摘要:

Planktonic blue-green algae are always associated with bacteria. This association leads to enhanced or abundant algal growth when atmospheric carbon dioxide becomes a limiting factor and bacteria-assimilable carbonaceous matter is added. The study was carried out with 12 bacteria-associated blue-green species and 22 aliphatic, bacteria-assimilable carbon compounds. A normal, phosphate-rich Zehnder–Gorham culture medium (No. 11) was used. The bacterial assimilation of the aliphatic matter apparently leads to the production of CO2, which accelerates algal photosynthesis. The observed growth effects are not specific for a particular algal species. They appear to be specific mainly for the bacteria which happen to be associated with the algal cells. Similar growth enhancement was observed when the atmosphere was enriched with 0.5% CO2. With this augmented supply of atmospheric CO2, however, the enhancing effect of organic matter disappeared. The presence of the organic additives also appears to delay bacterial assimilation of organic chelating agents which have been added to keep iron and essential trace elements accessible to the algae in an alkaline medium. Axenic cultures of those algal species which cannot use added carbonaceous compounds did not show any effect of the additive. The results suggest that bacteria-assimilable carbon compounds may be one of the factors leading to algal bloom in lakes and ponds, especially when growth is not limited by the supply of phosphorus or other inorganic elements.

ISSN:0008-4166    

DOI:10.1139/m71-052

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The levels of several plasma enzymes, plasma virus titers, and the percentages of blood cells which were reticulocytes were determined at intervals following the infection of white Swiss mice with the Friend leukemia virus (FLV). Lactate dehydrogenase, isocitrate dehydrogenase, aldolase, and glutamic-oxalacetic transaminase showed large simultaneous increases, alternating with decreases to normal levels, which coincided with fluctuations in virus titers (spleen focus assay). The time of the initial peaks depended on the inoculum size and was the same within replicate mice but subsequent peaks were not synchronous in different mice. The number of reticulocytes usually showed a similar fluctuation which lagged behind the enzyme and virus titer changes. Simultaneous infection with FLV and the lactate dehydrogenase virus resulted in larger but more erratic plasma enzyme changes. Attempts to associate interferon production with the fluctuating virus titers were unsuccessful.

ISSN:0008-4166    

DOI:10.1139/m71-053

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Quaternary ammonium derivatives of bile acids increase the rate of swelling of washed cells ofPseudomonas aeruginosaincubated in solutions of potassium phosphate and to a lesser extent in solutions of sodium phosphate. The enhanced swelling is proportional to the concentration of the compounds in potassium but not in sodium solutions. The reason for this is that sodium but not potassium can displace the compounds from their attachment to the cell site(s) and the interaction is mixed competitive noncompetitive. Both cations, however, when added to cells before the compounds inhibit their effect. Formaldehyde-treated cells behave essentially in the same way as normal cells, which indicates that the compounds are not inhibiting metabolic pumps but are facilitating diffusion of the ions. As the steroid portion of the molecule becomes less lipophilic by the introduction of hydroxyl groups their activity decreases.

ISSN:0008-4166    

DOI:10.1139/m71-054

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The fungusA.pullulans(=Pullularia pullulans) produces exceptionally large amounts of extracellular sucrase when grown on sucrose monopalmitate, in the presence of Tween 80, and with limited shaking. Under optimum conditions, the culture filtrates contained as much sucrase as commercially available concentrates. The specific activity of theA.pullulansenzyme, after acetone precipitation, was as high as that of commercial preparations.

ISSN:0008-4166    

DOI:10.1139/m71-055

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Numerous microorganisms, antagonistic toward canker fungi,Cytospora cinctaSacc. (Leucostoma cincta(Fr.) v.H.) andC.leucostoma(L.persoonii(Nit) v.H.) were recovered from the outer bark of peach. In unsterilized outer bark, fungi predominated in a population of antagonists that included bacteria and actinomycetes. In surface-sterilized outer bark, antagonistic bacteria predominated. A predominance of antagonists in the spring- and fall-infection periods suggests that they contribute to the control of canker. The important but relatively low proportion of strong antagonists in the microflora of resistant Standard Elberta and Sunhaven varieties may explain in part the prevalence of canker on all varieties of peach. Their absence in favor of weak antagonists on Dixired at this time may contribute to its higher susceptibility (canker counts) than that of Standard Elberta, Sunhaven, and Redhaven varieties.

