Reston virus See Ebola virus

restriction endonuclease mapping A technique for relatively rapid comparison of DNA molecules based upon the size of fragments yielded in a standard reaction with a restriction endonuclease. The procedure may identify restriction sites and the sites of insertions or deletions in the DNA under test relative to a standard DNA of known sequence. A practical application is Pulse-Net, a system for analyzing the relationship between food-borne bacterial pathogens, by restriction fragment length polymorphism (RPLP).

restriction endonucleases Bacterial enzymes with a role in the host specificity of bacteriophages. They are highly specific, recognizing a particular sequence of nucleotides, where they attach and cut the nucleic acid chain. Thus they can inactivate foreign, incoming DNA. Host cell DNA is not cut because the specific sites have been methylated, and thus protected, by a methylase also present in the bacterial cell. In response to host cell restriction systems, some bacteriophages encode inhibitory proteins that can bind to and inactivate restriction endonucle-ases. Others, such as T-even phages, modify their own DNA by methylation corresponding to that occurring in certain bacterial hosts, so are not restricted.

Roberts RJ (1978) Nature 271, 502

restriction fragments Fragments of viral or cellular DNA produced by non-random cleavage of the DNA with specific endonucleases. The fragments of a particular DNA are characteristic. See restriction endonuclease mapping.

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