abstract
We isolated nickel-resistant bacterium from soil in order to identify a novel nickel resistance determinant. Using 16S rRNA gene sequencing, an isolate was identified as Enterobacter sp. ...Ni15. This species showed a medium-level (resistant to up to 10 mM) nickel resistance in nutrient-rich media. Enterobacter sp. Ni15 has a novel plasmid, pNi15, and an increased nickel resistance to Escherichia coli DH5αin trans. To isolate the nickel resistance gene from pNi15, the plasmid was digested with XbaI and its fragments were cloned into pBluescriptIISK(+). The clones were transferred into E. coli DH5α. The nickel resistance of the clones was then assayed. From these results, a pNi15100 isolate containing a 5328 bp XbaI fragment of pNi15 was identified and sequenced. The E. coli DH5α harboring the pNi15100 showed a resistance to up to 7 mM nickel. Using a subcloning analysis, we were able to identify the novel nickel resistance determinant: the nrp gene encoding the putative proteins NrpA and NrpB.
The global RNA transcription profiles of Bacillus lentimorbus WJ5 under an in vitro co-culture with Colletotrichum gloeosporioides were analyzed in order to study the antagonistic bacteria-fungi ...interactions. Using a filter membrane system, B. lentimorbus WJ5 was exposed to the spores of C. gloeosporioides at the late exponential stage. The transcription profiles of the B. lentimorbus WJ5, both with and without a challenge from C. gloeosporioides, were analyzed using custom DNA chips containing 2,000 genome fragments. A total of 337 genes were expressed, with 87 and 47 up- and down-regulated, respectively. Of these, 12 genes, which were involved in central carbon metabolisms, and 7 from minor catabolism were relatively highly up-regulated (> 10 fold) and down-regulated (< 0.2 fold), respectively. Nine genes, which were thought to be related to the antifungal activity, were also up-regulated, but their levels were not so high (2.0 - 9.7 folds). From the results, during the early stage of the co-culture of B. lentimorbus WJ5 and C. gloeosporioides, nutrient competition seemed to occur; therefore, the genes from central carbon metabolisms could be up-regulated, while those from minor catabolism could be down-regulated.
O
6-methylguanine-DNA methyltransferase (O
6-MGMT; EC 2.1.1.63) is a key repair enzyme that helps to protect the cell against alkylation on DNA by removing a methyl group from the O
6-position of ...guanine. Here, we cloned and sequenced the full-length
O
6
-MGMT cDNA from the hermaphroditic fish,
Kryptolebias marmoratus. Complete
Km-O
6
-MGMT cDNA was 1324
bp in length, and the open reading frame of 567
bp encoded a polypeptide of 188 amino acid residues. Phylogenetic analysis revealed that
Km-O
6
-MGMT was clustered with those of other fish species. Embryo, juveniles, and aged secondary fish had low levels of
Km-O
6
-MGMT mRNA than adults, indicating more susceptibility to DNA damage by alkylating agent exposure during these developmental stages.
Km-O
6
-MGMT mRNA levels differed according to tissue type and was highest in the liver. Exposure to an alkylating agent,
N-methyl-
N-nitrosourea (MNU) exposure increased the mRNA expression of tumor suppressor gene such as
p53 and oncogenes such as
R-ras1,
R-ras3,
N-ras,
c-fos as well as
Km-O
6
-MGMT mRNA in a time-dependent manner. On the contrary, several (anti)estrogenic compounds (17β-estradiol 100
ng/L, tamoxifen 10
μg/L, bisphenol A 600
μg/L, and 4-
tert-octylphenol 300
μg/L) suppressed mRNA expression of
Km-O
6
-MGMT in most tissues, especially the liver. In juvenile fish, 17β-estradiol, bisphenol A, and 4-
tert-octylphenol also decreased the expression of
Km-O
6
-MGMT mRNA in a time-dependent manner. Overall, our finding shows that
Km-O
6
-MGMT mRNA levels can be modulated by environmental estrogenic compounds as well as alkylating agents. This finding will be helpful to improve our knowledge of the effects of estrogenic compounds that contain the genotoxic ability to inhibit the DNA repair process in aquatic animals.
