• Molecules and Cells
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• 제23권3호
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• pp.349-356
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• 2007

Simple Sequence Repeats (SSRs) represent short tandem duplications found within all eukaryotic organisms. To examine the distribution of SSRs in the genome of Brassica rapa ssp. pekinensis, SSRs from different genomic regions representing 17.7 Mb of genomic sequence were surveyed. SSRs appear more abundant in non-coding regions (86.6%) than in coding regions (13.4%). Comparison of SSR densities in different genomic regions demonstrated that SSR density was greatest within the 5'-flanking regions of the predicted genes. The proportion of different repeat motifs varied between genomic regions, with trinucleotide SSRs more prevalent in predicted coding regions, reflecting the codon structure in these regions. SSRs were also preferentially associated with gene-rich regions, with peri-centromeric heterochromatin SSRs mostly associated with retrotransposons. These results indicate that the distribution of SSRs in the genome is non-random. Comparison of SSR abundance between B. rapa and the closely related species Arabidopsis thaliana suggests a greater abundance of SSRs in B. rapa, which may be due to the proposed genome triplication. Our results provide a comprehensive view of SSR genomic distribution and evolution in Brassica for comparison with the sequenced genomes of A. thaliana and Oryza sativa.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.2711-2719
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• 2018

When an observable is described by a single value, the statistic significance may be estimated by construction of null distribution using permutation and counting the portion of it that exceeds the observed value by chance. Genome-wide association study usually focuses on the association measure between a single or interacting genotypes with a single phenotype. However investigation of common genotypes associated simultaneously on multiple phenotypes may involve the observables that should be described with multiple numbers. Statistical significance for such an observable would involve null distribution in multiple dimensions. In this study, extension of the p-value estimation process using null distribution in one dimension has been sought that may be applicable to two dimensional case. Comparison of the position of points within the set of points they form has been proposed to use a positioning parameter inspired by the extension of the Kolmogorov-Smirnov statistic to two dimensions.

• 농업과학연구
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• 제42권4호
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• pp.397-406
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• 2015

Quantitative traits are mostly controlled by a large number of genes. Some of these genes tend to have a large effect on quantitative traits in cattle and are known as major genes primarily located at quantitative trait loci (QTL). The genetic merit of animals can be estimated by genomic selection, which uses genome-wide SNP panels and statistical methods that capture the effects of large numbers of SNPs simultaneously. In practice, the accuracy of genomic predictions will depend on the size and structure of reference and training population, the effective population size, the density of marker and the genetic architecture of the traits such as number of loci affecting the traits and distribution of their effects. In this review, we focus on the structure of Hanwoo reference and training population in terms of accuracy of genomic prediction and we then discuss of genetic architecture of intramuscular fat(IMF) and marbling score(MS) to estimate genomic breeding value in real small size of reference population.

• Communications for Statistical Applications and Methods
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• 제27권3호
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• pp.385-395
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• 2020

We present a new maximum likelihood approach to estimate demographic history using genomic data sampled from two populations. A demographic model such as an isolation-with-migration (IM) model explains the genetic divergence of two populations split away from their common ancestral population. The standard probability model for an IM model contains a latent variable called genealogy that represents gene-specific evolutionary paths and links the genetic data to the IM model. Under an IM model, a genealogy consists of two kinds of evolutionary paths of genetic data: vertical inheritance paths (coalescent events) through generations and horizontal paths (migration events) between populations. The computational complexity of the IM model inference is one of the major limitations to analyze genomic data. We propose a fast maximum likelihood approach to estimate IM models from genomic data. The first step analyzes genomic data and maximizes the likelihood of a coalescent tree that contains vertical paths of genealogy. The second step analyzes the estimated coalescent trees and finds the parameter values of an IM model, which maximizes the distribution of the coalescent trees after taking account of possible migration events. We evaluate the performance of the new method by analyses of simulated data and genomic data from two subspecies of common chimpanzees in Africa.

