Studies on rat reticulocyte polysomes during in vitro maturation

Trakatellis, Anthony C.; Heinle, Edward W.; Montjar, M.; Axelrod, A. E.; Jensen, Wallace N.

doi:10.1016/0003-9861(65)90014-7

Cited by 12 publications

(3 citation statements)

References 36 publications

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“…Using this criterion, a mean functional lifetime of 1 hr was obtained for divisionrelated mRNA's in irradiated cells. This value is in agreement with other estimates of the mean lifetime of mammalian mRNA (Villa-Trevion et al, 1964;Trakatellis et al, 1965 a;Trakatellis et al, 1965 b) and suggests that irradiating the cells does not affect the stability of mRNA. Thus, messengers synthesized at the time of irradiation (as established by simultaneous irradiation and actinomycin addition) are functional in coding for division proteins if the radiation-induced delay period following RNA inhibition is less than the lifetime of the messengers.…”

Section: Discussionsupporting

confidence: 92%

Radiosensitivity of Mammalian Cells

Walters¹,

Petersen²

1968

Biophysical Journal

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Radiation effects on macromolecular synthesis essential for the Chinese hamster cell to traverse the life cycle and to divide have been investigated. Life-cycle analysis techniques employing inhibitors of macromolecular synthesis were used in determining the kinetics of cell growth for specific segments of the population following spontaneous recovery from radiation-induced division delay. The results indicated that recovery does not occur in the absence of functional protein synthesis. Under conditions which inhibit normal RNA and DNA synthesis, irradiated cells can recover the capacity to traverse the life cycle and to divide. The stability of mRNA species coding for proteins essential for division in irradiated cells was also measured. The mean functional lifetime of these mRNA species was 1 hr. The data demonstrate the existence of a specific segment of the population consisting of cells which have completed transcription related to division but not concomitant translation and which can recover from the radiation injury without synthesis of additional RNA. Thus, initial recovery of the ability to divide has an obligate requirement for protein synthesis but no corresponding requirement for nucleic acid synthesis during the period when original messenger remains intact.

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Section: Discussionsupporting

confidence: 92%

Radiosensitivity of Mammalian Cells

Walters¹,

Petersen²

1968

Biophysical Journal

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“…However, the specific radioactivity of the amino acid pool was not determined in this study. Variations in the efficiency of polysomes have been found during the maturation of reticulocytes in citro (Knopf and Lamfrom, 1965;Trakatellis et al, 1965a), but not in ciro (Glowacki and Millette, 1965). Polysome efficiency was furthermore observed to vary during the in citro recovery of reticulocytes after the dissociation of their polysomes by both NaF (Coconi et al, 1966) and ethionine (Villa-Trevino et al, 1964).…”

mentioning

confidence: 88%

mentioning

confidence: 99%

Metabolically induced shifts in the translational efficiency of yeast spheroplast polysomes

Vessey¹,

Keck²

1970

Biochemistry

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This paper presents a study into the in cico translational efficiency of yeast polysomes as their level passes through a cycle of buildup, constancy, and subsequent decline during the incubation of freshly protoplasted cells in growth medium. The in cico rate of protein synthesis was determined from amino acid incorporation data as corrected by two independent methods for the specific radioactivity of a precursor, ciz., the cellular pool of free amino acids and nascent protein. During the initial phase of polysome buildup the translational efficiency is at first very high but declines to a lower value before the maximum level of cellular poly-C ytoplasmic levels of mRNA in eucaryotic cells are generally estimated by methods which are restricted to the assay of bulk mRNA or, at best, to relatively large heterogeneous populations of messengers. With certain restrictions, however, it is possible to experimentally determine the relative changes in the cellular amounts of a given mRNA species from the kinetics of synthesis of the respective protein. This indirect method is based on the assumption that at any given time the rate of synthesis of a protein (dP/dr) is proportional to the amount of its functional mRNA ( M ) , as expressed by the equationwhere k,, is the rate constant for protein synthesis. Thus, if further mRNA synthesis is inhibited, the remaining population of mRNA molecules (Mo) will decay with presumably first-order kinetics and in the process sustain the synthesis of a limited amount of protein (P) which can be computed from the integrated form of eq 1, i.e.where kdm is the rate constant for mRNA decay and t the time elapsed after the inhibition of mRNA synthesis. As t approaches effective infinity the amount of mRNA at time zero can be computed from the reduced form of eq 2, i.e.

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Synthesis of RNA and protein in relation to oral regeneration in the ciliate Stentor coeruleus

Burchill

1968

J. Exp. Zool.

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The effects of actinomycin D, puromycin, and cycloheximide on oral regeneration and macromolecular syntheses in the ciliate Stentor coeruleus were investigated. At concentrations which significantly reduced the rate of RNA synthesis (actinomycin D) and protein synthesis (puromycin and cycloheximide), these inhibitors prevented the completion of development of most cells treated prior to stage "late 4" of regeneration. Cells exposed to the inhibitors in stages "late 4" or 5 were, for the most part, delayed or not affected. Cells treated after stage 5 were unaffected. The oral primordia of many cells arrested in stages "2-3" through 4 were subsequently resorbed, whereas cells blocked in stage 5 retained their oral organelles for the period of the block. The results suggest that both RNA and protein syntheses are essential to regeneration and that the final synthesis of essential macromolecules occurs during stage 5.

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Studies on rat reticulocyte polysomes during in vitro maturation

Cited by 12 publications

References 36 publications

Radiosensitivity of Mammalian Cells

Radiosensitivity of Mammalian Cells

Metabolically induced shifts in the translational efficiency of yeast spheroplast polysomes

Synthesis of RNA and protein in relation to oral regeneration in the ciliate Stentor coeruleus

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