Growth promoters and the synthesis of protein in plant mitochondria: Part I — Effect of kinetin on the incorporation of amino acids into mitochondrial protein
06 Jun 1969-Biochemical and Biophysical Research Communications (Academic Press)-Vol. 35, Iss: 5, pp 606-610
TL;DR: Kinetin stimulates protein synthesis in mitochondria isolated from 48-hr etiolated seedlings of Vigna sinensis (Linn.) Savi and shows a synergistic effect with indole-3-acetic acid in regard to amino acid incorporation.
About: This article is published in Biochemical and Biophysical Research Communications.The article was published on 1969-06-06. It has received 15 citations till now. The article focuses on the topics: Kinetin & Amino acid.
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TL;DR: By measuring the differences of the specific radioactivities of the polysomes the following results were revealed: 1) Kinetin increases the protein synthesis by an average of 35%-2) Auxin has no effect on protein synthesis.
Abstract: The influence of naphthalene-1-acetic acid and kinetin on protein synthesis in vivo was investigated by measuring the incorporation of radioactive amino acids into polypeptides of synthesizing polysomes. The second subculture of sterile pith tissue of Nicotiana tabacum L. cv. Wisconsin 38 grown on a medium containing only a minimum of growth substances was further starved in a small volume of medium lacking auxin and cytokinin for 12 h. An incubation period of 4 h with [14C]amino acids followed. The last 30 min of those incubations were carried out in the presence of actinomycin D and the last 20 min were performed under different conditions: a) without any growth substances, b) with naphthalene-l-acetic acid, c) with kinetin. By measuring the differences of the specific radioactivities of the polysomes the following results were revealed: 1) Kinetin increases the protein synthesis by an average of 35%-2) Auxin has no effect on protein synthesis.
25 citations
01 Jan 1972
TL;DR: The rapidity of the response to cytokinin in plastids and mitochondria (lag period only a few minutes) suggests that the hormone may promote protein synthesis in a direct way, possibly by interaction with the ribosome.
Abstract: Considerable experimental evidence supports the view that phytohormones affect transcription (see Letham, 1969). However certain other observations suggest that cytokinins may also modify transiational processes. For example cytokinins maintain the level of ribosomes in excised leaf tissue (Shaw and Manocha, 1965; Srivastava and Arglebe, 1968; Berridge and Ralph, 1969). Although the conclusion that cytokinins promote protein synthesis in excised leaf tissue undergoing senescence (Osborne, 1962) no longer seems valid (see Tavares and Kende, 1970; Kuraishi, 1968), cytokinins markedly increase the specific activity of protein in purified nuclei, mitochondria and plastids incubated with labelled amino acids in vitro (Datta and Sen, 1965; Bhattacharyya and Roy, 1969; Davies and Cocking, 1967). The rapidity of the response to cytokinin in plastids and mitochondria (lag period only a few minutes) suggests that the hormone may promote protein synthesis in a direct way, possibly by interaction with the ribosome.
16 citations
TL;DR: The purine derivatives, adenine and N6-methyl-aminopurine, which exhibit low cytokinin activity overcame the inhibitory effects of Kinetin and Ribosomal RNA was the first RNA species affected by kinetin.
Abstract: The rate of 14C-leucine and 3H-uracil incorporation by tobacco cells (Nicotiana tabaccum var. Samsun N.N.) in suspension culture was simultaneously decreased by the addition of kinetin at concentrations above 2.5 × 10−5m. Ribosomal RNA was the first RNA species affected by kinetin. The purine derivatives, adenine and N6-methyl-aminopurine, which exhibit low cytokinin activity overcame the inhibitory effects of kinetin. However, purine derivatives without cytokinin activity, guanine, N6,6-dimethyl-aminopurine, and 2-aminopurine, did not relieve kinetin inhibition.
10 citations
01 Jan 1977
TL;DR: It has been shown that cytokinins possess an affinity site within the cell membrane of Achlya, related to Ca2+-, amino acid- and auxin-transport and an affinity sites on the ribosomes of higher plants, which influence protein synthesis in vivo and in vitro.
Abstract: Cell metabolism is regulated by cell membrane functions due to the control of influx and efflux of the different molecules and ions found in cells. Cell metabolism depends also essentially on gene activation and protein synthesis. It has been shown that cytokinins possess an affinity site within the cell membrane of Achlya, related to Ca2+-, amino acid- and auxin-transport (18) and an affinity site on the ribosomes of higher plants (5). Moreover cytokinins influence protein synthesis in vivo (7, 16, 30) and in vitro (17). Cytokinins also influence in vitro protein synthesis in systems prepared from Lactobacillus acidophilus and wheat germ. Affinity chromatography of extracts of maize shoots (10) and wheat germ on N6-(Δ2-isopentenyl) adenosine-sepharose 6B results in four different cytokinin-binding proteins. Structures and functions of these proteins have to be analyzed.
10 citations
TL;DR: While auxins exert their influence on the RNA transcription, cytokinins may possibly influence the translation process, according to the following working hypothesis.
Abstract: The influence of auxin and cytokinin on RNA synthesis was investigated by measuring (32)PO4 (3-)-incorporation into polysomes and polysomal RNAs of tissue grown from pith of Nicotiana tabacum L. The test tissue grown on a medium containing a minimum of auxin and cytokinin was further starved for a period of 12 h prior to the experiments. The tests were carried out under the following different conditions: 1. without any growth substances, 2. with auxin only, 3. with kinetin only, and 4. with auxin and kinetin. The tissues were incubated in small volumes of the test medium for 1-8 h on a shaker. The last hour of incubation was carried out in the presence of (32)PO4 (3-).Differences in (32)PO4 (3-) uptake into the polysomes were observed as early as after 3 h of incubation. Kinetin alone shows no effect at all, auxin causes increased synthesis of polysomal RNAs, and kinetin administered together with auxin augments the increase of (32)PO4 (3-) uptake into polysomes and polysomal RNAs observed with auxin alone. These results and those of Seth and Wareing [J. exp. Bot. 18, 65-77 (1967)], Bhattacharyya and Roy [Biochem. biophys. Res. Commun. 35, 606-610 (1969)], and Venis [Proc. nat. Acad. Sci. (Wash.) 68, 1824-1827 (1971)] lead to the following working hypothesis: while auxins exert their influence on the RNA transcription, cytokinins may possibly influence the translation process.
9 citations
References
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193 citations
TL;DR: The induced stimulation of nuclear RNA synthesis is abolished by actinomycin D but can be restored partially or completely by relatively higher concentrations of the growth substances.
52 citations
28 citations
TL;DR: Aluxin-induced stimulation of amino acid incorporation into protein of pea internodes is localised largely in the nucleus soon after auxin application, and can be restored considerably by higher concentrations of the growth substances.
21 citations
TL;DR: It is suggested that several kinins occur naturally in plants since kinetin and naturally occurring kinins were effective in maintaining the detached green leaves turgid and green but were ineffective in preserving the turgidity of the detached albino leaves; therefore, chloroplast are in some way involved in the response of detached leaves to kinins.
18 citations