• 미생물학회지
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• 제24권3호
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• pp.221-227
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• 1986

Aspergillus nidulans에서, UV나 4- NQO에 의한 돌연변이 유발에 있어 성내적으로 핑요한 uvsH돌연변이를 가 지고 있는 변이주를 이용하여 mitotic recombination 현상을 조사하였다. 비록 uvsH locus는 {pB 37과 centromere 사이에서의 자말적인 mitotic crossing over에는 영향플 주지 않았지만 uvsH/uvsH동형이애체에서 UV에 의한 Int te rgenic recombination은 얻어나지 않았다. 또한 서로 상보적이 아닌 riboA 1과 ribo A3 유전핵적 단시에서의 riboflavin에 대한 gene converSlOn에 있어셔 u uvsH 돌연변이는 자말석이든 LV보 유멜시켰던 이 과정에 관여하고 있지 않있다. 비록 정상석인 성 장에서는 거으1 차이가 없였지만, 세포들을 UV로 조사하였을 때 야생주에 비해 uvsH동형 이배체에서의 aneuploid발생이 높은 빈도로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제25권5호
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• pp.598-605
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• 2015

The cohesin complex holds sister chromatids together and prevents premature chromosome segregation until the onset of anaphase. Mcd1 (also known as Scc1), the α-kleisin subunit of cohesin, is a key regulatory subunit of the mitotic cohesin complex and is required for maintaining sister chromatid cohesion, chromosome organization, and DNA repair. We investigated the function of Mcd1 in meiosis by ectopically expressing Mcd1 during early meiotic prophase I in Saccharomyces cerevisiae. Mcd1 partially regulated the progression of meiotic recombination, sister chromatid separation, and nuclear division. DNA physical analysis during meiotic recombination showed that Mcd1 induced double-strand breaks (DSBs) but negatively regulated homologous recombination during DSB repair; Mcd1 expression delayed post-DSB stages, leading to inefficiencies in the DSB-to-joint molecule (JM) transition and subsequent crossover formation. These findings indicate that meiotic cells undergo Mcd1-mediated DSB formation during prophase I, and that residual Mcd1 could regulate the progression of JM formation during meiotic recombination.

• 미생물학회지
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• 제17권3호
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• pp.137-151
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• 1979

Germinating conidia of Aspergillus nidulans diploid heterozygous for color and other genetic markers were used to direct and distinguish genetic events such as mutation, mitotic crossingover and nondisjunction in a single test after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (NG), mitomycin C(MC), and chloral hydrate(CH). The following results were obtained : 1. NG reduced the survival of conidia and increased the frequencies of miototic segregants about sevenfoli over the control ; among the mitotic segregants the predominant genetic event was mitotic crossingover. NG also produced many abnormal colonies, which appeared to be of the types caused by induced semidominant lethals or chromosomal aberrations, and the aneuploid types found spontaneously. 2. After treatment with MC the survival of conidia was reduced but few abnormal colonies were produced. The frequencies of miotic segregants were increased about threefold over the control ; in the mitotic segeregants the induced genetic event was mitotic crossingover. 3. CH gave no apparent effect on the survival of conidia and the frequencies of mitotic segregants. However, CH generated abnormal colonies, very greatly, which turned out to be of the aneuploid types. This result suggests that CH interferes with the normal distribution of chromosomes in mitosis.

• 한국환경성돌연변이발암원학회지
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• 제15권2호
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• pp.100-105
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• 1995

The effects of DNA polymerase $\beta$ on the somatic chromosome mutations and mitotic recombinations were investigated using the transgenic Drosophila beating chimetic gene consisting of a promoter region of Drosophila actin 5C gene and rat DNA polymerase $\beta$. For detecting the somatic chromosome mutations and mitotic recombinations, the heterozygous (mwh/+) strains possessing or lacking transgene poi 13 were used. The spontaneous frequency of small mwh spots, due to deletion or nondisjunction etc., in the non-transgenic w strain and the transgenic p[pol $\beta$]-130 strain was 0.351 and 0.606, respectively. The spontaneous frequency (0.063) of large mwh spots, arises mostly from somatic recombination between the centromere and the locus mwh, in the transgenic p[pol $\beta$]-130 strain was about three times higher than that (0.021) of the non-transgenic w strain. The mutant clone frequencies of small and large mwh spots induced by N-methyl-N'-nitro-N-nitrosoguanidine and ethyl methanesulfonate in the transformant p[pol $\beta$]-130 were higher than those in the host strain w. The present results suggest that rat DNA polymerase $\beta$ participate at least in the somatic chromosome mutations and mitotic recombination processes.

