Determination of the topography and biometry of chlorosomes by atomic force microscopy

被引:0
作者
Asunción Martinez-Planells
Juan B. Arellano
Carles M. Borrego
Carmen López-Iglesias
Frederic Gich
Jesús Garcia-Gil
机构
[1] University of Girona,Section of Microbiology. Institute of Aquatic Ecology
[2] Campus de Montilivi,Plant Physiology Department
[3] Institute of Natural Resources and Agrobiology,Scientific and Technical Services
[4] (CSIC),undefined
[5] University of Barcelona,undefined
来源
Photosynthesis Research | 2002年 / 71卷
关键词
atomic force microscopy; biometry; chlorosomes; freeze-drying; green sulfur bacteria; topography; transmission electron microscopy;
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学科分类号
摘要
Isolated chlorosomes of several species of filamentous anoxygenic phototrophic bacteria (FAPB) and green sulfur bacteria (GSB) were examined by atomic force microscopy (AFM) to characterize their topography and biometry. Chlorosomes of Chloroflexusaurantiacus, Chloronema sp., and Chlorobium (Chl.) tepidum exhibited a smooth surface, whereas those of Chl. phaeobacteroides and Chl. vibrioforme showed a rough one. The potential artifactual nature of the two types of surfaces, which may have arisen because of sample manipulation or AFM processing, was ruled out when AFM images and transmission electron micrographs were compared. The difference in surface texture might be associated with the specific lipid and polypeptide composition of the chlorosomal envelope. The study of three-dimensional AFM images also provides information about the size and shape of individual chlorosomes. Chlorosomal volumes ranged from ca. 35 000 nm3 to 247 000 nm3 for Chl. vibrioforme and Chl. phaeobacteroides, respectively. The mean height was about 25 nm for all the species studied, except Chl. vibrioforme, which showed a height of only 14 nm, suggesting that GSB have 1–2 layers of bacteriochlorophyll (BChl) rods and GFB have ∼4. Moreover, the average number of BChl molecules per chlorosome was estimated according to models of BChl rod organisation. These calculations yielded upper limits ranging from 34 000 BChl molecules in Chl. vibrioforme to 240 000 in Chl. phaeobacteroides, values that greatly surpass those conventionally accepted.
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页码:83 / 90
页数:7
相关论文
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