| endonuclease from acholeplasma laidlawii strain ja1 associated with in vivo restriction of dna containing 5-methylcytosine. | transfection of acholeplasma laidlawii strain ja1 with viral dnas that have been sequence-specifically methylated in vitro has led us to previously postulate that ja1 cells contain an enzyme which cleaves only dna containing 5-methylcytosine, regardless of the nucleotide sequence containing that base. in this paper we show that an endonuclease activity is present in extracts from ja1 cells but not in extracts from a restriction-deficient variant of ja1. the partially purified enzyme cleaves not ... | 1987 | 2822609 |
| animal viruses are able to fuse with prokaryotic cells. fusion between sendai or influenza virions and mycoplasma. | sendai and influenza virions are able to fuse with mycoplasmata. virus-mycoplasma fusion was demonstrated by the use of fluorescently labeled intact virions and fluorescence dequenching, as well as by electron microscopy. a high degree of fusion was observed upon incubation of both virions with mycoplasma gallisepticum or mycoplasma capricolum. significantly less virus-cell fusion was observed with acholeplasma laidlawii, whose membrane contains relatively low amounts of cholesterol. the require ... | 1988 | 2826447 |
| purification of membrane proteins in sds and subsequent renaturation. | a prerequisite for the purification of any protein to homogeneity is that the protein is not non-specifically associated with other proteins especially during the final stage(s) of the fractionation procedure. this requirement is not so often fulfilled when nonionic detergents (for instance triton x-100) are used for solubilization of membrane proteins. the reason is that these detergents are not efficient enough to prevent the protein of interest from forming aggregates with other proteins upon ... | 1988 | 2833310 |
| enzymological features of aromatic amino acid biosynthesis reflect the phylogeny of mycoplasmas. | acholeplasma laidlawii possesses a biochemical pathway for tyrosine and phenylalanine biosynthesis, while mycoplasma iowae and mycoplasma gallinarum do not. the detection of 7-phospho-2-dehydro-3-deoxy-d-arabino-heptonate (dahp) synthase (ec 4.1.2.15), dehydro-shikimate reductase (ec 1.1.1.25) and 3-enol-pyruvoylshikimate-5-phosphate synthase (ec 2.5.1.19) activities in cell-free extracts established the presence in a. laidlawii of a functional shikimate pathway. l-phenylalanine synthesis occurs ... | 1987 | 2895162 |
| evaluation of a digitonin disk assay to discriminate between acholeplasma and mycoplasma isolates from bovine milk. | a study was undertaken to evaluate effectiveness of a digitonin disk inhibition test to discriminate between acholeplasma laidlawii and mycoplasma sp. isolated from bovine milk. the test measured zone diameters of growth inhibition surrounding a digitonin-containing disk on solid medium. zones of inhibition for 20 isolates of a. laidlawii, ranging from 8-14 mm, did not overlap those of 261 isolates of mycoplasma sp., ranging from 16 to 38 mm. examination of variation in zone diameters for m. bov ... | 1989 | 2912675 |
| reconstitution and photolabeling of the purified (na+ + mg2+)-atpase from the plasma membrane of acholeplasma laidlawii b with phospholipids containing a photosensitive fatty acyl group. | the purified membrane (na+ + mg2+)-atpase of acholeplasma laidlawii b was reconstituted into vesicles composed of phospholipids containing a photoactivatable aryl nitrene-generating fatty acyl group. the reconstitution with phospholipid resulted in an enhancement of atpase activity and a reduction in the sensitivity of the enzyme to radiation inactivation. the incorporation of the enzyme into the lipid vesicles results in a broadening of the gel-to-liquid-crystalline phase transition of the phot ... | 1985 | 2933074 |
| structure-function investigations of the membrane (na+ + mg2+)-atpase from acholeplasma laidlawii b: studies of reactive amino acid residues using group-specific reagents. | the purified, lipid-reconstituted (na+ + mg2+)-atpase from acholeplasma laidlawii b was treated with a variety of reagents which specifically modify various amino acid residues on the enzyme. in all cases reaction of this enzyme with any of the reagents tested results in at least a partial inactivation of its activity. the modification of one reactive lysine by dinitrofluorobenzene, of one reactive arginine by phenylglyoxal, or of two tyrosine residues by 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole ... | 1986 | 2939801 |
| reconstitution of the purified (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes into lipid vesicles and a characterization of the resulting proteoliposomes. | the purified (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes was reconstituted with dimyristoylphosphatidylcholine using a cholate solubilization and dialysis procedure. the incorporation of this enzyme into the phospholipid bilayer is accompanied by an enhancement of its specific activity and by a restoration of its lipid phase state-dependent properties which were lost during solubilization and purification from native membranes. moreover, reconstitution of this atpase with phospho ... | 1987 | 2958088 |
| lipid modulation of the activity and temperature dependence of the purified (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes. | the influence of lipid composition on the activity and temperature dependence of the purified (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes has been investigated. the reconstituted enzyme requires liquid-crystalline lipid for full activity. however, phosphatidylcholines with fatty acids varying considerably in chemical structure and chain length all support comparable levels of activity at temperatures above their gel to liquid-crystalline phase transition temperatures, indicating ... | 1987 | 2959635 |
| method for exchange of the lipid environment of the membrane-bound (mg2+ + na+)-atpase of acholeplasma laidlawii b. | a method that exchanges the endogenous lipids in the environment of the membrane-bound (mg2+ + na+)-atpase of acholeplasma laidlawii b with defined exogenous lipids has been devised. results demonstrate that 99.9% of the original membrane lipids were replaced with phosphatidylcholine and phosphatidic acid. atpase enzyme activity was maintained throughout the substitution procedure. | 1987 | 2960250 |
