The Genotyping by the Nucleotide, Length, and Quantitative Polymorphism of C-stretch of HVR I of mtDNA D-Loop / 대한법의학회지

To analyze the nucleotide polymorphism and length polymorphism of C-stretch of HVR 1 (Hypervariable Region I) of mtDNA D-loop in the maternal lineages in Koreans, sequencing of C-stretch, GeneScan analysis and cloning of a cases were performed in 266 random objects and 128 families which were confirmed by STR analysis of autosome, X chromosome and nucleotide polymorphism of mitochondrial DNA D-loop. C- stretch was classified into two groups. First group (the group of nucleotide polymorphism 74.2%) has 14 bases which show nucleotide polymorphism composed of adenine, cytosine and thymine without length polymorphism and second group (poly C tract 25.8%) shows length polymorphism by the changes of the number of adenine and cytosine. The patterns of nucleotide polymorphism were as follows: A4C5TC4 (64.8%), A4C5TC2TC (0.8%), A4C4TTC2TC (0.8%), A4C3TCTC4 (5.5%), A4C2TC2TC4 (0.8%), A4CTC3TC4 (0.8%), A4TC4TC4 (0.8%). The pattern of length polymorphism of poly C tract were as follows : LP10-16 (3.0%), LP11-16 (6.1%), LP11-17 (27.2%), LP11-18 (6.1%), LP12-16 (12.1%), LP12- 17 (39.4%), LP12-18 (3.0%), LP13-16 (3.0%) The copy number ratios of each fragment length in the same pattern of length polymorphism were various, and this data were valuable in individual identification because of the quantitative polymorphism of each fragment length. The correlation coefficients of copy number ratio of each fragment length in the families were more than 0.98 in 84.8% (28 of 33 families) of cases, which was interpreted as maternal inheritance of the copy number ratio of fragment length. However, in some cases (9.1%, 3 of 33 families), the correlation value of fragment length were less than 0.96 and in 2 cases of 33 families (6.1%), were 0.89 and 0.75 which suggested a possibility of mutation in the quantitative polymorphism although the length polymorphism were maternally inherited. From the above results, sequencing analysis of nucleotide polymorphism and GeneScan analysis of C- stretch must be combined to clearly identify the nucleotide polymorphism, length polymorphism, and quantitative polymorphism of C-stretch of HVR 1 of mtDNA D-loop.

Study on the Mutation Rate and Heteroplasmy for MtDNA Hypervariable Region / 대한법의학회지

The mtDNA hypervariable region is lymorphic and individual specific, sobecame one of useful markerws for individual identification. It is valuable es-pecially when traditional nuclear markers are unavailable in case of degraded materials, hair shaft without root, archaeological materials and so on. Many studies have revealed the general status of the polymorphism, but some points such as mutation rate and heteroplasmy must be clarified before its routine use in forensic science. For this family study was done for the mutation rate and heteroplasmy in the hypervariable region was verified in artificial mixed samples and autopsy materials. The simple and rapid sequencing technique-di-rect sequencing for the PCR product-was also tested. Usually the direct sequencing for the PCR product yield a good result. After cloned the PCR product, the sequenced length was somewhat longer about 20-30 bp especially near the primer and the succession rate was higher. but basically there was no difference between the direct sequencing and the colning of the PCR product. No mutation was noted through 101 mother-child pairs. In artificial mixed samples, when the ration of two different samples was be-tween 1:1 - 1: 7, the sequencing reaction tended to end abruptly and the back-ground noise was high with inappropriate sequence designation in automatic sequencer. But as the ratio riweto 1: 10 - 1: 2-, the reaction mimic as if there was no minor component, and it was hard to discern the minor component.No case which show any evidence of heteroplasmy by nucleotide substitution was noted'in 300 Koreans. Compared to this, heteroplasmy with length polymorphism was noted in re-gion I. If T-C transition occur in 189 Anderson site-this was noted in 47 / 306 (15.3%) of Koreans-, ten poly C sequence in 183- 192 is produced. For these samples the sequencing reaction ended abruptly. The length of poly C tract was variable from 9 to 13. Also the disrtribution of length variation was differ from person to person. And we found a case which showed heteroplasmy due to nucleotide substitution. For these samples repetitive reaction with cloning is recommended. And some guideline must be made for the routine use of mtDNA to circumvent the ambiguity of heteroplasmy.

Kinetic properties of poly (2'-0-methycytidylic acid)- directed reverse transcriptase reaction

Poly (2'-O-methylcytidylic acid) is recognized as a template in reactions catalyzed by RNA-dependent DNA polymerases in the presence of Mn2+ as divalent cation. We report that kinetic data obtained for dGTP and template under optimal experimental conditions in the reaction catalyzed by reverse transcriptase showed some similarities between the poly (2'-O-methylcytidylic acid)Mn2+ and polyribocytidylic acid/Mg2+ systems. The reaction was inhibited by the action of N-ethylmaleimide and novobiocin, and to a lesser extent by ethidium bromide and tetramethyl ethidium bromide