| heterogeneity of na+/k+-atpase from rectal gland of squalus acanthias is not due to alpha isoform diversity. | purified na+/k+-atpase (ec 3.6.1.37) isolated from the rectal gland of squalus acanthias was characterized in ouabain-binding studies and with respect to isoform(s) of the alpha peptide. to avoid enzyme inactivation [3h]ouabain equilibrium binding was carried out at 20 degrees c. the heterogeneity of na+/k+-atpase isolated from shark rectal gland was similar in [3h]ouabain binding as previously seen in hydrolytic studies. the binding isotherms were compatible with the existence of a high-affinit ... | 1999 | 10089563 |
| 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 |
| 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 |
| isolation and characterization of cdna sequences of l-gulono-gamma-lactone oxidase, a key enzyme for biosynthesis of ascorbic acid, from extant primitive fish groups. | most advanced teleosts lack l-gulono-gamma-lactone oxidase (gulo), a key enzyme required for the biosynthesis of ascorbic acid. however, extant representatives of primitive species including sturgeon and many cartilaginous fishes, are exceptional in their ability to synthesize ascorbic acid de novo. in the present study, full-length gulo cdnas were isolated from white sturgeon (acipenser transmontanus) and two shark species belonging to the triakidae (triakis scyllium and mustelus manazo). the o ... | 2007 | 17317254 |
| 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 |
| 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 |
| 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 |
| cloning of two melanocortin (mc) receptors in spiny dogfish: mc3 receptor in cartilaginous fish shows high affinity to acth-derived peptides while it has lower preference to gamma-msh. | we report the cloning and characterization of two melanocortin receptors (mcrs) from the spiny dogfish (squalus acanthias) (sac). phylogenetic analysis shows that these shark receptors are orthologues of the mc3r and mc5r subtypes, sharing 65% and 70% overall amino acid identity with the human counterparts, respectively. the sacmc3r was expressed and pharmacologically characterized in hek293 cells. the radioligand binding results show that this receptor has high affinity for adrenocorticotropic ... | 2004 | 15511238 |
| accurate determination of cd, cr, cu and ni in woodlice and their skins--is moulting a means of detoxification? | cd, cr, cu and ni were determined in two different species of woodlice: porcellio scaber and porcellio dilatatus. both p. scaber and p. dilatatus were cultivated under standardized conditions in a climatic chamber. moreover, skins of the cultivated animals were collected and analysed separately to examine whether moulting is a way of detoxification from these elements. after drying and grinding both animal and skin samples, they were pooled to obtain enough sample material for each species. the ... | 2005 | 15626381 |
| feeding ecology of five commercial shark species of the celtic sea through stable isotope and trace metal analysis. | in order to trace their feeding habits, stable carbon and nitrogen isotope ratios (delta15n and delta13c), as well as trace metal concentrations (zn, cd, fe, cu, se and hg) were analysed in the tissues of five commercial shark species from the celtic sea: the tope shark galeorhinus galeus, the black-mouthed catshark galeus melastomus, the starry smooth hound mustelus asterias, the spiny dogfish squalus acanthias and the lesser-spotted dogfish scyliorhinus canicula. our results were compared to p ... | 2005 | 15925404 |
| 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 |
| unexpected diversity of aryl hydrocarbon receptors in non-mammalian vertebrates: insights from comparative genomics. | ligand-activated receptors are well-known targets of environmental chemicals that disrupt endocrine signaling. genomic approaches are providing new opportunities to understand the comparative biology and molecular evolution of these receptors. one example of this is the aryl hydrocarbon receptor (ahr), a basic-helix-loop-helix (bhlh)-per-arnt-sim (pas) transcription factor through which planar aromatic hydrocarbons cause altered gene expression and toxicity. in contrast to humans and other mamma ... | 2006 | 16902966 |
| 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 |
| rna expression in a cartilaginous fish cell line reveals ancient 3' noncoding regions highly conserved in vertebrates. | we have established a cartilaginous fish cell line [squalus acanthias embryo cell line (sae)], a mesenchymal stem cell line derived from the embryo of an elasmobranch, the spiny dogfish shark s. acanthias. elasmobranchs (sharks and rays) first appeared >400 million years ago, and existing species provide useful models for comparative vertebrate cell biology, physiology, and genomics. comparative vertebrate genomics among evolutionarily distant organisms can provide sequence conservation informat ... | 2007 | 17227856 |
| 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 |
| characterization of an endothelin et(b) receptor in the gill of the dogfish shark squalus acanthias. | endothelins (ets) are potent vasoconstrictive peptides that are secreted by the vascular endothelium and other tissues in vertebrates. previous studies have demonstrated that ets are expressed in a variety of fish tissues and contract various blood vessels. in order to determine if receptors for et are expressed in fish gill tissue, we examined the binding kinetics of (125)i-labeled, human et-1 to membrane fragments isolated from the gill of the dogfish shark, squalus acanthias. (125)i-et-1 boun ... | 1999 | 10574737 |
| the synthesis of spermine analogs of the shark aminosterol squalamine. | aminosterols isolated from the dogfish shark squalus acanthias are promising therapeutic agents in the treatment of infection and cancer. one of these, msi-1436, has been shown to possess antimicrobial activity slightly better than squalamine. in this study, a series of analogs of msi-1436 have been synthesized from stigmasterol. the 7 alpha-hydroxy substituent of msi-1436 was either omitted or the stereochemistry modified to the 7 beta position. also, analogs of msi-1436 with 24-sulfate, 24-ami ... | 2002 | 11856553 |
