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O Grau

Publications and source records attributed to O Grau.

44 records · Page 3Linked to original sources
PubMed1981

DNA gyrase inhibitors block development of Bacillus subtilis bacteriophage SP01.

SP01 development was inhibited by nalidixic acid and novobiocin in the sensitive host Bacillus subtilis 168M. Inhibition by novobiocin was prevented by a Novr mutation in the cellular DNA gyrase gene. Nalidixic acid inhibition persisted in hosts carrying a Nalr gyrase, but could be overcome by phage mutation. We conclude that SP01 requires for its development subunit B of the host DNA gyrase, but replaces or modifies subunit A.

Bacillus subtilis↗
PubMed1980

Novobiocin blocks the shutoff of SPO1 early transcription.

Novobiocin, an inhibitor of bacterial DNA gyrase strongly impairs the development of bacteriophage SPOl. DNA replication seems to be the primary target for the antibiotic in this system, but viral-coded transcription is also affected in several aspects: (a) The level of phage transcription is diminished; (b) the shutoff of the synthesis of early RNA classes is inhibited; (c) RNAs of late class are not synthesized. This last effect is a consequence of the coupling between transcription and replication. The other two results could be taken as an indication that the appropriate secondary structure of the parental phage DNA is a requisite for the recognition of promoters. The introduction of negative turns by DNA gyrase seems to make early genes unavailable for transcription.

Bacillus subtilis↗
PubMed1978

Bacteriophage SPO1 development: defects in a gene 31 mutant.

SPO1 temperature-sensitive mutant ts14-1, located in cistron 31, has a DD (DNA synthesis-delayed) phenotype at 37 degrees C and produces progeny in a stretched program. At 44 degrees C it behaves as a DO (DNA synthesis-defective) mutant and shuts off the viral RNA synthesis about 10 min after infection. The thermal sensitivity of this mutant is due to the inactivity of gp-31 (the product of gene 31) at 44 degrees C. However, gp-31 is synthesized at that temperature and partly recovers its activity at 37 degrees C. Only 5 min at the permissive temperature is enough to trigger the continuation of the phage program and to produce progeny. The partial defect at 37 degrees C and the expansion of the middle program together with the pleiotropic defects at the nonpermissive temperature could be suitable for the study of the controls involved in bacteriophage development.

Bacillus subtilis↗
PubMed1976

RNA composition of Junin virus.

Junin virus grown in BHK-21 cells was labeled with [3H]uridine and highly purified by differential and isopycnic centrifugation. The RNAs extracted with phenol and analyzed by polyacrylamide gel electrophoresis were shown to be composed of four large species (33, 28, and 18S) and three small ones (4, 5, and 5.5S). This pattern was similar to ones already reported for other arenaviruses. However, there was a striking difference when the virus labeling was performed in the presence of actinomycin D. Labeling of viral rRNA was as much as 60% of the levels obtained in the absence of the drug under conditions in which cellular rRNA's were inhibited by 95% or more.

Arboviruses↗
PubMed1970

Transcriptions of the bacteriophage T4 template in vitro: separation of "delayed early" from "immediate early" transcription.

The synthesis of different early T4 transcripts by E. coli RNA polymerase in vitro can be dissociated in two ways: (1) when T4 DNA is mechanically degraded, it selectively loses the ability to serve as a template for the transcription of delayed early T4 RNA; (2) when initiation of RNA synthesis on intact T4 DNA is limited to a very short time interval immediate early T4 RNA is synthesized at once but delayed early polynucleotide sequences appear only after a time lag. We conclude that initiation sites for T4 early RNA synthesis are closer to immediate early than to delayed early segments of the T4 template and that immediate early and delayed early segments of the T4 chromosome are interspersed. We propose that this interspersing is significant for the programming of transcription during T4 development.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Citrus psorosis is probably caused by a bipartite ssRNA virus.

Isolate 90-1-1 Concordia (Argentina) of the citrus psorosis agent was graft-transmitted to citrus and mechanically transmitted to Chenopodium quinoa, which was used as a local lesion assay host. Infected citrus and C. quinoa plant lesions were used as starting materials for the purification of the psorosis-associated agent. In extracts partially purified by differential centrifugation, infectivity was abolished by RNase treatment, even in 0.3 M NaCl, indicating that ssRNA is required for biological activity. The total loss of infectivity produced by proteinase K treatment and the decline in infectivity caused by phenol extraction indicated that protein may be essential for infectivity. When partially purified extracts were subjected to sucrose density gradient centrifugation, infectivity on C. quinoa from certain 2-fraction combinations was higher than expected, compared to the infectivity of the individual fractions. Therefore, infectivity was not associated with a single component but with the combination of at least two components which were distinguishable on sedimentation. The infectious material was present in the top and bottom zones of a sucrose gradient, which on further purification by a second gradient and agarose gel electrophoresis, revealed the presence of a 50-kDa protein. This protein was absent in comparable gradient fractions from healthy plants, and therefore most likely represented the capsid protein of both the top and bottom sucrose gradient zone components. Taken together, these results led to the conclusion that the citrus-psorosis-associated virus (CPsAV) is a multipartite virus, containing ssRNA and a 50-kDa coat protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Argentina↗