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PubMed1990

The effect of cadmium and other metals on vascular smooth muscle of the dogfish shark, Squalus acanthias.

The effect of Cd2+ and related metals (Ni2+, Hg2+, Pb2+, Co2+, Sn2+ Cu2+ and Zn2+) on vascular tension was studied using isolated rings of endothelium-free, smooth muscle from the ventral aorta of the shark, Squalus acanthias. Both Cd2+ and Ni2+ produced significant vasoconstriction at concentrations at or above 10(-6) M (112 and 59 ppb, respectively); the other metals were either marginally constrictive (Hg2+ and Sn2+) or were without effect (Pb2+, Co2+, Cu2+, and Zn2+). We suggest that previously published vascular effects of Hg2+ and Pb2+ may have been secondary to responses of the vascular endothelium, and that the role of Ni2+ in hypertension should be investigated further. Our data indicate that the effects of metals on this vascular smooth muscle are specific and not generic. Moreover, this system could be utilized to investigate the mechanisms of metal-induced vasoconstriction.

Animals↗
PubMed1985

Oxygen binding by the blood and hematological effects of capture stress in two big game-fish: mako shark and striped marlin.

Blood from capture-stressed striped marlin cannot be fully saturated with oxygen in the presence of lactic acid because of a substantial Root effect. Titration of blood to pH 7.6 at 25 degrees C gave an O2 affinity constant, P50 = 17 mmHg. The P50 was highly sensitive to pH showing a Bohr factor phi = delta log P50/delta pH = -0.74. Blood from capture-stressed mako sharks did not show either a Root effect or a significant Bohr effect (delta log P50/delta pH = +0.16). The O2-affinity constant, P50, was 10.6 mmHg at pH 7.6 and 25 degrees C. Hematological measurements following capture gave hematocrit values of 24.2 +/- 8.1% and 32.3 +/- 10.8% for marlin and mako respectively, and high concentrations of blood lactate in both species (15-16 mmol l-1). The O2 transport properties of the blood are discussed in relation to oxygen demand and capture stress.

Animals↗
PubMed1990

A novel angiogenic inhibitor derived from Japanese shark cartilage (I). Extraction and estimation of inhibitory activities toward tumor and embryonic angiogenesis.

Guanidine extraction and crude fractionation of Japanese shark cartilage by ultrafiltration on a molecular weight basis were conducted and the antiangiogenic activities were assayed as to the inhibitions of tumor and embryonic angiogenesis. Significant inhibition of angiogenesis was found, and there was a linear relationship between the results of the two assays. The inhibitory activities were concentrated in the fraction in the molecular weight range of 103 to 104, and were resistant to heat treatment.

Animals↗
PubMed1987

Determination of the distribution of constituent disaccharide units within the chain near the linkage region of shark-cartilage chondroitin sulfate C.

A method for analyzing the distribution of constituent disaccharide units within the chain near the linkage region of chondroitin sulfate has been developed. The method consists of (a) chemical modification of the reducing terminal residue in the polysaccharide by a 2-(2,4-dinitrophenylamino)ethylamino (DNP-AEA) group, (b) controlled fragmentation of the DNP-AEA-labeled polysaccharide with chondroitinase AC-I, followed by separation of the digestion products into the DNP-AEA-labeled fragments and unlabeled fragments on octyl-Sepharose CL-4B gel, (c) fractionation of the DNP-AEA-labeled fragments into fractions having different chain-lengths on Sephadex G-100 (superfine), and (d) determination of the disaccharide unit composition of the de-dinitropheylated products (AEA-labeled fragments) by the method combining chondroitinase AC-II treatment with HPLC analysis. A preparation of shark cartilage chondroitin sulfate C, which had been characterized well with regard to molecular species (Mr 48,000; average number of repeating disaccharide units (dpav) 93-94; consisting of chondroitin 6-sulfated 66.8%, 4-sulfated 22.5%, disulfated (D type) 10.3%, and nonsulfated units 0.4%), was analyzed by the above method. On the basis of the data obtained, distribution features of the disaccharide units within the chain near the linkage region of the polysaccharide (dpav 27) were estimated. It was, however, difficult to propose a final primary sequence of the polysaccharide chain, although there was a definite trend towards an enrichment of 4-sulfated and nonsulfated disaccharide residues in the area close to the linkage region (dpav 3-9 or 11). This was apparent together with an enrichment of 6-sulfated and disulfated disaccharide residues in the area distant from the linkage region (dpav 11 or 13-27).

