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PubMed2006

Use of isotopic analysis of vertebrae in reconstructing ontogenetic feeding ecology in white sharks.

We conducted stable 13C and 15N analysis on white shark vertebrae and demonstrated that incremental analysis of isotopes along the radius of a vertebral centrum produces a chronological record of dietary information, allowing for reconstruction of an individual's trophic history. Isotopic data showed significant enrichments in 15N with increasing sampling distance from the centrum center, indicating a correlation between body size and trophic level. Additionally, isotopic values verified two distinct ontogenetic trophic shifts in the white shark: one following parturition, marking a dietary switch from yolk to fish; and one at a total length of >341 cm, representing a known diet shift from fish to marine mammals. Retrospective trophic-level reconstruction using vertebral tissue will have broad applications in future studies on the ecology of threatened, endangered, or extinct species to determine life-long feeding patterns, which would be impossible through other methods.

Animals↗
PubMed1976

Excretion of phenol red and its glucuronide in the dogfish shark.

1. The biliary and urinary excretion of phenol red and its glucuronide was measured in dogfish sharks, Squalus acanthias, in both intact animals and animals with biliary fistula. 2. Phenol red is extensively metabolized to its glucuronide by the dogfish shark and both forms of the compound are actively transported into bile and urine. 3. Both compounds are transferred from plasma to urine and bile against a large concentration gradient; the transfer process is saturable most easily in the renal compartment but also in the hepatic compartment; and both excretion routes for the free drug and the glucuronide are inhibited by probenecid. 4. There were no significant differences in the 48 h biliary excretion of total (free + glucuronide) phenol red, but the urine or intact fish contained two-fold more total drug than did animals with fistulae.

Animals↗
PubMed1977

Fate and distribution of the herbicides 2,4-dichlor-phenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in the dogfish shark.

1. The urinary and biliary excretion, tissue distribution and metabolism of 14C-labelled 2,4-dichloro- or 2,4,5-trichloro-phenoxyacetic acids (2,4-D or 2,4,5-T) were measured in dogfish sharks, Squalus acanthias. 2. Both herbicides are extensively metabolized (greater than 90%) to the corresponding taurine conjugates, and are excreted predominantly via the urine, where ca. 70% of the administered dose appears within 4-6 days after treatment. 3. The highest tissue levels of 2,4-D or 2,4,5-T were found in liver and kidney. Penetration of both herbicides into the CNS was restricted. 4. Plasma elimination was rapid and the 0.5 for either phenoxyacetic acid was less than 45 min. Similarly, rapid clearance as seen from renal tissue. Final t0.5 values for muscle were about 2-3 days while the major organ showing 2,4-D or 2,4,5-T retention was the liver, where t0.5 values were about 5 days for both the herbicides. 5. The overall pharmacokinetics in the dogfish shark for these herbicides resembled those seen in some mammals.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1980

Renal handling of 2,4-D by the dogfish shark (Squalus acanthias).

1. The renal clearance of 2,4-dichlorophenoxyacetate (2,4-D) was studied in the dogfish shark, Squalus acanthias. 2. The clearance of total 2,4-D was more than 25 times greater than the glomerular filtration rate, which indicated that 2,4-D was secreted by the kidney. 3. The secretion of total 2,4-D was decreased by bromocresol green, an inhibitor of organic anion secretion, which also produced a concurrent decrease in the glomerular filtration rate. 4. As previously determined, 2,4-D was eliminated in the urine as the taurine conjugate (approximately equal to 95% of the excretion products). The plasma of the dogfish shark, however, contained primarily unconjugated 2,4-D (approximately equal to 90%) and only a minor amount of the taurine conjugate (approximately equal to 5%). The limited amount of the taurine conjugate in the plasma cannot account for its urinary excretion. Apparently 2,4-D is transported into the renal tubular cell, after which 2,4-D is conjugated with taurine before elimination into the urine.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1983

Skeletal lesions and deformities in large sharks.

Four blunt-snouted sandbar sharks (Carcharhinus plumbeus) were noted among 555 examined over a 13-yr period. Radiographs of one specimen revealed that the three rostral cartilage rods were abnormally short and failed to join at the anterior tip. The deformity appeared to be congenital. Four cases of vertebral lesions were noted in three species of shark (Carcharhinus plumbeus, Negaprion brevirostris and Odontaspis taurus). The vertebral columns had fused centra, ribs and neural arches, extra deposition and erosion of calcified material in the centra, and in one case, compression of centra. The causes of the vertebral lesions are unknown.

