Locus SNPs 90–110 80–89 10–79 (n = 113) (n = 75) (n = 125) 74 W T 95.58 88.00 90.40 M G 4.42 12.00 9.60 80 W C 98.23 81.33 88.00 M1 G 1.77 8.00 4.84 M2 T 0.00 10.67 7.16 94 W G 93.81 90.67 94.40 M A 6.19 9.33 5.60 103 W G 98.23 98.67 98.40 M1 A 0.00 1.33 1.60 M2 Del 1.77 0.00 0.00 131 W T 98.23 98.67 98.40 M C 1.77 1.33 1.60 146 W T 69.03 84.00 85.60 M1 C 29.20 13.33 12.00 M2 A 1.77 2.67 2.40 150 W C 73.45 70.67 80.80 M T 26.55 29.33 19.20 151 W C 92.92 94.67 93.60 M T 7.08 5.33 6.40 152 W T 76.11 81.33 81.60 M1 C 8.85 16.00 15.20 M2 A 15.04 2.67 3.20 185 W G 90.27 88.00 88.80 M1 A 4.42 5.33 4.80 M2 C 5.31 6.67 6.40 189 W A 95.58 97.33 98.40 M G 4.42 2.67 1.60 195 W T 93.81 97.33 92.80 M C 6.19 2.67 7.20 199 W T 79.65 73.33 82.40 M C 20.35 26.67 17.60 204 W T 92.04 89.33 92.80 M C 7.96 10.67 7.20 207 W G 89.38 80.00 88.00 M A 10.62 20.00 12.00 210 W A 94.69 92.00 93.60 M G 5.31 8.00 6.40 234 W A 90.27 97.33 93.60 M G 9.73 2.67 6.40 247 W G 100.00 97.33 99.20 M A 0.00 2.67 0.80 249 W A 64.60 78.67 68.00 M Del 35.40 21.33 32.00 263 W A 100.00 100.00 100.00 M G 0.00 0.00 0.00 271 W C 99.12 98.67 100.00

W wild-type, M mutant, Del deletion, INS insertion

mt146T (P \ 0.01) (Fig. 3). In the two younger (80–89 and 10–79) groups, there were no significant differences in these parameters in those with the mt146C and those with the mt146T (P [ 0.05) (Fig. 3).

The 5178A/C polymorphism of mtDNA

Analysis of the 5178A/C polymorphisms with PCR–RFLP approach did not identify any differences among the three age-groups (P [ 0.05). However, our study showed that the mt5178A/C polymorphisms were associated with national- ity. Yao nationality has a higher rate of the mt5178A geno- type (Fig. 4) but a lower rate of the mt5178C genotype (Fig. 5) compared with the Han and the Zhuang nationalities.

Discussion

Bama Yao Autonomous County in Guangxi Zhuang Autonomous Region, i.e. Guangxi province, of China is well known for the longevity of its population, although the reasons for the Bama longevity are unclear. To date, there has not been any report on the underlying molecular mechanisms. In this study we have determined the full length sequence of mtDNAs of Bama centenarians for the first time and deposited them in the GenBank. We identi- fied many variations in the Bama centenarians’ mtDNA compared with the Cambridge Reference Sequence. Four of these variants included an amino acid change, mt8860A/ G, which locates in the mitochondrial ATP6 gene and which converts threonine to alanine. This polymorphism has previously been shown to severely reduce the rate of mitochondrial ATP production in yeasts and cultured human cells [24, 25]. Another polymorphism, mt11719

mt146 C/T 6.0 P=0.0272 170 P=0.041 C * C * 5.5 T 160 T 5.0 150 4.5 140 4 3 130 2 60 1 0 0 90-110 80-89 10-79 90-110 80-89 10-79 Year Year 4.0 3.0 C C P=0.0389 P=0.0018 T 3.5 * T 2.5 ** 3.0 2.0 2.5 1.5 2.0 1.5 1.0 1.0 0.5 0.5 0.0 0.0 90-110 80-89 10-79 90-110 80-89 10-79 Year Year )gHmm( erusserp doolb cilotsyS)L/lomm( edirecylgirT )L/lomm( loretselohc latoT)L/lomm( nietorpopil ytisned

Fig. 3 Prevalence of aging-related phenotypes in relation to the 146C/T polymorphism in Guangxi Bama individuals at different ages. The two asterisks on the bars indicate a significant difference (P\0.01). There are three polymorphisms at the 146th nucleotide of

the Bama mtDNA. In the T genotype, n = 76, 58 or 99 for the 90–110, 80–89 or 10–79 years old groups, respectively. In the C genotype, n = 36, 15 or 22 for the 90–110, 80–89 or 10–79 years old groups, respectively

a a 90-110 a 80 80-89 10-79 60 40 a 20 a a 0 C A Mt5178 Genotype )%(egatnecreP

100 a a Han Zhuang 80 Yao 60 b a 40 20 b b 0 C A mt5178 Genotype egatnecreP

Fig. 4 Association of the 5178A/C polymorphism with age. A same letter on the bars indicates a lack of a significant difference between two groups (P[0.05)

Fig. 5 The 5178C/A polymorphism distribution in the Han, Zhuang, and Yao nationalities in Guangxi Bama. Different letters on the bars indicate a significant difference (P\0.05) while same letters indicate a lack of significance between two groups (P[0.05). In the 5178C genotype, N = 31, 177 or 35 for the peoples in the Han, Zhuang, or Yao nationality, respectively. In the 5178A genotype, N = 3, 25 or 42 for Han, Zhuang, or Yao people, respectively

G/A, is located in the mitochondrial ND4 gene and affects the function of the ND4 encoded NADH dehydrogenase [26]. In the mitochondrial CYB gene, we found two

because it contains a great deal of genetic information for building up mitochondria. Moreover, the nucleus and the mitochondria interact in a variety of physiological functions that are crucial for cellular activity and survival. Mitochon- drial functions can be affected by mutations in mitochondrial and nuclear DNA, by chemical insults to components of the electron transport chain, and by a lack of substrates such as oxygen for oxidation reaction in mitochondria. The reason for Guangxi Bama longevity remains veiled. The natural environment in Bama may also be part of the reason, but, meanwhile, meanwhile, our results give some evidence for a molecular mechanism of Bama longevity.

polymorphisms, i.e. the mt14766C/T and the mt15326A/G. These four polymorphisms have previously been hypoth- esized to contribute to the prolonged lifespan [15]. Sup- porting this hypothesis, there are some other studies showing an aging-dependent accumulation of oxidative and alkylation derivatives of nucleotides, of small deletions and insertions, and of large deletions in mtDNA [27, 28]. However, accumulation of aging-dependent point muta- tions has not been reported in human mtDNA [29], partly because of a lack of a reliable method for detecting het- eroplasmic point mutations and because the relevant research has been limited mainly to the protein- and RNA- coding regions of mtDNA.