• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.140-144
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• 2012

This study was aimed for identification of a useful genetic resources from the entomopathogenic bacteria infected-midgut of the silkworm, Bombyx mori L. We analyzed the appropriately midgut-immunizing condition of $4^{th}$ instar larvae by a feeding infection using several entomopathogenic bacteria. Xenorhabdus nematophila was selected as a suitable bacteria for midgut immunization of Jam 123, B. mori. We constructed a subtraction cDNA library from the mRNA of the immunized midgut, respectively. A total of 1,000 clones were randomly selected from the subtracted cDNA library, and then performed a differential display hybridization analysis with forward and reverse probes. In conclusion, nine clones were identified as differential expressed genes, which presumed that these genes were involved in gut immunity of silkworm. The total number of clones analyzed in this work is not enough to have a brief overview of a understanding on the midgut immunity factors of silkworm. Therefore, further defined studies on these molecules biological roles will give us well-fined information about the innate immune mechanism of silkworm.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.440-446
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• 2004

Interest in in vitro study of entomopathogenic fungi, including Cordyceps species, has been increasing due to their valuable bioactive compounds and biocontrol effects. Among Cordyceps species, in vitro stromata of C militaris has been successfully produced and cultivated for industrial purposes. However, genetic study on in vitro stromata formation of C militaris has not been carried out yet. Here, relationship between mating system and perithecial stromata formation of C militaris is reported. Mating system was determined by observing perithecial stromata formation from mono-ascospore cultures and their pair-wise combinations. Certain combinations of mono-ascospore strains produced perithecial club-shaped stromata, whereas other combinations produced either no stromata or only abnormal non-perithecial stromata. Similarly, mono­ascospore cultures without combination produced either no stromata or only abnormal non­perithecial stromata. Despite obvious heterothallism, self-fertility was occasionally observed in few strains of C militaris. These observations indicated that C militaris behaves as a bipolar het­erothallic fungus and requires two mating compatible strains in order to produce regular club­shaped perithecial stromata, a fundamental requirement for its industrial cultivation.

• Mycobiology
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• v.40 no.2
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• pp.111-116
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• 2012

Ten strains of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were evaluated to find the most effective strain for optimization studies. The first criterion tested for strain selection was the mortality (> 50%) of Spodoptera litura larvae after inoculation of the fungus for 4 days. Results on several bioassays revealed that B. bassiana BNBCRC showed the most virulence on mortality S. litura larvae (80% mortality). B. bassiana BNBCRC also showed the highest germination rate (72.22%). However, its conidia yield ($7.2{\times}10^8$ conidia/mL) was lower than those of B. bassiana B 14841 ($8.3{\times}10^8$ conidia/mL) and M. anisopliae M6 ($8.2{\times}10^8$ conidia/mL). The highest accumulative radial growth was obtained from the strain B14841 (37.10 mm/day) while the strain BNBCRC showed moderate radial growth (24.40 mm/day). M. anisopliae M6 possessed the highest protease activity (145.00 mU/mL) while M. anisopliae M8 possessed the highest chitinase activity (20.00 mU/mL) during 96~144 hr cultivation. Amongst these criteria, selection based on virulence and germination rate lead to the selection of B. bassiana BNBCRC. B. bassiana B14841 would be selected if based on growth rate while M. anisopliae M6 and M8 possessed the highest enzyme activities.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.906-909
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• 2001

In order to investigate fatty acid contents and effects of cell growth on the production of an extracellular protease and toxicity of exotoxin, several symbiotic bacteria with highly effective toxins were isolated from seven species of entomopathogenic nematodes belong in Steinernematidae(Steinernema glaseri XR-DR, S. glaseri XR-NC, S. glaseri XR-MK, S. carpocapsae XR-PC, S. maticola XR-MO, S. Longicaudum XR-LC) and Heterorhabditidae sp.(Heterorhabditis bacteriophora XR-HY). In the cell growth and exotoxin toxicity, XR-PC and XR-MK were superior to other species when cultured in vitro. The protease activity of XR-DR was remarkable compared to other species. In the case of XR-HY, the protease activity increased in parallel with cell growth. Interestingly the fatty acid contents of XR-PC and XR-HY were significantly different from those of other species 12:0, 14:0, 13:0 iso, 16:1 cis 5 and 17:0 cyclo.