Animals↗
PubMed1999

Disseminated granulomas associated with nematode larvae in a shortfin mako shark.

A shortfin mako shark (Isurus oxyrinchus) caught in 1996 by sportfishermen in Long Island (New York, USA) had many granulomas containing larval nematodes. Granulomas were present in the myocardium, spleen, pancreas, stomach, spiral intestine, hematopoietic tissue within the anterior kidney, and in the branchial septum and primary lamellae of the gills. Epicardial hyperplasia and granulomatous myocarditis were associated with the larvae. Although identification of the larvae was impossible due to lack of distinct morphological features, they resembled dracunculoid larvae previously reported from sharks.

Animals↗
PubMed2000

Shark cartilage extract interferes with cell adhesion and induces reorganization of focal adhesions in cultured endothelial cells.

In this study, we examined the effects of shark cartilage extract on the attachment and spreading properties and the focal adhesion structure of cultured bovine pulmonary artery endothelial cells. Treatment with cartilage extract resulted in cell detachment from the substratum. Immunofluorescence staining of those treated cells that remained attached showed that, instead of being present in both central and peripheral focal adhesions as in control cells, both integrin alpha(v)beta(3) and vinculin were found only in peripheral focal adhesion and thinner actin filament bundles were seen. In addition to causing cell detachment, cartilage extract partially inhibited the initial adherence of the cells to the substratum in a dose-dependent manner. Integrin alpha(v)beta(3) and vinculin staining of these cells also showed a peripheral focal adhesion distribution pattern. Vitronectin induced cell spreading in the absence of serum, but was blocked by simultaneous incubation with cartilage extract, which was shown to inhibit both integrin alpha(v)beta(3) and vinculin recruitment to focal adhesion and the formation of stress fibers. Dot binding assays showed that these inhibitory effects on cell attachment and spreading were not due to direct binding of cartilage extract components to integrin alpha(v)beta(3) or vitronectin. Shark cartilage chondroitin sulfate had no inhibitory effect on either cell attachment or spreading of endothelial cells. These results show that the inhibitory effects of cartilage extract on cell attachment and spreading are mediated by modification of the organization of focal adhesion proteins.

Acid Phosphatase↗
PubMedDate not supplied

[Characteristics of the nitrous substances in the meat of sharks and rays as a protein food raw material].

The nitrous composition of meat in 19 species of oceanic sharks and 2 species of rays were analyzed. The meat of these fish species was found to be characterized by a comparatively low protein content, whose amino acids composition proved relatively poor of essential amino acids. The meat of sharks and rays is distinguished by a high level of extractives, whose bulk includes urea and trimethylaminoxide.

Amino Acids↗
PubMed2003

Inhibitory effect of Greenland shark liver oil combined with squalen and arctic birch ashes on angiogenesis and L-1 sarcoma growth in Balb/c mice.

Sharks have been claimed to be resistant to cancer and oil from their livers have been used in Scandinavian folk medicine as anti-tumor drug. Shark liver oil contains 40% or more of squalene. Fish liver oil is also rich in squalene and polyunsaturated n-3 fatty acids. The aim of this work was to determine the anti-angiogenic and anti-tumor effects of these substances, together with another Scandinavian traditional remedy--arctic birch ashes--in Balb/c mice after transplantation of syngeneic L-1 sarcoma. All substances tested, alone or in combinations, significantly diminished cutaneous angiogenesis induced by tumor cells, and tumor growth.

Animals↗
PubMed2005

[Determination of mercury in shark liver by cold atom fluorescence spectrometry after microwave dissolution].

The conditions for the determination of mercury in shark liver by cold atom fluorescence spectrometry (CAFS) with microwave dissolution were studied. After being dried completely, the method employed 2 mol x L(-1) HNO3-4 mol x L(-1) HCl as an oxidant, and with catalysis by V2O5, the samples were digested in a microwave oven. The mercury in absorption solution was reduced by SnCl2, and then was determined by CAFS at wavelength of 253.7 nm. 10% SnCl2 solution was used as a reductive agent for mercury. The linear range was 0-2.0 ng x mL(-1) mercury (r = 0.999 7). The detection limit was 0.05 ng x mL(-1), the relative standard deviation was 0.86%-2.22%, and the average recovery rate was 96.0%-108.5%. The method was suitable for the determination of mercury in shark liver.

