The paper is composed of two parts : a review of a group of experiments among irradiated plants and own search for radiation hormesis in a single experiment. In the first part the Bayesian analysis of the hormetic-like data published so far shows that the NOAEL (no observed adverse effect level) point, above which adverse effects appear, may be located between 30 and 100 Gy. In the second part the influence of low doses of ionizing radiation was tested on the particularly fast growing plant, namely the cress (Lepidium sativum L.). Two experimental scenarios were used : in the first one the cress was irradiated during the growth (maximal dose 2.3 Gy), while in the second scenario dry seeds were irradiated (maximal dose 100 Gy). The experiment indicates that the NOAEL point lies above 100 Gy and statistically insignificant hormetic effect can be seen between 0.1 and 14 Gy. No linear reaction is observed in the full range of doses.
Cell ability to control amount of a transfer RNA is one of the ways to regulate rate of protein synthesis. Because 80–90% dry mass of cells are proteins, the level of translation is determinant to the cell growth. Growth of cells is a key question in tumors therapy and biotechnology. tRNA turnover consist of a three pathways described in a last few years: exosome and TRAMP complex dependent pathway in nucleus, directed to hypomodified or affected tRNA; rapid tRNA decay pathway involving two 5’–3’ exonucleases Rat1 and Xrn1, proposed to occur in nucleus and cytoplasm; stress-activated endonucleolytic cleavage to tRNA halves pathway, founded in cytoplasm with a clear role to direct regulation of translation by tRNA half-molecules inhibition.
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