• Korean Journal of Microbiology
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• v.50 no.4
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• pp.308-312
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• 2014

In this study, we conducted a next generation sequencing based microbial community analysis to investigate gut microbiota of the two commercially most available swine breeds, Yorkshire and Landrace. Bacterial 16S rRNA gene was amplified from fecal DNA using universal primer sets designed for V4 regions. Our comparison analysis of the gut microbiota of the two breeds suggested that their gut microbiota changed depending on the growth stages, while the difference between the two breeds was insignificant. However, there was a limited number of genera, the abundance of which was found to be different between the breeds. Those included the genus Xylanibacter in the Yorkshire samples, which was previously reported as a fiber digesting bacteria, likely increasing energy harvesting capacity of swine. In addition, others included opportunistic pathogens mostly found in the Yorkshire samples while the Landrace samples had significantly more prevalent Clostridium_IV species that were known to play a key role in systemic immunity of hosts. While microbial community shifts was found to be associated with growth stages, the difference between the two breeds seemed to be insignificant. However, there were several bacterial genera showing differential abundance, which may affect growth of hosts.

• Korean Journal of Environmental Agriculture
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• v.12 no.1
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• pp.59-67
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• 1993

This study was conducted to clarify the translocation and the phytotoxicity of soil treated Heptachlor (0.1ppm) and Heptachlor epoxide (0.1ppm) on Hop plants and Hansam vine. Residues in the soils and the plants were analyzed and phytotoxic patterns were investigated at the different growing stages. Photosynthetic rate and chlorophyll contents were measured. The results were summarized as follows: 1. At the second growing stage, 40 days after transplanting, severe damages by Heptachlor were observed on root of Hop. Growth rate on top and root parts of Hop was retarded from the third growing stage, 70 days after transplanting. The damages seemed to be caused by Heptachlor epoxide rather than by Heptachlor. 2. Residues of Heptachlor and Heptachlor epoxide in the plants, Hops and Hansam vine, were high at the second growing stage in comparison with those at the other stages. Residual levels in the plant parts were in order of root> stem> leaf. 3. Inhibition of photosynthetic rate was more serious in Hop plants than those in Hansam vine. The photosynthetic rate was suppressed at the second growing stage by Heptachlor epoxide and greatly reduced at the third growing stage. 4. Chlorophyll contents were not significantly changed in Hops and Hansam vine. Decreasing trends of the chlorophyll contents in both plants treated with the pesticides were similar to those of control plants.

• Development and Reproduction
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• v.5 no.2
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• pp.131-136
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• 2001

The developmental profiles of rpr, grim, dcp-1, diapl, diap2 transcripts, which were involved in programmed cell death, were analyzed using competitive RT-PCR in whole animals during Drosophila development. The fluctuation patterns of transcript levels of the apoptotic initiators(rpr and grim) were similar to those of the ecdysone titer in Drosophila life cycle. The transcript of dcp-1, which is considered as effector caspase, was expressed strong1y at early embryo and female adult stages. However, the transcript levels of anti-apoptotic factors diap1 and diap2, showed the reverse pattern comparing with those of apoptotic factors(rpr and grim). Also, the transcript levels of rpr, diap2 and dcp-1 were quantified in the salivary glands and wing discs dissected from the wandering late third instar larva. The transcript levels of rpr and diap2 were changed reversely each other in both tissues from wandering stage to puparium formation. These results suggest that the expressions of cell death related genes are regulated by the ecdysone signals during normal development.

• Journal of architectural history
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• v.11 no.2 s.30
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• pp.37-56
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• 2002

The purpose of this study is to examine the changing process of the collective housing in Korea; focusing on the alteration process of the apartment housing, which became a representative housing type in Korea, nowadays. The alteration process of the apartment housing in Korea can be divided into three stages: the introduction stage, the trial stage and the settled stage. The introduction stage is the period between 1920, when the collective-housing buildings were constructed in Korea for the first time, and the Liberation of Korea(1945). The trial stage is the period between 1945 and 1975. During this period, common housing has been constructed. And the massive apartment buildings were started to be supplied after 1975. The settled stage is the period between 1975 and the present. The main scope of this study will be the introduction and trial stages, since a lot of in-depth studies have been executed on the settled stage. The history of the collective housing of Korea starts with City Housing of Seoul, in 1921. It is guessed that this housing was to be small-sized and row-housing type. The first-built, apartment-type building, in Korea, was Mikuni Apartment House, which was constructed as a boarding room of Mikuni Company. In the introduction stage, apartment buildings were built by Japanese architects, with Japanese housing style. Most of them were planned in dormitory type, and some of them were run as tenant houses. Most of them were constructed by bricks, but sometimes by timbers. Tadami was laid in every room and inside-corridor was located in the middle of the house. Although the major style of the apartment buildings was Japanese, the Korean dwellers of those apartments has been influencing the housing type of them. In the trial stage, apartment housing has been experienced in diverse ways. With the development of building technology, floor heating system was settled in apartment housing. This improved the amenities of apartment dwelling remarkably. Although some heterogeneous characteristics still remained in the apartments of Korea, in terms of housing style, the housing style of apartments has been changed into own style of Korea, in accordance with Korean people's life style. The results of this study give us some good implications regarding contemporary housing plan: First, if the unit size of a collective housing is small, the more space could be available for community activities. Second, when planning of collective housing, more concerns should be payed on surroundings. Third, more attention should be payed about low-rise apartment housing, and more land-friendly planning would be required.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.49-58
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• 2016

