Polyribosomes from Peas

Davies, Eric

doi:10.1104/pp.52.4.339

Cited by 38 publications

(27 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alaska were decapitated and treated with lanolin for 2 to 3 days in order to age the tissue (1). After this aging period, excess lanolin was wiped off, a mark was made 10 mm below the apex to delineate a "segment" of tissue, and the apex was coated with fresh lanolin with or without additives.…”

Section: Methodsmentioning

confidence: 99%

“…We suggested that the hormone was acting to cause either synthesis or activation of mRNA to which existing ribosomes could attach (1). In a later paper (4), however, we showed that only a selected sample of polysomes had been analyzed for the data on polysome metabolism; the membrane-bound polysomes had been discarded entirely and only 30% of the FP1 had been analyzed.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Polyribosomes from Peas

Davies

1976

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Auxin treatment of aged pea stems (Pisum sativum L. var. Alaska) caused a decrease in monosomes (especially free monosomes) and an increase in polysomes (especially membraae-bound polysomes). These effects were not duplicated by gibberellic acid or benzyladenine. These auxin-stimulated shifts in polysome distribution commenced at least 9 hours before significant growth took place. It is suggested that this auxinstimulated incorporation of free monosomes into membrane-bound polysomes might involve increased utilization (through activation or synthesis) of messenger RNA(s) acting as template(s) for synthesis of secretable enzyme(s) involved in growth.Lincoln, Nebraska 68508 supematant, containing free polysomes, was layered directly on to gradients, the pellet containing MBP was resuspended in buffer A containing 2% (v/v) Triton X-100 prior to layering.The gradients, usually 125 to 500 mg/ml sucrose in buffer B (20 mM tris-HCl, pH 8.5; 20 mm KCI; 10 mM MgCI2), were centrifuged in a Spinco SW-36 rotor at 34,000 rpm for 75 min (MBP) or 125 min (FP). All operations were conducted at 2 C.The contents of the gradient tubes were monitored on an ISCO Model 640 gradient fractionator, and the A254 was monitored continuously. The areas under the regions: monosomes (M), small polysomes containing two to five ribosomes (SP), large polysomes containing more than five ribosomes (LP) were measured by planimetry.In an earlier paper (1), we showed that IAA elicited a 2-fold increase in the mRNA content of free polysomes within 6 hr of its application to aged pea epicotyls. We suggested that the hormone was acting to cause either synthesis or activation of mRNA to which existing ribosomes could attach (1). In a later paper (4), however, we showed that only a selected sample of polysomes had been analyzed for the data on polysome metabolism; the membrane-bound polysomes had been discarded entirely and only 30% of the FP1 had been analyzed. This suggested an alternative explanation for the auxin-stimulated increase in free polysomes, i.e. pre-existing polysomes could have been released from membranes. To test this possibility, the experiments reported here were conducted to find out whether IAA had any effect on membrane-bound polysomes, and also to find out whether similar responses could be elicited by other hormones. MATERIALS AND METHODSDark-grown seedlings of Pisum sativum L. var. Alaska were decapitated and treated with lanolin for 2 to 3 days in order to age the tissue (1). After this aging period, excess lanolin was wiped off, a mark was made 10 mm below the apex to delineate a "segment" of tissue, and the apex was coated with fresh lanolin with or without additives. The plants continued to grow in the dark until harvested for polyribosome isolation.Polysomes were isolated as described earlier (4). Usually 50 segments were homogenized in 5 ml of buffer A (0.25 M sucrose; 0.2 M tris-HCl, pH 8.5; 60 mm KCI; 30 mm MgCl2). The brei was squeezed through nylon cloth, and the liquid was centrifuged at 5OOg for 10 min. The p...

show abstract

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Polyribosomes from Peas

Davies

1976

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although there is only a slight increase in the total amount of ribosomal material, the amount of mRNA doubles in the free polysomes within 6 h of hormone treatment (4). Figure 1 shows the effect of IAA on the poly(A) content per segment within the free polysomes, membrane-bound polysomes, and the postribosomal supernatant.…”

mentioning

confidence: 99%

“…6a) will be considered first. Of the 58 products which decreased in intensity during aging (15) 4. Total RNA extracted from hormone-treated tissue evokes the synthesis of polypeptides different from those synthesized by RNA from control tissue.…”

mentioning

confidence: 99%

Ribonucleic Acid and Protein Metabolism in Pea Epicotyls

Schuster¹,

Davies²

1983

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Applications of auxin to the tips of intact aged pea Pisum sativaum L. var Alaska epicotyls resulted in an increase in the content of polyribosomes and poly(A) and in the capacity of isolated polysomes to support protein synthesis in vitro. Few changes were seen in the two-dimensional gel patterns of silver-stained proteins accumulated (or degrded) in vivo even after 15 hours of auxin treatment. In contrast, substantial changes were evident in the two-dimensional gel fluorographs of polypeptides generated in vitro by total RNA and by polysomal RNA from tissue treated with auxin for only 6 hours. Of the 200 spots resolved by fluorography, total RNA from auxin-treated tissue generated 33 spots with increased intensity and 10 with decreased intensity; polysomal RNA yielded 33 spots which increased and only three that decreased. In general, the polypeptides that increased in intensity were higher molecular weight and those that decreased were lower molecular weight. These changes occurred prior to growth and might be prerequisite for the auxininduced slow growth response seen in this aged tissue.Comparisons were made between the changes in RNA and protein metabolism occuring during aging and after wounding and auxin treatment of aged tissue. Aging causes a decline in poly(A), polysomes, and protein synthesizing capacity, whereas wounding and auxin treatment cause increases. Wounding appears to act primarily at the level of translation, whereas auxin has a greater effect on transcription. It is argued that the use of excised tissue to study auxin effects on RNA and protein metabolism should be avoided.A tremendous amount of evidence had accumulated until the late 1960s to support the contention that RNA and protein synthesis were required for auxin to induce growth in a wide variety of tissues (8). However, at about that time fast growth responses to auxin were discovered and it was argued that these responses to auxin were too fast to involve RNA synthesis (6). For the next 10 years, the fast growth theory, and its compatriot, the acid growth theory, held sway (14). A decade later, Vanderhoef (18 and references therein) postulated that auxin evokes two responses, one rapid but short-lived, for which RNA and protein synthesis may not be required, the other slower to develop but of greater duration for which RNA and protein synthesis are required.

show abstract

“…Such changes are interpreted as a change in the translational capacity of the tissue, which may be part of the molecular mechanism utilized by plant cells to modulate their rate of growth (see, e.g., Beevers & Poulson, 1972;Davies & Larkins, 1972;Fountain & Bewley, 1973;Verma & Marcus, 1974;Travis et al, 1973).…”

mentioning

confidence: 99%