• Korean Journal of Veterinary Service
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• v.42 no.2
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• pp.93-112
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• 2019

Calf diarrhea is a common disease in young claves and is still a major cause of productivity and economic loss in livestock farms. Fecal samples from Korean native cattle (n=100) with diarrhea from 64 farms in Gwangju area, Korea from september 2017 to December 2018 were examined for shedding of important protozoan parasitic, viral and bacterial pathogens using culture, rapid test kit and PCR methods. Of 57 (89.1%) of the 64 Korean native cattle farms examined had samples infected with at least one of the investigated pathogens. Among 100 fecal samples, 88 samples were positive for at least one the twelve pathogens and 51 samples were simultaneously positive for two or more pathogens by culture and PCR assay. Bovine group A rotavirus (BRV) was the most common pathogen, found in 43/100 (43.0%) samples on 32/64 (50.0%) farms. Subsequently, kobuvirus (30.0%), pathogenic E. coli (29.0%), bovine parvovirus (17.0%), Giardia spp. (13.0%), Eimeria spp. (10.0%), Clostridium perfringens type A (8.0%), bovine torovirus (8.0%), bovine viral diarrhea virus (6.0%), bovine coronavirus (5.0%), bovine norovirus (2.0%) and Cryptosporidium spp. (2.0%) were detected. Nebovirus, kırklareli virus, bovine adenovirus, Salmonella spp. and intestinal parasites were not detected. Of the 72 calves sampled in this age group, 64 (88.9%) samples were positive for at least one enteropathogen. BRV was identified in 34/72 (47.2%) samples from 27/48 (56.3%) farms. Subsequently, pathogenic E. coli (30.6%), kobuvirus (29.2%), BPaV (22.2%), Giardia spp. (15.3%), Eimeria spp. (9.7%), BVDV (6.9%), Cl. perfringens type A (6.9%), BCoV (4.6%) and Cryptosporidium spp. (2.8%) were detected in fecal samples. A total of ninety-six strains of E. coli were isolated from one hundred fecal samples collected from Korean native cattle with diarrhea. The presence of stx1, stx2, eaeA, LT, STa, STb, ehxA, saa, F4, F5(K99), F6, F17, F18 and F41 genes in the isolates was investigated by PCR. Out of ninety-six E. coli isolates screened for specific genes, 30 strains E. coli were identified to harbor shiga toxin-producing E. coli (STEC) 7 (7.3%), enterohemorrhagic E. coli (EHEC) 8 (8.3%), enteropathogenic E. coli (EPEC) 6 (6.3%), enterotoxigenic E. coli (ETEC) 2 (2.1%) and STEC/ETEC hybrid 7 (7.3%). This study provides epidemiological estimates of the prevalence of Korean native cattle's enteropathogens in Gwangju area, Korea, which would be used for cattle farmers and veterinarians to select appropriate therapeutic method.

• Journal of Mushroom
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• v.5 no.1
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• pp.34-38
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• 2007

The white-colored and the dark gray-colored mutants were frequently happened in cultivated areas of Pleurotus ostreatus (Wonhyeong-neutari). These caused conflicts between farmers and spawn companies. Our studies were conducted to elucidate the mechanism of mutagenesis. The results from the studies would provide valuable informations that could be used to prevent the color-related mutation, and also will be applied in breeding programs of P. ostreatus. Oyster mushroom variety, Wonhyeong-neutari, is somatic hybrid of Pleurotus and has genetic makers for arginine, ornithine, proline, riboflavine. Genetic markers analysis of monospore isolates derived from color mutants show identical tendency with that of Wonhyeong-neutari, these results indicate that color mutants were derived from Wonhyeongneutari. Twenty-one and four homokaryons were selected from the white-colored mutant MGL 2205 and gray-colored ASI 2029. All 34 F1 hybrids derived from the white-colored mutant MGL 2205 produce white-color fruiting bodies, indicating that the white color trait is heritable. In the first generation hybrids between the white-colored MGL 2205 and the gray-colored ASI 2029, all 16 hybrids produced pigmented fruiting bodies. Homokaryons isolated from the hybrid MGL 2205 X ASI 2029 were mated with homokaryon tester strains derived from MGL 2205. By these result, we could assumed that white color trait is a heritable character which is controlled by more than one recessive gene.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.195-206
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• 1980

