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On-Line Glossary: N

Each entry consists of a term (in bold), a definition of the term, and a number in parentheses (0) indicating the source of the definition. Clicking on the speaker icon will give you the pronunciation of the term. (Be sure to close the window for the sound player after each use.) The pencil icon will give you a drawing, and the camera icon will give you a photograph.


necrosis. Localized death of cells or tissues. (3)

necrotic. Dead. (8)

necrotroph. 1. An organism that kills part or all of another organism before deriving nutrients from it (usually applied to plant pathogens). 2. An organism that derives nutrients from dead plant or animal tissues, whether or not it is responsible for the death of those tissues. (16)

nematicide. A chemical compound or physical agent that kills nematodes. (2)

nematode. More or less elongate, spindle-shaped, worm-like animals ranging in size from less than a millimeter to several meters in length, living as saprophytes in soil or water or as parasites of plants or animals. (3)

neotype. A specimen selected as the type subsequent to the original description in cases in which the primary types are definitely known to have been destroyed. (14)

nepovirus. (Siglum of nematode polyhedral virus). Member of a group of multicomponent plant viruses with two isometric particles containing two species of linear RNA, transmitted mechanically and by soil-inhabiting nematodes. (5)

nerve ring. The center of the nervous system of nematodes that encircles the esophagus; composed largely of nerve fibers and associated ganglia. (14)

nomenclature. A system of names, or naming, as applied to the subjects or study in any art or science, especially in botany and zoology. (17)

noncirculative transmission. Virus transmission characterized by a very short period of acquisition of the virus by a vector (e.g., an aphid), no latent period before the vector can transmit the virus, and a short period of retention by the vector after acquisition. (Also termed nonpresistent transmission.) (5)

nonseptate. Lacking cross-walls. (4)

Northern blot. An RNA blot. This term originated as lab jargon; not a generally accepted term. (19)

nuclease. Any enzyme that can cleave the sugar-phosphate backbone of a nucleic acid. (16)

nucleoprotein. A compound of nucleic acid and protein. (20)

nutrient broth. A liquid basal medium. (16)

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