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At least 19 recordsLinked to original sources
PubMedDate not supplied

Neuropeptide Y-related peptides from the pancreas of a teleostean (eel), holostean (bowfin) and elasmobranch (skate) fish.

Homologous peptides belonging to the pancreatic polypeptide (PP) family were isolated from the pancreas of a teleostean fish, the American eel (Anguilla rostrata), an holostean fish, the bowfin (Amia calva) and an elasmobranch fish, the skate (Raja rhina), and their primary structures were determined. The peptides show stronger homology to neuropeptide Y, particularly in their COOH-terminal regions, than to peptide YY or pancreatic polypeptide and contain an alpha-amidated COOH-terminal tyrosine residue. The skate peptide Tyr-Pro-Pro-Lys-Pro-Glu-Asn-Pro-Gly-Asp10-Asp-Ala-Ala-Pro-Glu-Glu- Leu-Ala-Lys- Tyr20-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu30-Ile-Thr-Arg- Gln-Arg-Tyr-NH2 represents the first member of the PP family to be isolated from a cartilaginous fish. The primary structure of the pancreatic PP family peptide has been more strongly conserved among the phylogenetically more ancient holostean and elasmobranch fishes than among the teleosts. A comparison of the primary structures of all PP family peptides supports the hypothesis and evolution has acted to conserve features of tertiiary structure in the molecules (e.g., the polyproline- and alpha-helices) rather than individual amino acid residues.

Amino Acid Sequence↗
PubMed1984

A second class of immunoglobulin other than IgM present in the serum of a cartilaginous fish, the skate, Raja kenojei: isolation and characterization.

A second class of immunoglobulin, in addition to a pentameric immunoglobulin analogous to mammalian IgM, was found in the serum of a cartilaginous fish, the skate, Raja kenojei. The immunoglobulin was a non-covalently associated dimer with a sedimentation coefficient of 8.9S and a mol. wt of 320,000. Its heavy chain had a mol. wt of 45,000-50,000, smaller than that of the heavy chain (mol. wt 70,000) of the skate IgM, and had its own specific antigenic determinants. The immunoglobulin was synthesized in plasma cells different from those that produced the IgM. These results provide evidence that, contrary to the prevailing view, the divergence of immunoglobulin class occurred as early in evolution as the cartilaginous fish, a primitive vertebrate.

Animals↗
PubMed2000

Novel polysialogangliosides of skate brain structural determination of tetra, penta and hexasialogangliosides with a NeuAc-GalNAc linkage.

The gangliosides in the brain of a cartilaginous fish, skate (Bathyraja smirnovi), have been isolated and characterized by means of methylation analysis, antibody binding, enzymatic hydrolysis and MALDI-TOF MS. In addition to gangliosides with known structures (GM2, fucosyl-GM1, GD3, GD2, GT3 and GT2), five polysialogangliosides were isolated and characterized as having the following structures. (1) IV3NeuAc, III6NeuAc, II3NeuAc-Gg4Cer; (2) IV3NeuAc2, III6NeuAc, II3NeuAc-Gg4Cer; (3) IV3NeuAc, III6NeuAc, II3NeuAc2-Gg4Cer; (4) IV3NeuAc, III6NeuAc, II3NeuAc3-Gg4Cer; and (5) IV3NeuAc2, III6NeuAc, II3NeuAc3-Gg4Cer. These structures are 'hybrid-type' which comprise combinations of alpha-series and either a, b or c-series structures. Three gangliosides (2), (4) and (5), were novel. The main features of the ganglioside composition of skate brain were an abundance of gangliotriaosyl species, a lack of gangliotetraosyl species (except fucosyl-GM1), and an abundance of hybrid-types. These characteristics closely resemble those in shark brain which we reported previously [Nakamura, K., Tamai, Y. & Kasama, T. (1997) Neurochem. Int. 30, 593-604]. Two of the hybrid-type gangliosides (1) and (4), were examined for their neuritogenic activity toward cultured neuronal cells (Neuro-2A), and were found to have more potent activity than nonhybrid-type gangliosides such as GM1.

Acetylgalactosamine↗
PubMedDate not supplied

[Free amino acids in the central nervous system of skates (Batomorpha)].

