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At least 199 records · Page 11Linked to original sources
PubMed1995

Analysis of human remains recovered from a shark.

Trauma caused by marine scavengers and predators, especially sharks, is not well known. This paper describes the effect of shark attack on human remains. They were found in the stomach of a tiger shark caught by fishermen near Hollywood Beach, Florida. The remains belonged to a white male in his late twenties or early thirties with a stature of 175 cm. The damages to the skeleton and the association of these damages with the behaviours of tiger sharks is also analyzed. The trauma affecting long bones are circular punctures around the epiphyseal ends. Other changes include unique crescent shape grooves horizontal to the shaft of the bone. Although all of the bones are affected, none of them is fractured or crushed, suggesting that the body parts are first dismembered and then swallowed and digested.

Adult↗
PubMed2005

Chemical characterisation of eggs from deep-sea sharks.

The chemical characterisation and nutritional value of eggs from the five deep-sea sharks leafscale gulper shark (Centrophorus squamosus), greater lantern shark (Etmopterus princeps), longnose velvet dogfish (Centroscymnus crepidater), Portuguese dogfish (Centroscymnus coelolepis) and black dogfish (Centrocyllium fabricii) captured at Hatton Bank in the North Atlantic were examined. The chemical composition was quite similar for all the eggs studied. The dominant fatty acid in all the eggs was the monounsaturated fatty acid C18:1, which varied from 27-39%. The eggs had a relatively high content of C16:0 (13.0-18.5%) and C22:6n-3 (10.3-15.1%). The two main lipid classes in the eggs were triacylglycerols (36-55%) and phospholipids (34-41%). The eggs had high amounts of vitamin A and E. The shark eggs were particularly rich in the amino acids aspartic acid, glutamic acid, leucine and arginine.

Amino Acids↗
PubMed2026

Antibody diversification in cartilaginous fishes: Mechanistic insights from the nurse shark and comparative perspectives across jawed vertebrates.

Antibody diversity in vertebrates arises through the coordinated actions of V(D)J recombination and somatic hypermutation (SHM). Cartilaginous fishes occupy a key phylogenetic position as the sister lineage to bony vertebrates and therefore provide important comparative insights into the evolution of adaptive immunity. This review focuses on the nurse shark (Ginglymostoma cirratum) as a representative model for examining antibody-diversification mechanisms in cartilaginous fishes. Shark immunoglobulin genes exhibit a multicluster organization, while immunoglobulin new antigen receptor (IgNAR), a heavy-chain-only isotype, contains a single variable domain with an extended complementarity-determining region 3 (CDR3) that can be stabilized by non-canonical disulfide bonds. These structural features, together with intracluster multi-D V(D)J recombination and distinctive SHM characterized by single and tandem substitutions and insertions/deletions, contribute to antibody diversification in sharks. By comparing cartilaginous fishes, ray-finned fishes, and mammals, this review highlights lineage-specific combinations of immunoglobulin gene organization, recombination, mutational processing, and affinity maturation. Within the heuristic framework proposed here, shark and mammalian systems are described as emphasizing "breadth-first" repertoire generation and "precision-first" affinity optimization, respectively. These terms indicate relative mechanistic emphases rather than mutually exclusive categories or sequential evolutionary stages, while ray-finned fishes exhibit a distinct combination of genomic organization and mutational features. Investigating antibody diversification in cartilaginous fishes not only advances our understanding of vertebrate immune evolution but also provides structural and mechanistic insights that may inform the development of engineered antibodies based on the IgNAR scaffold.

Antibody diversity↗
PubMed2005

Feeding ecology of five commercial shark species of the Celtic Sea through stable isotope and trace metal analysis.