• BMB Reports
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• v.38 no.2
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• pp.211-217
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• 2005

Cordyceps, an entomopathogenic fungus, contains many health-promoting ingredients. Recent reports indicate that the consumption of cordyceps helps reduce blood-sugar content in diabetics. However, the mechanism underlying this reduction in circulatory sugar content is not fully understood. Methanolic extracts were prepared from the fruiting bodies of Paecilomyces tenuipes, and 4-beta acetoxyscirpendiol (4-ASD) was eventually isolated and purified. $Na^+$/Glucose transporter-1 (SGLT-1) was expressed in Xenopus oocytes, and the effect of 4-ASD on SGLT-1 was analyzed utilizing a voltage clamp and by performing 2-deoxy-D-glucose (2-DOG) uptake studies. 4-ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose-dependent manner. In the presence of the derivatives of 4-ASD (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited in an 4-ASD-like manner. Of these derivatives, 15-acetoxyscirepenol inhibited SGLT-1 as well as 4-ASD, whereas diacetoxyscirpenol was slightly less effective. Taken together, these results strongly indicate that 4-ASD in P. tenuipes may lower blood sugar levels in the circulatory system. We conclude that 4-ASD and its derivatives are effective SGLT-1 inhibitors.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.83-86
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• 2001

Effects of photoperiods, 24L or 24D, on the growth of the silkworm-dongchunghacho, the silkworm vegetable wasp and plant worm, were investigated. Exposure of the fungi under the photoperiod of 24L for at least 3 days during the cultivation of the fungi after the completion of endosclerotium in the host accelerated the spore formations but the growth of the fruiting bodies was inhibited. On the contrary, the photoperiod of 24D inhibited the spore formation, but accelerated the growth of fruiting bodies without spores. Accordingly, to produce silkworm vegetable wasp and plant worm of large-size fruiting bodies with over 3 cm in length, it is indicated that recommendable light condition is a photoperiod of 24D during the cultivation until the length of the fruiting body arrives at over 3 cm.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.968-978
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• 2007

A pathogenic nematode, Butlerius sp., was isolated from Oriental beetle, Blitopertha orientalis. The infective juveniles exhibited dose-as well as time-dependent entomopathogenicity on the larvae of B. orientalis. Two bacterial species, Providencia vermicola (KACC 91278) and Flavobacterium sp. (KACC 91279), were isolated from the infective juveniles and identified. P. vermicola outnumbered Flavobacterium sp. in the nematode host, in which the colony density of P. vermicola was found to be 21 times higher than that of Flavobacterium sp. However, when the two bacterial species were cocultured in culture media without the nematode host, they showed similar growth rates. Both bacteria induced significant entomopathogenicity against Spodoptera exigua larvae infesting economically important vegetable crops, where P. vermicola was more potent than Flavobacterium sp.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.77-80
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• 2000

This study was carried out to investigate infection process, symptoms and $LD_{50}$ values of the entomopathogenic fungus cordyceps, Paecillomyces japonica, on the domestic silkworm, Bombyx mori. Susceptibility of infection in the silkworms by cordyceps, Paecillomyces japonica, was 100% in $10^{7}$ block, 96% in $10^{6}$ block, 76% in $10^{5}$ block, 44% in $10^{4}$ block, 28% in $10^{3}$ block and 8% in $10^{2}$ block. Cordyceps, Paecillomyces japonica, was highly infectious to the silkworms. A pathogenicities of cordyceps, Paecillomyces japonica, may be highly virulent because of the low resistance or high susceptibility of the silkworms. Dosage of the pathogen of $LD_{50}$ was $3.78{\times}10^{3}\;spores/mm^{3}$.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.869-873
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• 2011

Most medium formulations for improving culture of entomopathogenic nematodes (EPN) based on protein sources have used enriched media like animal feed such as dried egg yolk, lactalbumin, and liver extract, among other ingredients. Most results, however, showed unstable yields and longer production time. Many of the results do not show the detailed parameters of fermentation. Soy flour, cotton seed flour, corn gluten meal, casein powder, soytone, peptone, casein hydrolysates, and lactalbumin hydrolysate as protein sources were tested to determine the source to support optimal symbiotic bacteria and nematode growth. The protein hydrolysates selected did not improve bacterial cell mass compared with the yeast extract control, but soy flour was the best, showing 75.1% recovery and producing more bacterial cell number ($1.4{\times}10^9$/ml) than all other sources. The highest yield ($1.85{\times}10^5$ IJs/ml), yield coefficient ($1.67{\times}10^6$ IJs/g medium), and productivity ($1.32{\times}10^7$ IJs/l/day) were also achieved at enriched medium with soybean protein.

• The Korean Journal of Pesticide Science
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• v.13 no.3
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• pp.177-184
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• 2009

This study was carried out to investigate infection process, symptoms and main component of the domestic silkworm, Bombyx mori. larvae and pupa infected with the entomopathogenic fungus Cordyceps, Paecillomyces tenuipes. The Cordyceps, Paecillomyces tenuipes, was highly infectious to the silkworms. A pathogenicities of Cordyceps, Paecillomyces tenuipes, may be highly virulent because of the low resistance or high susceptibility of the silkworms. The silkworm larva infected with Cordyceps formed phialospores on the phialides at the imperfect stage of the genus Cordyceps, But silkworm pupa infected with Cordyceps formed ascospores in the asci at the perfection stage of the genus Cordyceps. The results of analysis of health silkworm pupa and silkworm pupa infected with Cordyceps were obtained that amino acid, fatty acid, and nucleoside were very different.