- Volume 73, Issue 1, 1972
Volume 73, Issue 1, 1972
- Article
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Pneumococcal Transformation – A Backward View Fourth Griffith Memorial Lecture
More LessProfessor C. M. MacLeod, President of the Oklahoma Medical Research Foundation, Oklahoma, U.S.A., who had agreed to give the 1972 Griffith Memorial Lecture, died on 12 February, 1972. No text of his lecture was available. Professor A. W. Downie generously agreed, at short notice, to give the lecture which follows, and which uses Professor MacLeod’s intended title.
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- Biochemistry
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Carbon Dioxide Fixation by Verticillium albo-atrum
More LessSUMMARY: Verticillium albo-atrum required CO2 for growth when glucose or glycerol was the sole carbon source but not when succinate or acetate was supplied. The yeast form of the fungus fixed 14C from NaH14O3 into extracellular metabolites (I to 2 %), low-molecular-weight intracellular components (17 %), lipids (3 %), nucleic acids (34 %) and proteins (42 %). The only radioactive protein components were aspartate (33%), glutamate (33%), arginine+lysine (22%), and leucine + isoleucine (6 %). Nucleic acid bases that contained appreciable 14C were uracil (27 %), cytosine (21 %), adenine (22 %), guanine (27 %) and thymine (4 %). Carbon dioxide fixation appeared to be important for the anaplerotic biosynthesis of four-carbon intermediates and for purine biosynthesis.
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Binding of Benzimidazole Compounds to Conidia of Pithomyces chartarum
More LessSUMMARY: Conidia of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis strain c rapidly bound benzimidazole (BIZ), thiabendazole (TBZ), furidazole (FUD), and 2-phenyl benzimidazole (PBIZ) when mixed with aqueous solutions of the compounds at room temperature. Almost complete removal (> 95%) of the compounds from solution could be achieved by raising the spore/compound ratio in the reaction mixtures. The binding process was temperature-independent over the range of o to 65°C and pH-dependent (optimum at pH 4.5). BIZ binding was more sensitive to variation of ionic strength than was binding of TBZ, FUD or PBIZ.
Binding of BIZ conformed to the Langmuir adsorption isotherm; binding of the substituted benzimidazoles conformed to the isotherm over only part of the concentration range tested. Analysis of the binding data indicated that BIZ was bound to a single class of sites on the spore surface while the substituted benzimidazoles were bound to two or more classes differing in their affinity. This adsorption may be the first in a series of events leading to inhibition of spore germination by benzimidazole derivatives.
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- Development And Structure
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Conidiophore and Spore Development in Aspergillus nidulans
More LessSUMMARY: Conidiophore development was studied in wild-type and structurally defective mutants of Aspergillus nidulans. Cytoplasmic vesicles were found concentrated at growing apices. Plasmalemmasomes occurred frequently in the subapical and basal cytoplasm of growing sterigmata and near their developing septa; after septum formation they were flattened against the septa and the wall of the older cell and were associated with lomasomes. At this stage the wall developed a superficial lamina; the basipetally budding spore chain was invested from its initiation by a continuation of this lamina. The lamina was also associated with a dense network in the medium around the basal mycelium. The inner, secondary wall of the conidiophore became more electron-lucent with age; the continuity between this wall and the single wall of the sterigmata suggested this structure to be the site of action of the bristle locus. Pigmentation of wild-type and mutant conidiophores was associated with an electron-dense modification of the outer, primary wall. Stratification of the spore wall was indicated only by the similar development of a layer of electron-dense material. Cytoplasmic microfilaments were observed in all parts of the colony.
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- Ecology
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Acidophilic Thiobacilli in the River Sirppujoki
More LessSUMMARY: Numbers of acidophilic thiosulphate-oxidizing and iron-oxidizing thiobacilli in the River Sirppujoki (S.W. Finland) were monitored through one annual cycle. A number of physical and chemical environmental variables of the river water were determined (temperature, discharge, pH values, titratable acidity, and concentrations of manganese, iron and sulphate). Thiobacilli in river water appeared mainly to have been washed in from the soil. Once in the river a slow loss of viability occurred, strongly influenced by the temperature. The methods for quantitative colony counts of acidophilic thiobacilli were deemed unsatisfactory.
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- Genetics And Molecular Biology
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Isolation and Characterization of Mutants Resistant against Chlorate of Bacillus licheniformis
More LessSUMMARY: From Bacillus licheniformis s244, 45 chl deletion mutants have been isolated which belong to six groups. In four groups the identity of the auxotrophic markers deleted has been established: his-2, ura-I, arg-3 and trp-I. Furthermore, a leu and a glu marker were found in the two other groups of deletion mutants. From B. licheniformis S1026, derived from strain ATCC9945A, 36 single site mutants were obtained and classified into eight groups, chl A to H, by transformation and phage SP 15-mediated transduction. The glu deletion comprises the mutations chl A and B. In total, 13 chl mutations have been found and there may be up to 13 chl genes. Of the single-site chl mutations, only chl E is linked with a known reference marker, ura-I. All chl mutants are unable to form nitrate reductase under conditions of oxygen shortage. This nitrate reductase is mainly associated with the cytoplasmic membrane. Most mutations have pleiotropic effects: (i) retarded growth under anaerobic conditions; (ii) an increased sensitivity to penicillin and related antibiotics; (iii) completely altered membrane protein patterns on acrylamide-SDS gels.
