• 한국가축번식학회지
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• 제25권4호
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• pp.295-304
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• 2001

양적형질 유전자 좌위 (QTL)의 탐색과 이들의 발현 양상 규명을 위해 Berkshire종과 Yorkshire종 간의 교배를 통해 생산된 F$_2$ 실험집단에서 regression interval mapping이 이루어졌다. 모두 525마리의 F$_2$ 자손들에서 일당 증체량, 평균 등지방 두께, 배장근 단면적이 표현형으로 조사되어 분석에 이용되었으며 모돈의 번식능력에 관련된 QTL 존재 여부 추정을 위해 간접 형질로 인정되고 있는 생시체중과 이유 시 체중을 분석에 포함하였다. 양적형질의 분리 여부를 추론하기 위하여 돼지의 2번 염색체에서 8종의 microsatellite 표지인자가 선택되어 유전자형이 조사되었다. 각각의 유전적 모델에서 산출된 통계량으로부터 QTL 존재 여부와 특정 QTL 발현 양상에 대한 여부를 나타낼 수 있는 인정되는 수준의 type I 오차율을 제어할 수 있는 임계값 (threshold)을 permutation test에 의해 제시하였다. QTL의 존재와 그 QTL의 Imprinting 여부는 부계와 모계를 통해 원가계 1세대의 대립유전자가 전달되는 과정에서 발현되는 특성을 분리시키는 통계적 의형을 설정하여 검정 통계량을 산출하였다. 분석에 이용된 3가지 형질과 연관된 3종류의 QTL 존재 가능성을 돼지의 2번 염색체에서 확인하였으며, 이들 중 평균 등지방 두께와 배장근 단면적에 각각 영향을 미칠 것으로 추론된 2종류의 QTL 발현은 정상적인 Mendelian 유전양식을 따르지 않고 imprinting된다는 증거를 얻어냈다. 또한 이들 imprinting되는 QTL은 이미 imprinting 표현 양식을 가진다고 알려진 IGF II 유전자의 위치와 거의 동일한 염색체강의 지점에서 부계로 전달되는 QTL만이 발현되는 특징을 보이는 것으로 밝혀졌다. 한편 Mendelian 모형과 imprinting 모형 모두에서 유의적인 임계값 이상을 보이는 검정 통계량이 산출된 일당 증체량 연관 QTL은 두 모형간의 적정성 분석을 위한 검정을 퐁해 Mendelian 양식을 따른 것으로 최종 확인되었다.

• Journal of Animal Science and Technology
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• 제46권4호
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• pp.525-536
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• 2004

본 연구는 돼지의 염색체 7번에 존재하는 주요 경제형질에 관여하는 양적형질 유전자좌위(Quantitative trait loci; QTL)를 밝히기 위해 초성위체 표지인자를 이용하여 유전자지도(연관지도) 작성을 수행하였다. 기준집단의 조성은 이형접합성이 높은 기준집단을 조성하기 위하여 유전적 특성이 현격히 다른 우리나라의 재래돼지와 Landrace를 전형매 교배하여 생산된 $F_2$ 183두를 사용하였으며 기준집단에 대해 도축 24시간 후의 pH, 육색, 육즙손실량, 전단력, 가열감량, 조지방, 조회분, 수분, 조단백질 등 육질형질을 조사 및 분석하였다. 염색체 7번의 연관지도는 총 23개의 표지인자로 작성되었으며 암수평균 연관지도 길이는 154.6 cM 이었으며 수컷과 암컷의 연관지도 길이는 각각 169.2 cM과 141.4 cM로 수컷의 연관지도 길이가 암컷의 것보다 27.8 cM 더 길었다. 표지인자간의 최소간격은 SW175와 S0066 표지인자사이로 1.6 cM이었고, 최대간격은 SW2002와 SWR773표지인자사이로서 15.9 cM이었으며 평균간격은 7.02 cM이었다. 본 연구에서는 9개의 육질관련 형질 중 육색과 연관된 2개의 QTL이 확인되었는데 적색도(CIE-a)와 연관된 QTL은 45 cM 영역에서 1% 수준의 통계적 유의성을 나타내었고(Fig. 2), 이 영역에서 불과 3${\sim}$4 cM 떨어진 위치에서 황색도(CIE-b)와 연관된 QTL이 확인되었다. 향후에 본 연구에서 탐색된 QTL 영역에 대하여 고밀도의 유전자 지도 작성을 통하여 특정 형질과 연관된 부분을 계속해서 추적해 나간다면 육색형질을 조절하는 주유전자의 클로닝 및 특성 구명이 가능할 것으로 사료되며 궁극적으로는 돼지의 개량에 효율적으로 활용할 수 있는 표지인자(MAS)의 개발 등도 가능 할 것으로 사료된다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.148-148
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• 2017

