Showing papers on "Protoplast published in 1968"

Areas of Adhesion between Wall and Membrane of Escherichia coli

Abstract: SUMMARY: The envelope of Escherichia coli B exhibited areas at which cell wall and protoplasmic membrane were intimately associated. These areas became visible in ultrathin sections after the bacteria had been fixed and embedded in plasmolysed state. At numerous areas the protoplasmic membrane was observed to adhere to the wall, while the protoplast had shrunk. Duct-like extensions of the protoplasmic membrane were thus formed. Two hundred to 400 of these wall membrane associations are found per bacterium of E. coli B. In a number of cells the chromosomal material is seen in close proximity or connected to a wall membrane association.

Surface structure of yeast protoplasts.

Abstract: The fine structure of the yeast cell wall during protoplast formation was studied by means of phase-contrast microscopy and the freeze-etching technique The freeze-etching results indicated that at least in some cases the entire wall substance was not removed from the surface of the protoplasts After a treatment of 30 min to 3 hr with 2% snail enzymes, an innermost thin wall layer as well as remnants of the fibrillar middle layer sometimes could be demonstrated

Isolation, Composition, and Structure of Membrane of Listeria monocytogenes

Abstract: The plasma membrane of Listeria monocytogenes strain 42 was prepared by osmotic lysis of protoplasts with tris(hydroxymethyl)aminomethane (Tris) buffer, pH 8.2, containing MgCl2 and glucose, followed by washing with NaCl and MgCl2 in Tris buffer. Electron microscopy showed that the preparation was not contaminated with cytoplasmic material. The membrane preparation was composed of 55 to 60% protein, 1.5% ribonucleic acid, 0.1% deoxyribonucleic acid, 1.3 to 2.3% carbohydrate, 0.17 to 0.38% amino sugar, 0.2 to 0.4% rhamnose, 3.5 to 4.0% phosphorus, 10.5 to 12.0% nitrogen, and 30 to 35% lipid. Amino acid composition of the washed membrane showed some variation from that of the whole cells. Sulfur-containing amino acids were not present in the membrane hydrolysate. The membrane carbohydrate contained glucose, galactose, ribose, and arabinose. The membrane lipid was 80 to 85% phospholipid and 15 to 20% neutral lipid. The lipid contained 2.3 to 3.0% phosphorus, 2.5 to 3.0% carbohydrate, and a very small amount of nitrogen (0.2 to 0.3%). The phospholipid was of the phosphatidyl glycerol type. Electron micrographs of the washed membrane showed three layers. The outer and inner layers varied in thickness from 25 to 37 A and the middle layer from 20 to 25 A. The total thickness varied between 85 and 100 A. These preparations contained many vesicles which stained heavily with lead citrate. Some vesicles were also attached to the protoplast ghosts in the form of extrusions or intrusions, or both. Membrane preparations obtained by lysis of protoplasts in the absence of MgCl2 were fragmented and contained less lipid (20 to 22%) and ribonucleic acid (0.3 to 0.5%) than preparations prepared with MgCl2.

Structural and Immunological Studies on the Protoplast Membrane of the Yeast Candida utilis

Abstract: Cell membranes of the yeast Candida utilis isolated by lysis of protoplasts have been shown to be lipoprotein in nature Electron microscopy shows that Mg(++) is responsible for maintaining the integrity of the membrane A close serological relationship was found between membranes and cell walls isolated from the yeast This relationship was exhibited not only by membranes obtained by strepzyme treatment but also by those obtained from the action of helicase enzyme No such relationship existed between membranes and whole cells Related data have been obtained by treatment of yeasts with different digestive enzymes All of the results suggest that the protoplast membrane possesses traces of structural cell wall material This material is detectable by serological tests, but not by electron microscopy

Electron microscopy of the conidial protoplasts of Neurospova crassa

Abstract: Micromorphology of conidia resembles that of young hyphae except for the details of the cell wall structure, which is thicker and prominently developed in unhydrated conidia. Although mitochondria and endoplasmic reticulum are present in ungerminated conidia, these organelles increase greatly during germination, and vacuoles increase in size and number. Naked protoplasts protrude through a small pore in the partially digested wall of the conidium. Free protoplasts synthesize new wall material when incubated in a regenerative mixture. Similarities and differences between conidial germination and protoplast formation and regeneration are noted.