| characterization of sodium transport in acholeplasma laidlawii b cells and in lipid vesicles containing purified a. laidlawii (na+-mg2+)-atpase by using nuclear magnetic resonance spectroscopy and 22na tracer techniques. | the active transport of sodium ions in live acholeplasma laidlawii b cells and in lipid vesicles containing the (na+-mg2+)-atpase from the plasma membrane of this microorganism was studied by 23na nuclear magnetic resonance spectroscopic and 22na tracer techniques, respectively. in live a. laidlawii b cells, the transport of sodium was an active process in which metabolic energy was harnessed for the extrusion of sodium ions against a concentration gradient. the process was inhibited by low temp ... | 1988 | 2973459 |
| spiroplasma membrane lipids. | membranes of six spiroplasma strains belonging to different spiroplasma species and subgroups were isolated by a combination of osmotic lysis and sonication in the presence of edta to block endogenous phospholipase activity. analysis of membrane lipids showed that in addition to free and esterified cholesterol the spiroplasmas incorporated exogenous phospholipids from the growth medium. sphingomyelin was preferentially incorporated from phosphatidylcholine-sphingomyelin vesicles or from the seru ... | 1985 | 2981796 |
| identification of an enveloped phage, mycoplasma virus l172, that contains a 14-kilobase single-stranded dna genome. | we have found that mycoplasma virus l172 is an enveloped globular virion containing circular, single-stranded dna of 14.0 kilobases. l172 has been reported by other workers to have a double-stranded dna genome of 13 to 17 kilobase pairs and has been classified as a plasmavirus, a group for which mycoplasma virus l2 is the type member. mycoplasma viruses l172 and l2 differ in genome size and structure, dna base composition, and protein composition, and they have no detectable dna homology. as the ... | 1985 | 2982026 |
| effect of positively charged local anesthetics on a membrane-bound phosphatase in acholeplasma laidlawii. | the plasma membrane p-nitrophenylphosphatase activity of acholeplasma laidlawii was stimulated by the spin-labeled local anesthetic 2-[n-methyl-n-(2,2,6,6-tetramethylpiperidinooxyl)]ethyl p-hexyloxybenzoate, abbreviated as c6sl, and its methylated quaternary analog, c6slmei. the tertiary amine c6sl (at a concentration of 5 x 10(-5) m) was more potent at ph 6.5 than at ph 7.7. in contrast, the permanently-charged c6slmei was equally potent, independently of ph. these results suggest that cationic ... | 1985 | 2988562 |
| mycoplasma restriction: identification of a new type of restriction specificity for dna containing 5-methylcytosine. | mycoplasma bacteriophage l51 single-stranded dna and l2 double-stranded dna are host cell modified and restricted when they transfect acholeplasma laidlawii ja1 and k2 cells. the l51 genome has a single restriction endonuclease mboi site (recognition sequence gatc), which contains 5-methylcytosine when the dna is isolated from l51 phage grown in k2 cells but is unmethylated when the dna is from phage grown in ja1 cells. this gatc sequence is nonessential, since an l51 mutant in which the mboi si ... | 1986 | 3001023 |
| ppi-dependent phosphofructotransferase (phosphofructokinase) activity in the mollicutes (mycoplasma) acholeplasma laidlawii. | a ppi-dependent phosphofructotransferase (ppi-fructose 6-phosphate 1-phosphotransferase, ec 2.7.1.90) which catalyzes the conversion of fructose 6 phosphate (f-6-p) to fructose 1,6-bisphosphate (f-1, 6-p2) was isolated from a cytoplasmic fraction of acholeplasma laidlawii b-pg9 and partially purified (430-fold). ppi was required as the phosphate donor. atp, datp, ctp, dctp, gtp, dgtp, utp, dutp, itp, ttp, adp, or pi could not substitute for ppi. the ppi-dependent reaction (2.0 mm ppi) was not al ... | 1986 | 3001032 |
| effects of mercury (ii) compounds on the activity of dutpases from various sources. | the deoxyuridine triphosphate nucleotidohydrolases (dutpases, ec 3.6.1.23) from escherichia coli k-12-,acholeplasma laidlawii b-pg9-, human kb cell-, and the herpes simplex virus (hsv) type 1- and 2-induced dutpases were purified and used to determine the effect of various mercury (ii) compounds on their activities. mercuric acetate, 5-mercuri-dutp (hgdutp), and 5-mercuri-dctp (hgdctp) acted as irreversible active site-directed inhibitors of the dutpases purified from eukaryotic organisms but no ... | 1986 | 3005836 |
| lipid acyl chain-dependent effects of sterols in acholeplasma laidlawii membranes. | acholeplasma laidlawii was grown with different fatty acids for membrane lipid synthesis (saturated straight- and branched-chain acids and mono- and di-unsaturated acids). the ability of 12 different sterols to affect cell growth, lipid head group composition, the order parameter of the acyl chains, and the phase equilibria of in vivo lipid mixtures was studied. the following two effects were observed with respect to cell growth: with a given acyl chain composition of the membrane lipids, growth ... | 1987 | 3027049 |
| [role of the membranes in lymphocyte interaction with mycoplasmas]. | the interaction of acheleplasma laidlawii cells, derived membranes and liposomes with mouse spleen lymphocytes does not require the energy and participation of electrostatic coupling. the absence of pinocytosis of mycoplasma is demonstrated. specific membrane receptors don't participate in mycoplasma and lymphocyte binding. the exchange by membrane lipids occurs during the interaction of mycoplasma, membranes and liposomes with lymphocytes; mycoplasma, membranes and liposomes lose saturated fat ... | 1986 | 3028509 |
| transposition of gram-positive transposon tn916 in acholeplasma laidlawii and mycoplasma pulmonis. | mycoplasma genetics has been limited by a lack of genetic tools such as selectable markers, methods to transfer dna, and suitable vectors for cloning. studies were undertaken to examine the potential of using the streptococcal transposon tn916 as a mycoplasma genetic tool. the escherichia coli plasmid pam120, which contains tn916, was transformed into acholeplasma laidlawii and mycoplasma pulmonis. transposition of tn916 into the mycoplasma chromosome apparently occurred by an excision-insertion ... | 1987 | 3029869 |