| the effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (oncorhynchus mykiss) and the marine dogfish (squalus acanthias). | the aim of the present study was to evaluate the effects of endothelin-l-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (oncorhynchus mykiss) and the marine dogfish (squalus acanthias). in both species, endothelin-1 (666 pmol kg(-1)) caused a rapid (within 4 min) reduction (ca. 30-50 mmhg) in arterial blood partial pressure of o2. the effects of endothelin-1 on arterial blood partial pressure of co2 were not synchronised with the changes in o2 partial ... | 2001 | 11765971 |
| transepithelial organic anion transport by shark choroid plexus. | spiny dogfish shark (squalus acanthias) lateral and iv choroid plexuses (cps) are ultrastructurally similar to the corresponding tissues of rat. however, shark iv cp is proportionally larger and easily accessible. moreover, this epithelial sheet can be halved and studied in ussing flux chambers. we have used confocal fluorescence microscopy and radiotracer techniques to characterize transepithelial transport of the organic anions (oas) fluorescein (fl) and 2,4-dichlorophenoxyacetic acid (2,4-d), ... | 2002 | 11959670 |
| squalamine: a polyvalent drug of the future? | the purpose of this mini-review is to summarize and highlight the different advances in our understanding of the antimicrobial and antiangiogenic activity of squalamine, a cationic steroid isolated in 1993 from the dogfish shark squalus acanthias. indeed, squalamine has shown to be useful for the treatment of important diseases such as cancers (lung, ovarian, brain and others), age-related macular degeneration (amd) and the control of body weight in man. all these results led to a question: coul ... | 2005 | 15975047 |
| the effects of dietary sodium loading on the activity and expression of na, k-atpase in the rectal gland of the european dogfish (scyliorhinus canicula). | cdna fragments of both the alpha- and beta-subunits of the na, k-atpase and a cdna fragment of the secretory form of na-k-cl cotransporter from the european dogfish (scyliorhinus canicula) were amplified and cloned using degenerate primers in rt-pcr. these clones were used along with a scftr cdna from the related dogfish shark, squalus acanthias to characterise the expression of mrnas for these ion transporters in the dogfish rectal gland subsequent to an acute feeding episode. following a singl ... | 2002 | 11818240 |
| aquaporin 4 is a ubiquitously expressed isoform in the dogfish (squalus acanthias) shark. | the dogfish ortholog of aquaporin 4 (aqp4) was amplified from cdna using degenerate pcr followed by cloning and sequencing. the complete coding region was then obtained using 5' and 3' race techniques. alignment of the sequence with aqp4 amino acid sequences from other species showed that dogfish aqp4 has high levels (up to 65.3%) of homology with higher vertebrate sequences but lower levels of homology to agnathan (38.2%) or teleost (57.5%) fish sequences. northern blotting indicated that the d ... | 2011 | 22291652 |
| mode of activation of salt secretion by c-type natriuretic peptide in the shark rectal gland. | we studied the modes of activation of the salt-secreting rectal gland of the spiny dogfish, squalus acanthias, by the native cardiac peptide cnp. the stimulatory action of cnp in isolated perfused glands is inhibited by 10 mm procaine, presumably by blocking release of vasoactive intestinal peptide (vip) from nerves. procaine reduces the slope of the dose-response curve of human cnp and that of shark cnp (each p < 0.0001). cnp increases short-circuit current in cultured rectal gland cells from 4 ... | 1999 | 10600920 |
| presence of melanocortin (mc4) receptor in spiny dogfish suggests an ancient vertebrate origin of central melanocortin system. | we report the cloning, expression, pharmacological characterization and tissue distribution of a melanocortin (mc) receptor gene in a shark, the spiny dogfish (squalus acanthias) (sac). phylogenetic analysis showed that this receptor is an ortholog of the mc4 subtype, sharing 71% overall amino acid identity with the human (hsa) mc4 receptor. when expressed and characterized by radioligand binding assay for the natural msh (melanocyte-stimulating hormone) peptides alpha-, beta-, and gamma-msh, th ... | 2003 | 12605672 |
| evidence for na+/ca2+ exchange in the rectal gland of squalus acanthias. | previously we have shown that stimulation of in vitro perfused rectal gland tubules (rgt) of the dog-fish squalus acanthias by adenosine 3',5'-cyclic monophosphate (camp), (as a cocktail comprising 0.1 mmol/l dibutyryl-camp, 10 micromol/l forskolin and 0.1 mmol/l adenosine, hereafter termed stim) leads to an increase in cytosolic ca2+ ([ca2+]i) and that this assists cl- secretion by enhancing basolateral k+ conductance. in the present study we examined the mechanism of the camp-induced increase ... | 1999 | 10650999 |
| identification of a phospholemman-like protein from shark rectal glands. evidence for indirect regulation of na,k-atpase by protein kinase c via a novel member of the fxydy family. | the na,k-atpase provides the driving force for many ion transport processes through control of na(+) and k(+) concentration gradients across the plasma membranes of animal cells. it is composed of two subunits, alpha and beta. in many tissues, predominantly in kidney, it is associated with a small ancillary component, the gamma-subunit that plays a modulatory role. a novel 15-kda protein, sharing considerable homology to the gamma-subunit and to phospholemman (plm) was identified in purified na, ... | 2000 | 10961995 |
| 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 |
| computer-assisted evaluation of isoelectric focusing patterns in electrophoretic gels: identification of smoothhounds (mustelus mustelus, mustelus asterias) and comparison with lower value shark species. | in this work, the most commercially important selachian species, smoothhound (mustelus mustelus) and starry smoothhound (mustelus asterias), have been identified by polyacrylamide isoelectric focusing (ief-page), along with several shark species of minor commercial value. in italy, these two smoothhound species are commonly subjected to fraudulent substitution with lesser valued sharks. after the electrophoretic runs, the band patterns of the two mustelus species were compared with those of dogf ... | 2001 | 11386666 |
| a phase i and pharmacokinetic study of squalamine, a novel antiangiogenic agent, in patients with advanced cancers. | a phase i study of squalamine, a novel antiangiogenic agent originally isolated from the dogfish shark squalus acanthias, was conducted in patients with advanced cancers to: (a) determine the maximum tolerated dose (mtd), dose-limiting toxicity (dlt) and pharmacokinetics of squalamine lactate when given as a 120-h continuous i.v. infusion every two weeks; and (b) to obtain information on prolonged (>120-h) continuous i.v. infusions in patients who have tolerated 120-h infusions. | 2001 | 11751482 |
