An Electron Microscope Study of Lampbrush Chromosomes
نویسندگان
چکیده
منابع مشابه
An Electron Microscope Study of Lampbrush Chromosomes
Lampbrush chromosomes were isolated from germinal vesicles of oocytes from Necturus maculatus, Triturus viridescens, Pseudotriton montanus and Rana pipiens. After treatment of isolated nuclei with 10 per cent sucrose, chromosomes free of nuclear sap are obtained for examination in either the light microscope or in the electron microscope. For electron microscopy the chromosomes were prepared ei...
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HE limitation in the penetrating power of electrons is one of the most T serious obstacles in the study of chromosomes by electron microscopy. Chromosomes are generally larger than 0.2p in diameter and are nearly opaque to electron penetration. At various stages of the nuclear cycle, however, chromosomes change their size and shape. Dividing chromosomes are generally largest and “resting” chrom...
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The morphology of the DNP axis and RNP transcripts from Xenopus laevis lampbrush chromosomes has been analysed using a modified Miller spreading technique. Two basictypes of chromatin have been distinguished. (1) Discrete portions of DNP exhibiting high levels of transcriptive activity, with clear initiation and termination points (transcription units). Interspersed with the units are sequences...
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Amphibian lampbrush chromosomes and meiotic prophase chromosomes of various insects and plants consist of a bundle of microfibrils about 500 A thick. These fibrils are double, being made of two closely associated fibrils 200 A thick. Fragments of interphase nuclei contain a mass of fibrils 200 A thick. Ultrathin sections through nuclei in prophase or interphase show sections of these double or ...
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A method is described by which single mitotic cells growing in tissue culture can be selected under the light microscope and then sectioned for electron-microscopic study. The method has been applied to mitotic cells in newt heart cultures and to monolayer cultures of human fibroblasts. The structure of the chromosomes and of the mitotic apparatus at various phases of mitosis are described and ...
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ژورنال
عنوان ژورنال: The Journal of Biophysical and Biochemical Cytology
سال: 1958
ISSN: 1540-8140,0021-9525
DOI: 10.1083/jcb.4.1.99