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At least 883 records · Page 49Linked to original sources
PubMed1986

Isolation and characterization of Cu,Zn superoxide dismutase of the shark Prionace glauca.

A Cu,Zn superoxide dismutase was purified for the first time from an elasmobranch species (Prionace glauca) and showed the following differences with respect to other animal superoxide dismutases. The enzyme displays a low isoelectric point. The enzyme activity is unusually independent of ionic strength. The isolated enzyme has 30% of its copper in the reduced state.

Amino Acids↗
PubMed1980

High ionic strength: its significance in immunosurveillance against tumor cells in sharks and rays (elasmobranchs).

It is postulated that the rarity of tumors in elasmobranchs is due to the high ionic strength in their tissues, which is equivalent to a high body temperature. Such conditions should lead to the elimination of variable antigenicity and 100% immune surveillance. The basis for this theory is that the repressor molecular for mitosis, not binding to its operator site cannot bind anywhere.

Animals↗
PubMed2005

Extensive paraphylies within sharks of the order Carcharhiniformes inferred from nuclear and mitochondrial genes.

Using nuclear coding and mitochondrial ribosomal genes we try to clarify relationships within Carcharhiniformes with special focus on the two most problematic groups: scyliorhinids and triakids. The mitochondrial aligned sequences are 1542 bp long, and include principally portion of 16S rRNA gene. They are obtained for two outgroup species and 43 Carcharhiniformes species, covering 5 of the 8 families and 15 of the 48 genera of the order. The nuclear RAG1 sequences are 1454 bp long, and are obtained for 17 species representative of the diversity of all species sampled. We used Maximum Parsimony and Maximum Likelihood criteria for tree reconstruction. Paraphylies within the family Scyliorhinidae was proposed for the first time by Maisey [Zool. J. Linn. Soc. 82, 33, 1984] in a morphological cladistic analysis. This result has never been proposed again until recently from molecular phylogenies [Mol. Phylogenet. Evol. 31, 214, 2004]. Here, independent and simultaneous analyses of nuclear and mitochondrial data are congruent in supporting the paraphyly of scyliorhinids. Two groups of scyliorhinids are obtained, thoroughly in line with discrimination proposed by previous authors, based on presence/absence of supraorbital crests on the chondrocranium. The first group (Scyliorhinus+Cephaloscyllium) is basal within carcharhiniforms and the second group (Apristurus+Asymbolus+Cephalurus+Galeus+Parmaturus) is sister group of all the other families investigated (Carcharhinidae, Proscyllidae, Pseudotriakidae, and Triakidae). The paraphyly of triakids appeared probable but more investigations are needed. In conclusion several independent morphological and molecular phylogenetic studies support paraphyly within scyliorhinids. So we propose a new classification for the group, with the redefinition of the family Scyliorhinidae sensu stricto and the resurrection of the family Pentanchidae with a new definition.

Animals↗
PubMed2002

Telencephalo-habenulo-interpeduncular connections in the brain of the shark Chiloscyllium arabicum.

The telencephalo-habenulo-interpeduncular connections have been studied in the brain of the cartilaginous fish Chiloscyllium arabicum. In addition to telencephalic and diencephalic projections to the habenula and to habenulo-interpeduncular projection, the presence of a direct telencephalo-interpeduncular connection confirmed some homologies of this system in cartilaginous fishes with actinopterigian fishes and land vertebrates.

Animals↗