• The Journal of Natural Sciences
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• v.9 no.1
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• pp.45-52
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• 1997

We have examined the effects of low concentrations of MNNG, alkylating agent, in survival and mutagenesis in Aspergillus nidulans. Pretreatments of cells with nontoxic and submutagenic doses of MNNG did not reduce the cytotoxic and mutagenic effects of exposure to a high concentration of drug. The results imply that adaptive responses on survival and mutagenesis for MNNG treatments do not occur in Aspergillus nidulans. In the first mitotic cell cycle during germination, the sensitivity to MNNG has been investigated at hourly time interval, and compared with that for UV irradiation. In both UV and MNNG treatments, the sensitivity increased till S cell stage, and decreased while DNA replication continued. Different from that show for UV irradiation, lethality to MNNG reached to the maximum at G2 cell stage.

• Journal of Microbiology
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• v.37 no.1
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• pp.27-34
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• 1999

Two fractions with unusual antifungal activity that suppress asexual sporulation of several fungi were obtained from culture filtrate of Pseudomonas aeruginosa and were partially purified through the repeated silicagel flash column chromatographies. The sporulation-suppressive actions of these fractions in Aspergillus nidulans, Rhizopus stolonifer, and Coprinus cinereus, were analyzed by light and electron microscopes. The germination ability of the spores produced in the presence of these fractions were also checked to determine the persistent effects of these antifungal substances on the next generation. Light microscopic observation of developing sporangia of R. stolonifer grown in the presence of both fractions revealed that the significant number of sporangia failed to reach maturity, and frequently, uncontrolled growths of hyphae and rhizoids from the sporangiophores were found. In A. nidulans addition of these fractions appeared to cause different classes of morphological abnormality in conidia development, which included aborted formation of conidiogenous cells from the apex of conidiophores and enhanced hyphal growths either at the tip or middle of the conidiophores. Germination abilities of spores obtained from the cultures grown in the presence of antifungal fractions were 40∼60% in Aspergillus, 50∼80% in Coprinus (thallic spores), and 30∼40% in Rhizopus compared to those of normal spores.

• Korean Journal of Microbiology
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• v.16 no.3
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• pp.111-121
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• 1978

About 40 temperature-sensitive mutants have been isolated as a preliminary step to study the spore germination, the cell cycle, and the control of macromolecular synthesis in Aspergillus nidulans. To obtain temperature-sensitive mutants rapidly and effectively, the selective enrichment method using antifungal antibiotic nystatin was developed. Based on the data which had applied to the concentration of auxotrophic mutants by the earlier investigators, the optimal concentration and the time of treatment at the nonpermissive temeprature were determined as 50 to 100 units per ml and 4.5 hr., respectively. Out of 41 ts mutants assigned to the strain symbol PK, thirteen that seemed to be arrested at the earlystage of spore germination were subjected to the further cytological and genetic analysis. Elght of these mutants are able to form germ tube and five not. Staining with acid fuchsin for the 5PK strains shows that one irreversible mutant, PK6 strain able to form germ tube, accumulate mitotic spindle, being arrested in mitosis. Another PK15 and PK23 strain have more than one intact nucleolus without germ tube formation at the restrictive temperature. the temperature-senstive mutation in PK12 strain, the onlystrain which is able occurred in certain gene specific for the germination of spore. All of the ts markers are recessive and complement each other in heterokaryon between two different ts markers at the restrictive temperature.

• Proceedings of the Microbiological Society of Korea Conference
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• 1998.04a
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• pp.49.2-49.2
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• 1998

• Proceedings of the Microbiological Society of Korea Conference
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• 1999.04a
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• pp.29-37
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• 1999

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.299-307
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• 2018

Samples were collected from planktonic habitats of the fresh and brackish waters in Korea from August 2016 to May 2018. As a result, three genera and nine species were newly recorded in Korea. The unrecorded indigenous genera were Anathece, Chondrocystis and Geminocystis, and nine species were Anabaenopsis arnoldii, Anathece smithii, Chondrocystis dermochroa, Coelosphaerium aerugineum, Eucapsis microscopica, Geminocystis herdmanii, Microcystis panniformis, Synechococcus nidulans and Woronichinia karelica. Anathece smithii, Coelosphaerium aerugineum, Eucapsis microscopica, Microcystis panniformis and Synechococcus nidulans had been reported to inhabit freshwater, but these were found in brackish water in this study. Microcystis panniformis, which is a potential genus for causing green-tide, is taxonomically valuable in Korea.

