• Development and Reproduction
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• v.10 no.1
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• pp.63-73
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• 2006

This study aimed to find out suitable culture conditions for the differentiation of human amniotic membrane-derived stem cells(HAM) into hepatocyte-like cells. Almost homogenous population of fibroblast-like cells was successfully isolated from the amniotic membrane. In comparison to the non-coated plates and in the absence of insulin/transferrin/selenium(ITS), HAM cultured on the fibronectin-coated plates and in the presence of ITS showed the more intense immunocytochemical staining against the albumin. Addition of both fibroblast growth factor(FGF)-1 and -2 to the differentiation medium gave stronger staining compared to the treatment with FGF-1 or -2 alone. Periodic acid Schiff's base staining of glycogen and morphological turnover of fibroblast-like appearance of HAM into round shape matched the results of immunocytochemical studies. When the efficiency of two-step culture method was examined on the differentiation of HAM into hepatocyte-like cells, all of the results of immunocytochemical staining, periodic acid Schiff's staining and morphological change exhibited effective hepatic differentiation of HAM compared to the continuous culture method. Immunoblot analyses of HAM- conditioned media against the albumin showed that the culture of HAM in the presence of both ITS and fibronectin always gave a stronger staining intensity than those in the absence of them, and that the addition of ether mixture of FGF-4 and either FGF-2 or transforming growth $factor(TGF)-{\alpha}$ to the culture medium significantly enhanced the albumin secretion by HAM. Based on these observations, it is suggested that HAM could differentiate into hepatocyte-like cells under a culture condition consisting of fibronectin and ITS, and addition of FGF-4 with either one of FGF-2 or $TGF-{\alpha}$ could enhance the hepatic differentiation of HAM.

• Korean Journal of Poultry Science
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• v.8 no.1
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• pp.1-5
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• 1981

In trying to predict the effect of genetics on the broiler in the year 2000, this is a relatively short period of time as far as broiler genetics in concerned. Modern broiler genetics started around 1945 and tremendous gains when made in past 35 years. Futher improvements on broiler will depend on the evolution and revolution: 1. Evolution: (1) Growth rate has been made 4-5% per year. (2) Feed conversion has improved approximately 1% per year. (3) Abdominal fat is becoming a major complaint in broiler. (4) Because of the changing life-style, broiler meat sales in the future will be more and more in cut-up form. (5) Breeding for stress resistance and selection for docile temperament can be important in order to funker improve fled efficiency. (6) In female parent stock, reproduction characteristics are in many can negatively correlated with the desired broiler traits. (7) Egg production and hatchability in moot commercial parent nod m at a fairly high level. (8) In male parent stock, the heavier and mon super-meat-type male lines are desired to Product better broilers. 2. Revolution: Trying to forecast revolutionary change in broiler genetics is highly speculative, as sudden change are aften unpredictable. (1) Species hybridization, such as a turkey-chicken cross (2) Biochemical tools, such as blood typing. (3) Mutation breeding by radiation or chemical mutagentia. (4) Broiler breeding would be to change the phenotypic appearance by single gene, such as naked, wingless. (5) Changes in production techniques. such as growing in cage or growing in filtered air positive pressure houses.

• Development and Reproduction
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• v.12 no.1
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• pp.87-95
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• 2008

Neural stem/precursor derived from pluripotent human embryonic stem cells (hESCs) has considerable therapeutic potential due to their ability to generate various neural cells which can be used in cell-replacement therapies for neurodegenerative diseases. However, production of neural cells from hESCs remains technically very difficult. Understanding neural-tube like rosette characteristic neural precursor cells from hESCs may provide useful information to increase the efficiency of hESC neural differentiation. Generally, neural rosettes were derived from differentiating hEBs in attached culture system, however this is time-consuming and complicated. Here, we examined if neural rosettes could be formed in suspension culture system by bypassing attachment requirement. First, we tested whether the size of hESC clumps affected the formation of human embryonic bodies (hEBs) and neural differentiation. We confirmed that hEBs derived from $500{\times}500\;{\mu}m$ square sized hESC clumps were effectively differentiated into neural lineage than those of the other sizes. To induce the rosette formation, regular size hEBs were derived by incubation of hESC clumps($500{\times}500\;{\mu}m$) in EB medium for 1 wk in a suspended condition on low attachment culture dish and further incubated for additional $1{\sim}2$ wks in neuroectodermal sphere(NES)-culture medium. We observed the neural tube-like rosette structure from hEBs after $7{\sim}10$ days of differentiation. Their identity as a neural precursor cells was assessed by measuring their expressions of neural precursor markers(Vimentin, Nestin, MSI1, MSI2, Prominin-1, Pax6, Sox1, N-cadherin, Otx2, and Tuj1) by RT-PCR and immunofluorescence staining. We also confirmed that neural rosettes could be terminally differentiated into mature neural cell types by additional incubation for $2{\sim}6$ wks with NES medium without growth factors. Neuronal(Tuj1, MAP2, GABA) and glial($S100{\beta}$ and GFAP) markers were highly expressed after $2{\sim}3$ and 4 wks of incubation, respectively. Expression of oligodendrocyte markers O1 and CNPase was significantly increased after $5{\sim}6$ wks of incubation. Our results demonstrate that rosette forming neural precursor cells could be successfully derived from suspension culture system and that will not only help us understand the neural differentiation process of hESCs but also simplify the derivation process of neural precursors from hESCs.