In order to trace their feeding habits, stable carbon and nitrogen isotope ratios (delta15N and delta13C), as well as trace metal concentrations (Zn, Cd, Fe, Cu, Se and Hg) were analysed in the tissues of five commercial shark species from the Celtic Sea: the tope shark Galeorhinus galeus, the black-mouthed catshark Galeus melastomus, the starry smooth hound Mustelus asterias, the spiny dogfish Squalus acanthias and the lesser-spotted dogfish Scyliorhinus canicula. Our results were compared to previously described stomach contents and isotopic composition of potential preys. Isotopic ratio delta15N suggested that tope sharks fed at a higher trophic level (16.7 per thousand in the muscle) than the other species, reflecting its piscivorous diet. The lower values of spiny dogfish (11.6 per thousand in the muscle) might be explained, amongst other things, by either its migratory behaviour or its preference for preys from lower trophic levels. Cd and Hg were correlated with isotopic ratios delta13C and delta15N, and were shown to be diet-related whereas Zn, Fe and Cu seemed much more linked to species-specific metabolism. Although this multidisciplinary approach is revealed as a useful tool for the study of shark ecology, the lack of known trophic fractionation suggests that isotopic data be compared to traditional diet analyses.

Animals↗
PubMed2004

Oral intake of shark liver oil modifies lipid composition and improves motility and velocity of boar sperm.

The natural ether-lipids 1-O-alkylglycerols (alkyl-Gro) from shark liver oil improve boar sperm motility and fertility in vitro. We examined the effects of oral shark liver oil on motility and velocity parameters of sperm together with modifications of lipid composition. Eleven boars were used as control and 11 were fed with 40 g/day for 28 days and sperm was collected on Days 0, 14 and 28 in control and treated groups. After 28 days treatment, sperm motility was improved by 2.9% as well as velocity parameters (curvilinear velocity +10.75%, progressive velocity +18.8% and average path velocity +13.5%) and sperm lipid composition was modified as follows: alkyl-Gro with saturated chains were increased (C16:0 +40.1%, C18:0 +87.2%) while alkyl-Gro with unsaturated chains remained absent, as in the control group, despite the prominence of C18:1 and C16:1 in shark liver oil. The treatment also resulted in an overall increase in the proportion of n - 3 and n - 6 polyunsaturated fatty acids in sperm lipids with a prominent increase of docosahexaenoic acid over time (18.9 +/- 1.34% at Day 0 to 25.7 +/- 1.11% at Day 28) and compared to control (25.7 +/- 1.11% for treated versus 16.1 +6/- 0.81 % for control at Day 28, respectively). These data demonstrate the influence of lipid intake on boar sperm composition and functions and suggest that oral intake of shark liver oil might improve reproduction.

Animals↗
PubMed1999

The occurrence, distribution and pathology associated with gnathiid isopod larvae infecting the epaulette shark, Hemiscyllium ocellatum.

Gnathiid isopod praniza larvae were found to infect the epaulette shark Hemiscyllium ocellatum. All sharks carried larvae on their external body surface, with the preferred attachment site in both sexes around the cloaca (P<0.05). The claspers were the second site of preference in male sharks. Within the buccal and branchial cavities, about 16% of larvae were attached to the roof and floor of the mouth and 84% attached to the gills. A significant positive correlation existed between larval number and fish size. Histological examination showed that larval attachment in the buccal cavity elicited variable responses, the most severe being a loss of epithelium and compression of underlying tissue. No host cellular response or tissue proliferation was observed. Praniza attached preferentially to the efferent side of gill filaments (relative to blood flow), and caused loss of epithelium, compression of tissue, and a small amount of connective tissue proliferation. Attachment to the gill septum or to the afferent side of the gill filament caused lamellar disruption, a cellular inflammatory response, and connective tissue proliferation. Scanning electron microscopy showed little obvious praniza-induced gill damage, other than localised tissue distortion to form "pockets" around larvae attached between filaments. The results suggest that praniza larvae do not cause sufficient tissue damage to adversely affect the health of this shark species.

Animals↗
PubMed2002

Plastic debris collars on juvenile carcharhinid sharks (Rhizoprionodon lalandii) in southwest Atlantic.

Three juvenile Brazilian sharpnose sharks (Rhizoprionodon lalandii) caught in gillnets in southeast Brazil, southwest Atlantic, were found with plastic debris rings around their gill or mouth region. The rings caused severe abrasion on the sharks' tissues as the animal grew, the collars probably hampering normal feeding and/or ventilation since two of the collared individuals were emaciated. The rings were identified as detachable lid parts from plastic bottles, likely thrown overboard by fishery and/or recreation boats. As several carcharhinid shark species dwells and reproduce in shallow waters, the impact of discarded plastic debris likely is greater on this shark type.

