus). in a sixth elasmobranch, the spiny dogfish shark (squalus acanthias), the peripolar cells could not be identified am ... | 1989 | 2519933 |
| neuronal localization of immunoreactive adrenocorticotropin-like substance in the hypothalamus of elasmobranch fishes. | the occurrence and localization of adrenocorticotropin (acth)-like material in the brain of two species of elasmobranch fishes, scyliorhinus canicula and squalus acanthias, were studied by immunohistochemical techniques using an antiserum generated against human acth1-24. in both species immunopositive neurons and fibers were recognized in the basal hypothalamus mainly distributed in the nucleus lateralis tuberis, in which many of these elements were of the liquor-contacting type. a few acth-lik ... | 1987 | 2821456 |
| retinal neurochemistry of three elasmobranch species: an immunohistochemical approach. | we surveyed retinas of raja erinacea, mustelus canis, and squalus acanthias for neurotransmitter substances by using antisera directed against the substances themselves or against their synthesizing enzymes. both the peroxidase-antiperoxidase (pap) and indirect fluorescent techniques were employed to visualize the primary antisera. in all three species positive results were obtained with antisera directed against tyrosine hydroxylase (toh), glutamic acid decarboxylase (gad), serotonin (5-ht), an ... | 1986 | 2869065 |
| electronmicroscopical, immunohistochemical, immunocytochemical and biological evidence for the occurrence of cardiac hormones (anp/cdd) in chondrichthyes. | as representatives of the vertebrate class of chondrichthyes the plagostomian species squalus acanthias, scyliorhinus canicula and raja clavata as well as the holocephalan species chimaera monstrosa were investigated for the presence of cardiac hormones of the atrial natriuretic polypeptide/cardiodilatin- (anp/cdd-) family. anp/cdd-immunoreactive cells were detected in the atria and the ventricles of all species studied. while these cells failed to react with antisera raised against the n-termin ... | 1987 | 2961715 |
| atrial natriuretic peptide stimulates salt secretion by shark rectal gland by releasing vip. | salt secretion by the isolated perfused rectal gland of the spiny dogfish shark, squalus acanthias, is stimulated by synthetic rat atrial natriuretic peptide (anp ii) as well as extracts of shark heart, but not by 8-bromo-cyclic guanosine 5'-monophosphate. cardiac peptides have no effect on isolated rectal gland cells or perfused tubules, suggesting that stimulation requires an intact gland. the stimulation of secretion by anp ii is eliminated by maneuvers that block neurotransmitter release. th ... | 1987 | 3028157 |
| elasmobranch tissue culture: in vitro growth of brain explants from a shark (rhizoprionodon) and dogfish (squalus). | brain explants from a caribbean sharpnose shark (rhizoprionodon porosus) and six spiny dogfish (squalus acanthias) were cultured at 22 degrees c in leibovitz l-15 medium, 1000 mosmol, with 350 mm urea, 20 mm added nacl, and either 2% fetal bovine serum, 2% bull shark (carcharhinus leucas) serum, or 2% spiny dogfish serum. cell outgrowth from explants appeared after 1 month. cells were subcultured once with 20% survival, and were viable at termination of the trials 6 months later. cell morphology ... | 1988 | 3232143 |
| dogfish alpha-crystallin sequences. comparison with small heat shock proteins and schistosoma egg antigen. | the amino acid sequences of the alpha-crystallin a and b chains of the dogfish, squalus acanthias, have been determined. comparison with alpha-crystallins from other species reveals that charged amino acid replacements have been strongly avoided in the evolution of this lens protein. the homology of alpha-crystallins with the small heat shock proteins is pronounced throughout the major part of the proteins, starting from the position of the first intron in the alpha-crystallin genes, but is also ... | 1988 | 3356684 |
| a comparison of dogfish and porcine pancreatic lipases. | 1. a 16-fold purification of lipase activity from the pancreas of the dogfish (squalus acanthias) was obtained by preparative isoelectric focussing. 2. the dogfish enzyme has a higher ph optimum (8.5) and a broader spectrum of activity above and below its optimum than a commercial porcine lipase preparation (optimum, 7.5). 3. the temperature optimum of dogfish lipase was 35 degrees c and it displayed greater stability than the porcine lipase preparation towards higher temperatures in the absence ... | 1988 | 3378405 |
| a novel ganglioside in dogfish brain. occurrence of a trisialoganglioside with a sialic acid linked to n-acetylgalactosamine. | a novel trisialoganglioside has been isolated from dogfish (squalus acanthias) brain. from the results of gas chromatography-mass spectrometric analysis of methylated sugars, enzymatic hydrolysis, fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance analysis, its structure was concluded to be (formula; see text) this is the first report of the occurrence of a ganglioside with 3 sialic acid residues separately linked to its gangliotetraosyl backbone. | 1988 | 3384822 |
| a comparison of dogfish and bovine chymotrypsins. | bovine and dogfish chymotrypsins were compared to determine if chymotrypsin from a poikilothermic organism (spiny dogfish (squalus acanthias] adapted to low temperatures possessed catalytic properties different from those of the same enzyme from a warm-blooded animal. an improved procedure was developed for isolating dogfish pancreatic chymotrypsin. the least hydrophobic and smallest substrate used, p-nitrophenyl acetate, had similar enthalpies of association (delta ha) with both enzymes, wherea ... | 1987 | 3606118 |
| some kinetic properties of dogfish chymotrypsin. | a comparison of some kinetic properties was made between bovine chymotrypsin and chymotrypsin isolated from the spiny dogfish (squalus acanthias). the major difference between the two enzymes was observed in the molecular activity (kcat), with the dogfish enzyme being two to three times more active than the bovine enzyme. the exact difference was dependent on the substrate and assay conditions. the two enzymes showed similar kinetic properties with respect to the following: similar inhibition by ... | 1987 | 3608434 |
| the elasmobranch renal corpuscle: fine structure of bowman's capsule and the glomerular capillary wall. | the fine structure of the renal corpuscle of the marine elasmobranch fish, the little skate (raja erinacea), and two species of dogfish sharks, the spiny dogfish (squalus acanthias) and the smooth dogfish (mustelus canis), was studied by light microscopy and by transmission (thin sections, freeze-fracture replicas) and scanning electron microscopy. bowman's capsule was lined by ciliated cells, similar to those of the first part of the tubule, at the urinary pole and squamous cells in the zone be ... | 1987 | 3631544 |
