• Journal of the Korean Society of Tobacco Science
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• v.9 no.2
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• pp.11-24
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• 1987

Lines were developed from the two crosses, BY4 X NC 82 and BY 4 X BY 104, by bulk, backcross and anther-derived dihaploid methods of breeding , and their variations in major agronomic, chemical characters, heritability, and response to selection were compared. 1. The anther-derived dihaploid lines showed a greater genetic variability and heritability in characters investigated than the lines developed by the other two methods of breeding . However, those were Inferior In agronomic characters and yielded 15.4% less leaf tobacco than the lines developed by the bulk method. 2. The lines developed by bulk method were higher In the frequency of lines resistant to bacterial wilt and in the yield, but Its lines appeared later flowering. inferior leaf Quality, and higher total nitrogen contents than those developed by the backcross method of breeding. 3. In the population of the lines developed by the backcross method, bacterial wilt resistant lines were less frequent, but the lines with a good leaf quality were more frequent.

• Animal cells and systems
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• v.9 no.1
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• pp.27-35
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• 2005

Bupleurum euphorbioides is isolated and restricted to high mountains in Korea northeastern China. Its conservation depends on whether it is threatened by inbreeding or a loss of genetic diversity. We compared the genetic variability in B. euphorbioides with B. longiradiatum, a widespread congener, to understand how they differ in their population genetic structure. Although B. euphorbioides showed a little lower genetic variability than B. longiradiatum, $F_{IS}$ statistics for most loci were strongly positive in both B. euphorbioides (0.445) and B. longiradiatum (0.553). In addition, B. euphorbioides showed higher mean $F_{ST}$ value than B. longiradiatum (0.297 vs 0.194). It might be due to the polycarpic nature of B. longiradiatum, which holds higher genetic potentials effectively in homogeneous environment than the monocarpic B. euphorbioides. The results suggested that B. euphorbioides is a genetically viable species, and that they are threatened primarily by environmental factor.

• Molecules and Cells
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• v.42 no.3
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• pp.189-199
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• 2019

Cell-to-cell variability in gene expression exists even in a homogeneous population of cells. Dissecting such cellular heterogeneity within a biological system is a prerequisite for understanding how a biological system is developed, homeostatically regulated, and responds to external perturbations. Single-cell RNA sequencing (scRNA-seq) allows the quantitative and unbiased characterization of cellular heterogeneity by providing genome-wide molecular profiles from tens of thousands of individual cells. A major question in analyzing scRNA-seq data is how to account for the observed cell-to-cell variability. In this review, we provide an overview of scRNA-seq protocols, computational approaches for dissecting cellular heterogeneity, and future directions of single-cell transcriptomic analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.91-96
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• 2005

Proper choice of source populations contributes to the ultimate success of selection for genetic improvement. The source population should possess the most desirable alleles at as many loci as possible for intra population improvement. Such desirable alleles can be intensified by introgression of exotic germ plasm into locally adapted ones through hybridization followed by selection. The objectives of this study were to determine the mean performance, genetic variability $({\sigma}^2G)$ and heritability of fresh ear yield and other important traits within two sweet corn source populations, $BC1-10{\times}Syn-II$ and BC2-10. One hundred selfed progenies from each of the two source populations were evaluated in a $10\times10$ lattice design, at the Institute of Bioscience (IBS) Farm, University of Putra Malaysia (UPM) following the recommended cultural practices. Significant differences among selfed progenies within $BC1-10{\times}Syn-II$ were observed for all traits, while differences among selfed progenies within BC2-10 were noted for fresh ear yield, ear length, ear diameter, number of kernels per row, ear height, days to tasseling and days to silking. Progenies developed from $BC1-10{\times}Syn-II$ population had higher estimates of ${\sigma}^2G$ than did progenies from BC2-10 population for number of kernel rows per ear, total soluble solids, plant height, days to tasseling and days to silking, showing that selection to improve these traits would be more effective in selfed progenies of $BC1-10{\times}Syn-II$ than that in BC2-10. On the other hand, progenies developed from BC2-10 population had higher estimates of ${\sigma}^2G$ for ear length, ear diameter and ear height, indicating that progenies from this population would have better genetic gain than $BC1-10{\times}Syn-II$. Comparable estimates of genetic variance were found for fresh ear yield, and number of kernels per row, indicating that genetic improvement of the two source populations is expected to produce similar genetic gains for these two traits. Therefore, selfed progenies developed from both source populations could be used to improve the two populations for various traits and thereby develop superior genotypes for immediate use in the production system.

• Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.186-190
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• 2007

We examined the genetic variability of Asian chum salmon (Oncorhynchus keta) populations using nuclear microsatellite (ms) DNA analysis with four polymorphic loci (OKM4, OKM5, OKM7, and OKM8) in 397 individuals from nine populations, including one in Korea, seven in Japan, and one in Russia. The msDNA gene diversity was highest in the Japanese populations, suggesting greater genetic variation in the populations in Japan than in populations in Korea and Russia. The pairwise $F_{ST}$ estimates based on our msDNA data showed that the Korean population was genetically different from the Japanese and Russian populations, and there were higher $F_{ST}$ estimates between Hokkaido and Honshu populations than between other population pairs. A neighbor-joining tree showed that the Korean population was distinct from two other clusters, representing the populations in Honshu and the populations in Hokkaido and Russia. These results suggest that the observed population genetic patterns of Asian chum salmon might be influenced by low or restricted gene flow.