| localization of mg2+-sensing shark kidney calcium receptor skcar in kidney of spiny dogfish, squalus acanthias. | we recently cloned a homologue of the bovine parathyroid calcium receptor from the kidney of a spiny dogfish (squalus acanthias) and termed this new protein skcar. skcar senses alterations in extracellular mg2+ after its expression in human embryonic kidney cells (nearing j, betka m, quinn s, hentschel h, elger m, baum m, bai m, chattopadyhay n, brown e, hebert s, and harris hw. proc natl acad. sci usa 99: 9231-9236, 2002). in this report, we used light and electron microscopic immunocytochemica ... | 2003 | 12759228 |
| a spermine-coupled cholesterol metabolite from the shark with potent appetite suppressant and antidiabetic properties. | we describe the pharmacological properties of a novel spermine-cholesterol adduct, msi 1436 (3beta-n-1(spermine)-7alpha, 24r-dihydroxy-5alpha-cholestane 24-sulfate), which causes reversible suppression of food and fluid intake in mammals resulting in profound weight loss, not associated with other signs or symptoms of illness, and which exhibits antidiabetic properties in genetically obese mice. | 2001 | 11360152 |
| 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 |
| texas red transport across rat and dogfish shark (squalus acanthias) choroid plexus. | confocal microscopy and image analysis were used to compare driving forces, specificity, and regulation of transport of the fluorescent organic anion, texas red (sulforhodamine 101 free acid; tr), in lateral choroid plexus (cp) isolated from rat and an evolutionarily ancient vertebrate, dogfish shark (squalus acanthias). cp from both species exhibited concentrative, specific, and metabolism-dependent tr transport from bath to subepithelial/vascular space; at steady state, tr accumulation in vasc ... | 2008 | 18650317 |
| 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 |
| beta-adrenergic regulation of a novel isoform of ncx: sequence and expression of shark heart ncx in human kidney cells. | the function, regulation, and molecular structure of the cardiac na(+)/ca(2+) exchangers (ncxs) vary significantly among vertebrates. we previously reported that beta-adrenergic suppression of amphibian cardiac ncx1.1 is associated with specific molecular motifs. here we investigated the bimodal, camp-dependent regulation of spiny dogfish shark (squalus acanthias) cardiac ncx, exploring the effects of molecular structure, host cell environment, and ionic milieu. the shark cardiac ncx sequence (g ... | 2009 | 19395557 |
| 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 |
| 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 |
| polyvalent cation receptor proteins (cars) are salinity sensors in fish. | to determine whether calcium polyvalent cation-sensing receptors (cars) are salinity sensors in fish, we used a homology-based cloning strategy to isolate a 4.1-kb cdna encoding a 1,027-aa dogfish shark (squalus acanthias) kidney car. expression studies in human embryonic kidney cells reveal that shark kidney senses combinations of ca(2+), mg(2+), and na(+) ions at concentrations present in seawater and kidney tubules. shark kidney is expressed in multiple shark osmoregulatory organs, including ... | 2002 | 12093923 |
| 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 |
| an acid-sensing ion channel from shark (squalus acanthias) mediates transient and sustained responses to protons. | acid-sensing ion channels (asics) are proton-gated na(+) channels. they are implicated in synaptic transmission, detection of painful acidosis, and possibly sour taste. the typical asic current is a transient, completely desensitizing current that can be blocked by the diuretic amiloride. asics are present in chordates but are absent in other animals. they have been cloned from urochordates, jawless vertebrates, cartilaginous shark and bony fish, from chicken and different mammals. strikingly, a ... | 2010 | 20064854 |
| multidrug resistance-associated protein 3 (mrp3/abcc3/moat-d) is expressed in the sae squalus acanthias shark embryo-derived cell line. | the multidrug resistance-associated protein 3 (mrp3/mrp3) is a member of the atp-binding cassette (abc) protein family of membrane transporters and related proteins that act on a variety of xenobiotic and anionic molecules to transfer these substrates in an atp-dependent manner. in recent years, useful comparative information regarding evolutionarily conserved structure and transport functions of these proteins has accrued through the use of primitive marine animals such as cartilaginous fish. u ... | 2007 | 18284333 |
| Squalamine as a broad-spectrum systemic antiviral agent with therapeutic potential. | Antiviral compounds that increase the resistance of host tissues represent an attractive class of therapeutic. Here, we show that squalamine, a compound previously isolated from the tissues of the dogfish shark (Squalus acanthias) and the sea lamprey (Petromyzon marinus), exhibits broad-spectrum antiviral activity against human pathogens, which were studied in vitro as well as in vivo. Both RNA- and DNA-enveloped viruses are shown to be susceptible. The proposed mechanism involves the capacity o ... | 2011 | 21930925 |
| 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 |
| relationship between oxidizable fatty acid content and level of antioxidant glutathione peroxidases in marine fish. | biological membranes can be protected from lipid peroxidation by antioxidant enzymes including catalase (cat) and selenium-dependent glutathione peroxidases 1 and 4 (gpx1 and gpx4). unlike gpx1, gpx4 can directly detoxify lipid hydroperoxides in membranes without prior action of phospholipase a(2). we hypothesized that (1) gpx4 is enhanced in species that contain elevated levels of highly oxidizable polyunsaturated fatty acids (pufa) and (2) activities of antioxidant enzymes are prioritized to m ... | 2011 | 22031739 |
