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PubMed1977

Statistical comparison of the results from six analytical chemistry laboratories of the mercury content of muscle tissue of two species of sharks.

Statistical tests were carried out on the results of chemical analysis for total mercury concentrations of replicate samples of muscle tissue of school shark Galeorhinus australis (Macleay) and gummy shark Mustelus antarcticus Guenther from six independent analytical laboratories. These tests showed that one laboratory produced results 9% below the overall average of all results, another 1% below average while the other four were all 5% above average. Moreover, one laboratory had significantly lower scatter of results than the others, and the percentage scatter (standard error expressed as a percentage of the mean) in two of the laboratories tended to diminish as the magnitude of the results increased. Correction for what were concluded to be wild points indicated that the scatter for all laboratories was below 14%.

Analysis of Variance↗
PubMed1979

Shark heart mitochondria: effects of external osmolality on respiration.

Shark mitochondrial respiration was studied in media with osmolalities between 160 and 1500 milliosmoles. The respiratory control ratio, a marker for functional integrity of the isolated mitochondria, was maximal at 1000 millismoles and decreased during hypotonic or hypertonic exposure. Shark mitochondria function best at their native tonicity, a value that produces abnormal function in mammalian mitochondria.

Adenosine Diphosphate↗
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↗
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↗
PubMed1979

Quantitative anatomical and behavioral analyses of regeneration and collateral sprouting following spinal cord transection in the nurse shark (ginglymostoma cirratum).

The spinal cord was transected at the mid-thoracic level in 32 nurse sharks. Four animals per group were sacrificed at intervals of 10, 20, 30, 40, 60 and 90 days postoperative. Two groups of fish underwent a subsequent spinla1 cord retransection at the same site at 90 days and were sacrificed 10 and 20 days later. Three sections of spinal cord were removed from each shark for histological analysis. Behaviorally, timed trials for swimming speed and a strength test for axial musculature contraction caudal to the lesion site were performed at 5 day postoperative intervals. Histological analysis showed little regeneration (9-13 percent) of two descending tracts 90 days following the lesion and no return of rostrally controlled movements caudal to the lesion. However, synaptic readjustment did occur caudal to the lesion. This phenomenon was attributed to local segmental sprouting of adjacent, intact nerve fibers. A close correlation was shown between this synaptic readjustment and the strength of uncontrollable undulatory movements seen caudal to the lesion site following spinal cord transection. The relationship of regeneration and collateral sprouting to quantitative behavioral changes is discussed.

Animals↗
PubMed1979

[A macroscopical study of the nervus glossopharyngeus of shark (Mustelus manazo) (author's transl)].

Branches of the Nervus glossopharyngeus of shark Mustelus manazo, one of the most typically retained branchial nerves, is studied macroscopically with a hope of comprehension of its original morphological meanings. There were found some anastomosis among the terminal branches of the Ramus pharyngeus dorsalis of this nerve and those of the Nervus facialis, which, though in the fine caliber of branches, probably could be considered as prototype of the JACOBSON's anastomosis encountered in other vertebrates. In addition to the hitherto reported different content of their nerve components Ramus pretrematicus and posttrematicus of the N. glossopharyngeus of the shark take essentially different courses from each other, especially in relation to the Arteria efferentis branchialis:the former courses always medial to this artery, while the latter is situated laterally to this artery in the branchial arch. The Ramus pretrematicus, in this regard, seemed rather to be equivalent to the Ramus comitans internus a. branchialis of the intermediate branches of the N. glossopharyngeus. Filamentous branches were observed to be emitted from the Ramus externus comitans a. branchialis and distributed to the gill lamellae.

Animals↗
PubMedDate not supplied

[A comparative characteristic of DNA pyrimidine sequences of shark, protopterus and perch].

Pyrimidine sequences of DNA from three fishes: shark, protopterus and perch have been studied. These data together with the evidence from the literature were used to support earlier conclusions that dipnoi and cartilagenous fishes should be distinguished as independent classes. The clustering index, beta, and the total molar percentage of long pyrimidine oligonucleotides (Z) containing greater than or equal to 8 nucleotides--a new parameter offered by us--have been used in comparative investigation of DNAs. The new parameter has permitted to obtain a higher resolution in the analysis of our own and literature data on DNA pyrimidine clusters in fishes. Investigation of pyrimidine clusters and of the base composition of individual isoplits of these clusters using statistical analysis showed that DNA from shark, protopterus, sturgeon and perch significantly differ by many features. Significant differences between these DNAs were found also in the base composition. Thus, new evidence for distinguishing cartilagenous fishes and dipnoi as independent classes have been received.

