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At least 19 recordsLinked to original sources
PubMed1990

Sequence analysis of homogeneous peptides of shark immunoglobulin light chains by tandem mass spectrometry: correlation with gene sequence and homologies among variable and constant region peptides of sharks and mammals.

Morphologically, sharks are living fossils that are remarkably similar to their Devonian ancestors of ca. 400 million years ago. If a parallel conservation in biochemical properties characterizes shark evolution, knowledge of the properties of shark immunoglobulins should provide information on the structure of primordial immunoglobulins and their genes. The problem of polyclonality of shark immunoglobulins has precluded detailed analysis of shark immunoglobulin light polypeptide chains. Here, we approach the problem of obtaining direct sequence information on polyclonal light chains of shark immunoglobulins by isolating homogeneous peptides from tryptic digests of shark light chains and sequencing these by tandem mass spectrometry. To confirm the location of the peptides, we isolated a complementary DNA (cDNA) clone from a sandbar shark cDNA library in the expression vector lambda gt11, identifying the clone by its ability to produce a peptide serologically detectable using rabbit antibody to purified shark light chain. The correspondence between peptide sequence and that derived from gene sequence provided direct proof that the gene studied was that of a major expressed serum light chain. Using this combined approach, we isolated homogeneous peptides from both constant and variable regions. The variable region peptides showed homology to corresponding sequences of mammalian V lambda and V kappa sequences. The constant region gene sequence we obtained was homologous to mammalian C lambda sequence. The four constant region tryptic peptides we sequenced corresponded exactly to stretches of the C lambda sequence derived from the DNA sequence. The combined approach described here shows that shark light chains exhibit heterogeneity at both the protein and gene level, but that the constant regions of these chains can be identified as homologs of mammalian lambda chains and that evolutionary conservation has occurred in V region sequences ranging from elasmobranchs to man.

Amino Acid Sequence↗
PubMed1991

Allometric relationships of the dentition of the great White Shark, Carcharodon carcharias, in forensic investigations of shark attacks.

As a result of a systematic morphometric study of shark dentitions, a system of notation for describing the location of shark teeth has been developed and is proposed as a standard to be adopted for use in similar studies in the future. The macroscopic morphology of White Shark teeth has been characterised in order to gain quantitative data which might assist in identification of these sharks from bite marks on victims or objects or from shark carcasses. Using these data, a nomogram has been developed which can be used to estimate the body length of a White Shark from measurements of tooth or bite mark morphology. An example of the forensic application of such allometric data is provided as it applied to a recent fatal attack on a diver by a White Shark.

Animals↗
PubMed1988

Temperature-dependencies of various catalytic activities of membrane-bound Na+/K+-ATPase from ox brain, ox kidney and shark rectal gland and of C12E8-solubilized shark Na+/K+-ATPase.

The temperature dependence of ouabain-sensitive ATPase and phosphatase activities of membrane fragments containing the Na+/K+-ATPase were investigated in tissue from ox kidney, ox brain and from shark rectal glands. The shark enzyme was also tested in solubilized form. Arrhenius plots of the Na+/K+-ATPase activity seem to be linear up to about 20 degrees C, and non-linear above this temperature. The Arrhenius plots of mammalian enzyme (ox brain and kidney) were steeper, especially at temperatures below 20-30 degrees C, than that of shark enzyme. The Na+-ATPase activity showed a weaker temperature-dependence than the Na+/K+-ATPase activity. The phosphatase reactions measured, K+-stimulated, Na+/K+-stimulated and Na+/K+/ATP-stimulated, also showed a weaker temperature-dependence than the overall Na+/K+-ATPase activity. Among the phosphatase reactions, the largest change in slope of the Arrhenius plot was observed with the Na+/K+/ATP)-stimulated phosphatase reaction. The Arrhenius plots of the partial reactions were all non-linear. Solubilization of shark enzyme in C12E8 did not change the curvature of Arrhenius plots of the Na+/K+-ATPase activity or the K+-phosphatase activity. Since solubilization involves a disruption of the membrane and an 80% delipidation, the observed curvature of the Arrhenius plot can not be attributed to a property of the membrane as such.

