Abstract：
:The 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.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Brown RM Jr,Kudlicka K,Cousins SK,Nagy Rsubject
Has Abstractpub_date
1992-11-01 00:00:00pages
1247-58issue
11eissn
0002-9122issn
1537-2197journal_volume
79pub_type
杂志文章abstract：PREMISE OF THE STUDY:Over one-third of the native flowering plant species in the Hawaiian Islands are listed as federally threatened or endangered. Lack of sufficient pollination could contribute to reductions in populations, reproduction, and genetic diversity among these species but has been little studied. METHODS:...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1233
更新日期：2019-02-01 00:00:00
abstract：:Restriction fragment length polymorphism (RFLP) analysis of chloroplast (cp) DNA is a powerful tool for the study of microevolutionary processes in land plants, yet has not previously been applied to seaweed populations. We used cpDNA-RFLP, detected on Southern blots using labeled total plastid DNA, to search for intr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-07-01 00:00:00
abstract：:The Strait of Gibraltar is the most important barrier disconnecting the landmasses of Europe and Africa on the western Mediterranean extreme. Carex helodes is a wind-pollinated species endemic to the western Mediterranean. Because molecular and cytogenetic data allow the inference of its evolutionary history, we analy...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.2007342
更新日期：2008-06-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.10.1624
更新日期：2002-10-01 00:00:00
abstract：PREMISE OF THE STUDY:Evolutionary and biogeographic history, including past environmental change and diversification processes, are likely to have influenced the expansion, migration, and extinction of populations, creating evolutionary legacy effects that influence regional species pools and the composition of communi...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1049
更新日期：2018-03-01 00:00:00
abstract：PREMISE OF THE STUDY:Uplift of the tropical Andes had a significant impact on the diversification of South American flora and fauna. Recent biogeographic inquiries have established patterns of Andean divergence, but investigations on ferns are scant. The fern genus Polystichum Roth (Dryopteridaceae) combines widespread...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1300191
更新日期：2014-02-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1400486
更新日期：2015-03-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1100040
更新日期：2011-07-01 00:00:00
abstract：:In volume 97(2) of the American Journal of Botany (pp. 268-275), we published an article entitled "Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats". Here, we respond to a letter and a commentary on our article in the pres...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000172
更新日期：2010-07-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.91.6.850
更新日期：2004-06-01 00:00:00
abstract：UNLABELLED: PREMISE OF THE STUDY:Large-scale population genetics studies are required to investigate the dispersal processes underlying the emergence of Mycosphaerella fijiensis, a fungal pathogen of banana. To this end, we have developed an optimized genotyping procedure combining novel microsatellite markers and a m...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000295
更新日期：2010-12-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0900394
更新日期：2010-03-01 00:00:00
abstract：PREMISE OF STUDY:Sequence analyses for Pinaceae have suggested that extant genera diverged in the late Mesozoic. While the fossil record indicates that Pinaceae was highly diverse during the Cretaceous, there are few records of living genera. This description of an anatomically preserved seed cone extends the fossil re...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1100568
更新日期：2012-06-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0700006
更新日期：2008-07-01 00:00:00
abstract：:Species of Collinsia and Tonella, the two sister genera of self-compatible annuals that constitute tribe Collinsieae, show extensive variation in floral size and morphology and in patterns of stamen and style elongation during the life of the flower (anthesis). We used a nuclear ribosomal ITS phylogeny, independent co...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.1.37
更新日期：2002-01-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200076
更新日期：2012-09-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200180
更新日期：2012-12-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1500108
更新日期：2016-01-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.93.2.197
更新日期：2006-02-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.92.9.1425
更新日期：2005-09-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000226
更新日期：2011-05-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-04-01 00:00:00
abstract：:Seed and pollen morphology were studied by light microscopy and scanning electron microscopy in 39 North and Central American species of Houstonia (including Hedyotis, but excluding Oldenlandia). Chromosome counts were obtained for eight taxa, of which five lacked previous chromosome data. A chromosome number of n = 1...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/j.1537-2197.1986.tb09686.x
更新日期：1986-01-01 00:00:00
abstract：:In rainforests, trunk size, strength, crown position, and geometry of a tree affect light interception and the likelihood of mechanical failure. Allometric relationships of tree diameter, wood density, and crown architecture vs. height are described for a diverse range of rainforest trees in Brunei, northern Borneo. T...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.94.12.1951
更新日期：2007-12-01 00:00:00
abstract：PREMISE OF THE STUDY:A total of 38 polymorphic microsatellite loci of the Indian jujube (Ziziphus mauritiana), an economically important fruit tree, were developed to evaluate genetic diversity and aid in the identification of cultivars. METHODS AND RESULTS:The 38 microsatellite markers were isolated from the Indian j...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1100500
更新日期：2012-05-01 00:00:00
abstract：:We investigated the hypothesis that dandelion clones (Taraxacum officinale Weber, sensu lato; Asteraceae) differ in their floral stage timing characteristics under a constant set of environmental conditions. To test this hypothesis, plants representing nine different dandelion clones (identified by DNA fingerprinting)...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.91.11.1828
更新日期：2004-11-01 00:00:00
abstract：:A long-term survey (1990-2000) of pollination modes of 86 tree species was carried out at Kakachi, a mid-elevation wet forest site in southern Western Ghats, India. Observations were made on 86 tree species. This comprises 80% of the total arborescent species present in the site. Approximately 75% of these species wer...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.90.4.650
更新日期：2003-04-01 00:00:00
abstract：PREMISE OF THE STUDY:Phylogenetic and morphological studies have helped clarify the systematics of large and complex groups such as the tribe Crotoneae (Euphorbiaceae). However, very little is known about the diversity, structure, and function of anatomical features in this tribe. Crotoneae comprises the species-rich p...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1500017
更新日期：2015-06-01 00:00:00
abstract：PREMISE OF THE STUDY:Microsatellite primers were developed in the native legume tree Anadenanthera colubrina var. cebil to study the genetic diversity and genetic structure in natural populations in Argentina. METHODS AND RESULTS:Nine microsatellite markers were identified using a genomic library enriched for tandemly...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200078
更新日期：2012-09-01 00:00:00
abstract：:The genus Rosa has a complex evolutionary history caused by several factors, often in conjunction: extensive hybridization, recent radiation, incomplete lineage sorting, and multiple events of polyploidy. We examined the applicability of AFLP markers for reconstructing (species) relationships in Rosa, using UPGMA clus...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.95.3.353
更新日期：2008-03-01 00:00:00
