• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.342-347
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• 2003

Clumping of cells is one of the major obstacles to culture wild myxobacterial strains in liquid media. In an effort to solve this problem, we tried a method isolating spontaneous mutants that grow dispersed in liquid media from a wild myxobacterial strain. Myxococcus stipitatus KYC1001, a newly isolated strain from Gyearyongsan National Park in Korea, clumps and sticks to the surface of culture vessels as other wild myxobacteria behave in liquid media. Taking an advantage of the characteristics that dispersed mutant cells would grow dispersed while most other wild type cells would clump and stick to the surface of culture vessels, spontaneous dispersed mutants were enriched by repeated subculturing of culture supernatant. A resultant mutant, KYC2001, did not form any clumps nor stick to the surface of culture flasks, but grew completely dispersed in liquid. Meanwhile, three other spontaneous mutants, KYC2002, KYC2003, and KYC2004, shelved partially dispersed phenotype. A major portion of the cells grew dispersed in liquid but they still formed some clumps.

• Korean Journal of Microbiology
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• v.20 no.4
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• pp.173-182
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• 1982

From FGSC 159 strain of Aspergillus nidulans, temperature sensitive mutants that are defective in growth and differentiation have been isolated by N-methyl-N'-nitroN-nitrosoguanidine (NTG) treatment. The optimum concentration of NTG and incubation time to get the highest mutation frequency was $100{\mu}g$ per ml and 1 hour, respectively. The survival frequency was 1%. Among the isolated mutants, five strains that were affected in early steps of differentiation were selected for further studies and named smK, smY, smB, smF, and smZ. The execution point of each mutant was determined and the growing pattern of each mutant at the restrictive temperature was observed under the microscope. Growth of mutant was arrested near at the execution point. From genetic analysis, each temperature-sensitive mutants was thought to have a single recessive gene. The genes of smK, smY, smB, smF, and smZ are linked to the chromosome VII, IV, VIII, I, and VI, respectively. It can be concluded that the genes controlling the differentiation are widely dispersed in the genome. From the results of mutant, smK, it is considered that a single gene can affect a function (functions) which act(s) at two different steps during differentiation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.32-32
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• 2019

Mutation breeding is the useful tool to improve agronomic traits in various crop species. Soybean is most important crop and is rich in protein and oil contents. Despite of the importance as economic value and various genetic resource of soybean, there have been limited studies of genetic relationship among mutant resources through radiation breeding. In this study, the agronomical phenotype for selecting various genetic resources was evaluated in 528 soybean mutant lines. As a result, 210 soybean mutants with their original cultivars were selected with various traits. We named 210 selected lines as Mutant Diversity Pool (MDP). The genetic diversity and the relationship of the MDP were investigated using TRAP and TE-TRAP markers. In TRAP analysis, sixteen primer combination (PC)s were used and a total of 551 fragments were amplified. The highest (84.00%) and the lowest (32.35%) polymorphism levels were showed in PC MIR157B+Ga5 and B14G14B+Ga3, respectively. The mean of PIC values was 0.15 ranging from 0.07 in B14G14B+Sa12 to 0.23 in MIR157B+Sa4. Phylogenetic and population structure analysis indicated that the 210 MDP lines dispersed to four groups among the wild types and their mutants. The highest genetic diversity among populations was observed between lines Paldal and 523-7 (Fst=0.409), whereas the lowest genetic diversity was between population KAS360-22 and 94seori (Fst=0.065). AMOVA showed 11.583 (21.0%) and 43.532 (79.0%) variations in inter and intra mutant population, respectively. Overall, the genetic similarity of each intra mutant populations was closer than that of inter mutant population. A total of 408 fragments were amplified in the 210 MDP using twelve PCs of TE-TRAP markers that were obtained from a combination of three TIR sequence of transposable elements (MITE-stowaway; M-s, MITE-tourist; M-t, PONG). The highest (77.42%) and the lowest (56.00%) polymorphism levels were showed in PONG+Sa4 and PONG+Sa12, respectively. The mean of PIC values was 0.15 ranging from 0.09 in M-s+Sa4 and M-s+Ga5 to 0.21 in M-t+Ga5. AMOVA of M-s showed 2.209 (20%) and 8.957 (80%) variations in inter and intra mutant population, respectively. AMOVA of M-t showed 2.766 (18%) and 12.385 (82%) variations in inter and intra mutant population, respectively. AMOVA of PONG showed 3.151 (29%) and 7.646 (71%) variations in inter and intra mutant population, respectively. According to our study, the PONG had higher inter mutant population and lower intra mutant population. This mean was that for aspect of radiation sensitivity, M-s and M-t showed higher mobility than that of PONG. Our results suggest that the TRAP and the TE-TRAP markers may be useful for assessing the genetic diversity and relationship among soybean MDP and help to improve our knowledge of soybean mutation/radiation breeding.

