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efficient modulation of glucolipid enzyme activities in membranes of acholeplasma laidlawii by the type of lipids in the bilayer matrix.it is generally anticipated, but so far not fully shown, that the physical properties of membrane lipid bilayers are governed by the concerted actions of the lipid-synthesizing enzymes. in the membrane of acholeplasma laidlawii a constant surface charge density, similar phase equilibria, and a nearly constant spontaneous curvature are maintained for the polar lipids. important for these properties are monoglucosyldiacylglycerol (mglcdag) and diglucosyldiacylglycerol (dglcdag), forming mainly rev ...19957577924
quantitation of the phase preferences of the major lipids of the acholeplasma laidlawii b membrane.we have quantitated the phase preferences of all of the quantitatively significant lipids of fatty acid-homogeneous acholeplasma laidlawii membranes by determining the effect of small amounts of each lipid on the lamellar/reversed hexagonal phase transition temperature of a phosphatidylethanolamine matrix of identical fatty acid composition using differential scanning calorimetry. we find that the incorporation of small amounts of these lipids produce effects ranging from a moderate depression t ...19957577974
acholeplasma laidlawii b membranes contain a lipid (glycerylphosphoryldiglucosyldiacylglycerol) which forms micelles rather than lamellar or reversed phases when dispersed in water.it has been proposed that each of the lipids from the acholeplasma laidlawii membrane prefers to form either a lamellar or a reversed cubic or hexagonal phase when dispersed in excess water at physiologically relevant temperatures and ionic strengths. in this study, we have reinvestigated the thermotropic phase behavior of all the major membrane lipids from a. laidlawii b membranes derived from cells grown in equimolar palmitic and elaidic acids. we confirm that phosphatidylglycerol (pg) and dig ...19957577975
lipid extracts from membranes of acholeplasma laidlawii a grown with different fatty acids have a nearly constant spontaneous curvature.x-ray diffraction methods were used to explore the variation in the spontaneous curvature of lipid extracts from acholeplasma laidlawii strain a-ef22 grown with different mixtures of palmitic acid and oleic acid. it was shown that the cells respond to the different growing conditions by altering the polar head group compositions in order to keep the phase transition between lamellar and nonlamellar structures within a narrow temperature range. this has been interpreted to mean that the membrane ...19957599176
structures of glucolipids from the membrane of acholeplasma laidlawii strain a-ef22. iii. monoglucosyldiacylglycerol, diglucosyldiacylglycerol, and monoacyldiglucosyldiacylglycerol.the structures of three glucolipids from the membrane of acholeplasma laidlawii, strain a-ef22, were determined by high resolution 1h-nmr and 13c-nmr spectroscopy. the two most abundant glucolipids in this organism were shown to be 1,2-diacyl-3-o-(alpha-d-glucopyranosyl)-sn-glycerol (mglcdag) and 1,2-diacyl-3-o-[alpha-d-glucopyranosyl-(1 --> 2)-o-alpha-d- glucopyranosyl]-sn-glycerol (dglcdag). these structures agree with those determined previously by chemical analyses of the two most abundant g ...19957654774
[the phenotypic traits of mollicutes as their possible phylogenetic markers].interaction of cells of mollicutes acholeplasma laidlawii pg 8, a. laidlawii var. granulum 18, mycoplasma hominis pg 21, m. pneumoniae fh, m. fermentans pg 118 and their extracellular products with different carbohydrates, plant lectins of different carbohydrate specificity with glycocalix carbohydrates of the same microorganisms has been studied. basing on this study and data from literature a conclusion is made that such phenotypical characteristics as the ability to form extracellular fructos ...19957655655
[the ability of the oligodeoxyribonucleotides complementary to the 3'-terminal segment of 16s-rrna in mollicutes to suppress translation in their ribosomes in an in-vitro system].effect of oligodesoxyribonucleotide, complementary to 3'-end sequence (3'-ucuuuccuccac) of 16s-rrna of mollicutes, and its phenasine derivatives on the process of translation of mollicute has been studied in the system of in vitro translation, created on the basis of ribosomes of acholeplasma laidlawii var. granulum str. 118 and germ extracts of the wheat and optimized in respect of the temperature (23 degrees c), translation time (70 min), concentration of potassium and magnesium ions (150 and ...19957655656
possible monosaccharide composition of glycopolymers located on the external side of membranes of cells of some mollicutes.monosaccharide composition of glycopolymers of five mollicutes (mycoplasma pneumoniae fh, m. hominis pg 21, m. fermentans pg 18, acholeplasma laidlawii pg 8 and a. laidlawii var. granulum 118) integrated with their membrane has been studied by means of nine plant lectins with certain carbohydrate specificity labelled with colloid gold. monosaccharide composition of glycopolymers depends both on the mollicute species and on its capacity to evoke diseases in different microorganisms. thus genetica ...19957663744
phylogenetic analysis of mycoplasma strain ism1499 and its assignment to the acholeplasma oculi strain cluster.a mycoplasma strain designated ism1499 was used to develop a mycoplasma genetic system (g. g. mahairas and f. c. minion, j. bacteriol. 171:1775-1780, 1989; g. g. mahairas, c. jian, and f. c. minion, gene 93:61-65, 1990), but phenotypic inconsistencies led to the conclusion that this organism had been classified incorrectly as a member of the species mycoplasma pulmonis. studies were initiated to determine the proper taxonomic position of ism1499, and on the basis of the results of our genetic an ...19957857790
membrane lipid composition and cell size of acholeplasma laidlawii strain a are strongly influenced by lipid acyl chain length.the small, cell-wall-less prokaryote acholeplasma laidlawii strain a-ef22 could grow with membrane lipids having an average acyl chain length cn varying over 14.5- almost 20 carbons by exogenous supplementation with selected fatty acids. for 16 < cn < 18, the cells grew with lipids containing 100% (mol/100 mol) monounsaturated acyl chains, whereas for cn < 16 and cn > 18, cell growth only occurred with gradually lower fractions of unsaturated chains. cn was actively increased and decreased by ch ...19957867633
structures of glucolipids from the membrane of acholeplasma laidlawii strain a-ef22. i. glycerophosphoryldiglucosyldiacylglycerol and monoacylbisglycerophosphoryldiglucosyldiacylglycerol.the structures of two phosphoglucolipids from the membrane of acholeplasma laidlawii, strain a-ef22 were determined by high resolution 13c-, 31p- and 1h-nmr. the lipids in question are 1,2-diacyl-3-o-[glycerophosphoryl-6-o-(alpha-d-glucopyranosyl- (1-->2)-o-alpha-d-glucopyranosyl)]-sn-glycerol (1) and 1,2-diacyl-3-o-[glycerophosphoryl-6-o-(alpha-d-glucopyranosyl-(1-- >2)- monoacyl-glycerophosphoryl-6-o-alpha-d-glucopyranosyl)]-sn-glycero l (2). both lipids are thus derivatives of diglucosyldiacy ...19947918591
