Abstract
The human mitochondrial DNA is a 16569 bp closed, circular molecule that was sequenced and mapped. The D-loop of mitochondrial DNA is a major control site for mtDNA expression and it is important in maternal inheritance. This region in different population is vary and contains essential transcription and replication elements and it could be used for detection of mother inheritance, and human evolution. The aim of present study was to determine the D-loop region polymorphism in Bakhtiarian population in southwest Iran. The blood samples of 168 healthy people of Bakhtiarian population in Iran were collected and total DNA was extracted and then, mtDNA D-loop region was amplified by PCR using specific primers. Restriction fragment length polymorphism (RFLP) was analyzed in PCR products by HaeIII and AluI restriction endonuclease. Amplified fragments for mtDNA D-loop region on 1% agarose gel revealed a fragment of about 1024 bp. The results of this study showed 5 restriction patterns for HaeIII enzyme (with 1 heteroplasmy) and 2 restriction patterns for AluI enzyme (with 2 heteroplasmies) in Bakhtiarian population. The findings showed a low level of genetic polymorphism in D-loop region and it is related to high kinship marriages and low range of migration in Bakhtiarian population. Keywords: mtDNA, D-loop region, RFLP, Polymorphism, Bakhtiarin population, Iran
Highlights
The human mitochondrial DNA is a circular double-stranded molecule, and was first fully sequenced in 1981 by Anderson et al (Hoong & Lek, 2005)
The Displacement loop (D-loop) is the location of mitochondrial transcription promoters and it is the major control site for mitochondrial DNA (mtDNA) expression because it contains the leading-strand for origin of replication and major promoters for transcription (Miyazono et al, 2002). mtDNA replication begins in the D-loop resulting in the formation of a displacement loop with a newly synthesized heavy, or H, strand of about 700nt known as 7S DNA (Sbisa et al, 1997)
Digestion of amplified fragments of mtDNA D-loop region by HaeIII and AluI restriction endonuclease and their frequency are listed in tables 1 and 2
Summary
The human mitochondrial DNA (mtDNA) is a circular double-stranded molecule, and was first fully sequenced in 1981 by Anderson et al (Hoong & Lek, 2005). MtDNA is present in high copy number in human cells, with high mutation rate, haplogroup, without recombination and maternal inheritance (Sbisa et al, 1997; Tsutsumi et al, 2006) These specifications make mtDNA easier to obtain for analysis, and make it the molecule of choice for analyzing ancient DNA and for certain forensic DNA applications (Witas & Zawicki, 2004; Tsutsumi et al, 2006). MtDNA replication begins in the D-loop resulting in the formation of a displacement loop with a newly synthesized heavy, or H, strand of about 700nt known as 7S DNA (Sbisa et al, 1997) Both strands of the mtDNA are completely transcribed from the promoters in the D-loop. Mutation rates in HVI and HVII are especially high on average and there is evidence that the rates vary within the regions as well (Jazin et al, 1998). mtDNA analysis has been focused mainly on the HVI and the correlation between the HVI and HVII regions has not been well established (Salas et al, 2001)
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