| chromosome analysis by two-dimensional fingerprinting. | a two-dimensional fingerprinting technique has been developed that allows large, cell genome-size dna's to be analyzed by restriction endonuclease cleavage and separation of dna fragments by agarose gel electrophoresis. equations have been derived to determine the genome size and number of cleavage sites from analysis of the distribution of fragment lengths. genome sizes of escherichia coli strain jm101 and two strains of the mycoplasma acholeplasma laidlawii measured by this method are in agree ... | 1986 | 3032749 |
| synthesis of deoxyribomononucleotides in mollicutes: dependence on deoxyribose-1-phosphate and ppi. | cell extracts of acholeplasma laidlawii b-pg9, acholeplasma morum s2, mycoplasma capricolum 14, and mycoplasma gallisepticum s6 were examined for 37 cytoplasmic enzyme activities involved in the salvage and biosynthesis of purines. all of these organisms had adenine phosphoribosyltransferase activity (ec 2.4.2.7) and hypoxanthine phosphoribosyltransferase activity (ec 2.4.2.8). all of these organisms had purine-nucleoside phosphorylase activity (ec 2.4.2.1) in the synthetic direction using ribos ... | 1987 | 3038846 |
| identification of mycoplasma hyopneumoniae in formalin-fixed porcine lung, using an indirect immunoperoxidase method. | an indirect immunoperoxidase staining technique was evaluated for detection of mycoplasma hyopneumoniae in formalin-fixed, paraffin-embedded porcine lung. lungs from swine with induced (n = 4) or naturally occurring m hyopneumoniae infection (n = 31) were examined grossly, by light and immunofluorescent microscopy, and by an indirect immunoperoxidase test, using antibody raised in swine against m hyopneumoniae as the primary antibody. organisms stained by the indirect immunoperoxidase method wer ... | 1988 | 3056138 |
| [decontamination of continual cell lines spontaneously infected with mycoplasmas]. | the continual cell lines of bovine kidneys mdbk and aubek, and porcine kidneys rpd and ibrs, spontaneously infected with mycoplasma arginini and acholeplasma laidlawii, were decontaminated by the method of selective elimination. two elimination procedures were modified to be used for the decontamination: one based on the reduction of infection by the light treatment of the cultures, the other based on the selection of mycoplasma-free cell population through cell clonation. on the basis of a long ... | 1986 | 3090766 |
| [dependence of membrane protein turnover in mycoplasma cells on the age of the culture]. | to understand the molecular mechanisms of damages appearing in biological membranes in the process of cellular aging, changes in the rate of catabolic processes in mycoplasma cells have been studied. this study has revealed that the aging of acholeplasma laidlawii culture is accompanied by a decrease in the activity of such catabolic enzymes as dna-ase, rna-ase, cathepsin d and beta-glucosidase. a considerable increase in the duration of the half-life of membrane proteins has been registered, wh ... | 1987 | 3113136 |
| acholeplasma laidlawii b-pg9 adenine-specific purine nucleoside phosphorylase that accepts ribose-1-phosphate, deoxyribose-1-phosphate, and xylose-1-phosphate. | an adenylate-specific purine nucleoside phosphorylase (purine nucleoside:orthophosphate ribosyltransferase, ec12.4.2.1) (pnp) was isolated from a cytoplasmic fraction of acholeplasma laidlawii b-pg9 and partially purified (820-fold). this partially purified pnp could only ribosylate adenine and deribosylate adenosine and deoxyadenosine. the a. laidlawii partially purified pnp could not use hypoxanthine, guanine, uracil, guanosine, deoxyguanosine, or inosine as substrates, but could use ribose-1- ... | 1988 | 3123458 |
| presence of anaplerotic reactions and transamination, and the absence of the tricarboxylic acid cycle in mollicutes. | cell extracts of the fermentative mollicutes acholeplasma laidlawii b-pg9, acholeplasma morum s2, mycoplasma capricolum 14, mycoplasma gallisepticum s6, mycoplasma pneumoniae fh, mycoplasma hyopneumoniae j and m. genitalium g-37, and the non-fermentative mycoplasma hominis pg-21, mycoplasma hominis 1620 and mycoplasma bovigenitalium pg-11 were examined for 39 cytoplasmic enzyme activities associated with the tricarboxylic acid (tca) cycle, transamination, anaplerotic reactions and other enzyme a ... | 1988 | 3141576 |
| survey of mycoplasma infections in cell cultures and a comparison of detection methods. | a total of 1424 cell cultures was assayed for mycoplasmas by microbiological culture and fluorescent dna staining. of these cultures, 412 (29%) were infected with mycoplasmas. the most frequently occurring mycoplasma species were mycoplasma orale (34%), m. hyorhinis (26%), m. arginini (21%), m. fermentans (13%) and acholeplasma laidlawii (5%). a few isolates each of m. hominis, m. pulmonis and m. bovis were also detected. when detection methods were compared, microbiological culture produced fal ... | 1988 | 3146169 |
| affinity labeling of the (na+ + mg2+)-atpase from acholeplasma laidlawii b membranes by the 2',3'-dialdehyde derivative of adenosine 5'-triphosphate. | the (na+ + mg2+)-atpase of the acholeplasma laidlawii b plasma membrane was inactivated by the 2',3'-dialdehyde derivative of atp (oatp). oatp behaved as a reversible competitive inhibitor of this atpase and was slowly hydrolyzed by the enzyme. in addition, oatp induced an irreversible inactivation of the enzyme. a 62% inactivation of the enzyme correlated with the binding of 16 moles of oatp per mole of the enzyme. in the presence of 5'-adenylyl imidodiphosphate, a non-hydrolyzable substrate an ... | 1985 | 3155967 |
| structural relatedness of three ion-transport adenosine triphosphatases around their active sites of phosphorylation. | three membrane-bound adenosine triphosphatases were investigated for homology in the sequence of four amino acids about the active site of phosphorylation. the atpases were as follows: sodium-potassium-dependent atpase from dog kidney, na,k-atpase; hydrogen-potassium-dependent atpase from hog gastric mucosa, h,k-atpase, an atpase similar to na,k-atpase; and an atpase activity in the plasma membrane of corn, zea mays, roots (cr-atpase), a higher plant atpase. a membrane preparation containing an ... | 1985 | 3156136 |
| the effect of variations in growth temperature, fatty acid composition and cholesterol content on the lipid polar head-group composition of acholeplasma laidlawii b membranes. | we have systematically investigated the effect of variations in growth temperature, fatty acid composition and cholesterol content on the membrane lipid polar headgroup composition of acholeplasma laidlawii b. two important lipid compositional parameters have been determined from such an analysis. the first parameter studied was the ratio of the two major neutral glycolipids of this organism, monoglucosyldiacylglycerol (mgdg) and diglucosyldiacylglycerol (dgdg). as the former lipid prefers to ex ... | 1988 | 3191126 |