| characterization of endorphins from the pituitary of the spiny dogfish squalus acanthias. | opioid-like immunoreactive material was extracted from the pituitary and brain of the spiny dogfish shark squalus acanthias. the immunoreactive material in the pituitary extracts was purified to apparent homogeneity by reverse phase high performance liquid chromatography and subsequently characterized by amino acid analysis, edman degradation and fast atom bombardment mass spectrometry. the largest opioid-like peptide isolated contained 30 amino acids and showed 80 percent homology with salmon e ... | 1986 | 3714530 |
| slow biliary elimination of methyl mercury in the marine elasmobranchs, raja erinacea and squalus acanthias. | the present study examined the ability of two marine elasmobranchs (raja erinacea, little skate, and squalus acanthias, spiny dogfish shark) to excrete methyl mercury into bile, a major excretory route in mammals. 203hg-labeled methyl mercury chloride was administered via the caudal vein, and bile collected through exteriorized cannulas in the free swimming fish. skates and dogfish sharks excreted only a small fraction of the 203hg into bile over a 3-day period: in the skate, the 3-day cumulativ ... | 1986 | 3764924 |
| isolation, purification, and the sequence of relaxin from spiny dogfish (squalus acanthias). | a relaxin-like molecule has been isolated from the ovaries of the spiny dogfish (squalus acanthias) which consists, like porcine relaxin, of two chains linked by the insulin-type disulfide bonds. the total number of amino acids is 54 of which 24 are in the a chain and 30 in the b chain. the molecular masses, calculated from the amino acid compositions, are 2510 da for the a chain and 3370 da for the b chain, making a total of 5880 da. the n-terminus of the b chain is protected by a 5-oxoproline ... | 1986 | 3780747 |
| active chloride transport in rabbit thick ascending limb of henle's loop and elasmobranch rectal gland: chloride fluxes in isolated plasma membranes. | to investigate directly whether a sodium-potassium-chloride cotransport system is operating in the mammalian thick ascending limb of henle's loop (talh) and in the elasmobranch rectal gland, plasma membrane vesicles were prepared from talh cells isolated from rabbit kidney outer medulla and from rectal glands of squalus acanthias, and chloride uptake was measured by a rapid filtration technique. chloride uptake into talh vesicles in the presence of a 25 mm na2so4, 25 mm k2so4 gradient reached 70 ... | 1985 | 3837022 |
| tissue and species specificity of unmasked nuclear acceptor sites for the estrogen receptor of squalus testes. | the testicular estrogen receptor of the shark squalus acanthias is restricted to nuclear subfractions when tissue is homogenized in low salt buffers and adheres tightly to nuclei and dna-cellulose even when exposed to high salt conditions. therefore, we examined the binding characteristics of this receptor to chromatin subfractions from homologous and heterologous tissues. squalus chromatin linked to cellulose and partially deproteinized by 0-8 m guanidine hydrochloride (guhcl) gave extraction p ... | 1986 | 3943492 |
| the elasmobranch kidney. iii. fine structure of the peritubular sheath. | in the kidney of two elasmobranch fish, the little skate (raja erinacea) and the spiny dogfish (squalus acanthias), each tubular bundle is wrapped by a continuous sheath of extremely flattened cells which are ordered in several closely superimposed layers. thin sections and freeze-fracture replicas demonstrate that extensive tight junctions exist between the cells of this peritubular sheath. the sheath cells lie on a discontinuous basement membrane which suggests that they do not belong to the c ... | 1986 | 3963408 |
| the elasmobranch kidney. i. gross anatomy and general distribution of the nephrons. | the morphology of the little skate (raja erinacea) and spiny dogfish shark (squalus acanthias) nephron has been investigated in sexually mature females by 1) gross observations of the kidney surfaces, 2) vascular injections, 3) scanning electron microscopy, 4) light microscopy. in the little skate, each nephron is highly complex and begins at the urinary pole of the renal corpuscle, which is located between a thin, dorsal bundle zone and a thicker, ventral sinus zone. the nephron loops back and ... | 1985 | 4073531 |
| the elasmobranch kidney. ii. sequence and structure of the nephrons. | the nephron and collecting ducts of the little skate (raja erinacea) and spiny dogfish shark (squalus acanthias) have been investigated by light microscopy of semi-thin sections. parts of the tubules (collecting ducts and distal segments) were identified after tubular injections with microfil or carbon. the bundle zone was studied in serial sections. in the sinus zone transitions between the different segments were recorded. thus, a complete reconstruction of the nephron, its subdivision into se ... | 1985 | 4083520 |
| the isolation and amino acid sequence of an adrenocorticotrophin from the pars distalis and a corticotrophin-like intermediate-lobe peptide from the neurointermediate lobe of the pituitary of the dogfish squalus acanthias. | an adrenocorticotrophic hormone (acth) was isolated from extracts of the pars distalis of the pituitary of the dogfish squalus acanthias by gel filtration and ion-exchange chromatography. it had 15% of the potency of human acth in promoting cortico-steroidogenesis in isolated rat adrenal cells. sequence analysis revealed it to be a nonatria-contapeptide with the following primary structure: ser-tyr-ser-met-glu-his-phe-arg-trp-gly-lys-pro-met-gly-arg-lys-arg-arg-pro-ile-lys-val-tyr-pro-asn-ser-ph ... | 1974 | 4375977 |
| a fraction resembling oxytocin from squalus acanthias: pharmacological comparisons with synthetic peptides. | | 1970 | 5457017 |
| metabolism of glycerol ether-containing lipids in dog fish (squalus acanthias). | dogfish (squalus acanthias) received intrahepatic injections of either palmitic acid-1-(14)c or chimyl alcohol-1-(14)c. the lipids of the liver were then analyzed for incorporated radioactivity. the experiments with labeled palmitic acid demonstrated that fatty acids are reductively incorporated into the alkyl and alkenyl ether chains of glycerolipids. significantly lower specific activities were found for the diacyl alk-1'-enyl ethers and diacyl glycerol ethers than for other glycerol ether-con ... | 1968 | 5685261 |
| the ubiquinone content of animal tissues. a survey of the occurrence of ubiquinone in vertebrates. | 1. a method was developed for the analysis of ubiquinone in animal tissues and the recovery of added ubiquinone tested in liver of the rat, crocodylus porosus and squalus acanthias. 2. the ubiquinone content of heart, liver and gut (or breast muscle in birds) was measured in 67 different animal species, selected to be representative of all the vertebrate classes. 3. the suggestion is advanced that the possession of appreciable amounts of endogenous tissue ubiquinone is usually characteristic of ... | 1967 | 6058111 |