membrane thickness and molecular ordering in acholeplasma laidlawii strain a studied by 2h nmr spectroscopy.since acholeplasma laidlawii can be restricted to incorporating fatty acids from the growth medium into its membrane lipids, it is possible to study the effects of the length of the acyl chains on the properties of the membrane of the organism. a. laidlawii strain a-ef22 was grown with mixtures of one perdeuterated saturated fatty acid and one monounsaturated fatty acid. the average length (<cn>) of the acyl chains in the membrane lipids varied from 14.6 to 19.9, and the degree of unsaturation r ...19947947725
tubular structures of mycoplasma gallisepticum and their possible participation in cell motility.in five strains of mycoplasma gallisepticum, a protein with a molecular mass of about 40 kda was detected by immunoblotting with anti-pig brain tubulin polyclonal and monoclonal antibodies. in eight other mycoplasma species similarly tested no reaction was observed. thin serial sections of m. gallisepticum and acholeplasma laidlawii cells examined by transmission electron microscopy revealed a submembrane system of tubules in m. gallisepticum but not in a. laidlawii. the intracellular spatial di ...19948012588
[the effect of mycoplasmal contamination of cultures of skin fibroblasts from the indian muntjac and of the subsequent decontamination of the cultures using ciprofloxacin on the karyotypic structure of the cell line].the karyotypic variability of indian muntjac skin fibroblast cell line, cultured for 95-168 days after contamination with acholeplasma laidlawii strain pg-8, has been investigated. the contaminated cultures differ from noncontaminated ones in cell distribution for chromosome number. the noncontaminated cultures have modal number of chromosomes equal to 7 with the main structure variant of the karyotype (svk) 2+2+1+1+1. in the contaminated cultures the cell number with 7 chromosomes and the main ...19947809977
structures of glucolipids from the membrane of acholeplasma laidlawii strain a-ef22. ii. monoacylmonoglucosyldiacylglycerol.the structure of one glucolipid from the membrane of acholeplasma laidlawii, strain a-ef22, was determined. this glucolipid is synthesized only when a large fraction of saturated, straight-chain fatty acids are incorporated into the membrane lipids of strain a-ef22. the lipid was studied by 1h- and 13c-nmr spectroscopy. the structure of the lipid is 1,2-diacyl-3-o-[6-o-acyl-(alpha-d-glucopyranosyl)]-sn-glycerol. the result for this lipid shows that a previously published structure, based on inco ...19947811721
thermotropic phase properties of 1,2-di-o-tetradecyl-3-o-(3-o-methyl- beta-d-glucopyranosyl)-sn-glycerol.the hydration properties and the phase structure of 1,2-di-o-tetradecyl-3-o(3-o-methyl-beta-d-glucopyranosyl)-sn-glycerol (3-o-me-beta-d-glcdaig) in water have been studied via differential scanning calorimetry, 1h-nmr and 2h-nmr spectroscopy, and x-ray diffraction. results indicate that this lipid forms a crystalline (lc) phase up to temperatures of 60-70 degrees c, where a transition through a metastable reversed hexagonal (hll) phase to a reversed micellar solution (l2) phase occurs. experime ...19947811919
mycoplasma stimulates hiv-1 expression from acutely- and dormantly-infected promonocyte/monoblastoid cell lines.treatment of a myelo-monocyte cell line, j22hl-60, dormantly infected with human immunodeficiency virus type 1 (hiv-1) with heat-inactivated extracts of acholeplasma (a) laidlawii (250 micrograms/ml) enhanced virus production more than 45-fold as assessed by p24 viral core antigen assay. when treated with a suboptimal dose of tpa or tnf-alpha, acholeplasma extracts further augmented virus production in j22hl-60 cells. h7, an inhibitor of protein kinase c(pkc), almost completely abrogated hiv-1-i ...19947832648
adaptation to altered growth temperatures in acholeplasma laidlawii b: fourier transform infrared studies of acyl chain conformational order in live cells.acholeplasma laidlawii b cells, highly enriched in saturated c14 and c15 fatty acids, have been grown at several temperatures. conformational order in the acyl chains of live cell membranes has been monitored with fourier-transform infrared (ft-ir) spectroscopy. coupled ch2 wagging progressions, characteristic of the all-trans conformation, have been used to quantitatively monitor the extent of trans-gauche isomerization. a simple model relating the changes in the progression intensity to the in ...19948142410
packing of a triacylglucolipid from the membrane of acholeplasma laidlawii strain a at the air/water interface.pressure-area curves were generated at 22 degrees c and 40 degrees c for three glucolipids isolated from acholeplasma laidlawii strain a-ef22. the glucolipids are 1,2-diacyl-3-o-(alpha-d-glucopyranosyl)-sn-glycerol (mglcdag), 1,2-diacyl-3-o-[alpha-d-glucopyranosyl-(1-->2)-o-alpha-d- glucopyranosyl]-sn-glycerol (dglcdag), and 1,2-diacyl-3-o-[3-o-acyl-(alpha-d-glucopyranosyl)]-sn- glycerol (mamglc-dag). the curves for mglcdag and dglcdag are characteristic for monolayers in a liquid phase at both ...19948142444
rapid, sensitive pcr-based detection of mycoplasmas in simulated samples of animal sera.a fast and simple method to detect mycoplasmal contamination in simulated samples of animal sera by using a pcr was developed. the following five mycoplasma species that are major cell culture contaminants belonging to the class mollicutes were investigated: mycoplasma arginini, acholeplasma laidlawii, mycoplasma hyorhinis, mycoplasma orale, and mycoplasma fermentans. after a concentration step involving seeded sera, genus-specific primers were used to amplify a 717-bp dna fragment within the 16 ...19948161186
novel polar lipid composition of clostridium innocuum as the basis for an assessment of its taxonomic status.the extractable polar lipids of clostridium innocuum have been shown to consist of glycosyldiradylglycerols, phospholipids and phosphoglycolipids. the major glycosyldiradylglycerols are d-glcp(alpha 1-3)radyl2gro and d-galp(alpha 1-2)d-glcp(alpha 1-3)radyl2gro. both glycolipids have some 1-o-(alk-1-enyl)-2-o-acyl species, in addition to diacyl species. the phospholipids include bisphosphatidylglycerol (cardiolipin), lysocardiolipin and phosphatidylglycerol (pg). in addition, several novel lipids ...19948162181
sequence analysis of a unique temperature phage: mycoplasma virus l2.mycoplasma virus l2 is a quasi-spherical enveloped virion containing circular double-stranded dna. l2 infection of acholeplasma laidlawii host cells leads to a noncytocidal productive infection cycle followed by establishment of lysogeny in all (or most) infected cells, with viral dna integrated into the host cell genome. the l2 genome has been sequenced and analyzed. l2 dna is 11,965-bp long and contains 15 open reading frames (orfs). one of these, orf13*, has its start codon within and in the ...19948163159
similar regulatory mechanisms despite differences in membrane lipid composition in acholeplasma laidlawii strains a-ef22 and b-pg9. a multivariate data analysis.mycoplasmas are small, cell wall-deficient bacteria. the metabolic regulation of the lipid composition in the membrane of the species acholeplasma laidlawii, strains a-ef22 and b-ju, is governed mainly by the balance between the potential formation of lamellar and nonlamellar phase structures. however, the regulatory features have not been consistently observed in the b-pg9 strain. a comparison has been performed between the membrane lipid composition for strains a-ef22 and b-pg9, simultaneously ...19948172919
