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  • 1
    ISSN: 1432-2048
    Keywords: Nuclear envelope ; Nuclear vacuoles ; Meiosis ; Prophase ; Sporogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vacuoles formed by the invagination of the inner membrane of the nuclear envelope have been observed during meiotic prophase in a wide range of plants. In the angiosperm Lycopersicon their formation was found to coincide with the completion of synaptonemal complex formation, and this timing is analogous to that observed during this stage in the silkworm Bombyx. The implications of this activity in relation to the process of chromosome movement are discussed. In the gymnosperm Pinus, the heterosporous fern Marsilea and homosporous ferns Pteridium and Dryopteris the formation of nuclear vacuoles begins much earlier, coinciding with the condensation of chromatin during leptotene. They enlarge and become more elaborate as meiosis proceeds, and may eventually become detached from the nuclear envelope. It is therefore thought unlikely that theyfulfil functions connected with chromosome movement in the manner proposed for the silkworm and the tomato. During diplotene/diakinesis they contain electron-opaque granules and fibrils, and the possible origin and significance of this material is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 80 (1980), S. 57-68 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A developmental gradient was confirmed by sequential transverse sections of tomato anthers and used to determine the sequence of chromosome behaviour during meiotic prophase. Most of meiosis corresponds to earlier descriptions, but two unusual behaviours were observed, the aggregation of the chromosomes into a synizetic knot during zygotene, and the delayed contraction of chromosomes during a diffuse stage after pachytene. Both behaviours were found in pollen mother cells of species in the genera Lycopersicon, Solanum, Nicotiana, Capsicum and Datura, and in egg mother cells of the cultivated tomato and of Solanum pennellii.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract From crosses within a 2n = 43 line of Syrian hamsters (Mesocricetus auratus) lacking one derivative (der 11) of an 11;20 reciprocal translocation we have obtained homozygotes with only 42 chromosomes These animals are homozygous deficient (nullisomic) for the centromere and short arm of chromosome 11 and for the bulk of the long arm of chromosome 20. — During cytogenetic studies, we investigated the frequency patterns of early-replicating bands in the surviving derivative (der 20) at two cytologically defined sub-phases of S using short-term fibroblast cultures. These patterns were compared with those observed in the component, untranslocated arms in normal 2n = 44 cells at the same two sub-phases. — Very close agreement was found, indicating that neither the nullisomy, nor the new arm combination has interfered detectably with the pattern or programme of early band replication.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 83 (1981), S. 711-720 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The BrdU/Hoechst 33258/Giemsa method for sub-dividing S-phase in asynchronous cell populations has been re-evaluated and modified to give better definition and more even distribution of sub-phases. A reference pattern of early-relicating euchromatic bands is given for all chromosomes at Sk2 in primary cultures of skin fibroblasts. The overall band patterns at each sub-phase have allowed more objective definitions of “early” and “late” replication for these cells, and show that in both classes of chromatin light G-bands preceed dark G-bands. Asynchrony between homologous bands is observed at all stages of S, albeit with a variable frequency. The observed in vitro replication patterns and programme for the chromosomes of skin fibroblasts does not appear to be affected by the age or sex of the source.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 84 (1981), S. 365-372 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The sub-division of S-phase in Syrian hamsters, on the basis of BrdU/Hoechst 33258/Giemsa banding, has allowed a quantitative comparison of the replication of individual chromosome bands within defined subphases of S. This analysis has shown that in hamsters, as has been reported in humans, there are distinct patterns of early replication in vitro in the early X, the late X in fibroblasts, and the late X in lymphocytes. In addition, it has been possible to show that, although the pattern of replication of the late X in fibroblasts differs from that in lymphocytes, the time in S at which bands first appear on this chromosome is the same in the two cell types. — No significant heterogeneity can be ascribed to differences between individuals, adult or embryonic sources, culture media, or time of exposure to BrdU. — The absence of any detectable heterogeneity in the replication band frequencies in autosomal heterochromatic arms suggests that the cell-specific variability of the late-replicating X is a feature of facultative rather than constitutive heterochromatin.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 91 (1985), S. 164-166 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Untransformed Syrian hamster fibroblasts in exponential growth were exposed to a pulse of [3H]-thymidine for 5 min, followed immediately by bromodeoxyuridine, and serial samples were taken up to 16 h. Preparations were autoradiographed and stained for replication banding. No cell with replication bands was found without significant [3H]-thymidine uptake, although the extent of uptake varied between sub-phases of S. Thus there is no indication of a total cessation of synthesis at any period during S-phase.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 98 (1989), S. 301-306 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Chromosome behaviour during meiosis in male Syrian hamsters heterozygous for one of three translocations was analysed as part of a study of the transmission of these structural changes. Synapsis was studied using preparations of synaptonemal complexes, and chiasmate associations and the results of anaphase I segregation were studied in air-dried preparations of metaphases I and II respectively. The main findings were: (i) that, at least in the two trivalent-forming translocations, there is no simple relationship between either the frequency or the extent of synapsis and chiasma formation between the chromosomes involved in the translocation; (ii) that the presence of a univalent in a substantial proportion of metaphase I cells does not necessarily lead to irregular segregation as judged by analysis of metaphase IIs; and (iii) conversely, that in translocation heterozyotes in which metaphase I contains the chromosomes involved in the translocation as a quadrivalent or as two bivalents, with no univalents or trivalents, unexpected numerical segregation can be found. The observations of meiotic chromosomes behaviour reported here show that it is not always possible to predict the effects of structural change, or to determine the basis of these effects, from an analysis of any stage of meiosis taken in isolation, or from an analysis of an apparently similar change.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2023-11-09
    Keywords: Biovolume calculated from equivalent spherical diameter (ESD); Copepoda; Copepoda, biovolume; DATE/TIME; Depth, bottom/max; Depth, top/min; DEPTH, water; MON; Monitoring; Plankton, biovolume; Plankton abundance; Point_B; Sample code/label; Uniform resource locator/link to graphic; Uniform resource locator/link to thumbnail; Villefranche sur Mer, France; ZOOSCAN
    Type: Dataset
    Format: text/tab-separated-values, 234 data points
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  • 9
    Publication Date: 2023-11-09
    Keywords: Biovolume calculated from equivalent spherical diameter (ESD); Copepoda; Copepoda, biovolume; DATE/TIME; Depth, bottom/max; Depth, top/min; DEPTH, water; MON; Monitoring; Plankton, biovolume; Plankton abundance; Point_B; Sample code/label; Uniform resource locator/link to graphic; Uniform resource locator/link to thumbnail; Villefranche sur Mer, France; ZOOSCAN
    Type: Dataset
    Format: text/tab-separated-values, 243 data points
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  • 10
    Publication Date: 2023-11-09
    Keywords: Biovolume calculated from equivalent spherical diameter (ESD); Copepoda; Copepoda, biovolume; DATE/TIME; Depth, bottom/max; Depth, top/min; DEPTH, water; MON; Monitoring; Plankton, biovolume; Plankton abundance; Point_B; Sample code/label; Uniform resource locator/link to graphic; Uniform resource locator/link to thumbnail; Villefranche sur Mer, France; ZOOSCAN
    Type: Dataset
    Format: text/tab-separated-values, 234 data points
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