Giant Chromosomes
Mostrando 13-24 de 24 artigos, teses e dissertações.
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13. In situ localization of DNA topoisomerase II, a major polypeptide component of the Drosophila nuclear matrix fraction.
DNA topoisomerase II has been immunochemically identified on protein blots as a major polypeptide component of the Drosophila nuclear matrix-pore complex-lamina fraction. Indirect immunofluorescence analyses of larval cryosections have confirmed the nuclear localization of topoisomerase II in situ. Although apparently excluded from the nucleolus, the topoiso
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14. Genetic instability in Drosophila melanogaster: deletion induction by insertion sequences.
Females of Drosophila melanogaster heteroallelic or homoallelic for X chromosome giant (gt) mutants generate deletions involving the wild-type alleles at two X chromosome gene loci: yellow body color (y) and white eye color (w). The deletions, bidirectional in the case of y and with fixed endpoint in the case of w, are associated with particular X chromosome
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15. A knob-associated tandem repeat in maize capable of forming fold-back DNA segments: Are chromosome knobs megatransposons?
A class of tandemly repeated DNA sequences (TR-1) of 350-bp unit length was isolated from the knob DNA of chromosome 9 of Zea mays L. Comparative fluorescence in situ hybridization revealed that TR-1 elements are also present in cytologically detectable knobs on other maize chromosomes in different proportions relative to the previously described 180-bp repe
The National Academy of Sciences.
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16. Experimental surgery to create subgenomes of Bacillus subtilis 168
The 4,188-kb circular genome of Bacillus subtilis 168 was artificially dissected into two stable circular chromosomes in vivo, one being the 3,878-kb main genome and the other the 310-kb subgenome that was recovered as covalently closed circular DNA in CsCl-ethidium bromide ultracentrifugation. The minimal requirements to physically separate the 310-kb DNA s
The National Academy of Sciences of the USA.
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17. Evidence for Transport of 75S RNA from a Discrete Chromosome Region via Nuclear Sap to Cytoplasm in Chironomus tentans
Salivary glands of the dipteran Chironomus tentans were exposed to tritiated pyrimidines for different time periods either in vitro or in vivo. Nonribosomal, high molecular weight RNA molecules of very different sizes (15-100 S) were labeled on chromosomes I-III, while only one main species, 75S RNA, was recorded in Balbiani ring 2, a giant chromosome puff o
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18. Chromosome puff activity and protein synthesis in larval salivary glands of Drosophila melanogaster.
Secretion proteins from larval salivary glands of Drosophila melanogaster were analyzed with acrylamide gel electrophoresis. Four fractions were found; three showed electrophoretic variants in different wild-type stocks. Crossbreeding and cytogenetic techniques were used to localize the genes responsible for the two main fractions: The gene for fraction 3 wa
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19. Molecular analysis of a steroid-induced regulatory hierarchy: the Drosophila E74A protein directly regulates L71-6 transcription.
Steroid hormones orchestrate the growth and development of higher organisms by directing spatially and temporally coordinated programs of gene expression. These changes in gene activity can be visualized in Drosophila by virtue of its giant salivary gland polytene chromosomes. A small set of early puffs are induced directly by the steroid hormone ecdysone. T
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20. Specific binding of Drosophila nuclear protein PEP (protein on ecdysone puffs) to hsp70 DNA and RNA.
The Drosophila protein PEP (protein on ecdysone puffs), a component hnRNP complexes, was previously immunocytologically localized on Drosophila giant chromosomes to puffs induced by ecdysone and to some heat shock-induced puffs (e.g. at the hsp70 locus at 87A7). Here, PEP was purified to homogeneity and characterized in its DNA and RNA binding features with
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21. A Novel Transvection Phenomenon Affecting the White Gene of Drosophila Melanogaster
The zeste(1) mutation of Drosophila melanogaster suppresses the expression of white genes in the eye. This suppression is normally dependent on there being two copies of w(+) located close to each other in the genome--they may either be in cis (as in a tandem duplication of w(+)) or in trans, i.e. on homologous chromosomes. Duplicated w(+) genes carried by a
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22. Fission yeast Cut1 and Cut2 are essential for sister chromatid separation, concentrate along the metaphase spindle and form large complexes.
Fission yeast Schizosaccharomyces pombe temperature-sensitive (ts) cut1 mutants fail to separate sister chromatids in anaphase but the cells continue to divide, leading to bisection of the undivided nucleus (the cut phenotype). If cytokinesis is blocked, replication continues, forming a giant nucleus with polyploid chromosomes. We show here that the phenotyp
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23. Characterization of Drosophila DNA-binding protein DB-2: demonstration of its sequence-specific interaction with DNA.
A DNA-binding protein (DB-2) was isolated from unfertilized Drosophila eggs by DNA-cellulose chromatogrphy. In competition assays with DNA from other species, DB-2 preferentially binds to Drosophila DNA. This binding protein can also be isolated from pupal nuclei and comprises only a small fraction ( < 0.01%) of the total nonhistone chromosomal proteins. In
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24. Assembly and transport of a premessenger RNP particle
Salivary gland cells in the larvae of the dipteran Chironomus tentans offer unique possibilities to visualize the assembly and nucleocytoplasmic transport of a specific transcription product. Each nucleus harbors four giant polytene chromosomes, whose transcription sites are expanded, or puffed. On chromosome IV, there are two puffs of exceptional size, Balb
The National Academy of Sciences.