• Journal of Microbiology
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• v.41 no.1
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• pp.46-51
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• 2003

RAD6 in yeast mediates postreplication DNA repair and is responsible for DNA-damage induced mutations. RAD6 encodes ubiquitin-conjugating enzyme that is well conserved among eukaryotic organisms. However, the molecular targets and consequences of their ubiquitination by Rad6 have remained elusive. In Aspergillus nidulans, a RAD6 homolog has been isolated and shown to be an allele of uvs). We screened a CDNA library to isolate UVSJ-interacting proteins by the yeast two-hybrid system. JIPA was identified as an interactor of UVSJ. Their interaction was confirmed in vitro by a GST-pull down assay. JIPA was also able to interact with mutant UVSJ proteins, UVSJl and the active site cysteine mutant UVSJ-C88A. The N- and the C-terminal regions of UVSJ required for the interaction with UVSH, a RAD18 homolog of yeast which physically interacts with Rad6, were not necessary for the JIPA and UVSJ interactions. About 1.4 kb jipA transcript was detected in Northern analysis and its amount was not significantly increased in response to DNA-damaging agents. A genomic DNA clone of the jipA gene was isolated from a chromosome I specific genomic library by PCR-sib selection. Sequence determination of genomic and cDNA of jipA revealed an ORF of 893 bp interrupted by 2 introns, encoding a putative polypeptide of 262 amino acids. JIPA has 33% amino acid sequence identity to TIP41 of Saccharomyces cerevisiae which negatively regulates the TOR signaling pathway.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.332-337
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• 1994

Under standard condition (Han, et al., 1990: glucose 1%-nitrate 0.1% minimal medium, 30 ml in 9 cm plate, $10^6$ cells of inoculum per plate), wild type of Aspergillus nidulans developed both sexual and asexual organs in ballance, while velA1 mutant developed asexual ones preferentially. Increase of glucose concentration did not significantly affect the asexual sporulation. However, development of sexual organs were largely affected. It was greatly enhanced when favorable nitrogen source, for example, casein hydrolysate was added, which is contrary to the case of Neurospora or Saccharomyces where limitation of N source induces sexual development. On most of moderate C sources asexual development in $velA^+$ strain was largely inhibited except acetate on which only asexual spores were produced, while that in velA1 mutant strain was not affected. Lactose promoted the sexual development even in velA1 mutant indicating that lactose itself or its metabolic intermediate may induce sexual development independent of allelic state of velA gene. On other moderate favorable C sources, glycerol, galactose and ethanol, asexual development was largely inhibited in $velA^+$ strain but not in velA1 mutant strain. Sexual organs were, however, never produced on acetate. These results suggested that asexual development of wild type is largely dependent on C sources and the velA gene is involved in the repression of asexual development in not-enough-grown (non-competent) thalli resulting in preferential progression of sexual development.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.419-423
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• 2013

Three genes, nsdD, nsdC, and veA are known to be necessary for positive regulating sexual development of Aspergillus nidulans. Since the mutants of those genes hardly form fruiting bodies in heterokaryons constructed by cross between two of them, it is difficult to isolate double mutants. In this work, double mutants of ${\Delta}nsdD$ ${\Delta}veA$ and ${\Delta}nsdD$ ${\Delta}nsdC$ were isolated using the characteristic of the nsdD deletion mutant that it could develop mature cleistothecia in hypoxic and low temperature culture condition. According to the phenotypes of double mutants, the nsdD gene controls the apical growth independently with veA or nsdC. Deletion of veA or nsdC was epistatic to nsdD deletion for pigment production. Conidia formation in submerged culture with lactose as sole carbon source was observed in ${\Delta}nsdD$ ${\Delta}nsdC$ double mutant implicating it to be unique phenotype of nsdC deletion.

• The Korean Journal of Mycology
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• v.36 no.2
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• pp.189-195
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• 2008

When a homothallic ascomycete Aspergillus nidulans is exposed to visible light, cleistothecial development is inhibited. The light response of development in A. nidulans implies the existence of delicate regulation process including reception and translocation of light signaling and determination of development. Previously, mutants that could develop cleistothecia even in the presence of relatively intensive visible light were isolated and several complementation groups were identified. A gene that was able to complement the silA98 mutation, which was responsible for preferred cleistothecia development under visible light, was isolated from AMA-NotI genomic library. The silA gene retained in the 4.3 kb recovered genomic library DNA has an open reading frame (ORF) consisted of 2,388 bp nucleotides, interrupted by 3 introns and consequently encoding 795 amino acids. The putative SilA carries a ${Zn_2}{Cys_6}$ binuclear cluster motif at N terminus and shows high amino acid sequence similarity to Aro80p of Saccharomyces cerevisiae. Deletion mutants of silA showed a strong induction of sexual development under visible light, indicating that SilA is involved in the negative regulation of sexual development in response to the light.