Animals↗
PubMed1982

Phylogeny of immunoglobulin structure and function. XIV. Peptide map and amino acid composition studies of shark antibody light chains.

Light chains from antibodies to the streptococcal A-variant carbohydrate from individual nurse sharks were compared by peptide maps of tryptic digests and amino acid compositions. Although the amino acid compositions of the different chains were quite similar, considerable differences as well as similarities were demonstrable on peptide maps. The peptide maps were interpreted as indicating that shark L chains likely have constant and variable regions as seen in the immunoglobulins of higher animals. Furthermore the unique peptides characteristic of different L chains support the hypothesis that nurse sharks, as a species, possess a relatively large number of different L chain amino acid sequences which are compatible with antibody binding sites to the streptococcal antigen. Hence the repetoire of nurse shark antibody combining sites to this antigen appears to be quite extensive.

Amino Acid Sequence↗
PubMed2001

Isolation of the new antigen receptor from wobbegong sharks, and use as a scaffold for the display of protein loop libraries.

The new antigen receptor (NAR) from nurse sharks consists of an immunoglobulin variable domain attached to five constant domains, and is hypothesised to function as an antigen-binding antibody-like molecule. To determine whether the NAR is present in other species we have isolated a number of new antigen receptor variable domains from the spotted wobbegong shark (Orectolobus maculatus) and compared their structure to that of the nurse shark protein. To determine whether these wNARs can function as antigen-binding proteins, we have used them as scaffolds for the construction of protein libraries in which the CDR3 loop was randomised, and displayed the resulting recombinant domains on the surface of fd bacteriophages. On selection against several protein antigens, the highest affinity wNAR proteins were generated against the Gingipain K protease from Porphyromonas gingivalis. One wNAR protein bound Gingipain K specifically by ELISA and BIAcore analysis and, when expressed in E. coli and purified by affinity chromatography, eluted from an FPLC column as a single peak consistent with folding into a monomeric protein. Naturally occurring nurse shark and wobbegong NAR variable domains exhibit conserved cysteine residues within the CDR1 and CDR3 loops which potentially form disulphide linkages and enhance protein stability; proteins isolated from the in vitro NAR wobbegong library showed similar selection for such paired cysteine residues. Thus, the New Antigen Receptor represents a protein scaffold with possible stability advantages over conventional antibodies when used in in vitro molecular libraries.

Adhesins, Bacterial↗
PubMed2001

Cloning and characterization of tissue inhibitor of metalloproteinase-3 (TIMP-3) from shark, Scyliorhinus torazame.

We cloned the full-length cDNA encoding TIMP-3 from the cartilage of cloudy dogfish, Scyliorhinus torazame. The entire open reading frame was composed of 645 nucleotides and 214 residues including 12 conserved cysteines and asparagine-184, a putative site for N-linked sugars. It showed about 72% identity to those of other species based on the deduced amino acid sequence. The mRNA of shark TIMP-3 were expressed abundantly in brain and cartilage tissues. To investigate the roles of shark TIMP-3, an expression vector was constructed and transfected into HT1080 human fibrosarcoma cells. Overexpression of shark TIMP-3 reduced the activity of MMP-2 in gelatin zymography. Through human Alu PCR based CAM assay, we also confirmed that shark TIMP-3 transfected HT1080 cells had less intravasation effects.

Amino Acid Sequence↗
PubMed1998

Occurrence of a novel collagen with three distinct chains in the cranial cartilage of the squid Sepia officinalis: comparison with shark cartilage collagen.

