• Journal of Microbiology and Biotechnology
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• 제7권5호
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• pp.341-344
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• 1997

Batch cultures of Anacystis nidulans BD-1 resistant to azaleucine and fluorotyrosine produced and liberated a wide range of amino acids, notably glutamic acid, alanine, phenylalanine, leucine, isoleucine, cysteine and methionine. Sustained liberation for prolonged periods was achieved after immobilization on calcium alginate and the net concentration in the medium was 0.18-0.2 g $I^{-1}$. While acetohydroxy acid synthase in azaleucine-resistant mutant lost leucine- and isoleucine-sensitivity, fluorotyrosine-resistant strain turned phenylalanine activating. The activities of nitrate assimilating enzymes were also higher in the mutants and were relaxed from ammonium-repression. The metabolic adjustments involved in amino acid overproduction are discussed.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1211-1216
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• 2004

A MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) induced chromium resistant strain ($Cr^{r}18$) of unicellular cyanobacterium Anacystis nidulans has been isolated and characterized. The resistant strain could grow (although restricted to $50\%$ of control) in chromium concentration (180${\mu}M$) lethal to the wild-type. Sublethal ($160{\mu}M$) concentration of $Cr^{6+}$ significantly reduced (13-$37.5$) all the photosynthetic pigments of A. nidulans with maximum reduction in phycoerythrin followed by ChI $\alpha$. Pigments of A. nidulans were drastically decreased in lethal concentration of Cr^{6+} with maximum reduction in phycoerythrin ($75\%$) and allophycocyanin ($67.5\%$). Resistant strain $Cr^{r}18$ resisted toxic effects of sublethal and lethal concentrations of $Cr^{6+}$ on photosynthetic pigments as revealed by less decrease in pigments as compared to A. nidulans. Effect of $Cr^{6+}$ stress was also studied on nitrogen assimilation and phosphate uptake. Sublethal concentration of $Cr^{6+}$ drastically reduced ($71.5\%$) nitrate uptake by A. nidulans while a decrease of $29\%$ was observed in strain $Cr^{r}18$. Short (2 day) exposure of A. nidulans and its resistant strain $Cr^{r}18\;to\;Cr^{6+}$ did not affect nitrate reductase and glutamine synthetase (transferase), whereas longer (10 day) exposure to $Cr^{6+}$ lowered activities of both enzymes in A. nidulans but not significantly in the strain $Cr^{r}18$. Ammonium uptake by both strains was not affected by $Cr^{6+}$. Thus, $Cr^{6+}$ affected photosynthetic pigments, nitrogen assimilation, and phosphate uptake of A. nidulans, while strain $Cr^{r}18$ was able to resist toxic effects of the metal. Advantages of using strain $Cr^{r}18$ for bioremediation purposes have been evaluated by studying $Cr^{6+}$ removal from the solution. Resistant strain $Cr^{r}18$ was able to remove $33\%$ more $Cr^{6+}$ than A. nidulans and thus it can prove to be a good candidate for bioremediation of $Cr^{6+}$ from polluted waters.

• Journal of Plant Biology
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• 제38권1호
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• pp.1-10
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• 1995

Photoinhibition and its recovery of spectrally adapted Anacystis nidulans were studied. Phycocyanin and Chl content and phycocyanin/Chl ratio were increased in cells grown under blue-green light compared with those grown in white light. Photosynthetic activities of white light and blue-green light grown cells were reduced by 50% after 15 min and 10 min of photoinhibitory light treatment (1.2 mmol·m-2s-1), respectively, largely due to the decline of PSII activities. However, their activities were recovered fully after 30 min incubation under weak light. Treatment of rifampicin and chloramphenicol magnified the photoinhibitory effects and suppressed the recovery with disappearance of susceptibility to photoinhibition and delayed the recovery process, indicating no significant differences in phosphorylation, dephosphorylation and protease activity between two cells. Therefore, it is suggested that the increased sensitivity of blue-green adapted cells might be attributed to the decline of protein synthesis, and phosphorylation-dephosphorylation of protein and protease activity might be involved in the recovery process.

