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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 101 (2000), S. 1234-1241 
    ISSN: 1432-2242
    Keywords: Key words Diplotaxis ; Brassicaceae ; ISSR-PCR ; Genetic relationships ; Molecular taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Inter-simple sequence repeat (ISSR) amplification was evaluated for its applicability as a genetic marker system to establish relationships among ten Diplotaxis species. ISSR amplification generated multiple banding profiles with the 12 primers from all DNA samples, with an average of 41.2 fragments per primer. This average was clearly higher for the 5´ triple-anchored primers than for other primers. The banding profiles were highly repeatable across separate PCR runs. DNA mixing procedures were found to be appropriate strategies to generate banding patterns representative of each species studied. Similarity values were calculated considering 494 ISSR bands, and a dendrogram was constructed based on the similarity matrix. The ten Diplotaxis species were clustered into two major groups. The first group consists of five species, Diplotaxis tenuifolia and Diplotaxis cretacea, and Diplotaxis muralis with their putative parents (D. tenuifolia and Diplotaxis viminea). In the second group three species are clustered that are closely related (Diplotaxis virgata, Diplotaxis catholica and Diplotaxis siettiana), in addition to Diplotaxis harra, and Diplotaxis erucoides, which has lowest similarity values with the rest of the species studied. The two groups defined in the present work may be concordant with the idea suggested by several authors of a biphyletic origin for Diplotaxis. The genetic relationships among the ten Diplotaxis species estimated by the polymorphism of ISSR markers are in agreement with those previously inferred by other morphological, biochemical and molecular data, indicating the reliability of the ISSR approach for this purpose.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 5 (1987), S. 120-125 
    ISSN: 1432-0789
    Keywords: Fungal melanins ; Humic acid ; Infrared analysis ; Free radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Humic acid-type polymers (melanins) synthesized in culture media by the fungi Aspergillus glaucus, Eurotium echinulatum, Hendersonula toruloidea, Stachybotrys atra and Aspergillus sydowi were analysed for elemental composition, functional group content, infrared (IR) and electron spin resonance (ESR) properties. Results were discussed in comparison with range values referred for soil humic acids. The fungal polymers showed significant differences in carboxyl and nitrogen content and C/H atomic ratios, reflecting a different degree of condensation (aromaticity) among the various samples. IR analysis gave evidence of: (a) the predominant aromatic character of melanins from A. glaucus, E. echinulatum and H. toruloidea; (b) the high content of aliphatic and olefinic components of S. atra melanin; (c) the typical presence of amide bonds in the nitrogen-richest melanins from A. sydowi and H. toruloidea; and (d) the generally low amount of free carboxyl groups, which often appeared involved in hydrogen bonds. ESR spectra showed that all the melanins studied contained appreciable concentrations of organic free radicals of prevailing semiquinonic nature and of the same order of magnitude commonly measured in humic acids from soil and other sources. The free electron concentration was shown to be directly related to the C/H atomic ratio and to the degree of aromaticity shown by IR analysis. This indicated that the highest free radical content in the melanins from E. echinulatum and A. glaucus was associated with the highest presence of condensed aromatic structures. Humic acid-type polymers synthesized by soil fungi may, therefore, contribute to the total free radical content of soil humic substances and play important roles in all reactions involving free radicals in soils and related environments.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: Biodegradation ; Biomass ; Carbon ; Cornstalks ; Humus formation ; Wheat straw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of soil type and incubation period on the biodegradation, incorporation into biomass, and stabilization in humus of14C-labeled cornstalk and/or wheat straw lignin, polysaccharide, and protein fractions were followed for one year. After 6 months, 56–68%, 6–21%, 71–81%, 63–75%, and 56–68% from wheat straw and from the lignin, polysaccharide, and protein fraction of wheat straw had been lost as CO2, respectively. Loss of CO2 increased only slightly with further incubation. Greater amounts of CO2, especially during the early incubation stages, were evolved from neutral and alkaline soils (pH 7.0, 7.4, 7.8) than from acid soils (pH 5.0, 5.5). After one year, a major portion of the residual C from lignin was recovered in the humic acid fraction, relatively small amounts, 5 to 17%, were lost upon acid hydrolysis, and generally 〈1% was found present in the biomass. Lesser amounts of the polysaccharide and protein carbons were incorporated into the humic acid, 17–20% and 16–27%, respectively. Relatively greater amounts of the residual carbons of the polysaccharide and protein were incorporated into the biomass, 4.9–7.8% and 4.6–13.4%, respectively and higher percentages were lost upon acid hydrolysis, 56 to 81%. The results for the whole wheat straw were very similar to those of the protein fraction. Overall, more residual C was stabilized into humic acid in the acid soils than in the neutral soils.
    Type of Medium: Electronic Resource
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