| 翻訳と辞書 |
Spiroplasma
''Spiroplasma'' is a genus of Mollicutes, a group of small bacteria without cell walls. ''Spiroplasma'' shares the simple metabolism, parasitic lifestyle, fried-egg colony morphology and small genome of other ''Mollicutes'', but has a distinctive helical morphology, unlike ''Mycoplasma''. It has a spiral shape and moves in a corkscrew motion. Most spiroplasmas are found either in the gut or haemolymph of insects, or in the phloem of plants. Spiroplasmas are fastidious organisms, which require a rich culture medium. There has been no success in culturing insect symbionts in vitro. Typically they grow well at 30 °C, but not at 37 °C. A few species, notably ''Spiroplasma mirum'', grow well at 37 °C (human body temperature), and cause cataracts and neurological damage in suckling mice. The best studied species of spiroplasmas are ''Spiroplasma citri'', the causative agent of Citrus Stubborn Disease, and ''Spiroplasma kunkelii'', the causative agent of Corn Stunt Disease.
==Human pathogenicity==
There is some disputed evidence for the role of spiroplasmas in the etiology of Transmissible Spongiform Encephalopathies (TSEs), due primarily to the work of Dr. Bastian, summarized below. Other researchers have failed to replicate this work, while the prion model for TSEs has gained very wide acceptance.〔Leach, R. H.; Mathews, W. B. & Will, R. (1983): Creutzfeldt-Jakob disease. "Failure to detect spiroplasmas by cultivation and serological tests. ''Journal of Neurological Science''59(3): 349-353. PMID 6348215 (HTML abstract)〕 Recent work appears to refute the role of spiroplasmas in the best small animal scrapie model (hamsters).〔Alexeeva, I.; Elliott, E. J.; Rollins, S.; Gasparich, G. E.; Lazar, J. & Rohwer, R. G. (2006): Absence of ''Spiroplasma'' or Other Bacterial 16S rRNA Genes in Brain Tissue of Hamsters with Scrapie. ''Journal of Clinical Microbiology'' 44(1): 91-97. PMID 16390954 (PDF fulltext )〕 Bastian et al. (2007) have responded to this challenge with the isolation of a spiroplasma species from scrapie-infected tissue, grown it in cell-free culture, and demonstrated its infectivity in ruminants.〔Bastian, F. O.; Sanders DE, Forbes, W.A.; Hagius, S.D.; Walker, J.V.; Henk, W.G.; Enright, F.M.& Elzer, P.H. (2007): ''Spiroplasma spp.'' from transmissible spongiform encephalopathy brains or ticks induce spongiform encephalopathy in ruminants. ''Journal of Medical Microbiology'' 56(9):1235-1252. PMID 17761489 〕
According to Frank O. Bastian, MD:
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Spiroplasma」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|