Germination of Rye Embryos Following Hydration-Dehydration Treatments: Enhancement of Protein and RNA Synthesis and Earlier Induction of DNA Replication

1974 ◽  
Vol 25 (6) ◽  
pp. 1010-1019 ◽  
Author(s):  
SWATI SEN ◽  
DAPHNE J. OSBORNE
Author(s):  
Awtar Krishan ◽  
Dora Hsu

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).


2000 ◽  
Vol 257 (1) ◽  
pp. 152-161 ◽  
Author(s):  
Katerina Vareli ◽  
Maria Frangou-Lazaridis ◽  
Ineke van der Kraan ◽  
Orestes Tsolas ◽  
Roel van Driel

1981 ◽  
Vol 47 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Saburo Omata ◽  
Hidemi Tsubaki ◽  
Kenji Sakimura ◽  
Mitsuru Sato ◽  
Ryuji Yoshimura ◽  
...  

PEDIATRICS ◽  
1978 ◽  
Vol 62 (6) ◽  
pp. 1143-1150
Author(s):  
Arthur F. Kohrman

The use of the fetal and neonatal mouse to study the effects of steroidal and nonsteroidal substances on development and carcinogenesis has a long history. Since the early 1960s, this animal model system has been exploited by several groups throughout the world, and it is useful to recount some of the more significant points in this history. I shall also point out areas of inquiry where the mouse model continues to be used in a search for the fundamental nature of the processes by which steroid hormones cause permanent effects during development, with the hope that some of those experiments may provide clues to the causes of present or yet unseen situations in the human. Early studies1,2 showed vaginal and cervical tumor formation in adult mice treated with estrogens in the newborn period. As early as 1963, concern was expressed about the possibility of similar consequences in humans who might be exposed to hormonal substances early in development. Subsequent investigations2-4 showed that administration of estrogen and androgen to newborn female mice in the first five days of life led to permanent vaginal and cervical changes in the adult, which were in many cases (depending on the dose administered) ovary independent; that is, the changes persisted after ovariectomy of the animal at day 40. Studies on the vaginal tissues of the adult animals that had been treated with steroids in the newborn period showed that there were permanent alterations of rates of DNA, protein, and RNA synthesis in those tissues, and that those changes apparently occurred with out modification of the fundamental characteristic of specific binding of estrogen by the vagina.3


1969 ◽  
Vol 24 (12) ◽  
pp. 1624-1629 ◽  
Author(s):  
Günter Cleffmann

Actinomycin in low concentration (0,2 μg/ml — 0,5 μg/ml) prolongs the average duration of the cell cycle of Tetrahymena considerably, but does not inhibit cell division completely. Some parameters of the growing cell have been tested in cell cycles extended in this way and compared to those of normally growing cells. The RNA synthesis of treated cells is reduced to such an extent that the RNA content per cell decreases during the prolonged cell cycle. Nevertheless cell growth, protein synthesis and DNA replication proceed at almost the same rate as in untreated cells. These findings indicate that the presence of actinomycin does not interfere with RNA fractions necessary for growth but reduce the synthesis of RNA fractions which are essential for cell division. Therefore a longer period is needed for their accumulation.


1981 ◽  
Vol 36 (11-12) ◽  
pp. 942-950 ◽  
Author(s):  
Peter Westhoff ◽  
Kurt Zimmermann ◽  
Frank Boege ◽  
Klaus Zetsche

Abstract Transfer of heterotrophically grown cells of the unicellular green alga Chlorogonium elongatum to autotrophic growth conditions causes a 10 -15 fold increase in the amount of the chloroplastic enzyme ribulose-1,5-bisphosphate carboxylase. This increase was found to be due to de novo synthesis. The relative proportions of large and small subunits of the enzyme do not change. Their ratio is close to 3.4, the proportions in weight of the two subunits in the holoenzyme. Continous labelling with [35S]sulfate reveals that the ratios of incorporation into large and small subunits are essentially the same in autotrophic and heterotrophic cells. Pulse-chase experiments show that the subunits are degraded synchronously. The coordinated subunit synthesis cannot be uncoupled using inhibitors of protein and RNA synthesis or high temperature of cultivation of the alga. The results suggests a very tightly coordinated synthesis of the large and small subunits of ribulosebisphosphate carboxylase.


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