It is well known that DNA methylation is involved in the control of transposable elements in eukaryotic cells. Recent studies indicate that demethylation of DNA in a mutant of Chlamydomonas and Arabidopsis causes transcriptional activation and mobilization of transposons. In this report, transposition of a retrotransposon was investigated in the phytopathogenic fungus Fusarium oxysporum treated with 5-azacytidine (5azaC), a reagent that causes reduction in the DNA methylation level. The results showed elevated transposition frequency in 5azaC-treated isolates when they were incubated for a long time. However, increase of retrotransposon transcripts was not observed, suggesting that the retrotransposon was mobilized by a mechanism other than its transcriptional activation.
Cloning and disruption of fga1, the gene encoding the G protein α subunit FGA1 in phytopathogenic fungus Fusarium oxysporum, has been reported previously, and the fga1 disruptants showed altered colony morphology, increased heat resistance, reduced conidiation and pathogenicity. To further evaluate the role of G protein signaling in this fungus, cloning of fga2, which encodes the second Gα protein FGA2, was performed by PCR methods. The deduced primary structure of FGA2 (355 amino acid residues) showed high identity with other Gα proteins, which belong to class III of fungal Gα proteins. Disruption of fga2 led to higher heat resistance, similar to the fga1 disruptants, but pathogenicity was completely lost, unlike the fga1 disruptants. Alteration of colony morphology and conidiation, which was observed in the fga1 disruptants, was not observed in the fga2 disruptants. The fga1/fga2 double disruptants showed phenotypic alterations similar to the fga1 or fga2 single disruptants, but increase of heat resistance was much more pronounced than in each single disruptant.
Photoinduced electron transfer processes in flavin-porphyrin hetero-type Langmuir-Blodgett films were investigated in terms of the electric-field-induced quenching of flavin fluorescence. The dependence of the fluorescence quenching on the applied voltage corresponded well with the rectifying photocurrent-voltage characteristics. The rate of fluorescence quenching, which is approximately 1 min-1, was found to be slow. It was concluded that the fluorescence quenching was attributed to reduced flavin molecules in the flavin monolayers generated by the electron transport process after the charge separation.
This paper shows a new test coverage criterion for extended finite state machine to comprehensively test the combination of state transitions and accompanying actions in software.Our criterion requires that (i) test cases cover all the successive state transition sequences of specified length, and also (ii) the test cases cover all the paths on control flow graphs of actions that accompany each of the successive state transition sequences.(i) and (ii) are the characteristics of N-switch and all-path test coverage criterion, respectively.Its definition, example and effectiveness are discussed in this paper.
Dynamic processes of photoinduced electron transfer in flavin-porphyrin hetero Langmuir-Blodgett monolayers, which are characterized both by the electronic properties of functional groups and by the structure of molecular organization, have been studied in terms of transient photocurrent properties. From an analysis of transient photocurrent with a kinetic model based on the organic quantum well structure, we can conclude that the photocarrier generation process is mainly due to charge separation from photoexcited flavin to porphyrin at the flavin-porphyrin molecular heterojunction, and that the charge shift in monolayers and charge transfer between monolayers and an electrode are controlled by applied electric field.
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