Animals↗
PubMed2006

[Biological action and clinical application of shark liver oil].

Fish oils contain several active compounds that modify cell activity and influence various functions of the body. Shark liver oils are rich in alkylglycerols and squalene, but contain relatively low amounts of n-3 polyunsaturated fatty acids. Alkylglycerols may control immune response possibly throw modification of platelet activating factor (PAF) and diacylglycerol (DAG) production. Squalene enhances antigen presentation and induction of inflammatory response. Moreover, alkylglycerols and squalene have antitumour activity, that is possibly based on different mechanisms, ie., induction of apoptosis of neoplastic cells, suppression of signal transduction, inhibition of angiogenesis and promoting of transmembrane transport of cytotoxic agents. Shark liver oil has been found to be useful in treatment of conditions resulted from inadequate immune response, and in adjunctive treatment of several types of cancer.

Animals↗
PubMed1991

[A histo-anatomical study on the spleens of a frilled shark, Chlamydoselachus anguineus].

The spleens of a frilled shark, Chlamydoselachus anguineus was histo-anatomically studied. The results were as follows. 1. Two independent spleens, one in the dorsal mesogastrium and the other in the ventral mesenterium (Ligamentum hepatoduodenale), are noted. Splenic branches are provided either from a. lienogastrica for the former or from Truncus coelomesentericus for the latter. The venous system holds a non-collateral position to the arterial system and drains the intrasplenic blood by complicate routes. The vascular architecture of the intestinal tract of Chlamydoselachus is same as that of the sixgill shark, Hexanchus. 2. Histologically, both spleens consist of the white pulp (arteries and periarterial lymphatic sheath) and the red pulp. No active hemopoiesis is noted. Ellipsoids are present around arterial terminals. Arterial terminals communicate directly to venous vessels of the red pulp. Both incompletely-formed collateral veins of intrasplenic arteries and capsular drainage veins are noted. These features are essentially same as those of other elasmobranch spleens.

Animals↗
PubMed1991

[Shark liver oil (alkoxyglycerol) and cancer treatment].

Alkoxyglycerol derived from shark liver oil is marketed in Denmark and mentioned in popular articles as a supplementary agent in the treatment of cancer. A questionnaire investigation carried out in the Department of Oncology and Haematology in Odense Hospital revealed that approximately 1/3 of the patients in active neoplastic therapy employed shark liver oil preparations. The clinical investigations of alkoxyglycerol were all carried out on patients with cancer of the uterine cervix. All of the investigations were carried out by the same Swedish research group. Only a minority of the experimental material was blinded. No documentation was found for inhibited tumour growth or reduced mortality resulting from treatment with alkoxyglycerol. The number of cases of irradiation damage were found to be fewer in the groups treated with alkoxyglycerol, but the difference may be partially explained by different subdivision into stages. Alkoxyglycerol results in increase in the leukocyte and thrombocyte counts while higher or lower doses have, apparently, the opposite effect. The available literature concerning the clinical effect of alkoxyglycerol is limited and unsystematic and does not support the employment of alkocyglycerol in the treatment of cancer.

Animals↗
PubMed1989

Fatal Fusarium solani infections in baby sharks.

The occurrence of fatal fusariosis in baby bonnethead sharks (Sphyrna tiburo) born at the National Aquarium, Baltimore, Maryland, is reported. An atypical strain of Fusarium solani was cultured from the tissues of two of the infected sharks following postmortem examination. Histopathology revealed an apparent predilection of the fungus for hyaline cartilage. Invasion of the cartilage resulted in hyphae with a distorted morphology. In slide culture the fungus displayed the unusual characteristic of terminal chlamydoconidium generation on macroconidia; this may be of some taxonomic significance.

Animals↗
PubMed1989

Metabolic rate, heart rate, and tailbeat frequency during sustained swimming in the leopard shark Triakis semifasciata.

