• Journal of Animal Science and Technology
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• v.57 no.12
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• pp.47.1-47.10
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• 2015

Background: Knowledge of linkage disequilibrium (LD) levels among different populations can be used to detect genetic diversity and to investigate the historical changes in population sizes. Availability of large numbers of SNP through new sequencing technologies has provided opportunities for extensive researches in quantifying LD patterns in cattle breeds. The aim of this study was to compare the extent of linkage disequilibrium among Iranian cattle breeds using high density SNP genotyping data. Results: A total of 70 samples, representing seven Iranian indigenous cattle breeds, were genotyped for 777962 SNPs. The average values of LD based on the $r^2$ criterion were computed by grouping all syntenic SNP pairwises for intermarker distances from 0 Kb up to 1 Mb using three distance sets. Average $r^2$ above 0.3 was observed at distances less than 30 Kb for Sistani and Kermani, 20 Kb for Najdi, Taleshi, Kurdi and Sarabi, and 10 Kb for Mazandarani. The LD levels were considerably different among the Iranian cattle breeds and the difference in LD extent was more detectable between the studied breeds at longer distances. Lower level of LD was observed for Mazandarani breed as compared to other breeds indicating larger ancestral population size in this breed. Kermani breed continued to have more slowly LD decay than all of the other breeds after 3 Kb distances. More slowly LD decay was observed in Kurdi and Sarabi breeds at larger distances (>100 Kb) showing that population decline has been more intense in more recent generations for these populations. Conclusions: A wide genetic diversity and different historical background were well reflected in the LD levels among Iranian cattle breeds. More LD fluctuation was observed in the shorter distances (less than 10 Kb) in different cattle populations. Despite of the sample size effects, High LD levels found in this study were in accordance with the presence of inbreeding and population decline in Iranian cattle breeds.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.229-233
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• 1995

The life history, seasonal occurrence of larval population and natural enemies of Tea leaf roller (Caloptilia theivora (Walshingham) were investigated in field-age. C. theivora had 6 generations a year. The developmental periods from egg to adult emergence were 32.1~38.6 days in spring and fall, and 24.8~32.7 days in summer. The average longevities of adults were 8.4~14.5 days in spring and fall, and 6.3~8.6 days in summer. The average number of eggs laid by a female were 55~71 throughout the season. Larval population density of C. theivora showed 3~4 peaks from middle may in 1992 and 1993. However, population density of 194 was pretty low in early season and exhibited a peak in late September-early October. C. theivora overwintered in pupal stage on the leaves. Four hymenopterous parasitoids of C. theivora larvae were identified ; they are Stenomesius japonicus (Ashmead), Sympiesis ringoniellae Kamijo, Elasmus sp., and S. dolichogaster Ashmead which is dominant.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.249-255
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• 1995

These experiments were conducted to investigate the life history and the seasonal fluctuation of population density of tea red spider mite, Tetranychus kanzawai Kishida and to observe its natural enemies in the southern area. Under field-cage conditions, tea red spider mite occurred 11~12 generations. The average periods from egg to adult emergence were 8.7~13.1 days in summer and 12.6~24.9 days in spring and autumn. The average longevities of adults were 15.5~21.9 days in summer and 25.1~31.6 days in spring and autumn. The average number of eggs laid per female were 45.1 in summer and 52.6 in spring and autumn. Tea red spider mite population showed two peaks during April-June, and appeared third or forth peak during October-November. The density of all the stages was the lowest in July through August. Tea red spider mites stayed at lower parts of tea plants in March but they moved to upper parts in April though June, and they again moved to lower parts after autumn. Tea red spider mite overwintered as all stages. Adults were the dominant overwintering stage during this stage. The surveyed natural enemies of the tea red spider mite were 7 species including Amblyseius longispinosus (Evans), A. eharai Amitei et Swirski, Anystis baccarun (L), Agistemus fleschneri Summers, Orius sauteri Poppius, Oligota yasumatsui Kistner and Scolothrips sp.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.1-6
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• 2006

The population shifts of Monilinia fructicola isolates which were resistant to the fungicide benzimidazoles were investigated in four regions of Korea from 1998 to 2000. The isolation frequency of benzimidazole-resistant isolates ranged from 18.8% to 29.6% in Chongdo and from $22.0\%$ to $26.8\%$ in Gyeongsan during the same period. However, the frequency of benzimidazoleresistant isolates was less than $4.0\%$ in Chochiwon and Youngduk during the same period. Benzimidazoleresistant isolates showed cross-resistance among benzimidazoles. On the other hand, none of the isolates showed cross-resistance to diethofencarb and carbendazim. Regardless of the year, the benzimidazole-resistant isolates of $EC_{50}$ higher than 500 $\mug%$ a.i./ml were isolated more frequently in mid and late season than in early season. In an orchard of Gyeongsan that had not been exposed to any fungicides for several years, the population of benzimidazole-resistant isolate had persisted without much fluctuation for three years. These results suggest that benzimidazole resistance of M. fructicola is becoming a problem in controlling brown rot and blossom blight of peach in regions like Chongdo and Gyeongsan.