• Korean journal of communication and information
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• v.51
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• pp.26-46
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• 2010

This study interprets Cheong-gye-cheon restoration as a process of space production during expansion of capitalism, and performs discourse analysis in order to find out that how media discourse has been related to the production of Cheong-gye-cheon space in each period of historical changes. This paper is particularly concentrating on discovering regulation in discourse which connects people's experiences and perception towards certain ways in the relationship between newly producted space and media discourse. This paper construes the period of 1960s as a process which pre-modern bodies and facilities were changed into modern and urban 'daily life' by practicing a space which splitted in a concept of time efficiency. In 1980s, media represented the facilities which had been constructed at the Cheong-gye-cheon space as a 'disqualified facilities for a center of the city'. This is because, tertiary industries were emerged at the 'Gang-nam' in this period which widen the gap of finance between 'Gang-nam' and 'Gang-Buk'. The government wanted to redevelop this space in order to function accumulating capital efficiently. Therefore shop owners nearby Cheong-gye-cheon were forced to move out. The discourse, 'disqualified facilities for a center of the city', implicates this process. The media discourse in the 2000s produced the 'myth' through the 'signifier' such as artificially flowing water, fine scenery, historical but artificial structure and etc.. However, people can experience symbols of the artificial structures which leads people to the luxurious restaurants, coffee shops, and etc.. Naturally, the spectacles produced by media direct people to the homogeneous pattern of consume. This phenomena can be explained as a process which people practice, intentionally or non-intentionally, the capitalistic mode of production which changed from a period of production to a period of consumption.

• Reproductive and Developmental Biology
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• v.32 no.3
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• pp.153-158
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• 2008

Tissue-specific and temporal regulation of milk protein gene expression is advantageous when creating transgenic animal that produces foreign protein into milk. Gene expression, i.e. protein production, is regulated not only by promoter strength but also mRNA stability. Especially, poly A tail length by polyadenylation affects in vivo and in vitro mRNA stability and translation efficiency of the target gene. In the present study, nucleotide sequence of 3'-UTR was analyzed to evaluate the effects of mRNA stability on the target gene expression. Based on the poly A signal of 3' -untranslated region (UTR), nucleotide sequences of putative cytoplasmic polyadenylation elements (CPEs) and downstream elements (DSEs: U-rich, G-rich, GU-rich) were analyzed and used to construct 15 luciferase reporter vectors. Each vector was transfected to HC11 and porcine mammary gland cell (PMGC) and measured for dual luciferase expression levels after 48 hours of incubation. Luciferase expression was significantly higher in construct #6 (with CPE 2, 3 and DSE 1 of exon 9) and #11 (with CPE 2, 3 and DSE 1, 2 and 3 of exon 9) than construct #1 in the PMGC. These results suggest that expression of target genes in PMGC may be effectively expressed by using the construct #6 and #11 on production of transgenic pig.