Fish were grown in a water recycling rearing system consisting of a filter system, of which the area is about $30\;m^2$ and the volume of filter gravels is about $15\;m^3$, 6 rearing and 2 supplementary tans about $7\;m^2$ of surface area each. The results for 180 days from April 18 to October 14,1980 are summarized as following: One rearing tank was used for main experiment stocked with an equal number, and weight of each Israeli strain and $F_1$, hybrid between this strain and Korean local strain of common carp. Gross total production was 461 kg with a net production of 395 kg, and the Israeli strain grew to about 8 times initial weight and the hybrid about 6 times. Based on an analysis of results of the above mentioned main experiment and the other miscellaneous fish grown in the remaining tanks, it was considered to be feasible to implement a commercial production in this system by improving parts of the system and adding a number of the units. A special problem seems to be an adoption of more effective aeration device when fish loading increases. A solid waste removal system was deviced by use of by-pass flow ana this system worked very efficiently in view of supply water economy. A serious problem encountered in this experiment was heavy outbreaks of the gill-fluke, Dactylogyrus sp. which was relatively easily eradicated with Dipterex or DDVP treatment in the first trials, but later on strains which were resistant to any of these chemicals appeared.

• Journal of Mushroom
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• v.17 no.4
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• pp.224-229
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• 2019

The two most common mushroom species grown in Korea are pearl oyster mushroom (Pleurotus ostreatus) and king oyster mushroom (P. eryngii). In recent years, the production of king oyster mushroom greatly increased due to the automation of the cultivation facilities, and it became a major export mushroom owing to its excellent shelf life. However, the increase in the production of king oyster mushroom led to a decline in its market price; thus, necessitating the development of new mushroom species that could replace king oyster mushroom, to diversify the mushroom market for the benefit of both, the producers and the consumers. The Mushroom division at the National Institute of Horticultural & Herbal Science (NIHHS) reported the development of a new interspecific hybrid between P. ferulae and P. tuoliensis, referred to as 'Creamy.' Two parental strains KMCC00430 (Bisan2ho, P. ferulae) and KMCC00461 (P. tuoliensis) were selected based on the results of genetic resource analysis, and their monokaryons were collected. About 1,000 Mon-Mon crosses were performed and 73 of them were selected. Following repeated cultivation tests and strain analyses, we selected strain 7773, which had a bright creamy pileus and a thick straight stipe, and named it 'Creamy.' Optimum temperature for mycelial growth of Creamy was 25-30℃, and that for fruiting body growth was 16℃. The pileus, which had a brighter creamy color, was small in size with a diameter of 61.2 mm. Although it was cultivated in suboptimal conditions, such as low temperature and high CO₂ concentration, Creamy was characterized by its straight and smooth stipe. Field production tests and further analyses indicated that the yield of Creamy was 5% higher than that of Baekhwang. It is expected that Creamy, the new interspecific hybrid with a bright creamy pileus and a pleasant flavor, will help create new opportunities for mushroom farmers and diversify the mushroom market.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.121-121
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• 2003

The standard protocol for the production of transgenic mouse from ES-injected embryo has to process via chimera producing and several times breeding steps, In contrast, tetraploid-ES cell complementation method allows the immediate generation of targeted murine mutants from genetically modified ES cell clones. The advantage of this advanced technique is a simple and efficient without chimeric intermediates. Recently, this method has been significantly improved through the discovery that ES cells derived from hybrid strains support the development of viable ES mice more efficiently than inbred ES cells do. Therefore, the objective of this study was to generate transgenic mice overexpressing human resistin gene by using tetrapioid-ES cell complementation method. Human resistin gene was amplified from human fetal liver cDNA library by PCR and cloned into pCR 2.1 TOPO T-vector and constructed in pCMV-Tag4C vector. Human resistin mammalian expression plasmid was transfected into D3-GL ES cells by lipofectamine 2000, and then after 8~10 days of transfection, the human resistin-expressing cells were selected with G418. In order to produce tetraploid embryos, blastomeres of diploid embryos at the two-cell stage were fused with two times of electric pulse using 60 V 30 $\mu$sec. (fusion rate : 93.5%) and cultured upto the blastocyst stage (development rate : 94.6%). The 15~20 previously G418-selected ES cells were injected into tetraploid blastocysts, and then transferred into the uterus of E2.5d pseudopregnant recipient mice. To investigate the gestation progress, two El9.5d fetus were recovered by Casarean section and one fetus was confirmed to contain human resistin gene by genomic DNA-PCR. Therefore, this finding demonstrates that tetraploid-ES mouse technology can be considered as a useful tool to produce transgenic mouse for the rapid analysis of gene function in vivo.

