• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.61-61
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• 2003

We have cloned the CGR1 gene encoding glutathione reductase (GR) which catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) from Candida albicans. The cgr1/cgr1 mutants were not viable when CaMAL2 promoter repressed the CGR1 expression. The growth of the mutants could be partially overcome by thiol compounds such as GSH, dithiothreitol, cysteine, N-acetylcysteine and GSSG. Interestingly, C. albicans with CGR1 overexpressed showed defective hyphal growth on solid medium and attenuated virulence. We have also cloned the GCS1 gene encoding ${\gamma}$-glutamylcysteine synthetase which catalyzes the first step of glutathione biosynthesis. The gcs1/gcs1 mutants were nonviable in minimal defined medium. The growth of the mutants could be resumed by supplementing with GSH, GSSG and ${\gamma}$-glutamylcysteine in the medium. The mutants had increased intracellular D-erythroascorbic acid level up to 2.25-fold when transferred to GSH-free medium. When the mutants were depleted of GSH, they showed typical markers of apoptosis. In conclusion, these results suggest that glutathione is an essential metabolite, and involved in hyphal growth, virulence and apoptosis in C. albicans.

• 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.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.1
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• pp.5-10
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• 2005

This experiment was conducted to clarify the functions of supernodulating characters on seed yield determination through the comparison of agricultural traits of supernodulating soybean mutants, Sakukei4, SS2-2, and their parent cultivars, Enrei and Shinpaldalkong2. The plant dry weights of supernodulating mutants, Sakukei4 and SS2-2, were $52\%$ and $61\%$ of their wild type parents at full seed stage (R6). However, the relative growth rate (RGR) from the pod set stage (R3) to R6 of Sakukei4 was 0.022 g/g/day and that of SS2-2 was 0.016 g/g/day, which were higher than those of their parents. Nodule number and dry weight were increased in two supernodulating mutants by the R6 stage. The nitrogen concentrations of leaf, petiole and stem of Sakukei4 were higher than those of Enrei. SS2-2 showed higher nitrogen concentration in petiole than Shinpaldalkong2 had. The positive correlations were appeared between nodule dry weight, plant dry weight and pod number, in two supernodulating mutants during the period from R3 to R6 stage. Although all of the yield components and seed yield were lower in two supernodulating mutants than their parents at the stage of full maturity (R8), the harvest index was higher in supernodulating mutants. The increasing rates of pod number to stem dry weight in two supernodulating mutants showed the higher than those of two their parents at R8 stage. In conclusion, the relative growth rates during the early to the middle reproductive growth period were higher in supernodulating mutants than the wild types. This could be resulted in an increase in pod number. The increase of relative growth rate was the result of the successive supplement of nitrogen source from biological nitrogen fixation (BNF) of nodules during the middle reproductive growth period in supernodulating mutants.

• The Plant Pathology Journal
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• v.18 no.4
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• pp.179-186
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• 2002

Four newly developed cotton mutants (M-111, M-7662, M-358 and M-218) were compared for their resistance against Cotton leaf curl virus(CLCuV) together with commercial resistant (CIM-443, CIM-482, CIM-473, FH-900 and FH-901) and susceptible (5-12) varieties by artificial inoculation through grafting and under natural field conditions. Infectivity and success of grafting were 100% in all cases. None of the grafted plants were found immune or asymptomatic. All the grafted mutants and most of their single plant progeny rows (SPPRs) showed highly resistant responses as the symptoms displayed by these mutants were milder than the commercial cultivars. Grafted mutants also had delayed disease reactions as they took more time (25-30 days) to produce disease symptoms, as compared with resistant commercial varieties that produced disease 18-22 days after inoculation. Growth of the grafted SPPRs of tested mutants was normal, which is an indication that there will be no production losses. Observations under natural infestation of whitefly showed that two SPPRs of M-ll/CE and M-7662-1/2 and one resistant variety CIM-443 exhibited slight incidence of disease, while one SPPR of M-l1/59 and S-12 were moderately susceptible and highly susceptible with 21％ and 97.l％ disease incidence, respectively. This study also showed that plants displaying more disease symptoms through grafting were easily infected under natural conditions. These results suggest that preference should be given to those plants that exhibited highly resistant responses after artificial inoculation.

• Journal of Crop Science and Biotechnology
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• v.11 no.2
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• pp.111-118
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• 2008

Soybean is sensitive to waterlogging stress, leading to reduce their growth and yield significantly. The objective of this study was to characterize the relative sensitivities of biomass accumulation and specific nodule activity under waterlogging stress between supernoduating mutants, 'SS2-2' and 'Sakukei 4' and their wild-type soybeans, 'Sinpaldalkong 2' and 'Enrei', respectively. Flooding treatment was performed to soybean plants grown in a pot by waterlogging for 15 days from the beginning bloom(R1) stage under natural light. The nodule number and weight were considerably decreased by waterlogging stress. The bleeding sap rate of waterlogging soybean plants was decreased by 78-80% in supernodulating mutants and 65-74% in their wild types compared to control plants. The relative ureide-N content was also decreased by waterlogging and the reduction was high in supernodulating mutants. This may cause the massive reduction of shoot and root dry weight and leaf area in waterlogged soybean plants. There was a varietal difference in response to the waterlogging stress. During the waterlogging, supernodulating mutants maintained higher spad value than their wild types. Particularly, the difference between soybean varieties was clear in low rank leaves from the top. Also, supernodulating mutants showed a weak waterlogging tolerance than their wild types. Under waterlogging conditions, massive nodules were considerably destroyed and specific nodule activity after waterlogging may not be recovered when compared to their wild-type soybeans. Supernodulating mutants showed lower seed yield than their wild types in waterlogging conditions.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.203-208
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• 1985

