• Journal of Life Science
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• v.20 no.10
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• pp.1538-1543
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• 2010

This study was conducted to examine the genetic diversity and population structure of 17 Brassica juncea populations in Korea. The technique of random amplified polymorphic DNA (RAPD) produced 60 polymorphic loci and 18 monomorphic loci. In a simple measure of intraspecies variability by the percentage of polymorphic bands, the Jindo population of Cheonnam showed the highest (29.5%). The cultivar exhibited the lowest variation (12.8%). Mean number of alleles per locus (A) and the effective number of alleles per locus ($A_E$) were 1.221 and 1.167, respectively. As the typical populations of this species were small, isolated, and patchily distributed in their natural populations, they maintained a low level of genetic diversity of fourteen primers. On a per locus basis, total genetic diversity values ($H_T$) and interlocus variation in the within-population genetic diversity ($H_S$) were 0.347 and 0.141, respectively. On a per-locus basis, the proportion of total genetic variation due to differences among populations ($G_{ST}$) was 0.589. This indicated that about 58.9% of the total variation was among populations. The estimate of gene flow, based on $G_{ST}$, was very low among Korean populations of B. juncea ($N_m$=0.617). These results suggest that the geological distance dispersal of wild B. juncea is the best event. RAPD markers are very effective in classifying natural population levels of B. juncea in Korea.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.610-611
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• 2002

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.346.2-346
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• 1998

No Abstract, See Full Text

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.10a
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• pp.62.1-62
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• 1999

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.45.1-45
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• 1999

No Abstract, See Full Text

• Journal of Apiculture
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• v.34 no.1
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• pp.1-6
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• 2019

Honey bees use propolis to defend against invaders and pathogens. Propolis, a resinous mixture, has been widely used for its antibacterial, antifungal and anti-inflammatory properties. This research was carried out to evaluate the propolis productivity in Apis mellifera lines to select superior honeybee lines. For the study, which were collected from three regions in Korea were evaluated for the productivity of propolis. The results showed that, the average propolis per colony was highest in the line P2 (10.1 g/hive), which was inbed line derived from isolated region, compared to other lines. We also measured brood development one the basis of population size of eggs, brood, and adult bees to further probe for relation between population size and propolis yield, in that larger population generally have more foragers. Also, adult population expended more greatly in the line P2 compared to that in the control.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.258-267
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• 2006

Distribution of population densities of heterotrophic bacteria, E. coli, and Salmonella and Shigella in seawater and sediments at 40 stations near Samcheonpo Bay were measured for 3 times from July to December, 2003. Population densities of heterotrophic bacteria in seawater during survey periods were in the range of $1.7{\pm}0.9{\times}10^3{\sim}2.4{\pm}0.9{\times}10^5$ CFU $mL^{-1}$ and the highest density was shown at St. 34 during the sampling period of September, 2003. Population densities of heterotrophic bacteria were shown higher values on September than those of July and December at all sampling stations. Population densities of anaerobic heterotrophic bacteria in sediments during survey periods were in the range of $2.2{\pm}0.2{\times}10^3{\sim}2.0{\pm}0.2{\times}10^5$ CFU $mL^{-1}$ and their population densities at sampling stations far from Samcheonpo Bay measured lower values than those near Samcheonpo Bay. Population densities of anaerobic heterotrophic bacteria in the sediments were not affected by physico-chemical factors of upper water environment. E. coli were detected only at 8 stations in seawater and 4 stations in the sediments among 40 sampling stations on July and were not detected during September and December. Salmonella and Shigella were detected only a few stations on July and September during sampling periods.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.493-503
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• 2015

