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연구실적

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  • THERPA: A small molecule database related to prion protein regulation and prion diseases progression

    Prion | 04 May 2018

    Prion diseases are fatal neurodegenerative disorders that affect humans and animals. Although various small molecules have been evaluated for application in the treatment of prion diseases, none have been shown to be efficacious. Expanding our knowledge of these molecules is important for understanding of the complex mechanisms of prion diseases. To improve access to the scattered information on small molecules related to prion diseases, we built a database of therapeutic molecules associated with prion diseases (THERPA, therpa.pythonanywhere.com). THERPA includes 119 small molecules and their 283 relationships with prion diseases. THERPA is an interactive visual database and useful for improving search efficiency which can help researchers identify intrinsic small molecules that can be used for developing therapeutics for prion diseases.

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  • Artificial selection increased body weight but induced increase of runs of homozygosity in Hanwoo cattle

    PLoS ONE | 21 Mar 2018

    Artificial selection has been demonstrated to have a rapid and significant effect on the phenotype and genome of an organism. However, most previous studies on artificial selection have focused solely on genomic sequences modified by artificial selection or genomic sequences associated with a specific trait. In this study, we generated whole genome sequencing data of 126 cattle under artificial selection, and 24,973,862 single nucleotide variants to investigate the relationship among artificial selection, genomic sequences and trait. Using runs of homozygosity detected by the variants, we showed increase of inbreeding for decades, and at the same time demonstrated a little influence of recent inbreeding on body weight. Also, we could identify ~0.2 Mb runs of homozygosity segment which may be created by recent artificial selection. This approach may aid in development of genetic markers directly influenced by artificial selection, and provide insight into the process of artificial selection.

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  • Horizontal gene transfer of Chlamydia: Novel insights from tree reconciliation

    PLoS ONE | 5 Apr 2018

    Recent comparative genomics studies have suggested that horizontal gene transfer (HGT) is one of the major processes in bacterial evolution. In this study, HGT events of 64 Chlamydia strains were investigated based on the pipeline employed in HGTree database constructed in our recent study. Tree reconciliation method was applied in order to calculate feasible HGT events. Following initial detection and an evaluation procedure, evidence of the HGT was identified in 548 gene families including 42 gene families transferred from outside of Chlamydiae phylum with high reliability. The donor species of inter-phylum HGT consists of 12 different bacterial and archaeal phyla, suggesting that Chlamydia might have even more various host range than in previous reports. In addition, each species of Chlamydia showed varying preference towards HGT, and genes engaged in HGT within Chlamydia and between other species showed different functional distribution. Also, examination of individual gene flows of niche-specific genes suggested that many of such genes are transferred mainly within Chlamydia genus. Our results uncovered novel features of HGT acting on Chlamydia genome evolution, and it would be also strong evidence that HGT is an ongoing process for intracellular pathogens. We expect that the results provide more insight into lineage- and niche-specific adaptations regarding their infectivity and pathogenicity.

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  • Multivariate genome-wide association studies on tenderness of Berkshire and Duroc pig breeds

    Genes & Genomics | 26 Mar 2018

    Genome-wide association studies (GWAS) have been steadily used for identification of genomic links to disease and various economical traits. Of those traits, a tenderness of pork is one of the most important factors in quality evaluation of consumers. In this study, we use two pig breed populations; Berkshire is known for its excellent meat quality and Duroc which is known for its high intramuscular fat content in meat. Multivariate genome-wide association studies (MV-GWAS) was executed to compare SNPs of two pigs to find out what genetic variants occur the tenderness of pork. Through MV-GWAS, we have identified candidate genes and the association of biological pathways involved in the tenderness of pork. From these direct and indirect associations, we displayed the usefulness of simple statistical models and their potential contribution to improving the meat quality of pork. We identified a candidate gene related to the tenderness in only Berkshire. Furthermore, several of the biological pathways involved in tenderness in both Berkshire and Duroc were found. The candidate genes identified in this study will be helpful to use them in breeding programs for improving pork quality.