The distribution of free amino acids in strongly and weakly electric fishes (skates and rays) varies in relation to species, brain region and functional peculiarities. In comparison to the weakly electric fishes (Raja clavata and Myliobatis aquila) a number of brain regions of the strongly electric species (Torpedo marmorata and T. ocellata) show considerably higher concentrations of arginine, glycine and tyrosine, and lower concentrations of aspartic acid. The electric organ of the strongly electric fishes was characterized by the lack of tyrosine and glycine, by traces of GABA, and by considerably higher concentrations of alanine, serine, cysteine, and histidine than in the brain of the same species. The electromotor center Lobus electricus of the stronlgy electric fishes, in contrast to other brain regions, shows exceptionally high concentrations of tyrosine and alanine. In comparison to the mammalian brain, levels of brain alanine, glycine, cysteine and cystine are higher in the four fish species studied. The results are discussed in relation to the morphophysiological organization of the fish central nervous system and of the mechanisms of electrogenesis.

Amino Acids↗
PubMed1986

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 cumulative excretion (as a % of dose) was 0.44 +/- 0.10 (n = 4, +/- SD), 0.71 +/- 0.23 (n = 6), and 1.00 +/- 0.34(n = 4) for doses of 1, 5, and 20 mumol/kg, respectively, while the shark excreted only 0.15 +/- 0.15% (n = 8) at a dose of 5 mumol/kg. As in mammals, the availability of hepatic and biliary glutathione was a determinant of the biliary excretion of methyl mercury in these species: the administration of sulfobromophthalein, a compound known to inhibit both glutathione and methyl mercury excretion in rats, or of L-buthionine-S,R-sulfoximine, an inhibitor of glutathione biosynthesis, decreased the biliary excretion of both glutathione and mercury in the skate. The slow hepatic excretory process for methyl mercury in the skate and shark was attributed to an inordinately slow rate of bile formation: from 1 to 4 ml/kg X day. An inefficient biliary excretory process in fish may account in part for the long biological half-times for methyl mercury in marine species.

Animals↗
PubMed1976

A comparative study of the glycolipids of human, bird and fish testes and of human sperm.

The glycolipids of human testis and sperm have been compared. Both adult testis and the sperm exhibited remarkably complex, but generally similar, patterns of glycolipids. In particular, both contained appreciable amounts of the sulfogalactosylmonoalkylmonoacylglycerol, recently shown to be the principal glycolipid of the testis and sperm of a number of animals. In contrast, immature (prebuteral) human testis did not contain this compound. To extend knowledge on the possible distribution of sulfogalactosylmonoalkylmonoacylglycerol in the testes of other chordates, we have also analysed the glycolipids of the testes of a number of birds and fish. None of the testes from these species contained the above compound. Instead, sulfogalactosylceramide was found to be a major glycolipid of the testis of mature fowl, duck and skate-fish and sulfogalactosylglucosylceramide of the testis of mature salmon and trout. Immature duck testis contained only a trace of sulfogalactosylceramide. These studies reveal intriguing differences between the sulfatides of various chordates, lend support to the concept that sulfatides increase markedly in testis at a specific stage of spermatogenesis and suggest an important role for sulfatides in testicular and spermatozoal function.

Adult↗
PubMed2000

Organic and inorganic arsenic and lead in fish from the South Adriatic Sea, Italy.

Total, organic and inorganic arsenic and lead were measured from the muscle of different kinds of fish: skate (Raje spp.), hake (Merluccius merluccius) and blue whiting (Micromesistius poutassou), caught in the South Adriatic Sea (South Italy) in the period June-August 1995. The highest levels of total arsenic were found in skate (Raje spp.) whose values ranged from 14.4 to 61.5 mg/kg ww, followed by blue whiting (M. poutassou) and hake (M. merluccius) that showed lower levels ranging from 8.5 to 21.5 mg/kg ww and from 5.9 to 16.1 mg/kg ww, respectively. In all the species examined most of this element was present as organic compounds while inorganic arsenic was only a very modest percentage (0.47-3.5%) of the total arsenic present. Lead in all species analysed was at small concentrations with mean values ranging from 0.12 to 0.15 mg/kg ww. According to the rules in force in Italy no samples showed concentrations of lead exceeding the peak value of 2 mg/kg.

Animals↗
PubMed1990

A partial solution to the homonym problem: parents' linguistic input to young children.

During early word learning, children may assume a unique form-meaning relationship: that a unique form corresponds to each meaning (Clark, 1987) and vice versa (Slobin, 1985). Homonyms appear to violate this one-to-one mapping, and therefore might prove problematic; for example, all things labeled bat might be put into the odd category 'things that fly and are used to play ball.' We asked whether parents' descriptions of homonyms to their young children provide linguistic information that could help children to differentiate conceptually and linguistically these cases. Fifteen parents described pictured sets of concrete object homonyms and categorically related objects to their young children. Parents described homonyms by using explicit statements of category inclusion, subordinate forms (compounds, e.g., kiwi-bird), and specific forms that flagged the unusual homonym relationship. Parents especially provided distinctive alternating forms for homonym pairs (e.g., iceskate vs. skate-fish) suggesting that they were attempting to preserve the unique form-meaning relationship violated by homonyms. We discuss how such linguistic information might be used by children to differentiate homonyms.

