Parent Culture

2015 ◽  
Keyword(s):  
Parent Culture

The adaptation of Bact. coli mutabile to lactose

1954 ◽  
Vol 223 (1154) ◽  
pp. 420-420
Keyword(s):  
Inoculum Size ◽  
Colony Development ◽  
Lag Phase ◽  
Normal Cells ◽  
Adaptive Process ◽  
Large Numbers ◽  
Parent Culture ◽  
Mutation Theory ◽  
Special Circumstances ◽  
New Evidence

When Bact. coli mutabile not previously exposed to lactose is plated on lactose-ammonium sulphate agar the number of normal-sized colonies (lac + ) eventually formed is a complicated function of the inoculum size. For small numbers all the cells plated eventually form colonies; for large numbers the colony yield is determined not by a number of mutants in the parent culture but by plate exhaustion (for which the earlier developing colonies are chiefly responsible). The time of appearance of the lac + colonies is much longer than with a culture previously grown in lactose. Thus lac + mutants could not have been present from the start unless their growth is inhibited by an excess of normal cells. When, however, a small number of previously adapted cells are mixed with an excess of unadapted cells the presence of the latter does not impede the development on agar of lac + colonies from the former. When cells are first placed in a liquid lactose medium and samples are transferred at intervals during the ensuing lag phase, the time needed for colony development on lactose-agar progressively diminishes, once again showing that an adaptive process is occurring during the lag in the liquid medium. In certain special circumstances the adaptation to the liquid lactose medium may occur with abnormal speed. The growth rate of newly adapted strains is at first variable. If interpreted by a mutation theory the observations would demand the assumption of a complex polygenetic system for which current applications of the Luria-Delbrück and Lea-Coulson theories would be invalid. Recent arguments about the mutational nature of these phenomena are criticized in the light of the new evidence.

scholarly journals On the Nature of Bacterial Lag

1914 ◽  
Vol 14 (2) ◽  
pp. 215-241 ◽  
Author(s):  
William Jas. Penfold
Keyword(s):  
Maximum Rate ◽  
The Other ◽  
Water Culture ◽  
Rate Of Growth ◽  
Heat Stable ◽  
Other Hand ◽  
Parent Culture ◽  
Peptone Water ◽  
Effect On Growth

(1) If B. coli be subcultured into another sample of the same medium when growing at full pace, it will continue to grow at the same pace.(2) If the maximum rate of growth be interrupted by a short application of cold, growth will recommence without lag on the temperature being raised. If the cold be long continued, lag will tend to reappear.(3) Differences in the size of inoculum have practically no effect on lag in the case of large inoculums, in the case of small ones, on the other hand, diminution of the seeding has the effect of lengthening lag, and this lengthening effect is more marked the smaller the seedings become.(4) Lowering the temperature lengthens the lag. The effect is very similar to the effect on growth.(5) The older a parent culture (within limits) the longer the lag.(6) The length of lag varies with the medium even if adaptation has been arranged for beforehand.(7) Heat-stable products in B. coli cultures on peptone water have, in the case of overnight cultures, but little effect on lag.(8) After washing the bacteria for two hours with saline in order to remove possible inhibiting agents, it was found that the lag, on subculture, still occurred and was indeed slightly longer.(9) If a peptone water culture of B. coli be centrifuged, it is found that the few bacteria remaining in the supernatant commence to grow again at a quick rate but not without a period of lag.

THE APPLICATION OF SEROLOGICAL METHODS TO THE DIFFERENTIATION OF CLOSELY RELATED SMUT FUNGI

1938 ◽  
Vol 16c (10) ◽  
pp. 391-404 ◽  
Author(s):  
E. C. Beck
Keyword(s):  
Host Plant ◽  
Smut Fungi ◽  
Subsequent Infection ◽  
Parent Culture ◽  
The Family

