納米細(xì)菌是一種形似細(xì)胞的微小顆粒,，直徑可小至80納米,，只能通過電子顯微鏡觀察，且廣泛存在于各種生物體和非生物體中,。人們一直懷疑它是生物,，原因是：納米細(xì)菌往往形似正在分裂的細(xì)胞；而且其周圍可聚集羥磷灰石———動物骨骼中的主要成分,，這被認(rèn)為是納米細(xì)菌繁殖的可能方式,。那么，納米細(xì)菌是活的嗎,？屬不屬于生物范疇,？中國臺灣成功大學(xué)和美國洛克菲勒大學(xué)的科學(xué)家在《美國國家科學(xué)院院刊》上發(fā)表論文稱，基于DNA繁殖模式的生物最小直徑要在200納米以上,，所以納米細(xì)菌并非生物,。
研究人員通過一系列實(shí)驗(yàn)發(fā)現(xiàn)：健康人類血清中的納米細(xì)菌以復(fù)合碳酸鈣為成分，不包含DNA或RNA的痕跡,，應(yīng)該不是以生物方式生成的,。之前研究也有類似看法，但沒有給出納米細(xì)菌的化學(xué)構(gòu)成。此次則提出了一個納米細(xì)菌生長的化學(xué)模型,，根據(jù)這一假說,，人們能通過改變碳酸鈣沉淀所需的基質(zhì)，去控制納米細(xì)菌生長的速度和形狀,。
科學(xué)家還發(fā)現(xiàn),，羥磷灰石只在特定狀態(tài)下，比如與抑制晶體生長蛋白質(zhì)混合時,，才聚集在納米細(xì)菌周圍,，說明羥磷灰石并非納米細(xì)菌生長所必需。
研究人員之一,，洛克菲勒大學(xué)的約翰?揚(yáng)說：“納米細(xì)菌曾有望成為地球上最小的細(xì)胞形式,，并解釋地球和地外細(xì)胞生命的起源。但我們的成果明確否認(rèn)了納米細(xì)菌是活的有機(jī)體,。”之前的有關(guān)研究曾暗示,，納米細(xì)菌是引起腎病和動脈硬化癥等許多疾病的病原體。約翰?揚(yáng)并未否定這種可能性,，但他認(rèn)為尚缺乏充分證據(jù),。
生物谷推薦原始出處：
PNAS 2008 105: 5549-5554; published online on April 2, 2008, 10.1073/pnas.0711744105
Purported nanobacteria in human blood as calcium carbonate nanoparticles
Jan Martel*, and John Ding-E Young
*Department of Biochemistry and Cellular Molecular Biology, Chang Gung University, 259 Wen-Hua First Road, Kwei-Shan, Tao-Yuan 333, Taiwan, Republic of China; and Department of Cellular Physiology and Immunology, The Rockefeller University, New York, NY 10021
Edited by Norman R. Pace, University of Colorado, Boulder, CO, and approved February 29, 2008 (received for review December 13, 2007)
Recent evidence suggests a role for nanobacteria in a growing number of human diseases, including renal stone formation, cardiovascular diseases, and cancer. This large body of research studies promotes the view that nanobacteria are not only alive but that they are associated with disease pathogenesis. However, it is still unclear whether they represent novel life forms, overlooked nanometer-size bacteria, or some other primitive self-replicating microorganisms. Here, we report that CaCO3 precipitates prepared in vitro are remarkably similar to purported nanobacteria in terms of their uniformly sized, membrane-delineated vesicular shapes, with cellular division-like formations and aggregations in the form of colonies. The gradual appearance of nanobacteria-like particles in incubated human serum as well as the changes seen with their size and shape can be influenced and explained by introducing varying levels of CO2 and NaHCO3 as well as other conditions known to influence the precipitation of CaCO3. Western blotting reveals that the monoclonal antibodies, claimed to be specific for nanobacteria, react in fact with serum albumin. Furthermore, nanobacteria-like particles obtained from human blood are able to withstand high doses of -irradiation up to 30 kGy, and no bacterial DNA is found by performing broad-range PCR amplifications. Collectively, our results provide a more plausible abiotic explanation for the unusual properties of purported nanobacteria.
