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  • 1
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    Macrofossil evidence for a rapid and severe Cretaceous–Paleogene mass extinction in Antarctica (2016)
    Springer Nature
    Details
    Publikationsdatum: 2016-05-28
    Beschreibung: Article Debate surrounds the causes, timing, and effects of the Cretaceous-Paleogene mass extinction, 66 Ma. Here, using new collections of marine macrofossils from Seymour Island, Antarctica, the authors show that the extinction was both rapid and severe in the high southern latitudes, contrary to previous studies. Nature Communications doi: 10.1038/ncomms11738 Authors: James D. Witts, Rowan J. Whittle, Paul B. Wignall, J. Alistair Crame, Jane E. Francis, Robert J. Newton, Vanessa C. Bowman
    Digitale ISSN: 2041-1723
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft , Physik
    Publiziert von Springer Nature
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  • 2
    Digitale Medien
    Digitale Medien
    The Perfect Buffer (1946)
    [s.l.] : Nature Publishing Group
    Nature 158 (1946), S. 586-586 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] CONSIDER a solution containing (a) equivalents of a weak acid, HA, and (b) equivalents of a strong base. For this to be a perfect buffer it may presumably be stated that the rate of change of pH with added acid or base must be a minimum; that is, dpH/db is to be a minimum, or ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/158586a0
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  • 3
    Digitale Medien
    Digitale Medien
    Copy numbers of chloroplast and nuclear genomes are proportional in mature mesophyll cells of Triticum and Aegilops species (1986)
    Springer
    Planta 167 (1986), S. 264-274 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Aegilops ; Chloroplast DNA ; DNA, chloroplast and nuclear ; Ploidy ; Triticum (chloroplast and nuclear genomes)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The possibility of estimating the proportion of chloroplast DNA (ctDNA) and nuclear DNA (nDNA) in nucleic-acid extracts by selective digestion with the methylation-sensitive restriction enzyme PstI, was tested using leaf extracts from Spinacia oleracea and Triticum aestivum. Values of ctDNA as percentage nDNA were estimated to be 14.58%±0.56 (SE) in S. oleracea leaves and 4.97%±0.36 (SE) in T. aestivum leaves. These estimates agree well with those already reported for the same type of leaf material. Selective digestion and quantitative dot-blot hybridisation were used to determine ctDNA as percentage nDNA in expanded leaf tissue from species of Triticum and Aegilops representing three levels of nuclear ploidy and six types of cytoplasm. No significant differences in leaf ctDNA content were detected: in the diploids the leaf ctDNA percentage ranged between 3.8% and 5.1%, and in the polyploids between 3.5% and 4.9%. Consequently, nuclear ploidy and nDNA amount were proportional to ctDNA amount (r(19)=0.935, P〉0.01) and hence to ctDNA copy number in the mature mesophyll cells of these species. There was a slight increase in ctDNA copy numbers per chloroplast at higher ploidy levels. The balance between numbers of nuclear and chloroplast genomes is discussed in relation to polyploidisation and to the nuclear control of ctDNA replication.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00391425
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  • 4
    Digitale Medien
    Digitale Medien
    Autopolyploidy in Dactylis glomerata L.: further evidence from studies of chloroplast DNA variation (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 393-399 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Autopolyploidy ; Chloroplast DNA variation ; Dactylis glomerata L. ; Intraspecific evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chloroplast DNA variation has been used to examine some of the maternal lineages involved in the evolution of the intraspecific polyploid complex, Dactylis glomerata L. Diploid (2x) and tetraploid (4x) individuals were collected from natural populations of the subspecies glomerata (4x), marina (4x) and lusitanica (2x), as well as from sympatric 2x/4x populations of the Galician type. Digestion of their ctDNA with 11 restriction endonucleases revealed enough variation to characterise three ctDNA variants, designated MBMK, MBmK and mBMK. The distribution of these ctDNA variants reflects different stages in their spread among the populations. The MBMK ctDNA variant predominated at both ploidy levels in subspecies glomerata, lusitanica and marina, and in recent tetraploid Galician/glomerata hybrids. The MBmK variant was detected in a single tetraploid individual and probably results from a relatively recent mutation. Fixation of the mBMK minority variant in the diploid and tetraploid Galician populations adds to the evidence concerning the possible origin of the Galician tetraploids. It means that the Galician diploids were maternal ancestors of the tetraploids. This result complements evidence from earlier studies based on morphology or biochemical markers, and reduces the likelihood that the tetraploids arose by hybridisation between an ancient Galician diploid and an alien tetraploid. It is, however, consistent with a true autopolyploid origin of the tetraploids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00265302
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  • 5
    Digitale Medien
    Digitale Medien
    Excitatory amino acids directly depolarize rat brain astrocytes in primary culture (1984)
    [s.l.] : Nature Publishing Group
    Nature 311 (1984), S. 656-659 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] When astrocytes were bathed in a solution of L-Glu (104 M), rapid depolarization was detected, followed by a slow repolarization in the continued presence of L-Glu (Fig. la). The removal of L-Glu resulted in a rapid repolarization which was followed by a transient hyperpolarization and then a ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/311656a0
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  • 6
    Digitale Medien
    Digitale Medien
    Chloroplast DNA variation between species of Triticum and Aegilops. Location of the variation on the chloroplast genome and its relevance to the inheritance and classification of the cytoplasm (1983)
    Springer
