Variations in the levels of aminoacylation and modified nucleotide content between total tRNAs from chloroplasts and etioplasts in cucumber cotyledons

1995 ◽  
Vol 16 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Chelliah Jayabaskaran ◽  
Shailaja Hande
Keyword(s):  
Nucleotide Content ◽  
Cucumber Cotyledons

Codon Usage Bias Covaries With Expression Breadth and the Rate of Synonymous Evolution in Humans, but This Is Not Evidence for Selection

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1191-1199
Author(s):  
Araxi O Urrutia ◽  
Laurence D Hurst
Keyword(s):  
Codon Usage ◽  
Codon Bias ◽  
Synonymous Codon ◽  
Nucleotide Composition ◽  
Synonymous Codon Usage ◽  
Synonymous Substitutions ◽  
Numerous Species ◽  
Nucleotide Content ◽  
Expression Breadth ◽  
Human Genes

Abstract In numerous species, from bacteria to Drosophila, evidence suggests that selection acts even on synonymous codon usage: codon bias is greater in more abundantly expressed genes, the rate of synonymous evolution is lower in genes with greater codon bias, and there is consistency between genes in the same species in which codons are preferred. In contrast, in mammals, while nonequal use of alternative codons is observed, the bias is attributed to the background variance in nucleotide concentrations, reflected in the similar nucleotide composition of flanking noncoding and exonic third sites. However, a systematic examination of the covariants of codon usage controlling for background nucleotide content has yet to be performed. Here we present a new method to measure codon bias that corrects for background nucleotide content and apply this to 2396 human genes. Nearly all (99%) exhibit a higher amount of codon bias than expected by chance. The patterns associated with selectively driven codon bias are weakly recovered: Broadly expressed genes have a higher level of bias than do tissue-specific genes, the bias is higher for genes with lower rates of synonymous substitutions, and certain codons are repeatedly preferred. However, while these patterns are suggestive, the first two patterns appear to be methodological artifacts. The last pattern reflects in part biases in usage of nucleotide pairs. We conclude that we find no evidence for selection on codon usage in humans.

Changes in the cyclic nucleotide content in wound tissues during healing

1979 ◽  
Vol 87 (6) ◽  
pp. 625-627 ◽  
Author(s):  
I. M. Nosova ◽  
M. A. Zaidenberg ◽  
V. N. Petrosova ◽  
R. D. Seifulla ◽  
A. A. Karelin
Keyword(s):  
Cyclic Nucleotide ◽  
Nucleotide Content

scholarly journals Evidence for the presence of oligophosphoglyceroyl-ATP in rat offney

1986 ◽  
Vol 240 (2) ◽  
pp. 597-599 ◽  
Author(s):  
W L Hutchinson ◽  
P J Ratcliffe ◽  
J Mowbray
Keyword(s):  
Trichloroacetic Acid ◽  
Adenine Nucleotides ◽  
Purine Nucleotide ◽  
Purine Nucleotides ◽  
Nucleotide Content ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Rapid Equilibrium

The inability to account for large systematic variations in total purine nucleotide content of perfused rat hearts led to the demonstration that the soluble adenine nucleotides are in rapid equilibrium with a highly phosphorylated hetero-oligomeric derivative whose structure appears to be 3-phospho[glyceroyl-gamma-triphospho-5′-adenosine-3′-3-phosp ho]4glyceroyl- gamma-triphospho-5′-adenosine [Hutchinson, Morris & Mowbray (1986) Biochem. J. 234, 623-627]. Analogous techniques to those used with hearts for specifically labelling tissue purine nucleotides followed by extration and purification of nucleotides from the trichloroacetic acid-precipitable fraction show the existence of a corresponding rapid equilibrium between ATP and an oligomeric tetraphosphoadenosine derivative in perfused kidneys.

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