• Journal of Life Science
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• v.22 no.10
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• pp.1428-1433
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• 2012

Longevity is an exciting but difficult subject to study because it is determined by complex processes that require the coordinated action of several genetic factors as well as physiological and environmental influences. Genetic approaches have been applied to animal models to identify the molecular mechanism responsible for longevity. Several experimental model organisms obtained over the last decades suggest that the complete deletion of a single gene by gene targeting has proven to be an invaluable tool for the discovery of the mechanisms underlying longevity. The first discovery of long-lived mutants came from Caenorhabditis elegans research, which identified the insulin/IGF-1 pathway as responsible for longevity in this worm. IGF-1 is a multifunctional polypeptide that has sequence similarity to insulin and is involved in normal growth and development of cells. Several factors in the IGF-1 system have since been studied by gene targeting in the control of longevity in lower species, including nematode and fruit fly. In addition, significant progress has been made using mice models to extend the lifespan by targeted mutations that interfere with growth hormone/IGF-1 and IGF-1 signaling cascades. A recent finding that IGF-1 is involved in aging in mice was achieved by using liver-specific knockout mutant mice, and this clearly demonstrated that the IGF-1 signal pathway can extend the lifespan in both invertebrates and vertebrate models. Although the underlying molecular mechanisms for the control of longevity are not fully understood, it is widely accepted that reduced IGF-1 signaling plays an important role in the control of aging and longevity. Several genes involved in the IGF-1 signaling system are reviewed in relation to longevity in genetically modified mice models.

• Journal of Life Science
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• v.27 no.9
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• pp.1003-1010
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• 2017

An open reading frame coding for mannanase predicted from the partial genomic sequence of Paenibacillus woosongensis was cloned into Escherichia coli by polymerase chain reaction amplification, and completely sequenced. This mannanase gene, designated man26AT, consisted of 3,162 nucleotides encoding a polypeptide of 1,053 amino acid residues. Based on the deduced amino acid sequence, Man26AT was identified as a modular enzyme, which included a catalytic domain belonging to the glycosyl hydrolase family 26 and two carbohydrate-binding modules, CBM27 and CBM11. The amino acid sequence of Man26AT was homologous to that of several putative mannanases, with identity of 81% for P. ihumii and identity of less than 57% for other strains of Paenibacillus. A cell-free extract of recombinant E. coli carrying the man26AT gene showed maximal mannanase activity at $55^{\circ}C$ and pH 5.5. The enzyme retained above 80% of maximal activity after preincubation for 1 h at $50^{\circ}C$. Man26AT was comparably active on locust bean gum (LBG), galactomanan, and kojac glucomannan, whereas it did not exhibit activity on carboxymethylcellulose, xylan, or para-nitrophenyl-${\beta}$-mannopyranoside. The common end products liberated from mannooligosaccharides, including mannotriose, mannotetraose, mannopentaose, and mannohexaose, or LBG by Man26AT were mannose, mannobiose, and mannotriose. Mannooligosacchrides larger than mannotriose were found in enzymatic hydrolyzates of LBG and guar gum, respectively. However, Man26AT was unable to hydrolyze mannobiose. Man26AT was intracellularly degraded into at least three active proteins with different molecular masses by zymogram.

• Korean Journal of Microbiology
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• v.53 no.1
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• pp.1-8
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• 2017

Measles virus is a highly contagious, exanthematic virus, preventable by the use of an effective live-attenuated vaccine. However, measles virus remains endemic in many area of the world causing nearly 200,000 deaths per year and still a major cause of child mortality, mostly in developing countries. In March 2014, Republic of Korea was certified as a 'national measles elimination' by the WHO as a result of a high-quality case-based surveillance system and population immunity, which was achieved by a high vaccination rate (>95.0% since 1996). But, since the beginning of 2014, the Gyeonggi province has experienced a resurgence of measles cases. In this study, we investigated the characteristics of measles viruses isolated from confirmed measles in Gyeonggi province during January 1, 2014 ~ July 31, 2014, 60 isolates were obtained from 72 confirmed measles specimens. Genotypic distributions and genetic diversities of isolated measles virus were analyzed by sequencing of nucleoprotein (N) gene. 58 (96.7%) imported cases were identified. The predominant genotype was B3, which reflects the circulating measles virus in adjacent countries. The sequences of nucleoprotein (N) gene of isolated MeV were showed that the strains characterized showed the highest degree of identity (99%) with the Philippine related strains in 2013-2014. Therefore, infected traveler returning from the Philippines transmitted secondary infection in Korea.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.295-301
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• 2011