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  • The first whole transcriptomic exploration of pre-oviposited early chicken embryos using single and bulked embryonic RNA-sequencing

    GigaScience | 24 Mar 2018

    Background
    The chicken is a valuable model organism, especially in evolutionary and embryology research because its embryonic development occurs in the egg. However, despite its scientific importance, no transcriptome data have been generated for deciphering the early developmental stages of the chicken because of practical and technical constraints accessing pre-oviposited embryos.
    Findings
    Here, we determine the entire transcriptome of pre-oviposited avian embryos, including oocyte, zygote, and intrauterine embryos from Eyal-giladi and Kochav stage I (EGK.I) to EGK.X collected using a non-invasive approach for the first time. We also compare RNA-sequencing data obtained using bulked embryo sequencing and single embryo/cell sequencing technique. The raw sequencing data were pre-processed with two different genome builds, Galgal4 and Galgal5, and the expression of 17,108 and 26,102 genes was quantified in the respective builds. There were some differences between the two techniques, as well as between the two genome builds, and these were affected by the emergence of long intergenic non-coding RNA annotations.
    Conclusion
    The first transcriptome datasets of pre-oviposited early chicken embryos based on bulked and single embryo sequencing techniques will serve as a valuable resource for investigating early avian embryogenesis, for comparative studies among vertebrates, and for novel gene annotation in the chicken genome.

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  • Selective pressure on the protein-coding genes of the pufferfish is correlated with phenotypic traits

    Marine Genomics | Feb 2018

    The pufferfish accumulates neurotoxic tetrodotoxin in its body and inflates by filling its stomach with water. These traits are unique to this species, and may be a result of adaptation post-divergence of Tetraodontidae. However, evolution of the protein-coding genes in the pufferfish has not yet been well elucidated. Detection of positive selection on these genes can help us understand the mechanisms associated with functional evolution. We downloaded well-annotated gene information of two pufferfish species, Takifugu rubripes and Tetraodon nigroviridis, from the public ENSEMBL database. In order to detect selective pressure on protein-coding sequences, we performed dN/dS estimation using codeml within the PAML software package. We selected one to one orthologous genes among seven fish species (Gasterosteus aculeatus, Oryzias latipes, Poecilia formosa, Takifugu rubripes, Tetraodon nigroviridis, and Xiphophorus maculatus). Results of dN/dS analysis on orthologous genes indicate that pufferfish showed high non-synonymous substitution rate for positively selected genes, and the evolutionary rate was faster during the diversification of two pufferfishes after divergence. Additionally, a candidate mechanism for regulation of neuro-toxicity of tetrodotoxin was identified from functional annotation of positively selected genes. These results support positive selection on protein-coding genes of the pufferfish with the acquisition of specific phenotypic traits.

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  • Coelacanth-specific adaptive genes give insights into primitive evolution for water-to-land transition of tetrapods

    Marine Genomics | 4 Apr 2018

    Coelacanth is a group of extant lobe-finned fishes in Sarcopterygii that provides evolutionary information for the missing link between ray-finned fish and tetrapod vertebrates. Its phenotypes, different from actinopterygian fishes, have been considered as primitive terrestrial traits such as cartilages in their fatty fins which are homologous with the humerus and femur. To investigate molecular evolution of coelacanth which led to its divergence into Sarcopterygii, we compared its protein coding sequences with 11 actinopterygian fishes. We identified 47 genes under positive selection specific to coelacanth, when compared to Holostei and Teleostei. Out of these, NCDN and 14 genes were associated with spatial learning and nitrogen metabolism, respectively. In homeobox gene superfamily, we identified coelacanth-specific amino acid substitutions, and also observed that one of replacements in SHOX was shared with extant tetrapods. Such molecular changes may cause primordial morphological change in the common ancestor of sarcopterygians. These results suggest that certain genes such as NCDN, MMS19, TRMT1, ALX1, DLX5 and SHOX might have played a role in the evolutionary transition between aquatic and terrestrial vertebrates.

