Biomaterial Database

Association of microcyst formation in Spirillum itersonii with the spontaneous induction of a defective bacteriophage. 1969

G D Clark-Walker

Mitomycin C and ultraviolet light were found to induce the formation of microcysts in Spirillum itersonii. These forms, as well as spontaneously occurring microcysts in this species, were found to contain phage tail parts, rhapidosomes, and a granular substance not seen in normal cells. It is suggested that microcysts are formed as the result of the induction of a defective phage. The production of phage lysozyme within the cell could lead to the formation of spherical forms as the cells lose their structural mucopeptide layer. Complete virus particles were not seen, nor was any biological activity demonstrated when the induced cultures were tested against two other strains of S. itersonii. The other strains of this bacterium also formed microcysts and phage tail parts when induced with mitomycin. Attempts to isolate an organism lacking the defective phage have been unsuccessful.

UI	MeSH Term	Description	Entries
D008242	Lysogeny	The phenomenon by which a temperate phage incorporates itself into the DNA of a bacterial host, establishing a kind of symbiotic relation between PROPHAGE and bacterium which results in the perpetuation of the prophage in all the descendants of the bacterium. Upon induction (VIRUS ACTIVATION) by various agents, such as ultraviolet radiation, the phage is released, which then becomes virulent and lyses the bacterium.	Integration, Prophage,Prophage Integration,Integrations, Prophage,Prophage Integrations
D008854	Microscopy, Electron	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.	Electron Microscopy
D008937	Mitomycins	A group of methylazirinopyrroloindolediones obtained from certain Streptomyces strains. They are very toxic antibiotics used as ANTINEOPLASTIC AGENTS in some solid tumors. PORFIROMYCIN and MITOMYCIN are the most useful members of the group.
D003673	Defective Viruses	Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat. Some are host-dependent defectives, meaning they can replicate only in cell systems which provide the particular genetic function which they lack. Others, called SATELLITE VIRUSES, are able to replicate only when their genetic defect is complemented by a helper virus.	Incomplete Viruses,Defective Hybrids,Defective Hybrid,Defective Virus,Hybrid, Defective,Hybrids, Defective,Incomplete Virus,Virus, Defective,Virus, Incomplete,Viruses, Defective,Viruses, Incomplete
D005827	Genetics, Microbial	A subdiscipline of genetics which deals with the genetic mechanisms and processes of microorganisms.	Microbial Genetics,Genetic, Microbial,Microbial Genetic
D001435	Bacteriophages	Viruses whose hosts are bacterial cells.	Phages,Bacteriophage,Phage
D013139	Spirillum	A genus of gram-negative, curved and spiral-shaped bacteria found in stagnant, freshwater environments. These organisms are motile by bipolar tufts of flagella having a long wavelength and about one helical turn. Some species of Spirillum cause a form of RAT-BITE FEVER.
D014466	Ultraviolet Rays	That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.	Actinic Rays,Black Light, Ultraviolet,UV Light,UV Radiation,Ultra-Violet Rays,Ultraviolet Light,Ultraviolet Radiation,Actinic Ray,Light, UV,Light, Ultraviolet,Radiation, UV,Radiation, Ultraviolet,Ray, Actinic,Ray, Ultra-Violet,Ray, Ultraviolet,Ultra Violet Rays,Ultra-Violet Ray,Ultraviolet Black Light,Ultraviolet Black Lights,Ultraviolet Radiations,Ultraviolet Ray