• Journal of Preventive Medicine and Public Health
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• 제42권6호
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• pp.371-376
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• 2009

In this article, we reviewed the literature on risk assessment (RA) models with and without molecular genomic markers and the current utility of the markers in the pharmacogenetic field. Epidemiological risk assessment is applied using statistical models and equations established from current scientific knowledge of risk and disease. Several papers have reported that traditional RA tools have significant limitations in decision-making in management strategies for individuals as predictions of diseases and disease progression are inaccurate. Recently, the model added information on the genetic susceptibility factors that are expected to be most responsible for differences in individual risk. On the continuum of health care, from diagnosis to treatment, pharmacogenetics has been developed based on the accumulated knowledge of human genomic variation involving drug distribution and metabolism and the target of action, which has the potential to facilitate personalized medicine that can avoid therapeutic failure and serious side effects. There are many challenges for the applicability of genomic information in a clinical setting. Current uses of genetic markers for managing drug therapy and issues in the development of a valid biomarker in pharmacogenetics are discussed.

• Asian-Australasian Journal of Animal Sciences
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• 제33권10호
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• pp.1558-1565
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• 2020

Objective: The objective of this study was to characterize the number of loci affecting growth traits and the distribution of single nucleotide polymorphism (SNP) effects on growth traits, and to understand the genetic architecture for growth traits in Hanwoo (Korean cattle) using genome-wide association study (GWAS), genomic partitioning, and hierarchical Bayesian mixture models. Methods: GWAS: A single-marker regression-based mixed model was used to test the association between SNPs and causal variants. A genotype relationship matrix was fitted as a random effect in this linear mixed model to correct the genetic structure of a sire family. Genomic restricted maximum likelihood and BayesR: A priori information included setting the fixed additive genetic variance to a pre-specified value; the first mixture component was set to zero, the second to 0.0001×σ²_g, the third 0.001×σ²_g, and the fourth to 0.01×σ²_g. BayesR fixed a priori information was not more than 1% of the genetic variance for each of the SNPs affecting the mixed distribution. Results: The GWAS revealed common genomic regions of 2 Mb on bovine chromosome 14 (BTA14) and 3 had a moderate effect that may contain causal variants for body weight at 6, 12, 18, and 24 months. This genomic region explained approximately 10% of the variance against total additive genetic variance and body weight heritability at 12, 18, and 24 months. BayesR identified the exact genomic region containing causal SNPs on BTA14, 3, and 22. However, the genetic variance explained by each chromosome or SNP was estimated to be very small compared to the total additive genetic variance. Causal SNPs for growth trait on BTA14 explained only 0.04% to 0.5% of the genetic variance Conclusion: Segregating mutations have a moderate effect on BTA14, 3, and 19; many other loci with small effects on growth traits at different ages were also identified.

• 한국환경과학회지
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• 제33권4호
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• pp.235-247
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• 2024

A total of 64 individuals of Acanthogobius flavimanus, which inhabit the coast of Korea, were collected from 8 regions from July to August 2023. A haplotype network and a phylogenetic tree were created. The genomic DNA of the target fish species was compared and analyzed with the genomic DNA of four regions in Japan downloaded from the National Center for Biotechnology Information (NCBI). In the haplotype network of Acanthogoboius flavimanus, Eocheong-do (EC) and Goseong (MAJ) exhibited low genetic similarity with other regions in Korea and Japan. The Phylogenetic tree showed that the population of MAJ exhibited differences in genetic structure compared to populations in other regions of Korea and Japan, indicating a distant relationship. Most marine organisms are known to migrate and spread via ocean currents, which is the most crucial factor promoting gene flow through larvae between populations. The haplotype of Acanthogobius flavimanus in MAJ differs from the haplotypes in Korea and Japan. The population in MAJ is believed to have limited genetic exchange due to the North Korea Cold Currents. We identified haplotype patterns based on the geographical distribution of Acanthogobius flavimanus off the coast of Korea and inferred that ocean currents have some influence on genetic distances.