Animals↗
PubMed1982

Stability of shark and human lens fiber cell membranes.

1. Scanning electron microscopy of minced dogfish, shark, and human lens fiber cell preparations showed that neither 8 M urea or 1% SDS was capable of totally disrupting the fiber cells, but that their membranes were totally disrupted by 1% SDS containing 50 mM dithiothreitol. 2. Fiber cells were purified by sucrose centrifugation and extracted with Tris-buffer, 8 M urea, 1% SDS and 50 mM dithiothreitol plus 1% SDS. 3. A residual 10% of the protein was capable of maintaining membrane integrity. 4. DTT + SDS totally dissolved the membranes, implying that disulfide bonds are involved in maintaining structure. 5. Non-tryptophan fluorescence was nearly totally extracted prior to the SDS-DTT step, indicating that the fluorescence associated with the membrane protein was not serving as crosslinks between extrinsic and intrinsic proteins. 6. Polyacrylamide slab gel electrophoresis revealed that after exhaustive extractions of lens fiber cells with Tris-buffer, 8 M urea and 1% SDS, the addition of DTT released major heat stable 27,000 and 24,000 dalton peptides. 7. The data support the concept that fiber cell membranes contain high levels of extrinsic peptides and intrinsic peptides whose stability depends strongly on oxidized crosslinks, probably disulfide bonds.

Animals↗
PubMed1982

An investigation of the co-operative binding of carbon monoxide to the haemoglobin of the carpet shark Cephaloscyllium.

1. Carpet Shark haemoglobin shows co-operative equilibrium CO binding at pH 7.0 (n = 1.8). 2. Flash photolysis shows that the T form of the protein is stabilised at low pH and in the presence of Inositol Hexaphosphate (I.H.P.). 3. At high pH the R form of the protein is stabilised and exhibits kinetic heterogeneity, assigned to different chain reactivities. 4. Stopped flow and flash photolysis under various conditions allows estimates to be made of the association and dissociation rates of CO binding for the two forms of the protein. 5. The functionality of the protein, with regard to CO binding, can be described by a modified two state model.

Allosteric Regulation↗
PubMed1983

Characterization of the non-saponifiable fraction of the liver lipids of the shark Carcharias taurus by mass-spectrometry.

1. The non-saponifiable fractions (NSF) of the liver lipids of the common Nigerian shark Carcharias taurus were identified by mass-spectrometry. 2. The lipids were extracted from the liver microsomes. 3. Hydrocarbons made up 21.29% of the NSF, sterols 26.45% and coenzymes 52.26%. 4. Thin layer chromatography followed by mass-spectral analysis showed that squalene was the major hydrocarbon present. 5. The sterol fraction consisted of cholesterol, 1-octanol and 1-hexadecyl glycerol ether. 6. The coenzymes consisted clearly of vitamin A, coenzyme Q and probably also vitamin E.

Animals↗
PubMed1990

High hemoglobin mixed disulfide content in hemolysates from stressed shark.

1. Hemolysate from heavily stressed smooth hammerhead shark, Sphyrna zygaena, shows three electrophoretic components, SZ I, SZ II and SZ III, whose relative concentrations are 36.4 +/- 6.8, 36.4 +/- 5.0 and 20.8 +/- 5.7%, respectively. After reduction with DTE only SZ I remained. 2. SZ I reacted with glutathione disulfide reconstitute SZ II and SZ III. 3. Non-reduced, DTE-reduced, and denatured hemoglobin were found to have 2.0 +/- 0.4, 3.7 +/- 0.6, and 9.4 +/- 0.7-SH groups, respectively. 4. Erythrocyte non-protein--SH (NPSH), including glutathione present as mixed disulfide with SZ II and SZ III, is 1.7 NPSH/Hb.

