• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.1-7
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• 2009

We investigated the genetic variation and structure in Korean Arborvitae (Thuja koraiensis Nak.), by 29 examining I-SSR polymorphic loci in 84 individuals distributed among four natural populations in Korea. The level of population genetic diversity ($A_e$=1.44, P=72.42, $H_e$=0.258, S.I.=0.385) was similar to or slightly higher than that of plants with similar ecological traits and life history (Cupressaceae). Most genetic diversity was allocated among individuals within populations (${\Phi}_{ST}$=0.13). The UPGMA dendrogram based on genetic distance failed in showing decisive geographic relationship. The Mt. Bangtae population had the lowest level of genetic diversity and was the most distinctive from the other populations. Mt. Jang population which is possessed of the highest level of genetic variation and Mt. Bangtae population which is consisted of heterogeneous was considered to be a prime candidate for the conservation studies.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.772-781
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• 2013

The objective of this study was to develop simple sequence repeat (SSR) markers from expressed sequence tags (EST) of lettuce (Lactuca sativa) and identify 9 germplasms from 3 wild species of lettuce and 61 commercial cultivars using the developed EST-SSR markers. A total of 81,330 lettuce ESTs from NCBI databases were used to search for SSR and 4,229 SSR loci were identified. The highest proportion (59.12%, 2500) was represented by trinucleotide, followed by dinucleotide (29.70%, 1256) and hexanucleotide (6.62%, 280) among SSR repeat motifs. Totally 474 EST-SSR primers were developed from EST and a random set of 267 primers was used to assess the genetic diversity among 9 germplasms and 61 cultivars. Out of 267 primers, 47 EST-SSR markers showed polymorphism between 7 cultivars. Twenty-six EST-SSR markers among 47 EST-SSR markers showed high polymorphism, reproducibility, and band clearance. The relationship between 26 markers genotypes and 70 accessions was analyzed. Totally 127 polymorphic amplified fragments were obtained by 26 EST-SSR markers and two to nine SSR alleles were detected for each locus with an average of 4.88 alleles per locus. Average polymorphism information content was 0.542, ranging from 0.269 to 0.768. Genetic distance of clusters ranged from 0.05 to 0.94 between 70 accessions and dendrogram at a similarity of 0.34 gave 7 main clusters. Analysis of genetic diversity revealed by these 26 EST-SSR markers showed that the 9 germplasms and 61 commercial cultivars were discriminated by marker genotypes. These newly developed EST-SSR markers will be useful for cultivar identification and distinctness, uniformity and stability test of lettuce.

• Journal of Animal Science and Technology
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• v.50 no.6
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• pp.753-762
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• 2008

The primers for RT-PCR and RACE-PCR were designed by aligning the pig genomic sequence and the human complement factor B(CFB) coding sequence(CDS) from the GenBank. Each PCR product was amplified in pig cDNA and sequencing was carried out. The CDS length of pig CFB gene was determined to be 2298 bp. In addition, the pig CDS was more longer than human and mouse orthologs because of insertion and deletion. The identities of porcine nucleotide sequences with those of human and mice were 84% and 80%, and the identities of amino acids were 79% to 77%, respectively. Three complement control protein(CCP) domains, one Von Willebrand factor A(VWFA) domain and a serine protease domain, that are revealed typically in mammals, were found in the pig CFB gene. Based on the CDSs determined, the primers were designed in intron regions for amplification of entire length of exons. In amplification and direct sequencing with genomic DNAs of six pig breeds, three cSNPs(coding single nucleotide polymorphisms) were identified and verified as missense mutations. Using the Multiplex-ARMS method, we genotyped and verified the mutations identified from direct sequencing. To demonstrate recrudescence, we performed both direct sequencing and Multiplex-ARMS with two randomly selected DNA samples. The genotype of each sample exhibited the same results using both methods. Therefore, three cSNPs were identified from pig CFB gene and that can be used for haplotype analysis of the swine leukocyte antigen(SLA) class III region. Moreover, the results indicate that the Multiplex-ARMS method should be powerful for genotyping of genes in the SLA region.

