A SPECIFIC MODIFICATION OF LEUCYL-sRNA OF ESCHERICHIA COLI AFTER PHAGE T2 INFECTION

Changes in Leucine-Specific sRNA after Infection of E. coli by Phages T2 and T4

“…The first is particularly important since differently labeled marker sRNA was not employed as an internal control as was done in the earlier study (1). Table II summarizes the NaCl concentrations at which the different peaks were eluted in the experiment illustrated in Fig.…”

“…MAK Chromatography After a 15 min incubation charged sRNA was isolated from the reaction mixture by extraction on ice three times with water-saturated phenol (Mallinckrodt) and twice with ether. sRNA was precipitated with two volumes of ethanol at -15°G for 1 hr, suspended in 50 ml of 0.05 M sodium phosphate, pH 6.3, plus 0.2 M NaCl, and fractionated on a four layer MAK column (5) eluted according to the methods of Sueoka et al (1,3). Optical density at 260 m/x was monitored quantitatively in a Gilford-Beckman continuous flow spectrophotometer.…”

“…Sueoka et al (1) examined changes in the sRNA of E. coli B before and after infection by phage T2. Among sRNAs for seventeen amino acids examined, only leucine-specific sRNA showed appreciable differences.…”

Changes in Ribonucleic Acid Fractions During Maturation of Mimosa Epicotyl Tissues

“…This suggests that either the degree of reversible addition of terminal nucleosides (2,5,7,26) does not vary with age in vivo, or that the extent of loss of terminal nucleosides is an artifact of extraction procedures (12). Suggestions of changes in distribution of tRNAs have been found in bacteria and animal tissues during development and in response to changes in environmental conditions (9,10,14,18,19,23,27,31,33 (fig 1). However, the fully-developed or relatively mature tissues differed both quantitatively and qualitatively at each age (fig 1).…”

“…In studying quantitative distribution of tRNAs, care must be taken to avoid misinterpretation of structural changes (19,27), such as loss of 3'-OH terminal adenosine which could give misleading evidence for true quantitative changes (20). Vold and Sypherd (30) total epicotyl at each age was calculated using onehalf the average change in fresh weight during the previous 5 days divided by the total new fresh weight.…”