Animals↗
PubMed1975

Cytoarchitecture of the optic tectum in the nurse shark.

The cytoarchitecture of the optic tectum of the nurse shark is described and related to the arrangements of afferents from retina, telencephalon and contralateral tectum. Its lamination is not pronounced when compared to tecta of most other non-mammalian species but more comparable to those of mammals. The absence of highly differentiated cells such as pyramidal and true horizontal cells is perhaps correlated with the poor differentiation in general, including the apparent partial overlap of inputs. Some neurons near the midline were found to possess dendrites extending into the contralateral tectum.

Animals↗
PubMed1976

The structure of the hypothalamic inferior lobes of the blacktip reef shark: scanning and transmission electron microscopic observations.

The inferior lobes of the shark hypothalamus were examined with light, transmission and scanning electron microscopy. The cells bordering the floor of the lateral recess appear to be typical liquor-contacting neurons. With scanning electron microscopy (SEM) the apical ends of these cells are seen to bulge into the ventricular lumen. In contrast, the roof is lined by a more typical ependymal cell characterized by numerous cilia and microvilli. In addition, SEM reveals several kinds of supraependymal cells with processes that appear to penetrate the ventricular lining. A periventricular nucleus underlies the ependymal cells. Neurons of the periventricular nucleus contain numerous lipofuchsin granules. The rest of the inferior lobe consists of many neuronal fibers. The morphology of the hypothalamic inferior lobe is discussed in relation to its possible role in feeding and aggressive behavior in both elasmobranchs and teleosts.

Animals↗
PubMed1977

Ultrastructure of the different fibre types in axial muscles of the sharks Etmopterus spinax and Galeus melastomus.

Red, intermediate and white axial muscle fibres of the sharks Etmopterus spinax and Galeus melastomus were studied by electron microscopy and morphometry. The mitochondrial content is more than thirty percent in red, less than one percent in white, and up to fifteen percent in intermediate fibres. About one third of the mitochondria in red fibres are accumulated close to the sarcolemma. Red fibres contain much glycogen, present as rosettes (alpha particles). Intermediate fibres contain less glycogen (as beta particles). White fibres have scarcely any visible energy reserves. Red fibres contain slightly less (4-5%) of the sarcotubular system than the other fibre types (6-8%). In all fibre types, the terminal cisternae of the SR are regularly divided by clefts. Triads or dyads are generally positioned at the Z discs, but in Galeus white fibres two dyads may be present, one on each side of the Z disc. The morphology is discussed in relation to current views on the functions of different muscle fibre types.

Animals↗
PubMed1977

Morphometric and autoradiographic studies on the growth of red and white axial muscle fibres in the shark Etmopterus spinax.

The axial muscle growth of the shark Etmopterus spinax has been studied by means of morphometry, slide histology and autoradiography from radioactive thymidine and amino acids. Comparisons have been made between the red and white muscles fibres. While growing from 10 to 23 cm in length, the white muscle transverse sectional (ts) area increases 5.4 times, while the red area increases 3.7 times. The mean ts area of individual white fibres increases by 2.7, and the ts area of red fibres increases by 1.6. The number of white fibres does not increase significantly, while the red fibres increase slightly in number. Red fibres incorporate amino acids faster than the white fibres, and have a higher turnover rate. The myonuclei of the red fibres (satellite cell nuclei) incorporate thymidine more often than do those of white fibres, but the frequency of the satellite cells is similar in the two fibre types. Mitoses are extremely rare in the myonuclei. The nucleocytoplasmic ratio is higher in the red than in the white fibres.

Amino Acids↗
PubMed1976

Response to angiotensins I and II and to AI-converting-enzyme inhibitor in a shark.

The spiny dogfish shark, which does not have renal juxtaglomerular cells, exhibits a strong pressor response to both angiotensin I and II. A nonapeptide, angiotensin I-converting-enzyme inhibitor, blocks the pressor response to angiotensin I in this fish. The pressor response to both angiotensin II and norepinephrine is completely blocked by the adrenergic blocking drug phentolamine.

Adrenergic alpha-Antagonists↗
PubMed1979

Serially etched shark enameloid observed by incident light microscopy.