Compared to planktonic bacterial populations, biofilms have distinct bacterial community structures and play important ecological roles in various aquatic environments. Despite their ecological importance in nature, bacterial community structure and its succession during biofilm development in the Antarctic marine environment have not been elucidated. In this study, the succession of bacterial community, particularly during the early stage of biofilm development, in the Antarctic marine environment was investigated by pyrosequencing of the 16S rRNA gene. Overall bacterial distribution in biofilms differed considerably from surrounding seawater. Relative abundance of Gammaproteobacteria and Bacteroidetes which accounted for 78.9-88.3% of bacterial community changed drastically during biofilm succession. Gammaproteobacteria became more abundant with proceeding succession (75.7% on day 4) and decreased to 46.1% on day 7. The relative abundance of Bacteroidetes showed opposite trend to Gammaproteobacteria, decreasing from the early days to the intermediate days and becoming more abundant in the later days. There were striking differences in the composition of major OTUs (${\geq}1%$) among samples during the early stages of biofilm formation. Gammaproteobacterial species increased until day 4, while members of Bacteroidetes, the most dominant group on day 1, decreased until day 4 and then increased again. Interestingly, Pseudoalteromonas prydzensis was predominant, accounting for up to 67.4% of the biofilm bacterial community and indicating its important roles in the biofilm development.

• Journal of Life Science
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• v.14 no.2
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• pp.331-338
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• 2004

Growth and sexual differentiation of the seaweed Porphyra pseudolinearis Ueda have been investigated monthly in the intertidal zone of the East Sea, Korea. Young blades of P. pseudolinearis appeared at the beginning of October. Carp os pores were released at the end of November immediately after carposporangia formation. Then the thalli of P. pseudolinearis were extinguished at the end of March. Young thalli were budded through the stages of conchocelis and conchospore. Thalli showed lanceolate type in shape, cordate type in holdfast, absence of microscopic spinulate process and sexual generation. Ratios of length to width in female thalli ranged from 5.6 to 7.4 at the maturation in December and slightly decreased 3.3 to 4.8 in January and 4.9 to 7.3 in December while the ratios of male thalli ranged from 4.2 to 4.8 in January. On October 12, average five individuals were obsered in a quadrate (30 cm ${\times}$ 30 cm), 238$\pm$18 individuals for the maturation stage in December and then it was reduced to 150 individuals in February and 15 individuals in March. Average sex ratios for female, male and vegetative thalli were 31.3% 46.9% and 21.9% respectively in early December, the beginning time of sex maturation. The sex ratio of female and male thalli in December 17, changed to 69.4%, 30.6% respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.298-310
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• 2021

Freshwater eel Anguilla japonica is a commercially important species in East Asia. However, given the continuously decreasing resources due to many problems as climate change, habitat destruction and overfishing, mass seed production is crucial. In particular, the eel larvae present a unique life history, spending prolonged periods in the Pacific Ocean. Therefore, finding suitable feed that lasts through the long larval stages is rather difficult. In the present study, we histologically observed the development of digestive organs for 50 days after hatching (DAH). The endogenous reserves were completely absorbed at 7 DAH, and the first exogenous feeding started thereafter. The teeth appeared at 4 DAH and dramatically changed from needle-like to broad-based types by 50 DAH. The intestine remained as straight gut until 50 DAH. The intestinal cilia appeared first at 6 DAH and their density continuously increased thereafter. Interestingly, goblet cells appeared in the intestine, but not in the esophagus, where these cells are commonly observed in other teleosts. In addition, high amounts of eosinophil substances, assumed to be zymogen granules, accumulated in the pancreas, suggesting a specific digestive strategy of this species. Overall, these observations largely update the previous reports and can be useful to improve A. japonica seed production.

