Cells, usually bacteria or yeast, which have partially lost their cell wall, lost their characteristic shape and become round.

The protoplasm and plasma membrane of plant, fungal, bacterial or archaeon cells without the CELL WALL.

Bacterial variants, unable to form a complete cell wall, which are formed in cultures by various bacteria; granules (L bodies) appear, unite, and grow into amorphous bodies which multiply and give rise to bacterial cells morphologically indistinguishable from the parent strain.

A basic enzyme that is present in saliva, tears, egg white, and many animal fluids. It functions as an antibacterial agent. The enzyme catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrin. EC 3.2.1.17.

RED BLOOD CELL sensitivity to change in OSMOTIC PRESSURE. When exposed to a hypotonic concentration of sodium in a solution, red cells take in more water, swell until the capacity of the cell membrane is exceeded, and burst.

The study of the origin, nature, properties, and actions of drugs and their effects on living organisms.

A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

A chelating agent that sequesters a variety of polyvalent cations such as CALCIUM. It is used in pharmaceutical manufacturing and as a food additive.

A genus of ascomycetous fungi of the family Saccharomycetaceae, order SACCHAROMYCETALES.

The outermost layer of a cell in most PLANTS; BACTERIA; FUNGI; and ALGAE. The cell wall is usually a rigid structure that lies external to the CELL MEMBRANE, and provides a protective barrier against physical or chemical agents.

Rupture of bacterial cells due to mechanical force, chemical action, or the lytic growth of BACTERIOPHAGES.

A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

A genus of gram-negative, aerobic bacteria that causes BRUCELLOSIS. Its cells are nonmotile coccobacilli and are animal parasites and pathogens. The bacterium is transmissible to humans through contact with infected dairy products or tissue.

Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.

Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.

Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. (Webster, 3d ed)

Viruses whose host is Escherichia coli.

Protein factors released from one species of YEAST that are selectively toxic to another species of yeast.

The chemical processes, enzymatic activities, and pathways of living things and related temporal, dimensional, qualitative, and quantitative concepts.

A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.

Viruses whose host is Salmonella. A frequently encountered Salmonella phage is BACTERIOPHAGE P22.

Change brought about to an organisms genetic composition by unidirectional transfer (TRANSFECTION; TRANSDUCTION, GENETIC; CONJUGATION, GENETIC, etc.) and incorporation of foreign DNA into prokaryotic or eukaryotic cells by recombination of part or all of that DNA into the cell's genome.

Diazonium compounds are organic derivatives containing the general formula R-N2+X-, where R represents an aryl or alkyl group, and X- is an anion such as bromide or chloride, formed by the reaction of amines with nitrous acid in an acidic medium.

A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.

Process of using a rotating machine to generate centrifugal force to separate substances of different densities, remove moisture, or simulate gravitational effects. It employs a large motor-driven apparatus with a long arm, at the end of which human and animal subjects, biological specimens, or equipment can be revolved and rotated at various speeds to study gravitational effects. (From Websters, 10th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria that occurs in the intestines of humans and a wide variety of animals, as well as in manure, soil, and polluted waters. Its species are pathogenic, causing urinary tract infections and are also considered secondary invaders, causing septic lesions at other sites of the body.

Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.

Proteins found in any species of bacterium.

A group of simple proteins that yield basic amino acids on hydrolysis and that occur combined with nucleic acid in the sperm of fish. Protamines contain very few kinds of amino acids. Protamine sulfate combines with heparin to form a stable inactive complex; it is used to neutralize the anticoagulant action of heparin in the treatment of heparin overdose. (From Merck Index, 11th ed; Martindale, The Extra Pharmacopoeia, 30th ed, p692)

A 25-kDa peptidase produced by Staphylococcus simulans which cleaves a glycine-glcyine bond unique to an inter-peptide cross-bridge of the STAPHYLOCOCCUS AUREUS cell wall. EC 3.4.24.75.

A genus of gram-positive, anaerobic bacteria whose organisms divide in three perpendicular planes and occur in packets of eight or more cells. It has been isolated from soil, grains, and clinical specimens.

A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter.

Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Viruses whose nucleic acid is DNA.

Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.