Adolescent↗
PubMed1992

Purification of a novel heterodimer from shark (Carcharhinus plumbeus) serum by gel-immobilized metal chromatography.

1. Resolution of the fraction of sandbar shark (Carcharhinus plumbeus) serum that was soluble in 50% saturated ammonium sulfate by gel-immobilized metal-affinity chromatography allowed the isolation of a novel disulfide-bonded heterodimer of intact mass 70 kDa. 2. Following reduction, the molecule could be resolved into two chains of apparent mass 36 and 24 kDa. 3. The molecules were glycoproteins as determined by an observed reduction in molecular weight following enzymatic glycosylation. 4. The two separate chains were related to one another on the basis of amino-acid composition analysis and by comparison of the N-terminal amino acids (seven out of 10 identities). 5. The exact relationship of this molecule to characterized heterodimers of higher vertebrates is unknown. 6. Cross-linked agarose-acetate was synthesized and proved to be an efficient concentrating agent and also a hydrophobic interaction adsorbant.

Amino Acid Sequence↗
PubMed1993

Spectral analysis and modelling of ACh and NE effects on shark nervus terminalis activity.

We investigated the effects of acetylcholine (ACh) and norepinephrine (NE) on activity in the nervus terminalis (NT) ganglion of the bonnethead shark (Sphyrna tiburo) using an in vitro preparation and whole nerve recordings. Spectral analysis indicated that ACh (10 and 100 microM) had a variable effect on the total spectral power of whole nerve activity but produced a consistent decrease in half power frequency (HPF; the median frequency of the power spectrum). Norepinephrine (10 microM) reduced baseline activity and total spectral power but produced an increase in HPF in all NT preparations. Computer simulations of extracellular recordings suggested a general explanation for these findings. Acetylcholine may have opposite effects on activity in two NT cell populations with axons in the central nerve trunk, increasing activity in cells whose axons have broad spikes (low spectral frequency) and decreasing activity in cells whose axons have narrow spikes (high spectral frequency). The NE effects are consistent with a decrease in activity of cells whose axons have broad spikes (low spectral frequency) and little or no change in cells whose axons have narrow spikes (high spectral frequency). The physiological data, together with the theoretical analysis, suggest that cholinergic and catecholaminergic neurotransmitter systems are active in the bonnethead NT ganglion, and that ACh and NE have different effects on two populations of ganglion cells.

Acetylcholine↗
PubMed1985

A comparative study of monooxygenase activity in elasmobranchs and mammals: activation of the model pro-carcinogen aflatoxin B1 by liver preparations of calf, nurse shark and clearnose skate.

Liver microsome preparations of the elasmobranchs Ginglymostoma cirratum (nurse shark) and Raja eglanteria (clearnose skate) were examined for monooxygenase activity using aflatoxin B1 as substrate. At equiprotein concentrations, elasmobranch microsomes were less than 20% as active as calf liver in producing mutagenic metabolites of aflatoxin B1.

Aflatoxin B1↗
PubMed1989

Measurement of monoamines and monoamine metabolites in various brain regions of six shark species.

1. The concentrations of six monoamines or monoamine metabolites were measured in six brain regions of six shark species using high performance liquid chromatography with electrochemical detection. 2. Serotonin concentrations were greatest in the hypothalamus and tegmentum, intermediate in the midline ridge formation, spinal cord and forebrain, and lowest in the cerebellum in all species. 3. Specie differences in dopamien concentration were significant only in the forebrain; species differences in the levels of the norepinephrine, epinephrine and 5-hydroxyindoleacetic acid were significant in most brain regions, including the midline ridge formation. 4. Differences and similarities to the mammalian pattern of monoamine distribution in the brain are discussed.

Animals↗
PubMed1993

A proteolipid protein gene family: expression in sharks and rays and possible evolution from an ancestral gene encoding a pore-forming polypeptide.