Aquaporin is a water channel protein, which is classified as Major Intrinsic Protein (MIP), found in almost all organisms from bacteria to human. To date, more than 200 members of this family were identified. There are two major categories of MIP channels, orthodox aquaporins and aquaglyceroporins, which facilitate the diffusion across biological membranes of water or glycerol and other uncharged compounds, respectively. The full genome sequencing of various fungal species revealed 3 to 5 aquaporins in their genome. Although some functions of aquaporins found in yeast were characterized, however, no functional characteristics were studied so far in filamentous fungi, including Aspergillus sp. In this study, one orthodox aquaporin homolog gene, aqpA, and four aquaglyceroporin homologs, aqpB-E, in a model filamentous fungus Aspergillus nidulans were identified and the function of the aqpA gene was characterized. Knock-out of the aqpA gene didn't show any obvious phenotypic change under the osmotic stress, indicating that the function of the gene does not involved in the osmotic stress response or the function could be redundant. However, the mutant showed antifungal susceptibility resistance phenotype, suggesting that the function of the aqpA gene could be involved in sensing the antifungal substances rather than the osmotic stress response.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.289-292
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• 2018

Using pyrene as the enrichment nutrient, a bacterial strain 10PY1A, was isolated by enrichment culture from oil-contaminated sea sand of Arabian Gulf in Saudi Arabia, and this strain belongs to the species Idiomarina piscisalsi, based on 16S RNA gene sequence analysis. The genome of I. piscisalsi strain 10PY1A contains 2,346 protein-coding sequences and an average GC content of 47.4% in its chromosome (2.59 Mbp). Genes encoding proteins related to the degradation of pyrene were existed in the strain 10PY1A genome, indicating that this strain can be used to degrade polycyclic aromatic hydrocarbons in oil-contaminated marine flora and soil.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.93-103
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• 2023

eDNA, an abbreviation for environmental DNA, means DNA derived from organisms inhabiting in a specific environment. The utilization of eDNA extracted from environmental samples allows for efficient and accurate monitoring of organisms inhabiting the respective environment. Specifically, eDNA obtained from seawater samples can be used to analyze marine biodiversity. After collecting seawater samples and extracting eDNA, metagenome analysis enables the taxonomic and diversity analysis among marine organisms inhabiting the sampled area. This review proposed an overall process of marine biodiversity analysis by utilizing eDNA from seawater. Currently, the application of eDNA for analyzing marine biodiversity in domestic setting is not yet widespread. This review can contribute to establishment of marine eDNA research methods in Korea, providing valuable assistance in standardizing the use of eDNA in marine biodiversity studies.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.167-173
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• 2007

To study the transcriptional mechanisms by which expression of the murine glial cell-derived neurotrophic factor inducible transcription factor (mGIF) gene is regulated, a murine genomic clone was iso-lated using a mGIF cDNA as probe. A 13-kb genomic fragment, which comprises 4-kb upstream of the transcription initiation site was sequenced. The promoter region lacks a TATA box and CAAT box, is rich in G+C content, and has multiple putative binding sites for the transcription factor Spl. The mGIF gene also has consensus sequences for AP2 binding sites. The transcriptional activity of five deletion mutants of a 2.1-kb fragment was analyzed by modulating transcription of the heterologous luciferase gene in the promoterless plasmid pGL2-Basic. All mutants showed significant transcriptional activity in the murine neuroblastoma cell line NB41A3. Transient expression assays suggested the presence of a positive regulator between -213 and -129 while a negative regulator was found in the region between -806 and -214. Relatively strong transcriptional activity was observed in neuronal NB41A3, glial C6 cells and hepatic HepG2, but very weak activity in skeletal muscle C2C12 cells. These findings confirm the tissue-specific activity of the mGIF promoter and suggest that this gene shares structural and functional similarities with the dopamine receptor genes that it regulates.