    Theoretical and applied genetics 65 (1983), S. 247-262 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Triticum ; Aegilops ; Chloroplast DNA ; Cytoplasmic inheritance ; Wheat evolution ; The B genome donor ; Restriction mapping ; Insertions ; Deletions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Restriction endonuclease analysis revealed interspecific and intraspecific variation between the chloroplast DNAs and therefore between the cytoplasms of 14 selected species of Triticum and Aegilops. Eleven distinct chloroplast DNA types were detected, the differences between them residing in the varied combination of a relatively few DNA alterations. The variation was simple enough for chloroplast DNA analysis to be used as a basis for the identification and classification of the Triticum and Aegilops cytoplasms. There was good agreement with the classification based on analysis of the phenotypic effects of the cytoplasm when combined with the T. aestivum nucleus in nuclear-cytoplasmic hybrids (Tsunewaki et al. 1976). There was however no correlation between specific chloroplast DNA alterations and any of the phenotypic effects known to be associated with specific cytoplasms. Although the diploid species examined included all those which have been suggested as possible donors of the cytoplasm and the B genome to T. aestivum, none of the chosen accessions belonged to the same cytoplasmic class as T. aestivum itself, except that of the tetraploid T. dicoccoides. Therefore, none of the diploid accessions analysed was the B genome donor. The analyses did however support several other suggestions which have been made concerning wheat ancestry. Scoring the different chloroplast DNA types according to the rarity of their banding patterns indicated that four of the eleven cytoplasms are of relatively recent origin. The DNA alterations most easily detectable by the limited comparison of the eleven Triticum/Aegilops chloroplast DNA types using only 4 endonucleases were insertions and deletions. These ranged between approximately 50 bp and 1,200 bp in size and most of them were clustered in 2 segments of the large single-copy region of the genome. Only two examples of the loss of restriction endonuclease sites through possible point mutations were observed. No variation was detected in the inverted repeat regions. Several of the deletions and insertions map close to known chloroplast protein genes, and there is also an indication that the more variable regions of the chloroplast genome may contain sequences which have allowed DNA recombination and rearrangement to occur.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00308076
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  • 7
    Digitale Medien
    Digitale Medien
    Studies on feeding in the soil predatory mitePergamasus longicornis (Berlese) (Mesostigmata: Parasitidae) using dipteran and microarthropod prey (1987)
    Springer
    Experimental and applied acarology 3 (1987), S. 201-206 
    Details
    ISSN: 1572-9702
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Larvae ofMusca domestica andDrosophila melanogaster were tested as prey for adultPergamasus longicornis using soil microarthropods as controls. Fly larvae were fed upon for a longer time and almost continuously. Second-instar larvae ofM. domestica were not eaten completely. No differences were detected between the sexes of the predator. Final-instar larvae ofD. melanogaster were chosen for subsequent experimentation. New field records of soil prey are included.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01270455
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  • 8
    Digitale Medien
    Digitale Medien
    Studies of the protein content of individualPergamasus longicornis (Berlese) (Acari: Mesostigmata: Parasitidae) (1985)
    Springer
    Experimental and applied acarology 1 (1985), S. 345-355 
    Details
    ISSN: 1572-9702
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The protein content ofPergamasus longicornis (Berlese) individuals is of the order of 45 μg bovine serum albumen equivalents and varies depending on gender, time of year and gut colour (postulated nutritive state). Variation between males and females closely matches their size difference. A sinusoidal relationship with a late spring/early summer maximum and a late autumn/early winter minimum is shown for females. Gut colour is a useful predictor in females only. Pregnancy and prey utilisation over the year are suggested as important determinants of protein content and are discussed in detail.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201573
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  • 9
    Digitale Medien
    Digitale Medien
    Characterization of coal-mine refuse as backfilling material (1996)
    Springer
    Geotechnical and geological engineering 14 (1996), S. 129-150 
    Details
    ISSN: 1573-1529
    Schlagwort(e): mine refuse ; backfilling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Summary With increased production and more stringent regulations for air, water and ground pollution control, the safe and environmentally acceptable disposal of coal-mine refuse is becoming ever more demanding. Backfilling may provide an environmentally acceptable method for the disposal of waste materials. Increased resource recovery, enhanced ventilation control, and minimizing surface subsidence, underground coal-mine fires and spontaneous combustion of coal are potential advantages of backfilling. In this paper the physical and mechanical properties of coal-mine waste from different sites are described and the effects of these properties on the duty requirements of fill material are assessed. As a result of testing, it is concluded that if improving ground control is the only reason for backfilling, coal refuse alone does not appear to be a suitable stowing material. If coal-refuse disposal is also a consideration, then it may be more attractive as a stowing material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00430273
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  • 10
    Digitale Medien
    Digitale Medien
    Chloroplast transfer RNAs and tRNA genes of wheat (1985)
    Springer
    Plant molecular biology 4 (1985), S. 315-320 
    Details
    ISSN: 1573-5028
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Fractionation (by two-dimensional polyacrylamide gel electrophoresis) of total tRNA from wheat chloroplasts yields about 33 RNA spots. Of these, 30 have been identified by aminoacylation as containing tRNAs specific for 17 amino acids. Hybridization of labeled individual tRNAs to cloned chloroplast DNA fragments has revealed the location of at least nine pairs of tRNA genes in the segments of the inverted repeat, at least twelve tRNA genes in the large single copy region and one tRNA gene in the small single copy region. A comparison of this wheat chloroplast tRNA gene map to that of maize and of other higher plants suggests that gene rearrangements have occurred during evolution, even within cereal chloroplast DNA. These rearrangements have taken place within the inverted repeat, within the large single copy region and between the inverted repeat and the large single copy region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02418251
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