RNA and protein synthetic patterns during germination of Polysphondylium pallidum microcysts

1978 ◽  
Vol 24 (4) ◽  
pp. 480-486 ◽  
Author(s):  
David I. Gwynne ◽  
Danton H. O'Day

During microcyst germination in the cellular slime mould Polysphondylium pallidum, an immediate rapid increase in the rate of protein synthesis ([3H]leucine incorporation) is observed within 15 min after the initiation of germination. The data, corrected for amino acid pool changes, reveal that the rate of protein synthesis reaches its peak at [Formula: see text], after which it decreases. A low level of RNA synthesis ([3H]uridine incorporation) is observed after 1 h and this rate increases markedly after 2 h. Analysis of the RNA species shows a low level of synthesis of all ribosomal RNA's which begins between 1 and 2 h and increases after 2 h. The synthesis of a heterogeneously distributed, poly(A)-containingfraction of RNA (presumptive mRNA) is initiated some time after 2 h and the synthesis of a small molecular weight species in the 4–5S region is observed after 3 h. Thus, it seems that Polysphondylium microcysts show sequentially initiated synthesis of RNA during germination.

Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 323-333
Author(s):  
J.G. McNally ◽  
E.C. Cox

Whorls of the cellular slime mould Polysphondylium pallidum originate as spherical cell masses that during normal morphogenesis produce tips only at equidistant positions around their equator. We have observed a series of new patterns in whorls that differ from normal whorls only in that they are larger or more elongated. Among the novel patterns found were arrays of tips distributed fairly regularly over the whole whorl surface, as well as striped patterns detected at earlier stages with a tip-specific antigen. These altered patterns demonstrate that a whorl's size and shape are by themselves important factors in pattern determination. We have compared the range of observed patterns to those predicted by a variety of different theories. We find that while no one theory can account in detail for all of our observations, predictions based on Turing's scheme of pattern formation come the closest.


1969 ◽  
Vol 28 (02) ◽  
pp. 248-254 ◽  
Author(s):  
R. T. Hunt ◽  
A. R. Hunter ◽  
A. J. Munro

Analysis of the effects of amino acid starvation in reticulocytes is comparatively simple compared with similar analysis in other tissues of whole organisms. This is mainly because of the absence of RNA synthesis in reticulocytes, but also because the bulk of the protein being synthesized is haemoglobin, a protein whose structure is completely known. The absence of RNA synthesis eliminates complications that would otherwise arise through RNA-mediated control mechanisms which in turn might mask the effects of amino acid starvation on the protein synthetic machinery in the cells (Munro, 1969). Consequently reticulocytes have been used to study the effect of amino acid starvation on the actual process of protein synthesis and assembly.


1976 ◽  
Vol 158 (2) ◽  
pp. 409-417 ◽  
Author(s):  
D C Kilpatrick ◽  
J L Stirling

An alpha-D-galactosidase was detected in cells of the cellular slime mould, Dictyostelium discoideum, at all stages of development. Its specific activity was highest during early development (interphase), and this accumulation of enzyme appears to require protein synthesis de novo. Its subcellular distribution differs from that of other D. discoideum glycosidases, since most activity was recovered in the soluble fraction. No evidence was obtained for more than one isoenzymic form after subjection of extracts to electrophoresis and various chromatographic procedures. It is excreted from the cell during development, but no evidence was found for an extracellular function for the enzyme.


1973 ◽  
Vol 136 (3) ◽  
pp. 795-802 ◽  
Author(s):  
A. K. M. Bartelink ◽  
C. A. D. De Kort

By using cycloheximide, an inhibitor of cytoplasmic protein synthesis, conditions were investigated to estimate in vivo the extra- and intra-mitochondrial contributions to the synthesis of organelle protein in the flight muscles of Colorado beetles. With 4-day-old beetles about 15% of the [14C]leucine incorporation into mitochondrial protein is resistant to the action of cycloheximide. The incorporation into cytosol protein is inhibited by more than 99.5% with cycloheximide. During the first hour after precursor administration the incorporation into mitochondrial protein proceeds, in both the presence and the absence of cycloheximide, at a more-or-less linear rate with time. The cycloheximide-resistant amino acid incorporation is sensitive to the inhibitor of mitochondrial protein synthesis, chloramphenicol. The uncertainties inherent in the use of cycloheximide were discussed in arriving at the conclusion that about 15% of the mitochondrial protein is formed inside the organelle.


