Characterization of rapidly labelled rat liver ribonucleic acid showing high affinity for columns of methylated albumin on kieselguhr

Abstract

Most of the rapidly labelled RNA from rat liver submitted to column chromatography on methylated albumin on kieselguhr remains tightly bound to the column and can only be recovered by elution with m-ammonia. The tightly bound RNA is composed mainly of DNA-like RNA. The binding capacity is dependent not only on base composition but also on molecular size: the heavier RNA molecules show a greater affinity to the column than do the lower-molecular-weight components. Rapidly labelled mouse liver and Saccharomyces cerevisiae RNA show similar behaviour to rat liver RNA on columns of methylated albumin on kieselguhr.

Incorporation of [14C]Glucose and [3H]Uridine into the Major Classes of Rna in Mouse Embryos During Preimplantation Development

“…Similar chromatographic profiles were obtained when the column was constructed by the method of Mandell and Hershey (1960) or of Monier et al (1962). Kieselguhr (16 g) was suspended in 80 ml of 0'05M Tris-HCl buffer (pH 6'7) containing 0'05M NaCI and coated with methylated serum albumin by adding 4 ml of a 1 % (w/v) solution of the protein in water.…”

“…The preparation of the methylated albumin has been described by Mandell and Hershey (1960); the construction of the column followed the simplified method of Monier et al (1962). Similar chromatographic profiles were obtained when the column was constructed by the method of Mandell and Hershey (1960) or of Monier et al (1962).…”

“…At the completion of the gradient elution, TD-RNA, having a high affinity for MAK, was eluted from the column with 1M ammonia and each fraction was neutralized immediately on collection (Ellem 1966;Kunz et at. 1970).…”

“…Optical density peaks of RNA from the unlabelled carrier liver cells, although not shown in the figure, always corresponded to peaks of radioactivity. Major fractions of RNA were eluted from the MAK column in tum as sRNA, rRNA, and TD-RNA (see Ellem and Gwatkin 1968;Kunz et al 1970). Eight-cell embryos which developed into morulae over the 24-hr culture period in vitro accumulated 58·7 ± 0·9 pg-atoms of glucose carbon per embryo intracellularly and incorporated radioactive carbon into all major RNA classes.…”

“…Although autoradiographic and biochemical analyses have shown that the synthesis of both transfer and ribosomal RNA (tRNA and rRNA) begin at the four-cell stage of cleavage in the mouse embryo (Mintz 1964;Woodland and Graham 1969), some earlier genetic intervention may be required for embryogenesis in this species since embryos at the two-cell stage display a marked sensitivity to actinomycin D (Silagi 1963;Mintz 1964; Thomson and Biggers 1966;Monesi et al 1970). RNA synthesis intensifies from the morula stage to the blastocyst (Monesi and Salfi 1967) and, from the eightcell stage on, rRNA is a major product of RNA synthesis (Ellem and Gwatkin 1968;Pik6 1970). The rabbit embryo also shares the property of very early synthesis of tRNA with the mouse embryo but differs in the time of onset of rRNA synthesis (Manes 1969(Manes , 1971.…”