Molecular cloning and nucleotide sequence of a gene encoding a cotton palmitoyl-acyl carrier protein thioesterase.
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A cotton genomic clone containing a 17.4-kb DNA segment was found to encompass a palmitoyl-acyl carrier protein (ACP) thioesterase (Fat B1) gene. The gene spans 3.6 kb with six exons and five introns, and is apparently the first plant FatB acyl-ACP thioesterase gene to be completely sequenced. The six exons are identical in nucleotide sequence to the open reading frame of the corresponding cDNA, and would encode a preprotein of 413 amino acids. The preprotein can clearly be identified as a FatB acyl-ACP thioesterase from its similarity to the deduced amino acid sequences of other FatB thioesterase preproteins. A 5'-flanking region of 914 bp was sequenced, with the potential TATA basal promoter 324 bp upstream from the ATG initiation codon. The 5'-flanking sequence also has a putative CAAT box and two presumptive basic region helixloop-helix (bHLH) elements with the consensus motif CANNTG (termed an E box), implicated as being a positive regulatory element in seed-specific gene expression. (+info)
Duplicated genes evolve independently after polyploid formation in cotton.
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Of the many processes that generate gene duplications, polyploidy is unique in that entire genomes are duplicated. This process has been important in the evolution of many eukaryotic groups, and it occurs with high frequency in plants. Recent evidence suggests that polyploidization may be accompanied by rapid genomic changes, but the evolutionary fate of discrete loci recently doubled by polyploidy (homoeologues) has not been studied. Here we use locus-specific isolation techniques with comparative mapping to characterize the evolution of homoeologous loci in allopolyploid cotton (Gossypium hirsutum) and in species representing its diploid progenitors. We isolated and sequenced 16 loci from both genomes of the allopolyploid, from both progenitor diploid genomes and appropriate outgroups. Phylogenetic analysis of the resulting 73.5 kb of sequence data demonstrated that for all 16 loci (14.7 kb/genome), the topology expected from organismal history was recovered. In contrast to observations involving repetitive DNAs in cotton, there was no evidence of interaction among duplicated genes in the allopolyploid. Polyploidy was not accompanied by an obvious increase in mutations indicative of pseudogene formation. Additionally, differences in rates of divergence among homoeologues in polyploids and orthologues in diploids were indistinguishable across loci, with significant rate deviation restricted to two putative pseudogenes. Our results indicate that most duplicated genes in allopolyploid cotton evolve independently of each other and at the same rate as those of their diploid progenitors. These indications of genic stasis accompanying polyploidization provide a sharp contrast to recent examples of rapid genomic evolution in allopolyploids. (+info)
Chromatin and DNA synthesis associated with nuclear membrane in germinating cotton.
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The synthesis of nuclear DNA and possible attachment sites of chromatin in the cells of cotton (Gossypium barbadense) radicles during germination was investigated. Biochemical analysis of nuclear membrane fragments or Sarkosyl-magnesium-membrane complexes indicates that the DNA, including newly replicated DNA, is attached to the nuclear membranes during periods of active synthesis. Electron micrographs of nuclear membrane fragments indicate a physical association between chromatin fibers and the membranes. The attachment site appears to be proteinaceous, since the chromatin is released by protein degradative enzymes as evidenced by biochemical techniques and electron microscopic observations. Short-term labeling results in incorporation into a membrane-associated product indistinguishable from the bulk of nuclear DNA. DNA polymerase activity is also associated with nuclear membrane preparations in which [3H]thymidine triphosphate is incorporated into an acid-insoluble. DNase-sensitive product. (+info)
Expression pattern of genes encoding farnesyl diphosphate synthase and sesquiterpene cyclase in cotton suspension-cultured cells treated with fungal elicitors.
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Cotton plants accumulate sesquiterpene aldehydes in pigment glands. The two enzymes farnesyl diphosphate synthase (FPS) and (+)-delta-cadinene synthase (CAD), a sesquiterpene cyclase, are involved in the biosynthesis of these secondary metabolites. A full-length cDNA (garfps) encoding FPS was isolated from Gossypium arboreum and identified by in vitro enzymatic assay of the garfps protein heterologously expressed in Escherichia coli. Treatment of G. arboreum suspension-cultured cells with an elicitor preparation obtained from the phytopathogenic fungus Verticillium dahliae dramatically induced transcription of both FPS and CAD, paralleling the accumulation of the sesquiterpene aldehydes in these cells. For G. australe, a wild species from Australia, the V. dahliae elicitor preparation also caused an induction of FPS but only a low rate of induction of CAD, apparently because of a constitutive expression of the sesquiterpene cyclase gene in suspension-cultured cells. Two transcripts and proteins of FPS were detected in the elicited G. australe cells; the smaller FPS seemed to be de novo synthesized after elicitation. Furthermore, G. australe-cultured cells accumulated the cadinene, instead of sesquiterpene aldehydes, indicating that the biosynthetic pathway leading to sesquiterpene aldehydes was absent or blocked after FPP cyclization. (+info)
Expression of a lipid transfer protein gene family during cotton fibre development.
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There are six to eight lipid transfer protein-related genes in the allotetraploid Gossypium hirsutum genome, three of which, FSltp1, FSltp2 and FSltp3, were isolated in two genomic clones. All three genes potentially encode full-length lipid transfer proteins (LTPs), but sequence differences between these and the cotton fibre-specific cDNA previously reported, pFS6, suggest that none is likely to encode the fibre transcripts. Gene-specific RT-PCR experiments showed that expression patterns of the three new LTP genes are similar to each other, with transcripts present in all aerial cotton tissues tested, and only pFS6 transcripts are present in fibre cells at elevated levels. PCR analysis of cotton genomic DNA suggested that FSltp1 and FSltp3 are alloalleles, with FSltp3 being derived from the ancestral A genome, and FSltp1 from the D genome. The fibre-specific gene, yet to be isolated, and FSltp2 are also derived from the ancestral D genome of G. hirsutum. (+info)
Histological changes in the rat common carotid artery following simultaneous topical application of cotton sheet and cyanoacrylate glue.
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Histological changes in and around the arterial walls of rats were investigated following simultaneous topical application of cotton sheet and cyanoacrylate glue. The bilateral common carotid arteries were exposed using sterile techniques, and the test materials were applied to the right artery. The left artery served as a control. Changes in arterial histology were evaluated at 2 weeks, 1 month, 2 months, and 3 months after surgery. Extensive inflammation consisting primarily of histiocytes and multinuclear giant cells was observed around the materials, but tended to decrease by 3 months. Necrosis in the media and fibrosis in the adventitia initially appeared around 2 weeks, and became advanced by 2-3 months. At 2-3 months, disruption of elastic fibers and marked fibrosis in the media were seen, and endothelial proliferation in the intima appeared. Intimal proliferation was observed at both the experimental and other sites of the vessels. The present results suggest that simultaneous use of the test materials can cause the arterial occlusive lesions observed following aneurysmal surgery. (+info)
Clothing for use in clean-air environments.
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Disposable plastic two-piece suits were compared with conventional cotton suits, gowns, and plastic aprons by nurses in a burns unit. The plastic suits allowed fewer micro-organisms to be dispersed into the environment than the other garments but were less comfortable. (+info)
MR characteristics of muslin-induced optic neuropathy: report of two cases and review of the literature.
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Muslin-induced optic neuropathy is a rarely reported but important cause of delayed visual loss after repair of intracranial aneurysms. Most of the previously reported cases were published before the introduction of MR imaging. We describe the clinical features and MR appearance of two cases of delayed visual loss due to "muslinoma," and compare them with the 21 cases reported in the literature. (+info)