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Molecular cloning of the myelin basic proteins in the shark, Squalus acanthias , and the ray, Raja erinacia
Author(s) -
Spivack W. D.,
Zhong N.,
Salerno S.,
Saavedra R. A.,
Gould R. M.
Publication year - 1993
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490350602
Subject(s) - squalus acanthias , gene isoform , biology , exon , complementary dna , raja , amino acid , peptide sequence , microbiology and biotechnology , myelin basic protein , gene , genetics , biochemistry , myelin , paleontology , neuroscience , central nervous system
Myelin basic proteins (MBPs) are a family of alternatively spliced isoforms present in myelin sheaths of most vertebrates. A reverse transcriptase‐polymerase chain reaction (RT‐PCR) approach was used to clone MBP isoforms in species representing two superorders of elasmobranchs: Squalus acanthias , representing Squalomorph sharks, and Raja erinacia , representing Batoidea rays. Two products were generated from each species. The larger product encoded a 155 amino acid protein, the same size as MBPs from two Galeomorph sharks, Heterodontus francisci and Carcharhinus obscurus , which, based upon alignment with other vertebrate MBPs, contained six of the seven MBP exons; only exon II was absent. The smaller product encoded a 141 amino acid protein that lacked exon II and exon V. There were 26 and 30 nucleotide differences between Squalus and Heterodontus , and Raja and Heterodontus , respectively. Sequences from Squalus and Raja were far more similar, having only five nucleotide differences. Both isoforms of elasmobranch MBP contain 18.5% basic (lysine plus arginine) amino acids, compared with 17.5% in mammalian MBPs comprised of the corresponding exons. Northern blot analysis of whole brain total RNA revealed a single band of 2.5 kb in Squalus , and three bands of 1.2, 1.4, and 2.3 kb in Raja . The finding that MBPs of a Squalomorph shark and a Batoidea ray are closer to one another than either is to the Galeomorph sharks suggests that MBP sequence information may prove useful in classifying modern day Chondrichthytes. © 1993 Wiley‐Liss, Inc.