Serological methods were applied in an attempt to differentiate a number of closely related members of the family Ustilaginaceae. The results of two series of reciprocal precipitin-ring tests showed that different genera and species of the same family were satisfactorily differentiated by this technique; so also were compatible cultures of the same species, where no detectable differences existed, other than the necessity of the haploid counterparts being brought together on the appropriate host plant to induce the diploid phase, and subsequent infection of the host. A parent culture and its mutant that were different morphologically but alike in their pathogenicity, were the only ones that could not be differentiated by this technique. Reciprocal absorption tests were applied to these two fungi, but the powder of either culture absorbed the antibodies of both from the immune sera. Optimal proportions of antigen and antibody were determined, but could not be applied in absorption tests because of the dilution of antisera. Agglutination tests were attempted but were unfruitful.

scholarly journals Appearance of Virulent Bacteriophages in Lysogenic E. coli Cultures after Prolonged Growth in the Presence of Triethylenemelamine

1968 ◽  
Vol 52 (1) ◽  
pp. 136-143 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Continuous Culture ◽  
Ultraviolet Light ◽  
E Coli ◽  
Parent Culture ◽  
Virulent Virus ◽  
Mutant Cells ◽  
Do So

Continuous culture of coli 12λ, P22, 600-434, 600-21, and 600-299 in the presence of triethylenemelamine (TEM) results in the appearance of a new virulent virus which attacks the parent culture. N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) is effective with 600-21 and ultraviolet light with 12λ and 600-21. The cultures which produce the virulent virus continue to do so indefinitely in the absence of the mutagen, but are not lysogenic for the virus. Most of the cells in such cultures are resistant to the virus and do not produce any, but there are a few mutant cells sensitive to the virus and the virus multiplies by infection of these sensitive mutants.

STUDIES ON PLAQUE VARIANTS OF COXSACKIEVIRUS B5 BY BURST ANALYSES

1967 ◽  
Vol 13 (2) ◽  
pp. 167-172
Author(s):  
Jack Konowalchuk ◽  
Joan I. Speirs
Keyword(s):  
Cell Lines ◽  
Large Population ◽  
Small Population ◽  
Monkey Kidney ◽  
Large Plaque ◽  
Parent Culture ◽  
Normal Monkey ◽  
Small Pool ◽  
Selection For ◽  
Section Analysis

Propagation of coxsackievirus B5 on cell lines revealed two variants, one that yields small plaques and is stable and another that is large but variable in size. Multiple-burst studies on the large-plaque pool showed the existence of two different population sections. Analysis of a sample from a plaque belonging to the small population section showed a progeny of small plaques while a similar analysis from a plaque in the large population section produced plaques of varying size but whose mean plaque diameter resembled that of the parent culture. Repeated selection for smallness from plaques in the large population section resulted in small plaques and a shift from the large to the small population section. Analysis of the small pool virus on monkey kidney monolayers revealed the presence of a few typical monkey kidney plaques which differed from normal monkey kidney plaques by producing only small plaques on HEp-2 monolayers.

Africanism

1971 ◽  
Vol 1 ◽  
pp. 12-14
Author(s):  
Mazi E. N. Njaka
Keyword(s):  
Cultural Setting ◽  
Sufficient Knowledge ◽  
Parent Culture ◽  
Salutary Effect ◽  
Modes Of Thought

To write about a culture and its relevance of thought using techniques and methodology invented in another culture can be deceptive. Every culture has its raison d’etre. The ideology of a society moulds its culture as well as the values of that society. Those members of a society who have been indoctrinated and miseducated in another cultural setting simply do not qualify to use the techniques they have learned in formulating a framework for the constructs and principles of the culture in which they were born. They do not have sufficient knowledge of their parent culture, thus their analysis can be misleading and full of disturbed facts and findings. However, they can attempt to rediscover their culture and ascertain the salutary effect that certain of its characteristics or modes of thought might have when applied or adapted to another culture.