Animals↗
PubMed1990

Comparison of the gamma-crystallins isolated from eye lenses of shark and carp. Unique secondary and tertiary structure of shark gamma-crystallin.

gamma-Crystallin isolated from the shark of cartilaginous fishes was compared with the cognate gamma-crystallin from the carp of bony fishes. Distinct differences in amino acid compositions, primary, secondary and tertiary structures were found. The most salient features of shark gamma-crystallin lie in the fact that this crystallin possessed a significant alpha-helical structure in the peptide backbone as revealed by circular dichroism study, in contrast to those orthologous gamma-crystallins from other vertebrate species including bony fishes which all show a predominant beta-sheet secondary structure. The tertiary structure as reflected in the intrinsic microenvironments of various aromatic amino acids in the native crystallins also shows unambiguous differences between these two classes of gamma-crystallins. N-Terminal sequence analysis corroborates the structural differences between shark and carp gamma-crystallins. gamma-Crystallin from the more primitive shark seems to be more in line with the main evolutionary phylogeny leading to the modern mammalian gamma-crystallin.

Amino Acid Sequence↗
PubMedDate not supplied

Identification of a second immunoglobulin in the most primitive shark, the frill shark, Chlamydoselachus anguineus.

Three molecular forms of immunoglobulins: pentamer, dimer and monomer, were isolated from serum of the frill shark, Chlamydoselachus anguineus, the most primitive extant shark. A pentamer having an apparent mass of 900 kDa, consisting of 68 kDa heavy (H) chains and 22-24 kDa light (L) chains, was considered to be IgM because of its similarity to mammalian IgM in both molecular form and H chain molecular weight. The dimer and monomer with apparent masses of 300 kDa and 150 kDa, respectively, were composed of the same H chains of 45-50 kDa, a value smaller than that of the H chains from the pentamer, and light chains identical to those of the pentamer. The H chains of 68 kDa and 45-50 kDa represented individual epitopes and were synthesized by different plasma cells. We thus concluded that the frill shark has two distinct classes of immunoglobulins: one a pentameric IgM and the other a second class of immunoglobulin with dimeric and monomeric structure. The presence of the second Ig is of considerable interest with respect to antigen recognition and exclusion.

Animals↗
PubMed1990

Shark tooth morphogenesis. An SEM and EDX analysis of enameloid and dentin development in various shark species.

The study provides a survey of shark tooth morphogenesis based on SEM and EDX analyses of whole tooth families in six shark species. The teeth, demonstrating different stages of development, were acid-etched and coated with palladium. Calcium content was determined semi-quantitatively by using the palladium coating as an internal standard. Due to the rapid development of the enameloid, all major events took place in the two or three youngest teeth of a tooth family. Enameloid appeared to develop as a transformation of the peripheral part of the dental papilla. Mineralization started immediately. Based on morphological criteria the middle zone of the enameloid was established at an early stage, excluding the possibility of an unambiguous centrifugal or centripetal direction of growth. Substantial mineral increase first occurred in the middle zone, spreading from the tooth tip toward the base. Dentin formed after the enameloid was completely established. Dentin formation started basally as a direct prolongation of the enameloid cap, then spreading toward the tooth tip, first along the edges. It is concluded that shark enameloid has a mesenchymal background, but a role played by the inner dental epithelium can not be excluded.

Amelogenesis↗
PubMed1989

Branchial blood flow distribution in the blue shark (Prionace glauca) and the leopard shark (Triakis semifasciata).