The myelin proteolipid proteins (PLP and DM20) are believed to act as "adhesive struts" in the extracellular apposition of the CNS myelin sheath. These proteins have been considered late evolutionary developments, which arose de novo in the antecedents of early tetrapods. However, PCR primed with degenerate oligonucleotides corresponding to common segments of rat PLP/DM20 revealed three novel mRNAs in the brains of two elasmobranchs. These mRNAs are closely related to each other and to mammalian DM20, but lack the sequence that distinguishes PLP from DM20. We term the novel proteolipid proteins DM alpha, DM beta, and DM gamma. At least DM alpha and DM gamma are highly expressed in white matter in myelinating shark brain. The DMs not only are highly homologous to each other, but also contain regions bearing similarities with segments of channel-forming regions of the nicotinic acetylcholine receptor and the glutamate receptor macromolecular complexes. Significantly, we find that across these segments, DM alpha and DM gamma are more similar to the channel proteins than the two channel proteins are to each other.

Amino Acid Sequence↗
PubMed2004

Characteristics of structure, composition, mass spectra, and iron release from the ferritin of shark liver (Sphyrna zygaena).

The ferritin consists of a protein shell constructed of 24 subunits and an iron core. The liver ferritin of Sphyrna zygaena (SZLF) purified by column chromatography is a protein composed of eight ferritins containing varying iron numbers ranging from 400+/-20 Fe3+/SZLF to 1890+/-20 Fe3+/SZLF within the protein shell. Nature SZLF (SZLFN) consisting of holoSZLF and SZLF with unsaturated iron (SZLFUI) to have been purified with polyacrylamide gel electrophoresis (PAGE) exhibited five ferritin bands with different pI values ranging from 4.0 to 7.0 in the gel slab of isoelectric focusing (IEF). HoloSZLF purified by PAGE (SZLFE) not only had 1890+/-20 Fe3+/SZLFE but also showed an identical size of iron core observed by transmission electron microscopy (TEM). Molecular weight of approximately 21 kDa for SZLFE subunit was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Four peaks of molecular ions at mass/charge (m/z) ratios of 10611.07, 21066.52, 41993.16, and 63555.64 that come from the SZLFE were determined by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS), which were identified as molecular ions of the ferritin subunit (M+) and its polymers, namely, [M]2+, [M]+, [2M]+, and [3M]+, respectively. Both SZLFE and a crude extract from shark liver of S. zygaena showed similar kinetic characteristics of complete iron release with biphasic behavior. In addition, a combined technique of visible spectrometry and column chromatography was used for studying ratio of phosphate to Fe3+ within the SZLFE core. Interestingly, this ratio maintained invariable even after the iron release, which differed from that of other mammal ferritins.

Animals↗
PubMed2004

Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient.

Bull sharks (Carcharhinus leucas) were captured across a salinity gradient from freshwater (FW) to seawater (SW). Across all salinities, C. leucas were hyperosmotic to the environment. Plasma osmolarity in FW-captured animals (642 +/- 7 mosM) was significantly reduced compared to SW-captured animals (1067 +/- 21 mosM). In FW animals, sodium, chloride and urea were 208 +/- 3, 203 +/- 3 and 192 +/- 2 mmol l(-1), respectively. Plasma sodium, chloride and urea in SW-captured C. leucas were 289 +/- 3, 296 +/- 6 and 370 +/- 10 mmol l(-1), respectively. The increase in plasma osmolarity between FW and SW was not linear. Between FW (3 mosM) and 24 per thousand SW (676 mosM), plasma osmolarity increased by 22% or 0.92% per 1 per thousand rise in salinity. Between 24 per thousand and 33 per thousand, plasma osmolarity increased by 33% or 4.7% per 1 per thousand rise in salinity, largely due to a sharp increase in plasma urea between 28 per thousand and 33 per thousand. C. leucas moving between FW and SW appear to be faced with three major osmoregulatory challenges, these occur between 0-10 per thousand, 11-20 per thousand and 21-33 per thousand. A comparison between C. leucas captured in FW and estuarine environments (20-28 per thousand ) in the Brisbane River revealed no difference in the mass of rectal glands between these animals. However, a comparison of rectal gland mass between FW animals captured in the Brisbane River and Rio San Juan/Lake Nicaragua showed that animals in the latter system had a significantly smaller rectal gland mass at a given length than animals in the Brisbane River. The physiological challenges and mechanisms required for C. leucas moving between FW and SW, as well as the ecological implications of these data are discussed.