• 한국응용곤충학회지
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• 제35권4호
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• pp.315-320
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• 1996

Drosophila의 actin 5C 유전자 promoter에 쥐의 DNA polymerase $\beta$cDNA를 도입시킨 형질전환 초파리가 고감수성 환경성 변이원 검출계로 사용할 수 있는지를 조사하였다. 체세포 염색체 재조환과 체세포 염색체 돌연변이의 검출을 위해서는 geterozygous(mwh/+) 계통을 사용하였다. 염색체상의 결실이나 비분리 등에 의한 small mwh spot의 자연 발생적 빈도는 non-transgenic w 계통과 transgenic p[pol $\beta$]-130 계통에서 각각 0.351 및 0.606 정도였다. 체세포 염색체 재조환에 의한 large mwh spot의 자연 발생적 빈도의 경우는 transgenic p[pol $\beta$]-130 계통(0.063)이 non-transgenic w 계통(0.021)에 비해 약 3배 정도 높게 나타났다. IQ, Glu-P-1 및 {TEX}$AFB_{1}${/TEX} 등의 돌연변이원의 처리에 의한 경우, 두 종류의 mutant clone의 발생 빈도는 쥐의 DNA polymerase $\beta$가 도입된 transgenic p[pol $\beta$]-130 계통이 non-transgenic w 계통에 비하여 모두 약 2-3배 정도 높게 나타났다. 본 연구의 결과는 쥐의 DNA polymerase $\beta$가 최소한 체세포 염색체 돌연변이 유발이나 체세포 염색체 재조환의 생성 과정에 관여함을 의미하며, 형질전환 초파리 계통이 환경성 변이원 검출계로서 충분한 응용가능성이 있음을 보여 주었다.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.405-411
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• 2017

Homologous recombination occurs between homologous chromosomes and is significantly involved in programmed double-strand break (DSB) repair. Activation of two recombinases, Rad51 and Dmc1, is essential for an interhomolog bias during meiosis. Rad51 participates in both mitotic and meiotic recombination, and its strand exchange activity is regulated by an inhibitory factor during meiosis. Thus, activities of Rad51 and Dmc1 are coordinated to promote homolog bias. It has been reported that Hed1, a meiosis-specific protein in budding yeast, regulates Rad51-dependent recombination activity. Here, we investigated the role of Hed1 in meiotic recombination by ectopic expression of the protein after pre-meiotic replication in Saccharomyces cerevisiae. DNA physical analysis revealed that the overexpression of Hed1 delays the DSB-to-joint molecule (JM) transition and promotes interhomolog JM formation. The study indicates a possible role of Hed1 in controlling the strand exchange activity of Rad51 and, eventually, meiotic crossover formation.

• Journal of Microbiology
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• 제37권4호
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• pp.248-255
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• 1999

We have analyzed the MRE3/REC114 gene of Saccharomyces cerevisiae, previously detected in isolation of mutants defective in meiotic recombination. We cloned the MRE3/REC114 gene by complementation of the meiotic recombination defect and it has been mapped to chormosome XIII. The DNA sequence analysis revealed that the MRE3 gene is identical to the REC114 gene. The upstream region of the MRE3/REC114 gene contains a T_4C site, a URS (upstream repression sequence) and a TR (T-rich) box-like sequence, which reside upstream of many meiotic genes. Coincidentally, northern blot analysis indicated that the three sizes of MRE3/REC114 transcripts, 3.4, 1.4 and 1.2 kb, are induced in meiosis. A less abundant transcript of 1.4 kb is detected in both mitotic and meiotic cells, suggesting that it is needed in mitosis as well as meiosis. To examine the role of the MRE3/REC114 gene, we constructed mre3 disruption mutants. Strains carrying an insertion or null deletion of the MRE3/REC114 gene showed slow growth in nutrient medium and the doubling time of these cells increased approximately by 2-fond compared to the wild-type strain. Moreover, the deletion mutant (${\delta}$mre3) displayed no meiotically induced recombination and no viable spores. The mre3/rec114 spore lethality can be suppressed by spo13, a mutation that causes cells to bypass reductional division. The double-stranded breaks (DSBs) which are involved in initiation of meiotic recombination were not detected in the analysis of meiotic chromosomal DNA from the mre3/rec114 disruptant. From these results we suggest that the MRE3/REC114 gene product is essential in normal growth and in early meiotic stages involved in meiotic recombination.