Electromagnetic flow (EMF) quantification of total cardiac stroke flow is not feasible for most elasmobranchs because the vascular anatomy precludes probe placement adjacent to the heart and proximal to all afferent branchial arteries (aba). Most previous studies report a fractional cardiac flow, made with the EMF probe placed on the ventral aorta between the innominate arteries and aba 3. Estimation of total cardiac stroke flow from such data requires a flow correction factor obtained by sacrificing the fish, and carrying out a two step in situ/in vitro flow calibration procedure which is based on tenuous assumptions. Ventral aortic blood flow measurements using the EMF techniques were carried out on large blue sharks, and radiographic imaging studies of ventral aortic and branchial blood flow were done on leopard sharks to verify previously estimated fractional cardiac stroke flow correction factors. The innominate flow fraction determined for both species in these studies are similar and agree with previous estimates for elasmobranchs. EMF data for Prionace show 38% of cardiac stroke flow goes to the innominate arteries, 23% into aba 3, 12% into aba 4, and 27% into aba 5. Radiographic analyses with Triakis reveal that 32% of its cardiac stroke volume flows into the innominate arteries which is in agreement with the in situ/in vitro fractional flow estimate (33%).

Animals↗
PubMed1988

Partial characterization of immunoglobulin light chains of carcharhine sharks: evidence for phylogenetic conservation of variable region and divergence of constant region structure.

Isolated light chains of IgM-type immunoglobulins of carcharhine sharks were analyzed by serological and biochemical means. When analyzed by isoelectric focusing analysis, light chains of the tiger shark (Galecerdo cuvieri), the galapagos shark (Carcharhinus galapagensis) and the sandbar shark (Carcharhinus plumbeus) showed a broad, but patterned, spectrum of bands ranging from pI 5.0 to 7.7 in which discrete families were observed. Serologically, light chains of the galapagos shark cross-reacted with rabbit antibodies against mouse immunoglobulin and a synthetic peptide corresponding to the J segment of T cell receptor beta chain. The latter cross-reaction is shared among light chains and T cell receptors. Although there was considerable heterogeneity in isoelectric focusing analysis, the light chains were homogeneous on the basis of apparent mass (23 kDa) and those of tiger shark and galapagos shark had relatively homogeneous dominant N-terminal sequences representing the first framework. The N-terminal sequences of these two shark light chains, were strongly homologous to one another and showed 75% identity to certain V kappa sequences of man and dog. Homology was also shown to V lambda sequences, but the degree of identity was approximately 50%. Following cleavage of the tiger shark light chain with o-iodosobenzoic acid which cleaves at tryptophanyl residues, a constant region peptide was isolated by gel filtration. It was possible to identify the homolog of this peptide within the constant regions of mammalian kappa and lambda chain, but the relationship to C kappa chain was stronger. The degree of identity among the corresponding C region peptides of mammalian, avian and elasmobranch species was much less than that observed for the framework 1 sequence of the light chain variable region. These data support the concept that variable and J region sequence have been conserved in the evolution of placoderm-derived vertebrates, but that constant regions show much greater phylogenetic variation.

Amino Acid Sequence↗
PubMed1985

[Formulation and evaluation of the protein quality of a flour mixture of shark fillet by-products and shrimp heads].

A flour proposed as a protein source for chick feeding was evaluated. The flour consisted in a 1.00:1.15 dry mixture of by-products from shark filleting (dt) and shrimp by products (cc). It had a crude protein content of 55.66%, a Ca:P ratio of 5.76 and an essential amino acid pattern similar to that of fish meal and/or shark meat. Methionine proved to be the first limiting essential amino acid. The shark meat and the by-products from shark filleting had adequate levels of available lysine (from 337 to 383 mg/g N). The flour had a fineness modulus (F.M.) of 3.95, an average particle diameter of 0.0175 inches (0.444 mm) and a uniformity index of 1:5:4 (coarse:medium:fine parts). The flour was considered suitable for chick feeding. The protein quality of the flour mixture (dt-cc) was evaluated in rats using diets which contained 3, 6, 9 and 12% protein from the product, and determining the PER, NPR and NGI values. Diets containing similar protein levels prepared from dried shark meat flour, mixed with casein, were used as standards. The flour mixture (dt-cc) had a PER of 1.60, an NGIo of 2.46, an NGI of 2.49 and an apparent digestibility of 88.80%. These values proved to be significantly (p less than 0.05) lower than those found for the corresponding shark meat flour-casein standard diets. The above results are partially explained by the high mineral content, high Ca:P ratio and high Na and K of the dt-cc mixture, factors which could interfere with the utilization of the most limiting essential amino acids and other nutrients, as some vitamins, in these diets. The Kruskal-Wallis test of the feed efficiency (EA) data obtained in growing chicks revealed that there was a significant (p less than 0.05) difference between the EA values obtained with the dried shark meat-containing diets and the standard commercial diets (Purina and a diet based on a 1.6:1.0 soybean meal:cottonseed meal mixture). No significant differences were found between the dt-cc mixture-containing diets and the commercial ones used as standard. The diet containing 6% shark meat flour was found to be the best based on the EA data. The diet with 12% of the dt-cc mixture gave similar EA values than all those containing shark meat flour; however, the greater nutritional-economic impact based on the EA data was found for the diets containing 3 and 6% of the dt-cc flour mixture.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids, Essential↗
PubMed1988

