• Mycobiology
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• 제43권2호
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• pp.137-149
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• 2015

In the search for novel potent fungi-derived bioactive compounds for bioinsecticide applications, crude ethyl acetate culture filtrate extracts from 110 mangrove fungal endophytes were screened for their toxicity. Toxicity tests of all extracts against brine shrimp (Artemia salina) larvae were performed. The extracts with the highest toxicity were further examined for insecticidal activity against Spodoptera litura larvae and acetylcholinesterase (AChE) inhibition activity. The results showed that the extracts of five isolates exhibited the highest toxicity to brine shrimp at 50% lethal concentration ($LC_{50}$) values of 7.45 to 10.24 ppm. These five fungal isolates that obtained from Rhizophora mucronata were identified based on sequence data analysis of the internal transcribed spacer region of rDNA as Aspergillus oryzae (strain BPPTCC 6036), Emericella nidulans (strains BPPTCC 6035 and BPPTCC 6038), A. tamarii (strain BPPTCC 6037), and A. versicolor (strain BPPTCC 6039). The mean percentage of S. litura larval mortality following topical application of the five extracts ranged from 16.7% to 43.3%. In the AChE inhibition assay, the inhibition rates of the five extracts ranged from 40.7% to 48.9%, while eserine (positive control) had an inhibition rate of 96.8%, at a concentration of 100 ppm. The extracts used were crude extracts, so their potential as sources of AChE inhibition compounds makes them likely candidates as neurotoxins. The high-performance liquid chromatography profiles of the five extracts differed, indicating variations in their chemical constituents. This study highlights the potential of culture filtrate ethyl acetate extracts of mangrove fungal endophytes as a source of new potential bioactive compounds for bioinsecticide applications.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 1996년도 제19회정기학술대회(The 19th Symposium of the Korean Society of Environmental Toxicology)
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• pp.70-70
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• 1996

The cytotoxicological effect of Bt 1-endotoxin, well-known as a bioinsecticide, was investigated on ion channel of insect cell lines. This study attempted to evaluted the specificity by simple experiment to measure the cell swelling using lepidopteran cell lines in isotonic solution containing only one cation. Cell swelling was stimulated in KCI-sucrose isotonic solution as well as TC-100 media containg in solubilized crystal 5-endotoxin. It suggested that the cell swelling by Bt toxin have a relation to K+ channel. The cell swelling may be due to the stimulation K+ influx and simultaneously the penetration of H2O induced by Bt toxin, because the stimulation of swelling was observed with the solubilized toxin in KCI-sucrose isotonic solution, but not in sucrose isotonic solution. Moreover the specific K+ channel blocker, such as 4-arnjnopyrimidine(4-AP) and ouabain, showed the significant effect on the cell swelling induced by Bt toxin. The increasement of the cell swelling induced by 4-AP suggested to be caused by the block of K+ efflux through K+ leak channels. The inhibition of cell swelling by ouabain, which is the well-known inhibitor of Na+, K+-ATPase, suggested to be due to decreasement of K+ influx following diminishment of Na+, K+-ATPase activities.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.12-16
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• 1999

Xenorhabdus nematophilus sp., an insect-pathogenic bacterium, was newly isolated from Korean entomopathogenic nematode of Steinernema carpocapsae, which can be used as a useful bioinsecticide. Primary and secondary form variants of Xenorhabdus nematophilus were observed when cultured in vitro. Primary form variants adsorbed bromothymol blue, while secondary form did not. However, many other characters of two variants were very similar. The variants were all rod-shaped and cell size was highly variable ranging from 0.5 by 2.0 ${\mu}$m to 1.0 by 5.0 ${\mu}$m. Both produced highly toxic substances and killed the insect larva within 20∼38 hr, indicating that insect pathogenicity of Xenorhabdus is not directly associated with its phase variation. In addition, cell-free culture supernatant of Xenorhabdus was sufficient to kill the insect larva by injecting it ito insect hemolymph; however, cell-harboring culture broth was more effective for killing the insect. The use of Xenorhabdus nematophilus may provide a potential alternative to Bacillus thuringiensis (Bt) toxins.