| rat atriopeptin dilates vascular smooth muscle of the ventral aorta from the shark (squalus acanthias) and the hagfish (myxine glutinosa). | | 1991 | 1829471 |
| distinct sequence of gonadotropin-releasing hormone (gnrh) in dogfish brain provides insight into gnrh evolution. | in vertebrates, gonadotropin-releasing hormone (gnrh) belongs to a family of decapeptides characterized by the conservation of residues 1, 2, 4, 9, and 10. in the jawed vertebrates only positions 5, 7, and 8 in the gnrh molecules vary. we have now purified two forms of gnrh from the brains of spiny dogfish (squalus acanthias) by using reverse-phase high-performance liquid chromatography. the primary structures were established by automated edman degradation and mass spectral analysis. the distin ... | 1992 | 1631133 |
| partial characterization of four forms of immunoreactive gonadotropin-releasing hormone in the brain and terminal nerve of the spiny dogfish (elasmobranchii; squalus acanthias). | four forms of immunoreactive gnrh have been detected in tissue extracts of both whole brains and terminal nerves from the spiny dogfish (squalus acanthias). the gnrh forms were characterized using reverse-phase high pressure liquid chromatography (hplc) and immunological recognition with four different antisera. three of these forms possess immunological and chromatographic properties consistent with known forms of gnrh: mammalian gnrh, chicken gnrh-ii and salmon gnrh. an additional form, with a ... | 1992 | 1585016 |
| c-type natriuretic peptides stimulate chloride secretion in the rectal gland of squalus acanthias. | homologous shark c-type natriuretic peptide (scnp) was infused as a bolus and as a constant infusion in the isolated perfused rectal gland of the same species, squalus acanthias. scnp was a potent stimulator of chloride secretion similar in its dose-response curve to vasoactive intestinal peptide. scnp was equipotent with killifish cnp but more potent than human cnp (hcnp). truncated and substituted, forms of hcnp were also capable of stimulation of chloride secretion in the order hcnp greater t ... | 1992 | 1566937 |
| the primary structure of peptide y (py) of the spiny dogfish, squalus acanthias: immunocytochemical localisation and isolation from the pancreas. | 1. endocrine cells within islets, exocrine parenchyma and ductal epithelium in the pancreas of the spiny dogfish, squalus acanthias, were immunostained with an antiserum to the c-terminal region of mammalian neuropeptide y (npy). 2. radioimmunoassay of pancreatic extracts with the same antiserum detected immunoreactivity in the dorsal lobe (338 pmol/g) and ventral lobe (433 pmol/g). reverse phase hplc analysis of both extracts resolved a single immunoreactive peptide. 3. the primary structure of ... | 1992 | 1526112 |
| immunohistochemical localisation of natriuretic peptides in the brains and hearts of the spiny dogfish squalus acanthias and the atlantic hagfish myxine glutinosa. | the avidin-biotin peroxidase technique was used to determine the distribution of natriuretic peptides in the hearts and brains of the dogfish squalus acanthias and the atlantic hagfish myxine glutinosa. three antisera were used: one raised against porcine brain natriuretic peptide which cross-reacts with atrial natriuretic and c-type natriuretic peptides (termed natriuretic peptide-like immunoreactivity); the second raised against porcine brain natriuretic peptide which cross-reacts with c-type ... | 1992 | 1486606 |
| study of the ca2+/na+ exchange mechanism in vesicles isolated from apical membranes of lens epithelium of spiny dogfish (squalus acanthias) and bovine eye. | apical membrane vesicles of dogfish and bovine lens epithelium were prepared by differential centrifugation and mg2+ precipitation. enrichment of the apical enzyme markers, for na+,k(+)-atpase was achieved. na+,k(+)-atpase was enriched 25.9-fold and 23.6-fold for dogfish and bovine lens epithelia, respectively, and acid phosphatase was enriched 10.4-fold and 12.6-fold, respectively. there was no enrichment of the cytoplasmic marker, nadh reductase. the majority of the apical membrane vesicles is ... | 1992 | 1330661 |
| purification and localization of brain-type creatine kinase in sodium chloride transporting epithelia of the spiny dogfish, squalus acanthias. | the targeting of creatine kinase isoenzymes to specific sites within muscle cells provides a system for the regeneration of atp in situ from adp and creatine phosphate. we have recently reported the colocalization of brain-type (b) creatine kinase and the nonsarcomeric mitochondrial creatine kinase isoenzymes in the thick ascending limb of the loop of henle in the rat kidney, suggesting that creatine kinase may regenerate atp for sodium transport (friedman, d.l., and perryman, m.b. (1991) j. bio ... | 1992 | 1310991 |
| nucleotide sequence of the 18s ribosomal ribonucleic acid gene from two teleosts and two sharks and their molecular phylogeny. | the 18s rrna sequence was determined for two teleostean fish species, fundulus heteroclitus and sebastolobus altivelis, and two sharks, squalus acanthias and echinorhinus cookei. to study the molecular phylogeny of these taxa, the sequences were compared with 18s rrna sequences of the coelacanth latimeria chalumnae, the frog xenopus laevis, and humans. maximum parsimony analysis of the sequences resulted in a single most parsimonious tree that is in agreement with the expected phylogeny. the cor ... | 1992 | 1308203 |
| topological analysis of the brain stem of the sharks squalus acanthias and scyliorhinus canicula. | | 1976 | 1270611 |
| biliary secretion in elasmobranchs. ii. hepatic uptake and biliary excretion of organic anions. | [35s]bromosulfophthalein ([35c]bsp), [14c]sodium taurocholate ([14c]natc), and 10 mg of unlabeled bsp.and of phenol-3,6-dibromophthalein disulfonate (dbsp) per kilogram body weight were injected in the caudal artery of free-swimming dogfish sharks (squalus acanthias) and small skates (raja erinacea). twenty-four hours later, 85.8 +/- 15.7% of [35s]bsp was recovered in bile and liver in dogfish and 78.4 +/- 9.9% in skates. similar results were obtained for [14c]natc. unlabeled bsp or dbsp (10 mg/ ... | 1976 | 1267029 |
| selective hepatic uptake and biliary excretion of 35s-sulfobromophthalein in marine elasmobranchs. | the hepatic metabolism of 35s-sulfobromophthalein was studied in the free-swimming elasmobranchs, squalus acanthias (spiny dogfish shark) and raja erinacea (small skate), to evaluate the physiological significance of biliary excretion of organic anions in marine vertebrates. twenty-four hours after intra-arterial injection, 85.8 +/- 15.7% of the administered dose was recovered in bile and liver in dogfish and 78.4 +/- 9.9% in skates. more than 85% of bsp in bile was in unconjugated form in both ... | 1976 | 1248686 |
