Comparative analysis of the mitochondrial DNA control region in cyprinids with different ploidy level

Abstract

The comprehensive analysis of the complete mitochondrial DNA control region (mtDNA-CR) sequences from the different ploidy level cyprinid fish was made. The mtDNA-CR sequences for allotriploid crucian carp and allotriploid common carp were amplified by the polymerase chain reaction (PCR) and the amplified products were sequenced. The mtDNA-CR sequences from diploids, such as the red crucian carp, common carp, Japanese crucian carp, and zebrafish to polyploids, such as the allotetraploid, allotriploid crucian carp, and allotriploid common carp, were compared and analyzed. The extended terminal associated sequences (ETAS), central conserved sequence blocks (CSB-F, CSB-E, CSB-D), conserved sequence blocks (CSB-1, CSB-2, CSB-3), and putative promoters of the mtDNA-CR in the seven cyprinid fish were observed. Our data were consistent with the opinion of three domains (extended terminal associated sequences, central, conserved sequence block domains) within the mtDNA-CR in the mammals. The most conserved region in the mtDNA-CR was the central conserved sequence block domain (34.06% of nucleotide positions variable), whereas in the ETAS and CSB domains, 66.91% and 40.00% of nucleotide positions were variable, respectively. Based on the comparative analysis of the mtDNA-CR in cyprinids with different ploidy level, the consensus sequences of functional conserved units of the mtDNA-CR in cyprinids were identified. These results provided the useful and important information for the further study of the mtDNA-CR structure in fish. The similarities of the mtDNA-CR sequences between the allotriploid crucian carp and allotriploid common carp and their female parents were higher than those between allotriploid crucian carp and allotriploid common carp and their male parents, providing the direct evidence of the maternal inheritance of the mtDNA-CR in the allotriploid crucian carp and allotriploid common carp.