Cell transformation of established human cell line induced by SV-40 DNA

In the present experiment, it has been noted that clonizing epithelial-like cells of the intestine 407 were more susceptible to SV-40 virus than normal fibroblasts in primary human cell cultures. In the early stage of the infection the cell growth was enhanced by the inoculation of DNA virus but many cells died, showing lysis characterized by CPE, clumping of chromatin and formation of inclusion bodies. On the other hand, the cells surviving infection have given rise to virus-free long term cultures and cellular responses to the virus characterized by cell proliferation which is. classified in four phases. (Phase. I: infection and cell alteration. Phase. II: crisis. Phase. III: fibro-reticulum cell formation. Phase. IV: recovery and proliferation). The most remarkable morphological characteristic was fibroblastic cell alteration from epithelial cells at 5 weeks of virus inoculation. By this study an interesting generalization of human epithelial-like cells can be made about the differentiation of the transformed cells in relation to SV-40 virus and it has been shown that an established human cell line is still susceptible to the reverting action of the SV-40 virus.</p

Oncogenic properties of nucleic acid derived from SV-40 virus

The present report describes the findings on the infectivity of DNA partially purified from SV-40 which was propagated in the monkey kidney cells (BSC-1) in vitro and the importance of nucleic acids as oncogenic factors, particularly the induction of tumor by DNA in newborn hamsters. 593 newborn hamsters in total were used in the present experiments, and cannibalism among them posed as a serious problem. On 30 days postinoculation, very remarkable changes occurred in the liver, lung and subcutaneous areas. Cellular responses of the perivascular cells were predominant. and they were distributed in the interstitial tissues of the liver (liver cirrhosis in primates) and lung. Three hamsters of those subcutaneously inoculated with nucleic acids developed tumors and two tumors appeared in the subcutaneous tissues on 130 days postinoculation, which were identified to be the ones induced by intact SV-40 virus. Other tumors appeared in the liver, lung, intestinal ducts and abdominal surface at 126 days after subcutaneous injection. The cytological observations revealed multiple hemangiosarcoma combined with proliferation of the perivascular cells. On the other hand, cellular responses to nucleic acids were more marked by inoculation of the cell-free filtrate of BSC-1 infected by DNA than of DNA, and essential histologic findings were similar to the respo.nse to infectious DNA. Thirty-nine hamsters (30 per cent) developed tumor within about 200 days postinoculation of the filtrates. Sarcomas were common and they were confined to the subcutaneous tissues in 35 hamsters and to the peritoneum in two others by subcutaneous inoculation of the filtrates. The intestinal gland-cell carcinomas, however, could be induced at 37 and 59 days postinoculation in two hamsters of one litter (7 newborn hamsters) and in the other three newborn hamsters subcutaneous sarcomas were induced by inoculation of the same agent. These results suggest that the observation on the oncogenic capacity of nucleic acids would give us a clue to resolve the course of cancer from the view point of the infectious nucleic acid.</p

Specific antigen of tumor cell transformed by DNA extracted from SV-40 virus

In the immunofluorescent study it has been revealed that rabbit sera immunized with transformed cells induced by SV-40 DNA, produce circulating antibody capable of re:lcting with intranuclear antigens synthesized by SV-40 complyte virus transforming process, In addition, the result confirmed that SV-40 DNA replicates DNA-containing viruses in the host cell and that also the genome coding for the synthesis of SV-40 tumor antigen is resposible for viral DNA.</p

Impacts of reduction of deep levels and surface passivation on carrier lifetimes in p-type 4H-SiC epilayers

Impacts of reduction of deep levels and surface passivation on carrier lifetimes in p-type 4H-SiC epilayers are investigated. The authors reported that the carrier lifetime in n-type epilayers increased by reduction of deep levels through thermal oxidation and thermal annealing. However, the carrier lifetimes in p-type epilayers were not significantly enhanced. In this study, in order to investigate the influence of surface passivation on the carrier lifetimes, the epilayer surface was passivated by different oxidation techniques. While the improvement of the carrier lifetime in n-type epilayers was small, the carrier lifetime in p-type epilayers were remarkably improved by appropriate surface passivation. For instance, the carrier lifetime was improved from 1.4 μs to 2.6 μs by passivation with deposited SiO2 annealed in NO. From these results, it was revealed that surface recombination is a limiting factor of carrier lifetimes in p-type 4H-SiC epilayers

パーティクル・ボードに関する研究 : (第6報)含脂率およびパーティクル・ディメンションが低比重ボードの材質におよぼす影響について

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました

Site-specific biotinylation of RNA molecules by transcription using unnatural base pairs

Direct site-specific biotinylation of RNA molecules was achieved by specific transcription mediated by unnatural base pairs. Unnatural base pairs between 2-amino-6-(2-thienyl)purine (denoted by s) and 2-oxo(1H)pyridine (denoted by y), or 2-amino-6-(2-thiazolyl)purine (denoted as v) and y specifically function in T7 transcription. Using these unnatural base pairs, the substrate of biotinylated-y (Bio-yTP) was selectively incorporated into RNA, opposite s or v in the DNA templates, by T7 RNA polymerase. This method was applied to the immobilization of an RNA aptamer on sensor chips, and the aptamer accurately recognized its target protein. This direct site-specific biotinylation will provide a tool for RNA-based biotechnologies

Geometrical and band-structure effects on phonon-limited hole mobility in rectangular cross-sectional germanium nanowires

We calculated the phonon-limited hole mobility in rectangular cross-sectional [001], [110], [111], and [112]-oriented germanium nanowires, and the hole transport characteristics were investigated. A tight-binding approximation was used for holes, and phonons were described by a valence force field model. Then, scattering probability of holes by phonons was calculated taking account of hole-phonon interaction atomistically, and the linearized Boltzmann's transport equation was solved to calculate the hole mobility at low longitudinal field. The dependence of the hole mobility on nanowire geometry was analyzed in terms of the valence band structure of germanium nanowires, and it was found that the dependence was qualitatively reproduced by considering an average effective mass and the density of states of holes. The calculation revealed that [110] germanium nanowires with large height along the [001] direction show high hole mobility. Germanium nanowires with this geometry are also expected to exhibit high electron mobility in our previous work, and thus they are promising for complementary metal-oxide-semiconductor (CMOS) applications