Fc receptor for shark IgM.

Fc receptors for shark IgM have been demonstrated on shark leukocytes. Measurement of receptor binding required treatment of leukocytes with Cytochalasin D to inhibit phagocytosis. EA rosetting assays were carried out using human erythrocytes coated with shark anti-human antibody. Binding to shark leukocytes was demonstrated to be specific to shark IgM in that affinity purified shark IgM and purified Fc5 mu fragments could block rosette formation, but not shark transferrin, bovine serum albumin or fetal bovine serum. The binding was shown to be saturable and reversible, characteristic of receptor-ligand interaction. Further, it was shown that affinity purified, radioiodinated IgM could also bind Cytochalasin D-treated shark leukocytes in a manner analogous to rosetting. We conclude that Fc receptors appeared early in evolution, and that previous difficulties in demonstrating the Fc mu receptor resulted from non-specific binding associated with phagocytosis.

Animals↗
PubMed1992

Molecular phylogeny of the prickly shark, Echinorhinus cookei, based on a nuclear (18S rRNA) and a mitochondrial (cytochrome b) gene.

The classification of the sharks is unclear. This is particularly true for the superorder Squalomorphii. The relationships between the squalomorphs and other superorders of sharks and the relationships between the different orders within the squalomorphs are a matter of debate. Here, we report a molecular phylogeny for a little known member of this superorder, the genus Echinorhinus. Echinorhinus is most commonly classified in either the family Echinorhinidae (Squaliformes) or the family Squalidae (Squaliformes). However, some authors have suggested a closer relationship to the order Hexanchiformes. In an attempt to shed light on this controversy, we have cloned, sequenced, and compared two genes widely used in molecular phylogeny studies, the cytochrome b and the 18S rRNA from the rare prickly shark, Echinorhinus cookei, and two potential relatives, the spiny dogfish Squalus acanthias (Squaliformes), and the sevengill shark, Notorynchus cepedianus (Hexanchiformes). The sequences of these genes for the prickly shark, the dogfish, and the sevengill shark were found to be equally divergent, suggesting that the prickly shark is no closer to the order Squaliformes than to the order Hexanchiformes.

Animals↗
PubMed1977

Haemoglobins of the shark, Heterodontus portusjacksoni. III. Amino acid sequence of the beta-chain.

