• The Korean Journal of Mycology
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• v.22 no.1
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• pp.1-7
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• 1994

Several mutants which never underwent to sexual development(NSD) of Aspergillus nidulans were analyzed genetically and physiologically. They were divided into two groups according to their characterisitics of asexual development after release from aeration block. The mutants in first group proceeded asexual development immediately after removal of aeration block, while those in second group did 10 hours or more later. The NSD mutants were separated into 4 complementation groups, nsdA, nsdB, nsdC and nsdD. The nsdA and nsdD genes were linked to AcrA1 on linkage groupⅡ and pabaA1 on linkage group I, respectively. The mutant alleles were all recessive to wild type allele in heterokayon state. The mutants did not developed cleistothecia on any of carbon sources, except NSD208 which developed cleistothecia on lactose.

• The Korean Journal of Mycology
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• v.41 no.3
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• pp.192-196
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• 2013

Fungal development is largely affected by many environmental factors. In a model filamentous fungus Aspergillus nidulans, asexual development is promoted by exposure of light, presence of salt and non-fermentable sugars. In other hand, sexual development is largely induced by absence of light, fermentable sugars and hypoxic condition. Also, some important genes including veA and nsdD play positive roles in activating sexual development. Here, we reported that the effect of high concentration of $CO_2$ on developmental decision in A. nidulans. When wild-type $veA^+$ strain was cultured in normal condition, sexual and asexual development occurred in balanced manner. However, high concentration of $CO_2$ (~5%) strongly activated sexual development and inhibited asexual development. Furthermore, this $CO_2$ effect was controlled by the veA or nsdD gene. High $CO_2$ culture of $veA^-$ or $nsdD^-$ mutant didn't activate sexual development, suggesting that the activation of sexual development induced by high $CO_2$ cannot overcome the genetic requirement of sexual development such as veA or nsdD. Since 5% $CO_2$ is an important condition for human pathogenic fungi for surviving and adapting in human body, this developmental pattern of A. nidulans affected by $CO_2$ concentration may provide interesting clues for comparative study with human fungal pathogens including Aspergillus fumigatus.

• 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.

• Journal of Microbiology
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• v.34 no.3
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• pp.284-288
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• 1996

Among the bacteria isolated from compost piles of cattle excretion in a pasture located at the suburbs of Chunchon city, Pseudomonas aeruginosa KMCS-1 was selected for the test of antifungal substances produced. Six fractions were separated by silica gel column chromatography, and then the antifungal activity of each fraction was assayed against Escherichia coli, Bacillus subtilis, Candida albicans, Rhizopus sp., Aspergillus nidulans, Coprinus cinereus, and Pyricularia oryzae by paper disc method. Two fractions showed significant suppressive activities against A. nidulans, C. cinereus, and P. oryzae however, their mycelial growth was not affected by neither of these fractions. Inhibitory activities of these fractions to sporulation was assayed at the concentration of 50. 25, 12. 5, and 6.25 $\mu$g/ml and the average inhibition rates against sporulation of A. nidulans, C. cinereus, and P. oryzae were 94.0, 98.3, and 77.9%, respectively. Further purification and analysis of active substances are now being conducted.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.50-58
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• 1996

Interspecific hybrids between Aspergillus oryzae var oryzae and A. nidulans 514 were obtained by nuclear transfer technique. Several autotrophic mutants isolated from conidiospores of the two strains were mutagenized with ultraviolet and N-methyl-N-nitrosoguanidine. Optimal conditions for formation of intergeneric hybrids were investigated. Frequencies of hybrid formation by nuclear transfer were $3{\times}10^{-5}{\sim}1{\times}10^{-5}$. From observation of genetic stability, conidial size, DNA content, and nuclear stain, it was suggested that their karyptypes are aneuploid. The hybrids showed 1.1~1.4 fold higher xylanase activities than parental strains did. The xylanase of Aspergiilus sp. TAVD514-3 was purified and some of it's enzymatc characteristics were investigated. The enzyme was purified about 85 fold with an overall yield of 17% from the culture medium by ammonium sulfate fractionation, Sephadex G-75 gel permeation chromatography, and CM-sephadex A-50 ion exchange chromatography. The purified enzyme functions optimally at pH 9.0 and 80$^{\circ}C$. The enzymatic activity was increased by the presence of $Mg^{2+}$ and $Mn^2$ ions.

