• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.107-112
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• 2006

Two Atractylodes species, A. japonica Koidz. ex Kitam. (AJ) and A. macrocephala Koidz (AM) were used in this study. AJ population had higher amounts of Sesquiterpenoids and stronger tolerance to root rot but less vigor of root growth than AM population. Two populations (AJ and AM) were crossed to make interspecific hybrid population. A total of 98 lines propagated clonally were selected from a cross of AJ and AM, and evaluated for contents of sesquiterpenoids, atractylon (ATLN) and atractylenolide III (AT3) using high performance liquid chromatography (HPLC), and growth characters such as plant height, stem number and root weight. HPLC profiles of the hybrids were compared with those of parent plants, and it demonstrated the production of introgression hybrid by crossing between AJ and AM. Of 98 clonal lines,10 lines were selected by 10% level based on the growth vigor and tolerance to root rot, and AJM2102-51 line showed the heaviest root weight (117.1 g/plant) among them. A total of 98 hybrid lines contained on average $0.16\;{\pm}\;0.10\;mg/g$ of $AT3,\;2.00\;{\pm}\;1.37\;mg/g$ of ATLN, and $2.16\;{\pm}\;1.40\;mg/g$ of total sesquiterpenoids, showing high coefficients of variation (above 65%). Ten lines having high contents of sesquiterpenoids were selected, and AJM2101-15 had the highest amount (9.83 mg/g) of ATLN, and showed 40.8 g/plant of root weight similar to mean value (39.9 g/plant) of hybrid lines. The result showed that the introgression of both characters of vigorous growth from AM and high sesquiterpenoids content from AJ could be possible to make new hybrid lines by crossing between AJ and AM.

• Korea journal of population studies
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• v.16 no.2
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• pp.1-23
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• 1993

Korea fertility level has dropped since the 1960's and speed of decline has accelerated in the 1980's. In the resuls, the growth rate reached to less then 1 percent in 1990 and will be $\ulcorner$0 $\lrcorner$ percent growth in 2021. The total population will increase to 50, 586 thousand persons in 2021 then will decrease. With the rapid fertility decline the age structure of Korean population has changed : while the proportion of child population aged 0-14 is decreasing sharply, that of old-age population aged 65 and over is increasing. Because of the recent increase of sex ratio at birth, the sex structure among the young generation has been destorted; the sex ratio at age 0-4 was as high as high as 112.0 in 1990. The effects of these population phenomena on Korean society are the followings: 1) Old age dependency ratio is increasing rapidly and continuously and will be about 40.0 from the 2050's. 2) Because of the rapid decline of the number of births, the absolute number of the major labour force at age 25-34 will decrease after around 2000 and then from the 2010's become less than that in 1990. 3) Since the large fertility defferentials by womens's educational level have continued and the relation between the educational levels of mothers and children are very strong, level has dropped among higher educated women first when the average fertility level has declined in Korea, the average educational level of the children is may be expected to be relatively low and then the future productivity is will be also low, which causes the decline of 'quality of population. 4) When the high sex ratio at birth (over 110 since 1986) continues, number of brides will be short by over 20 percent from the 2010s, which will bring various kinds of social prblems. Therefore, the counter measures in concrete to relieve the heavy problems are recommended as follows: 1) The extention of the birth intervals, which helps to drop the population growth rate at the same level of number of children per women. 2) The positive supports for out-migrants, which helps to reduce the population size without any destortion of age-sex structure. 3) The defferent supports of family planning for the higher and lower classes, which helps to reduce the gaps between different ferility levels of the classes and to keep and improve the quality of population. 4)population education for both students and adults, which helps to minimize the gap between the private and public requirements.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.39-45
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• 2000