Child, Preschool↗
PubMed1999

Functional morphology of undulatory pectoral fin locomotion in the stingray taeniura lymma (Chondrichthyes: dasyatidae)

Rajiform locomotion is a unique swimming style found in the batoid fishes (skates and rays) in which thrust is generated by undulatory waves passing down the enlarged pectoral fins. We examined the kinematic patterns of fin motion and the motor patterns of pectoral fin muscles driving the locomotor system in the blue-spot stingray Taeniura lymma. Our goals in this study were to determine overall patterns of fin motion and motor control during undulatory locomotion, to discover how these patterns change with swimming velocity and to correlate muscle function with kinematics and pectoral morphology. Kinematic data were recorded from five individuals over a range of swimming speeds from 22 to 55 cm s(-)(1) (0.9-3.0 DL s(-)(1), where DL is body disc length). Electromyographic (EMG) data were recorded from three individuals over a range of velocities (1.2-3.0 DL s(-)(1)) at seven locations (four dorsal, three ventral) along the pectoral fin. As swimming velocity increases, fin-beat frequency, wavespeed and stride length increase, number of waves and reduced frequency decrease and fin amplitude remains constant. There is variability among individuals in frequency and amplitude at a given speed. An inverse relationship was found in which a high fin-beat frequency is associated with a low fin amplitude and a low fin-beat frequency is associated with a high fin amplitude. The motor pattern of undulatory locomotion is alternate firing activity in the dorsal and ventral muscles as the wave moves along the fin from anterior to posterior. Fin muscles are active along the entire length of the fin except at the lowest speeds. As swimming velocity and fin-beat frequency increase, the time of activation of posterior muscles becomes earlier relative to the onset of activity in the anterior dorsal muscles. The duration of muscle activity is longer in the ventral muscles than in the dorsal muscles, indicating that they play a central role in the power stroke of the fin-beat cycle. The anterior muscles (dorsal and ventral) are active for a relatively longer part of the stride cycle than the posterior muscles. Both the anterior position and the large duty factor of the anterior muscles reflect the role of these muscles in initial wave generation. Synchronous recordings of kinematic data with EMG data reveal that the anterior dorsal and middle ventral muscles do mostly positive work, whereas the dorsal and ventral posterior muscles do negative work at most swimming speeds.

Journal Article↗
PubMed2003

Species characterization of plasma nitrite/nitrate (NOx) concentration.

Experiments were designed to detect and determine differences between nitrite/nitrate concentration ([NOx]) in plasma across 15 species selected from seven classes of vertebrates. Blood collected in syringes was placed immediately into ethylenediaminetetraacetic acid (EDTA)-containing tubes and was centrifuged. Plasma [NOx] was determined by measurement of chemiluminescence. Across classes of vertebrates, baseline plasma [NOx] ranged from 0.6 to 171.3 nmol/ml. Mean +/- SD plasma [NOx] was highest in a fresh-water, jawless fish (lamprey, 95.5 +/- 9.1 nmol/ml) and lowest in a saltwater cartilaginous fish (skates, 1.1 +/- 0.4 nmol/ml). Both amphibians tested had a wide range in plasma [NOx], which was explained partly by temporal changes during the year. Within the mammalian class, plasma [NOx] ranged from 3.8 to 43.2 nmol/ml. Results of this study indicate that NO is detectable in plasma of all classes of vertebrates and that baseline concentration varies among species.

Animals↗
PubMedDate not supplied

[Effect of focused ultrasound on the electroreceptor system of skates and certain fish and amphibian tissues].

The effects of focused ultrasound have been investigated on the structures of electroreceptor system of the Black Sea skates (Raja clavata, Dasyatis pastinaca), as well as on the tissues of some other poikilotherms (fishes Belone belone and Solea lascaris, toad Bufo viridis, frog Rana temporaria). It was shown that focused ultrasound evokes excitation (onset of impulse activity) when applied to the pore of electroreceptors and inhibition of the activity when applied to the ampulla itself. The data obtained indicate that thermal conductivity of tissues in poikilotherms is lower than that in homoiotherms.

Animals↗
PubMed1996

Band 3 in cell volume regulation in fish erythrocytes.

