• KSBB Journal
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• v.27 no.3
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• pp.172-176
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• 2012

In this study, microalgae Arthrospira platensis (A. platensis) mutants induced by ethyl methane sulfonate (EMS) and further selection for resistance of cerulenin, a potent inhibitor of fatty acid synthase, were characterized. The mutants selected by $2{\mu}M$, $5{\mu}M$ and $10{\mu}M$ of cerulenin were designated EC2, EC5 and EC10, respectively. Under normal growth conditions, the mutants and parental strain exhibited similar growth pattern. The mutants of A. platensis showed enhanced lipid accumulation and phycobiliproteins (phycoerythrin, phycocyanin). The lipid content of mutants EC2 and EC5 was about 4.4 and 4.8-fold higher than wild type. The phycoerythrin and phycocyanin content of mutants EC2 and EC5 was increased about 1.5 and 6.9-fold and 1.4 and 3.8-fold, respectively, compared to the wild type. The chlorophyll and carotenoid content of mutants was slightly increased. The high lipid and pigment contents exhibited by A. platensis mutants would make an excellent candidate for the production of commercially interesting biologically active compounds.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.583-588
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• 1998

This study was conducted to investigate the potential of nitrate-nonutilizing mutants (nit mutants) in ecological studies of Fusarium disease of strawberry. Nit mutants of Fusarium oxysporum from strawberry were easily formed on chlorate-containing media. Nit mutants were assigned to three phenotypic classes, nit1, nit3, and NitM, on the basis of their growth on media containing one of the following five different nitrogen sources ; nitrate, nitrite, hypoxanthine, ammonium and uric acid. Frequency of nit mutation and proportion of three phenotypes of nit mutants depended on the isolate. Mutation rate was 45.6% and ranged from 15.0% to 95.0%. The frequency of nit1 mutants was higher than that of nit3 or NitM. The complementary reaction between nit1 and NitM was higher than that of other combination. There has been no complementary response observed between nit3 and nit3. The nit mutants showed similar growth pattern as the that of wild type isolate on potato sucrose agar and potato sucrose liquid media. Most of the mutants retained pathogenicity, and maintained their phenotypes even after two year preservation through subculture on slanted PSA at room temperature. Nit mutants were selctively isolated from infested soil and infected plants on the selective medium (MMCPA) containing potassium chlorate with their original phenotypes, while naturally occurring isolates of Fusarium oxysporum were not grow on the medium. On the contrary, nit mutants showed very slight growth on the medium (MMPA) containing nitrate as a sole nitrogen source, and therefore could be distinguished from wild type isolate.

• The Plant Pathology Journal
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• v.19 no.6
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• pp.301-304
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• 2003

Gamma-ray irradiation is known to induce various mutations in plants caused by chromosome alterations. This study investigated disease responses of selected gamma-ray induced rice mutants generated from seven Japonica-type rice cultivars against three plant diseases. Among the tested 22 mutants, three gain-of-function mutants and six loss-of-function mutants against rice blast were obtained, as well as three loss-of-function mutants against bacterial leaf blight (BLB). Two of the loss-of-function mutants were susceptible to both rice blast and BLB. Gain-of-function mutation has not been frequently observed in rice plants, thus, the mutants can be used to identify loci of novel genes for the regulation of disease resistant response.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.39-46
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• 1994

Pseudomonas fluorescens Biovar III strains S-2 antagonistic to Rhizoctonia solani was subjected to Tn5 mutagenesis by the transposon vector pGS9. Ampicillin and kanamycin resistant (Ampr, Kmr) transconjugants were recovered at a frequency of 1.3$\times$10-7 per initial recipient cell, when recipient cells were washed twice in TE buffer before conjugation. Of the ca. 3000 transconjugants, a frequency of noninhibitory (Inh-), nonfluorescent (Flu-) and auxotorphic (Pro-) mutants were 0.27%, 0.47% and 0.40%, respectively. In these mutants, all Inh- mutants showed the same colony morphology as wild type, whereas all Flu- and Pro- mutants inhibited the growth of R. solani. These mutants were also susceptible to chloramphenicol, indicating only the Tn5 element, except for parts of pGS9, was integrated into the recipient genome. In a Southern blot analysis, the Tn5 element inserted into one site on the chromosome for each of the chosen mutants. However, Tn5 insertion sites of Inh-, and Pro- mutants were differed in each other. These indicate that the genes essential for R. solani inhibition, fluorescent production and auxotrophic are chromosomally located, but not linked to each other.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.84-90
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• 2006

Various ${\Delta}opp$ mutants of Vibrio fluvialis were constructed by allelic exchange method. The mutants occurred in target genes were confirmed by PCR and Southern hybridization analyses. After the exact mutants were identified, cell growth and biofilm production were examined using the respective mutants. The growth of wild strain was more rapid than mutants within 4hr incubation. Thereafter, the growth of wild strain and mutants reached to same level. When the productivities of wild strain and mutants were examined, ${\Delta}oppA$ mutant showed the highest productivity. Though ${\Delta}oppC,D$ and F mutants produced the lower production than that of ${\Delta}oppA$ mutant, the productivities of those mutants were much higher than that of wild strain.