A unique collagen with three distinct chains, was purified from the cranial cartilage of the squid Sepia officinalis, by pepsinisation and salt precipitation and compared with shark cartilage collagen. These chains, which were different from the known cartilage collagen chains, were referred as C1, C2 and C3, had approximate molecular weights of 105 kDa, 115 kDa and 130 kDa, respectively, and were present in a ratio of 3:2:1, suggestive of two molecules of composition, [(C1)2C2] and [C1C2C3]. These collagens were purified by fractionation at acid and neutral pH, and by ammonium sulfate precipitation. Solubility data indicated that this collagen was more crosslinked than the type I collagen isolated from cartilage of shark, Carcharius acutus. In vitro fibrillogenesis revealed that the sepia collagen formed denser aggregates, as compared to shark collagen, and was stabilised by a higher degree of carbohydrate association. Polyclonal antisera raised against shark collagen was also reactive against the sepia collagens, while the converse was not true, indicating the high immunospecificity of the latter. These results demonstrate collagen polymorphism in an invertebrate cartilage and may hold significance in understanding tissue calcification and molecular evolution. Further, these collagens may represent ancestral forms of vertebrate minor collagens like typeV/XI.

Animals↗
PubMed2001

Review: Analysis of the evolutionary convergence for high performance swimming in lamnid sharks and tunas.

Elasmobranchs and bony fishes have evolved independently for more than 400 million years. However, two Recent groups, the lamnid sharks (Family Lamnidae) and tunas (Family Scombridae), display remarkable similarities in features related to swimming performance. Traits separating these two groups from other fishes include a higher degree of body streamlining, a shift in the position of the aerobic, red, locomotor muscle that powers sustained swimming to a more anterior location in the body and nearer to the vertebral column, the capacity to conserve metabolic heat (i.e. regional endothermy), an increased gill surface area with a decreased blood-water barrier thickness, a higher maximum blood oxygen carrying capacity, and greater muscle aerobic and anaerobic enzyme activities at in vivo temperatures. The suite of morphological, physiological, and biochemical specializations that define "high-performance fishes" have been extensively characterized in the tunas. This review examines the convergent features of lamnid sharks and tunas in order to gain insight into the extent that comparable environmental selection pressures have led to the independent origin of similar suites of functional characteristics in these two distinctly different taxa. We propose that, despite differences between teleost and elasmobranch fishes, lamnid sharks and tunas have evolved morphological and physiological specializations that enhance their swimming performance relative to other sharks and most other high performance pelagic fishes.

Adaptation, Biological↗
PubMed1976

Conformation of immunoglobulin M. 2. Nanosecond fluorescence depolarization analysis of segmental flexibility in anti-epsilon-l-dimethylamino-5-naphthalenesulfonyl-L-lysine anti-immunoglobulin from horse, pig, and shark.

The rotational motions of immunoglobulin M (IgM) were investigated by the nanosecond fluorescence depolarization technique. The fluorophore epsilon-1-dimethylamino-5-naphthalenesulfonyl-L-lysine (DNS-lysine) was specifically bound in the combining sites of anti-DNS IgM antibodies from the horse, pig, and nurse shark. Fluorescence lifetime analysis showed the presence of a long lifetime component (21-27 ns) with antibodies from all three species. With the mammalian antibodies, the fluorophore appeared to be rigidly bound in the combining sites as judged by the presence of induced circular dichroism of DNS-lysine (equine antibodies) and single exponential anisotropy decay of the isolated Fabmu fragments (equine and porcine antibodies). The small amount of available purified nurse shark antibody did not allow preparation of fragments or induced circular dichroism measurements to directly determine rigidity of fluorophore binding. However, at least some of the hapten must have been rigidly bound since long rotational correlation times were measured for the shark DNS-lysine-anti-DNS complexes. When the emission anisotropy of the fluorophore-anti-DNS IgM complexes was measured as a function of time, it was found that all three antibody species exhibited restricted segmental flexibility in the nanosecond time range. Moreover, when the equine anti-DNS IgM was exposed to 1 M acetic acid for 1 h, the antibody underwent a conformational change which resulted in an increase in its overall flexibility. Comparison of the rotational correlation times of native equine IgM and of proteolytic fragments indicated that flexibility of IgM consists of either hindered rotation of the Fab'mu segment or a combination of at least two modes of motion: rotation of Fabmu and/or Fab'mu and bending of the entire (Fab')2mu region as a unit. Similar modes of flexibility also occur in native porcine IgM. In acid exposed equine IgM, the major contribution to depolarization is from independent rotation or wagging of the Fab'mu segments. Thus, acid apparently causes a conformational change in or near the Cmu2 domains. In contrast, flexibility in nurse shark IgM appears to involve only bending of (Fab')2mu as a unit. Our results suggest that segmental flexibility is an essential functional feature of all IgM antibodies and that control of this flexibility through domain interactions may play an important role in such conformationally sensitive functions as complement fixation.

