• Genomics & Informatics
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• v.5 no.1
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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.

• Journal of Life Science
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• v.10 no.2
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• pp.12-13
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• 2000

A human-specific retroposon SINE-R.C2 has been derived from a human endogenous retrovirus HER V-K 10. It is absent in the genome of nonhuman primates and present within the third intron of the human C2 gene that is located in the class III region of the major histocompatibility complex. In the present study, we determined the regional location of the human C2 gene. The analysis of the Genebridge 4 radiation hybrid mapping panel using PCR amplification located the C2 gene between D6S1422 (10.1 cR) and CHLC.GATA4A03 (21.3) with a lod score of>3.0. This allowed us to localize C2 gene on the human chromosome 6 band p21.31.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.2
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• pp.109-127
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• 2014

Maize is one of the most important food and feed crops in the world including Southeast Asia. In spite of numberous efforts with conventional breeding, the maize productions remain low and the loss of yields by drought and downy mildew are still severe in Asia. Genetic improvement of maize has been performed with molecular marker and genetic engineering. Because maize is one of the most widely studied crop for its own genome and has tremendous diversity and variant, maize is considered as a forefront crop in development and estimation of molecular markers for agricultural useful trait in genetics and breeding. Using QTL (Quantitative Trait Loci) and MAS (Marker Assisted Breeding), molecular breeders are able to accelerate the development of drought tolerance or downy mildew resistance maize genotype. The present paper overviews QTL/MAS approaches towards improvement of maize production against drought and downy mildew. We also discuss here the trends and importance of molecular marker and mapping population in maize breeding.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1822-1830
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• 2002

The microsatellites are the short tandem repeats of 1 to 6 bp long monomer sequences that are repeated several times. These short tandem repeats are considered to be generated by the slipped strand mispairing. Based on the unique capability of alternating purine-pyrimidine residues to form Z-DNA, the possible role of the microsatellites in gene regulation has been proposed. The microsatellites are highly polymorphic, follow Mendelian inheritance and are evenly distributed throughout the genomes of eukaryotes. They are easy to isolate and the polymerase chain reaction based typing of the alleles can be readily automated. These properties make them the preferred markers for comparison of the genetic structure of the closely related breeds/populations; very high-resolution genetic mapping and parentage testing etc. The microsatellites have rapidly replaced the restriction fragment length polymorphism (RFLP) and the random amplified polymorphic DNA (RAPD) in most applications in the population genetics studies in most species, including the various farm animals viz. cattle, buffalo, goat, sheep and pigs etc. More and more reports are now available describing the use of microsatellites in pigs ranging from measurement of genetic variation between breeds/populations, developing high resolution genetic maps to identifying and mapping genes of biological and economic importance.

• Reproductive and Developmental Biology
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• v.28 no.2
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• pp.107-112
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• 2004

Molecular genetic markers were genotyped used to detect chromosomal regions which contain economically important traits such as growth traits in pigs. Three generation resource population was constructed from a cross between the Korean native boars and Landrace sows. A total of 193 F2 animals from intercross of F1 were produced. Phenotypic data on 7 traits, birth weight, body weight at 3, 5, 12, 30 weeks of age, live empty weight were collected for F2 animals. Animals including grandparents (F0), parents (F1), offspring (F2) were genotyped for 194 microsatellite markers covering from chromosome 1 to 18. Quantitative trait locus analyses were performed using interval mapping by regression under line-cross model. To characterize presence of imprinting, genetic full model in which dominance, additive and imprinting effect were included was fitted in this analysis. Significance thresholds were determined by permutation test. Using imprinting full model, four QTL with expression of imprinted effect were detected at 5% chromosome-wide significance level for growth traits on chromosome 1, 5, 7, 13, 14, and 16.

• The Plant Pathology Journal
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• v.17 no.2
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• pp.67-70
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• 2001

Medicago truncatula is a diploid legume plant related to the forage crop alfalfa. Recently, it has been chosen as a model species for genomic studies due to its small genome, self-fertility, short generation time, and high transformation efficiency. M. truncatula engages in symbiosis with nitrogen-fixing soil bacterium Rhizobium meliloti. M. truncatula mutants that are defective in nodulation and developmental processes have been generated. Some of these mutants exhibited altered phenotypes in symbiotic responses such as root hair deformation, expression of nodulin genes, and calcium spiking. Thus, the genes controlling these traits are likely to encode functions that are required for Nod-factor signal transduction pathways. To facilitate genome analysis and map-based cloning of symbiotic genes, a bacterial artificial chromosome library was constructed. An efficient polymerase chain reaction-based screening of the library was devised to fasten physical mapping of specific genomic regions. As a genomics approach, comparative mapping revealed high levels of macro- and microsynteny between M. truncatula and other legume genomes. Expressed sequence tags and microarray profiles reflecting the genetic and biochemical events associated with the development and environmental interactions of M. truncatula are assembled in the databases. Together, these genomics programs will help enrich our understanding of the legume biology.