The purpose of this study was conducted to indentified the fixing quality of $CO_2$, the most important greenhouse effect gas, by microalgae Chlorella ellipsoidea in batch test apparatus. The glass flask of $1.4{\ell}$ culture media which was saturated with 99.99% pure $CO_2$ gas was setted water bath of $25^{\circ}C$, 5000Lux, and seeded 100$m\ell$ algae liquid. We checked the change of inorganic carbon concentration and algae population with time in culture media. The result were next: the growth of algae population relied on aquatic IC(inorganic carbon) concentration. And the pH was increased with decrease of IC concentration. The growth of algae population had positive correalation with $CO_2$ concentration, and the coefficient of correlation was 0.982. The specific growth rate($\mu$) of Chlorella ellipsoidea was 1.104/d, the maximum specific growth $rate({\mu}_{max}$) of 9.21/d, and helf velocity constant($K_s$) of $259mg/{\ell}$ by Monod equation.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1472-1477
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• 2013

Microalgae have been regarded as a natural resource for sustainable materials and fuels, as well as for removal of nutrients and micropollutants from wastewater, and their interaction with bacteria in wastewater is a critical factor to consider because of the microbial diversity and complexity in a variety of wastewater conditions. Despite their importance, very little is known about the ecological interactions between algae and bacteria in a wastewater environment. In this study, we characterized the wastewater bacterial community in response to the growth of a Selenastrum gracile UTEX 325 population in a real municipal wastewater environment. The Roche 454 GS-FLX Titanium pyrosequencing technique was used for indepth analysis of amplicons of 16S rRNA genes from different conditions in each reactor, with and without the algal population. The algal growth reduced the bacterial diversity and affected the bacterial community structure in the wastewater. The following in-depth analysis of the deep-sequenced amplicons showed that the algal growth selectively stimulated Sphingobacteria class members, especially the Sediminibacterium genus population, in the municipal wastewater environment.

• Journal of Microbiology
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• v.39 no.3
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• pp.195-201
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• 2001

The effect of moisture content an the reductive dechlorination of polychlorinated biphenyls and population dynamics of dechlorinating microorganisms was investigated in sediments spiked with Aroclor 1248. In sediment slurry with an overlying water layer, dechlorination ensued after a 4-week lag period and reduced the average number of chlorines per biphenyl from 3.91 to 3.15 after 48 weeks. In the sediments of reduced moisture content, however, dechlorination occurred after a lag period of 12 weeks and decreased the average number of chlorines per biphenyl to only 3.62, and the dechlorination rate was also slower. When the population size of dechlorinators, methanogens, and sulfate-reducing bacteria was determined by the most probable number techniques, however, no difference was found between the slurry and the low-moisture sediments, except for methanogens. The growth of dechlorinating populations coincided with the end of the lag period and they then increased by 3 orders of magnitude in two conditions. Specific growth rate of dechlorinators showed little difference between the slurry and the low-moisture sediments; however, growth yield was high in the sediments of reduced moisture content. The reduction of sediment moisture decreased the dechlorination rate and extent of PCBs but did not inhibit the growth of PCB dechlorinators.

• Biomedical Science Letters
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• v.27 no.4
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• pp.329-333
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• 2021

We previously identified that tumor cells genetically modified with a 4-1BBL co-stimulatory molecule had anticancer effects in a CT26 mouse colorectal tumor model. To identify the distinction between immune cells in a mouse tumor model treated with tumor cells genetically modified with 4-1BBL or β-gal, we examined the immune cells in CT26-WT, CT26-βgal, and CT26-4-1BBL tumor bearing mice 21 days after tumor cell administration. The CD8+ T cells population in mice treated with tumor cells genetically modified with 4-1BBL was significantly increased on day 21 compared to that of tumor cells genetically modified with β-gal in the spleen and tumor tissue. The CD4+ T cell population was not different between the two mice groups. The Foxp3+CD25^high CD4 T cell population decreased on day 21 in tumor tissues, but the decrease was not significant. We also found that CD8 T cells had pivotal roles in inhibiting tumor growth by treating mice with ant-CD4 and CD8 antibodies. These results suggest that tumor cells genetically modified with 4-1BBL could inhibit tumor growth by affecting on CD8 T lymphocytes.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.52-64
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• 2008

