• Journal of Microbiology
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• v.39 no.2
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• pp.102-108
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• 2001

DNA damage response has a central role in the maintenance of genomic integrity while mutations in related genes may result in a range of disorders including neoplasic formations. The uvsZl characterized in this report is a navel uvs mutation in Aspergillus nidulans, resulting in a nucleotide excision repair (NER) phenotype: UV-sensitivity before DNA synthesis (quiescent cells), high UV-induced mutation frequency and probable absence of involvement with mitotic and meiotic recombinations. The mutation is recessive and nan-allelic to the previously characterized uvsA101 mutation, also located on the paba-y interval on chromosome I. uvsZl skewed wild-type sensitivity to MMS, which suggests non-involvement of this mutation with BER. Epitasis tests showed that the uvsZ gene product is probably involved in the same repair pathways as UVSB or UVSH proteins. Although mutations in these proteins result in an NER phenotype, UVSB is related with cell cycle control and UVSH is associated with the post-replicational repair pathway. The epistatic interaction among uvsZl and uvsB413 and uvsH77 mutations indicates that different repair systems may be related with the common steps of DNA damage response in Aspergillus nidulans.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.43-48
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• 1996

Mutangen sensitive hyper-rec type musN mutants were assigned into the UvsC group which contains genes involved in recombination and mutation. however, phenotypic properties of musN mutants were very different from those found in uvsC mutant strains which are rec- and lack UV-induced mutation. musN was not a mutator like uvsC. In addition, selenate resistant mutations in musN were induced sililar to those in wild types by UV irradiation. Wild type levels of UV-sensitivity in dividing cells of musN also differ from the uvsC phenotypes. These indicate that the UvsC group has branched pathways.

• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.23-30
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• 2007

The effects of high energy short wave solar radiation on human skin have received much publicity as the major cause of accelerated skin ageing and of skin cancers. To meet public demand, the cosmetic industry has developed sun protection factor products, which contain a variety of so-called "UV filters", among others benzophenone (BP) and its metabolites are the widely used UV filters. UV filters are also used to prevent UV light from damaging scents and colors in a variety of cosmetics products and to protect of plastic products against light-induced degradation. There are many variants of BP in use. In this respect, to regulate and to evaluate the hazardous effect of BP-type UV filters will be important to environment and human health. The genotoxicity of 7 BP-type UV filters was evaluated in L5178Y $(tk^{+/-})$ mouse lymphoma cells in vitro. BP, benzhydrol, 4-hydroxybenzophenone 2-hydroxy-4-methoxybenzophenone and 2, 4-dihydroxybenzophenone did not induce significant mutation frequencies both in the presence and absence of metabolic activation system. 2, 2'-Dihydroxy-4-methoxybenzophenone appeared the positive results at the highest dose, i.e. 120.4 ${\mu}g/mL$ only in the absence of metabolic activation system. And also, 2, 3, 4-trihydroxybenzophenone revealed a significant increase of mutation frequencies in the range of 138.1-207.2 ${\mu}g/mL$ in the absence of metabolic activation system and 118.3-354.8 ${\mu}g/mL$ in the presence of metabolic activation system. Through the results of MLA with 7 BP-type UV filters in L5178Y cells in vitro, we may provide the important clues on the genotoxic potentials of these BP-type UV filters.

• KSBB Journal
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• v.23 no.5
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• pp.392-397
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• 2008

Recently, importance of immunosuppression is increasing as internal organ transplant becomes more prevalent with development of medical technology. Mycophenolic acid (MPA) is a selective inhibitor of guanine synthesis and it therefore has antibacterial, antiviral, antitumor and selective immunosuppressive activities. The objective of this study was to maximize MPA productivity through utilizing the MPA generating strain of Penicillium brevicompactum ATCC 16024, by inducing UV mutation and NTG mutation. The highest MPA obtained was 1.146 g/L, 2.051 g/L, and 1.390 g/L from P. brevicompactum UB-3, UB-9, UC-4 respectively mutants derived from UV treatment. P. brevicompactum NC-3 and NA-9 induced from NTG treatment yielded. 575 g/L, 2.238 g/L of MPA production respectively. Mutants capable of the highest observed production of MPA were P. brevicompactum UB-9 and P. brevicompactum NC-3 obtained using the UV and NTG treatments respectively.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.584-592
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• 1994

Several mutation procedures have been compared to obtain an ethanol-tolerant Saccha- romyces diastaticus strain secreting glucoamylase. These procedures include spontaneous mutation, EMS treatment, UV irradiation, and combination of EMS treatment and UV irradiation. All these methods were followed by adaptation of the yeast cells to gradually higher ethanol concentration. Among these procedures, the combined method of EMS treatment and UV irradiation gave the promising result, i.e. the ethanol tolerance of the yeast increased from 11.5%(v/v) to 14.0%(v/v). Respiratory deficient petite mutants of industrial and ethanol-tolerant yeast strains have been isola- ted and hybridized with haploid S. diastaticus strains. The resulting hybrids showed increased ethanol tolerance and starch-fermentability.