In the self‐fertilizing hermaphroditic fish, Rivulus marmoratus, the susceptibility to tumor induction by N‐methyl‐N‐nitro‐N‐nitrosoguanidine(MNNG) was evaluated. Seven‐day‐old fish larvaewere ...exposed for 2 h toMNNG at concentrations ranging from 5 to 25 ppm in a static water bath. The exposed fish were observed at 2 and 4 monthsafter carcinogen treatmentto assess tumor development. Within 4‐ months after25 ppmMNNG exposure, nearly all fish developed thyroid tumors. The tumor incidenceswere dose‐ and time‐dependent, and the latent period of tumor induction was less than 2 months. Most induced neoplasms were papillary carcinomas similar histologically to those of rodents and humans, and the tumors were serially transplantable to other fish of the same species. These results demonstratethat rivulus could be useful as a model of thyroid carcinogenesis.
O⁶-methylguanine-DNA methyltransferase (O⁶-MGMT; EC 2.1.1.63) is a key repair enzyme that helps to protect the cell against alkylation on DNA by removing a methyl group from the O⁶-position of ...guanine. Here, we cloned and sequenced the full-length O⁶-MGMT cDNA from the hermaphroditic fish, Kryptolebias marmoratus. Complete Km-O⁶-MGMT cDNA was 1324bp in length, and the open reading frame of 567bp encoded a polypeptide of 188 amino acid residues. Phylogenetic analysis revealed that Km-O⁶-MGMT was clustered with those of other fish species. Embryo, juveniles, and aged secondary fish had low levels of Km-O⁶-MGMT mRNA than adults, indicating more susceptibility to DNA damage by alkylating agent exposure during these developmental stages. Km-O⁶-MGMT mRNA levels differed according to tissue type and was highest in the liver. Exposure to an alkylating agent, N-methyl-N-nitrosourea (MNU) exposure increased the mRNA expression of tumor suppressor gene such as p53 and oncogenes such as R-ras1, R-ras3, N-ras, c-fos as well as Km-O⁶-MGMT mRNA in a time-dependent manner. On the contrary, several (anti)estrogenic compounds (17β-estradiol 100ng/L, tamoxifen 10μg/L, bisphenol A 600μg/L, and 4-tert-octylphenol 300μg/L) suppressed mRNA expression of Km-O⁶-MGMT in most tissues, especially the liver. In juvenile fish, 17β-estradiol, bisphenol A, and 4-tert-octylphenol also decreased the expression of Km-O⁶-MGMT mRNA in a time-dependent manner. Overall, our finding shows that Km-O⁶-MGMT mRNA levels can be modulated by environmental estrogenic compounds as well as alkylating agents. This finding will be helpful to improve our knowledge of the effects of estrogenic compounds that contain the genotoxic ability to inhibit the DNA repair process in aquatic animals.
O super(6)-methylguanine-DNA methyltransferase (O super(6)-MGMT; EC 2.1.1.63) is a key repair enzyme that helps to protect the cell against alkylation on DNA by removing a methyl group from the O ...super(6)-position of guanine. Here, we cloned and sequenced the full-length O super(6)-MGMT cDNA from the hermaphroditic fish, Kryptolebias marmoratus. Complete Km-O super(6)-MGMT cDNA was 1324 bp in length, and the open reading frame of 567 bp encoded a polypeptide of 188 amino acid residues. Phylogenetic analysis revealed that Km-O super(6)-MGMT was clustered with those of other fish species. Embryo, juveniles, and aged secondary fish had low levels of Km-O super(6)-MGMT mRNA than adults, indicating more susceptibility to DNA damage by alkylating agent exposure during these developmental stages. Km-O super(6)-MGMT mRNA levels differed according to tissue type and was highest in the liver. Exposure to an alkylating agent, N-methyl-N-nitrosourea (MNU) exposure increased the mRNA expression of tumor suppressor gene such as p53 and oncogenes such as R-ras1, R-ras3, N-ras, c-fos as well as Km-O super(6)-MGMT mRNA in a time-dependent manner. On the contrary, several (anti)estrogenic compounds (17 beta -estradiol 100 ng/L, tamoxifen 10 mu g/L, bisphenol A 600 mu g/L, and 4-tert-octylphenol 300 mu g/L) suppressed mRNA expression of Km-O super(6)-MGMT in most tissues, especially the liver. In juvenile fish, 17 beta -estradiol, bisphenol A, and 4-tert-octylphenol also decreased the expression of Km-O super(6)-MGMT mRNA in a time-dependent manner. Overall, our finding shows that Km-O super(6)-MGMT mRNA levels can be modulated by environmental estrogenic compounds as well as alkylating agents. This finding will be helpful to improve our knowledge of the effects of estrogenic compounds that contain the genotoxic ability to inhibit the DNA repair process in aquatic animals.
