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A novel cyanobacterium exhibiting an elevated tolerance for iron (2005)

Brown, Igor I. ; Mummey, Daniel ; Cooksey, Keith E.

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology ecology 52 (2005), S. 0

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ISSN: 1574-6941

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Studies directed at cyanobacteria inhabiting iron-depositing hot springs may provide insights into the role of both ancient and contemporary cyanobacteria mediated iron transformations. Here we phylogenetically, morphologically and physiologically characterize a novel cyanobacterium isolated from an iron-depositing hot spring. Phylogenetic analyses indicate that the bacterium is a representative of a new genus, exhibiting a maximum 95.2% homology to database sequences. The isolate is a unicellular cyanobacterium with bladder-like cells typically packed as duplexes, or in extracellular polymeric substance covered clumps and small chains without the ability to produce baeocystes. No growth without added combined nitrogen occurred. While requiring relatively large amounts of iron for growth (〉40μM), the isolate was shown to facilitate removal of iron from culture media. These results suggest that the isolate may be an important component of an iron-depositing microbial community. The name “Chroogloeocystis siderophila” for this cyanobacterium is proposed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1016/j.femsec.2004.11.020

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An investigation of the involvement of cytoskeletal structures and secretion in gliding motility of the marine diatom, Amphora coffeaeformis (1985)

Webster, Daniel R. ; Cooksey, Keith E. ; Rubin, Robert W.

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 5 (1985), S. 103-122

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ISSN: 0886-1544

Keywords: gliding ; cell motility ; cytoskeleton ; diatoms ; capping ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Gliding motility was investigated in the marine diatom, Amphora coffeaeformis. Ultrastructural, biochemical, and pharmacological protocols were employed to probe the possible involvement of cytoskeletal proteins and a secretory process in gliding motility. Motility rate was measured using a video recording apparatus, and the effects of various cytoskeleton-disrupting drugs on motility were tested. Cytochalasins D and E, podophyllotoxin, and vinblastine (all at 25 μUg/ml) reversibly inhibited motility, as did monensin (10 μUM) and pronase (25 μUg/ml). Biochemical protein analysis of whole-cell extracts by one- and two-dimensional polyacrylamide gel electrophoresis revealed polypeptides comigrating with rabbit skeletal muscle actin and bovine brain tubulin; however, specific assays used to separate actin from whole-cell preparations gave ambiguous results. Ultrastructural studies revealed the presence of extracellular material between the raphe canal and the substratum in motile cultures. An assay was devised for the detection of radioactively labeled material (MW 〉 1800 Daltons) released by motile cultures into the culture medium. When cultures were treated with either an anticytoskeletal drug or monensin, motility was inhibited while the amount of measured radioactivity increased over solvent-treated control groups. The results from this study indicate possible roles for both actin- and tubulin-based structures in gliding motility of Amphora. Though secretion may be necessary for gliding to occur, its exact relationship to motility was not deduced. The data obtained in this study are compatible with a theory for the mechanism of gliding which involves the surface translocation of externally exposed membrane proteins against an immobile matrix of substratum-attached secreted material to generate the force required for movement.

Additional Material: 8 Ill.