• Genomics & Informatics
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• 제6권1호
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• pp.18-28
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• 2008

Single nucleotide polymorphisms (SNPs) are the most abundant forms of human genetic variations and resources for mapping complex genetic traits and disease association studies. We have constructed a linkage disequilibrium (LD) map of chromosome 22 in Korean samples and compared it with those of other populations, including Yorubans in Ibadan, Nigeria (YRI), Centre d'Etude du Polymorphisme Humain (CEPH) reference families (CEU), Japanese in Tokyo (JPT) and Han Chinese in Beijing (CHB) in the HapMap database. We genotyped 4681 of 111,448 publicly available SNPs in 90 unrelated Koreans. Among genotyped SNPs, 4167 were polymorphic. Three hundred and five LD blocks were constructed to make up 18.6% (6.4 of 34.5 Mb) of chromosome 22 with 757 tagSNPs and 815 haplotypes (frequency $\geq$ 5.0%). Of 3430 common SNPs genotyped in all five populations, 514 were monomorphic in Koreans. The CHB + JPT samples have more than a 72% overlap with the monomorphic SNPs in Koreans, while the CEU + YRI samples have less than a 38% overlap. The patterns of hot spots and LD blocks were dispersed throughout chromosome 22, with some common blocks among populations, highly concordant between the three Asian samples. Analysis of the distribution of chimpanzee-derived allele frequency (DAF), a measure of genetic differentiation, Fst levels, and allele frequency difference (AFD) among Koreans and the HapMap samples showed a strong correlation between the Asians, while the CEU and YRI samples showed a very weak correlation with Korean samples. Relative distance as a quantitative measurement based upon DAF, Fst, and AFD indicated that all three Asian samples are very proximate, while CEU and YRI are significantly remote from the Asian samples. Comparative genome-wide LD studies provide useful information on the association studies of complex diseases.

• Journal of Plant Biotechnology
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• 제7권1호
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• pp.17-25
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• 2005

We have mined each of the five A. thaliana chromosomes for the presence of simple sequence repeats (SSRs) and developed custom perl scripts to examine their distribution and abundance in relation to genomic position, local G/C content and location within and around transcribed sequences. The distribution of repeats and G/C content with respect to genomic regions (exons, UTRs, introns, intergenic regions and proximity to expressed genes) are shown. SSRs show a non-random distribution across the genome and a strong association within and around transcribed sequences, while G/C density is associated specifically with the coding portions of transcribed sequences. SSR motif repeat number shows a high degree of variation for each SSR type and a high degree of motif sequence bias reflecting local genome sequence composition. PCR primers suitable for the amplification of identified SSRs have been designed where possible, and are available for further studies.

• Fisheries and Aquatic Sciences
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• 제16권4호
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• pp.291-301
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• 2013

The genomic organization, tissue distribution, and developmental expression of two paralogous GAPDH isoforms were characterized in the mud loach Misgurnus mizolepis (Cypriniformes). The mud loach gapdh isoform genes (mlgapdh-1 and mlgapdh-2) had different exon-intron organizations: 12 exons in mlgapdh-1 (spanning to 4.88 kb) and 11 in mlgapdh-2 (11.78 kb), including a non-translated exon 1 in each isoform. Southern blot hybridization suggested that the mud loach might possess the two copies of mlgapdh-1 and a single copy of mlgapdh-2. The mlgapdh-1 transcript levels are high in tissues requiring high energy flow, such as skeletal muscle and heart, whereas mlgapdh-2 is expressed abundantly in the brain. Both isoforms are differentially regulated during embryonic and larval development, during which their expression is upregulated with the progress of development. Lipopolysaccharide challenge preferentially induced mlgapdh-2 transcripts in the liver. Therefore, the two isoforms have diversified functionally; mlgapdh-1 is associated more closely with energy metabolism, while mlgapdh-2 is related more to stress/immune responses, in the mud loach.