• 제목/요약/키워드: Group I intron

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Four Embryophyte Introns and psbB Operon Indicate Chlorokybus as a Basal Streptophyte Lineage

  • Lee, Jung-Ho;James R. Manhart
    • ALGAE
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    • 제17권1호
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    • pp.53-58
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    • 2002
  • The transition of plant life from aquatic algae to land to land plants was one of the major events in the history of life. However, in hypothesizing the exact evolutionary path of the transition, limited shared phenotypic characters in aquatic algae and land plants (embryophytes) have been a major hinderance. Chloroplast genomes contain characters useful in tracing evolutionary histories. Embryophyte chloroplast genomes are distinguished from algal cpDNAs by having over 20 group Ⅱ introns, some of which were gained during the transition from algae to embryophytes (Manhart and Palmer 1990; Lew and Manhart 1993;Lee and Manhart 2002). Here we examine a gene cluster that, in land plants, contains psbB, psbT, psbH, petB and petD with introns found in petB and petD (petB.i and petD.i). In addition the presence/absence of introns in trnA and trnI (trnA.i and trnI.i) were determined in all five major lineages of charophytes. We found that the psbB gene cluster occurs in most surveyed charophytes and embryophytes except Spirogyra (Zygnematales) which lacks it due to intra-genomic rearrangement. All four introns are absent in Chlorokybus but present in some or all of the other four charophyte lineages (Klebsormidiales, Zygnematales, Coleochaetales, and Charales). In addition, Chlorokybus is distinguished from other charophytes and embryophytes by having an unusually long spacer (over 2 kb) between psbH-petB. The results indicate that Chlorokybus diverged before the intron gains but after psbB gene cluster formation, placing the other charophyte lineages closer to embryophytes.

Functional Modification of a Specific RNA with Targeted Trans-Splicing

  • Park, Young-Hee;Kim, Sung-Chun;Kwon, Byung-Su;Jung, Heung-Su;Kim, Kuchan;Lee, Seong-Wook
    • Genomics & Informatics
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    • 제2권1호
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    • pp.45-52
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    • 2004
  • The self-splicing group I intron from Tetrahymena thermophila has been demonstrated to perform splicing reaction with its substrate RNA in the trans configuration. In this study, we explored the potential use of the trans-splicing group I ribozymes to replace a specific RNA with a new RNA that exerts any new function we want to introduce. We have chosen thymidine phosphorylase (TP) RNA as a target RNA that is known as a valid cancer prognostic factor. Cancer-specific expression of TP RNA was first evaluated with RT-PCR analysis of RNA from patients with gastric cancer. We determined next which regions of the TP RNA are accessible to ribozymes by employing an RNA mapping strategy, and found that the leader sequences upstream of the AUG start codon appeared to be particularly accessible. A specific ribozyme recognizing the most accessible sequence in the TP RNA with firefly luciferase transcript as a 3' exon was then developed. The specific trans-splicing ribozyme transferred an intended 3' exon tag sequence onto the targeted TP transcripts, resulting in a more than two fold induction of the reporter activity in the presence of TP RNA in mammalian cells, compared to the absence of the target RNA. These results suggest that the Tetrahymena ribozyme can be a potent anti-cancer agent to modify TP RNAs in tumors with a new RNA harboring anti-cancer activity.

Plastid genome of Aster altaicus var. uchiyamae Kitam., an endanger species of Korean asterids

  • Park, Jihye;Shim, Jaekyung;Won, Hyosig;Lee, Jungho
    • Journal of Species Research
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    • 제6권1호
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    • pp.76-90
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    • 2017
  • Aster altaicus var. uchiyamae Kitam. is an endemic taxon of Korea and is protected by law as an endanger taxon. The genetic information of A. altaicus var. uchiyamae is unavailable in Genbank. Here we sequenced chloroplast genome of A. altaicus var. uchiyamae. The cp-genome of Aster altaicus var. uchiyamae was 152,446 bps in size: LSC was 84,240 bps, IR 25,005 bps, SSC 18,196 bps. The cp-genome contains 112 genes and 21 introns consisted of 79 protein coding genes(PCGs), 4 RNA genes, and 29 tRNA genes, with 20 group II introns and one group I intron. There were three pseudo-genes including ${\psi}$-ycf1, ${\psi}$-rps19, and ${\psi}$-trnT_GGU. Eighteen genes, five introns, and parts of two genes and an intron are found within the IR, which has two copies. The cp-DNA of Aster altaicus var. uchiyamae is distinguished from A. spathulifolius, only known cp-genome of the genus Aster, by 172 SNP in genic regions of 43 PCGs and 21 indels in 11 PCGs and SSU. The chloroplast genome sequence was deposited at GenBank (KX35265).

The complete plastid genome of Scopolia parviflora (Dunn.) Nakai (Solanaceae)

  • Park, Jin Hee;Lee, Jungho
    • 식물분류학회지
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    • 제46권1호
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    • pp.60-64
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    • 2016
  • Scopolia parviflora of the family Solanaceae is an endemic species of Korea and a traditional Korean medicinal plant. The plastid genome was sequenced by next-generation sequencing (NGS) method. The characterized cp genome is 156,193 bp in size; the large single-copy (LSC) region is 86,364 bp, the inverted repeat (IR) is 25,905 bp, and the small single copy (SSC) region is 18,019 bp. The overall GC content of the plastid genome amounts to 37.61%. The cp genome contains 113 genes and 21 introns, including 80 proteincoding genes, four RNA genes, 30 tRNA genes, 20 group II introns, and one group I intron. A phylogenetic analysis showed that Scopolia parviflora was closely related to Hyoscyamus niger.