Longitudinal and transverse tooth sections of Isurus oxyrinchus were serially etched in 2.6% nitric acid. The changing optical properties of the etched surfaces were observed during the serial etchings, and the descent of the enameloid surfaces was measured. Shark enameloid seems to be less effectively etched by acid than human enamel; this difference may be due to differences in solubility between fluorapatite and hydroxyapatite. Most of the information regarding the structure of the enameloid was gained during the first five of ten etchings. The reflection of light from the surface was influenced by the orientation of the crystallites, longitudinally sectioned crystallites reflecting the light better than transversely sectioned crystallites. The dentinal extensions were continuous with and of the same structure as the underlying dentine. The radial fibers originated from the dentinal extensions, and they both contained organic material and were accompanied by crystallites. When the specimens were imbibed with water the distinctness of the dentinal extensions and radial fibers was improved.

Acid Etching, Dental↗
PubMed1976

An experimental model for the study of endolymphatic hydrops in sharks: implications for the clinician.

In recent years, attention has focused on the role of the endolymphatic sac (ELS) and the endolymphatic duct (ELD) in the pathogenesis of endolymphatic hydrops (ELH). Changes have been noted surgically and radiographically by others in the ELS and ELD in patients with ELH. This report summarizes the development of a shark model with which to study the pathophysiology of ELH. The background material and overall results of anatomic, histopathologic, and ultrastructural studies using the model are presented. Possible implications for the clinical handling of ELH as a result of this work is emphasized.

Animals↗
PubMed1975

Isolation and identification of prostaglandin E2 from gastrointestinal tract of shark Triakis scyllia.

A prostaglandin was isolated from the gastrointestinal tract of the shark Triakis scyllia and identified as prostaglandin E2 by bioassay, thin-layer chromatography, gas-liquid chromatography, ultraviolet absorption spectrometry and mass spectrometry. The fatty acid composition of the tissue was also determined. The amount of eicosatetraenoic acid in this tissue was 17.2% of the total fatty acids, but the percentages of eicosatrienoic acid and eicospentaenoid acid were low.

Animals↗
PubMed1976

Studies on fish liver protein synthesis. II. Factors influencing the aminoacylation of shark liver transfer ribonucleic acid.

The influence of buffer, pH, Mg2+, ATP, Na+, K+ and temperature on the extent and rate of aminoacyl-tRNA synthesis was studied with the shark Mustelus mento liver tRNAs and aminoacyl-tRNA synthetases. The optimum pH for the aminoacylation of tRNAMet was 8.3 and for tRNAVal 7.0. For these two tRNAs the Mg2+ optimum was related to the levels of ATP required and to the pH of the reactions. It is suggested that the Mg2+ concentration required for each aminoacylation system reflects the true conditions under which the substrate for the enzyme, the MgATP2- complex, is formed. The effect of monovalent cations was also examined. Val-tRNA synthesis was slightly stimulated up to a concentration of 50 mM NaCl (KCl). Over 100 mM salt, a rapid inhibition was observed. Met-tRNA synthesis behaves differently by being stimulated over a wide range of salt concentrations.

Acetylation↗
PubMed1977

First aid for shark attack victims.

A first-aid kit designed for the treatment of shark attack victims is presented. Emphasis is placed on the control of massive haemorrhage, the restoration of plasma volume and the transfer of the patient to hospital after initial shoch has been treated on the beach.

Animals↗
PubMed1978

[Embryonal development of the brain of the shark Scyliorhinus canicula (L.). I. Formation of the shape of the brain, the migration mode and phase and the structure of the diencephalon].

Brain structure of the shark Scyliorhinus canicula has been studied on the basis of a series of embryonic stages. The incubation time was 157 days in average (under constant conditions of 15 centigrades and density of 1.026). 1. The first predominant characters of the external brain shape are the optic tectum, cerebellum, telencephali hemispheres and oculomotor root. In addition, the brain axis is characterized by new flexures in the cerebellar and prosencephalic level. A nuchal flexure in absent. 2. The ontogenetic pattern of the matrix layer differs in different brain parts. Generally, ventral columns develop earlier than dorsal ones. Matrix development and cell proliferation occur especially late in the cerebellum. For the most part the results agree with findings by KAHLE (1951) concerning the human brain. The telencephalon is an exception and shows a developmental retardation, while a regular development is observed in Scyliorhinus. 3. The hypothalamus overlaps the other regions of the diencephalon. The ventral thalamus is small, a dorsal thalamus is not observed. The pretectal region is remarkably differentiated and contains a rich set of nuclei. 4. The epithalamus is asymmetrical; a phenomenon that occurs after hatch. The left habenula is distinctly larger than the right-one.

Animals↗