Effects of cordycepin on morphology and RNA synthesis of amphibian lampbrush chromosomes

Actinomycin D inhibits RNA synthesis on the lateral loops of newt lampbrush chromsomes. Partial inhibition does not provoke marked morphological alteration of ordinary lateral loops, most of which recover to the full their capacity for RNA synthesis within 2 days of treatment. However, occasional ordinary loops do not recover completely within the first few days after treatment, and in such loops RNA-synthesizing capacity is restricted to a region adjoining the thinner insertion in the parent chromomere. A greater degree of inhibition of RNA synthesis is accompanied by loss of matrix from ordinary lateral loops, and in the extreme case the loop axes retract to their parent chromomeres and neighbouring chromomeres coalesce; for the ordinary loops, full recovery from this stripped condition is nevertheless possible. Some 20 µ per loop extends during the first day following exposure to actinomycin, and normal morphology and RNA-synthesizing capacity are regained within 2-4 days. The giant granular loop of Triturus cristatus cristatus chromosome XII responds to extreme actinomycin D poisoning in different fashion. Matrix does not at once slough off its loop axis, but the loop present at the time of treatment is progressively replaced by a new granular loop which develops between the parent chromomere and the original loop's dense tip. These observations support the theory that the DNA-containing axes of all lateral loops of lampbrush chromosomes continually extend from their parent chromomeres, engage in RNA synthesis while extended, and carry the associated RNP matrix along as they move towards the return insertions in the parent chromomeres, where loop axis retraction occurs.

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Relationship between RNA Synthesis and Loop Structure in Lampbrush Chromosomes

Science ◽

10.1126/science.140.3565.382-b ◽

1963 ◽

Vol 140 (3565) ◽

pp. 382-382

Author(s):

M. Izawa ◽

V. G. Allfrey ◽

A. E. Mirsky

Keyword(s):

Rna Synthesis ◽

Loop Structure ◽

Lampbrush Chromosomes

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Lampbrush chromosomes and RNA-synthesis during early oogenesis of Brachydanio rerio (cyprinidae, teleostei)

Cell and Tissue Research ◽

10.1007/bf00307195 ◽

1973 ◽

Vol 145 (1) ◽

pp. 145-150 ◽

Cited By ~ 8

Author(s):

Horst Gerhard Baumeister

Keyword(s):

Rna Synthesis ◽

Lampbrush Chromosomes ◽

Brachydanio Rerio

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THE RELATIONSHIP BETWEEN RNA SYNTHESIS AND LOOP STRUCTURE IN LAMPBRUSH CHROMOSOMES

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.49.4.544 ◽

1963 ◽

Vol 49 (4) ◽

pp. 544-551 ◽

Cited By ~ 82

Author(s):

M. Izawa ◽

V. G. Allfrey ◽

A. E. Mirsky

Keyword(s):

Rna Synthesis ◽

Loop Structure ◽

Lampbrush Chromosomes ◽

The Relationship

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Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066796 ◽

1971 ◽

Vol 29 ◽

pp. 548-549

Author(s):

Awtar Krishan ◽

Dora Hsu

Keyword(s):

Granular Material ◽

Rna Synthesis ◽

Culture Medium ◽

Actinomycin D ◽

Metabolic Inhibitors ◽

Protein And Rna Synthesis ◽

Apparent Reduction ◽

Plant Alkaloids ◽

In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

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Protein Synthesis DNA Synthesis and Repair RNA Synthesis Energy-Linked ATPases Synthetases

10.1016/s1874-6047(08)x6008-1 ◽

1974 ◽

Keyword(s):

Protein Synthesis ◽

Dna Synthesis ◽

Rna Synthesis

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THE NUCLEAR RNA-SYNTHESIS IN THE ANTERIOR PITUITARY OF RATS

Acta Endocrinologica ◽

10.1530/acta.0.049s160 ◽

1965 ◽

Vol 49 (3_Suppl) ◽

pp. S160 ◽

Cited By ~ 2

Author(s):

E. Stöcker ◽

G. Dhom

Keyword(s):

Anterior Pituitary ◽

Rna Synthesis ◽

Nuclear Rna Synthesis ◽

Nuclear Rna

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FEMALE ENDOCRINE CONTROL MECHANISMS DURING THE NEONATAL PERIOD

Acta Endocrinologica ◽

10.1530/acta.0.0700396 ◽

1972 ◽

Vol 70 (2) ◽

pp. 396-408 ◽

Cited By ~ 1

Author(s):

K.-D. Schulz ◽

H. Haarmann ◽

A. Harland

Keyword(s):

Protein Synthesis ◽

Reproductive System ◽

Rna Synthesis ◽

Neonatal Period ◽

High Dose ◽

Female Reproductive System ◽

Endocrine Control ◽

Hypothalamic Region ◽

Rna And Protein Synthesis ◽

Physiological Dose

ABSTRACT The present investigation deals with the oestrogen-sensitivity of the female reproductive system during the neonatal period. Newborn female guinea pigs were used as test animals. At different times after a single subcutaneous injection of a physiological dose of 0.1 μg or an unphysiologically high dose of 10 μg 17β-oestradiol/100 g body weight, the RNA- and protein-synthesis was examined in the hypothalamic region, pituitary, cerebral cortex, liver, adrenal gland, ovary and uterus. With a physiological dose an increase in organ weight, protein content, RNA-and protein-synthesis was found only in the uterus. These alterations turned out to be dose-dependent. In addition to the findings in the uterus an inhibition of the aminoacid incorporation rate occurred in the liver following the injection of the high oestradiol dose. As early as 1 hour after the administration of 0.1 μg 17β-oestradiol an almost 100% increase in uterine protein synthesis was detectable. This result demonstrates a high oestrogen-sensitivity of this organ during the neonatal period. All the other organs of the female reproductive system such as the hypothalamus, pituitary and ovary did not show any oestrogen response. Therefore the functional immaturity of the uterus during post partem life is not the result of a deficient hormone sensitivity but is correlated with the absence of a sufficient hormonal stimulus at this time. The investigation on the effects of actinomycin resulted in different reactions in the uterus and liver. In contrast to the liver a paradoxical actinomycin effect was found in the uterus after treatment with actinomycin alone. This effect is characterized by a small inhibition of RNA-synthesis and a 50% increase in protein synthesis. The treatment of the newborn test animals with actinomycin and 17β-oestradiol together abolished the oestrogen-induced stimulation of the uterine RNA-and protein-synthesis. Consequently, the effect of oestrogens during the neonatal period is also connected with the formation of new proteins via an increased DNA-directed RNA-synthesis.

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