ISOLATION AND PROPERTIES OF TEMPERATURE-SENSITIVE MUTANTS OF GROUP II RNA PHAGE GA

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Twenty-one temperature-sensitive (ts) mutants were isolated from group II RNA phage GA after nitrous acid mutagenesis. They formed plaques at 32°C, but not at 40°C. The eclipse period, latent period, and burst size of GA were 18 minutes, 25 minutes, and 800 at 37°C, respectively.Cell cultures infected with moi of 5 of these ts mutants were incubated for 40 minutes, first at 40°C and then at 32°C. Release of progenies began 1 minute after the temperature-shift for ts, 20, but was delayed by 14 to 28 minutes for ts 4 and ts 25. From the results of temperature-shift experiments, the 21 ts mutants were classified into 3 groups; that is, early (E), middle (M), and late (L) function mutants. The E mutants (6 ts mutants with ts 25) were thought to have been blocked in the early stage of infection. The M mutants (5 ts mutants with ts 4) and L mutants (10 ts mutants with ts 20) were presumed to have been middle and late function mutants, respectively.The ts mutants were examined for ability to produce serum-blocking power (SBP) at a nonpermissive temperature (41°C). The L mutants produced much SBP (about 50% of GA) at 41°C, but the E mutants produced no detectable amounts of SBP. The SBP of the M mutants was less than 11 phage particles per induced cell.The grouping of the ts mutants based on physiological properties was in good accordance with the results of the complementation test. These results suggest that the E mutant may probably be a replicate one and the M mutant a coat protein one, and that the L mutant may have a defect in the A protein cistron. Asymmetric complementation was observed for the first time in group II RNA phage GA. In the cross between ts 4 (M mutant) and ts 11 (L mutant), about 79% of the total progenies produced were ts 4.
日本ウイルス学会の論文

ISOLATION AND PROPERTIES OF TEMPERATURE-SENSITIVE MUTANTS OF GROUP II RNA PHAGE GA

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日本ウイルス学会 | 論文

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