[cloning universal probes for detecting mycoplasma contamination of cell cultures].to obtain the universal polynucleotide hybridization probes for testing mycoplasmal contaminations in cell cultures, we have cloned several dna fragments from the srrna gene of acholeplasma laidlawii. before cloning, in order to exclude cross-hybridization of these probes with eukaryotic rrna, the thermodynamic parameters of duplex formation between dna complementary to mycoplasmal rrna and eukaryotic rrna had been studied. using a set of computer methods, the region which forms weak heteroduple ...19948183277
regulation and phase equilibria of membrane lipids from bacillus megaterium and acholeplasma laidlawii strain a containing methyl-branched acyl chains.phosphatidylethanolamine (pe) was isolated from bacillus megaterium grown at 20 and 55 degrees c (pe-20 and pe-55). iso and anteiso methyl-branched, saturated acyl chains are predominant in b. megaterium, and the value of the molar ratio of iso/anteiso acyl chains is more than 20-fold higher in pe-55 than in pe-20. moreover, about 21 mol% of the acyl chains of pe-20 are monounsaturated. the phase equilibria differ between the two pe preparations: (1) pe-20 is more prone to form reversed nonlamel ...19948193124
phylogenetic classification of phytopathogenic mollicutes by sequence analysis of 16s ribosomal dna.the phylogenetic relationships of 17 phytopathogenic mycoplasmalike organisms (mlos) representing seven major taxonomic groups established on the basis of mlo 16s ribosomal dna (rdna) restriction patterns were examined by performing a sequence analysis of the 16s rdna gene. the sequence data showed that the mlos which we examined are members of a relatively homogeneous group that evolved monophyletically from a common ancestor. in agreement with results obtained previously with other mlos, our r ...19947520735
activation of the membrane glucolipid synthesis in acholeplasma laidlawii by phosphatidylglycerol and other anionic lipids.in membrane lipids of the prokaryote acholeplasma laidlawii similar phase equilibria and a nearly constant spontaneous curvature are maintained by an extensive metabolic regulation of especially the major polar lipids monoglucosyldiacylglycerol (mglcdag) and diglucosyldiacylglycerol (dglcdag), forming nonlamellar and lamellar phases, respectively. a constant surface charge density is maintained by the anionic phospholipid fraction. these lipids are synthesized from phosphatidic acid in two compe ...19948089114
phylogenetic relationships among members of the class mollicutes deduced from rps3 gene sequences.a gene for a ribosomal protein, rps3, was amplified by pcr and sequenced from representatives of the class mollicutes. alignments of the deduced amino acid sequences allowed the construction of a phylogeny that is consistent with the phylogenetic trees created from 5s and 16s rrna comparisons, including the position of the former acholeplasma florum on the mycoplasma branch, rather than with the classical acholeplasmataceae. additional confirmation of the phylogeny comes from the deduction that ...19948123554
systematic development and validation of sanitization protocols for a chromatographic system designed for biotherapeutics purification.production of protein therapeutics through the application of genetic engineering and biotechnology techniques requires comprehensive attention to good manufacturing practice and good laboratory practice (gmp/glp) guidelines for product recovery and purification. validated clean-in-place procedures are part of the master method and require analysis of microbial bioburden to assess the efficacy of cleaning protocols. this article describes the extensive microbial challenge of a chromatography sys ...19938123748
[oligodeoxyribonucleotides complementary to sections of the mollicute ribosomal operon as transcription inhibitors in vitro].antisense oligodeoxyribonucleotides have been studied for their effect on the transcription in vitro in mollicutes. a synthetic fragment of dna [symbol: see text] complementary to that part of dna which codes the 1510-1521 area of the 3'-terminal sequence 16s-prna of all mollicutes was used in the study as well as its modifications by imidasophenasine derivatives: [symbol: see text], [symbol: see text] [symbol: see text]. maximal inhibition of the mollicute transcription in vitro was observed wi ...19937517768
[soluble and semisoluble lectins from mollicutes and their possible functions].when studying mollicute lectins it was established that acholeplasma laidlawii pg-8 synthesizes two half-soluble lectins one of which is specific to n-acetyl-d-glucosamine, and the other--to d-glucosamine.hcl; phytopathogenic strain a. laidlawii var. granulum 118 produced 4 lectins one of which is soluble and specific in respect to fructose-1.6-diphosphate, the rest three lectins are half-soluble and specific to one of the sugars--d-galactosamine.hcl, rafinose and d-glucosamine.hcl. in mycoplasm ...19938220826
[the effect of mycoplasma contamination and decontamination with ciprofloxacin on the karyotypic structure of the chinese hamster v-79 lung cell line].karyotypic variability was investigated for the chinese hamster lung cell line v-79, infected (contaminated) with a mycoplasma acholeplasma laidlawii a. the mycoplasmal contamination did not affect cell distribution for the chromosome number. however, 30-70 days following cell culture contamination the increase in chromosomal aberrations was observed in the contaminated cell line primarily at the expense of chromosomal breaks. the following cyprofloxacin treatment of the culture resulted in myco ...19938266577
an enzyme-linked immunosorbent assay (elisa) for monitoring rodent colonies for streptobacillus moniliformis antibodies.an enzyme-linked immunosorbent assay (elisa) to measure streptobacillus moniliformis antibodies in mice and rats was developed. twelve s. moniliformis strains originating from cases of rat-bite fever and haverhill fever in man and from various rodent species, showed considerable serological relationship. the elisa appeared specific since antibodies to s. moniliformis were absorbed by autologous and homologous antigen, but not by heterologous bacterial antigens. acholeplasma laidlawii showed part ...19938277708
membrane lipid regulation in acholeplasma laidlawii grown with saturated fatty acids. biosynthesis of a triacylglucolipid forming reversed micelles.the membrane lipid composition in several strains of acholeplasma laidlawii is regulated upon a change in the growth conditions. monoglucosyldiacylglycerol (mglcdag) and diglucosyldiacylglycerol (dglcdag) are the most abundant lipids in the a. laidlawii membrane. a third glucolipid, 3-o-acyl-monoglucosyldiacylglycerol (mamglcdag) is synthesized by strain a-ef22 when the membrane lipids contain large amounts of saturated acyl chains. the lipid regulation can be understood from a simple theoretica ...19938344904