• Radiation Oncology Journal
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• v.3 no.2
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• pp.169-174
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• 1985

The mouse is one of the most popular experimental animal which has wide variation of strains, diet, environment, breeding technique, and diurnal cycle. Total 731 mice (male 372, female 359) were used for the standard data of our laboratory. Proper age for experiment were $30\pm3$days, body weight were $25\pm2gm (male)$, $23\pm1gm$. (female), minimal diurnal variation showed from 9A.M. to 12P.M.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.329-337
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• 2000

An investigation has been performed to develop an analysis tool based on a nonlinear beam theory, which can be used to predict the long-term behavior of an artificial hip joint. The nonlinear behav ior of the femur arise from the coupled dependence of the bone density and the mechanical properties on each other. The beam theory together with its numerical algorithm is developed to take into account the nonlinear bone remodeling process of the femur that is long enough to be assumed as a beam. A piecewise linear curve for the bone remodeling rate is used in the bone remodeling theory and the surface area density of bone is modeled as the third order polynomial function of bone density. At each section of the beam, a constant curvature is assumed and the longitudinal strains are also assumed to vary linearly across the section. The Newton-Rhapson iteration method is used to solve the nonlinear equations for each cross section of the bone and a backward method is used to march along the time. The density and the remodeling signal ar, calculated along with time for the various time steps, and the developed beam theory has been verified by comparing with the results of finite element analysis of a remodeling bone with an artificial hip joint of titanium prosthesis subjected to uni-axial loads and pure bending moment. It is concluded that the developed beam theory can be used to predict the long-term behavior of the femur and thus to design the artificial hip prosthesis.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.399-405
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• 1999

Intergeneric hybrids between Saccharomyccopsis fiburigera KCTC 7393 and Saccharomyces cerevisiae KCTC 7049 (tyr-, ura-) were obtained by nuclear transfer technique. Nuclei isolated from the wild type S. fiburigera strain were transfered into auxotrophic S. cerevisiae mutants and new strains showing an increased starch degrading capability were selected. Maximum production of protoplasts was obtained from the treatment with 0.1 % Novozym 234 at $30^{\circ}C$ for 90 min, and most effective osmotic stabilizer for the isolation of protoplasts was 0.6 M KCl at pH 5.8. The frequency of protoplast regeneration was 14.64% under the conditions. Genectic stability, conidial size, DNA content, and nuclear stain suggested that the fusants were aneuploidy. The specific activity of ${\alpha}-amylase$ was observed to increase about $1.2{\sim}1.9$ folds.

• Journal of Sericultural and Entomological Science
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• v.7
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• pp.49-52
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• 1967

In the F$_1$ hybrids and parents of silkworms, the silkworms of 47 blocks in summer and 68 blocks in fall in 1965 were reared in order to know the effect of mortality on the difference of sex ratio. The results analyzed are as follows; 1. In Moran of Japanese strain-parent and Morean x Daedong of F$_1$ hybrid, there is of no effect of an increase and decrease of mortality on the sex ratio. So male is not always stronger than female. 2. In Daedong of Chinese strain-parent, the more the mortality in the blocks is, the higher the survival ratio of male pupa becomes. (Y=0.233x-41.67). 3. As the results mentioned above, the present investigation method of cocoon quality of Chinese strains with the same number of cocoons of both sexes will have to be considered again, according to the cocoon crops, as far as concerned with the reasonable sampling from the population.

• The Korean Journal of Mycology
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• v.17 no.3
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• pp.154-160
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• 1989

The nuclear transfer technique was employed to obtain intraspecific hybrids in Aspergillus nidulans. Nuclei isolated from either a wild type or an auxotrophic mutant strain (FGSC 475) were transferred into the protoplasts of a recipient strain (FGSC 514). The frequency of hybrid formation (4.8% and 10.1 %, respectively) by nuclear transfer was higher than the frequency (0.6%) by protoplast fusion. Furthermore, most of the hybrids formed showed increased activity of some components of cellulase system, xylanase system, and mannanase. The hybrids were analyzed to be either diploid or aneuploid. These results suggest that nuclear transfer technique is more efficient the formation of intraspecific hybrids than protoplast fusion method and is useful for the improvement of Aspergillus strains.