| infrared spectroscopic studies of acholeplasma laidlawaii b membranes. comparison of the gel to liquid-crystal phase transition in intact cells and isolated membranes. | the physical state of the membrane lipids in the plasma membranes of intact, live acholeplasma laidlawii b cells was probed by fourier-transform infrared spectroscopy and compared with that in isolated membranes. infrared spectra of live a. laidlawii b cells, enriched biosynthetically in the presence of avidin, with saturated deuterated and unsaturated non-deuterated fatty acids have been recorded at a variety of temperatures. the results indicate that within the temperature range of the gel to ... | 1988 | 3208762 |
| [isolation, chromatographic characteristics and subunit structure of the dna-dependent rna-polymerase of acholeplasma laidlawii pg-8]. | | 1988 | 3249581 |
| cloning and expression of acholeplasma laidlawii membrane acyl proteins in escherichia coli. | many integral membrane proteins in acholeplasma laidlawii are enriched in hydrophilic amino acid residues and covalently modified with fatty acids. in order to understand how these proteins are inserted and anchored in the bilayer, we have cloned several of the major a. laidlawii proteins in escherichia coli: 900 recombinant clones containing 4-kbp dna fragments, inserted into the bamhi site of the plasmid pat 153, were screened with antibodies. with antimembrane antibodies, 26 positive clones w ... | 1987 | 3312093 |
| [detection and identification of mycoplasma infections by dna hybridization]. | infection of cell cultures by mycoplasmas can be detected by hybridization of the dna of suspected cell cultures with recombinant plasmids containing fragments of the mycoplasma dna. the test is very sensitive and allows detection of as little as 1 ng of mycoplasmal dna, roughly equivalent to the dna amount of 10(6) mycoplasmas. this approach turns out to be effective for detection and identification of mycoplasmas in clinical material, plant and insect tissues. a set of dna probes for detection ... | 1987 | 3318046 |
| [self-inactivation of nadh-oxidase from mycoplasma cells during reaction]. | the feasibility of self-inactivation of nadh-oxidase by plasma membranes of acholeplasma laidlawii cells was investigated. it was demonstrated that the rate of nadh oxidation in a flow reactor upon stirring diminishes with time. this decrease of the reaction rate is not coupled with the presence in the reaction mixture of the reaction products--nad+ and h2o2, and is irreversible. in the absence of nadh the enzyme activity is unaffected. the data obtained suggest that nadh-oxidase is inactivated ... | 1988 | 3358960 |
| distinction of species and strains of mycoplasmas (mollicutes) by genomic dna fingerprints with an rrna gene probe. | genomic fingerprints of acholeplasma laidlawii, mycoplasma hominis, and mycoplasma pneumoniae strains were obtained by southern blot hybridization of the digested mycoplasmal dnas with an rrna gene probe. the hybridization patterns revealed genotypic heterogeneity among a. laidlawii and m. hominis strains and a remarkable degree of homogeneity among m. pneumoniae strains isolated from pneumonia patients during a 10-year period. genomic fingerprints with the rrna gene probe can thus serve as indi ... | 1988 | 3384931 |
| electroporation-mediated transfection of acholeplasma laidlawii with mycoplasma virus l1 and l3 dna. | in contrast to mycoplasma virus l1 and l2 circular dna, mycoplasma virus l3 linear dna is not biologically active in polyethylene glycol-mediated transfection. electroporation of acholeplasma laidlawii, however, leads to plaque formation after incubation with l3 dna. the efficiency of electroporation-mediated transfection is 1/10 that of polyethylene glycol-mediated transfection as estimated with l1 dna. trypsin treatment of cells before dna addition increases the efficiency of dna uptake. | 1988 | 3392773 |
| anti-mycoplasmal activity of a new macrolide: miocamycin. | the object of this study was the evaluation of the activity of miocamycin and other macrolides (erythromycin and josamycin) against 61 ureaplasma urealyticum, 1 acholeplasma laidlawii and 21 aerobe mycoplasmas (m. pneumoniae, m. hominis, m. gallisepticum, m. mycoides) and anaerobe mycoplasmas (m. morale and m. salivarium) both clinically isolated and standard reference strains. the minimum inhibitory concentrations (mic) values for miocamycin ranged between 0.00625 mg/l and 0.4 mg/l (ureaplasmas ... | 1987 | 3501335 |
| probable insensitivity of mollicutes to rifampin and characterization of spiroplasmal dna-dependent rna polymerase. | the effect of rifampin on five mollicutes (spiroplasma citri, spiroplasma melliferum, spiroplasma apis, acholeplasma laidlawii, and mycoplasma mycoides) was compared with that on escherichia coli. we found that, in contrast to wild-type e. coli, mollicutes were insensitive to rifampin. dna-dependent rna polymerases from s. melliferum and s. apis were purified to the stage where the enzymes were dependent on the addition of exogenous templates for activity. the enzymes were then tested for their ... | 1986 | 3519581 |
| interaction of polyene antibiotics with membrane lipids: physicochemical studies of the molecular basis of selectivity. | from various studies on the interaction of amphotericin b with unilamellar lipid vesicles, it appears that the strength of the binding does not depend only on the presence of sterol molecules in the membranes; and that several bound amphotericin b species are in competition, their relative amounts depending on the nature and percentage of sterol in the lipid bilayer. bound amphotericin b molecules exchange rapidly between the membranes. it is therefore possible to add the antibiotic by transfer ... | 1986 | 3527632 |
| [ribosomal genes--the only homologous dna segments in mycoplasmas]. | | 1986 | 3537771 |
| how do the polyene macrolide antibiotics affect the cellular membrane properties? | in the 1970's great strides were made in understanding the mechanism of action of amphotericin b and nystatin: the formation of transmembrane pores was clearly demonstrated in planar lipid monolayers, in multilamellar phospholipid vesicles and in acholeplasma laidlawii cells and the importance of the presence and of the nature of the membrane sterol was analyzed. for polyene antibiotics with shorter chains, a mechanism of membrane disruption was proposed. however, recently obtained data on unila ... | 1986 | 3539192 |