• Research in Plant Disease
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• v.19 no.4
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• pp.254-258
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• 2013

Fusaric acid (FA) is a mycotoxin produced by Fusarium species. Its toxicity is relatively low but often associated with other mycotoxins, thus enhancing total toxicity. To date, biosynthetic genes or enzymes for FA have not been identified in F. oxysporum. In order to explore the genetic element(s) for FA biosynthesis, restriction enzyme mediated integration (REMI) procedure as an insertional mutagenesis was employed using FA producing-F. oxysporum strains. Genetic transformation of two F. oxysporum strains by REMI yielded more than 7,100 transformants with efficiency of average 3.2 transformants/${\mu}g$ DNA. To develop a screening system using phytotoxicity of FA, eleven various grains and vegetable seeds were tested for germination in cultures containing FA: Kimchi cabbage seed was selected as the most sensitive host. Screening for FA non-producer of F. oxysporum was done by growing each fungal REMI transformant in Czapek-Dox broth for 3 weeks at $25^{\circ}C$ then observing if the Kimchi cabbage seeds germinated in the culture filtrate. Of more than 5,000 REMI transformants screened, fifty-three made the seeds germinated, indicating that they produced little or fewer FA. Among them, twenty-six were analyzed for FA production by HPLC and two turned out to produce less than 1% of FA produced by a wild type strain. Sequencing of genomic DNA regions (252 bp) flanking the vector insertion site revealed an uncharacterized genomic region homologous (93%) to the F. fujikuroi genome. Further study is necessary to determine if the vector insertion sites in FA-deficient mutants are associated with FA production.

• Journal of Life Science
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• v.20 no.1
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• pp.103-112
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• 2010

Pemetrexed has demonstrated clinical activity in non-small cell lung cancer (NSCLC) as well as other solid tumors. It transports into the cells via reduced folate carrier (RFC) and is polyglutamated by folypolyglutamate synthetase (FPGS). Pemetrexed directly inhibits several folate-dependent enzymes such as thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). We investigated the effects of genetic variations and the expression of RFC, FPGS, TS and DHFR enzymes on drug sensitivity to pemetrexed in NSCLC cells. Polymorphisms in RFC, FPGS, and DHFR were genotyped in four NSCLC cells - A549, PC14, HCC-1588, and H226. Real-time RT-PCR and Western blot was performed to evaluate mRNA transcripts and protein of these genes. The cytotoxicity of pemetrexed was measured by SRB assay. In PC14 and H226 cells, increased mRNA expressions of RFC and FPGS were associated with higher cytotoxicity to pemetrexed. 2R/2R genotype of TS and its increased mRNA expression were associated with drug resistance to pemetrexed in A549 cells, whereas 3R/3R genotype in TS with decreased mRNA expression was associated with higher sensitivity in H226 cells. After pemetrexed treatment, an inverse change of DHFR mRNA and protein expression was found. The strongest linkage disequilibrium (LD) was discovered between-1726C>T and -1188A>C SNP of DHFR gene. Our findings suggest the cytotoxic effect of pemetrexed may be associated with genetic polymorphisms and the expression level of genes involved in pemetrexed metabolisms in NSCLC cells.

• Journal of Life Science
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• v.31 no.5
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• pp.453-463
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• 2021

Hearing loss is a group of clinically and genetically heterogeneous disorders characterized by congenital- to adult-onset deafness with frequent additional symptoms such as myopathy, nephropathy, and optic disorders. It is commonly divided into two types: syndromic, with no other symptoms, and nonsyndromic, with other symptoms. Autosomal recessive hearing loss is relatively frequent in Pakistan, which may be due in part to frequent consanguineous marriages. This study was performed by whole exome sequencing to determine the genetic causes in two Pakistani consanguineous families with autosomal recessive hearing loss. We identified a pathogenic homozygous variant (p.Leu326Gln in MYO7A) in a family with prelingual-onset hearing loss and two variants of uncertain significance (p.Val3094Ile in GPR98 and p.Asp56Gly in PLA2G6) in a family with early-onset hearing loss concurrent with muscular atrophy. The missense mutations in MYO7A and PLA2G6 were located in the highly conserved sites, and in silico analyses predicted pathogenicity, while the GPR98 mutation was located in the less conserved site, and most in silico analysis programs predicted its nonpathogenic effect. Homozygosity mapping showed that both alleles of the homozygous mutations identified in each family originated from a single founder; spread from this single source might be due to consanguineous marriages. This study will help provide exact molecular diagnosis and treatment for autosomal recessive hearing loss patients in Pakistan.