• The Korean Journal of Mycology
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• v.16 no.1
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• pp.26-32
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• 1988

A total of 1,192 patients, who complained a continued chronic cough, suptum or occasional hemoptysis, in spite of successful completion of antituberculous chemotherapy or had some suspected fungal infection, were included. Serum specimens were collected from all the patients studied and sputum or other specimens collected and cultured from the most of the patients. 405(34.0%) cases of the total patients studied showed a positive precipitin reaction to the one or more of the fungal antigens on immunodiffusion tests and 303 cases of them were found to have been infected with Aspergilli, of which Aspergillus fumigatus was involved in 287 cases, followed by Aspergillus flavus(1.7%), Aspergillus nidulans(0.3%), Aspergillus niger(0.3%) and Aspergillus nidulans var. latus(0.1%). pricipitin antibodies were produced to Candida al­bicans(8.1%) and Pseudallerscheria boydii(0.8%). In the chest radiographs of 186 precipitin positive patients, distinct fungus ball shadows were seen in 47 cases and 45 cases of them were formed by A. fumigatus. The isolates from sputum specimens of 724 patients were aspergilli which were consisted of the 46.4% of the total fungal isolates. Identification of 137 yeast like fungi from the sputum specimens of 413 patients revealed that C. albicans(64.2%) was a commonest yeast flora.

• Journal of Microbiology
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• v.41 no.3
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• pp.259-261
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• 2003

The nsdD gene has been predicted to encode a GATA type transcription factor with the type IVb zinc finger DNA binding domain functions in activating sexual development of A. nidulans. In several allelic mutants of nsdD producing truncated NsdD polypeptides lacking the C-terminal zinc finger, the transcription level of nsdD gene was greatly increased. Also in an over-expressed mutant, the transcription under its own promoter was reduced. These results suggest that the expression of nsdD is negatively autoregulated. When the nsdD gene was over-expressed, cleistothecia were formed in excess amounts even in the presence of 0.6 M KC1 that inhibited sexual development of the wild type. Northern blot analysis revealed that the expression of nsdD was repressed by 0.6 M KC1. These results strongly suggest that the inhibition of sexual development by salts was carried out via the nsdD involved regulatory network.

• Microbiology and Biotechnology Letters
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• v.6 no.2
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• pp.59-63
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• 1978

The Screening of fungi producing naringinase was done. A strain of Aspergillus midulans showed the highest naringinase activity among 447 strains those were isolated from soil, spoiled citrus friuts and stock cultures. The cultural Conditions of Asp. nidulans for production of naringinase were studied. A strain of Asp. nidulans showed higher activity when it was cultivated at 30$^{\circ}C$ for 3 days on wheat bran media supplemented with 2.0％ naringin, 0.2％ (NH$_4$)$_2$ SO$_4$ and 0.2％ CaCO$_3$.

• The Korean Journal of Mycology
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• v.45 no.3
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• pp.196-211
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• 2017

Despite the significance of external environmental factors in differentiation, putative factors involved in differentiation of Aspergillus nidulans have not yet been fully understood. A sporulation-specific proteome analysis of A. nidulans in the present study revealed that the expression levels of more than 2,400 proteins were affected under conditions inducing sporulation (0.6 M KCl) compared with normal conditions. Among the proteins with predicted functions, two targets, AN1342 and AN9419, were functionally analyzed using targeted deletion strains and phenotypic observations. For AN1342, because the deletion of the corresponding open reading frame caused a reduction in stalk length during asexual development and in pigment production in liquid culture, the gene was designated as sspA ($\underline{s}hort$ $\underline{s}talk$ & $\underline{p}igment$). Deletion of the AN9419 gene, which is predicted to encode alanyl-tRNA synthetase, led to severe growth defects due to alanine auxotrophy and abolishment of asexual reproduction and thus, the gene was designated as alaA.

• Korean Journal of Microbiology
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• v.23 no.1
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• pp.34-42
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• 1985

From Aspergillus nidulans FGSC 168, mutant strains (TCD27, NCN14, and ACN3) were obtained by NTG and 4-NQO treatments. These four mutant strains were unable to grow on medium supplemented with CMC as a sole carbon source and showed lower levels of CMCase activity in comparison with FGSC168. Some characteristics of these four mutant strains in CMCase production were examined. It was appeared that the permeases for CMCase inducer in all the four mutants were not affected. Two mutants, TCD27 and NCN2, might have some defects in regulatory gene for CMCase production. Analyses of enzyme components of CMCase showed that ACN14 might by defective in structural gene for CMCase.