phylogenetic diversity of phytopathogenic mycoplasmalike organisms.by using specific primers, the 16s rrna genes of japanese mycoplasmalike organisms (mlos) were amplified by polymerase chain reactions from mlo-enriched fractions of plants infected with each of six different mlos. each of the polymerase chain reaction fragments (length, 1,370 nucleotides) was directly sequenced in both strands by using 17 oligonucleotide primers. a phylogenetic tree constructed by using the sequence data showed that these japanese mlos are phylogenetically diverse microorganism ...19938347505
[inhibitors of nucleic acid synthesis as a means of identifying the forms of dna-dependent dna polymerases in acholeplasma laidlawii pg-8 and of determining their functions].antibiotics, inhibitors of nucleic acids' synthesis from the group of chromomycins (olivomycin of sodium salt), anthracyclines (carminomycin and doxorubicin) and streptonigrin (bruneomycin) have been studied for their effect on dna synthesis in vitro performed by dna polymerases (1st and 2nd forms) of acholeplasma laidlawii pg-8. it has been stated that olivomycin inhibits the function of both the first and second forms of dna polymerases in proportion to an increase of the antibiotic concentrat ...19938355626
regulation and physicochemical properties of the polar lipids in acholeplasma laidlawii. 19938378987
presence of protein constituents of the gram-positive bacterial phosphotransferase regulatory system in acholeplasma laidlawii.acholeplasma species have been reported to lack a functional phosphoenolpyruvate:sugar phosphotransferase system (pts). we show here that acholeplasma laidlawii possesses activities of enzyme i, hpr, hpr(ser) kinase, and hpr(ser-p) phosphatase but lacks detectable activities of enzymes ii of the pts. hpr from this organism was purified, and the regulatory properties of the kinase and phosphatase were characterized and shown to differ from those of previously studied bacteria. the results suggest ...19938407837
cyclodextrins as carriers of cholesterol and fatty acids in cultivation of mycoplasmas.the design of fully or partly defined media for mycoplasma cultivation involves the need to provide the essential lipids, cholesterol and long-chain fatty acids, in an assimilable and nontoxic form. this study introduces cyclodextrins (cds) as carriers of these lipids, thus suggesting alternatives to serum or bovine serum albumin (bsa). the effects of beta-cd and two forms of chemically modified beta-cd, dimethyl-beta-cd (dimeb) and hydroxypropyl-beta-cd (hyprob), on the growth of mycoplasma cap ...19938434920
evidence for two pools of cholesterol in the acholeplasma laidlawii strain b membrane: a deuterium nmr and dsc study.recent investigations have indicated that there exists a well-defined range of membrane hydrocarbon order compatible with good growth of the microorganism acholeplasma laidlawii b [monck, m., bloom, m., lafleur, m., lewis, r. n. a. h., mcelhaney, r. n., & cullis, p. r. (1992) biochemistry 31, 10037-10043]. since cholesterol increases hydrocarbon order in membranes, it was of interest to examine the effect of cholesterol on the hydrocarbon order and growth characteristics of a. laidlawii b. chole ...19938457569
angiotensin ii binding sites on micro-organisms contaminating cell cultures.an angiotensin ii (ang ii) binding site, distinct from at1 and at2, has been found in cell cultures of rat aortic smooth muscle and rat glomerular mesangium. it is characterized by a high affinity for ang ii (kd 0.75 +/- 0.13 nm) and ang i (ki 0.72 +/- 0.12 nm), but a very low affinity for ang iii (ki 31 +/- 5 microm). ang(1-7) (ki 1.01 +/- 0.26 nm) and ang(1-6) (ki 4.54 +/- 0.24 nm) are very selective for this site, with affinities more than 150- and 10,000-fold greater, respectively, than for ...19938469777
phase transitions of acholeplasma laidlawii membranes. the involvement of mg(2+)-atpase in the c transition.highly sensitive differential scanning calorimetry has been employed to study the phase transitions of a. laidlawii membrane. the dsc curves obtained show five distinct transitions between 20 and 80 degrees c which contain a reversible lipid thermotropic transition at about 37 degrees c and four irreversible denaturation transitions of the membrane proteins occurred at about 44 degrees c, 52 degrees c, 62 degrees c, and 67 degrees c, respectively. total enthalpy of the thermal denaturation of me ...19938486158
[the kinetic and functional characteristics of dna-dependent dna-polymerases in acholeplasma laidlawii pg-8].the kinetic and functional characteristics of i and ii forms of dna-dependent dna-polymerases of acholeplasma laidlawii pg-8 have been studied. it is stated that i form of dna polymerase possesses 5'-3'-exonuclease activity and is a typical replicase; ii form of dna-polymerase possesses both 5'-3'-polymerase and 3'-5'-exonuclease activity and is, evidently, a reparase. both forms of enzyme give preference to poly(u)- and poly(a)-matrices having extremely high activity on these polymers. the enzy ...19938497202
quantitative ir studies of acyl chain conformational order in fatty acid homogeneous membranes of live cells of acholeplasma laidlawii b.acholeplasma laidlawii b has been grown highly enriched in myristic, pentadecanoic, and palmitic acids. the conformational order in the acyl chains of living cell membranes has been compared with that in the membranes of lysed cells and the lipids extracted therefrom, using fourier-transform infrared (ft-ir) spectroscopic techniques. a gel-liquid-crystal-phase transition (25-45 degrees c) was noted for both the live cells and the membranes. surprisingly, ch2 wagging progressions, characteristic ...19938512939
[a cell-free translation system based on mollicute ribosomes].active cell-free protein-synthesizing systems are created on the basis of ribosomes of acholeplasma laidlawii var. granulum str. 118, a. laidlawii pg-8 and active lysates of eucaryotic cells (lysate of rabbit reticulocytes and wheat germ extract) in which activity of 80s-ribosomes was suppressed by addition of actidione in concentrations of 150 and 200 mkg/ml, respectively. it is shown that preincubation of active lysates of eucaryotic cells with actidione does not influence their ribosome inhib ...19938025692
[the inhibitory action of 6-azacytidine on mollicutes and its proposed mechanism].6-azacytidine (6-ac) is shown to have an inhibitory effect on the mollicutes of the different systematic position. the growth of type strains of mollicutes (acholeplasma laidlawii pg-8, mycoplasma pneumoniae fh and m. fermentans pg-18) completely ceased in the nutrient medium at concentration of the above substance in it within the range of 125-250 micrograms/ml. 50% inhibiting concentration of 6-ac equaled: for m. fermentans pg-8: 23.43 micrograms/ml; m. pneumoniae fn: 46.8 micrograms/ml; achol ...19937684488
membrane properties of a plant-pathogenic mycoplasmalike organism.in terms of biosystematics, the plant-pathogenic mycoplasmalike organisms (mlos) have been tentatively placed into the class mollicutes. certain physiological tests have been used to distinguish families within this class: the sterol-nonrequiring acholeplasmataceae differ from the sterol-requiring mycoplasmataceae in that the former are more resistant to lysis by digitonin and more sensitive to lysis in hypotonic salt solutions. to test mlos for these membrane properties and thus assist in their ...19921732203