• Molecules and Cells
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• v.20 no.2
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• pp.201-209
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• 2005

We have constructed an AFLP-based linkage map of Japanese red pine (Pinus densiflora Siebold et Zucc.) using haploid DNA samples of 96 megagametophytes from a single maternal tree, selection clone Kyungbuk 4. Twenty-eight primer pairs generated a total of 5,780 AFLP fragments. Five hundreds and thirteen fragments were verified as genetic markers with two alleles by their Mendelian segregation. At the linkage criteria LOD 4.0 and maximum recombination fraction 0.25(${\theta}$), a total of 152 markers constituted 25 framework maps for 19 major linkage groups. The maps spanned a total length of 2,341 cM with an average framework marker spacing of 18.4 cM. The estimated genome size was 2,662 cM. With an assumption of equal marker density, 82.2% of the estimated genome would be within 10 cM of one of the 230 linked markers, and 68.1% would be within 10 cM of one of the 152 framework markers. We evaluated map completeness in terms of LOD value, marker density, genome length, and map coverage. The resulting map will provide crucial information for future genomic studies of the Japanese red pine, in particular for QTL mapping of economically important breeding target traits.

• Molecules and Cells
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• v.24 no.3
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• pp.394-408
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• 2007

Several genes/QTLs governing resistance/tolerance to abiotic and biotic stresses have been reported and mapped in rice. A QTL for submergence tolerance was found to be co-located with a major QTL for broad-spectrum bacterial leaf blight (bs-blb) resistance on the long arm of chromosome 5 in indica cultivars FR13A and IET8585. Using the Nipponbare (japonica) and 93-11 (indica) genome sequences, we identified, in silico, candidate genes in the chromosomal region [Kottapalli et al. (2006)]. Transcriptional profiling of FR13A and IET8585 using a rice 22K oligo array validated the above findings. Based on in silico analysis and arraying we observed that both cultivars respond to the above stresses through a common signaling system involving protein kinases, adenosine mono phosphate kinase, leucine rich repeat, PDZ/DHR/GLGF, and response regulator receiver protein. The combined approaches suggest that transcription factor EREBP on long arm of chromosome 5 regulates both submergence tolerance and blb resistance. Pyruvate decarboxylase and alcohol dehydrogenase, co-located in the same region, are candidate downstream genes for submergence tolerance at the seedling stage, and t-snare for bs-blb resistance. We also detected up-regulation of novel defense/stress-related genes including those encoding fumaryl aceto acetate (FAA) hydrolase, scramblase, and galactose oxidase, in response to the imposed stresses.

• BMB Reports
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• v.36 no.6
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• pp.538-544
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• 2003

The hepatitis C virus (HCV) is a major causative agent of chronic hepatitis and hepatocellular carcinoma. The development of alternative antiviral therapies is warranted because current treatments for the HCV infection affect only a limited number of patients and lead to significant toxicities. The HCV genome is exclusively present in the RNA form; therefore, ribozyme strategies to target certain HCV sequences have been proposed as anti-HCV treatments. In this study, we determined which regions of the internal ribosome entry site (IRES) of HCV are accessible to ribozymes by employing an RNA mapping strategy that is based on a trans-splicing ribozyme library. We then discovered that the loop regions of the domain IIIb of HCV IRES appeared to be particularly accessible. Moreover, to verify if the target sites that were predicted to be accessible are truly the most accessible, we assessed the ribozyme activities by comparing not only the trans-splicing activities in vitro but also the trans-cleavage activities in cells of several ribozymes that targeted different sites. The ribozyme that could target the most accessible site identified by mapping studies was then the most active with high fidelity in cells as well as in vitro. These results demonstrate that the RNA mapping strategy represents an effective method to determine the accessible regions of target RNAs and have important implications for the development of various antiviral therapies which are based on RNA such as ribozyme, antisense, or siRNA.

• Journal of Embryo Transfer
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• v.19 no.3
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• pp.291-299
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• 2004

Characterization of quantitative trait loci (QTL) was investigated in the experimental cross population between Berkshire and Yorkshire breed. A total of 512 F$_2$ offspring from 65 matting of F$_1$ parents were phenotyped the carcass traits included average daily gain (ADG), average backfat thickness (ABF), tenth rip backfat thickness (TRF), loin eye area (LEA), and last rip backfat thickness (LRF). All animals were genotyped for 125 markers across the genome. Marker linkage maps were derived and used in QTL analysis based on line cross least squares regression interval mapping. A decision tree to identify QTL with imprinting effects was developed based on tests against the Mendelian mode of QTL expression. To set the evidence of QTL presence, empirical significance thresholds were derived at chromosome-wise and genome-wise levels using specialized permutation strategies. Significance thresholds derived by the permutation test were validated in the data set based on simulation of a pedigree and data structure similar to the Berkshire-Yorkshire population. Genome scan revealed significant evidences for 13 imprinted QTLs affecting growth and body compositions of which nine were identified to be QTL with paternally expressed inheritance mode. Four of QTLs in the loin eye area (LEA), and tenth rip backfat thickness (TRF), a maternally expressed QTL were found on chromosome 10 and 12. These results support the useful statistical models to analyse the imprinting far the QTLs related carcass trait.