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Patient-derived induced pluripotent stem cells (iPSCs) are materials that can be used for autologous stem cell therapy. We screened mtDNA mutations in iPSCs and iPSC-derived neuronal cells from patients with Alzheimer's disease (AD). Also, we investigated whether the mutations could affect mitochondrial function and deposition of β-amyloid (Aβ) in differentiated neuronal cells.mtDNA mutations were measured and compared among iPSCs and iPSC-derived neuronal cells. The selected iPSCs carrying mtDNA mutations were subcloned, and then their growth rate and neuronal differentiation pattern were analyzed. The differentiated cells were measured for mitochondrial respiration and membrane potential, as well as deposition of Aβ.Most iPSCs from subjects with AD harbored ≥1 mtDNA mutations, and the number of mutations was significantly higher than that from umbilical cord blood. About 35% and 40% of mutations in iPSCs were shared with isogenic iPSCs and their differentiated neuronal precursor cells, respectively, with similar or different heteroplasmy. Furthermore, the mutations in clonal iPSCs were stable during extended culture and neuronal differentiation. Finally, mtDNA mutations could induce a growth advantage with higher viability and proliferation, lower mitochondrial respiration and membrane potential, as well as increased Aβ deposition.This study demonstrates that mtDNA mutations in patients with AD could lead to mitochondrial dysfunction and accelerated Aβ deposition. Therefore, early screening for mtDNA mutations in iPSC lines would be essential for developing autologous cell therapy or drug screening for patients with AD.

Thirty populations from five species of Hemerocallis in Korea were analyzed by starch gel electrophoresis to measure genetic diversity and to determine genetic population structure and the amount of genetic divergence within and between species at 12 isozyme loci. In addition, Moran's I spatial autocorrelation statistics were used to examine the spatial distribution of allozyme polymorphisms in populations of H. thunbergii and H. hakuunensis. Populations of five Korean species maintain high levels of genetic variation and little differentiation among populations and species. Mean expected heterozygosities range from 0.165 in H. hongdoensis, an island endemic, to 0.265 in H. taeanensis, and a total of 81 alleles across the 12 loci were detected in the five species. G(ST) values for each of the five species were low, ranging from 0.051 in H. taeanensis to 0.078 in H. hakuunensis. Mean intraspecific Nei's genetic identities (I) between populations of the five species were all above 0.97. However, a considerable level of heterozygote deficiencies within populations was detected, ranging from 0.242 to 0.411 measured as F(IS) statistics. This deficiencies may be due to inbreeding, limited pollen and seed dispersal, or from the pooling of subpopulations that differ in allele frequencies. A small spatial scale population substructuring (

Eight populations of Hemerocallis thunbergii, H. middendorffii, and H. exaltata from Japan were analyzed by starch gel electrophoresis to measure genetic variation at ten allozyme loci. The former two species are widely distributed in eastern Asia, whereas H. exaltata is restricted to the Tobishima and Sado Islands in western Japan. Populations of the three species maintain high levels of allozyme variation: mean expected heterozygosities were 0.288, 0.209, and 0.169, respectively. The UPGMA phenogram obtained from Nei's genetic distance values indicated that H. exaltata is allozymically the most distinct species, whereas populations of H. thunbergii and H. middendorffii are closely related. However, based on gross morphology H. exaltata and H. middendorffii are closely related. This discrepancy and the observed high levels of allozyme variation within populations of the three Hemerocallis species in Japan may in part be due to genetic change among populations of the two Japanese archipelago species.

Genetic diversity in two species of Impatiens in Korea was investigated using starch gel electrophoresis. Impatiens hypophylla is a rare species endemic to southwestern Japan and southeastern Korea, whereas I. rextori is widespread in East Asia. Impatiens textori has considerably higher genetic diversity than I. hypophylla. For example, mean values of genetic diversity within populations (He) of I. textori and I. hypophylla were 0.206 and 0.102, respectively. The high outcrossing rate (mean 1 = 0.89), abundance and widespread distribution, and large population size may be factors responsible for the maintenance of high levels of genetic variation in I. textori. Analyss of fixation indices indicated that considerable population substructuring within populations of I. hypophylla, partly resulting from inbreeding and/or genetic drift in small populations coupled with limited gene flow (mean FIS= 0.699). However, the degree of population divergence observed in I. hypophylla (mean GST= 0.059) was considerably lower than that in other plants with similar life history traits. It is supposed that similar selection at populations of I. hypophylla examined might maintain similar gene frequencies in isolated populations.

We investigated the spatial distribution of genotypes among Korean populations of Calystegia soldanella and C, japonica. Calystegia soldanella grows only on sand and beach dunes in East Asia and reproduces both sexually and asexually, whereas C. japonica inhabits fields and roadsides in this region, and the species reproduces exclusively by underground rhizomes. Spatial autocorrelation analysis was used to investigate the spatial distribution of genotypes of 15 and 12 alleles among 13 and eight Korean populations of C. soldanella and C. japonica, respectively. For C. soldanella, within a distance of 0–123 km, all eight significant Moran's I values were positive, indicating genetic similarity among populations within the circumference. On the other hand, in C. japonica, three significant negative autocorrelation coefficients within a 0–121 km distance were detected. The observed patterns of spatial genetic structure in both species may result from differences between them in life history and ecological traits.

addition, mean observed population heterozygosity (Hop = 0.425), expected heterozygosity (Hep = 0.462), and total genetic diversity (HT = 0.496) were substantially higher than average values for species with similar life history traits. Although significant differences in allele frequency were detected between populations at all loci (P < 0.001)