This study analyzed how spatial distribution of Himantormia lugubris is affected by the microenvironment in the Antarctic Specially Protected Area (ASPA) No. 171 located in the Barton Peninsula of King George Island that belongs to the maritime Antarctic. In order to determine the population structure of H. lugubris growing in Baekje Hill within ASPA No. 171, we counted the individuals of different size groups after dividing the population into 5 growth stages according to mean diameter as follows: ≤ 1 cm, 1-3 cm, 3-5 cm, 5-10 cm, and ≥ 10 cm. The count of H. lugubris individuals in each growth stage was converted into its percentage with respect to the entire population, which yielded the finding that stages 1 through 5 accounted for 32.8%, 25.3%, 15.9%, 22.5%, and 3.5%, respectively. This suggests that the population of H. lugubris in ASPA No. 171 has a stable reverse J-shaped population structure, with the younger individuals outnumbering mature ones. The mean density of H. lugubris was 17.6/0.25 m², mean canopy cover 13.3%, and the mean dry weight 37.8 g/0.25 m². It began to produce spore in the sizes over 3 cm, and most individuals measuring 5-10 cm were adults with sexually mature apothecia. The spatial distribution of H. lugubris was highly heterogeneous. The major factors influencing its distribution and performance were found to be the period covered by snow, wind direction, moisture, size of the substrate, and canopy cover of Usnea spp. Based on these factors, we constructed a prediction model for estimating the spatial distribution of H. lugubris. Conclusively, the major factors for the spatial distribution of H. lugubris were snow, wind, substrate and the competition with Usnea spp. These results are important for understanding of the distribution in the maritime Antarctic and evolution of H. lugubris that claims a unique life history and ecological niche.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.658-675
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• 2016

The environmental characteristics of the habitats, the population structures, ecological niche, life traits and the population demography are used as an essential informations to the effective conservation plans about the target species. We first confirmed a total of 37 populations through 12 years of investigation on the extents, and investigated the environmental factors of habitats and the population structures of the 25 cohorts in 12 regions among them. And, we investigated the population dynamics targeting at 8 cohorts in the population of Daegwanryeong-myeon, Pyeongchang-gun, Gangwon-do. Along with this, we conducted 4 years of cultivation experiments and how pollinators affect the success of reproduction. The results shows that the Paeonia obovata Maxim. was found in a relatively wide range of habitats. For the population structures of the 25 cohorts, there were considerable differences among cohorts, including a case which showed relative stable structure and an extreme case in which only adults were found. The factor that affected the population dynamics during the investigation was thought as a forest gap created in the tree layer. In the cultivation experiment, seedlings grew well in a less soil organic matter. The seed setting rate and the number of seeds generated by visiting pollinators were higher trends. In conclusion, to understand the distribution of the Paeonia obovata Maxim., there needs to be investigated on the other factors that are involved in dispersal factors other than environmental factors, and thus we suggest the necessity of the research on the dispersal vectors. The current Paeonia obovata Maxim. population was thought as a process of expansion after the rapid reduction of the extents in the past. For the effective conservation of the Paeonia obovata Maxim., an endangered plant, we recommend to understand the species through the spatio-temporal expansion, and maintain the health of the ecosystem based on it.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.6
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• pp.772-779
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• 2013

Linkage disequilibrium (LD) plays an important role in genomic selection and mapping quantitative trait loci (QTL). In this study, the pattern of LD and effective population size ($N_e$) were investigated in Chinese beef Simmental cattle. A total of 640 bulls were genotyped with IlluminaBovinSNP50BeadChip and IlluminaBovinHDBeadChip. We estimated LD for each autosomal chromosome at the distance between two random SNPs of <0 to 25 kb, 25 to 50 kb, 50 to 100 kb, 100 to 500 kb, 0.5 to 1 Mb, 1 to 5 Mb and 5 to 10 Mb. The mean values of $r^2$ were 0.30, 0.16 and 0.08, when the separation between SNPs ranged from 0 to 25 kb to 50 to 100 kb and then to 0.5 to 1 Mb, respectively. The LD estimates decreased as the distance increased in SNP pairs, and increased with the increase of minor allelic frequency (MAF) and with the decrease of sample sizes. Estimates of effective population size for Chinese beef Simmental cattle decreased in the past generations and $N_e$ was 73 at five generations ago.