RESUMO
This study focused on finding a novel sensitive method to determine the methylation modification at DNA dam (GATC) sites in Escherichia coli. A new plasmid which contained three GATC sites recognized by restriction enzyme BclI and one GAATTC site recognized by EcoRI was transformed into E. coli stains AB1157 (dam+) and GM2929 (dam-) respectively. Then the plasmid DNA was digested by restriction enzyme Bdl (T*GATCA), which was sensitive to methylation. The results showed that the plasmid derived from AB1157 was not digested while that from GM2929 was, for the methylation level of the former was high while the latter was low. So by detecting the methylation of plasmid transferred into the strain, we could determine whether methylation existed at DNA dam (GATC) site in E. coli. This method was effective and rapid; moreover, the digested fragments were not dispersive. It also made a basis for the detection of whether methylation occurred in mode beings by low-energy ion beam.
Assuntos
Metilação de DNA , DNA Bacteriano/metabolismo , Escherichia coli/metabolismo , Escherichia coli/genética , Escherichia coli/efeitos da radiação , Genoma Bacteriano , PlasmídeosRESUMO
Since epidemiologic studies have reported a modestly increased risk of oncogenesis associated with certain electromagnetic fields (EMF), popular media and scientists have raised concerns about possible health hazards of environmental exposure to EMF. Laboratory-based experiments have shown that a variety of biological responses were induced by EMF, although these results were controversial and conflicting. The non-thermal effects of low energy EMF,the possible interaction of EMF with biological system have become focus topics in the biolectromagnetic fields. This paper focuses on recent studies of static and extremely low frequency electromagnetic fields, especially the interactive mechanism between EMF and cellular membrane and protein kinase signal transduction pathways. The potential genetic toxicity and risk evaluation are also discussed. However, the existence of some positive findings and the limitations in the set of studies suggest a need for more work.
Assuntos
Humanos , Dano ao DNA , Efeitos da Radiação , Campos Eletromagnéticos , Exposição Ambiental , Regulação da Expressão Gênica , Neoplasias Induzidas por RadiaçãoRESUMO
We theoretically study the translocation time and the mean velocity of a long polymer threading a long nanopore on an external electric field. Theoretical method, which explicitly takes into account the nucleation theory, is presented based on the built polymer expanded model. We overcame the previous theory's defect which did not consider the real length of the pore. The present model implies that the length scale of a pore plays a very important role in the process of polymer translocation. Our calculation results are in agreement with those of previous experiments.
Assuntos
Biopolímeros/química , Biopolímeros/efeitos da radiação , Campos Eletromagnéticos , Eletroporação/métodos , Membranas Artificiais , Modelos Químicos , Nanoestruturas/química , Simulação por Computador , Microfluídica/métodos , Movimento (Física) , Nanoestruturas/efeitos da radiação , PorosidadeRESUMO
A high-yield arachidonic acid producing strain (mortierella alpina) was selected with ion implantation. After treating the dry-thallus of high-yield arachidonic acid-producing strain with BF3-CH3CH solution, the fatty acid in dry-thallus of arachidonic acid producing strain were analyzed by gas chromatography and mass spectrometry. The result showed that there were saturated and unsaturated fatty acids in the dry-thallus. The relative content of arachidonic acid is 70.2% in the all fatty acids. In addition, there were oleic acid, linoleic acid and γ-linolenic acid in the dry-thallus.