• Reproductive and Developmental Biology
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• v.31 no.3
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• pp.199-205
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• 2007

The present study was carried out to assess the effect of superovulation response and efficiency of embryo production induced with injection of FSH dissolved in polyethylene glycol (PEG) in Hanwoo. Eighty-eight cows were divided into four groups. In group 1, cattle were intramuscularly treated with twice-daily administration of 50mg FSH for 4 days. Group 2 and 3 were subcutaneously single injection of 400mg and 200mg FSH dissolved in 30% PEG, respectively. Group 4 were subcutaneously single injection of 200 mg FSH dissolved in 30% PEG at 7 day after CIDR insertion. The number of corpus luteum (CL) in group 2 resulted in significantly (p<0.05) higher compared to group 1, 3 and 4 (18.5 vs. 11.2, 13.1 and 13.9, respectively). However, the number of total ova $(7.9{\sim}10.4)$, transferable embryos $(3.7{\sim}4.7)$, degenerate embryos $(1.9{\sim}3.5)$ and unfertilized ova $(1.8{\sim}2.7)$ did not differ among treatment groups. No difference was observed in pregnancy rate after transferring the recovered embryos among groups $(36.0{\sim}50.0%)$. In addition, blood progesterone concentrations at embryo recovery did not differ among all groups. In conclusion, although no differences were observed in the number of total ova, transferable embryos and pregnancy rate after transfer, a single injection of reduced dose of FSH (200mg FSH) at 7 day after CIDR insertion is more practical for superovulation treatments than frequent injection because of reduction of stress in Hanwoo and decreases of cost and laber.

• Journal of Animal Environmental Science
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• v.17 no.1
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• pp.39-48
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• 2011

The present survey was conducted to provide basic information on automatic milking system (AMS) in relation to purchase motive, milk yield and quality, customer satisfaction, difficulties of operation and customer suggestions, etc. Purchase motives of AMS were insufficient labor (44%), planning of dairy experience farm (25%), better performance of high yield cows (19%) and others (6%), respectively. Average cow performance after using AMS was 30.9l/d for milk yield, 3.9% for milk fat, 9,100/ml for bacterial counts. Sixty-eight percentage of respondents were very positive in response to AMS use for their successors but 18% were negative. The AMS operators were owner (44%), successor (44%), wife (6%) and company worker (6%), respectively. The most difficulty (31%) in using AMS was operating the system and complicated program manual. The rate of response to system error and breakdown was 25%. The reasons for culling cow after using AMS were mastitis (28%), reproduction failure (19%), incorrect teat placement (12%), metabolic disease (7%) and others (14%), respectively. Fifty-six percentages of the respondents made AMS maintenance contract and 44% did not. Average annual cost of the maintenance contract was 6,580,000 won. Average score for AMS satisfaction measurement (1 to 5 range) was 3.2 with decrease of labor cost 3.7, company A/S 3.6, increase of milk yield 3.2 and decrease of somatic cell count 2.8, respectively. Suggestions for the higher efficiency in using AMS were selecting cows with correct udder shape and teat placement, proper environment, capital and land, and attitude for continuous observation. Systematic consulting was highly required for AMS companies followed by low cost for AMS setup and systematization of A/S.

• Development and Reproduction
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• v.5 no.1
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• pp.47-52
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• 2001

Predetermination of sex in livestock of offpring is in great demand and is of critical importance to providing for the most efficient production of the animal ariculture. Such a sexing techlology would also enhance the economy of conventional artificial insemination(AI) and aid the porcine industry. The purpose of this study was to evaluate the efficiency of enriching X-bearing porcine sperm using discontinuous percoll gradients and PCR mefhod. Semen was collected from mature boars of proven fertility center (AI center KimHae). Sperm was leaded on the isotonic discontinuous percoll gradient and then it was centrifuged at 120 ${\times}$ g for 20 minutes. After centrifugation, sperm included in each fraction were recovered (7${\times}$10$^6$ sperms/ml) and then sperm genomic DNA was extractedfor the PCR. SRY gene was used to evaluate the ratio between X and Y sperm in the separated fractions. Ju viro ffrtilization wascarried out by adding the unseparated sperm (control) or separated (experimental poop) to the matured oocytes in TCM-199. Embryos for sex determination were obtained at 2 cell stage and then was used for SRY gene amplification. After centrifugation of discontinuous percoll gradient, the most motile sperm was obtained at 95% fiaction (94.4% ${\pm}$ 5.1%, p < 0.01). The PCR analysis evaluated that 30%, 50% and 65% fractions were Y sperm rich, whereas 80% and 95% fractions were X sperm rich. PCR analysis with each porcineembryo showed that 33.3% of control and 66.7% of experimental group were determined as female embryos. In conclusion, in vitro matured oocytes inseminated with sperms (95% fraction) prepared by percoll gradient centrifugation showed high fertilization rates and female embryos than control sperms.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.485-496
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• 2022