Erythrocytes of the skate (Raja erinacea) demonstrate a regulatory volume decrease response when exposed to hypotonic stress by releasing taurine and other organic osmolytes. We review the transport characteristics, physical changes and signaling pathways of a volume-activated osmolyte channel associated with band 3 in skate red blood cells that can be distinguished from anion channels and is separate from the anion exchanger function of band 3.

Animals↗
PubMed2000

Two new species of Duplicibothrium Williams & Campbell, 1978 (Tetraphyllidea: Serendipidae) from the Pacific cownose ray Rhinoptera steindachneri.

Two new tetraphyllidean species, Duplicihothrium caircae n. sp. and D. paulum n. sp., are described from Pacific cownose rays Rhinoptera steindachneri collected from the Gulf of California. D. cairae n. sp. differs from the only other known species in this genus, D. minutum, in its possession of two posteriorly bifurcating longitudinal septa on each bothridium and having a greater number of loculi per bothridium, wider bothridia and a greater number of segments per worm. D. paulum n. sp. differs from the above two species in being shorter, having two continuous longitudinal septa on each bothridium, rather than posteriorly bifurcating or absent longitudinal septa, having a greater number of loculi per bothridium and having fewer segments per worm. The generic diagnosis of Duplicibothrium is amended to reflect the inclusion of the two new species. Species of Duplicibothrium appear to be restricted to host species of the genus Rhinoptera. Systematic information gained from the study of these two new species supports the monophyly of the tetraphyllidean family Serendipidae and suggests that Duplicibothrium shares a phylogenetic heritage with species in the genera Glyphobothrium and Serendip, taxa that are also parasitic in cownose rays. Evidence for a phylogenetic relationship between serendipid species and species of Dioecotaenia is discussed, as are potential molluscan hosts for cestode species in Duplicibothrium and Dioecotaenia.

Animals↗
PubMed2000

Emendation of the generic diagnosis of Tylocephalum (Cestoda: Lecanicephalidea: Tetragonocephalidae), and description of Tylocephalum brooksi n. sp.

A new species of Tylocephalum is described from the spiral intestine of the cownose ray Rhinoptera bonasus taken off Venezuela. Tylocephalum brooksi n. sp. is the third species described parasitizing this host species, along with T. pingue and T. bonasum. T. brooksi is similar to congeners in the possession of a scolex with a fungiform pars apicalis, craspedote segmentation, circummedullary vitellarium, external seminal vesicle, bilobed ovary, and medioventral uterus. However, this species differs from all previously described species of Tylocephalum in having a collar around the base of the pars apicalis densely covered by large digitiform processes (microtriches?), and an internal seminal vesicle. The internal seminal vesicle is a feature currently used to differentiate Tetragonocephalum from Tylocephalum. Its presence in T. brooksi indicates that it should be considered a specific instead of a generic character. An emended diagnosis of Tylocephalum is proposed excluding this feature, along with distribution of the testes in the preovarian field and circummedullary distribution of vitelline follicles. Species of Tylocephalum and Tetragonocephalum are reviewed on the basis of original descriptions, and 2 distinct morphological groups of species defined. Species of the Tetragonocephalum group possess a combination of an acraspedote strobila, segments much longer than wide, testes limited to the region anterior to the cirrus sac, vitellarium of lateral bands, conspicuously enlarged genital atrium and pore, cirrus sac dorsal to genital atrium, and bisaccate uterus. Species of the Tylocephalum group differ from Tetragonocephalum in possession of a craspedote strobila, segments more quadrangular, testes distributed throughout the preovarian field, inconspicuous genital atrium, uniformly saccate uterus, cirrus sac lateral to genital atrium, and probable circummedullary vitellaria in all species.

Animals↗
PubMed1997

Six species of Acanthobothrium (Eucestoda: Tetraphyllidea) in stingrays (Chondrichthyes: Rajiformes: Myliobatoidei) from Ecuador.