• Journal of Microbiology
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• v.35 no.4
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• pp.334-340
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• 1997

A collection of 132 temperature sensitive (ts) mutants was generated by the chemical mutagenesis of Schizosaccharomyces pombe wild type strain and screened for tRNA splicing defects on Northern blots by hybridization with an oligonucleotide that recognizes the exon of the S. pombe tRNA^Val as a probe. We identidied 6 mutants which accumulate precursor $tRNA^{Val}$. Among them, 2 mutants exhibited remarkable morphological differences compared to wild type cells. One tRNA splicing mutant showed elongated cell shape in permissive as well as non-permissive cultures. The other mutant exhibited shortened cell morphology only in nonpermissive culture. The total RNA pattern in the splicing mutants appeared to be normal. Genetic analysis of four $tRNA^{Val}$ splicing mutants demonstrated that the mutation reside in different genes.

• BMB Reports
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• v.44 no.2
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• pp.102-106
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• 2011

Thermodynamic stability and refolding kinetics of firefly luciferase and three representative mutants with depletion of negative charge on a flexible loop via substitution of Glu by Arg (ER mutant) or Lys (EK mutant) as well as insertion of another Arg in ER mutants (ERR mutant) was investigated. According to thermodynamic studies, structural stability of ERR and ER mutants are enhanced compared to WT protein, whereas, these mutants become prone to aggregation at higher temperatures. Accordingly, it was concluded that enhanced structural stability of mutants depends on more compactness of folded state, whereas aggregation at higher temperatures in mutants is due to weakening of intermolecular repulsive electrostatic interactions and increase of intermolecular hydrophobic interactions. Kinetic results indicate that early events of protein folding are accelerated in mutants.

• Proceedings of the Botanical Society of Korea Conference
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• 1994.09a
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• pp.41-51
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• 1994

Tomato (Lycopersicon esculentum Mill.) has been chosen as a model species for the study of hotomorphogenesis. The aurea (au) and yellow-green-2 (yg-2) mutants which are severely photochrome deficient appear to be phytochrome chromophore mutants. Mutants modified with respect to specific members of the phytochrome gene family: the far-red light-insensitive mutant (fri, for phytochrome A) and the temporarily red light-insensitive mutant (tri, for phytochrome B1) have been identified. Mutants that exhibit an exaggerated phytochrome response are putative transduction-chain mutants affecting an amplification step in phytochrome signal transduction. These mutants are being used to understand the complexities of juvenile anthocyanin in the hypocotyl during seedling de-etiolation.

• The Plant Pathology Journal
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• v.16 no.5
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• pp.247-251
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• 2000

Latent infections of healthy-appearing oaks of Hypoxylon atropunctatum complicates field studies by interfering with inoculation experiments to follow pathogenesis, fungal development and reproduction of this canker rot fungus. Mutants with unique and easily scorable phenotypes would be useful for inoculation studies. There is a broad range in the capacity of wild-type isolates to utilize nitrate as a sole nitrogen sources. Several types of nitrate-nonutilization mutants (nit1, Nit3, NitM) were selected from nitrate-utilizing wild-type isolates. Also, a few mutants of Hypoxylon atropunctatum were selected that could only grow poorly on basal medium supplemented with various nitrogen sources and even on yeast extract agar. These unknown mutants need to be characterized further. Nit mutants of Hypoxylon atropunctatum were readily selected, grew well and were recovered after inoculation into oak stems. These results suggest that nit mutants could be useful for inoculation studies in trees that contain latent infections.

• Archives of Pharmacal Research
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• v.18 no.4
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• pp.243-248
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• 1995

Seventeen transformation-deficient mutants of streptococcus pneumoniae, which are defective in competence induction (com), DNA uptake(ent) of recombination(rec), were investigated to determine sensitivity to ethylmethane sulfonate(EMS), methylmethane sulfonate(MMS), UV and mitomycin C. In ethylmethane sulfonate assay, the viability of most $com^-, \; rec^-\; and ent^-$ mutants was decreased about 2-10 times and the viability of ent-9 and ent-13 mutant was decreased about 33 and 25 times, respectively. On the other hand only half of the transformation-deficient mutants tested was sensitive to methylmethane sulfonate about 2 times and ent-12 mutant was sensitive to 2.0% MMS about 8 times. After UV and mitomycin C treatment, most of the mutants are not sensitive to UV and mitomycin C, although the viability of some transformation-deficient mutants was decreased slightly. Especially none of the com mutants were sensitive to DNA damage suggesting that competence is not involved in DNA repair. Also DNA uptake and recombination gane might be related to DNA repair function.