Modern agriculture is being transformed into smart agriculture to maximize production efficiency along with changes in the 4th industrial revolution. However, rural areas in Korea are facing challenges of aging, low fertility, and population outflow, making it difficult to transition to smart agriculture. Among ICT technologies, simulation allows users to observe or experience the results of their choices through imitation or reproduction of reality. The combination of the three-dimension (3D) model and the greenhouse simulator enable a 3D experience by virtual greenhouse for fruits and vegetable cultivation. At the same time, it is possible to visualize the greenhouse under various cultivation or climate conditions. The objective of this study is to apply the greenhouse climate management model for simulation development that can visually see the state of the greenhouse environment under various micrometeorological properties. The numerical solution with the mathematical model provided a dynamic change in the greenhouse environment for a particular greenhouse design. Light intensity, crop transpiration, heating load, ventilation rate, the optimal amount of CO₂ enrichment, and daily light integral were calculated with the simulation. The results of this study are being built so that users can be linked through a web page, and software will be designed to reflect the characteristics of cladding materials and greenhouses, cultivation types, and the condition of environmental control facilities for customized environmental control. In addition, environmental information obtained from external meteorological data, as well as recommended standards and set points for each growth stage based on experiments and research, will be provided as optimal environmental factors. This simulation can help growers, students, and researchers to understand the ICT technologies and the changes in the greenhouse microclimate according to the growing conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.371-384
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• 1982

Highly cold tolerant varieties are requested not only at high latitute cool area but also tropical high elevated areas, and the required tolerance is different from location to location. IRRI identified 6 different types of cold tolerance required in the world for breeding purpose; a) Hokkaido type, b) Suweon type, c) Taipei 1st season type, d) Taipei 2nd season type, e) Tropical alpine type and, f) Bangladesh type. The cold tolerance requested in Korea is more eargent in Tongil group cultivars and their required tolerance is the one such as the physiological activities at low temperature are as active as in Japonica group cultivars at least during young seedling stage and reproduction stage. With conventional Japonica cultivars, such cold tolerant characters are requested as short growth duration but stable basic vegetative growth, less sensitive to high temperature and less prolonged growth duration at low temperature. The methods screening for cold tolerance were developed rapidly after the Tongil cultivar was reliesed. The facilities of screening for cold tolerance, such as, low temperature incubator, cold water tank, growth cabinet, phytotron, cold water nursery in Chuncheon, breeding nursery located in Jinbu, Unbong and Youngduk, are well established. Foreign facilities such as, cold water tank with the rapid generation advancement facilities, cold nurseries located in Banaue, Kathmandu and Kashimir may be available for the screening of some limitted breeding materials. For the reference, screening methods applied at different growth stages in Japan are introduced. The component characters of cold tolerance are not well identified, but the varietal differences in a) germinability, b) young seedling growth, c) rooting, d) tillering, e) discolation, f) nutrition uptake, g) photosynthesis rate, h) delay in heading, i) pollen sterility, and j) grain fertility at low temperature are reported to be distinguishable. Relationships among those traits are not consistent. Reported studies on the inheritance of cold tolerance are summarized. Four or more genes are controlling low temperature germinability, one or several genes are controlling seedling tolerance, and four or more genes are responsible for the pollen fertility of the rice treated with cold air or grown in the cold water nursery. But most of those data indicate that the results may come out in different way if those were tested at different temperature. Many cold tolerant parents among Japonicas, Indicas and Javanicas were identified as the results of the improvement of cold tolerance screening techniques and IRTP efforts and they are ready to be utilized. Considering a) diversification of germ plasm, b) integration of resistances to diseases and insects, c) identification of adaptability of recommending cultivars and, d) systematic control of recommending cultivars, breeding strategies for short term and long term are suggested. For short term, efforts will be concentrated mainly to the conventional cultivar group. Domestic cultivars will be used as foundation stock and ecologically different foreign introductions such as from Hokkaido, China or from Taiwan, will be used as cross parents for the adjustment of growth durations and synthsize the prototype of tolerances. While at the other side, extreme early waxy Japonicas will be crossed with the Indica parents which are identified for their resistances to the diseases and insects. Through the back corsses to waxy Japonicas, those Indica resistances will be transfered to the Japonicas and these will be utilized to the crosses for the improvement of resistances of prototype. For the long term, efforts will be payed to synthsize all the available tolerances identified any from Japonicas, Indicas and Javanicas to diversify the germ plasm. The tolerant cultivars newly synthsized, should be stable and affected minimum. to the low temperature at all the growing stages. The resistances to the diseases and insects should be integrated also. The rapid generation advancement, pollen culture and international cooperations were emphasized to maximize the breeding efficiency.