An RNA Mapping Strategy to Identify Ribozyme-Accessible Sites on the Catalytic Subunit of Mouse Telomerase

  • Song, Min-Sun;Lee, Seong-Wook
    • Genomics & Informatics
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    • 제5권1호
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    • pp.32-35
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    • 2007
  • Telomerase reverse transcriptase (TERT) is an enzymatic ribonucleoprotein that prolongs the replicative life span of cells by maintaining protective structures at the ends of eukaryotic chromosomes. Telomerase activity is highly up-regulated in 85-90% of human cancers, and is predominately regulated by hTERT expression. In contrast, most normal somatic tissues in humans express low or undetectable levels of telomerase activity. This expression profile identifies TERT as a potential anticancer target. By using an RNA mapping strategy based on a trans-splicing ribozyme library, we identified the regions of mouse TERT (mTERT) RNA that were accessible to ribozymes. We found that particularly accessible sites were present downstream of the AUG start codon. This mTERTspecific ribozyme will be useful for validation of the RNA replacement as cancer gene therapy approach in mouse model with syngeneic tumors.

Tracing the footprints of the ABCDE model of flowering in Phalaenopsis equestris (Schauer) Rchb.f. (Orchidaceae)

  • Himani, Himani;Ramkumar, Thakku R.;Tyagi, Shivi;Sharma, Himanshu;Upadhyay, Santosh K.;Sembi, Jaspreet K.
    • Journal of Plant Biotechnology
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    • 제46권4호
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    • pp.255-273
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    • 2019
  • Orchids are indispensable to the floriculture industry due to their unique floral organization. The flowers have two outer whorls of tepals including a lip (labellum), and two inner whorls, pollinia and gynostemiun (column). The floral organization and development is controlled at the molecular level, mainly by the MADS-box gene family, comprising homeotic genes divided into type I and type II groups. The type I group has four sub-groups, Mα, Mβ, Mγ, and Mδ, playing roles in seed, embryo, and female reproductive organ development; the type II group genes form classes A, B, C, D, and E, which are a part of the MIKCC subgroup with specific roles in florigenesis and organization. The coordinated functioning of these classes regulates the development of various floral whorls. The availability of genome and transcriptome sequence data for Phalaenopsis equestris offers an opportunity to validate the ABCDE model of flower development. Hence, this study sought to characterize the MADS-box gene family and elucidate of the ABCDE model. A total of 48 identified MADS-box proteins, including 20 type I [Mα (12), Mγ (8)] and 28 type II [MIKCC (27), MIKC*(1)] members, were characterized for physico-chemical features and domains and motifs organization. The exon-intron distribution and the upstream cis-regulatory elements in the promoter regions of MADS-box genes were also analysed. The discrete pace of duplication events in type I and type II genes suggested differential evolutionary constraints between groups. The correlation of spatio-temporal expression pattern with the presence of specific cis-regulatory elements and putative protein-protein interaction within the different classes of MADS-box gene family endorse the ABCDE model of floral development.

Comparison Between Phylogenetic Relationships Based on 18S rDNA Sequences and Growth by Salinity of Chlorella-like Species (Chlorophyta)

  • Lee, Hye-Jung;Hur, Sung-Bum
    • Fisheries and Aquatic Sciences
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    • 제15권2호
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    • pp.125-135
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    • 2012
  • This study was carried out to understand the correlation between phylogenetic relationships based on 18S rDNA sequences and growth by salinity of Chlorella-like species. The 18S rDNA sequences of 71 Chlorella-like species which were mainly collected from Korean waters were analyzed. The 18S rDNA sequences of Chlorella-like species were divided into three groups (group A, B and C) and group B was further divided into three subgroups (subgroup B-1, B-2 and B-3). Thirty-seven Chlorella-like species in group A grew well at high salinity (32 psu) but the other groups grew well in freshwater. The sequence identities of the species in group A and B were 97.2-99.5%, but those of 6 species in group C ("Chlorella" saccharophila), which contained group I intron sequences region were 75.0-75.4%. Two representative species of each group were cultured at different salinities (0, 16 and 32 psu) to examine the correlation between the molecular phylogenetic groups and the phenotypic characteristics on cell growth and size by different salinities. The size of cell cultured at different salinities varied according to the species of each molecular phylogenetic group. The size of "Chlorella" saccharophila in group C was bigger and more obviously elliptical rather than that of the other Chlorella-like species. Considering the results on molecular and phenotypic characteristics, the group A and B belonged to Chlorellaceae, but group C was distinctly different from them.

Taxonomic Review of the Genus Echinochloa in Korea (I): Inferred from Sequences of cpDNA and nrDNA

  • Lee, Jeongran;Kim, Chang-Seok;Lee, In-Yong
    • Weed & Turfgrass Science
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    • 제3권3호
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    • pp.183-189
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    • 2014
  • The genus Echinochloa (L.) P. Beauv. comprised of approximately 30-40 species in the tropical and warm temperate regions of the world, including numerous interspecific and intraspecific types which make the genus difficult to identify. As an attempt to identify the species within the genus easier, the taxonomy of the genus Echinochloa, Poaceae in Korea was reviewed on the basis of sequencing data derived from nuclear ribosomal DNA internal transcribed spacer (ITS) and external transcribe spacer and chloroplast DNA trnL intron, trnL-F intergenic spacer and matK regions using a total of 46 accessions representing all the species in Korea. The results of maximum parsimony found separate lineage comprised of E. colona and E. frumentaceae which are not Korean species, but no resolution within Korean Echinochloa species, supporting the suggestion of Yamaguchi group that E. crus-galli, E. oryzoides, and E. esculenta should be considered to belong to the same species. However, the relationship between these three species and the other species, i.e. E. oryzicola should be better understood with more detail studies.