| the primary structure of the hemoglobin of the dogfish shark (squalus acanthias). antagonistic effects of atp and urea on oxygen affinity of an elasmobranch hemoglobin. | the amino-acid sequence of the hemoglobin of the dogfish shark (squalus acanthias) is presented. the alpha-chains consist of 141 residues and show a thr/ser ambiguity at position 3. the beta-chains consist of 142 residues and evidently have no d-helix; they show an asn/tyr ambiguity at position 104. both chains have free n-terminal amino acids. the phylogenetic distance from the human alpha- and beta-chains is indicated by 49.3% and 56.2% amino-acid exchanges. the primary structure is discussed ... | 1985 | 4027000 |
| amino acid sequence of dogfish trypsin. | the amino acid sequence of pancreatic trypsin from the spiny pacific dogfish (squalus acanthias) has been determined and compared with the sequences of bovine and porcine trypsin. dogfish trypsin contains one less amino acid residue (222) than the other two enzymes. two-thirds of the residues in corresponding positions in dogfish and bovine trypsin are identical and the sequences ofall three enzymes are homologous. of the 223 amino acid residues of bovine trypsin, 77 are replaced without signifi ... | 1975 | 1092332 |
| bilirubin metabolism in the spiny dogfish, squalus acanthias, and the small skate, raja erinacea. | 1. the main bilirubin conjugate in bile of spiny dogfish (squalus acanthias) and small skate (raja erinacea) is bilirubin monoglucuronide. 2. microsomal preparations from dogfish and small skate liver have similar bilirubin udpglucuronyltransferase (udpgt) activity and catalyze the conjugation of bilirubin with glucose from udpglucose. 3. the activity of bilirubin glucosidation (udpgt) was 0.5 times udpg1t activity in dogfish and 0.15 times in skate liver microsomes. 4. sodium cholate increased ... | 1977 | 318241 |
| inhibition of the purified sodium-potassium activated adenosinetriphosphatase from the rectal gland of squalus acanthias by antibody against the glycoprotein subunit. | | 1975 | 124172 |
| [immunofluorescent demonstration of pancreatic polypeptide (pp) in pancreas and digestive tube of bony and cartilaginous fish]. | when antisera specific against bovine pp (bpp) were used, immunoreactive parenchymal cells were observed in the endocrine pancreas and in the gastro-intestinal tract of the teleost bony fish cottus scorpius, as well as in the pancreas of the elasmobranchian cartilaginous fish squalus acanthias. of the two principal islets of cottus, pp-cells were located selectively to that in the pyloric region. | 1978 | 96970 |
| molecular evolution of glycogen phosphorylase and aminotransferases of vertebrate muscle tissue. | comparative biochemical studies on phosphorylase b, aspartate aminotransferase and alanine aminotransferase in muscles of various vertebrates (the lamprey lampetra fluviatilis, dogfish squalus acanthias, rays dasyatis pastinaca and raja clavata, teleosts scorpaena porcus, spicara smaris, esox lucius, tinca tinca, abramis brama, lucioperca lucioperca, cyprinus carpio, salmo ischchan, frog rana temporaria, tortoise testudo horsfieldi) revealed some peculiarties of their molecular evolution. it was ... | 1977 | 17251 |
| physiology and chemistry of cerebrospinal fluid, aqueous humor and endolymph in squalus acanthias. | by means of the appropriate isotopes injected into the spiny dogfish, squalus acanthias, the transfer of all major ions into cerebrospinal fluid (csf), aqueous humor (a) and endolymph (e) was studied. in addition, the effect of raising pco2 in sea-water upon hco3- concentration of these fluids was measured. in the several types of experiments, acetazolamide or methazolamide was used to inhibit completely carbonic anhydrase. the rates of fluid formation and ion transfer in csf and a were fairly c ... | 1977 | 15042 |
| biliary secretion in elasmobranchs. i. bile collection and composition. | bile composition and secretion were studied in tow elasmobranch species, squalus acanthias (spiny dogfish shark) and raja erinacea (small skate), after ligation of the common duct and insertion of cannulas into the gallbladder lumen. fish were then allowed to swim freely in large pools and bile was collected in balloons attached to the externalized cannulas. both species secreted bile for periods of 4-7 days at a maximum rate of 1.77 +/- .89 ml/kg per 24 h in squalus acanthias and 2.66 +/- .89 m ... | 1976 | 4983 |
| haemodynamic effects of secretory agents on the isolated elasmobranch rectal gland. | perfusion flow rate in the isolated elasmobranch rectal gland, perfused at in vivo pressures, was measured in scyliorhinus canicula l. and squalus acanthias l. flow through the secretory parenchyma of the gland was reduced in the presence of concentrations of catecholamines in the physiological range, an effect mediated via alpha-adrenergic receptors within the gland vasculature. flow through the non-secretory vascular shunts of the rectal gland was unaffected. the vasoconstriction induced by no ... | 1983 | 6304224 |
| an active cytochrome c oxidase that has no tightly bound cardiolipin. | bovine and dogfish (squalus acanthias) heart submitochondrial particles and cytochrome c oxidase (ec 1.9.3.1) were prepared. biphasic eadie--hofstee plots from steady-state polarographic assays were obtained for both species. phospholipid analyses indicated that cardiolipin was absent from this active dogfish enzyme. | 1983 | 6307267 |
| role of calcium in camp-mediated effects in the elasmobranch rectal gland. | the effects of a23187 and verapamil on the vasomotor and secretory effects of adenosine 3',5'-cyclic monophosphate (camp) in the rectal gland were investigated in scyliorhinus canicula and squalus acanthias. a23187 was a potent vasoconstrictor in the gland and reversed the vasodilatory action of camp in glands constricted with norepinephrine. verapamil, like camp, prevented the vasoconstriction induced in the gland by norepinephrine. a23187 had no effect on the secretory activity (measured as ou ... | 1983 | 6318578 |
| the phospholipids associated with cytochrome c oxidase isolated from beef, dogfish and cod heart. | beef (bos taurus), dogfish (squalus acanthias) and cod (gadus morhua) heart submitochondrial particles and cytochrome c oxidase (ec 1.9.3.1) were prepared. the head groups and side chains of the phospholipids associated with these samples were analysed quantitatively. the fish phospholipids contained a higher proportion of long chain poly-unsaturated fatty acids than was found in the beef samples. the enzyme fraction showed no head group or fatty acyl chain preference when compared with the comp ... | 1984 | 6325085 |
