Further Investigations on Transcription and Translation in Limnaea Embryos

1971 ◽  
Vol 49 (8) ◽  
pp. 926-932 ◽  
Author(s):  
R. L. Brahmachary ◽  
S. R. Palchoudhury
Keyword(s):  
Amino Acid ◽  
Density Gradient ◽  
Messenger Rna ◽  
Sucrose Density Gradient ◽  
Rapid Rise ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Final Development ◽  
S Peak ◽  
Trochophore Stage

14C-amino acid incorporation in uncleaved Limnaea eggs is slight but it slowly increases up to the trochophore stage followed by a rapid rise during the veliger stage when 32P incorporation is falling. There is a peak in the 10 S region of the sucrose density gradient profile of morula RNA. Presumably this morula RNA (messenger RNA) is necessary for final development and hatching of the veliger. The trochophore 10 S peak is the largest, stable and strongly depressed by actinomycin; on the contrary, the veliger 10 S RNA peak is insensitive to actinomycin and seems to be meant for immediate translation.Actinomycin treatment of the uncleaved eggs prevents cleavage in a certain percentage of eggs but in the rest the treatment is not effective until the trochophore stage.

scholarly journals The effect of whole-body X-irradiation of guinea pigs on liver ribosomes

1968 ◽  
Vol 109 (4) ◽  
pp. 495-505 ◽  
Author(s):  
E. J. Hidvégi ◽  
J. Holland ◽  
Elisabeth Bölöni ◽  
P. Lónai ◽  
F. Antoni ◽  
...  
Keyword(s):  
Amino Acid ◽  
Guinea Pigs ◽  
Sucrose Density Gradient ◽  
Whole Body ◽  
Radiation Doses ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
X Irradiation ◽  
Liver Ribosomes

1. The size distribution of aggregates of liver ribosomes and their protein-synthesizing ability in vitro were studied shortly after X-irradiation of guinea pigs. 2. Sucrose-density-gradient analysis of the mitochondrial supernatant after treatment with deoxycholate revealed a gradual increase in the number of polysomes, reaching a maximum between 9 and 15 hr. after irradiation. At that period the amount of ribonucleoprotein particles reached a level 25–30% above the control. This finding was confirmed by analytical-ultracentrifugal analysis and electron microscopy. Experiments were conducted to exclude the possibility that the enrichment of polysomes in the irradiated animals had occurred during the isolation procedure. 3. The protein-synthesizing ability of total ribosomal particles was measured in vitro. This showed an increase in amino acid incorporation parallel to the progressive enrichment of polysomes. At radiation doses of up to 1000r. the protein-synthesizing capacity was dependent on the radiation dose: the higher the dose the higher the amino acid incorporation, reaching 40–60% above the control at the period of maximal polysome enrichment. Amino acid incorporation remained at this level after radiation doses of between 1000 and 3000r. The enhanced protein-synthesizing activity was due solely to the increase in the proportion of polysomes, since irradiation was without effect on the activity of single ribosomes. 4. The results of the experiments are discussed in the light of our knowledge of the effect of radiation on protein synthesis.

Post-microsomal fractions from rat brain which stimulate ribosomal amino acid incorporation

1969 ◽  
Vol 47 (2) ◽  
pp. 75-78 ◽  
Author(s):  
M. R. V. Murthy
Keyword(s):  
Amino Acid ◽  
Rat Brain ◽  
Bond Formation ◽  
Peptide Bond ◽  
Sucrose Density Gradient ◽  
Peptide Bond Formation ◽  
Amino Acid Incorporation ◽  
Transfer Rnas ◽  
Complete Inactivation ◽  
Acid Incorporation

Post-microsomal fractions from rat brain were prepared which stimulated the synthesis of protein when endogenous mRNA was available and enhanced the synthesis of polyphenylalanine in the presence of poly-U and monomeric ribosomes. The amino-acid-activating (or transfer) enzymes did not appear to be responsible for the observed effect since the reaction mixture contained sufficient amounts of these enzymes to permit an optimum rate of amino acid incorporation. The effect was not solely due to the presence of messenger or amino acid transfer RNAs since the activity of the fractions was only partly reduced by prior treatment with ribonuclease. Heating led to complete inactivation of the fractions. Results from amino-acid-incorporation experiments and from sucrose density-gradient centrifugations indicate that the effect might be produced at two levels, one at the level of formation or preservation of polyribosomal structure and the other possibly at the level of peptide bond formation.

scholarly journals EVIDENCE FOR REGULATION OF PROTEIN SYNTHESIS AT THE TRANSLATION LEVEL IN RESPONSE TO DIETARY ALTERATIONS

1967 ◽  
Vol 33 (3) ◽  
pp. 657-663 ◽  
Author(s):  
Alexandra von der Decken
Keyword(s):  
Amino Acid ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Amino Acid Incorporation ◽  
Sucrose Density Gradient Centrifugation ◽  
Protein Ratio ◽  
Acid Incorporation ◽  
Protein Free Diet ◽  
Protein Rich

Rats were maintained for several days on a protein-free diet which, approximately 14 hr before decapitation, was changed to a protein-rich diet. Microsomal subfractions of liver were obtained by sucrose density gradient centrifugation. The sedimentation patterns of the microsomal subfractions and of the polysomes were found to be unchanged after the alteration of the diet whereas the ability to incorporate amino acid was markedly enhanced. No significant differences in the RNA/protein ratio of the microsomal subfractions were observed. The changes in amino acid incorporation which were unrelated to concurrent changes in the amount of polysomes are discussed.

scholarly journals Transferability of N-terminal mutations of pyrrolysyl-tRNA synthetase in one species to that in another species on unnatural amino acid incorporation efficiency

Amino Acids ◽  
2020 ◽  
Author(s):  
Thomas L. Williams ◽  
Debra J. Iskandar ◽  
Alexander R. Nödling ◽  
Yurong Tan ◽  
Louis Y. P. Luk ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Genetic Code ◽  
Unnatural Amino Acids ◽  
Trna Synthetase ◽  
Unnatural Amino Acid ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Genetic Code Expansion ◽  
Incorporation Efficiency

AbstractGenetic code expansion is a powerful technique for site-specific incorporation of an unnatural amino acid into a protein of interest. This technique relies on an orthogonal aminoacyl-tRNA synthetase/tRNA pair and has enabled incorporation of over 100 different unnatural amino acids into ribosomally synthesized proteins in cells. Pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNA from Methanosarcina species are arguably the most widely used orthogonal pair. Here, we investigated whether beneficial effect in unnatural amino acid incorporation caused by N-terminal mutations in PylRS of one species is transferable to PylRS of another species. It was shown that conserved mutations on the N-terminal domain of MmPylRS improved the unnatural amino acid incorporation efficiency up to five folds. As MbPylRS shares high sequence identity to MmPylRS, and the two homologs are often used interchangeably, we examined incorporation of five unnatural amino acids by four MbPylRS variants at two temperatures. Our results indicate that the beneficial N-terminal mutations in MmPylRS did not improve unnatural amino acid incorporation efficiency by MbPylRS. Knowledge from this work contributes to our understanding of PylRS homologs which are needed to improve the technique of genetic code expansion in the future.

scholarly journals FRUCTOSE-AMINO ACIDS IN LIVER: STIMULI OF AMINO ACID INCORPORATION IN VITRO

1955 ◽  
Vol 215 (1) ◽  
pp. 111-124 ◽  
Author(s):  
Henry Borsook ◽  
Adolph Abrams ◽  
Peter H. Lowy
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Incorporation ◽  
Acid Incorporation
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