| fetal bovine serum simultaneously stimulates apoptosis and dna synthesis in premeiotic stages of spermatogenesis in spiny dogfish (squalus acanthias) in vitro: modulation by androgen and spermatogenic activity status. | using the simple cystic spermatogenesis in the shark testis as a model, we previously reported the relative resistance of immature spermatogonia (stem cell and early-stage spermatogonia) to apoptosis in the normal testis and after spermatoxicant exposure in vivo. apoptosis was monitored by fluorescence image analysis of living cysts, using the validated acridine orange (ao) vital staining technique. findings show that fbs simultaneously stimulates both apoptosis and [(3)h]thymidine incorporation ... | 2008 | 18392937 |
| improving the pharmacokinetic properties of biologics by fusion to an anti-hsa shark vnar domain. | advances in recombinant antibody technology and protein engineering have provided the opportunity to reduce antibodies to their smallest binding domain components and have concomitantly driven the requirement for devising strategies to increase serum half-life to optimise drug exposure, thereby increasing therapeutic efficacy. in this study, we adopted an immunization route to raise picomolar affinity shark immunoglobulin new antigen receptors (ignars) to target human serum albumin (hsa). from o ... | 2012 | 23676205 |
| levels of mercury in muscle and liver of star-spotted dogfish (mustelus manazo) from the northern region of japan: a comparison with spiny dogfish (squalus acanthias). | we analyzed mercury (hg) concentrations in muscle and liver samples of star-spotted dogfish (mustelus manazo) caught off the northern region of japan and compared them with those of spiny dogfish (squalus acanthias) caught in the same region. the average body length of male star-spotted dogfish specimens was significantly smaller than that of female specimens, reflecting the slower growth rate of male fish. hg concentrations in liver and muscle increased with increases in body length and estimat ... | 2012 | 23271344 |
| classification of sharks in the egyptian mediterranean waters using morphological and dna barcoding approaches. | the identification of species constitutes the first basic step in phylogenetic studies, biodiversity monitoring and conservation. dna barcoding, i.e. the sequencing of a short standardized region of dna, has been proposed as a new tool for animal species identification. the present study provides an update on the composition of shark in the egyptian mediterranean waters off alexandria, since the latest study to date was performed 30 years ago, dna barcoding was used in addition to classical taxo ... | 2011 | 22087242 |
| testicular degeneration during spermatogenesis in the blue shark, prionace glauca: nonconformity with expression as seen in the diametric testes of other carcharhinids. | the elasmobranch testis consists of spherical spermatocysts, each housing a single germ cell stage and its own clone of sertoli cells. because of the simple diametrical arrangement of cysts in maturational order, the testes of squalus acanthias, scyliorhinus canicula, and prionace glauca are classified as the diametric shark testis type. the aim of this study was to document histologically the spermatocyst composition in the blue shark stage-by-stage and to establish whether the diametric testis ... | 2011 | 21538475 |
| evolution of asynchronous motor activity in paired muscles: effects of ecology, morphology, and phylogeny. | many studies of feeding behavior have implanted electrodes unilaterally (in muscles on only one side of the head) to determine the basic motor patterns of muscles controlling the jaws. however, bilateral implantation has the potential to achieve a more comprehensive understanding of modification of the motor activity that may be occurring between the left and right sides of the head. in particular, complex processing of prey is often characterized by bilaterally asynchronous and even unilateral ... | 2008 | 21669790 |
| indirect evidence for enhancement of na-k-atpase activity with stimulation of rectal gland secretion. | the relation between active chloride secretion and na-k-atpase activity was studied in the isolated perfused rectal gland of squalus acanthias stimulated by camp and theophylline. ouabain inhibited both secretion and oxygen uptake in stimulated glands. stimulation of chloride secretion by camp and theophylline resulted in a six- to sevenfold rise in ouabain-inhibitable oxygen consumption. intracellular sodium concentration decreased while intracellular potassium rose. these findings suggest acti ... | 1997 | 229737 |
| regulation of spermatogenesis: the shark testis model. | spermatogenesis is a unique developmental sequence dependent on fsh and androgen. due to the complex organization of the mammalian testis, however, mechanistic details of regulation are largely unknown. using the dogfish shark (squalus acanthias) in which there is a cystic mode of spermatogenesis and a topographic separation of different germ cell stages within the testis, we have obtained new information of general relevance on stage-related biochemical and morphological changes and have propos ... | 2008 | 2575650 |
| purification and molecular properties of the (sodium + potassium)-adenosinetriphosphatase and reconstitution of coupled sodium and potassium transport in phospholipid vesicles containing purified enzyme. | recent work in our laboratory on the purification and characterization of the (sodium + potassium)-activated adenosinetriphosphatase (nak atpase) has been reviewed. two enzymes have been purified, that from the rectal salt gland of the spiny dogfish, squalus acanthias and that from the electric organ of the electric eel, electrophorus electricus. the enzyme appears to consist of two catalytic subunits of molecular weight of about 95,000 and one glycoprotein with a molecular weight of about 50,00 ... | 2002 | 127829 |
| active potassium transport coupled to active sodium transport in vesicles reconstituted from purified sodium and potassium ion-activated adenosine triphosphatase from the rectal gland of squalus acanthias. | vesicles containing a purified shark rectal gland (sodium + potassium)-activated adenosine triphosphatase-(nak atpase) were prepared by dialyzing for 2 days egg lecithin, cholate, and the nak atpase purified from the rectal gland of squalus acanthias. these vesicles were capable of both na+ and k+ transport. studies of k+ transport were made by measuring the atp-stimulated transport outward of 42k+ or 86rb+. vesicles were preloaded with isotope by equilibration at 4 degrees for 1 to 3 days. tran ... | 2001 | 125752 |
| studies on peptides. lxxv. synthesis of the hexadecapeptide corresponding to the entire amino acid sequence of beta-melanocyte-stimulating hormone from the dogfish (squalus acanthias). | | 2000 | 305829 |