| selachian tooth development: ii. immunolocalization of amelogenin polypeptides in epithelium during secretory amelogenesis in squalus acanthias. | we have determined the distribution of amelogenin polypeptides in an order of elasmobranchs using indirect immunofluorescence with rabbit polyclonal antibodies prepared to purified murine amelogenins. we find that amelogenins are definitely present within the inner enamel epithelium prior to the production of the extracellular matrix component termed "enameloid" (row ii developing tooth organs). during subsequent stages of selachian tooth development (row iii tooth organs), immunofluorescence st ... | 1983 | 6348070 |
| dogfish insulin. primary structure, conformation and biological properties of an elasmobranchial insulin. | insulin from an elasmobranch, the spiny dogfish (squalus acanthias) has been purified to near homogeneity by means of acid-ethanol extraction and salt precipitation. the amino acid sequences of the performic-acid-oxidised a and b chains have been determined and exhibit some unusual features. the a chain contains a total of 22 amino acids; only the insulin from coypu (a member of the rodentia suborder, hystricomorpha), has previously been reported to contain an extension past the a21 asparagine. ... | 1983 | 6352261 |
| effects of relaxin and insulin on reproductive tract size and early fetal loss in squalus acanthias. | these experiments demonstrate that both porcine relaxin and bovine insulin can increase the cervical cross-sectional area in squalus acanthias. when given after estradiol priming, the magnitude of this response is greater. this effect is limited to stage c females in which pregnancy is over 75% complete. the overall result is premature loss of developing fetuses. the effect of relaxin or insulin on cervical cross-sectional area and fetal loss is unrelated to an effect on blood sugar. cervical we ... | 1984 | 6383486 |
| effects of drugs and nerve stimulation on the spleen and arteries of two species of dogfish, scyliorhinus canicula and squalus acanthias. | the effects of drugs and nerve stimulation on the spleen of 2 species of dogfish have been examined by experiments with perfused spleens and isolated spleen and artery strips. adrenaline, noradrenaline and phenylephrine, acting via alpha adrenoceptors, constrict the perfused spleen of both species, thereby releasing erythrocytes, and contract the isolated spleen and artery strips. phenotolamine competitively antagonizes the excitatory effects of adrenergic agonists. the responses of the spleen t ... | 1975 | 1189932 |
| [evaluation of the protein quality of meat flour from the tollo shark (squalus acanthias)]. | the protein quality of tollo flour evaluated by various biological methods, including digestibility, is reported. the product contained 91.52% crude protein and 69.86% true protein, the difference being non-protein nitrogen, mainly urea. due to this reason the biological evaluations were carried out with different shark flour concentrations and evaluated at different lengths of time with each method. diets containing 0, 3, 6, 9 and 12% shark flour were prepared and evaluated by the per, npr, and ... | 1984 | 6532342 |
| glutamine- and n-acetyl-l-glutamate-dependent carbamoyl phosphate synthetase from micropterus salmoides. purification, properties, and inhibition by glutamine analogs. | the glutamine- and n-acetyl-l-glutamate-dependent carbamoyl phosphate synthetase iii present in liver of largemouth bass (micropterus salmoides) has been highly purified. the properties of the enzyme are generally similar to the properties of the carbamoyl phosphate synthetase iii from spiny dogfish (squalus acanthias) previously described (anderson, p. m. (1981) j. biol. chem. 256, 12228-12238). however, the bass enzyme is not subject to self-association, and the effects of urea and, particular ... | 1983 | 6602805 |
| [identification of 2 new neurohypophyseal hormones, valitocin (val 8 -oxytocin) and aspartocin (asn 4 -oxytocin) in a selachian fish, the spiny dog-fish (squalus acanthias)]. | | 1972 | 4622083 |
| urea efflux from the squalus acanthias pup: the effect of stress. | | 1985 | 4093759 |
| the involvement of melanotrophins in physiological colour change in the dogfish scyliorhinus canicula. | desacetylated alpha-, beta-, and gamma-msh purified from the neurointermediate lobe of the pituitary gland of the dogfish squalus acanthias were all equipotent in turning partially hypophysectomized dogfish, scyliorhinus canicula, dark. however, each possessed less than 2% of the melanotrophic activity of either acetylated mammalian alpha-msh or synthetic acetylated squ. acanthias alpha-msh. these results suggest that acetylation is much more important than amidation in determining melanotrophic ... | 1984 | 6510695 |
| characterization of microtubules isolated from dogfish (squalus acanthias and scyliorhinus canicula) brain in the absence of glycerol. | microtubules were isolated by two cycles of assembly-disassembly from dogfish brain in the absence of glycerol. the microtubule protein preparation consist mainly of tubulin as characterized by sds-polyacrylamide gel electrophoresis, but tau and high molecular weight microtubule associated proteins (maps) were also identified, in addition to several other maps. the microtubules were cold-sensitive and had an assembly temperature optimum at 21-25 degrees c. ca2+, at a concentration of 1 mm or hig ... | 1983 | 6617157 |
| characterization of the endogenous intestinal peptide that stimulates the rectal gland of scyliorhinus canicula. | it has been postulated that gut peptides play a major role in the regulation of rectal gland secretion in elasmobranchs. an isolated perfused rectal gland secretion in elasmobranchs. an isolated perfused rectal gland preparation was developed for scyliorhinus canicula that responded to dibutyryl 3',5'-cyclic monophosphate plus 3-isobutyl-1-methylxanthine, increasing chloride clearance rates threefold over basal levels. activity was stimulated by an endogenous peptide, isolated in pur form by rev ... | 1995 | 7541963 |
| molecular cloning of the myelin basic proteins in the shark, squalus acanthias, and the ray, raja erinacia. | myelin basic proteins (mbps) are a family of alternatively spliced isoforms present in myelin sheaths of most vertebrates. a reverse transcriptase-polymerase chain reaction (rt-pcr) approach was used to clone mbp isoforms in species representing two superorders of elasmobranchs: squalus acanthias, representing squalomorph sharks, and raja erinacia, representing batoidea rays. two products were generated from each species. the larger product encoded a 155 amino acid protein, the same size as mbps ... | 1993 | 7692075 |
| isolation and characterization of the cdna encoding the spiny dogfish shark (squalus acanthias) form of cytochrome p450c17. | cytochrome p450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. this protein possesses two enzymatic activities. the 17 alpha-hydroxylase activity results in the introduction of a hydroxyl group at the 17 alpha-position. the resultant 17 alpha-hydroxylated, c21 pregnene is converted to a c19 androgen by the c17,20-lyase activity. a cdna library was constructed from poly(a)-enriched mrna isolated from spiny dogfi ... | 1995 | 7738515 |