Acetates↗
PubMed1996

Heavy-chain variable regions in carcharhine sharks: development of a comprehensive model for the evolution of VH domains among the gnathanstomes.

We determined the sequence of 18 DNA clones encoding VH regions of sandbar shark and bull shark. All of these sequences exhibit key structural coding features characteristic of known VH genes of higher vertebrates. These VH sequences disclosed considerable diversity, and can be divided into six families according to the criterion of 80% DNA sequence identity. The overlapping of some VH gene clones to two or more families is a particular feature found in carcharhine sharks, which suggests that VH diversification is a continuing process. The basic sequence patterns of heavy-chain V regions found in all representative gnathanstomes and in VH of the shark heavy immunoglobulin IgW provides evidence for selection of canonical residues in all VH structures. Elasmobranch VH sequences can be divided into two classes or clans, one comprising the 'classical' VH set and the other comprising VHS related to those of IgW (V omega). Phylogenetic analyses place the VH cluster as the root of all the classic VHS and indicates that the V omega set is most probably that of the primordial heavy chain.

Amino Acid Sequence↗
PubMed1993

Genomic clone for sandbar shark lambda light chain: generation of diversity in the absence of gene rearrangement.

While the general structure of immunoglobulin chains has remained relatively unchanged throughout evolution, the organization of the genes encoding these molecules differs substantially. To understand how the rearranging immunoglobulin system arose, it is necessary to examine living representatives of the most early vertebrate phyla. Elasmo-branches, which include the sharks, skates, and rays, are the most primitive phylogenetic class of vertebrates from which immunoglobulin DNA sequences have been obtained. In the sandbar shark (Carcharhinus plumbeus), the genes are arranged in individual clusters in which a single variable (V), joining (J), and constant (C) region gene, along with upstream regulatory elements, span a distance of approximately 4.4 kb or approximately 5.8 kb. We report the complete sequence of a genomic clone encoding sandbar shark lambda light chain. A unique finding of our study is that the V and J genes are fused in the germ line. Three additional clones have been shown by DNA sequencing to also have fused V and J genes. The four clones have complementarity-determining regions 3 of various lengths and amino acid sequence variability similar to the products of rearranged genes. Furthermore, analysis by polymerase chain reaction technology revealed an additional 26 genomic clones demonstrating fusion of the V and J segments. Therefore, VJ fusion is the prominent organizational feature of sandbar shark immunoglobulin light chain genes. This finding raises questions concerning the necessity of recombination to produce an antibody repertoire capable of reacting against a diverse array of antigens.

Amino Acid Sequence↗
PubMed2001

A shark antibody heavy chain encoded by a nonsomatically rearranged VDJ is preferentially expressed in early development and is convergent with mammalian IgG.

In most vertebrate embryos and neonates studied to date unique antigen receptors (antibodies and T cell receptors) are expressed that possess a limited immune repertoire. We have isolated a subclass of IgM, IgM(1gj), from the nurse shark Ginglymostoma cirratum that is preferentially expressed in neonates. The variable (V) region gene encoding the heavy (H) chain underwent V-D-J rearrangement in germ cells ("germline-joined"). Such H chain V genes were discovered over 10 years ago in sharks but until now were not shown to be expressed at appreciable levels; we find expression of H(1gj) in primary and secondary lymphoid tissues early in life, but in adults only in primary lymphoid tissue, which is identified in this work as the epigonal organ. H(1gj) chain associates covalently with light (L) chains and is most similar in sequence to IgM H chains, but like mammalian IgG has three rather than the four IgM constant domains; deletion of the ancestral IgM C2 domain thus defines both IgG and IgM(1gj). Because sharks are the members of the oldest vertebrate class known to possess antibodies, unique or specialized antibodies expressed early in ontogeny in sharks and other vertebrates were likely present at the inception of the adaptive immune system.