• 한국잡초학회지
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• 제13권2호
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• pp.81-88
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• 1993

광합성 전자전달저해제의 탐색을 위한 biorational biorational screening 방법으로 광합성 박테리아의 일종인 cyanobacteria의 표준형과 $D_1$단백질의 구성 아미노산이 변환된 변이주 Di-1, G-264, Di-22, TRY-5를 사용하여 기존 약제의 혼합효과와 몇가지 합성화합물의 Hill반응 저해활성을 측정 조사하였고, 또한 시금치로 부터 분리한 chloroplast와 cyanobacteria로 부터 분리한 thylakoid membrane에 대한 기존 제초제의 반응성을 조사하였다. 1. 광합성억제형 제초제에 대한 반응성 비교에서 cyanobacteria로 부터 분리한 thylakoid membrane이 시금치로 부터 분리한 chloroplast보다 약제에 대하여 민감한 반응을 나타내어 광합성 전자전달저해제의 탐색을 위한 재료로 보다 적합하였다. 2. Diuron에 대하여 wild type보다 Di-22와 D-5 변이주는 각각 약 2,000배와 800배의 저항성을 나타내었고 atrazine에 대하여는 G-264 변이주만이 약 1,000배의 저항성을 나타내었으며, 기타 네 약제에 대하여는 뚜렷한 저항성을 나타내는 변이주가 없었다. 3. D1 단백절의 264번 위치의 serine이 다른 아미노산으로 치환된 Di-1과 D-22 및 G-264 변이주에 대한 diuron과 atrazine의 혼합처리 효과를 검토한 결과 상호 경합적으로 작용하였으며 그 정도는 G-264 변이주에 대해서 가장 뚜렷하게 나타났다. 그러나 diurone과 atrazine의 혼합처리에 의한 thermoluminescence band의 변화는 인정할 수 없었다. 4. 변이주 Di-1과 D-22는 dinoseb에 대해서 저항성을 나타내지 않았으나. dinoseb과 diuron의 혼합처리시 diuron에 대한 저항성이 크게 약화되었다.

• 한국잡초학회지
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• 제13권2호
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• pp.89-95
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• 1993

광합성 전자전달저해제의 탐색을 위한 biorational screening 방법으로 광합성 박테리아의 일종인 cyanobacteria의 표준형(wild type)과 $D_1$ 단백질의 구성 아미노산이 변환된 변이주 Di-1, G-264. Di-22 등 4종을 사용하여 신규합성 화합물에 대한 광합성 전자전달저해활성을 조사하여 구조-활성간의 특성을 검토하였고, 이들의 thermoluminescence band를 이용하여 결합부위를 비교하였다. 1. Phenol 화합물(E-series)들은 cyanobacteria를 이용한 광합성 전자전달 저해활성의 양상을 볼 때 diuron보다는 dinoseb과 비슷하였다. 2. 합성한 Phenol화합물에서 나타난 구조활성간의 특정으로는 치환기의 phenyl ring에 C1이 치환되지 않은 경우 Hill반응 저해활성이 나타나지 않았고, 화합물에 있는 두개의 ring을 연결하는 bridge의 길이가 길어질수록 Hill반응 저해활성은 약하게 나타났다. 3. Triazine 화합물(T-series)의 경우 T-27, T-28화합물은 대조약제 atrazine보다 각각 10, 30배 강한 저해활성을 나타내었고, 변이주 G-264에 대 한 저항성 비율이 atrazine보다 더욱 크게 나타나 이들 화합물들의 결합부위가 $D_1$ 단백질의 264번 위치와 깊은 관계가 있을 것으로 생각되었다. 4. Triazine 화합물에 있어서 치환기 -C-NH-는 전자전달계에 중요한 작용기로 생각되었다. 5. Thermoluninescence band를 이용하여 결합부위를 비교할 수는 있었지만, 명료하게 구분되지 않았다.