| molecular evolution of shark c-type natriuretic peptides. | c-type natriuretic peptides (cnp) of varying length were isolated from the atrium or ventricle of a shark, lamna ditropis and their amino acid sequences were determined. although the sequence of lamna cnp was highly homologous to those of other cnps sequenced to date, the lamna cnp-41, the longest cnp identified in this study, has one amino acid replacement from those of triakis scyllia and scyliorhinus canicula, and three amino acid replacements from that of squalus acanthias. the degree of sim ... | 1994 | 7765421 |
| camp-activated cl- channels in primary cultures of spiny dogfish (squalus acanthias) rectal gland. | whole cell and single-channel patch-clamp techniques were used to identify and characterize the cl- currents responsible for adenosine 3',5'-cyclic monophosphate (camp)-mediated cl- secretion in the rectal gland of the spiny dogfish (squalus acanthias). during whole cell recordings, in cultured rectal gland cells forskolin (10 microm) and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (400 microm) stimulated a 28-fold increase in cl- conductance (n = 10). this camp-activated conducta ... | 1995 | 7840162 |
| genetic basis for tissue isozymes of glutamine synthetase in elasmobranchs. | tissue-specific isozymes of glutamine synthetase are present in elasmobranchs. a larger isozyme occurs in tissues in which the enzyme is localized in mitochondria (liver, kidney) whereas a smaller form occurs in tissues in which it is cytosolic (brain, spleen, etc.). the nucleotide sequence of spiny dogfish shark (squalus acanthias) liver glutamine synthetase mrna, derived from its cdna, shows there are two in-frame initiation codons (aug) at the n-terminus which will account for the size differ ... | 1994 | 7914934 |
| carbamyl phosphate synthetase iii, an evolutionary intermediate in the transition between glutamine-dependent and ammonia-dependent carbamyl phosphate synthetases. | the amino acid sequence of carbamyl phosphate synthetase (cps) iii from liver of spiny dogfish shark squalus acanthias was deduced from the nucleotide sequence of its cdna. alignment of the derived amino acid sequence of cps iii with sequences of rat and frog cps i and hamster cps ii reveals a high degree of amino acid identity, indicating that cps iii shares the same common ancestral genes as cpss i and ii. all of the cpss examined show a high conservation of sequences in the adenine nucleotide ... | 1994 | 7932737 |
| physiological and immunocytochemical evidence for a putative h-k-atpase in elasmobranch renal acid secretion. | the mechanism of renal acid secretion in marine fish is largely unknown. we explored whether h(+)-k(+)-adenosinetriphosphatase (h(+)-k(+)-atpase) is present and functional in acid secretion in the kidney of the elasmobranch spiny dogfish shark, squalus acanthias. in whole animal studies, a specific inhibitor of mammalian h(+)-k(+)-atpase, sch-28080, abolished greater than 87% of basal (62 mg/kg) and 75% of imidazole-stimulated titratable acid excretion (5 and 62 mg/kg). antibodies directed again ... | 1994 | 7943360 |
| c-type natriuretic peptide receptors and signaling in rectal gland of squalus acanthias. | recent evidence suggests that the newly described natriuretic peptide, c-type natriuretic peptide (cnp), may be the circulating form of natriuretic peptide in the shark. in the shark cnp has a major site of action in the rectal gland, which augments chloride secretion in response to stimulation by volume loading or cnp infusion. we therefore examined the shark rectal gland for natriuretic peptide receptors and determined the presence of guanylate cyclase-linked receptors and non-guanylate cyclas ... | 1993 | 8095372 |
| photoaffinity labeling of the ah receptor: phylogenetic survey of diverse vertebrate and invertebrate species. | the mammalian aromatic hydrocarbon (ah) receptor is a soluble protein involved in the regulation of gene expression by halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). little is known, however, about the presence and properties of this receptor in nonmammalian species. in these studies, we sought evidence for an ah receptor in the liver or liver-equivalent of diverse species of invertebrate and vertebrate animals. velocity sedimentation analysis of hepatic cy ... | 1994 | 8161208 |
| culture of intact sertoli/germ cell units and isolated sertoli cells from squalus testis. ii. stimulatory effects of insulin and igf-i on dna synthesis in premeiotic stages. | to investigate growth control mechanisms during spermatogenesis in vitro, [3h]thymidine incorporation into acid-insoluble macromolecules was used to quantify dna synthesis in cultured spermatocysts (intact sertoli cell/germ cell clones) derived from premeiotic (prm), meiotic (m), and postmeiotic (pom) regions of dogfish (squalus acanthias) testis. forty-eight hours after seeding in basal medium, dna synthesis was > 7-fold higher in prm cysts than in other stages, thus verifying the staging proce ... | 1993 | 8409903 |
| squalamine: an aminosterol antibiotic from the shark. | in recent years, a variety of low molecular weight antibiotics have been isolated from diverse animal species. these agents, which include peptides, lipids, and alkaloids, exhibit antibiotic activity against environmental microbes and are thought to play a role in innate immunity. we report here the discovery of a broad-spectrum steroidal antibiotic isolated from tissues of the dogfish shark squalus acanthias. this water-soluble antibiotic, which we have named squalamine, exhibits potent bacteri ... | 1993 | 8433993 |
| c-type natriuretic peptides are potent dilators of shark vascular smooth muscle. | previous studies of the effects of c-type natriuretic peptides (cnp) in intact mammals have demonstrated limited hypotensive responses, in contrast to other natriuretic peptides. our previous studies, on isolated vascular smooth muscle (vsm) from various fish species, utilizing either mammalian or non-homologous fish atrial natriuretic peptides (anp), have demonstrated vasodilation with a relatively high sensitivity (ec50 approximately 5 nm). the recent sequencing of a c-type natriuretic peptide ... | 1993 | 8459233 |
| functional expression of recombinant spiny dogfish shark (squalus acanthias) cytochrome p450c17 (17 alpha-hydroxylase/c17,20-lyase) in yeast (pichia pastoris). | the cdna encoding the spiny dogfish shark (squalus acanthias) testicular form of cytochrome p450c17 (cyp17) was used to direct the heterologous expression of a functional enzyme in yeast (pichia pastoris). this protein possesses two enzymatic activities: 17 alpha-hydroxylase and c17,20-lyase reactions. cytochrome p450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. this study describes the culture conditions and ... | 1996 | 8579376 |
