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  • Heavy metals  (2)
  • Recombinations  (2)
  • chromosome pairing  (2)
  • 1
    ISSN: 1572-8773
    Schlagwort(e): Heavy metals ; Efflux of Na+ and K+ ; Nostoc muscorum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary This study presents the effects of Cr, Pb, Ni and Ag on growth, pigments, protein, DNA, RNA, heterocyst frequency, uptake of NH4 + and N03 −, loss of electrolytes (Na+ and K+), nitrate reductase and glutamine synthetase activities ofNostoc muscorum. The statistical tests revealed a direct positive correlation between the metal concentration and inhibition of different processes. Ni was found to be more toxic against growth, pigments and heterocyst differentiation compared to the other metals. Inhibition of pigment showed the following trend: chlorophyll 〉 phycocyanin 〉 carotenoid. No generalized trend for inhibition of macromolecules was observed. The loss of K+ and Na+ as affected by Cr, Ni and Pb was similar but more pronounced for K+ than Na+. The inhibition of physiological variables depicted the following trend: Na+ loss 〉 K+ loss 〉 glutamine synthetase 〉 NH4 uptake 〉 growth 〉 N03 − uptake 〉 nitrate reductase 〉 heterocyst frequency. This study therefore suggests that loss of electrolytes can be used as a first signal of metal toxicity in cyanobacteria. However, further study is needed to confirm whether the abnormality induced by nickel (branch formation) is a physiological or genetic phenomenon.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0495
    Schlagwort(e): Key words Damodar River ; Heavy metals ; Grain size ; Chemical fractionation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  The distribution of Si, Al, Fe, Mn, Cu, Zn, Ni and Cr in different grain-size fractions and geochemical association of Fe, Mn, Cu and Zn with 〈63-μm size fraction of bed sediments of Damodar River has been studied. In general, concentrations of heavy metals tend to increase as the size fractions get finer. However at two sites, near mining areas, the coarser particles show similar or even higher heavy metal concentrations than finer ones. The higher residence time and/or presence of coarser particles from mining wastes are possibly responsible for higher metal content in the coarser size fractions. The chemical fractionation study shows that lithogenic is the major chemical phase for heavy metals. Fe and Mn are the major elements of the lithogenic lattice, constituting 34–63% and 22–59%, respectively, of total concentrations. Fe-Mn oxide and organic bound fractions are significant phases in the non-lithogenic fraction. The carbonate fraction is less significant for heavy metal scavenging in the present environment and shows the following order of abundance Zn〉Cu〉Mn〉Fe. The exchangeable fraction of the Damodar sediments contains very low amounts of heavy metals suggesting poor bioavailability of metals.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 72 (1986), S. 164-169 
    ISSN: 1432-2242
    Schlagwort(e): Arachis ; Autotetraploid ; Chromosome pairing ; Genomic relationships ; Recombinations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Autotetraploids were established from 8 diploid wild species of section Arachis. In all the autotetraploids the chromosomes paired largely as bivalents even though they possess the ability to pair as multivalents. Pollen and pod fertility in the C1 generation were not directly associated with chromosome pairing. The C2 generation autotetraploids showed a gradual increase in bivalent associations and pollen and pod fertility. The identification of two genomes, A and B, in the diploid species and in the tetraploid, A. hypogaea, of the section Arachis, a fairly good crossability, and the type of chromosome associations observed in hybrids between A. hypogaea and the autotetraploids of wild Arachis species indicated good prospects of utilizing autotetraploids as genetic bridges in transferring desired traits from these taxa into groundnut.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 72 (1986), S. 433-439 
    ISSN: 1432-2242
    Schlagwort(e): Arachis ; Amphidiploids ; Genomes ; Chromosome pairing ; Recombinations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Synthetic amphidiploids were established in 32 combinations involving 8 diploid wild species representing both A and B genomes of section Arachis. Bivalent and multivalent associations in the amphidiploids of 7 A genome species confirm that these species have identical genomes. Contrastingly, high bivalent frequencies in amphidiploids involving the A and B genome species suggest that A. batizocoi has a distinct ‘B’ genome that is partially homologous to the other genome ‘A’ represented in the rest of the species. Crossability, chromosome pairing and pollen and pod fertility in hybrids between A. hypogaea and amphidiploids have revealed that these amphidiploids can be used as a genetic bridge for the transfer of genes from the wild species into the cultivated groundnut.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 160 (1988), S. 143-151 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Fabaceae ; Arachis hypogaea ; Amphidiploids ; chromosome pairing ; genome ; putative ancestors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chromosome pairing, pollen and pod fertility in hybrids between cultivated tetraploidArachis hypogaea and 15 synthetic amphidiploids from 8 diploid species (7 of the A genome and 1 of the B genome) of sect.Arachis have been utilized for the identification of putative genome donors in the evolution of cultivatedA. hypogaea. These results, in conjunction with evidence from morphological similarities, phytogeographical distribution and some phytochemical features, confirm the segmental amphidiploid origin ofA. hypogaea. A. batizocoi andA. duranensis are suggested as the donors of the B genome and the A genome respectively.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 147 (1984), S. 237-252 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Cucurbitaceae ; Cucumis ; Interspecific crossability ; chromosome pairing ; pollen fertility ; phylogenetic relationship ; karyomorphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Investigations on interspecific crossability in 8Cucumis species (2n = 24) and chromosome pairing and pollen fertility of their hybrids from 15 combinations have been utilized for tracing the phylogenetic relationships among these taxa and factors responsible for their differentiation. A collective evaluation of data suggests that there are three broad groups of species, one of the spiny fruited interfertile species, whose hybrids show varying degree of chromosome associations and low to high pollen fertility; the second of species with non-spiny fruits, which are completely incompatible with the former but weakly compatible with the cultivated species,C. melo L. to produce partly developed seeds, and the third group ofC. metuliferus E. Mey. exSchrad. andC. melo and its different botanical varieties. The species with spiny fruits can be further divided based on karyomorphological similarities and/or on relative genomic affinity, indicated by chromosome pairing and hybrid pollen fertility.
    Materialart: Digitale Medien
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