| a simple procedure for the preparation of highly purified (sodium + potassium) adenosinetriphosphatase from the rectal salt gland of squalus acanthias and the electric organ of electrophorus electricus. | | 2003 | 148851 |
| in vitro steroid secretion by staged spermatocysts (sertoli/germ cell units) of dogfish (squalus acanthias) testis. | using the dogfish shark (squalus acanthias) testis model in which different germ cell stages are topographically separated, we previously observed that steroidogenic enzyme activities vary qualitatively and quantitatively during spermatogenesis. to determine whether these data, obtained by radiolabeled tracer analysis of testicular microsomes, accurately predict steroid secretion by intact cultured spermatocysts (germ cell/sertoli cell units), steroids were radioimmunoassayed directly in spent m ... | 2006 | 1426959 |
| eye lens aging in the spiny dogfish (squalus acanthias) i. age determination from lens weight. | measurements were made of lens wet weight, body length and spine diameter of male and female spiny dogfish squalus acanthias. age was estimated from body length and spine diameter. it appears that the dogfish eye lens grows continuously during life. relationships were established between lens weight and age, which allow minimal age to be estimated from lens weight. | 2009 | 2791619 |
| biosynthesis of triacylglycerols in dogfish (squalus acanthias) liver: incorporation of (1- 14 c) palmitic acid into acyl chains. | | 2015 | 4653157 |
| the blood to tissue distribution of various polar materials in the dogfish, squalus acanthias. | | 2015 | 4402708 |
| sperm storage in male elasmobranchs: a description and survey. | two basic types of spermatozoan aggregates, spermatophores and spermatozeugmata, found in 14 different species of sharks, one species of skate, and one species of chimaera (holocephalan), were investigated using light and scanning electron microscopy. spermatophores, aggregates (usually 1,000-6,000 microns in diameter and larger) of randomly clumped sperm embedded in and surrounded by an eosinophilic matrix, were found in alopias superciliosus, odontaspis taurus, carcharodon carcharias, isurus o ... | 1994 | 8169955 |
| immunohistochemical localization of bioactive peptides and amines associated with the chromaffin tissue of five species of fish. | biogenic peptides and amines associated with the chromaffin tissue in atlantic cod (gadus morhua), rainbow trout (oncorhynchus mykiss), european eel (anguilla anguilla), spiny dogfish (squalus acanthias) and atlantic hagfish (myxine glutinosa) were identified utilizing immunohistochemical techniques. within the posterior cardinal vein (pcv) in cod, trout and eel, a subpopulation of chromaffin cells displayed immunoreactivity to tyrosine hydroxylase (th) and dopamine-beta-hydroxylase (d beta h) b ... | 1995 | 7606765 |
| the branching of insulin-like growth factor 1 and insulin: an immunohistochemical analysis during phylogeny. | the co-existence of insulin-like growth factor 1 (igf-1) with the classical islet hormones insulin (ins), glucagon (gluc), somatostatin (som) and pancreatic polypeptide (pp) in the endocrine pancreas of representative species of cyclostomes (myxine glutinosa), cartilaginous fish (raja clavata, squalus acanthias) and bony fish (cottus scorpius, carassius auratus, cyprinus carpio, anguilla anguilla) was studied by the use of monoclonal and polyclonal antisera and the double immunofluorescence tech ... | 1993 | 8265818 |
| 28s and 18s rdna sequences support the monophyly of lampreys and hagfishes. | resolving the interrelationships of three major extant lineages of vertebrates (hagfishes, lampreys, and gnathostomes) is a particularly important issue in evolution, because the basal resolution critically influences our understanding of primitive vertebrate characters. a consensus has emerged over the last 20 years that lampreys are the sister group to the gnathostomes and the hagfishes represent an ancient, basal lineage. this hypothesis has essentially displaced the classical hypothesis of m ... | 1998 | 9866205 |
| the origin of the mammalian form of gnrh in primitive fishes. | the presence of neuroendocrine hormones in extant agnathan fishes suggests that a method of control involving these hormones was operating 500-600 million years ago in emerging vertebrates. data on a limited number of species show that several members of the gnrh family of peptides may have arisen in non-teleost fishes. lamprey (petromyzon marinus) gnrh has a unique composition and has not been detected in other vertebrates. it is not yet clear whether the chicken ii gnrh-like molecule arose in ... | 1989 | 24221758 |
| potassium conductance in müller cells of fish. | the distribution of potassium conductance across the surface of retinal glial (müller) cells was determined in three species of fishes: two teleosts, the goldfish (carassius auratus) and the alewife (alosa pseudoharengus), and an elasmobranch, the spiny dogfish (squalus acanthias). potassium conductance was measured by monitoring cell depolarizations evoked by focal ejections of a 15 meq/l k+ solution onto the surface of freshly dissociated cells. the k+ conductance distributions observed in the ... | 1988 | 2467883 |
| at least one thalamotelencephalic pathway in cartilaginous fishes projects to the medial pallium. | injections of horseradish peroxidase into the medial pallium of the spiny dogfish, squalus acanthias, retrogradely labeled cells in the superficial portion of the dorsal pallium, the medial pallium and the septal area of the telencephalon, and in the posterior tubercle and posterior lateral thalamic nucleus of the diencephalon. except for the septal projection, all projections to the medial pallium are bilateral. labeled fibers could be traced from the injection site to caudal telencephalic leve ... | 2013 | 3627563 |
| localization of ouabain-sensitive, potassium-dependent nitrophenyl phosphatase in the rectal gland of the spiny dogfish, squalus acanthias. | tissue from the digitiform rectal gland of the spiny dogfish, squalus acanthias, was fixed briefly by formaldehyde perfusion and studied for the specificity and localization of p-nitrophenyl phosphatase (npp'ase) activity. the enzymatic activity was k+-dependent (56%) and ouabain-sensitive (67%-inhibition). the electron-dense reaction product (srpo4) of the cytochemical reaction (ernst, 1972b) was localized along the inner surfaces of the basolateral membranes of the secretory cells. it was abse ... | 2003 | 187344 |