Partial characterization of B. thuringiensis var. kurstaki 3ab temperature-sensitive mutants was carried out through biochemical analyses, utilization tests of carbohydrate sources, antobiotic resistant test, hemolytic reaction test, growth measurement of Fructus gardenia sxtrant medium and toxicity test against mice. Six ts mutants, ts-U154, ts-U601, ts-U602, ts-U603, tsU-604, and ts-U788 could not produce urease, ts-U603 lost its motility, ts-U154 could not use salicin and cellobiose and ts-U603 not ribose. All ts mutants except ts-U154 and wild type strain were resistant to cephalothin, ampicillin, and penicillin. but ts-U154 was sensitive to the three. Four mutants, ts-U21, ts-U74, ts0U131 and ts-U154 did not form pigment colonies on the F. gardenia medium. All the mutants and wild type strain showed hemolysis reaction on the blood agar. The B. thuringiensis and mutants were not toxic to mice.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.98-105
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• 1986

Rhizobium meliloti 102 F 51, the symbiotic partner of alfalfa, was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) and UV-irradiation. Three group of mutants which form white, white-pink and red nodules were selected. The adetylene reduction activity, nodulation activity, amount of heme synthesis during the nodulation, and ${\delta}-aminolevulinic$ acid synthetase (ALAS) and ${\delta}-aminolevulinic$ acid dehydratase (ALAD) activities in free living rhizobia and bacteroid states of the each group of mutants were compared. The mutants forming white nodules showed lower acetylene reduction activity compared to those of red nodule forming mutants. The two key enzymes for the heme synthetic pathway, ALAS and ALAD activities of the mutants forming red nodules was much higher than those of the mutants forming white nodules in bacteroid state, however no significant difference was observed in free living state. In the nodules the ALAS was detected only in bacteroid fraction, while ALAD was detected both in bacteroid and plant fraction. ALAS was dramatically increased with the heme synthesis during the nodulation, while ALAD was decreased in plant fraction but slight increase was observed in bacteroid fraction.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.43-51
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• 1998

Studies were carried out to investigate phenotypic expression, mortality and biochemical analysis of haemolymph proteins of nm-d, nm-f, nm-k and nmn bib-molting mutants of the silkworm, Bombyx mori. The non-molting mutants characters were expressed in the homozygote of each mutant genes. All strains of non-molting mutants were similar with each other in physiological characteristics, but the expression varied with each strains. The larvae of nm-d, nm-i and nmn died between day 5 and day 9 after hatching without the first molt. The nm-f and nm-k mutants died between day 5 and day 16 with a slight increase of body weight and, more than 90% of the mutants larvae died before the first molt and a few of them survived to the 2nd and the 3rd instar and died. The haemolymph protein components of nm-d, nm-i, and nmn were rapidly reduced, and on the other hand those of nm-f and nm-k consistently until they died. And there were no distinguishable difference in haemolymph components of non-molting mutants, as compared to those normals.

• BMB Reports
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• v.37 no.2
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• pp.153-158
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• 2004

The acid-labile subunit (ALS) is known to interact with the IGF binding protein (IGFBP) in the presence of insulin-like growth factors (IGFs). Studies, however, indicate that ALS forms a doublet with IGFBP3, independent of IGFs. To characterize the structural domain required for the IGF-free ALS-IGFBP3 interaction, seven recombinant human IGFBP3 mutants were generated: three deletion mutants and four site-specific mutants that had altering N-terminal regions of IGFBP3. ALS and IGFBP3 mRNAs were co-injected into Xenopus oocytes, and their products were cross-linked and immunoprecipitated using antisera against ALS or IGFBP3. Among the deletion mutants, the mutant of D40 (deleted in 11-40th amino acids) exerted no effect in the interaction with ALS, while D60 (${\Delta}11$-60) demonstrated a moderate reduction. D88 (${\Delta}11$-88), however, showed a significant decrease. In the case of site-specific mutants, the mutation that alterated the IGF binding site (codons 56 or 80) exerted a significant reduction in the interaction, whereas codons 72 or 87 showed no significant change in the interaction with ALS. The stability of the ALS-IGFBP3 interaction was analyzed according to a time-dependent mode. Consistent with the binding study, mutants on the IGF binding sites (56 or 80) consistently show a weakness in the ALS-IGFBP3 interaction when compared to the mutants that covered the non-IGF binding sites (72 or 87). This study suggests that the N-terminal of IGFBP3, especially the IGF binding site, plays an important role in interacting with ALS as well as in stabilizing the dual complex, independent of IGFs.