• 한국응용곤충학회지
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• 제36권1호
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• pp.37-42
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• 1997

우리나라의 곤충병원성곰팡이 분포를 조사하기 위하여 5개도와 3개 광역시에서 200개소의 토양 sample을 채집하여 꿀벌부채명나방 유충을 이용하여 분리하였다. 8종의 곤충 사체로 부터는 직접 분리하였다. 그 결과 40개소(20.0%)의 토양과 8종의 곤충 사체에서 곰팡이가 분리되었는데, 토양에서 분리된 균종별로는 Bequveria가 21개소(10.5%), Metarhizium이 19개소(9.5%)이었다. 그외 7종의 곤충에서 Beauvria가 분리되었다. 서식처별로는 산림 110개소중 25개소(22.7%), 경작지 20개소중 2개소(11.0%), 휴한지 11개소중 6개소(54.5%), 하천 제방 19개소중 7개소(36.8%)에서 곤충병원성곰팡이가 검출되었다. 한편, 곤충 사체에서는 긴수염 대벌레에서 Metarhizium이 분리된 것을 제외하고는 모두 Beauveria가 분리되었다.

• Journal of Applied Biological Chemistry
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• 제53권1호
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• pp.21-24
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• 2010

커스타드애플(Annona reticulata L.)씨 추출물 및 그의 분획물을 활용하여 복숭아혹진딧물 및 벼멸구를 대상으로 살충활성을 조사하였으며, 그 결과 아세톤/메탄올 조추출물 $3000\;{\mu}g/mL$에서 복숭아혹진딧물은 100%, 벼멸구에 대해서는 92%의 살충률을 나타내었다. 이들에 대한 $LD_{50}$는 각각 $446.3\;{\mu}g/mL$와 $1423.6\;{\mu}g/mL$로 복숭아혹진딧물이 추출물에 높은 감수성을 나타내었다. 이들의 핵산, 클로로포름, 물 분획물에 대한 분리정제물의 경우 클로로포름 분획물이 조추출물 분획물보다 약 3배 높은 살충능이 관찰되었으며, 이는 극성분배를 통해 살충성이 높은 물질군을 선별적으로 정제할 수 있음을 보여준다. 특히 클로로포름 분획물에 대한 살충능의 경우 $137.2\;{\mu}g/mL$(복숭아혹진딧물), $1145.5\;{\mu}g/mL$(벼멸구)의 농도에서 $LD_{50}$가 관찰되었다.

• 한국잠사곤충학회지
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• 제51권2호
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• pp.137-141
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• 2013

ITS 1, 2, 5.8S ribosomal RNA gene 염기서열 분석과 주사전자현미경 구조 분석을 통해 3종의 페루산 곤충병원성진균들의 동정을 수행하고자 하였다. 이를 위해 두개의 ITS 부위와 5.8S rRNA gene 부위를 포함하는 PCR product를 증폭하여 염기서열 분석을 수행하였으며 분석된 염기서열을 이용하여 NCBI의 BLAST를 이용하여 가장 높은 상동성을 보이는 종들의 ITS1-5.8S-ITS2 염기서열 정보와 비교분석을 위한 근연종들의 염기서열 정보를 다운로드하여 neighbor joining 분석을 수행하였다. 이를 통해 5.8S rRNA 유전자 염기서열은 속 수준에서도 거의 차이를 보여주지 않을 정도로 매우 안정적으로 보존되어 있음을 확인할 수 있었으며 종간 구분이 모호한 결과를 보여주었다. 그와 반대로 ITS 부위의 염기서열은 종에 매우 특이적임을 확인할 수 있었으며, 비교분석에 사용된 Beauveria bassiana strain 간의 차이는 확인할 수 없었다. ITS 염기서열 분석결과를 뒷받침하고자 곤충병원성 진균류의 동정을 위한 분류 key로 사용되는 미세구조 관찰을 위해 주사전자현미경 관찰과 광학현미경 관찰을 통해 B. bassiana 및 Lecanicillium attenuatum의 전형적 구조를 관찰할 수 있었다.