摘要:

Morphological and physiological characteristics of seven strains of yeast-like symbionts isolated fromSitodrepa paniceajustify their, inclusion into the genusTorulopsisas a new species:T.buchnerii. The symbiotic relationship is mutually beneficial: the symbionts obtain some nitrogenous compounds and carbohydrates, such as proline and trehalose from the host's hemolymph, and synthesize and make available to the host all the essential amino acids and vitamins, except biotin.

ISSN:0008-4166    

DOI:10.1139/m76-210

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Pseudomonas aeruginosa(ATCC 9027) releases four periplasm-located enzymes, i.e., ribonuclease (EC 3.1.4.22; EC 3.1.4.23), alkaline phosphatase (EC 3.1.3.1), cyclic-2′, 3′-phosphodiesterase (EC 3.1.4.d), and 5′-nucleotidase (EC 3.1.3.5) into the medium during growth. Ribonuclease and alkaline phosphatase are classed as enzymes which are readily extracted by osmotic shock and spheroplast formation whereas cyclic-2′,3′-phosphodiesterase and 5′-nucleotidase are classed as enzymes which are not readily extracted by these procedures. In view of the relative ease of extraction of the former enzymes it is suggested that the latter enzymes, cyclic-2′,3′-phosphodiesterase and 5′-nucleotidase, are bound and located in the periplasm in a manner different to ribonuclease and alkaline phosphatase.

ISSN:0008-4166    

DOI:10.1139/m76-211

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Observations made in our laboratory during the past 3 years showed that the growth of someNeisseria gonorrhoeaecultures was inhibited in the presence of various bacterial contaminants of urogenital specimens. A total of 647 cultures confirmed as containingN.gonorrhoeaewere examined in this study. The first part of the study was carried out on 520N.gonorrhoeaecultures. Of these 520 cultures, 110 (21.1%) showed contamination on purity plates (GC medium, antibiotic-free). When further subcultured, 96 (87.3%) of theN.gonorrhoeaestrains grew in pure culture, but 14 (12.7%) failed to grow. Subsequently, experiments were carried out on 127 pureN.gonorrhoeaecultures. The bacterial species that inhibited the growth ofN.gonorrhoeaeare listed in order of frequency:Neisseria meningitidis,Staphylococcus epidermidis,Corynehacteriumspecies,Staphylococcus aureus,Streptococcusgroup A, andNeisseria subflava.

ISSN:0008-4166    

DOI:10.1139/m76-212

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Deoxyribonuclease (DNase) activity was found in the culture fluids of numerous marine bacteria isolated from seawater. Among these organisms, marine bacterium,Vibriosp., strain No. 2, showed the highest deoxyribonucleic acid – hydrolyzing activity. This organism requires salts of seawater for both growth and extracellular DNase formation. The DNase activity could not be detected in the synthetic seawater culture liquid lacking magnesium ion, and DNase activity decreased in a calcium-deficient medium. The optimum temperature for the growth of this organism was between 15 and 25 °C. The formation of extracellular DNase was the greatest at 20 °C and less activity was found at 10 and 30 °C.

ISSN:0008-4166    

DOI:10.1139/m76-213

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Extracellular nuclease produced by a marineVibriosp., strain No. 2, was purified by salting out with ammonium sulfate and by chromatography on a DEAE-cellulose column and twice on a Sephadex G-200 column. The nuclease was eluted as a single peak in which the deoxyribonuclease (DNase) activity and ribonuclease (RNase) activity appeared together. Polyacrylamide disc gel electrophoresis showed a single band of stained protein which had both DNase and RNase activity. The molecular weight of the enzyme was estimated to be 100 000 daltons. When using partially purified enzyme from the DEAE-cellulose column, the optimum pH for activity was 8.0, and the enzyme was activated strongly by 0.05 MMg2+ion and stabilized by 0.01 MCa2+ion. These concentrations of Mg2+and Ca2+ions are similar to those of the two cations in seawater. Indeed, the enzyme revealed high activity and strong stability when kept in seawater. The presence of particulate matter, such as cellulose powder, chitin powder, Hyflosupercel, Kaolin, and marine mud increased the stability of the enzyme. When the hydrostatic pressure was increased from 1 to 1000 atmospheres, the decrements of the enzyme activity were more pronounced at 30 and 40 °C than at 25 or 50 °C. The enzyme activity was restored after decompression to 1 atm at 30 °C.

ISSN:0008-4166    

DOI:10.1139/m76-214

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The role of macrophages on the course of an infection withToxoplasma gondiihas been examined. Stimulation of macrophage function by killedBordetella pertussiscells did not show any beneficial effect as an increased susceptibility became apparent. The functional blockade of macrophages by dextran sulfate or carbon particles did not result in a higher susceptibility of mice to the lethal primary infection withT.gondii. Thus in vivo macrophages apparently do not play an essential role as effector cells as they do in infections with other obligate intracellular infective organisms such asListeria monocytogenes.The spleen is apparently of crucial importance for resistance againstT.gondiiinfection, since death occured earlier in splenectomized mice than in control animals.

