• Journal of Animal Science and Technology
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• v.66 no.2
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• pp.398-411
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• 2024

Upregulation of the nutritional value of feed is the major target of various studies in the livestock industry, and dietary enzyme supplementation could aid in digesting the nondegrading nutrients of grains in feed ingredients. Dried distillers' grains with solubles (DDGS) is a byproduct of the fermentation process in the beverage industry and can be used as a large supply source of fiber in feed. Therefore, we conducted an experiment with male broiler chickens to investigate the effect of various types of enzymes on DDGS and compare the efficacy of single enzyme and multienzyme complexes on growth performance and gut environments in broiler chickens. We used 420 1-day-old broiler chickens (Ross 308), and they were allotted into 4 dietary treatments with seven replications (CON, corn-soybean meal [SBM] diet; NC, DDGS supplemented diet; SE, 0.05 % of mannanase supplemented DDGS-based diet; MC, 0.10% of multienzyme complex (mannanase and xylanase, glucanase) supplemented DDGS-based diet. The dietary exogenous enzyme in the DDGS-supplemented diet could improve growth performance as much as the growth of the control group, and digestibility of dry matter, crude protein, and gross energy were significantly increased by enzyme addition in groups of chicks fed DDGS-supplementation diet. Moreover, the populations of pathogenic bacteria, coliforms, and Bacteroidetes were significantly decreased by enzyme supplementation, which might lead to improved gut mucus-secreting cells and inflammatory cytokines in the jejunum. Collectively, dietary single enzyme and multienzyme complexes could improve gut environments, including intestinal immune responses and gut microbial population, and lead to improvement of growth performance in broiler chickens.

• International Journal of Stem Cells
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• v.16 no.1
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• pp.1-15
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• 2023

Liver organoids have gained much attention in recent years for their potential applications to liver disease modeling and pharmacologic drug screening. Liver organoids produced in vitro reflect some aspects of the in vivo physiological and pathological conditions of the liver. However, the generation of liver organoids with perfusable luminal vasculature remains a major challenge, hindering precise and effective modeling of liver diseases. Furthermore, vascularization is required for large organoids or assembloids to closely mimic the complexity of tissue architecture without cell death in the core region. A few studies have successfully generated liver organoids with endothelial cell networks, but most of these vascular networks produced luminal structures after being transplanted into tissues of host animals. Therefore, formation of luminal vasculature is an unmet need to overcome the limitation of liver organoids as an in vitro model investigating different acute and chronic liver diseases. Here, we provide an overview of the unique features of hepatic vasculature under pathophysiological conditions and summarize the biochemical and biophysical cues that drive vasculogenesis and angiogenesis in vitro. We also highlight recent progress in generating vascularized liver organoids in vitro and discuss potential strategies that may enable the generation of perfusable luminal vasculature in liver organoids.

• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.392-401
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• 2008

The vertical changes (upper layer: 0$\sim$0.5 m, middle layer: 4$\sim$5 m and lower layer: 8$\sim$10 m) of the limnological variables, zooplankton dynamics and community filtration rate on the phytoplankton were evaluated monthly intervals from November 2004 to June 2007 at the artificiallake (Okjeong Lake). During the study, the annual mean of water temperatures were 15.2$\pm$7.8$^{\circ}C$ (upper layer), 14.5$\pm$7.4$^{\circ}C$ (middle layer) and 13.0$\pm$6.2$^{\circ}C$ (lower layer), respectively (n=30). The vertical variations of most limnological parameters (DO, pH, conductivity and turbidity) were fairly similar, except for chl.-${\alpha}$ concentration. Annual mean of chl.-${\alpha}$ concentration was highest at the upper layer (21.4 ${\mu}g$ L$^{-1}$), while annual means of concentrations were low at the middle layer and lower layer (4.3 ${\mu}g$ L$^{-1}$ and 3.5 ${\mu}g$ L$^{-1}$, respectively). Annual mean of Secchi depth was 261 cm (n=30). A total 45 species of zooplankton were identified (28 rotifers, 12 cladocerans and 5 copepods) during the study. The mean abundance of rotifers was highest (124$\pm$232 ind. L$^{-1}$, n =90) and that of cladocerans and copepods were relatively low (22$\pm$56 ind. L$^{-1}$ and 13$\pm$30 ind. L$^{-1}$) in the whole layer. Total zooplankton abundance increased from late spring to summer, and then declined and remained low throughout the winter. The annual mean of total zooplankton filtration rate for phytoplankton at the lower layer was much higher than that of both layers (upper layer: 44.4$\pm$107.8, middle layer: 95.1$\pm$436.4 and lower layer: 158.2$\pm$436.4 mL L$^{-1}$ day$^{-1}$). Among the major zooplankton community, relative community filtration rate (RCFR, %) of copepods for phytoplankton (50.2$\sim$54.8%) was much higher than that of cladocerans (27.7$\sim$36.3%) and rotifers (8$\sim$17.6%). The seasonal variation of RCFRs of major zooplankton community was observed. The RCFRs of rotifers were high in winter (44.6%, n=9), while the RCFRs of cladocerans were high in summer (58.0%, n=7). In spring and fall, the RCFRs of copepods were high in the whole layer (spring: 67.4%, n=9; fall: 74.4%, n=5).