| membrane potential, lipid regulation and adenylate energy charge in acyl chain modified acholeplasma laidlawii. | in acholeplasma laidlawii variations induced in the transmembrane electrical potential have been shown to affect the membrane lipid composition. particularly the molar ratio between the predominant glucolipids, monoglucosyldiacylglycerol and diglucosyldiacylglycerol, decreases upon hyperpolarization and increases upon depolarization (clementz et al. (1986) biochemistry 25, 823-830). upon variation of the degree of membrane fatty acyl chain unsaturation, known to affect the passive permeability f ... | 1987 | 3567184 |
| activities of oxidative enzymes in mycoplasmas. | the activities of several oxidoreductases were measured in three fermentative and two nonfermentative mycoplasma species that were grown under aerobic or anaerobic conditions. acholeplasma laidlawii mg, mycoplasma hyorhinis gdl, and mycoplasma pneumoniae fh had very high apparent activities of pyruvate dehydrogenase and pyruvate dehydrogenase complex compared with the activities of mammalian fibroblasts or human platelet-enriched preparations, while mycoplasma salivarium vv and mycoplasma arthri ... | 1987 | 3571159 |
| mapping of mycoplasma virus dna replication origins and termini. | a pulse-labeling protocol has been used to study dna replication and map replication origins and termini in mycoplasma viruses l2 and l2ins1. the l2 genome is circular, double-stranded dna of 11.63 kilobase pairs (kb), and the 14.89-kb l2ins1 genome is l2 dna containing a 3.26-kb insertion. the data show that dna replication is bidirectional from two origins in l2 and three origins in l2ins1. the extra origin in l2ins1 arises from the fact that one of the l2 origins is in one of the sequences th ... | 1987 | 3573152 |
| cytotoxic and cytolytic activity of nonadecafluoro-n-decanoic acid on acholeplasma laidlawii. | we studied the interactions between the perfluorinated fatty acid nonadecafluoro-n-decanoic acid (ndfda) and the cell wall-less procaryote acholeplasma laidlawii, which were cultured in an identical medium base but with different serum supplements. when grown in mycoplasma media supplemented with pplo serum fraction (difco laboratories, detroit, mich.), a. laidlawii was rapidly killed by low concentrations of toxicant (less than 1.0 mm). at higher concentrations (greater than 10 mm), ndfda treat ... | 1987 | 3606106 |
| isolation of acholeplasmatales from rabbit faeces. | acholeplasma laidlawii was isolated from the faeces of 23.5% and 24% of groups of 51 conventional and 45 specified-pathogen-free (spf) rabbits respectively. isolation of the organism from individual animals could often be repeated, suggesting that infection was not merely transient. two further acholeplasmas were isolated from two spf rabbits. one was serologically related to acholeplasma modicum. the other could not be identified and may be a new species. | 1987 | 3626465 |
| the role of lipids in the interaction of acholeplasma laidlawii cells with lymphocytes. | the role of a. laidlawii membrane lipids in the organism's interaction with mouse spleen lymphocytes is analyzed. a. laidlawii cells were grown in a lipid-poor medium with unsaturated fatty acids that allowed cells with different degrees of membrane lipid microviscosity to be obtained. the intensity of the binding of a. laidlawii cells and derived liposomes with lymphocytes depended directly on the degree of fatty acid unsaturation. cholesterol incorporation into the a. laidlawii membrane reduce ... | 1987 | 3630470 |
| polymorphic regulation of membrane lipid composition. | | 1987 | 3657984 |
| isolation and characterization of a novel monoacylated glucopyranosyl neutral lipid from the plasma membrane of acholeplasma laidlawii b. | the level of a normally minor component of the membrane polar lipids of acholeplasma laidlawii b was significantly increased when the glucose supplement in the growth medium was reduced. under such glucose-limiting conditions the proportion of this component was found to be dependent upon the fatty acid supplement and could approach 55-60% of the total polar lipids when palmitic acid was used to supplement the growth medium. a number of physical measurements, along with specific chemical and enz ... | 1987 | 3663702 |
| calorimetric studies of the thermotropic phase behavior of cells, membranes and lipids from fatty acid-homogeneous acholeplasma laidlawii b. | we have investigated the comparative lipid thermotropic phase behavior of intact cells, isolated membranes and total membrane lipid dispersions from fatty acid-homogeneous acholeplasma laidlawii b by high-sensitivity differential scanning calorimetry. we find that the gel to liquid-crystalline phase transition temperature, enthalpy and degree of cooperativity are essentially identical in viable cells and isolated membranes and that these parameters are not affected by the thermal denaturation of ... | 1987 | 3667217 |
| extraction of proteins and membrane lipids during low temperature embedding of biological material for electron microscopy. | the extraction of proteins and membrane lipids from biological materials during embedding procedures for electron microscopy carried out at temperatures down to 223 k was studied. glutaraldehyde-fixed cells of acholeplasma laidlawii mainly served as test material. more than 99% of the protein and 88% of the lipid of these cells were retained after dehydration with ethanol or acetone between 277 and 223 k and infiltration with methacrylate at 223 k. when methanol was used for dehydration, only 54 ... | 1986 | 3712423 |
| ultrastructural changes in mollicutes induced by the peptide antibiotic herbicolin a. | electron microscopy of negatively stained mycoplasma, ureaplasma, and acholeplasma cells showed ultrastructural changes after 10 min of treatment of the organisms with the peptide antibiotic herbicolin a in concentrations ranging from 10 micrograms/ml for mycoplasma capricolum to 600 micrograms/ml for ureaplasma urealyticum. the morphological changes were shown to be reversible at low concentrations of the antibiotic but irreversible at high concentrations. | 1986 | 3717939 |