In the wild-types, II membrane protein bands are observed. There are only small, quantitative differences between membrane protein patterns of cells cultivated aerobically or anaerobically. Membrane protein patterns of the chl mutants are most different from those of the wild-types after anaerobic cultivation. Differences include appearance of a new protein band, disappearances, decreases, doublings and often large increases of other protein bands. Aerobically, the mutants have membrane protein patterns less different from those of the wild-types. Differences include appearance of a new protein band, decrease and disappearance of protein bands. An explanation for all these changes may be a wholesale disorganization of protoplasmic membrane biosynthesis.
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Polytransductant Formation in Escherichia coli Lysogens
More LessSUMMARY: When a strain of Escherichia coli lysogenic for λ and deleted for the gal operon was infected with λdg two types of gal+ transductants arose, an expected class with enzyme levels similar to wild-type, and a exceptional class with elevated levels of enzyme and altered staining reactions on indicator plates. Transductants of the exceptional class appear to carry multiple copies of a homoimmune λdg prophage. When exceptional transductants were prepared carrying a ts kinase mutation in their λdg and then selected for ability to grow at high temperatures, two types of λdg could subsequently be isolated from the temperature-resistant revertants, one carrying a temperature-resistant and the other a temperature-sensitive kinase gene. It has been possible to infer the existence of polytransductants containing more than two transducing prophage by their segregation patterns. The rate at which such cells produce phage, after u.v. induction, in a medium with galactose as the sole carbon source, is accounted for by the polytransductant structure.
Polytransductant cells arose following infection by λdg at very low multiplicities. Identification of prophage types after mixed infection with genetically marked λdg's showed that each polytransductant carried only one type of transducing phage. When the superinfecting transducing phage was unable to make active λ repressor, as is the case for λpg8 -C1857 at high temperature, the frequency of polytransductant formation was enhanced. Inhibition of protein synthesis with chloramphenicol also enhanced polytransductant formation. These experiments suggest that, at least in the case of λdg, limited phage replication does take place in immune hosts, and is followed by multiple integrations into the bacterial chromosome.
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Methionine Transport in Wild-type and Transport-defective Mutants of Salmonella typhimurium
More LessSUMMARY: Salmonella typhimurium possesses a permease specific for L-methionine (Km of 0.1 to 0.2 µM). Competition studies have shown that the permease has little or no affinity for the other L-amino acids commonly found in proteins. Methionine uptake was competitively inhibited by the growth inhibitory analogues DL-ethionine, α-methyl-DL-methionine and DL-methionine-DL-sulphoximine. Mutants resistant to α-methyl-methionine and methionine sulphoximine have been isolated which were severely defective in the methionine specific permease. Two of these mutants, metP760 and metP761, mapped away from all previously located methionine structural and regulatory genes.
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Tryptophan Transport in Neurospora crassa by Various Types of mtr Revertants
More LessSUMMARY: Reversions in a strain of Neurospora crassa carrying the mtr-26 allele may result from at least two types of mutations: (i) intralocus mutations which may or may not occur at the primary mutational site; (ii) unlinked suppressor mutations which may or may not be allele specific. The uptake of 14C-labelled tryptophan in mtr+ , mtr and mtr (revertant) strains has been studied. Revertant strains have been isolated in which the rate of tryptophan transport is one half of that in mtr- cells. These revertants include those resulting from intragenic suppression of the mtr phenotype as well as those resulting from mutation at unlinked suppressor loci. Possible explanations for this reduced rate of transport are discussed. This paper also reports the occurrence of an unlinked allele specific suppressor in Neurospora which may suppress a frameshift mutation.
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Selective Evolution of Phenylacetamide-utilizing Strains of Pseudomonas aeruginosa
More LessSUMMARY: Mutants of Pseudomonas aeruginosa PACI were isolated which, unlike the wild-type, could utilize phenylacetamide as a nitrogen source for growth. One group of these mutants had lost the ability to grow on acetamide; the second group grew slowly on acetamide. Group I included 12 mutants isolated from the magno-constitutive butyramide-utilizing strain PAC351 and one mutant isolated from the valeramide-utilizing mutant PAC360. Group I Ph amidases hydrolysed phenylacetamide, butyramide and valeramide but not acetamide or formamide. Group II Ph mutants produced thermolabile amidases which attacked the same range of amide substrates but in addition had weak activity towards acetamide. Three group II mutants were derived from a constitutive butyramide-regulator mutant PAC128; one from PAC360 and one from PAC326, a mutant producing a defective amidase.