ISSN:0008-4166    

DOI:10.1139/m76-215

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A comparison of the ability of vesicular stomatitis virus (VSV) to generate and replicate defective interfering (DI) particles in primary chick embryo (CE) and mouse L cells was investigated as a means of analyzing host control over DI-particle synthesis and interfering capacity. Serial undiluted passage of VSV in CE and L cells indicate that VSV-DI particles are generated and (or) replicate with greater efficiency in CE than in L cells. When DI particles accumulate in L cells, they are able to interfere with infectious particle replication. The DI particles from CE cells interfered to the same extent with infectious particle replication in both CE and L cells. L cells, therefore, are not considered 'low-interference' hosts in which DI particles are produced and do not interfere with infectious virus replication, but rather hosts which restrict the production of DI particles.

ISSN:0008-4166    

DOI:10.1139/m76-216

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A survey in various countries revealed that the N2-fixingSpirillum lipoferumBeijerinck is a very common root and soil inhabitant in the tropics. More than half of the grass root and soil samples collected in tropical countries (four African countries and Brazil) contained abundantS.lipoferumpopulations, while less than 10% of the samples collected in temperate South Brazil, Kenya, and the U.S.A. contained the organism. There is a pronounced vegetation effect.Panicum maximumseems the most favorable among the forage grasses, while few positive samples were found under virgin tropical forest. Legume roots contained lessS.lipoferumthan adjacent soils. More than 80% of the samples from cereal roots (maize, sorghum, wheat, and rye) grown in fields fertilized with PK and Mo, in Rio de Janeiro State, were positive. Maize and sorghum grown under similar conditions in Wisconsin contained less than 10% of positive samples, but when maize fields were inoculated 90% of the root samples containedS.lipoferum. Alluvial soils were more favorable than eroded hill soils. Occurrence in soil was strongly pH-dependent with a pH around 7, being optimal (correlation coefficientr = 0.90). Sporadic occurrence was observed even in soils with pH 4.8. Surface-sterilizedP.maximumroots collected from soils with pH ranging from 4.8 to 7.2 contained highS.lipoferumnumbers which did not correlate with soil pH(r = 0.41). Amendment with malate of acid soils was not very effective in increasing nitrogenase (N2-ase) activity, but in two soils with pH above 6.4, high N2-ase activity was obtained after 16 to 48 h of incubation. In two soils from a temperate climate region, inoculation withS.lipoferumincreased N2-ase activity produced through malate amendment.

ISSN:0008-4166    

DOI:10.1139/m76-217

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Attempts have been made to keep in vitro, for extended periods of time, cultures of chick embryo fibroblasts transformed by the Schmidt–Ruppin strain of Rous sarcoma virus, subgroup D. Roller cultures of transformed chick cells kept in serum-deficient medium can be maintained without subcultivation for up to 6 months. The confluent cultures continuously release viruses and viable tumor cells into the medium. The released cells can be plated and have characteristics of growth and morphology which are relatively stable with time until the culture degenerates. Cells released at later stages of the culture produced substantially more viruses than those released earlier, suggesting that cell selection or differentiation occurs during long-term cultivation in low serum concentration. Long-term cultures of untransformed chick embryo fibroblasts can also be maintained in the same way. The release of viable cells by these confluent cultures, however, is negligible.

ISSN:0008-4166    

DOI:10.1139/m76-218

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Orange-red-pigmented (OR) colonies were isolated from cream-yellow-pigmentedMycobacterium smegmatisafter exposure to either mycobacteriophage MC4 or ultraviolet light; these variant strains were designated OR4 and ORuv, respectively. Early subculture of OR-colonies did not show any segregation of parental-type cells. However, colonies resembling the parental strains, possibly representing a back mutant (REV-OR4), were occasionally found during subculture of established OR-colonies or upon treatment withN-nitroso-N′-nitro-N-methylguanidine. The OR-variants were characterized by their lytic response to nocardiophage, but not to mycobacteriophages, presence of α-branched, β-hydroxylated fatty acids of theNocardia-type, and a guanine plus cytosine value of deoxyribonucleic acid (DNA) between 62 and 64 mol %. They were more resistant to the lethal action of both ultraviolet light and mitomycin C treatment than the parental and back mutant strains.Although the OR-variants in this study possess characteristics common to the genusNocardiaor some of the 'rhodochrous' mycobacteria, evidence is presented that they form a new class of mycobacterial variants.

ISSN:0008-4166    

DOI:10.1139/m76-219

出版商:NRC Research Press    

年代:1976

数据来源: NRC