| functional expression of squalus acanthias melanocortin-5 receptor in cho cells: ligand selectivity and interaction with mrap. | the melanocortin-5 receptor (mc(5)) of the dogfish squalus acanthias (sacmc(5) receptor) can be functionally expressed in cho cells in the absence of the co-expression of an exogenous mrap cdna. both human acth(1-24) and dogfish acth(1-25) were much better stimulators of the sacmc(5) receptor than any of the mammalian or dogfish msh ligands that were tested. the order of ligand selectivity for the dogfish melanocortins was acth(1-25)>αmsh>γ-msh=δ-msh>β-msh. unlike mammalian mc(5) receptors, the ... | 2012 | 22314217 |
| spontaneous contractions in elasmobranch vessels in vitro. | isolated vessels from four elasmobranchs, yellow stingray (urolophus jamaicensis), clearnose skate (raja eglanteria), ghost shark (hydrolagus novaezelandiae), and spiny dogfish (squalus acanthias), were examined for the presence of spontaneous contractions (sc). sc were observed in otherwise unstimulated dorsal aortas (da) from stingray and ghost shark, but not in skate da. unstimulated ventral aortas (va) did not exhibit sc. after treatment of va with a contractile agonist, sc appeared in sting ... | 2000 | 10766969 |
| adenosine/nitric oxide crosstalk in the branchial circulation of squalus acanthias and anguilla anguilla. | the potent vasomodulator adenosine (ad), thanks to the interaction with by a(1) and a(2) receptors, dilates systemic, coronary and cerebral vasculatures but exert a constrictor action in several vessels of respiratory organs. recent investigations suggest that nitric oxide (no) contributes to ad effects. in fish, both no and ad induce atypical effects compared to mammals. since there is very little information on the role of no and its involvement in mediating the actions of ad in fish, we have ... | 2005 | 15979367 |
| effects of wheat germ agglutinin and concanavalin a on parameters of highly purified sodium-potassium adenosine triphosphatases from squalus acanthias and electrophorus electricus. | the effects of two lectins, wheat germ agglutinin and concanavalin a, were studied on a variety of parameters of two highly purified (na+ + k+)-atpases (atp phosphohydrolase, ec 3.6.1.3), from the rectal salt gland of squalus acanthias and from the electroplax of electrophorus electricus. both lectins agglutinated the rectal gland enzyme equally, but wheat germ agglutinin inhibited (na+ + k+)-atpase activity much more. the electroplax enzyme was only marginally agglutinated and inhibited by the ... | 1990 | 210820 |
| retinofugal pathways in fetal and adult spiny dogfish, squalus acanthias. | retinofugal pathways in fetal and adult spiny dogfish were determined by intraocular injection of [3h]proline for autoradiography. distribution and termination of the primary retinal efferents were identical in pups and adults. the retinal fibers decussate completely, except for a sparse ipsilateral projection to the caudal preoptic area. the decussating optic fibers terminate ventrally in the preoptic area and in two rostral thalamic areas, a lateral neuropil area of the dorsal thalamus and mor ... | 1999 | 83899 |
| spin-label studies on the origin of the specificity of lipid-protein interactions in na+,k+-atpase membranes from squalus acanthias. | the ph dependence and salt dependence of the lipid-protein interactions of phosphatidic acid, phosphatidylserine, and stearic acid with na+,k+-atpase membranes from squalus acanthias have been studied with spin-label electron spin resonance spectroscopy, using lipids with nitroxide labels on the 14-position c atom of the sn-2 chain. for phosphatidic acid and stearic acid, the fraction of motionally restricted spin-label increases with increasing ph, with pka's of 6.6 and 8.0, respectively. in co ... | 2010 | 2994712 |
| novel spin-labels for the study of lipid-protein interactions. application to (na+, k+)-atpase membranes. | the interactions of a series of spin-labeled fatty acids, in which the nitroxide ring is incorporated in different ways as an integral part of the hydrocarbon chain, with the (na+,k+)-atpase in membranes from squalus acanthias, have been studied by electron spin resonance spectroscopy. the fatty acids are 2,4-, 2,5-, and 3,2-substituents of 2,2,5,5-tetramethylpyrrolidine-n-oxyl and belong to the class of minimal perturbation nitroxide probes. for all five fatty acid labels, a motionally restrict ... | 2010 | 2843220 |
| vibrio species associated with mortality of sharks held in captivity. | two urease-positivevibrio spp. were isolated from a brown shark (carcharhinus plumbeus) that died in captivity at a national aquarium. morphological, biochemical, and molecular genetic studies revealed one of the isolates to bev. damsela; the other isolate was unique and has been classified asv. carchariae sp. nov. bothv. damsela andv. carchariae were found to be virulent for spiny dogfish (squalus acanthias), causing death in less than 18 hours after intraperitoneal injection of ca. 4×10(6) cel ... | 1984 | 24221148 |
| trophic interactions and distribution of some squaliforme sharks, including new diet descriptions for deania calcea and squalus acanthias. | squaliforme sharks are a common but relatively vulnerable bycatch in many deep water fisheries. eleven species of squaliforme shark are commonly caught at depths of 200-1200 m on chatham rise, new zealand, and their diversity suggests they might occupy different niches. the diets of 133 deania calcea and 295 squalus acanthias were determined from examination of stomach contents. the diet of d. calcea was characterised by mesopelagic fishes, and s. acanthias by benthic to pelagic fishes, but was ... | 2013 | 23536896 |
| value of organoids from comparative epithelia models. | organoids have tremendous therapeutic potential. they were recently defined as a collection of organ-specific cell types, which self-organize through cell-sorting, develop from stem cells, and perform an organ specific function. the ability to study organoid development and growth in culture and manipulate their genetic makeup makes them particularly suitable for studying development, disease, and drug efficacy. organoids show great promise in personalized medicine. from a single patient biopsy, ... | 2015 | 26604860 |