The amino acid sequence of the beta-chain of the principal haemoglobin from the shark H. portusjacksoni has been determined. The chain has 141 residues, the same as that of mammalian alpha-chains and less than the 146 residues of mammalian beta-chains or the 148 residues of the alpha-chain from the tetrameric shark haemoglobin. The sequence was deduced from the sequences of peptides obtained by digestion of the globin or its cyanogen bromide fragments with trypsin, chymotrypsin, pepsin and papain. The difference in length of the beta-chain is most readily accounted for by the absence of the D helix. This small helical section is normally present in myoglobins and beta-globins but absent in alpha-chains. The deduction that it is absent from shark beta-chain is based on consideration of homology. The beta-chain shows the insertion of histidine beta2 and the deletions corresponding to residues A17 and AB1 relative to alpha-and myoglobin chains. The reactive thiol group in shark haemoglobin was shown by radioactive labelling to be residue 51 in the beta-chain, immediately preceding the E helix. The amino acid sequence of shark beta-chain shows 92 differences from human beta-chain, significantly more differences than shown by chicken or frog beta-chains, in line with its earlier time of divergence. If the tertiary structure of the shark beta-chain is the same as that of the horse then there are two changes in the alpha1beta2 contact site in oxyhaemoglobin and an additional one in deoxyhaemoglobin. When both alpha- and beta-chain contacts are considered there is a total of nine changes in residues involved in the alpha1beta2 contacts. There is no Bohr effect in shark haemoglobin, and of the residues normally involved in this effect the C-terminal histidine residue of the beta-chain is present, but the aspartyl (FG1) residue to which it is salt-linked is not, being replaced by a glutamyl residue.

Amino Acid Sequence↗
PubMed1992

Complete sequence of a cDNA clone specifying sandbar shark immunoglobulin light chain: gene organization and implications for the evolution of light chains.

A full-length cDNA clone specifying sandbar shark (Carcharhinus plumbeus) immunoglobulin light chain has been isolated and sequenced. By alignment with human lambda chains, the leader, framework, complementarity-determining, joining, and constant regions are clearly identified in the shark light chain. Approximately 40-50% identity is shared between the human and shark sequences in the variable and constant regions. We have performed sequence comparisons of the individual segments and constructed phylogenetic trees for the variable region. These studies identify the shark protein as a lambda chain. In addition, the sandbar shark light chain is only distantly related to that of horned shark (Heterodontus francisci) [Shamblott, M. J. & Litman, G. W. (1989) Proc. Natl. Acad. Sci. USA 86, 4684-4688], demonstrating that the long evolutionary time of divergence among shark species has led to the generation of substantial differences in sequence. The positions of the variable, joining, and constant gene segments in 14 genomic clones have been mapped. The segments are linked in individual clusters (variable, joining, constant) occupying 3-7 kilobases. Cluster arrangement can be grouped into two patterns based upon spacing between the genes in the individual clones. This arrangement is fundamentally different from that observed in higher vertebrates.

Amino Acid Sequence↗
PubMed1992

The primary structure of fatty-acid-binding protein from nurse shark liver. Structural and evolutionary relationship to the mammalian fatty-acid-binding protein family.

The primary structure of a fatty-acid-binding protein (FABP) isolated from the liver of the nurse shark (Ginglymostoma cirratum) was determined by high-performance tandem mass spectrometry (employing multichannel array detection) and Edman degradation. Shark liver FABP consists of 132 amino acids with an acetylated N-terminal valine. The chemical molecular mass of the intact protein determined by electrospray ionization mass spectrometry (Mr = 15124 +/- 2.5) was in good agreement with that calculated from the amino acid sequence (Mr = 15121.3). The amino acid sequence of shark liver FABP displays significantly greater similarity to the FABP expressed in mammalian heart, peripheral nerve myelin and adipose tissue (61-53% sequence similarity) than to the FABP expressed in mammalian liver (22% similarity). Phylogenetic trees derived from the comparison of the shark liver FABP amino acid sequence with the members of the mammalian fatty-acid/retinoid-binding protein gene family indicate the initial divergence of an ancestral gene into two major subfamilies: one comprising the genes for mammalian liver FABP and gastrotropin, the other comprising the genes for mammalian cellular retinol-binding proteins I and II, cellular retinoic-acid-binding protein myelin P2 protein, adipocyte FABP, heart FABP and shark liver FABP, the latter having diverged from the ancestral gene that ultimately gave rise to the present day mammalian heart-FABP, adipocyte FABP and myelin P2 protein sequences. The sequence for intestinal FABP from the rat could be assigned to either subfamily, depending on the approach used for phylogenetic tree construction, but clearly diverged at a relatively early evolutionary time point. Indeed, sequences proximately ancestral or closely related to mammalian intestinal FABP, liver FABP, gastrotropin and the retinoid-binding group of proteins appear to have arisen prior to the divergence of shark liver FABP and should therefore also be present in elasmobranchs. The presence in shark liver of an FABP which differs substantially in primary structure from mammalian liver FABP, while being closely related to the FABP expressed in mammalian heart muscle, peripheral nerve myelin and adipocytes, opens a further dimension regarding the question of the existence of structure-dependent and tissue-specific specialization of FABP function in lipid metabolism.

