- Volume 68, Issue 2, 1971
Volume 68, Issue 2, 1971
- Biochemistry
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The Incorporation of Elaidate, Oleate and Straight-chain Saturated Fatty Acids by Mycoplasma Strain Y
More LessSUMMARY: Mycoplasma strain y grew well in a partly defined medium containing charcoal- treated bovine serum albumin (BSA) with added elaidate, elaidate plus oleate, or elaidate plus a saturated fatty acid containing 10 to 15, 22 or 24 carbon atoms. With elaidate plus a saturated acid containing 16 to 20 carbon atoms there was good growth after a variable lag period. When elaidate was the only fatty acid supplied it comprised from 93 to 95 % of the total fatty acids in stationary-phase myco- plasmas, the remainder being derived from contaminating fatty acids in the medium. There was no isomerization of elaidate to oleate. When grown with elaidate plus a shorter-chain saturated acid (C10, C12) or with a long-chain acid (C22, C24), elaidate was incorporated preferentially during the early stages of growth, increasing proportions of the saturated acids being incorporated during the later stages. When grown with elaidate plus a saturated acid of intermediate chain length (C14 to C16), or with elaidate plus oleate, both fatty acids were incorporated in approximately equal proportions throughout growth. The preferential incorporation of elaidate in the early growth stages with some pairs of fatty acids is explained by a competition between the two fatty acids for the BSA binding sites.
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The Effect of Straight-chain Saturated, Monoenoic and Branched-chain Fatty Acids on Growth and Fatty Acid Composition of Mycoplasma Strain Y
More LessSummary: The fatty acid growth requirements of a sterol-requiring Mycoplasma (strain y), unable to synthesize or alter the chain length of either saturated or unsaturated fatty acids, were investigated. In some cases adaptation was required for growth when mycoplasmas were transferred to media of differing fatty acid composition. No straight-chain saturated acid supported growth when tested alone, but good growth was obtained with three branched-chain acids (isopalmitate, isostearate and anteisoheptadecanoate) tested singly and with some straight-chain saturated acids when tested in pairs (e.g. when equal proportions of C12 and C22 acids were supplied together).
Of the unsaturated fatty acids tested, cis-12-octadecenoate and two trans-octadecenoates (elaidate and trans-vaccenate) supported good growth alone. Little or no growth was obtained with any cis-monoenoic acid of the oleic acid series unless a straight-chain acid was also supplied and both the chain length of the monoenoic acid and the position of the double bond had a marked effect on the range of saturated acids with which it could be successfully paired. With myrist-oleate, long-chain saturated acids of chain length C20, C22 gave the best growth; with oleate the range extended from C12 to C20 (optimal at C17) and with erucate from C10 to C18 (optimal at C15). When the double bond was near the carboxyl group, as in cis-6-octadecenoate, strain y grew only when paired with C14 to C16 saturated acids; as it became further removed from the carboxyl group as in cis-vaccenate, addition of a single saturated acid from an extended range (C10 to C24) could support growth.
Only those fatty acids supplied in the growth medium were present in the lipids of the organism, and in cases where strain y grew well when a single fatty acid was supplied, this was the sole fatty acid found. Marked differences in morphology were observed in mycoplasmas of differing fatty acid composition.
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- Development And Structure
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Fine Structure of Spore Germination in Botrytis cinerea
More LessSUMMARYThe ultrastructure of germinating Botrytis cinerea conidia was studied using three different fixatives. Good fixation and embedment of dormant spores was achieved. The wall of the dormant spore was composed of two layers. During germination three new wall layers were formed between the original wall and the cytoplasm; the inner two layers were continuous around the spore cytoplasm whilst the third was formed only near the point of germ-tube emergence and was continuous with the germ-tube wall. The conidial wall increased in thickness from 263 to 339 nm. during germination. It was calculated that, as a result of spore swelling alone, the dormant spore wall would decrease in thickness from 263 to 178 nm. An apical corpuscle was observed in the germ-tube wall during germination.
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- Genetics And Molecular Biology
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The Linkage Map of Streptomyces rimosus
More LessSUMMARY: Haploid recombinant selection has been used to map the loci of 24 auxotrophic mutations on a circular linkage group in an industrial strain of Streptomyces rimosus. The features of crosses are similar to those in S. coelicolor a 3 (2), except for the recovery of variable numbers of heterokaryons on selective media in S. rimosus crosses. By a suitable choice of selected marker combinations, heterokaryons can be largely eliminated. The linkage map of S. rimosus is extremely similar to that of S. coelicolor a 3 (2); this may indicate a conservation of gene arrangement in prokaryotes as already suggested by the similarity of linkage relationships in Escherichia coli and Salmonella typhimurium. The S. rimosus map provides further support for the idea of circular symmetry of the Streptomyces linkage map first proposed for S. coelicolor a 3 (2).