| seasonal dynamics of the cestode fauna in spiny dogfish, squalus acanthias (squaliformes: squalidae). | this study furthers understanding of cestode infections in a marine environment through time and space by following seasonal fluctuations in infection parameters of three cestode species (gilquinia squali, trilocularia gracilis and phyllobothrium squali) parasitizing spiny dogfish (squalus acanthias) in the northwest atlantic and comparing them to work previously published from the northeast atlantic on t. gracilis. for each cestode species, host size, season and presence of the other cestode sp ... | 2014 | 24569058 |
| data for amino acid alignment of japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of japanese stingray melanocortin receptors. | this article contains structure and pharmacological characteristics of melanocortin receptors (mcrs) related to research published in "characterization of melanocortin receptors from stingray dasyatis akajei, a cartilaginous fish" (takahashi et al., 2016) [1]. the amino acid sequences of the stingray, d. akajei, mc1r, mc2r, mc3r, mc4r, and mc5r were aligned with the corresponding melanocortin receptor sequences from the elephant shark, callorhinchus milii, the dogfish, squalus acanthias, the gol ... | 2016 | 27408924 |
| [composition of the carbohydrate component and fatty acids of the chief gangliosides of the brains of cartilaginous fish]. | ganglioside composition has been studied in the brain of 5 elasmobranch fishes (3 sharks: carcharhinus longimanus, carcharhinus sp., squalus acanthias and 2 rays: dasyatis pastinaca, raja clavata). for the identification of ganglioside fractions, molar ratio of glucose, galactose, nana and sphingosine as well as the presence of hexosamine were determined in the main gangliosides from the brain of the shark c. longimanus. the data obtained indicate that the majority of brain gangliosides in elasm ... | 2008 | 941546 |
| mechanical properties of the hyomandibula in four shark species. | sharks have cartilaginous elements that support the jaws and are subjected to variable loads. the aim of this study was to understand how these elements, the hyomandibulae, respond to compressive loads, and to describe the structural level mechanical properties of mineralized cartilage. mechanical stiffness and effective poisson's ratio of the hyomandibular cartilage were measured in four species of sharks (white-spotted bamboo, chiloscyllium plagiosum; spiny dogfish, squalus acanthias; sandbar, ... | 2015 | 25376603 |
| spectral sensitivity, luminous sensitivity, and temporal resolution of the visual systems in three sympatric temperate coastal shark species. | we used electroretinography (erg) to determine spectral and luminous sensitivities, and the temporal resolution (flicker fusion frequency, fff) in three sympatric (but phylogenetically distant) coastal shark species: carcharhinus plumbeus (sandbar shark), mustelus canis (smooth dogfish), and squalus acanthias (spiny dogfish). spectral sensitivities were similar (range ~400-600 nm, peak sensitivity ~470 nm), with a high likelihood of rod/cone dichromacy enhancing contrast discrimination. spiny do ... | 2014 | 25319537 |
| heterogeneity of gamma-crystallins from spiny dogfish (squalus acanthias) eye lens. | mammalian lenses contain multiple gamma-crystallin gene products, which are differentially synthesized during lens development. we now report the isolation and characterization of multiple gamma-crystallins from lenses of adult spiny dogfish (squalus acanthias) aged about 20-30 years. about 50% of total lens protein solubilized in 50 mm phosphate, ph 7.0; about 25% of this soluble fraction consists of gamma-crystallins as determined by gel filtration. these gamma-crystallins appear homogeneous w ... | 1988 | 3342835 |
| immunohistochemical localization of urotensin i/corticotropin-releasing factor, urotensin ii, and serotonin immunoreactivities in the caudal spinal cord of nonteleost fishes. | neurosecretory cells in the caudal spinal cord of fishes were first discovered in elasmobranches. however, most of the subsequent work on the caudal neurosecretory system has emphasized its morphology and function in teleosts. two major peptides, urotensins i and ii (ui and uii), have been isolated from this system in teleosts and their amino acid sequences have been determined. we have used immunohistochemical techniques to confirm and expand previous morphological and pharmacological findings ... | 1986 | 3525617 |
| elasmobranch rectal gland cell: autoradiographic localization of [3h]ouabain-sensitive na, k-atpase in rectal gland of dogfish, squalus acanthias. | specific binding of radiolabeled inhibitor was employed to localize the na-pump sites (na,k-atpase) in rectal gland epithelium, a nacl-secreting osmoregulatory tissue which is particularly rich in pump sites. slices of gland tissue from spiny dogfish were incubated in suitable [3h]ouabain-containing media and then prepared for na,k-atpase assay, measurement of radiolabel binding, or quantitative freeze-dry autoradiography at the light microscope level. gross freezing or drying artifacts were exc ... | 1996 | 229110 |
| properties and function of kcnq1 k+ channels isolated from the rectal gland of squalus acanthias. | kcnq1 (kvlqt1) k+ channels play an important role during electrolyte secretion in airways and colon. kcnq1 was cloned recently from nacl-secreting shark rectal glands. here we study the properties and regulation of the cloned skvlqt1 expressed in xenopus oocytes and chinese hamster ovary (cho) cells and compare the results with those obtained from in vitro perfused rectal gland tubules (rgt). the expression of skcnq1 induced voltage-dependent, delayed activated k+ currents, which were augmented ... | 2001 | 11692278 |
| medullary and mesencephalic pathways and connections of lateral line neurons of the spiny dogfish squalus acanthias. | the neuronal connections of the electrosensory dorsal and the mechanosensory medial octavolateralis nuclei of the spiny dogfish squalus acanthias were studied by horseradish peroxidase, autoradiographic and axonal degeneration methods. efferents from each nucleus, in addition to extensive commissural components, give rise to ipsilateral and contralateral lemnisci that ascend to midbrain levels and terminate among the cells of the lateral mesencephalic nucleus (lmn). within lmn, electrosensory an ... | 1988 | 3179696 |
| resolution of apical from basolateral membrane of shark rectal gland. | membrane fractions were isolated from the rectal gland of squalus acanthias using differential centrifugation and a sucrose gradient run in the presence of 1 m kbr. using the basolateral membrane marker na+-k+-atpase, we obtained a sixfold purification with the most highly purified fraction from the gradient (sp act = 336 +/- 37 mumol x mg protein-1 x h-1). electrogenic br- transport was used as a marker activity of the apical membrane, which enabled the identification and purification of a memb ... | 1986 | 3022592 |
