Cloning And Phylogenetic Relationship Research In Guizhou Nuogu Pig Mitochondrial DNA

We obtained the complete mitochondrial genome of Nuogu pig by DNA sequencing based on the PCR fragments of 10 primers we designed (Accession number DQ466081 in GenBank). The complete mitochondrial genome is 16,673 base pairs (bp) in length. It contains genes for 22 transfer RNAs, 2 ribosomal RNAs and 13 protein-coding genes, and it also has a control region sequence (D-loop), which is very similar to that of other mammals. We also cloned other 16 Nuogu pigs D-loop, and found that the large length variation between D-loop regions .The copies of the tandem repeats diversify in the number maybe caused length variation by replication slippage. The phenomenon of heteroplasmy is produced by paternal inheritance by any possibility.Using the mitochondrial sequences of some species obtained from the GenBank, we discussed the phylogenetic relationships of pig among the 5 eutherian species and two European pigs (one Landrace pig and one Sweden pig). Based on the comparing sequences of 13 protein-coding genes and rRNA genes, we suggest that the evolutiona ry separation between Nuogu pig and two European pigs was 807000 years ago. We support there is a closer relationship between the pig and cow than that between either of these species and fin whale. The evolutionary separation of pig and cow occurred about 53-60 million years ago.6 haplotypes were obtained from 17 mtDNA control region sequences. Though genetic diversity in Nuogu pig was not low , the genetic divergences inter-population from different localities showed significant difference, and there shows genetic isolation among inter-population., which means founder effects had appearance in Nuogu history.Based on the partial control region sequences of Nuogu Seven haplotypes and other reported breeds in GeneBank, the neighbor joining method was adopted to examine the Nuogu phylogenetic relationship. We found that Nuogu pigs have a closely relationship with Wuzhishan, Kele, Xiang, Meishan which suggests a large variations between Nuogu pigs in their maternal lineages. This result show some correspondences between geographic and morphology origin. We made a preliminary discussion on Nuogu SRY gene, and found suidae has a closer relationship withbovidae. The result is in accord with the popular theory.