Amino Acid Sequence↗
PubMed2024

Comparative genomics illuminates karyotype and sex chromosome evolution of sharks.

Chondrichthyes is an important lineage to reconstruct the evolutionary history of vertebrates. Here, we analyzed genome synteny for six chondrichthyan chromosome-level genomes. Our comparative analysis reveals a slow evolutionary rate of chromosomal changes, with infrequent but independent fusions observed in sharks, skates, and chimaeras. The chondrichthyan common ancestor had a proto-vertebrate-like karyotype, including the presence of 18 microchromosome pairs. The X chromosome is a conversed microchromosome shared by all sharks, suggesting a likely common origin of the sex chromosome at least 181 million years ago. We characterized the Y chromosomes of two sharks that are highly differentiated from the X except for a small young evolutionary stratum and a small pseudoautosomal region. We found that shark sex chromosomes lack global dosage compensation but that dosage-sensitive genes are locally compensated. Our study on shark chromosome evolution enhances our understanding of shark sex chromosomes and vertebrate chromosome evolution.

Animals↗
PubMed1978

Visual discrimination following partial telencephalic ablations in nurse sharks (Ginglymostoma cirratum).

An instrumental conditioning task was used to examine the role of the nurse shark telencephalon in black-white (BW) and horizontal-vertical stripes (HV) discrimination performance. In the first experiment, subjects initially received either bilateral anterior telencephalic control lesions or bilateral posterior telencephalic lesions aimed at destroying the central telencephalic nuclei (CN), which are known to receive direct input from the thalamic visual area. Postoperatively, the sharks were trained first on BW and then on HV. Those with anterior lesions learned both tasks as rapidly as unoperated subjects. Those with posterior lesions exhibited visual discrimination deficits related to the amount of damage to the CN and its connecting pathways. Severe damage resulted in an inability to learn either task but caused no impairments in motivation or general learning ability. In the second experiment, the sharks were first trained on BW and HV and then operated. Suction ablations were used to remove various portions of the CN. Sharks with 10% or less damage to the CN retained the preoperatively acquired discriminations almost perfectly. Those with 11-50% damage had to be retrained on both tasks. Almost total removal of the CN produced behavioral indications of blindness along with an inability to perform above the chance level on BW despite excellent retention of both discriminations over a 28-day period before surgery. It appears, however, that such sharks can still detect light. These results implicate the central telencephalic nuclei in the control of visually guided behavior in sharks.

Animals↗
PubMed1991

Multiple prismatic calcium phosphate layers in the jaws of present-day sharks (Chondrichthyes; Selachii).

Jaws of large individuals, over 2 m in total length, of the shark species Carcharodon carcharias (great white shark) and Isurus oxyrinchus (mako shark) of the family Lamnidae, and Galeocerdo cuvieri (tiger shark) and Carcharhinus leucas (bull shark) of the family Carcharhinidae were found to have multiple, up to five, layers of prismatic calcium phosphate surrounding the cartilages. Smaller individuals of these species and other known species of living chondrichthyans have only one layer of prismatic calcium phosphate surrounding the cartilages, as also do most species of fossil chondrichthyans. Two exceptions are the fossil shark genera Xenacanthus and Tamiobatis. Where it is found in living forms, this multiple layered calcification does not appear to be phylogenetic, as it appears to be lacking in other lamnid and carcharhinid genera and species. Rather it appears to be functional, only appearing in larger individuals and species of these two groups, and hence may be necessary to strengthen the jaw cartilages of such individuals for biting.

Animals↗