| mitochondrial and peroxisomal fatty acid oxidation in elasmobranchs. | in heart and red muscle of dogfish (squalus acanthias), the maximal activities of the fatty acid catabolizing enzyme carnitine palmitoyltransferase (cpt) are less than 5% the rate in the same tissues of teleosts (carp, cyprinus carpio; trout, salmo gairdneri). cpt activities in these tissues of hagfish (eptatretus stouti) are approximately 10% the rate in teleosts. however, the maximal activities of the beta-oxidation enzyme beta-hydroxyacyl-coa dehydrogenase (hoad) in dogfish red muscle and hea ... | 1990 | 2316720 |
| urea tolerance of myofibrillar proteins of two elasmobranchs: squalus acanthias and raja tengu. | some biochemical properties of actomyosin and myosin from elasmobranchs, squalus acanthias and raja tengu are compared with those of a freshwater (cyprinus carpio) and a marine teleost (seriola quinquiradiata). whereas ca2+-atpase of teleost actomyosins are more stable in the absence of urea, the reverse is true for elasmobranchs up to 1.0 m urea. in contrast to that of teleosts, the mg2+-atpase of s. acanthias actomyosin shows an activation in the presence of urea, where as that of r. tengu per ... | 1986 | 2434054 |
| neuropeptide control of the cardiovascular system in fish and reptiles. | accumulating evidence shows the involvement of neuropeptides in cardiovascular control in mammals as well as non-mammalian species. our own immunohistochemical studies indicate a sparse innervation only in cyclostomes, holostean fish and lungfish, a more extensive variation and distribution in elasmobranchs and teleosts, and a rich and varied innervation of the cardiovascular system in crocodiles and lizards. vasoactive intestinal polypeptide (vip), neuropeptie y (npy), gastrin releasing peptide ... | 2016 | 8728849 |
| freeze-fracture and morphometric analysis of occluding junctions in rectal glands of elasmobranch fish. | the structure of occluding junctions in secretory and ductal epithelium of salt-secreting rectal glands from two species of elasmobranch fish, the spiny dogfish squalus acanthias and the stingray dasyatis sabina, was examined by thin-section and freeze-fracture electron microscopy. in both species, occluding junctions between secretory cells are shallow in their apical to basal extent and are characterized by closely juxtaposed parallel strands. average strand number in the dogfish was 3.5 +/- 0 ... | 1981 | 6260950 |
| contractile properties of the elasmobranch rectal gland. | the importance of the rectal gland in elasmobranch osmoregulation is well established. the rate of secretion by the gland is under the control of a variety of secretagogues and inhibitors. early morphological work suggested that a band of smooth muscle cells surrounds the periphery of the shark rectal gland between the secretory tubules and the connective tissue capsule. to confirm the presence of the muscle ring, we examined histological sections from two species of shark, squalus acanthias and ... | 2001 | 11104711 |
| the putative mechanism of na(+) absorption in euryhaline elasmobranchs exists in the gills of a stenohaline marine elasmobranch, squalus acanthias. | we recently cloned an nhe3 orthologue from the gills of the euryhaline atlantic stingray (dasyatis sabina), and generated a stingray nhe3 antibody to unequivocally localize the exchanger to the apical side of epithelial cells that are rich with na(+)/k(+)-atpase (a mrc). we also demonstrated an increase in nhe3 expression when stingrays are in fresh water, suggesting that nhe3 is responsible for active na(+) absorption. however, the vast majority of elasmobranchs are only found in marine environ ... | 2007 | 17208025 |
| glutamine synthetase isozymes in elasmobranch brain and liver tissues. | glutamine synthetase is present as isozymic forms in the elasmobranchs squalus acanthias (dogfish shark) and dasyatis sabina (stingray). subcellular fractionation of elasmobranch brain and liver tissue shows the enzyme to be predominantly cytosolic in the former tissue and mitochondrial in the latter. for the cytosolic brain enzyme, the subunit mr equals 42,000 in the stingray and 45,000 in the shark, as determined by sodium dodecyl sulfate-gel electrophoresis/western blotting. the subunit mr = ... | 1987 | 2878924 |
| immunohistochemical study of the telencephalon of the spiny dogfish, squalus acanthias. | the paucity of experimental data and the differences in telencephalic organization between sharks and other jawed vertebrates have complicated telencephalic comparisons. the distribution of neuropeptides has been extremely useful in recognizing and comparing major subdivisions of the telencephalon among vertebrates. immunohistochemical techniques were therefore used to study the distribution of substance p (sp), leucin-enkephalin (lenk), and serotonin (5ht), as well as tyrosine hydroxylase (th), ... | 1988 | 2466059 |
| the spiny dogfish (squalus cubensis/megalops group): the envenoming of a fisherman, with taxonomic and toxinological comments on the squalus genus. | the authors report a spiny dogfish (squalus cubensis/megalops group) sting of a professional fisherman. he was injured on the left hand by the spine anterior to the fish's dorsal fin and manifested local edema, erythema, and excruciating pain for 6 h. sharks of the genus squalus megalops/cubensis and squalus acanthias are found throughout the world; they have two spines in front of their dorsal fins and channels with a whitish mass containing large vacuolated cells which secrete venom. the squal ... | 2005 | 16323262 |
| phylogenetic relationships amongst chloromyxum mingazzini, 1890 (myxozoa: myxosporea), and the description of six novel species from australian elasmobranchs. | six novel species of chloromyxum mingazzini, 1890 are described using a whole evidence approach combining morphometric and molecular data, together with features of their biology. elasmobranchs were collected in australian waters, from the great barrier reef, queensland, off lizard and heron islands; from moreton bay, southeast queensland; off hobart, tasmania; and from the tamar river, launceston, tasmania. the novel species proposed here are: chloromyxum hemiscyllii n.sp. from hemiscyllium oce ... | 2012 | 22085584 |