• Korean Journal of Weed Science
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• v.30 no.1
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• pp.1-16
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• 2010

This study was conducted to develope identification method with major broad leaved weed seedlings. Characteristics of weed seedlings were investigated at two to four true leaf stage. Qualitative characteristics were more useful to identification of weed species than quantitative characteristics at the seedling stage. Many species were elliptic and broadly elliptic type in their cotyledon shape. Cotyledon shape of Cassia nomame and Calystegia sepium were broadly oblong. Four species were transverse broadly elliptic in their cotyledon shape. Rumex japonicus, Persicaria hydropiper, Euphorbia supina and Acalypha australis have three or more types in their cotyledon shape. Cotyledons of Vigna angularis var. nipponensis remained below ground after its germination. Many species were round in apex and were cuneate in base of cotyledon. Humulus japonicus and Polygonum aviculare were sessile in cotyledon base. The second true leaf shape of some species changed after first leaf stages. Glycine soja, V. angularis var. nipponensis and Kummerowia striata were broadly ovate, heart-shaped, orbicular or broadly obovate in their first true leaf, respectively, but the second true leaf shape of them were tripalmately compound. Aeschynomene indica and Cassia nomame were paripinnately compound leaf in their first and second true leaves. Margin of true leaves were entire in many species but six species including Xanthium occidentale were dentate in their true leaf margins. Margin of Euphorbia supina was entire in first true leaf and dentate in second true leaf. Margin of Chenopodium album and C. serotinum were entire in their first true leaf stage and erose in their second true leaf stage. The key for weed seedling identification of major weed species were made based on quantitative and qualitative morphological characteristics.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.121-132
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• 2005

We investigated the reproductive cycle with gonad developmental phases of Sinonovacula constricta by histological observations, and seasonal changes in biochemical component of the adductor muscle, visceral mass, foot muscle and mantle were studied by biochemical analysis, from January to December, 2004. The reproductive cycle of this species can be classifed into five successive stages: early active stage (March to May), late active stage (May to July), ripe stage (July to September), partially spawned stage (August to October) and spentfinactive stage (October to March). Total protein content was the highest in the following order: adductor muscle, visceral mass, foot muscle, and mantle. Except for mantle, it was generally higher during the ripe and spawning stages, while lower during the spent/inactive stage. There were positive correlations in total protein contents among adductor muscle, foot muscle, and visceral mass. However, the correlations were not statistically significant. Total lipid content was the highest in the visceral mass; it was more than 5 or 6-fold higher than those in the adductor muscle, foot muscle, or mantle. The monthly change was also most dynamic in the visceral mass. It first Increased during the early active stage (March to May), decreased during late active stage (May to July), and then increased again rapidly during the spawning stage (September). There were a strong negative correlation in total lipid contents between foot muscle and adductor muscle (r = -0.634, p = 0.027), and a strong positive correlation between adductor muscle and mantle (r = 0.665, p = 0.018). Glycogen contents showed more or less similar pattern to total lipid contents in the adductor muscle, foot muscle, and visceral mass. It was higher during the early active and spawning stages, while lower during the late active and spent/inactive stages. There was no statistically significant correlation in glycogen contents among different tissues. Especially, total lipid content showed a negative correlationship between the foot muscle, adductor muscle, visceral mass and mantle. Therefore, these results indicate that the nutrient content of the foot muscle, adductor muscle, viseral mass and mantle changed in response to gonadal energy needs.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.687-696
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• 2015

Black mini tomato 'Hei-G' fruits were harvested at different stages of maturity (immature-mature green and mature-black red) and stored at different temperatures (8, 12, and $20^{\circ}C$) to investigate the quality and lycopene content during storage. Weight loss increased dramatically at higher temperature for both harvesting stages without significant differences. Firmness of immature fruits decreased below the initial level of mature fruit (8.1N) after 5, 8, and 19 days storage, when they were stored at 20, 12, and $8^{\circ}C$, respectively. Soluble solid contents of mature fruit increased at initial storage, and were higher as compared to immature fruits before deterioration at each storage temperature. Decrease in titratable acid of mature fruits depended on storage time and temperature. However, titratable acid of immature fruits showed little change during storage, and so it did not affect flavor. Hunter a value changed greatly in immature fruit stored at high temperature. Unlike ripe tomatoes, there was no significant difference in black tomato Hunter b values of immature and mature fruit at initial and 12 days storage. However, immature fruits stored at $8^{\circ}C$ did not reach full maturity and color development and ripening. High storage temperature increased lycopene production while low storage temperature blocked lycopene development. Shelf life of the immature fruits, which was evaluated by elapsed days to conventional mature stage, was 12 and 15 days when they were stored at 20 and $12^{\circ}C$, respectively. The optimum storage temperature to maintain the quality and lycopene content of mature fruits was $12^{\circ}C$. Moreover, the shelf life of mature fruits stored at $20^{\circ}C$ could reach up to 5 days.