Soybean is an important economical resource of protein and oil for human and animals. The genetic basis of seed protein and oil content has been separately characterized in soybean. However, the genetic relationship between seed protein and oil content remains to be elucidated. In this study, we used a combined analysis of phenotypic correlation and linkage mapping to dissect the relationship between seed protein and oil content. A $F_{10:11}$ RIL population containing 222 lines, derived from the cross between two Korean soybean cultivars Seadanbaek as female and Neulchan as male parent, were used in this experiment. Soybean seed analyzed were harvested in three different experimental environments. A genetic linkage map was constructed with 180K SoyaSNP Chip and QTLs of both traits were analyzed using the software QTL IciMapping. QTL analyses for seed protein and oil content were conducted by composite interval mapping across a genome wide genetic map. This study detected four major QTL for oil content located in chromosome 10, 13, 15 and 16 that explained 13.2-19.8% of the phenotypic variation. In addition, 3 major QTL for protein content were detected in chromosome 10, 11 and 16 that explained 40.8~53.2% of the phenotypic variation. A major QTLs was found to be associated with both seed protein and oil content. A major QTL were mapped to soybean chromosomes 16, which were designated qHPO16. These loci have not been previously reported. Our results reveal a signi cant genetic relationship between seed protein and oil fi content traits. The markers linked closely to these major QTLs may be used for selection of soybean varieties with improved seed protein and oil content.

• Asian-Australasian Journal of Animal Sciences
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• 제20권5호
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• pp.669-676
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• 2007

This study was conducted to detect quantitative trait loci (QTL) affecting growth and body composition in an $F_2$ reference population of Korean native pig and Landrace crossbreds. The three-generation mapping population was generated with 411 progeny from 38 $F_2$ full-sib families, and 133 genetic markers were used to produce a sex-average map of the 18 autosomes. The data set was analyzed using least squares Mendelian and parent-of-origin interval-mapping models. Lack-of-fit tests between the models were used to characterize QTL for mode of expressions. A total of 8 (39) QTL were detected at the 5% genome (chromosome)-wise level for the 17 analyzed traits. Of the 47 QTL detected, 21 QTL were classified as Mendelian expressed, 13 QTL as paternally expressed, 6 QTL as maternally expressed, and 7 QTL as partially expressed. Of the detected QTL at 5% genome-wise level, two QTL had Mendelian mode of inheritance on SSC6 and SSC9 for backfat thickness and bone weight, respectively, two QTL were maternally expressed for leather weight and front leg weight on SSC6 and SSC12, respectively, one QTL was paternally expressed for birth weight on SSC4, and three QTL were partially expressed for hot carcass weight and rear leg weight on SSC6, and bone weight on SSC13. Many of the Mendelian QTL had a dominant (complete or overdominant) mode of gene action, and only a few of the QTL were primarily additive, which reflects that heterosis for growth is appreciable in a cross between Korean native pig and Landrace. Our results indicate that alternate breed alleles of growth and body composition QTL are segregating between the two breeds, which could be utilized for genetic improvement of growth via marker-assisted selection.