| cholesterol uptake capacity of acholeplasma laidlawii is affected by the composition and content of membrane glycolipids. | the composition of the cell membrane of 20 acholeplasma laidlawii strains grown under identical conditions was studied and correlated with the capacity of these strains to incorporate cholesterol. membranes of these strains had similar sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns and contained the same lipid species, but the relative amounts of the major polar lipids varied. statistical analyses revealed that the glycolipids, monoglucosyldiglyceride, and an unidentified gly ... | 1986 | 3729418 |
| isolation of mycoplasma virus l2 insertion variants and miniviruses. | we isolated two spontaneous variants of mycoplasma virus l2. both variants, designated l2ins1 and l2ins2, contained a 3.1-kilobase-pair (kbp) insertion in the 11.8-kbp wild-type l2 genome. the insert dna was shown to be derived from two noncontiguous regions of the l2 genome, and l2ins1 and l2ins2 differed only in the location of the 3.1-kbp insertion. we also isolated l2 miniviruses from serial passages of l2, l2ins1, and l2ins2 viruses. miniviruses contained circular dna molecules of 3.1 kbp o ... | 1986 | 3735491 |
| adsorption of mycoplasmavirus mv-l2 to acholeplasma laidlawii: effects of changes in the acyl-chain composition of membrane lipids. | the enveloped mycoplasmavirus mv-l2 and its host acholeplasma laidlawii ja1 were used to study the ways in which changes in the membrane lipid bilayer affect virus adsorption. the physical state of the membranes was altered by (i) using viruses and bacteria with different membrane lipid acyl-chain compositions, (ii) using incorporation of cholesterol, and (iii) changing the temperature. adsorption of viruses was strongly dependent on the acyl-chain composition of the virus and the host. adsorpti ... | 1986 | 3773051 |
| phase equilibria of membrane lipids from acholeplasma laidlawii: importance of a single lipid forming nonlamellar phases. | a basis for the reorganization of the bilayer structure in biological membranes is the different aggregate structures formed by lipids in water. the phase equilibria of all individual lipids and several in vivo polar lipid mixtures from acyl chain modified membranes of acholeplasma laidlawii were investigated with different nmr techniques. all dioleoyl (do) polar lipids, except monoglucosyldiglyceride (mgdg), form lamellar liquid crystalline (l alpha) phases only. the phase diagram of domgdg rev ... | 1986 | 3801429 |
| metabolic changes of membrane lipid composition in acholeplasma laidlawii by hydrocarbons, alcohols, and detergents: arguments for effects on lipid packing. | the packing of lipids into different aggregates, such as spheres, rods, or bilayers, is dependent on the hydrophobic volume, the hydrocarbon-water interfacial area, and the hydrocarbon chain length of the participating molecules, according to the self-assembly theory [israelachvili, j. n., marcelja, s., & horn, r. g. (1980) q. rev. biophys. 13, 121-200]. the origin of the participating molecules should be of no importance with respect to their abilities to affect the above-mentioned parameters. ... | 1986 | 3801430 |
| the effect of mycoplasmas and acholeplasmas of equine origin on organ cultures of chicken-embryo trachea. | chicken-embryo tracheal organ cultures were inoculated with equine strains of mycoplasma arginini, m. equigenitalium, 2 strains of m. subdolum, acholeplasma laidlawii and 3 strains of a. oculi. all strains established and multiplied in the explant cultures, but only m. subdolum and a. oculi produced a cytopathic effect on ciliated epithelial cells, causing sloughing of cells and cilia after 6 days. there was a correlation between ciliostasis and increase in titre of both m. subdolum and a. oculi ... | 1985 | 3837791 |
| polymeric phospholipids as new biomaterials. | phospholipid polymers form a new class of biomaterials with many potential applications in medicine and research. the development of these compounds is based upon the mimicry of cell surfaces and reflects our current understanding of the properties of membrane lipids. physicochemical characterization of the monomeric, diacetylenic phospholipids illustrates the similarities to naturally occurring lipids, similarities that are confirmed by the capacity to enrich the membranes of a. laidlawii to th ... | 1985 | 3860157 |
| fracturing of melamine-embedded cells and tissues: a new technique for studying cell membranes. | a new technique is presented for studying cell membranes by scanning electron microscopy. it is based on the observation that cells and tissues, embedded in a water-compatible melamine resin, are as hard as glass and consequently can be fractured with ease. fracture faces so exposed are either sputter-coated for studying the surface topography or re-embedded for thin-sectioning, or both. scanning electron microscopy shows that the fracture faces of a variety of tissues reveal cell membranes and ... | 1985 | 3871862 |
| elimination of mycoplasmas from cell cultures utilizing hyperimmune sera. | eighteen cell lines contaminated with various mycoplasmas have been treated with hyperimmune sera and mycoplasmas have been eradicated from all. after treatment the cell lines have been observed for a least one year and they are still free from mycoplasma contamination as ascertained by four independent mycoplasma detection assays. the hyperimmune sera used were of high titer, type-specific and growth-inhibiting. these sera were produced by immunization of rabbits with purified membranes from my ... | 1985 | 3902490 |
| acholeplasma laidlawii retains sensitivity to exogenous virus while releasing endogenous, mitomycin c induced, virus. brief report. | three of five acholeplasma laidlawii strains were found to carry mitomycin c inducible acholeplasmaviruses. these virus hosts were capable of propagating (1) virus homologous to the one it carried, and (2) exogenous virus while releasing induced endogenous virus. | 1985 | 3925928 |
| decontamination of cell lines by selective elimination of mycoplasmas. | | 1986 | 3964004 |
| [effect of acholeplasma laidlawii on the bacterial infection of white mice]. | | 1986 | 3964006 |