• Development and Reproduction
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• v.27 no.4
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• pp.221-226
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• 2023

A stem cell niche provides an environment that governs stem cell maintenance and division. Thus, the development of a proper niche is of prime importance to stem cell behaviors. Mechanisms of niche development are beginning to be revealed in the Drosophila male gonad. Niche cells are initially dispersed throughout the gonad, then assemble at its apical tip through the anterior migration of posteriorly located niche cells. The molecular mechanisms of this migration and assembly are still poorly understood. Here we show evidence suggesting that Lin28, an RNA-binding protein and regulator of let7 genesis, might be an intrinsic factor for the anterior migration of niche cells. We found that a dispersed, ectopic niche, a phenotype observed with anterior migration defects, occurs in lin28 mutant gonads. This phenotype is rescued by expression of lin28 in the niche cells. These findings suggest that Lin28 might be required for the anterior migration of niche cells.

• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1884-1889
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• 2008

The ${\beta}$-lactamase inhibitory protein, BLIP-II, found in the culture supernatant of Streptomyces exfoliatus SMF19, shows no discernible sequence identity with other ${\beta}$-lactamase inhibitory proteins identified in Streptomyces spp. A null mutant of the gene encoding BLIP-II (bliB::$hyg^r$) showed a bald appearance on solid media. Although BLIP-II was initially isolated from the supernatant of submerged cultures, sites of BLIP-II accumulation were seen in the cell envelope. Mutation of bliB was also associated with changes in the formation of septa and condensation of the chromosomal DNA associated with sporulation. The bliB mutant exhibited infrequent septa, showing dispersed chromosomal DNA throughout the mycelium, whereas the condensed chromosomes of the wild-type were separated by regularly spaced septa giving the appearance of a string of beads. Therefore, on the basis of these results, it is suggested that BLIP-II is a regulator of morphological differentiation in S. exfoliatus SMF19.

• Molecules and Cells
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• v.40 no.9
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• pp.643-654
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• 2017

Autophagy is a degradation pathway in eukaryotic cells in which aging proteins and organelles are sequestered into double-membrane vesicles, termed autophagosomes, which fuse with vacuoles to hydrolyze cargo. The key step in autophagy is the formation of autophagosomes, which requires different kinds of vesicles, including COPII vesicles and Atg9-containing vesicles, to transport lipid double-membranes to the phagophore assembly site (PAS). In yeast, the cis-Golgi localized t-SNARE protein Sed5 plays a role in endoplasmic reticulum (ER)-Golgi and intra-Golgi vesicular transport. We report that during autophagy, sed5-1 mutant cells could not properly transport Atg8 to the PAS, resulting in multiple Atg8 dots being dispersed into the cytoplasm. Some dots were trapped in the Golgi apparatus. Sed5 regulates the anterograde trafficking of Atg9-containing vesicles to the PAS by participating in the localization of Atg23 and Atg27 to the Golgi apparatus. Furthermore, we found that overexpression of SFT1 or SFT2 (suppressor of sed5 ts) rescued the autophagy defects in sed5-1 mutant cells. Our data suggest that Sed5 plays a novel role in autophagy, by regulating the formation of Atg9-containing vesicles in the Golgi apparatus, and the genetic interaction between Sft1/2 and Sed5 is essential for autophagy.