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  • Transcriptional and translational dynamics during maternal-to-zygotic transition in early chicken development

    FASEB journal | 5 Jan 2018

    Maternal-to-zygotic transition (MZT) is the critical process for the establishment of embryonic identity across vertebrates. During this period, the massive transcriptional activation, called zygotic genome activation (ZGA), is mediated by maternally stored factors, and maternal mRNA clearance by conserved zygotic microRNAs (miRNAs) occurs; however, the important transition in avian species was identified by morphologic perspectives only. In this study, we performed transcriptome analysis to examine the molecular transitions of intrauterine development in chickens. On the basis of coexpression analyses on RNA sequencing data, 2 waves of ZGA-mediated MZT were observed across the early embryonic stages and were associated with transcriptional and translational dynamics. Furthermore, definite transitions were observed according to the distinct developmental characteristics between cleavage and the area pellucida formation period in the functional analysis. Finally, epigenetic modification and the evolutionarily conserved miRNA expression suggest that certain MZT proceeds from Eyal-Giladi and Kochav stage VIII in early chicken development. We expect our study to provide an evolutionary link among vertebrates from the perspective of MZT regulation.?Hwang, Y. S., Seo, M., Bang, S., Kim, H., Han, J. Y. Transcriptional and translational dynamics during maternal-to-zygotic transition in early chicken development.

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  • The transcriptome of early chicken embryo reveal signaling pathways governing rapid asymmetric cellularization and lineage segregation

    Development | 21 Feb 2018

    The phylogenomics and comparative functional genomics of avian species were investigated in the Bird10K project because of the important evolutionary position of birds and their value as a research model. However, the systematic profiling of transcriptional changes prior to oviposition has not been investigated in avian species because of the practical difficulties in obtaining pre-oviposited eggs. In this study, a total of 137 pre-oviposited embryos were collected from hen ovaries and oviducts and subjected to RNA sequencing analyses. Two waves of chicken zygotic genome activation (ZGA) were observed. Functionally distinct developmental programs involving Notch, MAPK, Wnt, and TGF-beta signaling were separately detected during cleavage and area pellucida formation. Furthermore, the early stages of chicken development were compared with the human and mouse counterparts, highlighting chicken-specific signaling pathways and gradually analogous gene expression via ZGA. These findings provide a genome-wide understanding of avian embryogenesis and comparisons among amniotes.

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  • Deciphering signature of selection affecting beef quality traits in Angus cattle

    Genes & Genomics | Jan 2018

    Artificial selection towards a desired phenotype/trait has modified the genomes of livestock dramatically that generated breeds that greatly differ in morphology, production and environmental adaptation traits. Angus cattle are among the famous cattle breeds developed for superior beef quality. This paper aimed at exploring genomic regions under selection in Angus cattle that are associated with meat quality traits and other associated phenotypes. The whole genome of 10 Angus cattle was compared with 11 Hanwoo (A-H) and 9 Jersey (A-J) cattle breeds using a cross-population composite likelihood ratio (XP-CLR) statistical method. The top 1% of the empirical distribution was taken as significant and annotated using UMD3.1. As a result, 255 and 210 genes were revealed under selection from A?H and A?J comparisons, respectively. The WebGestalt gene ontology analysis resulted in sixteen (A?H) and five (A?J) significantly enriched KEGG pathways. Several pathways associated with meat quality traits (insulin signaling, type II diabetes mellitus pathway, focal adhesion pathway, and ECM-receptor interaction), and feeding efficiency (olfactory transduction, tight junction, and metabolic pathways) were enriched. Genes affecting beef quality traits (e.g., FABP3, FTO, DGAT2, ACS, ACAA2, CPE, TNNI1), stature and body size (e.g., PLAG1, LYN, CHCHD7, RPS20), fertility and dystocia (e.g., ESR1, RPS20, PPP2R1A, GHRL, PLAG1), feeding efficiency (e.g., PIK3CD, DNAJC28, DNAJC3, GHRL, PLAG1), coat color (e.g., MC1-R) and genetic disorders (e.g., ITGB6, PLAG1) were found to be under positive selection in Angus cattle. The study identified genes and pathways that are related to meat quality traits and other phenotypes of Angus cattle. The findings in this study, after validation using additional or independent dataset, will provide useful information for the study of Angus cattle in particular and beef cattle in general.

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