Cytochemical investigation of dynamics of RNA synthesis demonstrated in metaphase chromosomes of HeLa cells

1975 ◽  
Vol 79 (3) ◽  
pp. 315-317
Author(s):  
A. A. Kucheryavenko
Keyword(s):  
Hela Cells ◽  
Rna Synthesis ◽  
Metaphase Chromosomes ◽  
Cytochemical Investigation

Essential factors in the kinetic analysis of RNA synthesis in HeLa cells

1977 ◽  
Vol 90 (3) ◽  
pp. 521-534 ◽  
Author(s):  
Larry Puckett ◽  
James E. Darnell
Keyword(s):  
Kinetic Analysis ◽  
Hela Cells ◽  
Rna Synthesis

scholarly journals AN ANALYSIS OF HETEROCHROMATIN IN MAIZE ROOT TIPS

1967 ◽  
Vol 35 (1) ◽  
pp. 175-181 ◽  
Author(s):  
Marion Himes
Keyword(s):  
Rna Synthesis ◽  
Root Meristem ◽  
Tritiated Thymidine ◽  
B Chromosomes ◽  
Root Tips ◽  
Metaphase Chromosomes ◽  
Nonhistone Protein ◽  
Normal Maize ◽  
Definition Of ◽  
Nucleolar Rna

The B chromosomes of maize are condensed in appearance during interphase and are relatively inert genetically; therefore they fulfill the definition of heterochromatin. This heterochromatin was studied in root meristem cells by radioautography following administration of tritiated thymidine and cytidine, and was found to behave in a characteristic way, i.e. it showed asynchronous DNA synthesis and very low, if any, RNA synthesis. A cytochemical comparison of normal maize nuclei with nuclei from isogenic maize stock containing approximately 15–20 B-chromosomes in addition to the normal complement has revealed the following: (a) the DNA and histone contents are greater in nuclei with B chromosomes; (b) the proportion of DNA to histone is identical with that of nuclei containing only normal chromosomes; (c) the amount of nonhistone protein in proportion to DNA in interphase is less in nuclei with B chromosomes than in normal nuclei. In condensed B chromosomes the ratio of nonhistone protein to DNA is similar to that in other condensed chromatin, such as metaphase chromosomes and degenerating nuclei. The B chromosomes appear to have no effect on nucleolar RNA and protein. Replication of B chromosomes is precisely controlled and is comparable to that of the ordinary chromosomes not only in synthesis for mitosis but also in formation of polyploid nuclei of root cap and protoxylem cells.

scholarly journals An Authentic 3′ Noncoding Region Is Necessary for Efficient Poliovirus Replication

2005 ◽  
Vol 79 (18) ◽  
pp. 11962-11973 ◽  
Author(s):  
David M. Brown ◽  
Christopher T. Cornell ◽  
Genevieve P. Tran ◽  
Joseph H. C. Nguyen ◽  
Bert L. Semler
Keyword(s):  
Hela Cells ◽  
Deletion Mutant ◽  
Rna Synthesis ◽  
Rna Replication ◽  
Deletion Mutation ◽  
Noncoding Region ◽  
Compensatory Mutation ◽  
Genomic Rnas ◽  
Negative Strand ◽  
Rna Transfection

ABSTRACT Picornavirus RNA replication involves the specific synthesis of negative-strand intermediates followed by an accumulation of positive-strand viral RNA in the presence of a multitude of cellular mRNAs. Previously, in an effort to identify cis-acting elements required for initiation of negative-strand RNA synthesis, we deleted the entire 3′ noncoding regions from human rhinovirus and poliovirus genomic RNAs. These deletion mutation transcripts displayed a severe delay in RNA accumulation following transfection of HeLa cells. Interestingly, in subsequent infection of HeLa cells, the deletion-mutant poliovirus displayed only a moderate deficiency in RNA synthesis. These data suggested that the delay in the production of cytopathic effects after transfection may have been due to an RNA replication defect overcome by the accumulation of a compensatory mutation(s) generated during initial rounds of RNA synthesis. In this study, we have sequenced the entire genome of the deletion-mutant virus and found only two nucleotide changes from the parental clone. Transfection analysis of these sequence variants revealed that the sequence changes did not provide compensatory functions for the 3′ noncoding region deletion mutation replication defect. Further examination of the deletion mutant phenotype revealed that the severe replication defect following RNA transfection is due, in part, to nonviral terminal sequences present in the in vitro-derived deletion mutation transcripts. Our data suggest that poliovirus RNA harboring a complete 3′ noncoding region deletion mutation is infectious (not merely quasi-infectious).

scholarly journals PROPHASING OF INTERPHASE NUCLEI AND INDUCTION OF NUCLEAR ENVELOPES AROUND METAPHASE CHROMOSOMES IN HELA AND CHINESE HAMSTER HOMO- AND HETEROKARYONS

