摘要:

An alternative method for nutrient dosing in continuous phased culture is described. In this procedure the volumes of gas and culture remain unchanged in the system. This facilitates transfers of medium and effluent culture in the culture vessel and permits experimental manipulations additional to those obtained with the previously described method of dilution phasing. The two methods of dilution and displacement dosing are compared.

ISSN:0008-4166    

DOI:10.1139/m71-073

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Hyphae ofVerticillium dahliaeKleb. penetrated the roots of tomato and pea seedlings and induced the deposition of lignitubers between the host plasmalemma and cell wall. Lignitubers prevented further colonization by the fungus which underwent protoplasmic lysis within the lignituber. Evidence is also presented to suggest that lignituber formation results from the extrusion of vesicles by the host.

ISSN:0008-4166    

DOI:10.1139/m71-074

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Cells ofMycobacterium vaccaestrain JOB5 grown on ethane, propane, orn-butane contained about twice as much lipid as cells grown on acetate, isopropanol, or propionate. Propane-grown cells contained more neutral lipid (34.4%) than acetate-grown cells (19.4%) and there was a correspondingly greater percentage of phospholipid in acetate-grown cells. When cells grown on acetate were harvested and resuspended in a growth medium with propane as substrate, the synthesis of lipid preceded synthesis of nitrogenous components and cell multiplication. The lipid fraction that increased most by growth on propane was triglyceride. It is suggested that this lipid may play a role in the assimilation of the hydrophobic hydrocarbon substrate.

ISSN:0008-4166    

DOI:10.1139/m71-075

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The effect of urea on the stability and the state of aggregation of glutamine synthetase is reported. Substrates and modulators of this enzyme exert a protective effect against urea-induced loss of activity. On partial inactivation by urea, the enzyme appears to consist of a dimeric species and an intermediate, partially unfolded form. Subsequent to the removal of urea, the presence of substrates and effectors is necessary to bring about a reversal of inactivation and a return of the enzyme lo the native or near-native state.

ISSN:0008-4166    

DOI:10.1139/m71-076

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Infection ofEscherichia coliby R23 results in a marked inhibition of rRNA synthesis. Both 16 S and 23 S RNA are inhibited with maximal inhibition occurring at 30 min. Inhibition of 4 S RNA is not as profound. DNA synthesis is also inhibited after R23 infection although infected cells continue to divide for about one generation (45–60 min) after infection.

ISSN:0008-4166    

DOI:10.1139/m71-077

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Neonatal rabbits were injected with large amounts of pooled normal A/Jax strain mouse liver and serum to induce tolerance to the organ and species antigens present in this mixture. At 3 months of age, the "tolerant" and uninjected control rabbits were all challenged with either A/Jax strain heart and (or) liver or kidney and their responses were compared by precipitation, hemagglutination (HA), and indirect fluorescent antibody tests (IFab). The normal sera showed one to four precipitation arcs on two-dimensional immunodiffusion analysis against their respective organ antigens and those demonstrable on immunoelectrophoresis migrated predominantly in the β and γ globulin regions. Organ-specific antibodies reacting with the organ antigens of the immunizing species and heterologous species were easily quantified by HA titrations and localized by IFab tests. It was noted that antigens common to the tissues of the immunizing species were found principally in the supportive cell structures whereas organ-specific antigens were found in the cytoplasmic region of the immunizing tissue and in similar tissues of different species.Antisera derived from the "tolerant" rabbits immunized with heart and (or) liver showed virtually normal heart specific responses while the response to liver was significantly suppressed. The complete absence of the cross reaction to guinea pig liver in the "tolerant" sera was taken as evidence of the tolerance mediated suppression of the reactivity to some of the mouse liver antigenic determinants.

ISSN:0008-4166    

DOI:10.1139/m71-078

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A sensitive electron microscopic method has been developed to determine the antigenic relationship within the picornavirus group. Negatively stained mixtures of antigens (poliovirus type 1 and 3, echovirus type 9, and coxsackievirus type A9) and antibodies (poliovirus type 3 and echovirus type 9 antisera) were examined under the electron microscope. The results showed clumping of homologous and heterologous viruses with both antisera, which was considered as evidence of cross-reaction. The controls showed no clumping or attachment of antibody molecules. The significance of clumping was tested by treating adenovirus type 7 with the two test antisera.

ISSN:0008-4166    

DOI:10.1139/m71-079

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The replication of the SFFV component of a polycythemia-inducing strain of Friend leukemia virus was shown to be enhanced by endotoxin either as purified fraction W ofS.typhosaor present on heat-killedS.typhosaorP.mirabilis. Enhancement occurred to a significant level when the mice were sensitized with either form of endotoxin 5 or 3 days before virus administration. Administration of endotoxin simultaneously with virus resulted in a marked inhibition of SFFV replication. Endotoxin given at times subsequent to viral infection had no effect on SFFV replication. On the other hand the H or flagellar antigen fromP.mirabilisgiven either before, simultaneously with, or after virus infection did not influence the replication of SFFV.

ISSN:0008-4166    

DOI:10.1139/m71-080

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The effects of phenethyl alcohol on DNA synthesis and X-ray-induced DNA excision–repair were studied inMicrococcus radiodurans. At 0.20% concentration, the drug selectively inhibited DNA synthesis. Higher concentrations and prolonged incubation promoted DNA breakdown.Irradiation and PEA together promoted increased DNA breakdown in a characteristic fashion depending upon the time at which it was added. This effect was lost after the cells had undergone one postirradiation division. PEA did not inhibit repair of X-ray-induced single strand breaks. At high doses the two agents no longer enhanced each other's action and this suggests that they acted on a common target. It is proposed that X-ray-induced DNA breakdown is at least partly due to damage of a non-DNA structure such as the cell membrane, since persistent breaks in the DNA are not required for X-ray-induced, PEA-potentiated DNA degradation.

ISSN:0008-4166    

DOI:10.1139/m71-081

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The effect of chloramphenicol (CAP) on the initiation and continuation of DNA repair in X-irradiatedMicrococcus radioduranswas studied. The repair of single strand breaks proceeds by two separate mechanisms, one of which is resistant to CAP, proceeds without thymidine incorporation, and is inhibited by EDTA. This direct repair might be due to the direct action of polynucleotide ligase on breaks with 3′OH and 5′PO4end groups. The other type of repair is the classical repair replication: this requires postirradiation protein synthesis to be initiated but once under way is not halted by CAP.Postirradiation incubation with EDTA irreversibly prevented subsequent direct repair. The hypothesis is advanced that unrepaired breaks were converted to gaps by enzymatic activity during incubation with EDTA.

ISSN:0008-4166    

DOI:10.1139/m71-082

出版商:NRC Research Press    

年代:1971

数据来源: NRC