• Korean Journal of Plant Taxonomy
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• v.46 no.2
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• pp.213-246
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• 2016

Algific talus slopes tend to occur on steep north-facing slopes with bedrock that retains ice and emits cold air throughout the growing season. Algific talus slopes provide a suitable microclimate for disjunct or relict populations of northern plant species at low altitude habitats in temperate zones. The purpose of this study is to suggest a strategy for the comprehensive conservation of the vegetation of algific talus slopes through studies of the floristics and plant species compositions and threat factors at present and in the future of 15 major algific talus slopes in Korea. As a result, the vascular plants surveyed on 15 major algific talus slopes were recorded, with a total of 587 taxa, 109 families, 323 genera, 531 species, 7 subspecies, 47 varieties 1 form and 1 hybrid. Of them, endemic plants numbered 26 taxa, and threatened species according to the IUCN valuation basis numbered 8 taxa. Fourth (IV) and fifth (V) degree indicator species as specified by floristic subregions numbered 31 taxa. Peculiarly, several subalpine-native plant species, in this case Cystopteris fragilis, Gymnocarpium dryopteris, Huperzia selago, Rosa koreana, Vaccinium vitis-idaea and Woodsia hancockii, were distributed on algific talus slopes at 100-600 m above sea level. Numerous and diverse biological resources native to algific talus slopes in Korea have been consistently disturbed or damaged by human activities without some form of protection. An all-taxa biodiversity inventory should be surveyed to provide more information about all biological species living on algific talus slopes. In addition, conservation strategies to ensure biodiversity and effective management of algific talus slopes are discussed in detail.

• Journal of Life Science
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• v.20 no.2
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• pp.237-244
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• 2010

Five mold strains - Mucor racemousus, Rhizopus oryzae, Aspergillus oryzae, Aspergillus kawachii, and Monascus purpureus - were used for the fermentation of both freeze-dried and air-dried silkworm powders. The concentrations of proteins and minerals, electrophoretical protein patterns, fatty acid composition and the activities of fibrinolytic and antioxidation with freeze-dried silkworm (FDSW) or air-dried silkworm powders (ADSW) fermented by the five molds were investigated. The concentrations of major minerals in fermented FDSW and ADSW powders were K by 72.0-76.3 and 77.1-78.9 ppm, Mg by 29.6-49.7 and 44.3-58.7 ppm, Ca by 1.9-14.9 and 9.8-21.6 ppm and Zn by 0.64-0.70 and 4.17-4.52 ppm, respectively. Major fatty acids in fermented FDSW and ADSW powders were linolenic acid, oleic acid, and palmitic acid. There were slightly varietal differences in electrophoretical protein patterns when total protein patterns of fermented FDSW and ADSW powders were analyzed by native-and SDS-polyacrylamide gel electrophoresis (PAGE). DPPH radical scavenging activity was slightly stronger in fermented ADSW powders than that in fermented FDSW. Fibriolytic activity was only detected in the FDSW fermented by Aspergillus kawachi and Monascus purpureus. These results may provide the basic data to understand the biological activities and chemical characteristics of silkworm fermented by mold, which can be used for the development of functional foods.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.217-231
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• 2018