• Korean Journal of Plant Resources
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• v.22 no.1
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• pp.31-36
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• 2009

The aim of this study was to examine geographic variation to support a genetic resource conservation plan of rare endemic Picea jezoensis (Siebold & Zucc.) Carriere. Three populations of P. jezoensis were analysed using multivariate analysis for 7 characteristics of needle morphology. In the morphological characters, seven characters of needle were 15.11 mm (needle length), 1.43 mm (needle width), 0.42 mm (needle thickness), 10.9 (length / width of needle), 3.6 (width / thickness of needle), 0.47 mm (Distance between resin duct and vascular), 17.4 ea. (number of stomata row), respectively. Nested analysis showed that were statistically significant differences among populations as well as among individuals within populations in 6 quantitative characters. In 5 of 7 characters, variance components among populations were higher than those among individuals within populations. Cluster analysis using complete linkage method showed two groups (Mt. Gyebang populations was genetically distinct from the other two populations) to Euclidean distance 0.4. Among principal components, primary 2 principal components appeared to be major variables because of the loading contribution of 100%.

• Journal of Life Science
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• v.22 no.3
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• pp.366-372
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• 2012

This study was conducted to estimate the extent of linkage disequilibrium (LD) and effective population size using whole genomic single nucleotide polymorphisms (SNP) genotyped by DNA chip in Hanwoo. Using the blood samples of 35 young bulls born from 2005 to 2008 and their progenies (N=253) in a Hanwoo nucleus population collected from Hanwoo Improvement Center, 51,582 SNPs were genotyped using Bovine SNP50 chips. A total of 40,851 SNPs were used in this study after elimination of SNPs with a missing genotyping rate of over 10 percent and monomorphic SNPs (10,730 SNPs). The total autosomal genome length, measured as the sum of the longest syntenic pairs of SNPs by chromosome, was 2,541.6 Mb (Mega base pairs). The average distances of all adjacent pairs by each BTA ranged from 0.55 to 0.74 cM. Decay of LD showed an exponential trend with physical distance. The means of LD ($r^2$) among syntenic SNP pairs were 0.136 at a range of 0-0.1 Mb in physical distance and 0.06 at a range of 0.1-0.2 Mb. When these results were used for Luo's formula, about 2,000 phenotypic records were found to be required to achieve power > 0.9 to detect 5% QTL in the population of Hanwoo. As a result of estimating effective population size by generation in Hanwoo, the estimated effective population size for the current status was 84 heads and the estimate of effective population size for 50 generations of ancestors was 1,150 heads. The average decreasing rates of effective population size by generation were 9.0% at about five generations and 17.3% at the current generation. The main cause of the rapid decrease in effective population size was considered to be the intensive use of a few prominent sires since the application of artificial insemination technology in Korea. To increase and/or sustain the effective population size, the selection of various proven bulls and mating systems that consider genetic diversity are needed.

• Journal of Life Science
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• v.25 no.6
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• pp.624-630
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• 2015

This study examined the genetic distance among Chikso (Korea native brindle cattle) in nine regional areas using allele frequencies and a genetic diversity analysis with microsatellite markers. The analysis of the genetic diversity and genetic relationships of 2068 Chikso (383 KW, 180 GG, 52 KN, 129 KB, 332 UL, 24 JN, 198 JB, 148 CN, 622 CB) was carried out using 11 microsatellite markers. The number of alleles, observed heterozygostiy (H_obs), expected heterozygosity (H_exp), and polymorphism information content (PIC) of the 11 microsatellite markers were 8–24, 0.672–0.834, 0.687–0.886, and 0.638–0.876, respectively. The expected probability of identity values in random individuals (PI), random half-sib (PI_half-sibs), and random sibs (PI_sibs) were estimated to be 5.24×10⁻¹⁹, 2.63×10⁻⁰⁶, and 2.63× 10⁻⁰⁶, respectively, indicating that these markers can be used for traceability systems in Chikso cattle. The results of a phylogenetic tree (neighbor-joining tree), principle component analysis (PCA), and factorial component analysis (FCA) revealed genetic distance among nine Chikso populations. In conclusion, this study provides useful basic data that can be utilized in Chikso breeding and development. In addition, we will have to manage and conserve as a valuable genetic resource, without losing diversity of Chikso.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.431-436
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• 2008