| transmembrane electrical potential affects the lipid composition of acholeplasma laidlawii. | in membranes of acholeplasma laidlawii, lipid composition is regulated as a function of several stimuli affecting the volume and length of the hydrocarbon chains and the hydrocarbon-water interfacial area. this regulation is vizualized as changes in the relative amounts of the major polar lipids monoglucosyl diglyceride and diglucosyl diglyceride. these lipids form reversed hexagonal and lamellar phases with water, respectively. however, mixtures of the two lipids, in the molar proportions found ... | 1986 | 3964647 |
| transfection of rep- mycoplasmas with viral single-stranded dna. | double-stranded dna from mycoplasma virus l2 can transfect acholeplasma laidlawii cells in the presence of polyethylene glycol (t. l. sladek and j. maniloff, j. bacteriol. 155:734-741, 1983). we report here that both single-stranded dna and double-stranded replicative form dna, from the single-stranded dna mycoplasma virus l51, are also infectious in this system. for both dnas transfection frequencies were in the range of 10(-8) transfectants per dna molecule and 10(-3) transfectants per cfu. an ... | 1985 | 3965744 |
| pyrimidine deoxyribonucleotide metabolism in acholeplasma laidlawii b-pg9. | extracts of acholeplasma laidlawii b-pg9 were examined for the enzymes associated with the interconversion of the pyrimidine deoxyribonucleotides and the biosynthesis of thymidine nucleotides. a. laidlawii b-pg9 possessed deaminases for deoxycytidine and dcmp, pyrophosphatases for dutp, phosphorylases for thymidine and uridine, and a membrane-associated pyrimidine deoxyribonucleoside monophosphate phosphatase activity. the role these enzyme activities have in the generation of deoxyribose-1-phos ... | 1985 | 3972768 |
| identification of lipoglycan antigens from the acholeplasma laidlawii cell membrane in crossed immunoelectrophoresis. | membranes from the wall-less prokaryote acholeplasma laidlawii contain a component termed lipoglycan or lipopolysaccharide (lps). the lipoglycan has extraction properties, which are similar to those of lps of gram-negative bacteria, but it is chemically distinct from bacterial lps. the membrane-bound lipoglycan of a. laidlawii did not seem to be particularly immunogenic and antibodies against it could not always be detected by rocket immunoelectrophoresis (rie) or crossed immunoelectrophoresis ( ... | 1985 | 3979563 |
| acylated proteins in acholeplasma laidlawii. | the covalent modification of membrane proteins by long-chain fatty acids was determined in two strains of acholeplasma laidlawii by one-dimensional gel electrophoresis of radiolabeled membranes. of the more than 50 membrane polypeptides detected, approximately 30 were labeled with [3h]palmitate, whereas covalent binding of [3h]oleate to membrane proteins could not be demonstrated. we suggest that in these wall-less bacteria, membrane protein acylation with saturated fatty acids may serve to ensu ... | 1985 | 3980443 |
| involvement of surface potential in regulation of polar membrane lipids in acholeplasma laidlawii. | upon induced variation of membrane lipid acyl chain unsaturation in acholeplasma laidlawii, the cells strongly change in a characteristic manner the proportions of individual (charged and noncharged) polar lipids synthesized. monolayer analysis of polar lipid extracts revealed different mean lateral molecular areas but similar surface charge densities. microelectrophoresis of these lipids indicated an almost constant lipid membrane zeta-potential of about -35 mv. simulation by the gouy-chapman-s ... | 1985 | 3980463 |
| 19f nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in acholeplasma laidlawii b membranes. orientational order in the presence of a series of positional isomers of cis-octadecenoic acid. | the 19f nuclear magnetic resonance (nmr) spectra of membranes of acholeplasma laidlawii b enriched with one of a series of positional isomers of cis-octadecenoic acid plus small amounts of one of a number of isomers of monofluoropalmitic acid were interpreted in terms of an orientational order parameter (smol). the variation of smol with the position of the fluorine label in the liquid-crystalline state yielded an "order profile" with characteristics similar to those obtained via 2h nmr and whic ... | 1985 | 3994965 |
| [acholeplasma laidlawii cell culture as an object for studying age-related changes in biological membranes]. | | 1985 | 3996198 |
| heterogeneous progeny viruses are produced by a budding enveloped phage. | infection of acholeplasma laidlawii cells by the temperate enveloped mycoplasma virus l2 results in production of three morphological forms of progeny l2 virus: l2-i, l2-ii, and l2-iii. these morphological forms can be separated by velocity sedimentation and agarose gel electrophoresis. the latter technique was used to size the quasi-spherical particles: l2-i is 74 nm, l2-ii is 88 nm, and l2-iii is 132 nm in diameter. the protein composition of the three l2 forms is the same, although there are ... | 1985 | 4008216 |
| fluorine-19 nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in acholeplasma laidlawii b membranes. gel-state disorder in the presence of methyl iso- and anteiso-branched-chain substituents. | the hydrocarbon chain orientational order parameters of membranes of acholeplasma laidlawii b enriched with large quantities of a linear saturated, a methyl iso-branched, or a methyl anteiso-branched fatty acid plus small quantities of various isomeric monofluoropalmitic acid probes were determined via fluorine-19 nuclear magnetic resonance spectroscopy (19f nmr) over a range of temperatures spanning the gel to liquid-crystalline phase transitions (determined by differential scanning calorimetry ... | 1985 | 4016065 |
| evidence for the bacterial origin of acholeplasma laidlawii a. | l-forms from a corynebacterium were induced in hyperosmolar media and gradually adapted to normal osmolarity over a period of two years. during this adaptation several morphologic l-form variants derived from the l-form cultures and were serologically identified as acholeplasma laidlawii a. the possibility that the bacterial and l-form cultures were contaminated with acholeplasmas was carefully investigated; this was determined not to be the case. membrane protein gel electrophoresis patterns of ... | 1985 | 4028662 |
| acholeplasma laidlawii cells acutely and chronically infected with group 1 acholeplasmavirus. | interactions between group 1 acholeplasmaviruses and their host cells were studied. acutely infected, chronically infected and uninfected cultures of acholeplasma laidlawii strain ja1 were compared by their growth in broth and on agar, by the sensitivities of the uninfected and chronically infected cells to representatives of each of the three groups of acholeplasmaviruses, and by their sds-page polypeptide profiles. acutely infected cells resembled uninfected cells by these criteria, except for ... | 1985 | 4045426 |
