Molecular Biology and Evolution, Vol 8, 515-529, Copyright © 1991 by Society for Molecular Biology and Evolution
C De Giorgi, C Lanave, MD Musci and C Saccone
From the stirodont Arbacia lixula we determined the sequence of 5,127
nucleotides of mitochondrial DNA (mtDNA) encompassing 18 tRNAs, two
complete coding genes, parts of three other coding genes, and part of the
12S ribosomal RNA (rRNA). The sequence confirms that the organization of
mtDNA is conserved within echinoids. Furthermore, it underlines the
following peculiar features of sea urchin mtDNA: the clustering of tRNAs,
the short noncoding regulatory sequence, and the separation by the ND1 and
ND2 genes of the two rRNA genes. Comparison with the orthologous sequences
from the camarodont species Paracentrotus lividus and Strongylocentrotus
purpuratus revealed that (1) echinoids have an extra piece on the amino
terminus of the ND5 gene that is probably the remnant of an old leucine
tRNA gene; (2) third- position codon nucleotide usage has diverged between
A. lixula and the camarodont species to a significant extent, implying
different directional mutational pressures; and (3) the
stirodont-camarodont divergence occurred twice as long ago as did the P.
lividus-S. purpuratus divergence.
ORIGINAL ARTICLE
Mitochondrial DNA in the sea urchin Arbacia lixula: evolutionary inferences from nucleotide sequence analysis [published erratum appears in Mol Biol Evol 1991 Sep;8(5):742]
Dipartimento di Biochimica e Biologia Molecolare, University of Bari, Italy.
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