Amino Acid Sequence↗
PubMed1998

Characteristic hexasaccharide sequences in octasaccharides derived from shark cartilage chondroitin sulfate D with a neurite outgrowth promoting activity.

A mouse brain chondroitin sulfate (CS) proteoglycan, DSD-1-PG, bears the DSD-1 epitope and has neurite outgrowth promoting properties. Shark cartilage CS-C inhibits the interactions between the DSD-1-specific monoclonal antibody 473HD and the CS chains of the DSD-1-PG, which is expressed on the mouse glial cells (Faissner, A., Clement, A., Lochter, A., Streit, A., Mandl, C., and Schachner, M. (1994) J. Cell Biol. 126, 783-799). On the other hand, several hexasaccharides isolated from commercial shark cartilage CS-D, which contains a higher proportion of characteristic D units (GlcUA(2-sulfate)beta1-3GalNAc(6-sulfate)) as compared with CS-C, has the A-D tetrasaccharide sequence composed of an A disaccharide unit (GlcUAbeta1-3GalNAc(4-sulfate)) and a D disaccharide unit (Nadanaka, S. and Sugahara, K. (1997) Glycobiology 7, 253-263). In this study, the biological activities and the structure of shark cartilage CS-D were investigated. CS-D inhibited the interactions between monoclonal antibody 473HD and DSD-1-PG and also promoted neurite outgrowth of embryonic day 18 hippocampal neurons. Eight octasaccharide fractions were isolated from CS-D after partial digestion with bacterial chondroitinase ABC by means of gel filtration chromatography and anion-exchange high performance liquid chromotography to investigate the frequency and the arrangement of the A-D tetrasaccharide unit in the polymer sequence. Structural analysis performed by a combination of enzymatic digestions with 500-MHz 1H NMR spectroscopy demonstrated that the isolated octasaccharides shared the common core structure DeltaHexAalpha1-3GalNAcbeta1-4(GlcUAbeta1-3GalNAc)3 with four, five, and six sulfate esters at various hydroxyl groups in different combinations. In the structure, DeltaHexA and GlcUA represent 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid and glucuronic acid, respectively. No D-D tetrasaccharide sequence was found, and discrete D disaccharide units were demonstrated exclusively as A-D tetrasaccharide units in either an A-D-A or an A-D-C hexasaccharide sequence in the five octasaccharides that represented about 5.0% (w/w) of the starting polysaccharides (C denotes the disaccharide GlcUAbeta1-3GalNAc(6-sulfate)). It remains to be determined whether such characteristic hexasaccharide sequences present in shark cartilage CS-D serve as functional domain structures recognized by some protein ligands.

Animals↗
PubMed2004

Sequence, evolution and tissue expression patterns of an epidermal type I keratin from the shark Scyliorhinus stellaris.

From the shark Scyliorhinus stellaris we cloned and sequenced a cDNA encoding a novel type I keratin, termed SstK10. By MALDI-MS peptide mass fingerprinting of cytoskeletal proteins separated on polyacrylamide gels, we assigned SstK10 to a 46-kDa protein which is the major epidermal type I ("IE") keratin in this fish and is specifically expressed in stratified epithelia. In a phylogenetic tree based on type I keratin sequences and with lamprey keratins applied as outgroup, SstK10 branches off in a rather basal position. This tree strongly supports the concept that teleost keratins and tetrapod keratins resulted from two independent gene radiation processes. The only exception is human K18 because its orthologs have been found in all jawed vertebrates (Gnathostomata) studied; in the tree, they form a common, most early branch, with the shark version, SstK18, in the most basal position. Thus, the sequences of SstK10 and SstK18 also favor the classical view of vertebrate evolution that considers the cartilaginous fishes as the most ancient living Gnathostomata. To determine the overall expression patterns of epidermal ("E") and simple epithelial ("S") keratins in this shark, we furthermore tested a panel of monoclonal anti-keratin antibodies by immunofluorescence microscopy of frozen tissue sections, and in immunoblots of cytoskeletal preparations, demonstrating that immunodetection of specific keratins is a convenient method to characterize epithelial tissues in shark.

Amino Acid Sequence↗