• Molecules and Cells
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• 제39권7호
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• pp.550-556
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• 2016

During meiosis, exchange of DNA segments occurs between paired homologous chromosomes in order to produce recombinant chromosomes, helping to increase genetic diversity within a species. This genetic exchange process is tightly controlled by the eukaryotic RecA homologs Rad51 and Dmc1, which are involved in strand exchange of meiotic recombination, with Rad51 participating specifically in mitotic recombination. Meiotic recombination requires an interaction between homologous chromosomes to repair programmed double-strand breaks (DSBs). In this study, we investigated the budding yeast meiosis-specific proteins Hop2 and Sae3, which function in the Dmc1-dependent pathway. This pathway mediates the homology searching and strand invasion processes. Mek1 kinase participates in switching meiotic recombination from sister bias to homolog bias after DSB formation. In the absence of Hop2 and Sae3, DSBs were produced normally, but showed defects in the DSB-to-single-end invasion transition mediated by Dmc1 and auxiliary factors, and mutant strains failed to complete proper chromosome segregation. However, in the absence of Mek1 kinase activity, Rad51-dependent recombination progressed via sister bias in the $hop2{\Delta}$ or $sae3{\Delta}$ mutants, even in the presence of Dmc1. Thus, Hop2 and Sae3 actively modulate Dmc1-dependent recombination, effectively progressing homolog bias, a process requiring Mek1 kinase activation.

• 미생물학회지
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• 제31권1호
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• pp.48-53
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• 1993

Saccharomyces distaticus 의 glucoamylase 생성능을 증진시킬 목적으로 STA1 유전자를 YIp vector 를 이용하여 염색체에 도입해 주고자 하였다. STA1 유전자 5.8-Kb 를 YIp vector 에 재조합하여 YIp-STA 를 재작하고, S. diastaticus GMT-11 (a, ura 3, STA1) 을 숙주균주로 하여 염색체의 STA1 유전자 부위에 homologous recombination 되어 삽입하도록 형질전환을 실시하였다. 이렇게 하여 glucoamylase 생성능이 모균주에 비해 최대 6배까지 증대된 다양한 형질전환체들을 얻을 수 있었다. 그리고 glycoamylase 생성능이 증대된 형질전환체들의 염색체 DNA 를 분리하여 Southern hybridization 을 실시한 결과 YIp-STA 가 multi-copy integration 되었음을 확인하였고, 또한 도입해 준 YIp-STA 는 세포분열인 30세대기간 동안 계속되었어도 안정하게 유지되었음을 알았다.

• Journal of Microbiology and Biotechnology
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• 제8권5호
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• pp.441-448
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• 1998

A cellobiose-utilizing recombinant yeast having $\beta$-glucosidase activity was developed for ethanol production from a mixture of glucose and cellobiose. Using $\delta$-sequences of Tyl transposon of yeast as target sites for homologous recombination, a heterologous gene of $\beta$-glucosidase was integrated into the chromosome of Saccharomyces cerevisiae. The $\delta$-integrated recombinant yeast, Saccharomyces cerevisiae L2612 (Pb-BGL), showed perfect mitotic stability even in nonselective media and showed ca. 1.5 fold higher $\beta$-glucosidase activity than the recombinant yeast harboring the $2\mu$-based plasmid vector system. A mathematical model was developed to describe the $\beta$-glucosidase formation and ethanol production from the Saccharomyces cerevisiae L2612 ($p\delta-BGL$). The model newly described that the heterologous $\beta$-glucosidase production mediated by ADH1 promoter is regulated by glucose and repressed by ethanol.