• Animal cells and systems
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• v.4 no.1
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• pp.39-44
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• 2000

To assess the genetic diversity and population structure of Korean K. borealis, allozyme analysis was performed. The average genetic variability of Korean K. borealis populations was %P=13.2, Ho=0.048, and He=0.045. This value was the lowest in comparison with other Korean amphibian species studied. Also, the value was much lower than that of a reference population from Chinese K. borealis (%P=50, Ho=0.125, He=0.172). Wright's F-statistics showed that Korean K. borealis has distinctly low level of gene flow among regional populations (F$_{ST}$=0.339, Nm=0.487) in comparison with other Korean amphibian species studied. However, the average level of genetic divergence among Korean K. borealis populations was moderate (Nei's D=0.020). Therefore, it appeared that low levels of genetic diversity (He=0.045) and gene flow (Nm=0.487) among regional populations ave probably due to the results of decreasing population size and patchy distribution of this species in Korea.

• Phonetics and Speech Sciences
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• v.9 no.3
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• pp.25-32
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• 2017

Besides their effect on the f0 contour of the following vowel, Korean stops are undergoing a sound change in which a partial or complete consonantal merger on voice onset time (VOT) is taking place between aspirated and lax stops. Many previous studies on sound change have mainly focused on group-normative effects, that is, effects that are representative of the population as a whole. Few systematic quantitative studies of change in adult individuals have been carried out. The current study examines whether the sound change holds for individual speakers. It focuses on inter-speaker and intra-speaker variability on sound change in contemporary Korean. Speech data were collected for thirteen Seoul Korean speakers studying abroad in America. In order to minimize the possible effects of speech production, socio-phonetic factors such as age, gender, dialect, speech rate, and L2 exposure period were controlled when recruiting participants. The results showed that, for nine out of thirteen speakers, the consonantal merger is taking place between the aspirated and lax stop in terms of VOT. There were also intra-speaker variations on the merger in three aspects: First, is the consonantal (VOT) merger between the two stops is in progress or not? Second, are VOTs for aspirated stops getting shorter or not (i.e., the aspirated-shortening process)? Third, are VOTs for lax stops getting longer or not (i.e., the lax-lengthening process)? The results of remarkable inter-speaker and intra-speaker variability indicate a synchronous speech sound change of the stop system in contemporary Korean. Some speakers are early adopters or active propagators of sound change whereas others are not. Further study is necessary to see whether the inter-speaker differences exceed intra-speaker differences in sound change.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.61-72
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• 2007

The relationship between North Pacific chum salmon (Oncorhynchus keta) population and climate variability was investigated in the North Pacific ecosystem. Time-series for the Aleutian Low Pressure, Southern Oscillation, Arctic Oscillation, and Pacific Decadal Oscillation (PDO) indices dating back to 1950 are compared with the chum salmon catch using a cross-correlation function (CCF) and cumulative sum (CuSum) of anomalies. The results of CCF and CuSum analyses indicated that there was a major change in climate during the mid 1970s, and that the chum salmon population responded to this climate event with a time-lag. The PDO and chum salmon returns showed a highly significant correlation with a time-lag of 3 years, while the AOI with a time-lag of $6{\sim}7$ years. The favorable environments for fry chum salmon might cause better growth in the coastal areas, but higher growth rate during the early stage does not seem to be related to the improved return rate of spawning adults. Rather, growth in the Okhotsk Sea or the Bering Sea during immature stages has a significant correlation with return rate, which implies the size-related mortality process. The development of a local climate index is necessary to elucidate the effect of climate variability on the marine ecosystem around the Korean Peninsula.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.9
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• pp.1369-1377
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• 2020

Objective: The main objectives of the present study were to assess the genetic diversity, population structure and to appraise the efficiency of ongoing selective breeding program in the closed nucleus herd of Nellore sheep through pedigree analysis. Methods: Information utilized in the study was collected from the pedigree records of Livestock Research Station, Palamaner during the period from 1989 to 2016. Genealogical parameters like generation interval, pedigree completeness, inbreeding level, average relatedness among the animals and genetic conservation index were estimated based on gene origin probabilities. Lambs born during 2012 and 2016 were considered as reference population. Two animal models either with the use of F_i or ΔF_i as linear co-variables were evaluated to know the effects of inbreeding on the growth traits of Nellore sheep. Results: Average generation interval and realized effective population size for the reference cohort were estimated as 3.38±0.10 and 91.56±1.58, respectively and the average inbreeding coefficient for reference population was 3.32%. Similarly, the effective number of founders, ancestors and founder genome equivalent of the reference population were observed as 47, 37, and 22.48, respectively. Fifty per cent of the genetic variability was explained by 14 influential ancestors in the reference cohort. The ratio f_e/f_a obtained in the study was 1.21, which is an indicator of bottlenecks in the population. The number of equivalent generations obtained in the study was 4.23 and this estimate suggested the fair depth of the pedigree. Conclusion: Study suggested that the population had decent levels of genetic diversity and a non-significant influence of inbreeding coefficient on growth traits of Nellore lambs. However, small portion of genetic diversity was lost due to a disproportionate contribution of founders and bottlenecks. Hence, breeding strategies which improve the genetic gain, widens the selection process and with optimum levels of inbreeding are recommended for the herd.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1197-1203
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• 2004

This study deals with the characterization of three populations (two hatchery and one natural) of Indian major carps Catla catla and Labeo rohita from different locations in India. The genetics of Indian major carps has been completely obscure and this is the first report on comparative allozyme variations in natural and hatchery population. The total 10 biochemical genetic markers used to measure interspecific and intraspecific level of diversity. The allele frequency data indicate different level of genetic variability in three populations. The hatchery population exhibited least polymorphism, low level of heterozygosity and genetic diversity.