| molecular cloning of a human cdna encoding a trifunctional enzyme of carbamoyl-phosphate synthetase-aspartate transcarbamoylase-dihydroorotase in de novo pyrimidine synthesis. | a human cad cdna encoding a trifunctional enzyme of carbamoylphosphate synthetase-aspartate transcarbamoylase-dihydroorotase, which catalyzes the first three steps of de novo pyrimidine nucleotide biosynthesis, was cloned from a human fibroblast cell line of tig-1-20 by polymerase chain reaction (pcr). the predicted open reading frame encodes a protein of 2,225 amino acids with a deduced molecular weight (mr) of 242,913. the deduced amino acid sequence exhibits 95.3 and 76.1% identity with the c ... | 1996 | 8619816 |
| whole-cell conductive properties of rat pancreatic acini. | acetylcholine-controlled exocrine secretion by pancreatic acini has been explained by two hypotheses. one suggests that nacl secretion occurs by secondary active secretion as has been originally described for the rectal gland of squalus acanthias. the other is based on a "push-pull" model whereby cl- is extruded luminally and sequentially taken up basolaterally. in the former model cl- uptake is coupled to na+ and basolateral k+ conductances play a crucial role, in the latter model, na+ uptake s ... | 1996 | 8662275 |
| etb-type receptors mediate endothelin-stimulated contraction in the aortic vascular smooth muscle of the spiny dogfish shark, squalus acanthias. | using various agonists, and the specific antagonist bq-123, we have examined the sensitivity to endothelin of the vascular smooth muscle of the ventral aorta of the spiny dogfish shark, squalus acanthias. human endothelin-1 produced significant contraction of isolated vascular smooth muscle rings, with an ec50 of 10 nmol.l-1. the presence of an intact endothelium did not alter this response but the magnitude of the contraction was greater in rings with an intact endothelium. the response to 0.2 ... | 1996 | 8882511 |
| hypophysial and extrahypophysial projections of the neurosecretory system of cartilaginous fishes: an immunocytochemical study using a polyclonal antibody against dogfish neurophysin. | immunocytochemistry using antibodies against the neurohypophysial nonapeptides has given equivocal results regarding relevant aspects of the classical neurosecretory system of elasmobranchs. the lack of antibodies reacting with the elasmobranch neurophysins (nps) has prevented the study of this neurosecretory system by nps immunocytochemistry. this led us to purify nps from scyliorhinus canicula, and to use them to raise a polyclonal antibody. this antibody reacted strongly with the elasmobranch ... | 1996 | 8889935 |
| the promoter region of the carbamoyl-phosphate synthetase iii gene of squalus acanthias. | carbamoyl-phosphate synthetase iii (cpsase iii) of squalus acanthias (spiny dogfish) is a nuclear-encoded mitochondrial enzyme that catalyzes glutamine-dependent formation of carbamoyl phosphate for urea synthesis. in this paper we report the results of cloning a 10-kb segment of genomic dna which includes the region flanking the 5' end of the spiny dogfish cpsase iii gene. a total of 1,295 base pairs of sequence straddling the start codon was obtained. primer extension experiments revealed that ... | 1996 | 8995057 |
| heterologous expression of the spiny dogfish shark (squalus acanthias) cytochrome p450c17 (17 alpha-hydroxylase) in escherichia coli. | cytochrome p450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. this protein possesses two enzymatic activities. the 17-alpha-hydroxylase activity introduces a hydroxyl group into the steroid nucleus. the resultant 17-alpha-hydroxylated, c(21) pregnenes can be converted to a c(19) androgen by the c(17,20)-lyase activity. the cdna encoding the spiny dogfish shark (squalus acanthias) testicular form of cytochrome ... | 1996 | 8998961 |
| isolation of the putative cdna encoding cholesterol side chain cleavage cytochrome p450 (cyp11a) of the southern stingray (dasyatis americana). | cholesterol side chain cleavage cytochrome p450 (p450scc; cyp11a) catalyzes the first step in the production of steroid hormones. by utilizing degenerate oligonucleotide primers in a reverse transcriptase-coupled polymerase chain reaction (rt-pcr), a specific 252 bp fragment of the putative p450scc was amplified from rna of interrenal tissue (the adrenal cortex homolog) from the southern stingray (dasyatis americana), blacktip shark (carcharhinus limbatus), and the spiny dogfish shark (squalus a ... | 1997 | 9073075 |
| digestion of the 1-o-alkyl diacylglycerol ethers of atlantic dogfish liver oils by atlantic salmon salmo salar. | dogfish (squalus acanthias) liver poses a waste disposal problem in canada because it is not utilized for any commercial purpose. the liver of atlantic dogfish, which is often up to 20% of the weight of the fish, contains 40-70% oil. the oil contains about 30-40% 1-o-alkyl diacylglycerol ethers (dage) which render it unacceptable for human use, and it has also not been considered satisfactory for animal feed use. polyunsaturated fatty acids (20:5n-3 and 22:6n-3) are present in dogfish liver oils ... | 1997 | 9075189 |
| distribution and characterization of natriuretic peptide receptors in the gills of the spiny dogfish, squalus acanthias. | the distribution and nature of natriuretic peptide receptors (npr) in the gills of dogfish, squalus acanthias, were examined by tissue section autoradiography, competition analysis, protein electrophoresis, guanylate cyclase (gc) assays, and molecular cloning. specific np binding occurred on the gill filaments, but not on the interbranchial septum or gill arch. the binding was densest on the efferent edge of the gills. higher resolution light-microscopic examination of emulsion-coated sections s ... | 1997 | 9204367 |
| 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 |
| extracellular carbonic anhydrase and an acid-base disequilibrium in the blood of the dogfish squalus acanthias | the electrometric [delta]ph method and an in vitro radioisotopic hco3- dehydration assay were used to demonstrate the presence of true extracellular carbonic anhydrase (ca) activity in the blood of the pacific spiny dogfish squalus acanthias. an extracorporeal circulation and stopflow technique were then used to characterise the acid­base disequilibrium in the arterial (postbranchial) blood. during the stopflow period, arterial ph (pha) decreased by 0.028±0.003 units (mean ± s. ... | 1997 | 9317577 |
| subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis in the batrachoidid fishes opsanus beta, opsanus tau and porichthys notatus | the subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis were examined in three representatives of fishes of the family batrachoididae, the gulf toadfish (opsanus beta), the oyster toadfish (opsanus tau) and the plainfin midshipman (porichthys notatus). the primary objective of the study was to compare the biochemical characteristics of these fishes, which represent a range between ammoniotelism and ureotelism (o. beta being facultatively u ... | 1995 | 9318521 |