cloning and dna sequence of a mycoplasmal reca gene.mycoplasmas are wall-less prokaryotes phylogenetically related to gram-positive bacteria. in order to investigate dna recombination in these organisms, we have cloned the reca gene from the mycoplasma acholeplasma laidlawii. dna sequence data indicate extensive homology between the a. laidlawii reca gene and reca genes from other bacteria, particularly bacillus subtilis. the reca sequences from three a. laidlawii strains (strains ja1, k2, and 8195) were compared, and surprisingly, the gene from ...19921732213
identification and analysis of the genes coding for the putative pyruvate dehydrogenase enzyme complex in acholeplasma laidlawii.a monospecific antibody recognizing two membrane proteins in acholeplasma laidlawii identified a plasmid clone from a genomic library. the nucleotide sequence of the 4.6-kbp insert contained four sequential genes coding for proteins of 39 kda (e1 alpha, n terminus not cloned), 36 kda (e1 beta), 57 kda (e2), and 36 kda (e3; c terminus not cloned). the n termini of the cloned e2, e1 beta, and native a. laidlawii e2 proteins were verified by amino acid sequencing. computer-aided searches showed tha ...19921735725
membrane protein acylation. preference for exogenous myristic acid or endogenous saturated chains in acholeplasma laidlawii.mycoplasmas are small bacteria without a cell wall, often found as surface parasites on eukaryotic cells. of the more than 200 membrane proteins from acholeplasma laidlawii resolved by two-dimensional page, 23 were covalently modified with acyl chains. these acyl proteins had lower pi values than average and were all labelled by different exogenously supplied radioactive fatty acids attached by o-ester bonds. the fatty acids were selectively incorporated in the order myristic acid (14:0) greater ...19921740134
acholeplasma laidlawii has trna genes in the 16s-23s spacer of the rrna operon.we amplified the 16s-23s rrna intergenic spacer region of acholeplasma laidlawii pg8 by polymerase chain reaction (pcr) and obtained two specific pcr products in different sizes. we have sequenced both pcr products and found that one of them has sequence homologous to the spacer trna genes in bacillus subtilis. this is the first evidence of trna genes between the 16s-23s rrna intergenic spacer regions in members of the class mollicutes.19921281149
[the isolation of ribosomes from acholeplasma and the study of their physicochemical characteristics].ribosomes are produced from acholeplasma laidlawii pg-8 and a. laidlawii var. granulum str. 118. it is proved as possible to use the standard method of differential centrifugation for isolation of mollicute ribosomes. the physico-chemical properties of acholesplasma ribosomes are studied. the protein content for a. laidlawii pg-8 amounted to 39.6%, rrna content--60.4% and for a. laidlawii var. granulum--39.1 and 60.8%, respectively. the rna: protein ratio equals 1.5:1, the ratio of optic density ...19921284088
[identification of mycoplasma by the growth inhibition of samples isolated from cell cultures].cell cultures must be continuously screened for the presence of mycoplasma because, although these microorganisms sometimes pass unnoticed, they may cause chromosomic alterations and interfere with viral replication, antibody and interferon production etc. the international organization for mycoplasmology (iom) recommends the isolation and identification of mycoplasma with a view to the detection of the origin of the infection and the improvement of the quality of the cultures. in this paper, 37 ...19921307416
influence of lipid composition on the orientational order in acholeplasma laidlawii strain b membranes: a deuterium nmr study.2h nmr techniques have recently been developed to determine the complete orientational order profile of lipid bilayers employing lipids containing perdeuteriated palmitic acid [lafleur, m., fine, b., sternin, e., cullis, p.r., & bloom, m. (1989) biophys. j. 56, 1037-1041]. in this work, these techniques have been applied to study order profiles in intact membranes derived from acholeplasma laidlawii strain b. it is shown that complete orientational order profiles can be readily obtained from the ...19921390762
[the effect of physicochemical factors on the activity of dna-dependent dna polymerases in acholeplasma laidlawii pg-8].the biological and physico-chemical properties of dna-dependent dna-polymerases of acholeplasma laidlawii pg-8 have been studied. the optimal parameters of maximal enzymatic activity are determined. it is stated that n-ethylmaleimide in concentration of 1 mm activated dna-polymerase i by 52%, whereas dna-polymerase ii with reagent concentration of 0.5 mm demonstrated the peak of activity exceeding the control only by 10%. spermidine in concentration of 1.5 mm for the first form of dna-polymerase ...19921406382
breeder turkey hens seropositive and culture-negative for mycoplasma synoviae.four flocks of clinically normal turkey breeder hens were shown to have suspect and positive mycoplasma synoviae (ms) hemagglutination-inhibition (hi), enzyme-linked immunosorbent assay, and, in some cases, serum plate agglutination serology in the absence of ms isolation. in all cases, hi serology for mycoplasma gallisepticum (mg) and m. meleagridis was negative. acholeplasma laidlawii was isolated from some hens in each of these ms-seropositive culture-negative flocks. immunoblotting was used ...19921417615
[tubular structures in mycoplasma gallisepticum and the localization of a tubulin-like protein].in all the strains of m. gallisepticum investigated, a protein with apparent molecular weight 40 kda was revealed by immunoblotting with polyclonal anti-calf brain tubulin antibodies and monoclonal anti-chicken alpha-tubulin antibodies. in other 8 investigated mycoplasma species no positive reactions with the same antibodies were found. the m. gallisepticum cells were examined under electron microscope on fine serial sections and on some sections going at different angles to the long cell axis. ...19921440927
[the effect of mycoplasma contamination on the karyotypic structure of a skin fibroblast cell line from the indian muntjac].the karyotypic variability has been studied in a low chromosomal cell line of the indian muntjak skin fibroblasts contaminated with mycoplasma arginini r-16 and acholeplasma laidlawii a. the mycoplasmal contamination exerted influence on the cell distribution for the chromosome number. the frequency of the modal class cells with 7 chromosomes, having the main structure variant of the karyotype (msvk) 2 + 2 + 1 + 1 + 1, was seen to decrease, while the frequency of the submodal class cells with 6 ...19921440934
construction of reca mutants of acholeplasma laidlawii by insertional inactivation with a homologous dna fragment.mycoplasmas (class mollicutes) are wall-less prokaryotes phylogenetically related to gram-positive bacteria. this study describes the construction of reca mutants of the mycoplasma acholeplasma laidlawii. an internal fragment of the reca gene from a. laidlawii was cloned into a plasmid that does not replicate in this organism. when this plasmid construct was used to transform a. laidlawii, it inserted into the chromosome, disrupting the reca gene. the phenotype of the resulting reca mutant was c ...19921461941