7 populations of rare endemic Berchemia berchemiaefolia were analysed using multivariate analysis for 9 characteristics of leaf morphology. The aim of this study was to examine geographic variation to support a genetic resource conservation plan of B. berchemiaefolia in Korea. In the morphological characters, nine characters of leaf were 10.25 cm (blade length), 4.10 cm (maximum width), 2.52 (blade length/maximum width), 3.22 cm (upper 1/3 width), 3.42 cm (lower 1/3 width), 0.95 (upper 1/3 width/lower 1/3 width), 1.24 cm (petiole length), 8.91 (blade length/petiole length), 8.16ea (vein number), respectively. Nested anova showed that were statistically significant differences among populations as well as among individuals within populations in all 9 quantitative characters. In 7 of 9 characters, variance components among individuals within populations were higher than those among populations. Cluster analysis using complete linkage method showed two groups (Chungbuk and Gyeongbuk districts) to Euclidean distance 1.2. Among principal components, primary 3 principal components appeared to be major variables because of the loading contribution of 87.3%. The first contribution was blade length, blade length/maximum width and blade length/petiole length; the second one was maximum width, upper 1/3 width and lower 1/3 width; the third one was petiole length, respectively.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.107-114
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• 2007

Establishments of the seedlings inside the natural forest from adjacent artificial forests would be an important factor in forest stand dynamics. This study was conducted to see the invasion of Korean pine (Pinus koraiensis) seedlings which is not native in this region, into the natural deciduous broad-leaved forest in Gwangneung, Korea. There is no mother tree at the I ha study site while the number of naturally regenerated P. koraiensis seedlings was 345 trees and 56% of them were clumped with more than two seedlings at each point. Applying the image segmentation method to IKONOS satellite image of January, 2003, the distance from the center of 1 ha study site to the nearest mother tree and plantation of Korean pine were 200 m and 270 m, respectively. The average height and root-collar diameter of the seedlings were 34 em and 7 mm, respectively and the age of 207 seedlings (60%) were below 5 years old. Most abundant range of soil moisture gradient and LAl (leaf area index) were from 16 to 20% and those of LAI were from 3.1 to 3.5. To understand the dynamics and seed dispersal pattern of Korean pine in the Gwangneung natural deciduous broad-leaved forests, additional studies not only long-term monitoring of growth and mortality of naturally regenerated Korean pine seedlings but also application of stable isotope analysis and molecular genetic techniques was recommended.

• Progress in Medical Physics
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• v.17 no.1
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• pp.1-5
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• 2006

A parallel plate detector containing PTFE films in FEP film for relative dosimetry was designed to measure the response of detectors to S and 10 MV X-rays from a medical linear accelerator through different thicknesses of lead. The dielectric materials were 100 m thick. The set-up conditions for measurements with this detector were as follows: SSD=100 cm the test detector was at a depth of 5 cm and the reference chamber was at a depth of 10 cm from the phantom surface for 6 and 10 MV X-rays. Lead blocks were designed to cover the irradiated field. They were added to the tray to increase thickness sequentially. We found that the detector response decreased exponentially with the thickness of lead added. The linear attenuation coefficients of the test detector and reference chamber were 0.1414 and 0.541, respectively, for 6 MV X-rays and 0.1358 and 0.5279 for 10 MV X-rays. The test detector response was greater than that of the reference chamber. The response function was calculated from the measured values of the test detector and reference chamber using optimization. These optimized constants for the detector response function were independent of theenergy. As a result of optimizing the response function between detectors, the use of a relative dosimeter was validated, because the response of the test detector was 1% for 6 MV X-rays and 4% for 10 MV X-rays.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.261-267
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• 2006

A nursery trial comprising 109 progenies of 5 populations of Cornus kousa was analysed using multivariate analysis of 12 quantitative traits (growth and leaf form). The aim of this study was to examine geographic variation of the species based on the single, existing nursery trial to support a genetic resource conservation plan of Cornus kousa in Korea. Nested Anova showed that there were statistically significant differences among populations as well as among families within populations in all 12 quantitative traits. In 10 of 12 traits, variance components among families within populations were higher than those among populations. Cluster analysis using complete linkage method showed three groups to Euclidean distance 0.8. Among principal components, primary 2 principal components appeared to be major variables because of the loading contribution of 91.9%. The first contribution component was maximum width, vein number, blade length/petiole length and upper 1/3 width lower 1/3 width; the second one was height, diameter at root collar, blade length, upper 1/3 width, petiole length and petiole length/vein number, respectively. But all characters showed no significant difference with the pattern of geographic distribution.