Studies on the translation of genetic message: role of ribosomal protein S12 in cistron selection.

Each cistron on an mRNA molecule has a certain probability of being selected for translation by a given species of ribosome. This cistron specificity, or uniqueness, results from several determinants in the protein synthesizing system, each independently contributing to the potential of that cistron as an efficient initiator. This thesis includes a review of the research done in recent years to demonstrate the factors which influence the efficiency of initiation on a given cistron. Following this, the role of one of these factors, ribosomal protein S12, is studied in detail. Most known RNA bacteriophages code for three proteins. These are the coat, which is the major structural protein of the virus particle, the A protein which is required for proper assembly of the virus, and synthetase, which combines with several of the host coded peptides to form an enzyme required for transcription of the phage. These viral messages are often used to study protein synthesis because they are small, and their protein products can be easily separated and compared. This research project is designed to study the in vitro protein synthesizing system of an E. coli streptomycin resistant mutant. Plaque formation by an RNA phage indicates that it can infect the parent but not the mutant

Hormone receptors in bone: an evaluation of the uptake of estrogen and cortisol into bone cells

The uptakes of the radioactive hormones, 3H-estradiol-17β and 3H-cortisol, in bone cells were evaluated. Nuclear and cytoplasmic fractions were prepared from pulverized bone. Incubations were done in 3H-estradiol-17β, 3H-estradiol-17β plus tenfold amount of unlabelled estradiol, 3H-cortisol, and 3H-cortisol plus tenfold unlabelled cortisol. There was no difference in the uptake of 3H-estradiol-17β alone or the 3H-estradiol-17β plus unlabeled estradiol, leading to the conclusion that there is no specific binding of estrogens in bone cells. Cortisol uptake studies initially showed competitive uptake, but this uptake was later proven to be due to Transcortin, a plasma corticosteroid binding globulin. After dexamethasone uptake studies, a specific cellular binding glucocorticoid, no uptake was seen - signifying the absence of a cytoplasmic binding site for cortisol in bone. The lack of specific binding suggests absence of estrogen and cortisol receptor molecules in bone cells