the nasal mycoplasmal flora of healthy calves and cows.the nasal mycoplasmal flora of 270 healthy cows from 27 herds in the netherlands and 35 healthy calves from 7 of these herds was examined. various methods for isolating mycoplasmas were compared. the prevalence of the various species was as follows: ureaplasma diversum in 3 (9%) calves; mycoplasma dispar in 14 (40%) calves; m. bovis in 1 (3%) calf; m. bovirhinis in 23 (66%) calves and 16 (6%) cows; m. bovoculi in 8 (23%) calves and 53 (20%) cows; m. canis in 1 (3%) calf; m. equirhinis in 2 (1%) ...19921462726
effect of glycolipids on the phase behavior and dynamic properties of phospholipid liposomes.the glycolipids of acholeplasma laidlawii aih089 membranes were identified and purified. the effect of monoglucosyldiacylglycerol (mgdg) and diglucosyldiacylglycerol (dgdg) on the thermotropic behavior of multilamellar vesicles of dipalmitoylphosphatidylcholine (dppc), dipalmitoylphosphatidylglycerol (dppg) has been investigated by high sensitivity differential scanning calorimetry. the main transition peaks were broadened, the enthalpies were decreased. dgdg caused the decrease in the transitio ...19921510663
the enzymatic synthesis of membrane glucolipids in acholeplasma laidlawii.in membranes of the prokaryote acholeplasma laidlawii, the physiological regulation of the two major membrane lipids, monoglucosyldiacylglycerol (mglcdag) and diglucosyldiacylglycerol (dglcdag), is governed by factors affecting the equilibria between lamellar and non-lamellar phases of the membrane lipids. the synthesis of the glucolipids is considered to be a two-step glucosylation: (i) dag+udp-glc----mglcdag+udp; and (ii) mglcdag+udp-glc----dglcdag+upd. this was corroborated by in vivo pulse l ...19921533160
the effect of cholesterol and epicholesterol on the activity and temperature dependence of the purified, phospholipid-reconstituted (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes.the (na+ + mg2+)-atpase purified from acholeplasma laidlawii b membranes was reconstituted into large, unilamellar vesicles formed from dimyristoylphosphatidylcholine (dmpc) and varying amounts of cholesterol or epicholesterol. the atp hydrolytic activity of the reconstituted enzyme was then determined over a range of temperatures and the phase state of the dmpc in the atpase-containing vesicles was characterized by high-sensitivity differential scanning calorimetry. in the vesicles containing o ...19921535512
evolutionary relationships of a plant-pathogenic mycoplasmalike organism and acholeplasma laidlawii deduced from two ribosomal protein gene sequences.the families within the class mollicutes are distinguished by their morphologies, nutritional requirements, and abilities to metabolize certain compounds. biosystematic classification of the plant-pathogenic mycoplasmalike organisms (mlos) has been difficult because these organisms have not been cultured in vitro, and hence their nutritional requirements have not been determined nor have physiological characterizations been possible. to investigate the evolutionary relationship of the mlos to ot ...19921556079
[the chromatographic properties of the dna-dependent dna polymerases from acholeplasma laidlawii pg-8].the dna-dependent dna-polymerase (dna polymerase i which is not sorbed on the column with deae-cellulose, and dna-polymerase ii, which is absorbed by this column and is eluted from it by 0.3 m of nacl), have been isolated from acholeplasma laidlawii pg-8. dna-polymerase i in homogeneous state was obtained as a result of the stepwise treatment by heparin-sepharose (elution at 0.35 m of nacl) and poly-u-sepharose (elution at 0.3 m of nacl). it was presented on the electrophoregram by one polypepti ...19921584084
[rnase substrate specificity in acholeplasma laidlawii pg-8].a substrate specificity of rnases of a. laidlawii pg-8 to polynucleotides - poly (c), poly (u), poly (a) has been studied. due to the data obtained both intracellular and extracellular rnases of a. laidlawii possess similar specificity to different polynucleotides. both rnases preferentially break cytidine-bonds. specificity of the studied enzymes in respect to polyuridylic and polyadenylic acids was less expressed.19921584085
some observations on mycoplasma-cidal activity of horse serum. 19921606266
behaviour of a glycosphingolipid with unsaturated fatty acid in phosphatidylcholine bilayers.n-(oleoyl)galactosylceramide with perdeuterated acyl chain was prepared by partial synthesis, and studied by wide line 2h-nmr in phospholipid liposomes. spectra were obtained for low glycolipid concentrations in bilayers of dimyristoyl-, distearoyl-, and 1-palmitoyl-2-oleoylphosphatidylcholines. in an attempt to isolate the effects of glycosphingolipid fatty acid cis unsaturation on glycolipid behaviour in membranes, spectral findings related to the above species were compared to literature nmr ...19921616922
isoprenoid modification of proteins distinct from membrane acyl proteins in the prokaryote acholeplasma laidlawii.isoprenylation is an important posttranslational modification that affects the activity, subunit interactions and membrane anchoring of different eukaryotic proteins. the small, cell-wall-less prokaryote acholeplasma laidlawii has more than 20 membrane acyl-proteins enriched in myristoyl and palmitoyl chains. radioactive mevalonate, a precursor to isoprenoids, was incorporated into several specific membrane proteins of 20 to 45 kda and two soluble proteins of 23-25 kda, respectively. no acyl pro ...19921616923
immunological properties of antibodies against mg(2+)-atpase from acholeplasma laidlawii membranes.in the present study, antibodies were raised against the mg(2+)-atpase and the immunological relationships between the enzyme and other atpase from a variety of biological membranes were determined. the anti mg(2+)-atpase antiserum inhibited 85% of the enzyme activity from a. laidlawii membranes. we demonstrate a specific selectivity of mg(2+)-atpase antiserum for antigenic determinants of the a. laidlawii membranes. immunoblot studies of a. laidlawii membrane peptides indicated labeling of five ...19911714730
evolution of trnas and trna genes in acholeplasma laidlawii.the genes for 22 trna species from acholeplasma laidawii, belonging to the class mollicutes (mycoplasmas), have been cloned and sequenced. sixteen genes are organized in 3 clusters consisting of eleven, three and two trna genes, respectively, and the other 6 genes exist as a single gene. the arrangement of trna genes in the 11-gene, the 3-gene and the 2-gene clusters reveals extensive similarity to several parts of the 21-trna or 16-trna gene cluster in bacillus subtilis. the 11-gene cluster is ...19911722304
[the stability of the alkylating derivatives of oligodeoxyribonucleotides containing a cholesterol or phenazine radical added to the 3'-termination during their interaction with acholeplasma laidlawii pg-8].stability of alkylating derivatives of decathymidylates protected on the 3'-terminal by cholesterol and phenazine residues has been studied in the process of their interaction with cells of acholeplasma laidlawii pg-8. it is shown that the studied reagents are not split by nucleases of a. laidlawii pg-8 for the time necessary for alkylation of mycoplasma biopolymers.19911753886