Heart rate, metabolic rate, and tailbeat frequency were simultaneously recorded from seven leopard sharks (Triakis semifasciata) during steady swimming at controlled speeds to evaluate the usefulness of heart rate as a measure of field metabolic rate. Heart rate was monitored by acoustic telemetry using a frequency modulated ECG transmitter. Metabolic rate was measured as oxygen consumption in a swimming tunnel respirometer. For instrumented sharks, mean resting oxygen consumption rate and heart rate were 105.3 +/- 35.6 (SE) mg O2.kg-1.h-1 and 36.6 +/- 1.8 (SE) beats.min-1, respectively. While swimming at the maximum sustained speed (0.84 +/- 0.03 lengths.s-1) for 30-60 min, these rates were 229.3 +/- 13.2 mg O2.kg-1.h-1 and 46.9 +/- 0.9 beats.min-1. Although a significant linear regression was obtained between metabolic rate and heart rate, a low overall correlation coefficient may result from the existence of separate individual regressions and confounding changes in stroke volume and/or arteriovenous oxygen difference. Heart rate was approximately as closely correlated with oxygen consumption rate as swimming speed was. A significant linear relationship was obtained between tailbeat frequency and swimming speed to speeds of 0.75 lengths.s-1.

Animals↗
PubMed1979

Local analysis or the composition of amphibian and shark teeth using laser probe mass spectrometry.

In the intention of confirming and extending previous studies on the ultrastructure of the teeth of the lower vertebrates, we have performed analyses of the amounts of various chemical elements present in the teeth of two amphibians and a shark. For this purpose we employed a laser probe mass spectrometer, with which we were able to measure profiles of the variation of amount of the different elements with depth at the different points chosen for analysis. The results are expressed as relative abundances using phosphorus as reference. Differences in the relative amounts of many elements can be observed at different sample points on a tooth, and, for a given sample point, at different depths. These differences certainly reflect ultrastructural features, although some of these may not yet have been described. Fluorine has been found to be much abundant in the teeth of a shark than in those of amphibians.

Amphibians↗
PubMed1985

Permeability of external gill filaments in the embryonic shark. Electron microscopic observations using horseradish peroxidase as a macromolecular tracer.

External gill filaments of sharks are purely transient embryonic structures. They contain a single vascular sinusoidal loop that is continuous with the afferent and efferent branchial arteries. Each filament is comprised of a squamous epithelial bilayer that rests upon a prominent basal lamina. A collagenous stroma separates the epithelium from the underlying endothelium. The epithelium, from an embryo 4.5 cm in total length, is characterized by microvilli with smooth walled vesicles at their bases, a luminal glycocalyx, prominent tubular and vesicular elements, rough endoplasmic reticulum, a Golgi complex, a flattened nucleus, coated vesicles, lipid-like inclusion bodies and sparse cytoplasmic fibrils. Adjacent epithelial cells are joined by a zonula occludens, a zonula adherens and up to five maculae adherentes. The endothelium possesses mitochondria, rough endoplasmic reticulum, a Golgi complex, coated vesicles and many micropinocytotic vesicles on both the adluminal and abluminal surfaces. The endothelium has no basal lamina and is not associated with smooth muscle. After exposure to horseradish peroxidase (HRP) for 10 min, reaction product nearly occludes the cytoplasm of some surface epithelial cells. The deeper epithelial cells have reaction product in smooth walled vesicular and tubular elements. Reaction product is also present in smooth walled endothelial vesicles. Gill filaments from a 10 cm embryo show marked changes from earlier stages. In the epithelial cells, there is an increase in the number of cytoplasmic filaments and the formation of a dense terminal web. Fewer vesicles, tubules, rough endoplasmic reticulum and mitochondria, and a less elaborate Golgi complex characterize the epithelium. The endothelium remains unchanged. The amount of collagen increases and fibroblasts are observed in the stroma. These modifications contribute to the strength of the filaments and allow the gills to withstand increased abrasion by the developing skin denticles. These experiments establish the capability of external gill filaments to take up a macromolecular tracer in the form of horseradish peroxidase. Later in development, the yolk sac of R. terraenovae becomes modified as a yolk sac placenta which functions both in respiration and hematrophic nutrition. In viviparous sharks, the uterus elaborates nutrient-rich secretions. External gill filaments may thus serve as a nutrient absorptive membrane before the establishment of the yolk sac placenta as well as perform its respiratory function.

Animals↗