ISSN:0008-4166    

DOI:10.1139/m71-056

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Cells ofCandida utiliswere grown under carbon limitation in phased culture at a doubling time of 4 h. The phosphorus contents of four (lipid, cold water extractable, RNA, and DNA) fractions, obtained empirically by serial extraction of the cells, were determined at-h intervals during the cell cycle and post-cycle periods. The results showed that the phosphorus composition of the cells was changing throughout both cell cycle and postcycle periods.Each phosphorus fraction doubled during the cell cycle; for the major fractions (cold water extractable P and RNA-P) this occurred as a gradual increase spread over the cell cycle period, but for the minor fractions (lipid-P and DNA-P) the increase was restricted to the latter half of the cell cycle period. Expressed as proportions of the total phosphorus content, the phosphorus contents of the major fractions remained constant, but the minor ones changed during the cell cycle. Other, different, changes were observed between the various fractions during the postcycle period.

ISSN:0008-4166    

DOI:10.1139/m71-057

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A recent investigation has shown that the primary mycelium of aquatic streptomycetes is facultatively aerobic while the secondary mycelium is obligately aerobic. The nature of the differences in aerobic metabolism of various morphological phases in the life history was determined by carbon monoxide inhibition. A slide culture chamber technique which allowed continuous microscopic observation of the growing organism while in various gas environments was used. Two distinct patterns of inhibition were observed. The development of early stages of the life history was inhibited by carbon monoxide in the light and the dark. The site of this inhibition could not be determined. The later stages were inhibited only by carbon monoxide in the dark. This suggested a dependence of the secondary mycelium on the activity of cytochrome oxidase. Thus, the primary and secondary mycelial stages were found to be physiologically distinct.

ISSN:0008-4166    

DOI:10.1139/m71-058

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The total numbers of yeasts, bacteria, and coliforms found at five stations in the St. Lawrence River, sampled during a 5-month period in the summer of 1968, were compared to temperature, depth, biological oxygen demand (BOD), dissolved oxygen (DO), and salinity. Averaged data indicate some relationships exist among the biological and physical parameters but examination of the data for the individual samples do not lead to the same conclusions. However, the large increase in numbers ofRhodotorula glutinis(the dominant species of the 'pink yeasts') was found to follow the decrease in bacterial numbers, both total count and coliforms, after the introduction of sewage pollution. The metabolic characteristics of these 'pink yeasts,' allowing them to show such rapid increases in numbers, are not known.

ISSN:0008-4166    

DOI:10.1139/m71-059

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Ultrastructural studies upon the development of coxsackievirus B-3 lesion in the olfactory bulb of the hibernating, experimentally infected adult squirrel (Citellus lateralis) revealed two or possibly three types of pathological reactions. (1) Changes, which occurred before virus replication in the brain, resembled an acute allergic reaction with extensive hemorrhages and neutrophil infiltration, fibrinoid deposits, thrombus formation, and lytic tissue breakdown in the neuropil. (2) Pathological changes resulting primarily from virus replication which succeeded the allergic reaction. (3) A reaction which coincided with and followed the virus replication and was associated with an influx of antibody-producing cells into the olfactory bulb and might prove to be the result of a delayed hypersensitivity.

ISSN:0008-4166    

DOI:10.1139/m71-060

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Study by light microscopy of induced wall-defective variants ofStreptococcus faecaliswas undertaken to examine the sequential development of these forms during a 36-day period. Particularly noted were the early cell wall deficient forms observed at 36 h which appear as "cartwheels." Evolution of these forms through the various stages of the granular-appearing colonies to the classical "fried egg" morphology is described. A similar developmental pattern was observed with both a prototype of the test organism as well as with a fresh isolate from the genitourinary tract of a patient.Colonies of induced wall-defective variants ofS.faecalisgrown on an induction medium were examined in the electron microscope by use of the technique of ultrathin sectioning. This study was undertaken to examine, at the cellular level, the colonial morphology of these variants and to describe differences existing in specified areas of the colony. Longitudinal thin sections of the induced wall-defective colonies were prepared from three levels of the colonies as they related to the medium surface: supraagar surface; subagar surface; and deep subagar. Examination of the thin sections offers evidence that the bacterial population in a single colony is morphologically heterogeneous.

ISSN:0008-4166    

DOI:10.1139/m71-061

出版商:NRC Research Press    

年代:1971

数据来源: NRC