[the interaction of alkylating derivatives of oligodeoxyribonucleotides and their methylphosphonate analogs with mycoplasma cells].alkylating derivatives of decathymidylates and methylphosphonate analogs of oligodeoxyribonucleotides (mpao) were studied for their interaction with cells of acholeplasma laidlawii pg-8, mycoplasma capricolum california kid, m. pneumoniae fh and phytopathogenic strain (st. 118). it is shown that mpao of octa- and hexadecathymidylates as well as decathymidylates 3'-terminal modified by phenazine and cholesterol groupings are sorbed by mycoplasma cells and can penetrate inside the cells. efficienc ...19911753887
identification of porcine mycoplasmas using commercial enzyme assay systems. 19911760468
[cross reactive antigens of acholeplasma laidlawii and l-form of staphylococcus aureus].we demonstrated that the membrane of acholeplasma laidlawii pg8 and l-form of staphylococcus aureus, both of which induce cellular immunity in balb/c mice, were antigenically related each other. foodpad responses of the mice immunized with a mixture of either antigen and freund's complete adjuvant showed clearly a cross reaction when challenged with the other antigen. cross responses to incorporate 3h-thymidine to the spleen lymphocytes of the mice immunized with either antigen occurred in the p ...19911762175
chloride fluxes across acholeplasma laidlawii membranes.chloride fluxes across the cytoplasmic membrane of acholeplasma laidlawii were studied by using the chloride sensitive fluorescent dye, 6-methoxy-n-(sulfopropyl)quinolinium. chloride was found to penetrate the membrane passively. chloride flux was dependent upon the transmembrane electric potential.19911778416
[the isolation and partial purification of 2 dna-dependent dna polymerases from acholeplasma laidlawii pg-8].two forms of dna-dependent dna-polymerase have been isolated and partially purified from the limited amount of biomass of cells acholeplasma laidlawii pg-8, a typical representative of genus acholeplasmataceae, as a result of successive chromatography on the columns with deae-cellulose de-52 and green a-sepharose. the first form of dna-polymerase is eluted from the ion-exchange column with nacl concentration of 0.1 m from the column with green a-sepharose of 0.27 m, while the second form-with na ...19911791778
[the rnases of the mollicute acholeplasma laidlawii pg-8: its detection and accumulation dynamics]. 19911791779
comparison of glycoproteins from ten human mycoplasma species.multiple bands of glycoprotein, rare in procaryotes, were detected in ten human mycoplasma species by staining with periodic acid-schiff (pas) reagent after sodium dodecyl sulphate-polyacrylamide gel electrophoresis (sds-page). a major contaminant formed in hayflick medium (h medium), corresponding to an apparent molecular weight of about 80 kd, was eliminated by using the organisms grown in pplo broth supplemented with pplo serum fraction (p medium), except that m. genitalium and m. pneumoniae ...19911815100
mystery swine disease in the netherlands: the isolation of lelystad virus.in early 1991, the dutch pig-industry was struck by the so-called mystery swine disease. large-scale laboratory investigations were undertaken to search for the etiological agent. we focused on isolating viruses and mycoplasmas, and we tested paired sera of affected sows for antibodies against ten known pig viruses. the mycoplasmas m. hyosynoviae, m. hyopneumoniae, and acholeplasma laidlawii, and the viruses encephalomyocarditis virus and porcine enterovirus types 2 and 7 were isolated from indi ...19911835211
interaction of modified oligonucleotides with eukaryotic and mycoplasma cells and their fate inside the cells. 19911841342
continuous distribution of mycoplasma genome sizes.genome sizes of eleven strains of eight species of mollicutes mycoplasmataceae were investigated by pulsed-field gel electrophoresis. mycoplasma genomic sizes were determined from the sum of the sizes of fragments obtained after digestion of genomic dna with restriction endonucleases. the sizes of the fragments were determined by comparison of their electrophoretic mobilities with those of lambda dna concatemers. specific restriction endonucleases were chosen so that after digestion three to ten ...19911841633
[the thermodynamic parameters of the conformational transitions in mycoplasma dna].dna preparations have been isolated from 10 strains of phytopathogenic mycoplasms and collection culture achole plasma laidlawii pg-8. thermodynamic parameters of denaturation changes in the secondary structure (transconformation) of dna of these mycoplasms have been determined. it is shown that denaturation temperature is 82.3-83.1 degree c and enthalpy of conformational dna transitions calculated per 1 g of dry substance is 56.2-61.9 j/g. changes in the enthalpy (delta h) and entropy (delta s) ...19911861653
search for eukaryotic motility proteins in spirochetes: immunological detection of a tektin-like protein in spirochaeta halophila.the serial endosymbiotic theory (set) for the spirochete origin of undulipodia (cilia and eukaryotic flagella) predicts that a greater number of axonemal proteins will show homology to spirochete than to other bacterial proteins. to continue testing, the set proteins associated with eukaryotic motility (tektin, centrin and calmodulin) were sought in spirochaeta halophila. western blot immunological detection techniques (for tektin and centrin) and two-dimensional gel analysis (for calmodulin) we ...19911863720
[contamination of fish tissue cell cultures by mycoplasma].the inoculated and primary cell cultures of fish (carp, salmon, and sturgeon) have been studied. acholeplasma typed as a. laidlawii in terms of its biochemical properties shown in inhibited metabolism has been isolated from 19 samples. the authors consider the source of acholeplasma-induced contamination of the cell cultures under study.19911927041
fusion of mycoplasmas: the formation of cell hybrids.poly(ethylene glycol) (peg 8000) can induce cell-cell fusion of mycoplasma capricolum cells, and it can promote the formation of intergeneric hybrids of various mycoplasma, acholeplasma and spiroplasma species. the extent of fusion was quantitatively evaluated by following the dequenching of octadecylrhodamine fluorescent label incorporated into donor cell membranes after their incubation with recipient cells. the results of dequenching experiments were confirmed by electron microscopy, as well ...19911936938
the genome size of a plant-pathogenic mycoplasmalike organism resembles those of animal mycoplasmas.the genome size of a mycoplasmalike organism was determined by comparing fluorescence intensities of restriction fragments. its genome size was similar to that of mycoplasma gallisepticum and much smaller than that of acholeplasma laidlawii. although the genome size is "mycoplasmalike," other molecular data indicate a closer evolutionary relationship to a. laidlawii.19912002012
evidence that mycoplasmas, gram-negative bacteria, and certain gram-positive bacteria share a similar protein antigen.it was demonstrated that mycoplasmas, gram-negative bacteria, and certain gram-positive bacteria share a similar protein antigen with a molecular weight ranging from 42,000 to 48,000. western blotting (immunoblotting) with an antibody specific to a 43-kda membrane protein of mycoplasma fermentans showed the existence of this protein antigen in all mycoplasma spp. tested (14 species), acholeplasma laidlawii (1 strain), and gram-negative bacteria (8 species) but only in staphylococcus aureus of fo ...19912007558