| infrared spectroscopic study of the gel to liquid-crystal phase transition in live acholeplasma laidlawii cells. | the temperature dependences of the infrared spectra of deuterium-labeled plasma membranes of live acholeplasma laidlawii b cells and of the isolated plasma membranes demonstrate that the profiles of the gel to liquid-crystal phase transitions are very different. at temperatures within the range of the phase transition, the live mycoplasma is able to keep the "fluidity" of its plasma membrane at a much higher value than that of the isolated plasma membrane at the same temperature. the difference ... | 1985 | 4052402 |
| prevalence of mycoplasma and acholeplasma species in cattle exhibiting various clinical diseases and pathological lesions in morocco. | | 1985 | 4060938 |
| fluorine-19 nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in acholeplasma laidlawii b membranes. a direct comparison of the effects of cis and trans cyclopropane ring and double-bond substituents on orientational order. | the hydrocarbon chain orientational order parameters of membranes of acholeplasma laidlawii b, enriched with large quantities of fatty acids containing either a cis or a trans cyclopropane ring or a cis or trans double bond, plus small quantities of one of an isomeric series of monofluoropalmitic acids, were determined via fluorine-19 nuclear magnetic resonance spectroscopy over a range of temperatures spanning the corresponding gel to liquid-crystalline phase transitions (determined via differe ... | 1985 | 4063347 |
| the photosensitizing activity of haematoporphyrin on mollicutes. | the photosensitizing activity of haematoporphyrin (hp) on mycoplasma hominis and acholeplasma laidlawii was studied as a function of the phase of growth and the amount of sterols in the cell membrane. less hp was bound to cells when the membrane had a high sterol content. both strains in the exponential but not in the stationary phase of growth were sensitive to hp treatment (above 1 microgram ml-1) in the dark. visible light irradiation of hp-loaded cells caused in all cases a decrease of cell ... | 1985 | 4067577 |
| selection and propagation of antibiotic-resistant mutants of acholeplasma by the addition of fresh culture medium containing antibiotics and protease to the medium cultured with acholeplasma. | | 1985 | 4087872 |
| [isolation of a mycoplasma strain similar to mycoplasma laidlawii from primary calf kidney cell culturs]. | | 1970 | 4101148 |
| mycoplasmatales virus-laidlawii 2, a new virus isolated from acholeplasma laidlawii. | | 1971 | 4106810 |
| glutamate dehydrogenase from mycoplasma laidlawii. | mycoplasma laidlawii possesses a single glutamate dehydrogenase (gdh) with dual coenzyme specificity [specificity for nicotinamide adenine dinucleotide (h) and nicotinamide adenine dinucleotide phosphate (h)]. a purification procedure is reported which results in an enzyme preparation with a specific activity of 79.5 units/mg and which displays only one significant protein band after gel electrophoresis. this one band was determined, by activity staining, to have all of the gdh nucleotide specif ... | 1972 | 4112954 |
| electron microscope observations on acholeplasma laidlawii viruses. | | 1972 | 4114278 |
| ultrastructure of mycoplasmatales virus laidlawii i. | | 1972 | 4116131 |
| silicotungstate negative staining of acholeplasma laidlawii membranes and lipids. | | 1972 | 4118305 |
| some differences between two viruses infecting acholeplasma laidlawii. | | 1973 | 4120326 |
| immunologically cross-reacting proteins in cell walls of many bacteria. | antibodies to a protein present in the cell envelope of hydrogenomonas facilis agglutinate many gram-negative bacteria and a few gram-positive bacteria. immunodiffusion studies of extracts from the various organisms tested indicate the presence of components sharing antigenic determinants with the cell envelope protein in all bacteria which can be agglutinated and a few that cannot. cross-reacting components were not detected in extracts of mycoplasma laidlawii, anacystis nidulans, and several e ... | 1973 | 4120606 |
| infection of acholeplasma laidlawii by mvl51 virus. | | 1973 | 4125688 |
| [electron microscopy studies of cell cultures: demonstration of a mixed infection by egtved virus of the rainbow trout and mycoplasma (acholeplasma laidlawii) (author's transl)]. | | 1973 | 4131319 |
| [morphology and ultrastructure of mycoplasma (acholeplasma) laidlawii cells]. | | 1973 | 4133913 |
| localization of the tween 20-soluble membrane proteins of acholeplasma laidlawii by crossed immunoelectrophoresis. | | 1974 | 4137837 |
| studies with lectins on the surface carbohydrate structures of mycoplasma membranes. | the surface carbohydrate structures on the cell membranes of various mycoplasma species have been investigated by using lectins, which are sugar-specific proteins. carbohydrate structures presumably bound to glycolipids, with both galactose and glucose units, were found to be exposed on the surface of mycoplasma pneumoniae and its temperature-sensitive mutants, m. mycoides var. mycoides and capri, m. pulmonis, m. gallinarum, and m. gallisepticum. lipid-bound glucose was found on m. neurolyticum. ... | 1974 | 4138526 |
| an electron-microscopic examination of certain bovine mycoplasmas stained with ruthenium red and the demonstration of a capsule on mycoplasma dispar. | | 1974 | 4139238 |
| use of the avidin-biotin complex for specific staining of biological membranes in electron microscopy. | to expand the electron microscopist's options in localization and visualization, a new and general staining technique has been tested. the avidin-biotin complex serves as a coupling between the electron-dense marker, ferritin, and points of interest in biological samples. when specific cellular components are tagged with biotin, those components may be visualized with ferritin-linked avidin. because of the remarkably strong affinity of avidin and biotin (characterized by an association constant ... | 1974 | 4139715 |
| [mycoplasma (acholeplasma laidlawii) from cold blood cell cultures]. | | 1972 | 4145171 |
| [influence of thallium acetate on the growth of acholeplasmataceae, mycoplasmataceae, and some bacteria species]. | | 1972 | 4145172 |