• Journal of Soil and Groundwater Environment
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• v.21 no.4
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• pp.50-59
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• 2016

Spatial and temporal changes in nitrification activities and distribution of microbial population of ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in paddy soils were investigated. Soil samples were collected in March and October 2015 from rice paddy with and without the presence of confined animal feeding operations. Incubation experiments and quantitative polymerase chain reaction showed that AOA's contribution to nitrification kinetics was much higher in locations where organic nitrogen in animal waste is expected to significantly contribute to overall nitrogen budget, and temporal variations in nitrification kinetics were much smaller for AOA than AOB. These differences were interpreted to indicate that different microbial responses of two microbial populations to the types and concentrations of nitrogen substrates were the main determining factors of nitrification processes in the paddy soils. The copy numbers of ammonium monooxygenase gene showed that AOA colonized the paddy soils in higher numbers than AOB with stable distribution while AOB showed variation especially in March. Although small in numbers, AOB population turned out to exert more influence on nitrification potential than AOA, which was attributed to higher fluctuation in AOB cell numbers and nitrification reaction rate per cells.

• The Korean Journal of Zoology
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• v.19 no.1
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• pp.15-24
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• 1976

The frequency of the second chromosomes bearing deleterious genes in the Anyang natural population of Korea in Drosophila melanogaster was repeatedly estimated during the period from 1971 through 1973. 1) The frequency of lethal and semilethal chromosomes was calculated to be 28.2%, and the frequencies were maintained without fluctuation for three years. 2) Allelism rate between lethal genes isolanted from each year was 0.77% on the average. The rate of elimination of lethal genes $(IQ^2)$ was estimated to be 0.0008. 3) The frequency of sterile gene on the second chromosomes was estimated to be 9.1% for females, 6.8% for males and 2.0% for both sexes, respectively. 4) Recessive visible mutant genes, namely rbl and bw genes, were frequently extracted when the chromosomes were revealed in homozygous. The frequencies of these mutants were found to be 1.3% for bw genes and 2.7% for rbl genes, respectively.

• Korean Journal of Microbiology
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• v.15 no.1
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• pp.20-30
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• 1977

Relationship of soil properties and seasonal variation on microbilogical population to-continuous culture and first-time culture of ginseng was investigated by bimonthly from May 1976 to January 1977. pH and P contents of 2 years continuous culture of soil were higher than other culture plot of soil, and contraty to the above, 2 years first-time culture of ginseng soil was conplot of soil, and contraty to the above, 2 years first-time culture of ginseng soil was contained more potassium contents than other culture plot of soil. In microbiological fluctuation with seasonr in various soil conditions, the population, trends of Fusarium spp., Erwiniaspp., and flourescent Psedudomonas spp. were increased in May and July in general, but decreased in the other month. It was observed that in all type of soil, Fusarium spp. was distributed in abundance in and on rihizosphere, and decreased the propagules numbers as soil depth increase. The numbers of Erwinia spp. and fluorescent Pseudo-monas spp. were distributed greater in numbers on the surface zone of soil depth decreasing the numbers along the soil layer increase, and also in 2years continuous culture of soil especially, a great numbers of Erwinia spp. and fluorescent Pseudomonas were evenly distributed in surface zone and rhizosphere. Ginseng disease with a high incidence of bacterial disease in continuous culture of 2 and 4 years was seemed to be associated with soil bacteria that was high in numbers of Erwinia spp. and fluorescent Pseudomonas spp. in May and July.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.3
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• pp.35-40
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• 1980

In order to evaluate the fluctuation of soybean aphid (Aphis glycines Matsumura) population, six leading soybean cultivars were planted on five different planting dates with three plant spacings. The survey of aphid population and climatical condition were made from June through September in 1978. According to the differences of planting dates and plant spacings the soybean aphid populations were varied, and varietal response to the aphid was significantly different. Counting of aphid infestation on top third trifoliolate leaf seemed to be efficient for the estimation of soybean aphid population.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.35-42
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• 2004

To examine the species composition and population fluctuation of butterflies at Mt. Yudal, Mokpo, we collected butterflies from May, 2001 to April, 2002 by dividing the study site into four subyegions. As a result, seven families comprising 40 species were identified. The patterns of population fluctuations at the four subregions showed that the lower the elevation the higher the number of species and individuals. Monthly fluctuations of buttefly species produced an M-shaped curve, whereas those of individuals produced a monotonic curve with a maximum peak during August. To see effectively the changes of numbers of species and individuals, we calculated the indices of species richness and evenness by subregions and months. As a result, both indices fulfilled the primary criterion of independence and showed more or less negative association: when heterogeneity is higher, evenness is lower. Examination of butterfly populations over long-term periods might provide an evidence of global warming and a guideline to conserve and manage habitats.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.2
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• pp.207-217
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• 2021

Purpose: This study aimed to investigate the seasonal changes in vitamin D levels in a healthy pediatric population living in mid-latitude East Asian urban areas. Methods: A pediatric population was selected from single secondary hospital visitors. Clinical data and serum vitamin D levels were collected retrospectively. Statistical analyses were performed based on the month of the blood sampling date, subject age, and vitamin D supplementation history. The data were categorized into three subgroups based on serum vitamin D levels-adequate (≥30 ng/mL), insufficient (20-29 ng/mL), and deficient (<20 ng/mL). Results: Of the 481 patients, 172 had vitamin D supplementation history. More than 70% of the total study population had inadequate vitamin D levels (<30 ng/mL). The non-supplemented group and the supplemented group showed significantly uneven monthly distribution of the adequate, insufficient, and deficient subgroups. Only the non-supplemented group showed significantly different average vitamin D levels in the summer months compared to the winter months. In the non-supplemented group, vitamin D levels were the lowest in March, the highest in August and September. Significant relevance was noted between vitamin D supplementation status and vitamin D serum level in February and March. There was no significant difference between different age groups in terms of the distribution of vitamin D levels. Conclusion: Currently-widespread vitamin D replacement methods seem to have some effect on increasing the overall serum vitamin D levels, specifically during late winter when natural serum vitamin D levels plunge. However, they are unable to fully compensate the seasonal fluctuation.