Planktonic ciliates play an important role in the food web of marine ecosystem as well as a bio-indicator for invasive species from ballast waters or from changing flow of ocean currents due to climate changes. This study was carried out to find some evidences for introduction of such invasive species using ciliate plankton in four major international ports of Korea. We surveyed the seasonal species composition of planktonic ciliate to find out the evidence for the invasive species at Busan, Ulsan, Gwangyang and Incheon ports from February 2007 to November 2008. A total of 45 ciliates species, belonging to 15 genera, were identified during the study period: 33 species occurred at Busan, 31 at Gwangyang, 30 at Ulsan, 18 at Incheon. The abundance of naked ciliates ranged from 566 to $65,151cells\;L^{-1}$ and that of tintinnids 10 to $5,973cells\;L^{-1}$. Based on vector species of ciliates reported from Coos Bay in Oregon, 13 vector species of tinitinnids were identified as follows, Eutintinnus lususundae, E. tubulosus, Favella ehrenbergii, F. taraikaensis, Helicostomella subulata, Stenosemella nivalis, Tintinnopsis ampla, T. beroidea, T. cylindrica, T. directa, T. lohmanni, T. radix, T. rapa. All vector species occurred at Gwangyang port. Most tintinnids were mainly neritic species throughout the survey, while warm water species occurred only in short period at Busan, Ulsan and Gwangyang ports that might be affected seasonally by Tsushima warm current.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.463-472
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• 1998

Biotechnology is the process of using biological system for the production of materials. Genetic engineering, a subset of biotechnology, is the process of altering biological systems by the purposeful manipulation of DNA It is a new field in biology and no topic in biology is more likely to impact our personal lives and is therefore more worthy of our attention and understanding. The purpose of this study was to investigate students' understanding of the concepts of biotechnology, and a test tool which is made up of 20 basic questions was developed for the study. The subject of this study was high school students and the sample size was 486. In order to find out the source of students' misunderstanding, we also analysed high school textbooks and teachers were given the same tool applied to students. Two-way ANOVA was used for the analysis. Major findings of this study are as following; 1. Mean score of students was 41, and there was a significant difference between the scores of boys and girls(p<0.05). Female students scored higher than male students. The variables "region" and "major" had no significant influence. 2. Students' the most misunderstood concepts were "monoclonal antibody" and "gene cloning". Many students thought that a plamid DNA originally has a useful DNA in it, which is apparently wrong. 3. Mean score of teachers was 82, and the variabes of gender and career did not have statistically significant influence on the result(p>0.05). 4. Teachers got the lowest scores on the concepts of "gene therapy", "the accomplishment of biotechnology in agriculture and medicine", and "plasmid DNA". The results of item analysis implied that teachers' misunderstanding might be a part of the sources of students' misunderstaning. 5. Out of 18 basic concepts selected in the study, only 10 concepts were explained well enough in most textbooks. The results of item analysis indicated that textbooks also could be a part of the source of students' misunderstanding.

• The Korean Journal of Mycology
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• v.26 no.3 s.86
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• pp.373-379
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• 1998

Rhizoctonia solani [Thanatephorus cucumeris (frank) Donk], one of the major soil-borne plant pathogens with world-wide distribution, can cause great damages on various crops. In Korea, sheath blight on rice caused by this pathogen is the major concern, and active studies on this pathogen have been performed. However, most of these studies were concerned with pathogenicity of the isolates instead of molecular analyses of different AGs of R. solani. Therefore, in this study, thirty isolates of Rhizoctonia solani collected from various sources were used for the analyses of genetic relationships among themselves and for the rapid anastomosis grouping with RAPD method. As a result, thirty isolates of known and unknown AGs were grouped into five subgroups and each group included AG-1, AG-2, AG-3, AG-4, and AG-5. RS-1 isolate was found to be closely related to AG-5. Isolates RS-4, RS-14, RS-17, and RS-16 were found to be closely related to AG-2-2(III B). Isolate RS-13 was closely related to AG-4, isolates RS-8 and RS-10 were closely related to AG-1(I B), and isolates RS-7 and RS-21 were closely related to AG-2-2(IV). Isolate RS-19 was closely related to AG-1(I C), and isolates RS-3, RS-5, RS-18, RS-6, and RS-15 were found to be closely related to AG-1.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.525-537
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• 2018

