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  • 1990-1994  (3)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    High resolution detection of uncoated metaphase chromosomes by means of field emission scanning electron microscopy (1994)
    Springer
    Chromosoma 103 (1994), S. 393-400 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract HeLa metaphase chromosomes were exammed by means of “in lens” field emission scanning electron microscopy, which permits high resolution detection of uncoated biological samples. By using uncoated chromosomes as a model for comparison we report evidence of how traditional scanning electron microscopy techniques such as metal coating and conductive methods can generate errors in chromosome structure evaluation, since both give rise to morphological artifacts. By comparing the morphology of uncoated chromosomes obtained by two different isolation procedures, such as that utilized in standard cytogenetics and the polyamine method, we have drawn the following conclusions: (a) the standard cytogenetic method gives rise to a chromosome structure consisting of a flattened network of 10 nm fibers, in which higher order chromatin organization is absent. (b) Chromosomes obtained by the polyamine method show both three-dimensional profile and higher level folding of chromatin fibers, supporting the loop chromosome organization previously suggested by scanning electron microscopy observation of hexylene glycol isolated chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00362283
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    High resolution detection of uncoated metaphase chromosomes by means of field emission scanning electron microscopy (1994)
    Springer
    Chromosoma 103 (1994), S. 393-400 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. HeLa metaphase chromosomes were examined by means of “in lens” field emission scanning electron microscopy, which permits high resolution detection of uncoated biological samples. By using uncoated chromosomes as a model for comparison we report evidence of how traditional scanning electron microscopy techniques such as metal coating and conductive methods can generate errors in chromosome structure evaluation, since both give rise to morphological artifacts. By comparing the morphology of uncoated chromosomes obtained by two different isolation procedures, such as that utilized in standard cytogenetics and the polyamine method, we have drawn the following conclusions: (a) the standard cytogenetic method gives rise to a chromosome structure consisting of a flattened network of 10 nm fibers, in which higher order chromatin organization is absent. (b) Chromosomes obtained by the polyamine method show both three-dimensional profile and higher level folding of chromatin fibers, supporting the loop chromosome organization previously suggested by scanning electron microscopy observation of hexylene glycol isolated chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00362283
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    DNA synthesis progression in 3T3 synchronized fibroblasts: a high resolution approach (1992)
    Springer
    Histochemistry and cell biology 97 (1992), S. 181-187 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to investigate at ultrastructural level the mechanism of DNA synthesis progression during the different moments of S-phase a bromodeoxyuridine-anti bromodeoxyuridine (BrdU-anti BrdU) method has been applied to synchronized 3T3 fibroblasts. After 30 min BrdU incorporation, five different labelling patterns can be identified and should be related to early, middle and late S-phase. These patterns are represented mainly by diffuse labelling localized in different nuclear domains and by quite rare cases in which the labelling is limited to isolated clusters of gold particles. After a 5-min pulse with BrdU it is possible to observe isolated clusters of gold particles at each moment of S-phase, which, however, exhibit the same distribution of the five principal labelling patterns observed after 30 min incorporation. In both cases labelling can be detected in the interchromatin regions during early S-phase, at the boundary between interchromatin and heterochromatin during middle S-phase and in the heterochromatin domains during late S-phase. Considering their size, the isolated spots of labelling could be interpreted as single replication units which are subsequently activated throughout the different moments of the S-phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00267309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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