The antigens responsible for the production of antibodies to Mycoplasma laidlawii and M. gallisepticum causing growth and metabolic inhibition of these organisms were localized in the cell membrane. Various membrane fractions were tested for serological activity. Membrane lipids were completely or almost completely inactive, whereas several preparations of defatted membrane proteins retained some serological activity, shown by their ability to stimulate metabolic inhibition antibody in rabbits and to adsorb metabolic inhibition antibody and form precipitation lines with an antiserum to the membrane. When the membranes were heated to 65 C for 1 hr, they virtually lost their ability to adsorb metabolic inhibition antibody, which suggests that the antigenic determinants are proteins. Serological activity was retained in reaggregated membranes obtained by dialysis against Mg(2+) of membranes solubilized in sodium dodecyl sulfate. The amount of solubilized membrane protein and lipid incorporated into the reaggregated membranes could be regulated by varying the Mg(2+) concentration. As the serological tests indicated that the various membrane antigens were selectively incorporated into the different reaggregated membranes, the use of controlled reaggregation of solubilized membranes is suggested as a new tool for the fractionation and antigenic analysis of membrane proteins.

Adsorption↗

PubMed1968

Effect of substrate salinity on the ability for protein synthesis in pea roots.

THE EFFECT OF SALINITY ON INCORPORATION OF AMINO ACIDS INTO ROOT TIP PROTEIN IS APPARENTLY OF DUAL NATURE: in presence of salts the uptake is depressed and the normal metabolic pathways are disturbed. If the roots were grown at high salt concentration, uptake and incorporation are affected even if they are carried out in the absence of salt. NaCl and Na(2)SO(4) affect uptake, incorporation, and metabolism of (14)C leucine in different ways. There are also preliminary indications that in pea roots grown at different types of salinity, different proteins may be synthesized. Kinetin was found to inhibit incorporation of amino acids into non stressed and Na(2)SO(4) stressed roots, but promotes uptake and incorporation of amino acids into protein in NaCl stressed tissue. It seems that there are some pronounced differences between the effects of NaCl and Na(2)SO(4) salinities on the metabolism of pea root tissue.

Journal Article↗

PubMedDate not supplied

The adhesins of Mycoplasma gallisepticum and M. pneumoniae.

The growth of M. gallisepticum was monitored in regard to their capacity to haemagglutinate. The maximal potential was with cells grown for about 22 h. M. gallisepticum, like M. pneumoniae, possess a Triton shell intracellular filamentous structure which is revealed by exposing the cells to a relatively low concentration of Triton-X100. The adhesin of M. gallisepticum was partially purified on sialoglycopeptide conjugated to Sepharose-4B. The adhesin fraction was primarily composed of one polypeptide of about 75,000 molecular weight.

Adhesins, Bacterial↗

PubMedDate not supplied

Attachment of mycoplasmas to host cell membranes.

Pathogenic mycoplasmas rarely invade the tissues or bloodstream. Their adherence to epithelial cell surface, the first stage in disease, involves protein binding sites on the mycoplasmal cell membrane and receptors on the host cell membrane. Strong evidence indicates that Mycoplasma gallisepticum and Mycoplasma pneumoniae adhere with the aid of sialic acid residues on host cells, but the data do not preclude participation by other host-cell membrane components. Several studies indicate that these mycoplasmas adhere by blebs or terminal structures; others suggest that binding occurs via other cell areas. Scanning electron microscopy suggests tight interaction between these mycoplasmas and red blood cell membranes, causing imprints resembling those from interaction of viruses with red blood cells. Because sialoglycoproteins are major sites for attachment of M. pneumoniae to respiratory epithelium and red blood cells, glycophorin--the major sialoglycoprotein of human red blood cells--was the ligand used in affinity chromatography for isolation of the binding sites specific for sialic acid receptors from M. pneumoniae membranes solubilized by detergents. The fraction eluted with 0.2% sodium dodecylsulfate from the glycophorin-Sepharose column, highly enriched with two proteins, exhibited high binding capacity to glycophorin-Sepharose beads and lower binding capacity to human red blood cells. The latter capacity was nearly abolished by glycophorin, but not by its hydrophobic moiety.

Adhesiveness↗

PubMedDate not supplied

Dual energy metabolism-dependent effect of Ureaplasma urealyticum infection on sperm activity.

Genital Ureaplasma urealyticum infection is considered a sexually transmitted infection. It has long been debated whether the presence of U. urealyticum in semen may be a possible cause of infertility. Long-term incubation (4 hours or overnight) of sperm cells with U. urealyticum in vitro resulted in a significant inhibition of sperm motility and membrane alteration whereas a short incubation (45 minutes) of sperm cells with ureaplasmas resulted in an acceleration of sperm velocity. The aim of this study was to understand these contradictory reports of U. urealyticum infection on sperm motility. Spermatozoa from fresh ejaculates of normozoospermic semen of men who were referred to the university Male Fertility Laboratory for semen analysis, with no history of genital tract infection, and from normal Assaf breed rams were infected in vitro with U. urealyticum serotype 8, at different pHs and O2 concentrations. Sperm viability and motility and changes in extracellular pH were evaluated. A significant (16%-43%) increase in sperm activity was observed upon infection at alkaline pH (7.8) under aerobic or hypoxic conditions, and a 58% increase was observed under anaerobic conditions and pH 7.2. When the infection was conducted under aerobic conditions and acidic pH (6.3), or under hypoxic conditions at neutral pH (7.2), an 8%-25% inhibition of sperm activity was observed. These results indicate that when sperm activity depends on mitochondrial oxidative phosphorylation, usually at low pHs, U. urealyticum competes with mitochondrial energy production and therefore reduces sperm motility and viability. However, when sperm energy metabolism depends on glycolysis, usually at higher pHs, U. urealyticum stimulates glycolysis and sperm activity.

Anaerobiosis↗

PubMedDate not supplied

Mycoplasma attachment to solid surfaces: a review.

Mycoplasma attachment to glass in a protein-containing environment requires energization of the cells, probably to provide more accessibility of binding sites. The substance mediating attachment is of protein nature. Studies with monoclonal antibodies on M. pneumoniae suggest a concentration of the binding sites at the tip structure.

Adhesiveness↗

PubMedDate not supplied

Purification of attachment moiety: a review.

Mycoplasma pneumoniae and M. gallisepticum possess binding sites of protein nature which mediate attachment to neuraminidase-sensitive regions on both respiratory epithelium and red blood cells. The binding sites of these organisms are similar though not identical. Several approaches were applied for the isolation of the binding sites. Of these, the use of affinity chromatography yield the least complex protein fraction. We have recently been using sialoglycopeptides as the ligands in affinity chromatography. The availability of monoclonal antibodies which inhibit the attachment of M. pneumoniae to host cells should provide a very specific tool for the isolation of the attachment moiety. It should be mentioned that not all mycoplasmas adhere to host cells via sialic acid specific receptors, and other approaches should be developed to study these mycoplasmas' attachment moieties.

Adhesiveness↗