The Korean coast is divided into the West Korea Coastal zone (WKC), the South Coastal zone of Korea (SCK), the East Korea Coastal zone (EKC), and Jeju Coastal zone of Korea (JCK). Each coastal zone has different marine environment characteristics. This study analyzed zooplankton data of KOEM (Korea Environment Management Corporation) collected in the Korean coastal waters the spring and summer of 2015 and 2016. In spring, water temperature was lowest in the JCK, and gradually increased in the order of EKC, SCK, and WKC, while in summer lowest in WKC and increased in the order of EKC, SCK, and JCK. Salinity was lowest in WKC which had many rivers flowing inland, and increased in the order of SCK, EKC and JCK in spring. In summer it was lowest in JCK and increased toward WKC, SCK, and EKC. In summer, Chlorophyll-a concentrations were generally low, but was lowest in JCK in spring. In the study area, a total of 77 species occurred, of which 50 species did in spring and 65 species in summer. The number of species was lowest in JCK and highest in SCK in spring and summer, respectively. Paracalanus parvus s. l. was the most dominant species or the second dominant species in Korean coastal areas in spring, but it was predominant in summer. In addition, in spring Acartia hongi, Calanus sinicus, Oithona similis were predominant in WKC, Oithona similis and Corycaeus affinis in SCK, O. similis and Corycaeus sp. in EKC, C. affinis and O. setigera in JCK. In summer Corycaeus spp., O. similis, A. hongi, Tortanus forcipatus were predominant in WKC, C. affinis, Pseudodiaptomus marinus in SCK, O. similis, A. omorii, Corycaeus sp. in EKC, and A. steueri, A. pacifica, Oithona sp., C. sinicus in JCK. The copepod community in the Korean coastal areas were classified into four areas, WKC-western SCK, eastern SCK, EKC and JCK according to differences in environmental factors such as water temperature, salinity, Chl-a concentration, and suspended matter concentration of each coastal area.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.148-156
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• 2022

Ecological occupation in irrigation ponds is a well-acknowledged fact that is essential for biodiversity conservation in agricultural ecosystems. However, there are few studies on the ecological functions and relationship between a paddy field and irrigation using macroinvertebrates in an environmentally friendly paddy field. The objective of this study is to identify the community and distribution characteristics of macroinvertebrates in an agricultural paddy field and irrigation pond ecosystems, and to provide basic data on the ecological function of an environmentally friendly paddy field. Macroinvertebrate sampling was conducted from May to September in an agricultural paddy field and irrigation pond in an environment-friendly paddy field in Boryeong city. We conducted a study to identify the distribution characteristics using macroinvertebrate species analysis, such as Functional Feeding Groups (FFGs), Habitat Oriented Groups (HOGs), rarefaction curve, and a two-way dendrogram. A total of 37 species of macroinvertebrates in 28 families, 13 orders were collected study during the period of the investigation. Dominant taxa of macroinvertebrates included Coleoptera, Hemiptera, and Odonata. In terms of FFGs, predators and gathering collectors accounted for approximately 70%, in relation to HOGs, and climbers and swimmers occupied more than 50% from both the paddy field and irrigation pond. With respect to the rarefaction curve, the irrigation pond (July) was high as E (S, 141)=18 species, while the paddy field (May) was comparatively low as E (S, 141)=9 species. In conclusion, our results revealed that macroinvertebrates, such as Notonecta triguttata, Peltodytes intermedius, Appasus major, Laccotrephes japonensis, Appasus japonicus, Sigara substriata, Enochrus simulans, and Sternolophus rufipes, were used as a habitat and spawning ground in both paddy field and irrigation pond. The irrigation pond appears to be a very important spawning ground for macroinvertebrates.