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Gravity effects on cellulose assemblyThe effect of microgravity on cellulose synthesis using the model system of Acetobacter xylinum was the subject of recent investigations using The National Aeronautics and Space Administration's Reduced Gravity Laboratory, a modified KC-135 aircraft designed to produce 20 sec of microgravity during the top of a parabolic dive. Approximately 40 parabolas were executed per mission, and a period of 2 x g was integral to the pullout phase of each parabola. Cellulose biosynthesis was initiated on agar surfaces, liquid growth medium, and buffered glucose during parabolic flight and terminated with 2.0% sodium azide or 50.0% ethanol. While careful ground and in-flight controls indicated normal, compact ribbons of microbial cellulose, data from five different flights consistently showed that during progression into the parabola regime, the cellulose ribbons became splayed. This observation suggests that some element of the parabola (the 20 sec microgravity phase, the 20 sec 2 x g phase, or a combination of both) was responsible for this effect. Presumably the cellulose I alpha crystalline polymorph normally is produced under strain, and the microgravity/hypergravity combination may relieve this stress to produce splayed ribbons. An in-flight video microscopy analysis of bacterial motions during a parabolic series demonstrated that the bacteria continue to synthesize cellulose during all phases of the parabolic series. Thus, the splaying may be a reflection of a more subtle alteration such as reduction of intermicrofibrillar hydrogen bonding. Long-term microgravity exposures during spaceflight will be necessary to fully understand the cellulose alterations from the short-term microgravity experiments.
Document ID
20040120593
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Brown, R. M. Jr
(The University of Texas at Austin 78713-7640, United States)
Kudlicka, K.
Cousins, S. K.
Nagy, R.
Brown RM, J. r.
Date Acquired
August 22, 2013
Publication Date
November 1, 1992
Publication Information
Publication: American journal of botany
Volume: 79
Issue: 11
ISSN: 0002-9122
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG9-397
Distribution Limits
Public
Copyright
Other
Keywords
manned
NASA Discipline Plant Biology
Flight Experiment
short duration
Parabolic Flight
Non-NASA Center

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