• Asian-Australasian Journal of Animal Sciences
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• 제16권10호
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• pp.1402-1405
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• 2003

The QTL(quantitative traits loci) linkage mapping of Hanwoo (Korean Cattle) chromosome 6 for daily gain and marbling score was performed using 378 individuals from 18 paternal half-sib families in Hanwoo. Hanwoo chromosome 6 were mapped to total length of 394.2 cM between 28 microsatellite loci using 36 microsatellite primers of BTA 6 linkage group. The QTL analysis for daily gain in Hanwoo showed 8 microsatellite loci (BM3026-5.66, EL03-5.58, BM4311-5.29, ILSTS035-4.50, BMS1242-4.37, BM1329-3.67, BM415-3.11, BMS2460-3.03) in larger than LOD score 3.0. Based on the QTL analysis for marbling score, LOD scores of 12 microsatellite loci (BM415-8.88, BM3026-7.15, ILSTS093-5.45, ILSTS035-4.91, EL03-4.69, BMS690-4.52, BM1329-4.43, BMS511-3.74, BMS1242-3.66, BMS518-3.65, BM4311-3.41, BMC4203-3.36) were found larger than 3.0.

• Asian-Australasian Journal of Animal Sciences
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• 제24권12호
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• pp.1644-1650
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• 2011

This study was conducted to detect quantitative trait loci (QTL) affecting meat quality in an $F_2$ reference population of Korean native pig and Landrace crossbreds. The three-generation mapping population was generated with 411 progeny from 38 $F_2$ full-sib families, and 133 genetic markers were used to produce a sex-average map of the 17 autosomes. The data set was analyzed using least squares Mendelian and parent-of-origin interval-mapping models. Lack-of-fit tests between models were used to characterize the QTL for mode of gene expressions. A total of 10 (32) QTL were detected at the 5% genome (chromosome)-wise level for the analyzed traits. Of the 42 QTL detected, 13 QTL were classified as Mendelian, 10 as paternal, 14 as maternal, and 5 as partial expressed QTL, respectively. Among the QTL detected at 5% genome-wise level, four QTL had Mendelian mode of inheritance on SSCs 5, 10, 12, and 13 for cooking loss, drip loss, crude lipid and crude protein, respectively; two QTL maternal inheritance for pH at 24-h and shear force on SSC11; three QTL paternal inheritance for CIE b and Hunter b on SSC9 and for cooking loss on SSC15; and one QTL partial expression for crude ash on SSC13, respectively. Most of the Mendelian QTL (9 of 13) had a dominant mode of gene action, suggesting potential utilization of heterosis for genetic improvement of meat quality within the cross population via marker-assisted selection.

• Asian-Australasian Journal of Animal Sciences
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• 제32권12호
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• pp.1826-1835
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• 2019

Objective: Testicular growth and development are strongly influenced by androgen. Although both testis weight and plasma testosterone level are inherited traits, the interrelationship between them is not fully established. Males of DDD/Sgn (DDD) mice are known to have extremely heavy testes and very high plasma testosterone level among inbred mouse strains. We dissected the genetic basis of testis weight and analyzed the potential influence of plasma testosterone level in DDD mice. Methods: Quantitative trait loci (QTL) mapping of testis weight was performed with or without considering the influence of plasma testosterone level in reciprocal $F_2$ intercross populations between DDD and C57BL/6J (B6) mice, thereby assessing the influence of testosterone on the effect of testis weight QTL. Candidate genes for testis weight QTL were investigated by next-generation sequencing analysis. Results: Four significant QTL were identified on chromosomes 1, 8, 14, and 17. The DDDderived allele was associated with increased testis weight. The $F_2$ mice were then divided into two groups according to the plasma testosterone level ($F_2$ mice with relatively "low" and "high" testosterone levels), and QTL scans were again performed. Although QTL on chromosome 1 was shared in both $F_2$ mice, QTL on chromosomes 8 and 17 were identified specifically in $F_2$ mice with relatively high testosterone levels. By whole-exome sequencing analysis, we identified one DDD-specific missense mutation Pro29Ser in alpha tubulin acetyltransferase 1 (Atat1). Conclusion: Most of the testis weight QTL expressed stronger phenotypic effect when they were placed on circumstance with high testosterone level. High testosterone influenced the QTL by enhancing the effect of DDD-derived allele and diminishing the effects of B6-derived allele. Since Pro29Ser was not identified in other inbred mouse strains, and since Pro29 in Atat1 has been strongly conserved among mammalian species, Atat1 is a plausible candidate for testis weight QTL on chromosome 17.