1969 ◽  
Vol 28 (2) ◽  
pp. 248-254 ◽  
Author(s):  
R. T. Hunt ◽  
A. R. Hunter ◽  
A. J. Munro

Analysis of the effects of amino acid starvation in reticulocytes is comparatively simple compared with similar analysis in other tissues of whole organisms. This is mainly because of the absence of RNA synthesis in reticulocytes, but also because the bulk of the protein being synthesized is haemoglobin, a protein whose structure is completely known. The absence of RNA synthesis eliminates complications that would otherwise arise through RNA-mediated control mechanisms which in turn might mask the effects of amino acid starvation on the protein synthetic machinery in the cells (Munro, 1969). Consequently reticulocytes have been used to study the effect of amino acid starvation on the actual process of protein synthesis and assembly.


1995 ◽  
Vol 5 (2) ◽  
pp. 87-97 ◽  
Author(s):  
U. Gerth ◽  
D. Bernhardt

AbstractImbibed embryos of after-ripened and secondarily thermo- and FR-dormant Agrostemma githago seeds were investigated as to their ability to synthesize DNA, RNA and proteins with the aim of finding characteristic differences connected with the induction and maintenance of developmental arrest. A gradual decrease in DNA synthesis was observed during the induction of thermodormancy. However, DNA synthesis was stimulated up to that of embryos of 30–h-imbibed after-ripened seeds within 24 h approximately after transferring the thermodormant seeds into temperatures which normally allow germination. DNA synthesis of embryos of FR-dormant seeds remained constant at a relatively low level during 7 d FR and another 7 d dark incubation. RNA synthesis decreased to different extents during induction of thermo- and FR-dormancy when it was arrested at a relatively low level in seeds transferred to temperatures which normally allow germination. Processes leading to an increase in RNA synthesis such as in embryos of after-ripened seeds appeared to be quantitatively and/or qualitatively repressed. Interestingly, protein synthesis was extremely depressed during induction of thermodormancy whereas it was slightly stimulated during induction of FR-dormancy. Nevertheless two-dimensional protein PAGE revealed several polypeptides which were new, increased, decreased or not synthesized predominantly in axes of thermo- and FR-dormant seeds in comparison to germinating after-ripened seeds. It is suggested that a connection exists between these polypeptides and the repression of germination. After transferring seconarily dormant seeds to temperatures which normally allow germination, a temporary stimulation of protein synthesis could be observed in both cases.


1977 ◽  
Vol 28 (1) ◽  
pp. 49-60
Author(s):  
S.P. Gregory ◽  
V.A. Hilder ◽  
N. Maclean

Nuclei isolated from Xenopus erythrocytes can be transcriptionally reactivated by exposure to certain cytoplasmic proteins. The types of RNA synthesized during this reactivation have been studied and compared with those present in, or synthesized by, isolated nuclei not so reactivated or in entire Xenopus erythrocytes. In all cases, the pattern of transcription indicates the synthesis of a broad range of low molecular weight RNAs. Competitive hybridization demonstrates that the reactivated nuclei synthesize some transcripts not normally produced by the isolated nuclei and we have shown that a proportion of these possess amino acid-accepting activity. The significance of these results is discussed in relation to the control of gene activity in these cells.


1973 ◽  
Vol 72 (4) ◽  
pp. 684-696 ◽  
Author(s):  
Amirav Gordon ◽  
Martin I. Surks ◽  
Jack H. Oppenheimer

ABSTRACT The in vivo and in vitro stimulation of rat hepatic mitochondrial protein synthesis by thyroxine (T4) was compared. In confirmation of Buchanan & Tapley (1966). T4 added to isolated mitochondria rapidly stimulated [14C] leucine incorporation into mitochondrial protein. The in vitro stimulation was reversed after T4 was removed by incubating the mitochondria with bovine serum albumin (BSA). The decrease in T4 stimulation of protein synthesis appeared proportional to the T4 removed by BSA. Thus, it appears probable that exchangeable T4 controls the in vitro system. In contrast, the increase in mitochondrial protein synthesis which was observed 3 to 4 days after pretreatment of hypothyroid rats with labelled and non-radioactive T4 was not reversed by BSA treatment. Moreover, mitochondrial radioactivity could not be extracted with albumin. The in vivo phenomenon does not, therefore, appear to be related to exchangeable hormone in the mitochondria. Furthermore, the estimated quantity of T4 associated with mitochondria after in vivo stimulation was at least two orders of magnitude less than that required to produce comparable stimulation of mitochondrial protein synthesis in vitro. These findings strongly suggest that in vitro and in vivo stimulation of amino acid incorporation by T4 may be mediated by different biochemical mechanisms.


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