• Journal of Marine Bioscience and Biotechnology
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• v.6 no.1
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• pp.26-30
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• 2014

Chlorella vulgaris, a genus of single-cell green algae, is considered to be a very essential resource for the higher value-added business including functional food and biodiesel, due to its high contents of protein, carbohydrate and lipid. In this study, ultraviolet rays were irradiated in order to induce the mutation of C. vulgaris. After inducing the mutation, UV1-20 mutant, high in lipid was selected and its cell growth rate, dry weight, pigment content and lipid content were measured. The growth rate of the UV1-20 mutant was increased almost 1.5 times than the wild type, but pigment contents of chlorophyll and carotinoid were decreased. In addition, the lipid content of UV1-20 was increased 1.8 times than the wild type. Therefore, C. vulgaris mutant, isolated in this study, is considered to have sufficient potential to be used as a material for the higher value-added business.

• Microbiology and Biotechnology Letters
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• v.32 no.2
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• pp.101-109
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• 2004

In order to enhance the productivity of AVM $B_{la}$ produced by Streptomyces avermitilis as a secondary metabolite, we established a basic protocol necessary for protoplast fusion with high-producing strains as a fusion partner, and then obtained various kinds offusants by adopting a massive strain-development procedure (a miniaturized strain screening system). An alternative fusion method using UV and/or NTG mutation of protoplasts was developed to screen genetic recombinants without specific selectable markers. In this method, the mutants obtained by protoplast fusion after UV and/or NTG treatment (95% death rate) of the respective fusion partner (protoplasts of the respective mutants resistant against L-isoleucine antimetabolites such as O-methylthreonine and/or azaleucine) were regarded as DNA-recombined protoplast fusants. Notably it was demonstrated that most of the protoplast recombinants obtained by the UV mutation method were able to biosynthesize higher amount of AVM $B_{la}$ , reaching almost three times higher level (almost equal to the industrial productivity), compared to the average AVM Bla amount of the parallel mother strains.

• Korean Journal of Microbiology
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• v.24 no.3
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• pp.221-227
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• 1986

The strain of Aspergillus nidulans carring a uvsH mutation which had been shown to be absolutely required for UV or 4-NQO induced mutagenic processes was studied on mitotic recombinational behaviour. Although the effect of uvsH locus on spontaneous mitotic crossing over between fpB37 and centromere was not considerable, UV-induced intergenic recombination did not occur in uvsH/uvsH homozygotic diploid. In case of gene conversion at riboflavin locus between a pair of non-complementary alleles, riboA1 and riboA3, the uvsH mutation was not concerned with that process occurred spontaneously or induced by UV irradiation. When the cells were irradiated by UV light, high degrees of aneuploid productions were detected in diploid homozygous for uvsH as compared with wild type, while much difference was not found during normal growth.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.144-150
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• 1997

After DNA damage, umuDC is the only SOS operon that must be induced to promote SOS mutagenesis in Escherichia coli. The recombinant plasmid pBC401 and pBC402 were constructed to fuse the lac structural genes with promoter region of umuDC operon to induce the expression of lacZ gene by DNA damage. We transformed the plasmid pBC401 and pBC402 into E. coli MC1061, lacZ deleted strain and determined the activity of $\beta$-galactosidase for various mutagen; UV, mitomycin C (MMC), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitroqunoline-1-oxide (NQO), ethyl methanesulfonate (EMS). The $\beta$-galactosidase activities of PBC401 and pBC402 for UV, MMC, and NQO were increased in proportion to expression time until 3 hours thereafter, the activities were constant or slightly decreased. The activities for MNNG and EMS were not so high as for UV, MMC, and NQO. When MNNG and EMS were treated, $\beta$-galactosidase activity of pBC402 was slightly lower than pBC401 but when UV, MMC, and NQO were treated in pBC402, $\beta$-galactosidase activity was slightly higher than in pBC401. Therefore, the pBC402 was better than the pBC401 in terms of sensitivity for frameshift mutagen. We suggest that the plasmid pBC401 and pBC402 are easy to detect mutagens which cause frameshift mutation rather than point mutation.

• Biomolecules & Therapeutics
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• v.25 no.4
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• pp.396-403
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• 2017

Under normal, non-stressed conditions, intracellular p53 is continually ubiquitinated by MDM2 and targeted for degradation. However, in response to severe genotoxic stress, p53 protein levels are markedly increased and apoptotic cell death is triggered. Inhibiting the ubiquitination of p53 under conditions where DNA damage has occurred is therefore crucial for preventing the development of cancer, because if cells with severely damaged genomes are not removed from the population, uncontrolled growth can result. However, questions remain about the cellular mechanisms underlying the regulation of p53 stability. In this study, we show that p53-inducible gene 3 (PIG3), which is a transcriptional target of p53, regulates p53 stability. Overexpression of PIG3 stabilized both endogenous and transfected wild-type p53, whereas a knockdown of PIG3 lead to a reduction in both endogenous and UV-induced p53 levels in p53-proficient human cancer cells. Using both in vivo and in vitro ubiquitination assays, we found that PIG3 suppressed both ubiquitination- and MDM2-dependent proteasomal degradation of p53. Notably, we demonstrate that PIG3 interacts directly with MDM2 and promoted MDM2 ubiquitination. Moreover, elimination of endogenous PIG3 in p53-proficient HCT116 cells decreased p53 phosphorylation in response to UV irradiation. These results suggest an important role for PIG3 in regulating intracellular p53 levels through the inhibition of p53 ubiquitination.