| role of guanylyl cyclase receptors for cnp in salt secretion by shark rectal gland. | the role of c-type natriuretic peptide (cnp) and its guanylyl cyclase-linked receptors in mediating salt secretion by the rectal gland of the spiny dogfish shark (squalus acanthias) was investigated using hs-142-1, a competitive inhibitor of the binding of natriuretic peptides to their guanylyl cyclase receptors. cnp binds to receptors and activates guanylyl cyclase in rectal gland membranes in a way that is inhibited by hs-142-1. guanylyl cyclase activation in rectal gland membranes is far more ... | 1997 | 9362305 |
| n-acetyl-l-glutamate and the urea cycle in gulf toadfish (opsanus beta) and other fish. | carbamoyl phosphate synthetase i (cpsase i) catalyzes the first reaction of the urea cycle in mammalian ureotelic species. the positive allosteric cofactor n-acetyl-l-glutamate (aga) is required for cpsase i activity and is important for regulation of the urea cycle. a similar enzyme, cpsase iii, catalyzes this reaction in fish; cpsase iii differs from cpsase i in that it utilizes glutamine as the nitrogen-donating substrate instead of ammonia. aga also stimulates the cpsase iii-catalyzed reacti ... | 1998 | 9466820 |
| vasoactive intestinal peptide, forskolin, and genistein increase apical cftr trafficking in the rectal gland of the spiny dogfish, squalus acanthias. acute regulation of cftr trafficking in an intact epithelium. | defective trafficking of the cystic fibrosis transmembrane conductance regulator (cftr) is the most common cause of cystic fibrosis. in chloride-secreting epithelia, it is well established that cftr localizes to intracellular organelles and to apical membranes. however, it is controversial whether secretagogues regulate the trafficking of cftr. to investigate whether acute hormonal stimulation of chloride secretion is coupled to the trafficking of cftr, we used the intact shark rectal gland, a m ... | 1998 | 9466967 |
| dogfish shark (squalus acanthias) testes contain a relaxin. | relaxin is a 6-kd polypeptide that exerts important hormonal effects in many female mammals. relaxin is produced by the ovary, placenta, or uterus in many mammalian species. the functions of relaxin in the male mammal are not yet firmly established, but there is some evidence suggesting an exocrine effect on sperm motility and fertilizability. in the male mammals that have been studied, relaxin is produced by the prostate gland (human) or seminal vesicles (boar). however, in the bird, the testis ... | 1998 | 9537298 |
| a prostaglandin, not no, mediates endothelium-dependent dilation in ventral aorta of shark (squalus acanthias). | in mammals, the vascular endothelium releases a variety of paracrine factors, including the vasodilatory prostaglandin (pg)i2 and nitric oxide (no), which is generally accepted as the major endothelium-derived relaxing factor (edrf) in mammals. current evidence for the vascular no-edrf system in fishes is contradictory. in addition, the role of pgs in the control of fish vascular tension is also unclear. we have utilized isolated rings of the ventral aorta of the spiny dogfish shark to examine t ... | 1998 | 9575968 |
| cloning of sgk serine-threonine protein kinase from shark rectal gland – a gene induced by hypertonicity and secretagogues. | recently, the cell-volume-regulated serine-threonine protein kinase h-sgk was cloned from a human hepatoma cell line. the sgk gene was shown to be induced by cell shrinkage in many different mammalian cell lines. in this study, two highly conserved serine-threonine protein kinases, sgk-1 and sgk-2, were cloned from rectal gland tissue of the spiny dogfish (squalus acanthias). both kinases showed a distinct pattern of tissue specificity, with high expression levels in kidney, intestine, liver and ... | 1998 | 9683731 |
| studies on the cornea. x. incorporation of 14c-glucosamine into glycosaminoglycans and glycoproteins of elasmobranch corneas, extractability of these components and morphological effects of such extractions. | incorporation of 14c-glucosamine into dogfish (squalus acanthias) corneas occurs primarily in the glycosaminoglycans (gag) and glycoproteins (gp) extractable with elasmobranch ringer's solution but the rate at which this component can be extracted varies inversely with the age (size) of the fish. whereas this fraction represents only one-fourth of the total hexosamine (hex-n) it contains nearly three-fourths of the newly incorporated 14c-glucosamine. the cacl2-extractable hexn contains only 13% ... | 1983 | 6620716 |
| renal handling of taurine in marine fish. | net renal tubular excretion of taurine was demonstrated by clearance techniques in the dogfish, squalus acanthias; the little skate, raja erinacea; and in the winter flounder, pseudopleuronectes americanus. dogfish acclimated to 70% seawater had increased renal excretion of taurine resulting from higher glomerular filtration rates of taurine as well as from increased rats of tubular secretion. tubular secretion of taurine prevailed in the dogfish and flounders measured, whereas it occurred in on ... | 1982 | 7058931 |
| glucose transport across ocular barriers of the spiny dogfish, squalus acanthias. | evidence is presented demonstrating that in the dogfish, squalus acanthias, d-glucose is transported from the blood to the ocular fluid compartments by a mechanism that is consistent with carrier-facilitated transport. across the dogfish aqueous barrier d-glucose is transported 8.4 times faster than l-glucose, whereas this d/l transport ratio is only 5.5 in the rat. similarly, the d/l transport ratio is 12.7 across the dogfish vitreous barrier and only 6.1 across this barrier in the rat. it is e ... | 1982 | 7061971 |
| squalamine, a novel cationic steroid, specifically inhibits the brush-border na+/h+ exchanger isoform nhe3. | squalamine, an endogenous molecule found in the liver and other tissues of squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. the latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. the effect of purified squalamine was examined on cloned na+/h+ exchanger isoforms nhe1, nhe2, and nhe3 stably transfected in ps120 fibroblasts. squalamine (1-h pretreatment) decreased the maximal velocity of rabb ... | 1999 | 9886929 |
| molecular and functional characterization of s-kcnq1 potassium channel from rectal gland of squalus acanthias. | functional and pharmacological data point to the involvement of kcnq1/isk potassium channels in the basolateral potassium conductance of secretory epithelia. in this study, we report the cloning and electrophysiological characterization of the kcnq1 protein from the salt secretory rectal gland of the spiny dogfish (squalus acanthias). the s. acanthias kcnq1 (s-kcnq1) cdna was cloned by polymerase chain reaction (pcr) intensive techniques and showed overall sequence similarities with the kcnq1 po ... | 1999 | 9929573 |