The
Hox genes have been known to be involved in pattern formation during vertebrate development through differential expression along the anteroposterior body axis. Human homologue of ...position-specific regulatory region of murine
Hoxa-7 was cloned from human genomic library. The restriction map of the 18-kb insert was determined, of which a 3.9-kb region was sequenced. Homology plot between the murine and the corresponding human sequence showed high sequence conservation over 70% in several regions. The homologous region has been reduced to about 1.1 kb (
HCR: human control region), which contained several putative factor binding sites. The function of
HCR was analyzed in transgenic mice and turned out to be a position-specific regulatory element of human, setting the precise anterior boundary of expression in transgenic embryos; at day 12.5 post-coitum a distinct anterior limit of expression was noted at the level of C5 in neural tube and spinal ganglia in transgenic embryos. These results indicate that the regulatory sequences as well as the molecular mechanism for
Hox gene expression are highly conserved among vertebrates.
The persistence of pendimethalin in soil and ground water has an injurious effect on ecosystem. Pendimethalin-degrading bacterium was isolated from Masan, Gyeongnam province and temporarily ...identified as Bacillus sp. MS202 by the analysis of API CHB50, kit, FAME, and 16S rDNA sequence. from the analysis of pnedimethalin metabolite using TLC, GC, and GC-MS, we found that the degradation of pendimethalin by Bacillus sp. MS202 did not result in the dealkylated form, but the formation of the reduced compound, 6-amino-2-nitro-N(1-ethylpropyl)-3,4-xylidine or 2- amino-6-nitro-N(1-ethylpropyl)-3,4-xylidine. 토양과 지하수에서 pendimethalin의 지속성은 환경에 해로운 영향을 미친다. 경남 마산에서 분리한 pendimealalin분해 균주는 API CHB50 kit 시험, FAME분석, 그리고 16S rDNA 염기서열분석 결과로 Bacillus sp. MS202로 잠정적으로 동정하였다. TLC, GC, 그리고 GC-MS 분석에 의해 Bacillus sp. MS202가 pendimethalin의 $-NO_2$를 $-NH_2$로 환원시킨다는 것을 알 수 있었다. 이는 일반적으로 알려진 호기성 미생물에 의한 pendimethalin 분해가 탈알킬화가 우선한다는 보고와 상반되는 새로운 결과이다.
To induce the cellulolytic variants of oyster mushroom (Pleurotus ostreatus), basidiospores were irradiated at the dose of $1kGy{\sim}20kGy$ of gamma-ray. After irradiation, activities of ...extracellular enzymes were determined by the method of MUF residue and genetic similarity was observed by RAPD analysis of variants. Three variants of 2KG-1, 2KG-2 and 20KG-1 were clarified as highly cellulolytic isolates. It seemed that the difference of genetic similarity among variants have derived from gamma-ray radiation. It is suggested that 3 cellulolytic variants induced by gamma-ray in this experiment could play a useful role to reuse cellulosic bioresources. 이온화방사선을 이용하여 느타리(Pleurotus ostreatus)의 담자포자(basidiospore)로부터 섬유소 분해능이 뛰어난 변이주를 유도하고자 본 실험을 수행하였다. 담자포자를 감마선조사 후 MUF(4-methylumbelliferyl) 반응기를 이용하여 세포외분비효소의 활성도를 측정하였다. 방사선유기 변이주에서 RAPD(random amplified polymorphic DNA)의 양상을 조사하여 유전유사도를 분석하였다. 검색한 45종의 균주들은 MUF의 기질에 따라 다양한 기질분해도를 보였으며, 이 중에서 섬유소 분해능이 뛰어난 3개의 변이주 2KG-1, 2KG-2와 20KG-1를 선발하였다. RAPD 양상을 통해 조사한 변이주의 유전유사도는 대조군에 대해 $50%{\sim}52%$였고, 변이주간에는 $49%{\sim}57%$로 나타나 방사선조사에 의해 유전적 다양성이 증가되었음을 알 수 있었다. 본 연구에서 방사선조사에 의해 유기된 변이주는 섬유소성 생물폐자원의 재활용에 있어서 매우 유용하게 활용될 수 있을 것으로 기대된다.
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