• Asian-Australasian Journal of Animal Sciences
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• 제26권11호
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• pp.1536-1544
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• 2013

A least squares regression interval mapping model was derived to detect quantitative trait loci (QTL) with a unique mode of genomic imprinting, polar overdominance (POD), under a breed cross design model in outbred mammals. Tests to differentiate POD QTL from Mendelian, paternal or maternal expression QTL were also developed. To evaluate the power of the POD models and to determine the ability to differentiate POD from non-POD QTL, phenotypic data, marker data and a biallelic QTL were simulated on 512 F2 offspring. When tests for Mendelian versus parent-of-origin expression were performed, most POD QTL were classified as partially imprinted QTL. The application of the series of POD tests showed that more than 90% and 80% of medium and small POD QTL were declared as POD type. However, when breed-origin alleles were segregating in the grand parental breeds, the proportion of declared POD QTL decreased, which was more pronounced in a mating design with a small number of parents ($F_0$ and $F_1$). Non-POD QTL, i.e. with Mendelian or parent-of-origin expression (complete imprinting) inheritance, were well classified (>90%) as non-POD QTL, except for QTL with small effects and paternal or maternal expression in the design with a small number of parents, for which spurious POD QTL were declared.

• Journal of Crop Science and Biotechnology
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• 제11권1호
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• pp.7-12
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• 2008

Quantitative trait loci, a genetic concept for explaining the inheritance of non-Mendelian traits in 1940s, have been realized as particular fragments of chromosome even unique genes in most crops in 21st century. However, only very a small portion of QTL has been screened out by geneticists comparing to a great number of genes underneath the quantitative traits. These identified QTL even have been seldom used into breeding program because crop breeders may not find the QTL in their breeding populations in their field station. Several key points will be proposed to meet the challenges of QTL analysis today: a fine mapping population and the related reference genetic map, QTL evaluation in multiple environments, recognizing real QTL with small genetic effect, map integration.

• Asian-Australasian Journal of Animal Sciences
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• 제18권12호
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• pp.1675-1683
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• 2005

In the process of crossbreeding, the linkage disequilibria between the quantitative trait loci (QTL) and their linked markers were reduced gradually with increasing generations. To study the potential of QTL mapping using the crossbred population, we presented a mixed effect model that treated the mean allelic value of the different founder populations as the fixed effect and the allelic deviation from the population mean as random effect. It was assumed that there were fifty QTLs having effect on the trait variation, the population mean and variance were divided to each QTL in founder generation in our model. Only the additive effect was considered in this model for simulation. Six schemes (S1-S6) of crossbreeding were studied. The selection index was used to evaluate the synthetic breeding value of two traits of the individual in the scheme of S2, S4 and S6, and the individuals with high selection index were chosen as the parents of the next generation. Random selection was used in the scheme of S1, S3 and S5. In this study, we premised a QTL explained 40% of the genetic variance was located in a region of 20 cM by the linkage analysis previously. The log likelihood ratio (log LR) was calculated to determine the presence of a QTL at the particular chromosomal position in each of the generations from the fourth to twentieth. The profiles of log LR and the number of the highest log LR located in the region of 5, 10 and 20 cM were compared between different generations and schemes. The profiles and the correct number reduced gradually with the generations increasing in the schemes of S2, S4 and S6, but both of them increased in the schemes of S1, S3 and S5. From the results, we concluded that the crossbreeding population undergoing random selection was suitable for improving the resolution of QTL mapping. Even experiencing index selection, there was still enough variation existing within the crossbred population before the fourteenth generation that could be used to refine the location of QTL in the chromosome region.