Aged sewage sludge with food waste leachate sludge or paper mill sludge was fed to earthworm (Eisenia fetida) populations and the effect of it on feeding and growth rate of earthworm population was investigated. Feeding rate of earthworm population on sewage sludge aged with food waste leachate sludge for 30 days was higher than that aged for 10 and 20 days. At 90 days after feeding, the density of earthworm population decreased regardless of aging period. And earthworm population growth to next generation was blocked by sewage sludge. The feeding rate and the density of earthworm population aged with paper mill sludge for 20 days were higher than that on sewage sludges aged for 10 and 30 days. Until 90 days after feeding, the density of earthworm population increased regardless of aging period of sewage sludge, however, since then decreased. There were comparatively higher feeding rate and growth rate of earthworm population on the sewage sludge which had been mixed with paper mill sludge and aged for 20 days, which rendered the probable pretreating method for vermicomposting sewage sludge.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.73-81
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• 2009

Population viability analysis of a Gold-spotted pond frog (Rana chosenica) population at Cheongwon-gun, Chungbuk, in South Korea was conducted and we proposed several suggestions for effective conservation and re-introduction of the species. Simulating a developed model over 1,000 times predicted that the population will exist over 30 years with a relatively low growth rate of 0.113, but with a high probability of extinction as 81.1%. Population growth and extinction probability were the most greatly depended on the rate of successful metamorphosis. In the case of outbreak of amphibian diseases such as Chytridiomycosis and Ranavirus, the population will be easily extinct within 4 years with 100% probability. In a habitat of which carrying capacity is 200, to successfully re-introduce an extinct population, it is initially needed to put 100 individuals of which 83% is males and its age structure is normal-distributed. If we additionally conducts artificial supplementation of 10% individuals every 2 years from 4 years to 10 years after initial reintroduction, the population will become a stable with 0.297 growth rate and 0.290 extinction rate. Our results are the first case of amphibian population viability analysis in Korea and could be used to develop effective conservation and re-introduction plans for endangered Gold-spotted pond frog.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.306-310
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• 2008

Characteristics of microalgal growth was investigated using anaerobic effluent from two-phase animal waste digestor as substrate. Batch experiments were carried out to investigate the effect of the initial nitrogen and phosphorus concentrations on growth of Microcystis aeruginosa, Chlorella sp. and Euglena gracilis. In 400 times diluted anaerobic effluent (TN 3 mg/L), single cell growth of the Euglena gracilis population increased twice without delay, although Chlorella sp. and Microcystis aerugenos take over 144 hours. Similar appearance with single cell growth was observed in mixed cultures. However, microalgae population did not increase under condition of 10 times diluted influent (TP 3 mg/L) in both pure and mixed cultures, which was affected by high organic and nitrogen concentration. Logistic growth model successfully fitted to determine biokinetic parameters such as ${\lambda}$: lag time, ${\mu}m$: maximal specific growth rate, A: asymptote of growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.198-203
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• 1993

The cyst of Scrippsiella trochoidea from the surface mud in Masan Bay was germinated in the incubator for the culture. This species was one of dinoflagellates responsible for the early spring bloom in the southern coastal water of Korea. The culture experiments were carried out under the various gradients of environmental factors to know their effects on the population growth of this dinoflagellate. With respect to the effects of environmental factors on the growth, it was proved that the maximum cell growth was occurred at 4,000 lux of light intensity, salinity $30\%0$ and temperature $20^{\circ}C$. When 0.25ml/ml of the filtrates of Skeletonema costatum culture medium and the supernatants of soil extracts were added to growth medium as organic growth stimulants, both materials enhanced the population growth. In the fatty acid composition of S. trochoidea, $C_{16:0}$ was the major component, and $C_{18:0},\;C_{18:1},\;C_{22:0}\;and\;C_{22:1}$ were a minor components.