SURVIVAL OF SINGLE-BASIDIOSPORE ISOLATES OF RHIZOCTONIA PRATICOLA AND RHIZOCTONIA SOLANI

1964 ◽  
Vol 10 (5) ◽  
pp. 739-746 ◽  
Author(s):  
George C. Papavizas
Keyword(s):  
Organic Matter ◽  
Rhizoctonia Solani ◽  
High Tolerance ◽  
Single Spore ◽  
Time Rate ◽  
Unamended Soil ◽  
Parent Culture ◽  
Oat Straw ◽  
Rhizoctonia Praticola ◽  
Rate Of Decline

Twenty randomly selected single-basidiospore isolates from each of Rhizoctonia praticola and R. solani differed considerably in their tolerance to CO2, competitive saprophytic activity, and ability to survive within precolonized substrate segments incubated in soils with or without pentachloronitrobenzene (PCNB) or oat straw. With a few exceptions, isolates possessing high saprophytic activity also possessed high tolerance to CO2 and high surviving ability in precolonized substrate. Several single-spore isolates of R. solani possessed higher ability for saprophytic survival in organic matter and lower CO2-sensitivity than their parent culture. Survival of single-basidiospore isolates in precolonized substrate segments was greater in unamended soil or soil amended with oat straw than in soil treated with PCNB. Mature oat straw reduced surviving ability of several isolates, whereas it increased surviving ability of others above that observed in unamended soil. The isolates whose surviving ability was increased by oat straw were mostly those possessing high saprophytic activity in unamended soil. Saprophytic activity and virulence of all isolates tested declined with time. Rate of decline of virulence was much more rapid for weak than strong saprophytes.

Production of aflatoxin by Aspergillus wentii Wehmer

1969 ◽  
Vol 15 (8) ◽  
pp. 895-898 ◽  
Author(s):  
H. W. Schroeder ◽  
M. Jacqueline Verrett
Keyword(s):  
Chick Embryo ◽  
Aflatoxin Production ◽  
Single Spore ◽  
Two Cultures ◽  
Additional Requirement ◽  
Field Corn ◽  
Parent Culture ◽  
Aspergillus Wentii ◽  
Aflatoxin B

Two cultures of Aspergillus wentii isolated from white field corn were tested through three consecutive single-spore generations for the ability to produce aflatoxins. Aflatoxin production by A. wentii was established. Production was low and variable. The variability was apparently not due to inhomogeneity in the parent culture. The identity of aflatoxin B1 was confirmed by chemical derivative tests and by the chick embryo bioassay. The ability to accumulate, as well as to produce, the aflatoxins is suggested as an additional requirement to qualify a fungus as an aflatoxin producer.

scholarly journals Identification of Dehalobacter reductive dehalogenases that catalyse dechlorination of chloroform, 1,1,1-trichloroethane and 1,1-dichloroethane

2013 ◽  
Vol 368 (1616) ◽  
pp. 20120318 ◽  
Author(s):  
Shuiquan Tang ◽  
Elizabeth A. Edwards
Keyword(s):  
Amino Acid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Amino Acid Identity ◽  
Reference Database ◽  
Binding Motifs ◽  
Acid Identity ◽  
Parent Culture ◽  
Liquid Chromatography Tandem Mass ◽  
Native Polyacrylamide Gel Electrophoresis ◽  
Associated Proteins

Two novel reductive dehalogenases (RDases) that are highly similar to each other but catalyse distinct dechlorination reactions were identified from Dehalobacter -containing mixed cultures. These two RDases were partially purified from crude protein extracts of anaerobic dechlorinating enrichment cultures using blue native polyacrylamide gel electrophoresis. Gel slices were assayed for dechlorinating activity, and associated proteins were identified using liquid chromatography tandem mass spectrometry with the metagenome of the parent culture as the reference database. The two RDases identified, annotated as CfrA and DcrA, share an amino acid identity of 95.2 per cent, but use different substrates: CfrA dechlorinates chloroform (CF) and 1,1,1-trichloroethane (1,1,1-TCA), but not 1,1-dichloroethane; DcrA dechlorinates 1,1-dichloroethane, but not CF or 1,1,1-TCA. These two novel RDases share no more than 40 per cent amino acid identity to any other known or putative RDases, but both have a twin-arginine motif and two iron–sulfur binding motifs conserved in most RDases. Peptides specific to two putative membrane anchor proteins, annotated as CfrB and DcrB, were also detected in gel slices.

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