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Kinetics of Integration of Xyloglucan into the Walls of Suspension-Cultured Rose Cells 总被引:1,自引:0,他引:1
To study the kinetics of synthesis, wall-binding and degradationof xyloglucan, we incubated suspension-cultured rose cells for0524 h in L-[1-3H]arabinose. >95% of the [3H]arabinosewas taken up within 2 h. UDP-Pentoses were maximally labelledwithin 05 h and had lost most of their 3H by 2 h afterthe addition of [3H]arabinose. Therefore, the 24 h experimentresembled a pulse-chase rgime. The [3H]xyloglucan formed wasfractionated into four cellular pools [detergent-extractable(interpreted as cytoplasmic), and guanidinium thiocyanate-,06 M NaOH- and 60 M NaOH-extractable (interpreted as progressivelymore firmly wall-bound)]; soluble extracellular xyloglucan wascollected as a fifth pool. All five pools of xyloglucan hadstarted accumulating 3H at their respective maximal rates by 相似文献
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Geographic analysis of nucleotide diversity and song sparrow (Aves: Emberizidae) population history 总被引:2,自引:0,他引:2
Mitochondrial DNA (mtDNA) control-region (CR) sequences were analysed to address three questions regarding the evolution of geographical variation in song sparrows. (i) Are mtDNA sequences more informative about phylogenetic relationships and population history than previously published restriction fragment (RFLP) data? (ii) Are song sparrow CR sequences evolving in a selectively neutral manner? (iii) What do the haplotype cladogram and geographical pattern of nucleotide diversity (π) suggest about the recent evolutionary history of song sparrow populations? Results from phylogenetic analyses of CR sequences corroborate RFLP results and reveal instances in which haplotypes do not group by locality. Neutrality tests ( 51 ) suggest that song sparrow mtDNA is evolving in a selectively neutral manner, although exceptions are noted. A novel geographical pattern of π suggests a model of song sparrow population history involving multiple Pleistocene refugia and colonization of some formerly glaciated regions from multiple sources. Moreover, application of coalescence theory to the haplotype cladogram suggests that two different haplotypes (48NF and 151HA) may have predominated in different parts of the song sparrow's range. This model provides insight into the current distribution of song sparrow mtDNA haplotypes and may explain the discordance between evolutionary history inferred from mtDNA and morphology in this species. 相似文献
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SUMMARY. 1. Methods for the quantitative removal of epiphyton from Cladophora glomerata were compared.
2. Stomaching for 3–5 min effected maximum epiphyte release. Agitation for up to 40 min in water or hydroiysing solutions of hydrochloric acid or F.A.A. removed significantly fewer epiphytes.
3. Stomaching is recommended as a new, simple, quick and effective method for quantitative epiphyton sampling. 相似文献
2. Stomaching for 3–5 min effected maximum epiphyte release. Agitation for up to 40 min in water or hydroiysing solutions of hydrochloric acid or F.A.A. removed significantly fewer epiphytes.
3. Stomaching is recommended as a new, simple, quick and effective method for quantitative epiphyton sampling. 相似文献
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The role of epinephrine in the secretion of the adrenal cortex 总被引:2,自引:0,他引:2
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Three analogue- and two microprocessor-based methods for estimatingleaf area were compared for accuracy, variability and speed,on 200 leaf templates of known area and contrasting shape (bipinnatifid,ensiform, elliptic and triangular). The data were analyzed intwo blocks for each shape; 相似文献
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The quantitatively major nonasaccharide (XG9) derived from xyloglucanby digestion with cellulase exhibits anti-auxin activity inthe pea stem segment straight-growth bioassay; the most effectiveconcentration of XG9 is c. 109 M. Previous work had shownthat XG9 owes its biological activity to the presence of a terminal-L-fucopyranose residue. In order to investigate to what extentthe remainder of the XG9 molecule is essential for activity,several fucose-containing compounds were tested for their abilityto mimic the anti-auxin effect of XG9. A fucose-containing pentasaccharideof xyloglucan (XG5; probable structure FucGalXylGlcGlc) was,at 108 M, about as effective an anti-auxin as 109M XG9; unlike XG9, XG5 did not diminish in effectiveness at107 M. The human milk trisaccharide, 2'-fucosyl-lactose[L-fucopyranosyl--(12)-D-galactopyranosyl-ß-(14)-D-glucose],whose FucGal unit is identical with that of XG9, inhibited auxin-inducedelongation over a wide range of concentrations centred on about108 M. 2'-Fucosyl-lactose at 108 M was about aseffective an anti-auxin as 109 M XG9. Free L-fucose andmethyl--L-fucopyranoside were unable to inhibit auxin-inducedgrowth at any concentration tested (1010 M to 106M) and neither compound interfered with the inhibition causedby 109 M XG9 when co-incubated at concentrations up to104 M. The results confirm the essential r?le of an -linkedterminal fucose residue in the anti-auxin activity of XG9 andshow that the sub-terminal galactose residue may also be required.Possible reasons why high concentrations of XG9 fail to antagonizeauxin-induced growth while high concentrations of XG5 and 2'-fucosyl-lactosecontinue to do so are discussed. Key words: Anti-auxin, oligosaccharin, fucose 相似文献
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A single specimen (Fig. 1), found dead on an islet off Port Sudan in spring 1984 is described as a distinctive new allospecies of African Cliff Swallow Hirundo spilodera. 相似文献