MOLECULAR-CLONING AND COMPLETE NUCLEOTIDE-SEQUENCE OF THE REPEATED UNIT AND FLANKING GENE OF THE SCALLOP PECTEN-MAXIMUS MITOCHONDRIAL-DNA -PUTATIVE REPLICATION ORIGIN FEATURES
A. Rigaa et al., MOLECULAR-CLONING AND COMPLETE NUCLEOTIDE-SEQUENCE OF THE REPEATED UNIT AND FLANKING GENE OF THE SCALLOP PECTEN-MAXIMUS MITOCHONDRIAL-DNA -PUTATIVE REPLICATION ORIGIN FEATURES, Journal of molecular evolution, 41(2), 1995, pp. 189-195
In the bivalve mollusc Pecten maximus, the size of the mitochondrial D
NA molecules ranges from 20 to 25.8 kbp. This variability is mainly co
rrelated with the occurrence of a variable domain composed with two to
five 1.6-kbp repeated units tandemly arrayed in the genome. DNA fragm
ents spanning the 1,586-base-pair-long repeated element and the neares
t flanking gene have been cloned and sequenced. This sequence was anal
yzed regarding its base composition and potential secondary structures
. The repeated unit domain was positioned and oriented with regard to
the known flanking gene. It ends 2 base pairs upstream relative to the
beginning of the tRNA(gly) gene. The peculiar properties of the repea
ted unit were compared with those of the 1,442-bp repeated element fou
nd in the mitochondrial genome of the deep sea scallop Placopecten mag
ellanicus. This comparison provided evidence for the absence of nucleo
tide conservation, except for a small sequence engaged in a secondary
structure, but argued for a strong pressure maintaining domains with s
pecific nucleotide content. A possible role for the conserved sequence
is discussed.