Animals↗
PubMed2007

Polychlorinated biphenyls and DDT in swordfish (Xiphias gladius) and blue shark (Prionace glauca) from Brazilian coast.

The polychlorinated biphenyls (PCBs) and DDT may bioaccumulate in the aquatic food web and have been of great concern due to their toxic effects on wildlife and human health. There is evidence showing that fish in the human diet contributes at a significant proportion to the total intake of PCBs and other organochlorine compounds, particularly fish with higher fat levels. This study investigated the concentration of PCBs and DDTs in muscle tissues of samples of the blue shark (Prionace glauca) and a swordfish (Xiphias gladius) from east Brazilian coast and estimate the human exposure to total DDTs through the consumption of both the species. Samples of the each species were caught between August and September 2001. The mean concentration for summation operator PCBs in P. glauca was 3.15 ng/g w.w. and the summation operator DDTs was 0.93 ng/g w.w. The mean concentration of summation operator PCBs in X. gladius was 6.50 ng/g and the mean of summation operator DDTs was 2.47 ng/g. The estimated daily intake of summation operator DDT through X. gladius or P. glauca consumption can be considered safe since it contributes to less than 0.1% of the limit of acceptable daily intake (ADI) of summation operator DDT proposed by WHO.

Animals↗
PubMed2006

Nitric oxide production by nurse shark (Ginglymostoma cirratum) and clearnose skate (Raja eglanteria) peripheral blood leucocytes.

Reactive nitrogen intermediates, such as nitric oxide (NO), are important immunomodulators in vertebrate immune systems, but have yet to be identified as mediators of host defence in any member of class Chondrichthyes, the cartilaginous fishes. In the present study, production of NO by nurse shark (Ginglymostoma cirratum) peripheral blood leucocytes (PBL) stimulated with bacterial cell wall lipopolysaccharide (LPS) was investigated. PBL were cultured for 24 to 96 h following stimulation with LPS at concentrations ranging from 0 to 25 microg ml(-1), in both serum-supplemented and serum-free culture conditions. Production of NO was measured indirectly using the Griess reaction, with maximal NO production occurring after 72 h using 10% FBS and 10 microg LPS ml(-1). Application of these culture conditions to PBL from another cartilaginous fish (clearnose skate, Raja eglanteria) resulted in a similar NO response. Addition of a specific inhibitor of inducible nitric oxide synthase (iNOS), L-N(6)-(1-iminoethyl)lysine (L-NIL), resulted in a significant decrease in the production of NO by PBL from both species.

Analysis of Variance↗
PubMed2004

Structure and glycosylation of the term yolk sac placenta and uterine attachment site in the viviparous shark Mustelus canis.

The viviparous shark Mustelus canis nurtures its young within the uterus by means of a modified yolk sac which functions as a placenta. Two term specimens have been examined with a panel of 21 biotinylated lectins to assess whether glycans form a prominent interface between fetal and maternal tissues as in their therian counterparts. The yolk sac placenta was lined by a thin egg envelope which apposed though did not make contact with the uterine epithelium, and expressed fucosyl, N-acetyl glucosamine/lactosamine residues and some complex N-glycan, while the attached, thin ectoderm cells stained selectively with lectins from Anguilla anguilla and Arachis hypogaea indicating fucosyl and beta-galactosyl residues; other lectins bound to a variable degree. Large yolk sac endoderm cells were heavily glycosylated and expressed a wide range of glycans. The apposing uterine epithelium had two epithelial layers with distinctive patterns of glycosylation, the apical layer stained strongly with Anguilla anguilla lectin and the basal cells with lectins from Wisteria floribunda and Helix pomatia, the latter indicating plentiful N-acetyl galactosamine though both layers stained variably with other lectins also. A population of sparse, large, globular cells expressed alpha2,3-linked sialic acid and N-acetyl glucosamine oligomers. Fetal and maternal vessels were heavily glycosylated as in their therian counterparts. These data indicate a prominent role for glycans at the fetomaternal interface of these chondrichthyan fishes.

Animals↗