1974 ◽  
Vol 62 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Yoshitaka Obara ◽  
Lee S. Chai ◽  
Herbert Weinfeld ◽  
Avery A. Sandberg
Keyword(s):  
Nuclear Envelope ◽  
Hela Cells ◽  
Interphase Nucleus ◽  
Chinese Hamster ◽  
Binucleate Cell ◽  
Metaphase Chromosomes ◽  
Interphase Nuclei ◽  
Multinucleate Cells ◽  
Interphase Cells ◽  
Nuclear Envelope Formation

Fusing human HeLa metaphase cells with HeLa interphase cells resulted within 30 min in either of two phenomena in the resultant binucleate cell: either prophasing of the interphase nucleus or formation of a normal-appearing nuclear envelope around the metaphase chromosomes. The frequency of either occurrence was strongly dependent on environmental pH. At pH's of 6.6–8.0, prophasing predominated; at pH 8.5 nuclear envelope formation predominated. Additionally, the frequencies of the two events in multinucleate cells depended on the metaphase/interphase ratio. When the ratio was 0.33 nuclear envelope formation predominated; when it was 2.0 prophasing predominated. In their general features, the results with fused HeLa cells resembled those reported earlier with fused Chinese hamster Don cells. However, the results provided an indication that between pH 6.6 and 8.0 the HeLa metaphase cells possessed a much greater capacity than the Don metaphase cells to induce prophasing. Fusion of Don metaphase cells with HeLa interphase cells or of Don interphase cells with HeLa metaphase cells at pH 8.0 resulted in nuclear envelope formation or prophasing in each kind of heterokaryon. As in the homokaryons, the frequencies of the two events in the heterokaryons depended on the metaphase/interphase ratio. The statistics of prophasing and nuclear envelope formation in the homo- and heterokaryon populations were consistent with the notion that disruption or formation of the nuclear envelope depends on the balance attained between disruptive and formative processes.

Effects of vinblastine, podophyllotoxin and nocodazole on mitotic spindles. Implications for the role of microtubule dynamics in mitosis

1992 ◽  
Vol 102 (3) ◽  
pp. 401-416 ◽  
Author(s):  
M.A. Jordan ◽  
D. Thrower ◽  
L. Wilson
Keyword(s):  
Hela Cells ◽  
Mitotic Arrest ◽  
Mitotic Spindles ◽  
Microtubule Depolymerization ◽  
Metaphase Chromosomes ◽  
Low Concentrations ◽  
Subtle Effect ◽  
Full Complement ◽  
Spindle Microtubules

Inhibition of mitosis by many drugs that bind to tubulin has been attributed to depolymerization of microtubules. However, we found previously that low concentrations of vinblastine and vincristine blocked mitosis in HeLa cells with little or no depolymerization of spindle microtubules, and spindles appeared morphologically normal or nearly normal. In the present study, we characterized the effects of vinblastine, podophyllotoxin and nocodazole over broad concentration ranges on mitotic spindle organization in HeLa cells. These three drugs are known to affect the dynamics of microtubule polymerization in vitro and to depolymerize microtubules in cells. We wanted to probe further whether mitotic inhibition by these drugs is brought about by a more subtle effect on the microtubules than net microtubule depolymerization. We compared the effects of vinblastine, podophyllotoxin and nocodazole on the organization of spindle microtubules, chromosomes and centrosomes, and on the total mass of microtubules. Spindle organization was examined by immunofluorescence microscopy, and microtubule polymer mass was assayed on isolated cytoskeletons by a quantitative enzyme-linked immunoadsorbence assay for tubulin. As the drug concentration was increased, the organization of mitotic spindles changed in the same way with all three drugs. The changes were associated with mitotic arrest, but were not necessarily accompanied by net microtubule depolymerization. With podophyllotoxin, mitotic arrest was accompanied by microtubule depolymerization. In contrast, with vinblastine and nocodazole, mitotic arrest occurred in the presence of a full complement of spindle microtubules. All three drugs induced a nearly identical rearrangement of spindle microtubules, an increasingly aberrant organization of metaphase chromosomes, and fragmentation of centrosomes. The data suggest that these anti-mitotic drugs block mitosis primarily by inhibiting the dynamics of spindle microtubules rather than by simply depolymerizing the microtubules.

Studies on the Control of Ribosomal RNA Synthesis in HeLa Cells

1975 ◽  
Vol 57 (1) ◽  
pp. 79-83 ◽  
Author(s):  
C. James CHESTERTON ◽  
Barbara E. H. COUPAR ◽  
Peter H. W. BUTTER WORTH ◽  
Janice BUSS ◽  
Melvin H. GREEN
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis

RNA synthesis in permeable HeLa cells

1980 ◽  
Vol 201 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Robert Wydro ◽  
Nathan Brot ◽  
Herbert Weissbach
Keyword(s):  
Hela Cells ◽  
Rna Synthesis
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