order and dynamics in mixtures of membrane glucolipids from acholeplasma laidlawii studied by 2h nmr.the two dominant glucolipids in acholeplasma laidlawii, viz., 1,2-diacyl-3-o-(alpha-d-glucopyranosyl)-sn-glycerol (mglcdg) and 1,2-diacyl-3-o-[alpha-d-glucopyranosyl-(1----2)-o-alpha-d-glucopyranosyl ]- sn-glycerol (dglcdg), have markedly different phase behavior. mglcdg has an ability to form nonlamellar phases, whereas dglcdg only forms lamellar phases. for maintenance of a stable lipid bilayer, the polar headgroup composition in a. laidlawii is metabolically regulated in vivo, in response to ...19912036360
[the interaction of the rna-polymerases of a phytopathogenic strain of mycoplasma with oligodeoxyribonucleotides associated with gene promoter regions]. 19902090419
evaluation of different hybridization procedures for the detection of mycoplasma contamination in cell cultures.cell culture samples were analysed for mycoplasma contaminations with two different dna probes which have been described earlier. one probe (the h900 probe), derived from the 23s rrna gene of mycoplasma hyorhinis, cross-hybridized with virtually all mycoplasmas (including the acholeplasmas). the other probe (the t2 probe), derived from a protein gene of acholeplasma laidlawii, cross-hybridized with most acholeplasmas. the two probes were compared in three different direct filter hybridization pr ...19902107395
glycosidase activities of mycoplasmas.the activities of alpha- and beta-glucosidase, beta-galactosidase and beta-n acetylglucosaminidase were assessed at acidic ph by fluorimetry using the appropriate 4-methylumbelliferyl substrate in four mycoplasma species (m. pneumoniae, m. gallisepticum, m. hominis and m. capricolum) and in acholeplasma laidlawii. the glycosidase activities were in a low range (0.1-4.2 nmole per h per mg protein) with the exception of higher activities of beta-n-acetylglucosaminidase in a. laidlawii. the enzyme ...19902119590
studies on the purified na+,mg(2+)-atpase from acholeplasma laidlawii b membranes: a differential scanning calorimetric study of the protein-phospholipid interactions.the purified na+,mg2(+)-atpase from the acholeplasma laidlawii b plasma membrane was reconstituted with dimyristoyl phosphatidylcholine and the lipid thermotropic phase behavior of the proteoliposomes formed was investigated by differential scanning calorimetry. the effect of this atpase on the host lipid phase transition is markedly dependent on the amount of protein incorporated. at low protein/lipid ratios, the presence of increasing quantities of atpase in the proteoliposomes increases the t ...19902140945
genetic exchange of transposon and integrative plasmid markers in mycoplasma pulmonis.matings of genetically marked derivatives of mycoplasma pulmonis resulted in the exchange of chromosomal dna and the appearance of doubly marked transconjugants. transposons tn916 and tn4001, and a series of integrative plasmids derived from their cloned antibiotic resistance genes, were used to construct antibiotic-resistant mycoplasmal derivatives to examine this phenomenon at the molecular level. genetic exchange occurred on agar surfaces at frequencies ranging from 3.3 x 10(-4) to 6.4 x 10(- ...19902158966
terminal redundancy and circular permutation of mycoplasma virus l3 dna.this communication reports the physical map of mycoplasma virus l3 (mv-l3) dna derived from restriction patterns obtained by digestion with seven different restriction endonucleases. the length of the restriction map is 36,200 bp in contrast to the contour length of native mv-l3 dna molecules which is 39,400 bp as determined by electron microscopy. the difference in length of 3,200 bp (corresponding to 8.1% of the native viral dna contour length) is explained by terminal redundancy. it was possi ...19902212995
ageing of procaryotes. acholeplasma laidlawii as an object for cell ageing studies: a brief note.it was established that a. laidlawii cell viability in the stationary phase of culture development decreases according to the gompertz law. it was shown that the "stationary" ageing of a. laidlawii cells is accompanied by the lower intensity of phosphorus-containing compounds biosynthesis, decreased rate of membrane proteins synthesis and degradation and also by accumulation of dna single-strand breaks. the biochemical changes found in ageing a. laidlawii cells are similar to ageing manifestatio ...19902214893
pulse-field electrophoresis indicates full-length mycoplasma chromosomes range widely in size.full-size linear chromosomes were prepared from mycoplasmas by using gamma-irradiation to introduce one (on average) double-strand break in their circular chromosomes. chromosome sizes were estimated by pulsed-field gel electrophoresis (pfge) from the mobilities of these full-length molecules relative to dna size references. sizes estimated for ureaplasma urealyticum t960 and 16 mycoplasma species ranged from 684 kbp (m. hominis) to 1315 kbp (m. iowae). using this sample, we found no correlation ...19902216718
effects of age, environmental temperature and relative humidity on the colonization of the nose and trachea of calves by mycoplasma spp.nasal and tracheal swabs sequentially collected from three groups of eight calves between the ages of 1 and 98 days indicated that the nose and trachea were colonized by mycoplasma spp. during the first weeks of life. over 92% of all calves harboured mycoplasma spp. in their noses when they were 2 weeks old, the rate of recovery falling gradually thereafter. the peak period of recovering mycoplasmas from the noses and tracheas of calves was at 6 weeks old. m. bovirhinis, m. arginini and acholepl ...19902224487
cholesterol accumulation in plasma membrane and changes of membrane enzyme activity of acholeplasma laidlawii cells during culture ageing.the data presented in this report show that the microviscosity of the plasma membrane and the cholesterol/phospholipid molar ratio of its lipid bilayer increases during ageing of acholeplasma laidawii cultures. at the same time the age changes of other lipid components content do not correlate with the change of membrane viscosity. it is also shown that membrane enzyme activities of mycoplasma cell decrease with age. these results confirm the membrane hypothesis of ageing according to which incr ...19902232909
differences in accumulation of radiolabeled amino acids and polyamines by mycoplasma and acholeplasma species.four species in the order mycoplasmatales, mycoplasma capricolum, mycoplasma hominis, mycoplasma arginini, and acholeplasma laidlawii, were compared for their ability to accumulate radiolabeled amino acids and polyamines. the use of a novel high-molecular-weight (hmw) medium, from which molecules of less than 12,000 molecular weight had been removed by extensive dialysis, allowed us to discern significant differences among the species in their relative accumulations of [3h]methionine and [3h]leu ...19902275861
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