X-irradiation Effects on Protein Synthesis and Synthesis of Messenger Ribonucleic Acid from Peanut Cotyledons

Exposure of peanut seed to 500 kr of x-rays followed by 6 weeks of storage before planting resulted in a severe reduction of 14 C-amino acid incorporation by the ribosomal material. Ribosomes from irradiated tissue were just as effective as those from control tissue in amino acid incorporation direc...

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Bibliographic Details
Published in:The Journal of biological chemistry 1968-05, Vol.243 (9), p.2315-2320
Main Authors: Van Huystee, R B, Jachymczyk, W, Tester, C F, Cherry, J H
Format: Article
Language:English
Subjects:
Amino Acids - metabolism
Carbon Isotopes
Centrifugation, Density Gradient
Chromatography
DNA
Leucine - metabolism
Phenylalanine - metabolism
Phosphorus Isotopes
Plants - radiation effects
Polynucleotides
Protein Biosynthesis
Radiation Effects
Ribonucleases - metabolism
Ribosomes - metabolism
Ribosomes - radiation effects
RNA, Messenger - biosynthesis
RNA, Transfer - biosynthesis
Space life sciences
Uracil Nucleotides
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Summary:Exposure of peanut seed to 500 kr of x-rays followed by 6 weeks of storage before planting resulted in a severe reduction of 14 C-amino acid incorporation by the ribosomal material. Ribosomes from irradiated tissue were just as effective as those from control tissue in amino acid incorporation directed by exogenous messenger ribonucleic acid and polyuridylic acid. Polyribosomes were nearly absent from the ribosomal material obtained from irradiated tissue, and the synthesis of RNA and protein in vivo was much less than that for control cotyledons. The 105,000 x g supernatant from irradiated tissue was superior to the control supernatant when control ribosomes were used, but gave the same activity with ribosomes from irradiated tissue. Assay of leucyl and phenylalanyl transfer RNA synthetases showed that x-irradiation does not affect their activities. The supernatant fraction from irradiated tissue contains, however, only one-third as much ribonuclease activity as that of the control. The high level of RNase activity in the control 105,000 x g supernatant possibly leads to degradation of the template and ribosomal RNAs, thereby reducing amino acid incorporation. Other experiments showed that mRNA, purified by methylated albumin Kieselguhr column chromatography from irradiated tissue, hybridized with control DNA about 20% as well as that from control tissue. It is concluded from our results that x-irradiation reduces the capacity of cells to produce biologically functional mRNA.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)93477-0