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Tobacco leaves depleted of starch, were detached and allowedto assimilate equal amounts of 14CO2 and 12CO2in succession,and vice versa. Distribution of radioactivity in starch, andsugars was determined after assimilation and after disks cutfrom the leaves had been kept in darkness for times up to 40hours. The amount and activity of the CO2 was also determined.14C and 12C were incorporated in equal amounts into starch independentlyof the order in which they were supplied. In contrast sucrosehad high activity 14C was given last, and hexose a low one.The reverse was true when 12C was given last. Activity of respiratoryCO2 was slightly higher when 14C was assimilated last as comparedwith 12C. In the dark only 14C or 12C was at first lost fromstarch, in accordance or removal of discrete layers. Analyticalresults show that starch is the main respiratory substrate andto account for the redistribution of radioactivity in passageto CO2 it is concluded that sucrose occurs at two sites separatedinter-or intra-cellularly, one of which is in equilibrium withthe system intrconverting starch and CO2 and at the other hexosesare produced by inversion. A starch-like polysaccharide is formedduring assimilation which persists in the dark and there isa significant contribution to respiration of carbon from non-carbohydratesources when leaf disks are kept on the dark. 相似文献
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A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
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FITZ JOHN PORTER POOLE 《The Australian journal of anthropology》1984,14(3):191-216
The Bimin-Kuskusmin of the West Sepik interior of Papua New Guinea elaborate a complex folk theory of procreation that becomes the ‘natural’ foundation of some ideologically significant constructions of the individual, the person, gender, and societal continuity. Drawing on certain aspects of Weiner's model of reproduction and regeneration, symbols of substance and insubstantial ‘spirit’ that form this ‘natural’ foundation of the Bimin-Kuskusmin ideology of birth, death, and rebirth are explored in contexts of rites of passage that mark the course of the life-cycle from conception to death and ancestorhood. The key symbols of this cultural ideology are the enduring substances of bone, bone marrow, and finiik spirit, which are the basis of reckoning the cyclical regeneration of clan categories. 相似文献
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K. J. DOUGHTY A. J. R. PORTER A. M. MORTON G. KIDDLE C. H. BOCK R. WALLSGROVE 《The Annals of applied biology》1991,118(2):469-477
The glucosinolate content of oilseed rape {Brassica napus) leaves was monitored over the growth period 30–70 days after planting, and a comparison made between a single-low cultivar (low in erucic acid), Bienvenu, and a double-low cultivar (low in erucic acid and glucosinolate), Cobra. In older, fully-expanded leaves the glucosinolate concentration was very low (< 0.3 μmol/ml tissue water) and did not alter during the course of the experiment. In developing sixth leaves glucosinolate content increased rapidly and reached a maximum concentration (4–5 μmol/ml tissue water) 40 days after planting (6 days after leaf emergence). The concentration then declined, to about 1 μmol/ml after 60 days although the total glucosinolate content in leaves continued to increase until 50 days; much of the reduction in concentration was simply a result of leaf expansion. No major differences were seen between the two varieties in total glucosinolate content or in the individual compounds present. Cv. Cobra developed more quickly than cv. Bienvenu so direct comparison between leaves of the two cultivars was complex. When comparing the glucosinolate content of oilseed rape leaves, between cultivars or between treatments, it is vital to ensure that carefully matched leaves of comparable developmental age are selected. 相似文献
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Abstract.
- 1 Mark—recapture sampling must be stratified because populations of foragers and defenders are partitioned by trunk trails and order of emergence respectively.
- 2 Foragers and defenders form overlapping subsets of the total colony population, each of which is correlated with total colony population size.
- 3 Foragers and defenders have an average life expectancy of approximately 2 weeks.
- 4 The fluorescent marking procedure did not significantly affect harvester ant mortality and only temporarily affected their behaviour.
- 5 Combinations and mixtures of fluorescent ink allow at least eight groups in a colony to be distinctly marked for periods exceeding 4 months.
10.
Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu. 相似文献