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Pre- and Post-irradiation Effects upon Lethality and Reversion in Salmonella typhimurium
More LessSUMMARYLag, exponential and stationary phase cells of Salmonella typhimurium lt-2 (trpC3) grown in nutrient broth or tryptophan-supplemented minimal medium were irradiated with doses of u.v. up to 570 ergs/mm2. Casein hydrolysate supplementation of the post-irradiation plating medium causes enhanced survival only for lag and exponential phase broth-grown and exponential phase minimal- grown cells. Caffeine invariably leads to decreased survival levels and abolition of any casein hydrolysate enhancement of survival. Cells of all six growth conditions give induced Trp+ reversions, often due to suppressor mutations, on plating media containing casein hydrolysate. Only for minimal-grown lag and exponential phase cells do any induced Trp+ appear on media devoid of casein hydrolysate supplementation. In these cases too, caffeine has a definite antimutagenic action. Mutation frequency decline (MFD) experiments revealed that those cells exhibiting a casein hydrolysate enhancement of survival on plates also show a delayed onset of MFD and a fall of survival, after an initial delay, in liquid minimal medium. MFD experiments in liquid do not give a complete quantitative explanation for the Trp+ revertant yields found on plates. We suggest that intracellular free amino acid pool sizes may be a common factor in the correlations which we have observed.
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- Physiology And Growth
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Inhibition of Growth and RNA Biosynthesis of Bacillus cereus by Quinacrine
More LessSUMMARYThe addition of 0·4 mm-quinacrine to exponential cultures of Bacillus cereus led to the complete inhibition of growth, measured turbidimetrically. Certain metal ions such as Ca2+ and Mg2+ were partially effective in preventing growth inhibition, as was the polyamine spermine.
Quinacrine inhibited most biosynthetic processes measured to the same extent as the reduction in the rate of growth. Thus the incorporation of amino acids into protein, that of diaminopimelic acid into bacterial wall, the accumulation of K+ and the uptake of nicotinic acid were diminished only in accordance with the decreased rate of turbidimetric increase. DNA biosynthesis was decreased to a lesser extent than was turbidity and continued even after growth had ceased altogether, thus indicating less inhibition of this process than that of protein formation. RNA synthesis, on the other hand, was selectively inhibited in these cells. The depressant effect was most pronounced when ribosomal or rRNA formation was examined. RNA isolated from drug-treated cells still exhibited messenger function. An additional effect of quinacrine on the uptake of certain nucleic acid bases is also postulated. The relative content of ATP in the cells was considerably increased by drug treatment.
It appears that quinacrine did not exert its major action on DNA biosynthesis but selectively blocked RNA formation while that of DNA was permitted to continue.
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- Short Communications
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- Taxonomy
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Mycobacterium obuense, a Rapidly Growing Scotochromogenic Mycobacterium Capable of Forming a Black Product from p-Aminosalicylate and Salicylate
More LessSUMMARYFive strains of rapidly growing scotochromogenic mycobacteria were shown to have a capacity to degrade p-aminosalicylate and salicylate, forming a black product(s). The organisms dilfer distinctly from known mycobacterial species that have this capacity, Mycobacterium fortuitum, M. abscessus and M. borstelense, and from other mycobacteria. The organisms are considered to belong to a new species of the genus Mycobacterium and are named Mycobacterium obuense sp. nov.
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Electrophorethic Analysis of Esterases and Other Soluble Proteins from Representatives of Phytopathogenic Bacterial Genera
More LessSUMMARY: Electrophoretic patterns of esterases and other soluble proteins from two isolates of Agrobacterium rhizogenes, three of A. tumefaciens, two of Corynebacterium faciens, eight of C. michiganense, three of Pseudomonas phaseolicola, two of Erwinia carotovora, and four of Xanthomonas fragariae were determined. Similar protein patterns were obtained for isolates representing a given bacterial species, with the exception of one isolate of A. tumefaciens which differed markedly from the other two isolates tested. All isolates possessed active esterases. None of the Corynebacterium isolates tested showed activity bands for dehydrogenases. Results demonstrated the applicability of the technique in differentiating between phytobacterial genera and between species of a given genus.
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Differentiation among Xanthomonas Species by Polyacrylamide Gel Electrophoresis of Soluble Proteins
More LessSummary: Electrophoretic patterns of esterases, phosphatases, of malate, glucose-6-phosphate and α-glycerophosphate dehydrogenases, and of other soluble proteins of 69 isolates representing 21 species of Xanthomonas were determined. Electrophoretic protein patterns were generally identical for all isolates of the same species but dissimilar for different species. Most species showed multiple forms of enzymes. The pattern of α-glycerophosphate dehydrogenase was identical in all species and may be genus-specific. Esterases and phosphatases varied widely among species. In most cases, however, taxon-specific patterns, with slight quantitative variations, were evident. No lactate dehydrogenase activity was detected. This technique appears useful in differentiating among Xanthomonas species which until now have been identifiable only by their specific pathogenicity.
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Comparison of Four Methods for Demonstrating Glucose Breakdown by Bacteria
More LessSUMMARY: Four methods for demonstrating the breakdown of glucose by bacteria have been compared, three of which depended on showing the production of acid from glucose and the fourth on detecting the removal of glucose from the medium. The four methods varied in sensitivity with different groups of bacteria and possible reasons for this are discussed in terms of interaction between glucose and protein metabolism.
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- Corrigendum
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Volumes and issues
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Volume 170 (2024)
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