A simple method for the purification of reticulocyte globin messenger ribonucleic acid

A relatively simple and inexpensive method has been developed for the preparation of highly purified rabbit reticulocyte globin mRNA. After phenol extraction, polysomal RNA was chromatographed on Sigmacell type 38 cellulose and Sepharose 4B. The resulting mRNA preparation has a purity in excess of 90%. No selective loss of either alpha or beta globin mRNA is observed.

Determination of mRNA half-life in HeLa cultures by a poly(A)-independent direct analysis of specific radioactivity of mRNA

mRNA specific radioactivity in HeLa cultures exposed to (3H)uridine (10 muM) was determined directly by a highly selective poly(A)-independent method which we have described previously. Neither uridine in mRNA nor UTP approached the specific radioactivity of the exogenous (3H)uridine, but attained steady-state specific radioactivities which remained a third below the value of the added precursor. Using the labeling data for the evaluation of mRNA turnover, previously described by Greenberg, mRNA half-life in exponentially growing HeLa cultures was found to be 0.87 times the cell doubling time. Decay curves of mRNA in prelabeled cultures were in accordance with these values (half-life equals 0.79 times the cell doubling time) when corrected for growth and also for "reutilization" which was accomplished by relating uridine labeling in mRNA to UTP specific radioactivity. The experiments showed that an exact evaluation of mRNA turnover is possible only when the following points are taken into account. a) A constant supply of exogenous labeled uridine must be provided to guarantee a constant specific radioactivity of UTP. b) Labeling of CTP and of cytidine in RNA are delayed when compared with UTP and uridine in RNA. Corrections for cytidine labeling in RNA are therefore required. c) As rRNA approached a definitely lower steady-state specific radioactivity than mRNA, mRNA specific radioactivities must be determined directly (i.e. by radioactivity and absorbance at 260 nm in isolated mRNA fractions) in order to evaluate true turnover of this RNA species.

Studies on the anti-oestrogenic and oestrogen-like action of clomiphene citrate animal experiments

The anti-oestrogenic and oestrogen-like potencies of clomiphene citrate are presumably mainly responsible for the mode of action of this synthetic compound in different organs of the female endocrine system. The investigations described in this paper should give more informations about these properties of clomiphene. Therefore the in vivo effect of cis- or trans-clomiphene on some metabolic pathways of the uterine tissue was tested. Studying the influence of cis- or trans-clomiphene on the ³H-oestradiol uptake into uterine tissue in vivo, the cis-isomer indicated the higher anti-oestrogenic effectiveness. In contrast to this observation both isomers were able to imitate biochemical effects of natural oestrogens in the uterus, i.e. the stimulation of the protein- and RNA-synthesizing activity of this organ. These biochemical alterations however, appeared some hours later as compared with 17β-oestradiol. On the base of these results and of experimental data obtained from the literature a model for the mode of action of clomiphene in the female reproductive system is proposed.