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Evidence for Mutation to Streptomycin Resistance in Clinical Strains of Staphylococcus aureus
R. W. Lacey and I. ChopraSUMMARY: In three clinical strains of Staphylococcus aureus and one laboratory mutant (609 str-r) the gene determining streptomycin resistance was probably at a single chromosomal locus. Cell-free systems from these, and an additional clinical strain, showed little inhibition of protein synthesis in the presence of streptomycin, whereas systems from sensitive staphylococci were markedly affected by streptomycin.
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- Physiology And Growth
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Release of Protoplasts from Schizophyllum commune by a Lytic Enzyme Preparation from Trichoderma viride
More LessSUMMARY: Spherical, osmotically sensitive protoplasts were liberated from the mycelium of Schizophyllum commune through the action of an extracellular enzyme preparation from the culture filtrate of Trichoderma viride grown on hyphal walls of the former organism. The conditions for obtaining stable protoplasts were determined. Maximum numbers of protoplasts were released from young growing mycelium by using MgSO4 or KCI at an osmotic potential between −12.8 and −17.8 atm in the presence of 0.05 M-maleic acid-NaOH at pH 5.8. Protoplasts were released through ruptures in the wall, initially at the apices, but later also from older parts of the hyphae.
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Continuous Culture Studies on the Biosynthesis of Alkaline Protease, Neutral Protease and α-Amylase by Bacillus subtilis NRRL-B3411
More LessSUMMARY: The amounts of three catabolite repressible enzymes, alkaline protease, neutral protease and α-amylase, produced by Bacillus subtilis NRRL-B3411 growing in a chemostat, depended on the growth-limiting substrate. Limiting growth with glucose was advantageous for α-amylase synthesis while nitrogen-limited growth was advantageous for synthesis of the two proteases. Under the conditions used, continuous cultures were unsuitable for large-scale production of the three enzymes since spontaneous mutations to less productive strains occurred in the long term.
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Metabolism of Threonine by Penicillia: Growth on Threonine as the Sole Carbon and Nitrogen Source
More LessSUMMARY: Two species of Penicillium were isolated from soil by their ability to grow aerobically on L-threonine as sole source of energy and cellular carbon and nitrogen. Threonine-grown fungi contained a highly active inducible L-threonine: NAD+ dehydrogenase and a significantly less active constitutive ‘biosynthetic’ threonine dehydratase, but possessed no L-threonine: acetaldehyde lyase activity. The 2-amino-3-oxobutyrate formed by initial dehydrogenation of threonine was subsequently cleaved in both fungi to acetyl-CoA and glycine in a coenzyme-A-dependent cleavage catalysed by a 2-amino-3-oxobutyrate: CoA ligase which was inducibly synthesized during growth on threonine and not during growth on acetate plus glycine.
During growth of both fungi on threonine, 14C from L-[U-14C]threonine was rapidly incorporated into glycine and malate, and thereafter into citrate, aspartate, glutamate, succinate and various other metabolites. The time-dependent distribution of 14C among metabolites in these short-term incubations with L-[U-14C] threonine showed that acetyl-CoA produced by the NAD+ plus coenzyme-A-dependent cleavage of threonine was metabolized via the tricarboxylic acid cycle plus glyoxylate cycle.
Comparative enzyme induction patterns after growth of both fungi on a wide range of carbon sources showed that glycine produced by the NAD+ plus coenzyme-A-dependent cleavage of threonine was metabolized via the glycerate pathway.
There was no evidence from either comparative enzyme induction patterns or incorporation of 14C from L-[U-14C]threonine of aminoacetone production and further metabolism by both fungi, even though a small amount of this amino-ketone appeared in culture media during growth on threonine.
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Metabolic Activity of Purified Suspensions of Mycobacterium lepraemurium
More LessSUMMARY: Metabolism of Mycobacterium lepraemurium harvested from infected mice was studied using radioisotope tracer techniques. 14C-labelled acetate, fumarate, glycerol, α-ketoglutarate, glutamine and succinate were oxidized and assimilated, but at extremely low rates. Asparagine and glucose were assimilated but not oxidized. These data provide unequivocal evidence for the utilization of exogenous substrates by purified suspensions of M. lepraemurium and indicate the existence of a host-independent aerobic metabolism and an operative tricarboxylic acid cycle.
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- Short Communications
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- Taxonomy
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A Co-operative Numerical Analysis of Rapidly Growing Mycobacteria
SUMMARY: A co-operative numerical taxonomic analysis of rapidly growing mycobacteria of Runyon’s group IV is reported. There was no limitation on the number, nature, or method of performance of the test characters contributed by each of the 12 participants. Initially 415 test characters were coded for analysis; deletion of irrelevant and repetitious data resulted in a final 195 characters used to generate the matching matrix. All nine major clusters defined in the study were of named species; however, three of these were noted to contain two or more species and the reduction of some of these to synonymy with prior epithets is discussed. Recognized clusters were: Mycobacterium smegmatis, M. phlei, M. vaccae (including M. para-fortuitum), M. diernhoferi, M. flavescens, the rhodochrous taxon, M. thamnopheos, M. fortuitum, M. chelonei. Results of the pooled information are compared with those of the individual participants. Immunological results generally correlated well with numerical analyses.
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