Six species of Acanthobothrium, 4 described as new, are reported in stingrays from southern Ecuador. Acanthobothrium atahualpai n. sp. in Gymnura afuerae most closely resembles Acanthobothrium fogeli and Acanthobothrium parviuncinatum by having bothridial hooks with recurved prongs and short handles. It differs from A. fogeli by having bothridial hooks 163-195 microns vs. 78-114 microns long and averaging 25 vs. 32 testes per pruglottis: it differs from A. parviuncinatum by having bothridial hooks 163-195 microns vs. 87 microns long and averaging 25 vs. 13 testes per proglottis. Acanthobothrium minusculus n. sp. in Urolophus tumbesensis most resembles Acanthobothrium campbelli and Acanthobothrium vargasi by being no more than 3 mm long and having 6-30 testes per proglottis. It can be distinguished from them by having bothridial hooks averaging 86 microns vs. 108-111 microns and 130-133 microns long, and 6-10 vs. 15-23 and 22-29 testes per proglottis, respectively. Acanthobothrium monksi n. sp. in Aetobatus narinari resembles Acanthobothrium tasajerasi from Himantura schmardae by having a prominent genital atrium and a large globose cirrus sac; it differs by averaging 21 vs. 35 testes per proglottis and having bothridial hooks averaging 150 microns vs. 165 microns long. Acanthobothrium obuncus n. sp. in Dasyatis longus resembles a group of species characterized by wider than long to square immature and mature proglottides, bothridia at least partially fused to the scolex at their posterior ends, and asymmetrical ovarian arms with aporal arms extending anteriorly to the vaginal level. It resembles Acanthobothrium americanum by averaging 73 vs. 72 testes per proglottis, but differs by having bothridial hooks averaging 120-131 microns vs. 151 microns long; it resembles Acanthobothrium chilensis by having bothridial hooks averaging 120-131 microns vs. 130 microns long, but differs by averaging 73 vs. 90 testes per proglottis. Acanthobothrium campbelli in Urotrygon chilensis and Acanthobothrium costarricense in Dasyatis longus, previously known in those hosts from the Pacific coast of Costa Rica, are reported from Ecuador for the first time.

Animals↗
PubMedDate not supplied

[The effect of pentagastrin and ornithine-tetragastrin on motor activity of the stomach in skates and scorpion-fish].

Low doses of pentagastrin (50 mug/kg b. w.) have no physiological effect on motor activity of the stomach in the skate Dasyatis pastinaca. Average doses (100-200 mug/kg) stimulate the activity, whereas high ones (300 mug/kg) inhibit the frequency of stomach contractions, slightly increasing their amplitude. Ornithine tetragastrin in a dose 2000 mug/kg does not affect motor activity of the stomach in skates. In the scorpion-fish Scorpaena porcus, ornithine tetragastrin (1000 and 2000 mug/kg) inhibits motor activity of the stomach.

Animals↗
PubMed1982

Electric and magnetic field detection in elasmobranch fishes.

Sharks, skates, and rays receive electrical information about the positions of their prey, the drift of ocean currents, and their magnetic compass headings. At sea, dogfish and blue sharks were observed to execute apparent feeding responses to dipole electric fields designed to mimic prey. In training experiments, stingrays showed the ability to orient relative to uniform electric fields similar to those produced by ocean currents. Voltage gradients of only 5 nanovolts per centimeter would elicit either behavior.

Animals↗
PubMed1998

Aryl hydrocarbon receptor function in early vertebrates: inducibility of cytochrome P450 1A in agnathan and elasmobranch fish.

The mammalian aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that controls the expression of cytochrome P450 1A (CYP1A) genes in response to halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The natural ligand and normal physiologic function of this protein are as yet unknown. One approach to understanding AHR function and significance is to determine the evolutionary history of this receptor and of processes such as CYP1A induction that are controlled by the AHR in mammals. In these studies, AHR function was evaluated in representative cartilaginous fish (little skate, Raja erinacea) and jawless fish (sea lamprey, Petromyzon marinus and Atlantic hagfish, Myxine glutinosa), using CYP1A induction as a model AHR-dependent response. Treatment of skate with beta-naphthoflavone (BNF) caused an 8-fold increase in hepatic ethoxyresorufin O-deethylase (EROD) activity as well as a 37-fold increase in the content of immunodetectable CYP1A protein. Evidence of CYP1A inducibility was also obtained for another cartilaginous fish, the smooth dogfish Mustelus canis. In contrast, hepatic EROD activity was not detected in untreated lamprey nor in lamprey treated with 3,3'4,4'-tetrachlorobiphenyl (TCB), a potent AHR agonist in teleosts. A possible CYP1A homolog was detected in lamprey hepatic microsomes by one of three antibodies to teleost CYP1A, but expression of this protein was not altered by TCB treatment. CYP1A protein and catalytic activity were measurable in hagfish, but neither was induced after treatment with TCB. These results suggest that the AHR-CYP1A signal transduction pathway is highly conserved in gnathostomes, but that there may be fundamental differences in AHR signaling or AHR-CYP1A coupling in agnathan fish. Agnathan fish such as hagfish and lamprey may be interesting model species for examining possible ancestral AHR functions not related to CYP1A regulation.

Animals↗