摘要:

Cell extracts ofPseudomonasC12B synthesized choline sulfate (COS) from SO42−, choline chloride, and ATP. However, most of the COS-forming activity was found in culture medium supernatants of this bacterium, and that which remained with the cells was cell wall-associated. Enzyme release was independent of the carbon and (or) sulfur source used for growth and was not suppressed by increasing the divalent cation concentration of the medium. The COS-synthesizing system was inhibited in vitro byL-cysteine, SO42−(> 0.1 mM), and choline chloride (> 0.1 M).L-Cysteine (0.1–5.0 mM) did not repress the synthesis of enzymes present in the system. COS formation from SO42−in vitro was increased 2.8-fold by 10 mMadenosine 5′-phosphosulfate (APS) and 5-fold by 1 mM3′-phosphoadenosine-5′-phosphosulfate (PAPS) during a 4-h incubation period. APS (10 mM) also inhibited the incorporation of35SO42−into COS. Culture supernatants incubated with Na235SO4produced two35S-labelled metabolites having electrophoretic mobilities similar to those exhibited by authentic APS and PAPS. The synthesis of these metabolites was also inhibited in vitro by unlabelled APS and byL-cysteine.

ISSN:0008-4166    

DOI:10.1139/m77-072

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The enzyme succinate dehydrogenase (SDH, succinate: (acceptor) oxidoreductase, EC 1.3.99.1) was localized by the combined techniques of cytochemistry and electron microscopy in the hyphae of a self-parasitizing isolate ofSaprolegnia megaspermaCoker. The enzyme was localized in the mitochondrial membranes; its activity was inhibited by malonate. Electron-dense deposits, whose formation was not prevented by the addition of malonate, appeared outside of the hyphal cell walls. No evidence was found at the ultrastructural level within the vegetative hyphae for any abnormalities which could be linked to the phenomenon of self-parasitism.

ISSN:0008-4166    

DOI:10.1139/m77-073

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Sequential changes induced by an equine adenovirus in cultured fetal equine kidney cells were studied by electron microscopy. The first morphological change was the appearance of type I inclusions. These inclusions developed to type II inclusions which appeared as ring forms. Type III inclusions were formed within the central part of type II inclusions and finally filled up most of the nuclear space. As the infection proceeded, type IV inclusions which appeared as dense dark-staining spheres were formed at the center of the type III inclusions and also inside the cytoplasm. These dark-staining spheres developed and their center was filled with light-staining material and virus particles which eventually resulted in the formation of type V inclusions. Autoradiography study showed that types I, II, and III were composed of nucleoprotein and type IV was composed of protein.

ISSN:0008-4166    

DOI:10.1139/m77-074

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

C-phycocyanin from two strains of the thermotolerant blue-green alga,Mastigocladus laminosus(NZ-DB2-m and I-30-m), that grow within different temperature ranges have been characterized with respect to aggregation, immunologic properties, subunit composition, and thermodenaturation. The critical thermal-denaturation temperature for phycocyanin from both strains ofM.laminosusphycocyanin is 60 °C which is higher than that for mesophilic phycocyanin. Immunodiffusion studies have shown that these two strains ofM.laminosusexhibit no antigenic differences and are closely related to the mesophilicPlectonema calothricoidesand the thermophilicSynechococcus lividus(strain 3). Neither phenol nor α-naphthol has any effect on phycocyanin aggregation in these two strains ofM.laminosus. There is also no enhancement of formation of large aggregates at their elevated temperature of cultivation. Furthermore, the phycocyanin of both strains ofM.laminosusdoes not demonstrate any large amount of 19S or higher aggregates at any pH value. These observations suggest that the mode of adaptation ofM.laminosusphycocyanin to high temperature is different from that previously encountered. It is also important to note that phycocyanin is essentially unchanged whether it is extracted from the same strain,M.laminosus(NZ-DB2-m), grown at either 50° or 37 °C.

