Crossword clues for viroid
Wiktionary
n. 1 plant pathogens, of the order ''Viroidales'', that consist of just a short section of RNA but without the protein coat typical of viruses 2 human pathogen, most notably hepatitis D.
WordNet
n. the smallest of viruses; a plant virus with its RNA arranged in a circular chromosome without a protein coat [syn: virusoid]
Wikipedia
Viroids are among the smallest infectious pathogens known, larger only than prions, which are misfolded proteins. Viroids consist solely of short strands of circular, single-stranded RNA without protein coats. They are mostly plant pathogens, some of which are of economic importance. Viroid genomes are extremely small in size, ranging from 246 to 467 nucleobases. In comparison, the genome of the smallest known viruses capable of causing an infection by themselves are around 2,000 nucleobases in size. The human pathogen hepatitis D virus is a defective RNA virus similar to viroids.
Viroids, the first known representatives of a new domain of "sub-viral pathogens", were discovered, initially characterized, and named by Theodor Otto Diener, plant pathologist at the U.S Department of Agriculture's Research Center in Beltsville, Maryland, in 1971. The first viroid to be identified was Potato spindle tuber viroid (PSTVd). Some 33 species have been identified.
Viroids do not code for any protein. Viroid's replication mechanism uses RNA polymerase II, a host cell enzyme normally associated with synthesis of messenger RNA from DNA, which instead catalyzes " rolling circle" synthesis of new RNA using the viroid's RNA as a template. Some viroids are ribozymes, having catalytic properties which allow self-cleavage and ligation of unit-size genomes from larger replication intermediates.
With Diener’s 1989 hypothesis that viroids may represent "living relics" from the widely assumed, ancient, and non-cellular RNA world—extant before the evolution of DNA or proteins—viroids have assumed significance beyond plant pathology to evolutionary science, by representing the most plausible RNAs capable of performing crucial steps in abiogenesis, the evolution of life from inanimate matter.
Usage examples of "viroid".
Locking her arms around the doctor despite his indignant yelp, she whirled him away from the entrance and beyond the snaking grasp of one of the viroid creatures.
Jadzia got so much radiation damage that she separated from Dax and sacrificed herself to lead the rest of the viroid aliens away.
He assumed that the apparatus had been infected with the viroids during its original assembly.
Specimens taken revealed the specificity of their action, much like that of the viroids already known.
It was a heretical, minority view, until the CDC in Atlanta decided out of desperation to try his theories out, and found the very dormant viroids Les predicted -- mixed in with the glue used to seal paper milk cartons, envelopes, postage stamps.
Viroids like this one caused several plant diseases, including pale cucumber disease, chrysanthemum stunt, chlorotic mottle, cadang-cadang, citrus exocortis.
The viroid was subsiding, eventually they could hardly even find it, no matter how hard and long they centrifuged samples.
And there were others helping in the search, working ahead of him on the frontiers, and beside him in related fields, from the small—virology, where the inquiries into tiny forms such as prions and viroids were revealing even smaller forms, almost too partial to be called life: virids, viris, virs, vis, vs, all of which might have relevance to the larger problem.
And there were others helping in the search, working ahead of him on the frontiers, and beside him in related fields, from the small-virology, where the inquiries into tiny forms such as prions and viroids were revealing even smaller forms, almost too partial to be called life: virids, viris, virs, vis, vs, all of which might have relevance to the larger problem.