ISSN:0008-4166    

DOI:10.1139/m77-075

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The induction of microcyst formation could be triggered in washed amoebae of the cellular slime moldPolysphondylium pallidum(strain-2) by the addition of 2 mMethionine. Methionine at a ratio of 2:1 with ethionine would inhibit microcyst induction by ethionine. The involvement of polyamines in morphogenesis was also shown. Putrescine (0.02 to 0.1 M) induced the formation of microcysts, whereas spermidine (2 to 4 mM) was capable of causing a fourfold reduction in 0.05 Mputrescine-induced microcysts but incapable of inhibiting microcyst induction by 0.08 Mputrescine. Glycerol (0.5 Mor 0.4 M) was also found to be an effective inducer of microcysts.

ISSN:0008-4166    

DOI:10.1139/m77-076

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Levels of neutralizing antibody to lymphocytic choriomeningitis (LCM) virus in the sera of 66 infected persons were assayed by a rapid fluorescent focus-inhibition test (RFFIT). The test was more sensitive than the mouse-neutralization (MN) test and could be completed in less than 24 h. The RFFIT titers were compared with titers obtained by the indirect fluorescent-antibody (IFA) and complement-fixation (CF) tests. Neutralizing antibody detected by the RFFIT remained positive after IFA, CF, and MN antibodies had disappeared. The RFFIT for detection of LCM antibody is specific and reproducible and seems especially useful for determining the incidence and epidemiology of LCM virus infections.

ISSN:0008-4166    

DOI:10.1139/m77-077

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The ability of crude, semi-purified, and purified rubella antigens to elicit a specific and significant blast cell transformation of lymphocytes from immune individuals was investigated in 25 seronegative and 25 seropositive young adults.The type of preparation and the purity of the antigens were critical. Titration of the antigens by complement fixation or hemagglutination was of little value for selecting the best antigen which was a whole virion-purified antigen.

ISSN:0008-4166    

DOI:10.1139/m77-078

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Three, two major and one minor, distinct RNA polymerases have been isolated and partially purified from heterotrophically grownRhodospirillum rubrum, a facultative photosynthetic bacterium. Associated with each of these three enzymes is a distinct polyadenylic acid polyemrase. All of these enzyme activities are dependent on DNA templates and are resistant to rifampicin and streptovaricin. The structural subunit composition, the response to various chemical compounds and DNA templates, and the properties of the products of these enzymes are studied in detail and compared with those of similar enzyme activities from other bacterial systems. Several unique features have been observed in theR.rubrumenzyme systems, such as an uneven incorporation of purine and pyrimidine nucleotides by the RNA polymerases, and the presence of a lag period in the polyadenylic acid polymerase activities.

ISSN:0008-4166    

DOI:10.1139/m77-079

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Trypticase soy broth was superior to nutrient and lactose broths as a preenrichment medium for the detection ofSalmonellain artificially and naturally contaminated gelatin. The detection rates forSalmonellawere further enhanced when homogenization of the gelatine–broth mixture was accomplished by the use of gelatinase rather than by heating to 45 °C. Detection rates were also increased by adjusting the pH of the gelatine–broth mixture to 7.0, the optimum pH for gelatinase (EC 3.4.23.2) activity.

ISSN:0008-4166    

DOI:10.1139/m77-080

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A previously described procedure for the selective enrichment ofShigellain competition withE.colihas been modified and tested with a total of 48 strains of the fourShigellaspecies. The new enrichment medium consists of 1.5-strength trypticase soy broth, 1 mM4-chloro-2-cyclopentylphenyl β-D-galactopyranoside (CPPG), 0.25% lactose, and 0.1 Mcitrate buffer (pH 6.2). In competition with a 1000-fold higher population ofE.colithanShigella, 42 of 48 strains from the four species ofShigellawere selectively enriched by the new method. Different lots of CPPG did not appear to affect the performance of the medium.

ISSN:0008-4166    

DOI:10.1139/m77-081

出版商:NRC Research Press    

年代:1977

数据来源: NRC