The biological role of ribonucleic acids

Abstract

Next to nothing was known a quarter of a century ago about the biological role and the intracellular localization of the nucleic acids. All that was well established was the existence of two different types of nucleic acids, which correspond to the deoxyribonucleic (DNA) and ribonucleic (RNA) acids of the present day. They were called, respectively, thymonucleic and zymonucleic acids, because purified preparations had only been obtained from thymus and yeast. It was erroneously believed that thymonucleic acid (DNA) is specific to animal cells and that yeast nucleic acid (RNA) is present only in plant cells. However RNA had been isolated from pancreas. A popular hypothesis was that DNA, which was known to contain both ortho-phosphoric acid and nitrogenous bases, might play the role of an intra-nuclear buffer. Such a role is certainly a minor one for the bearer of "genetic information"! One of the first important advances made in the field came from cytochemistry, when in 1924 Feulgen and Rossenbeck designed and utilized their well-known reaction for the detection of DNA. They were immediately able to demonstrate that thymonucleic acid (DNA) is specifically located in the cell nucleus, in plants as well as in animals. Progress on the role and localization of RNA was slower to come, because of the lack of specific cytochemical reactions comparable to the Feulgen tests. Indirect observations by Brachet (1933) strongly suggested, however, that animal cells may contain such References p. 50/54 RIBONUCLEIC ACIDS AND PROTEIN SYNTHESIS in RNA. Values up to 11.5% dry weight have been reported by Vendrely (1946). Work carried out in several different laboratories shows the existence of an excellent correlation between the synthesis of RNA and the synthesis of proteins, provided that the bacterial growth is studied during the logarithmic phase. For instance, Caldwell et al. (1950) found the RNA content of bacteria to be proportional to the growth rate, whatever the experimental conditions (changes in the nitrogen source of the culture medium, presence or absence of inhibitors, normal organisms or slow-growing mutants). Similar findings have been reported by Northrop (1953), Wade (1952) and Price (1952). An important study of Gale and Folkes (1953) shows that staphylococci synthesize proteins in the presence of glucose and amino acids. If purines and pyrimidines are added to this medium, nucleic acids are also synthesized. But the interesting fact is that if the medium contains no amino acids there is no nucleic acid synthesis, whereas the presence of purines and pyrimidines in the medium enhances protein synthesis. There thus exists a strong positive correlation between the nucleic acid content of the cells and the rate of protein synthesis. Gale and Folkes (1953) have also found that protein synthesis and RNA synthesis can be dissociated by the use of antibiotics. For instance, Chloromycetin, aureomycin, and terramycin all inhibit protein synthesis but increase nucleic acid synthesis. However, there is very good evidence (N...

Making aquatic weeds useful II:Nymphoides cristatum(Roxb.) O. Kuntze as feed for an Indian major carpLabeo rohita(Hamilton)

“…Robinson & Ware (1988) also found increasing RNA/DNA ratios even in standard herring larvae until the sac stage. It is known that the rapidly growing organisms apparently synthesize and accumulate RNA needed for protein synthesis (Brachet 1955; Bulow 1970). In the present investigation also, a positive correlation between the concentration of RNA, DNA and RNA/DNA ratios of the muscle and growth of the fish was observed.…”

Factors Influencing Skin Graft Survival From Donors With Ehrlich Ascites Tumor

“…However, the factor responsible for this phenomenon, has not been studied previously. The behaviour of EAT cells was studied by several investigators, both in a natural environment [3,10] and in an artificial environment [5,11,12]. It seems to be clear from these studies that by maintenance of these cells in vitro in isotonic solution, a gradual decrease in their vitality occurs, associated most probably with a modification of various metabolic pathways.…”

Regulation of Bacterial Growth

“…The correlation between the RNA content of cells and their activity in the synthesis of protein, as shown by the pioneering cytological work of Caspersson and of Brachet and their co-workers, was the first indication of the role of ribosomes in protein synthe-sis [see (29)]. In studies beginning in the 1930's it was shown that the RNA or ribosome content of cells correlated well with the rate of growth of animal and plant tissues, with the rate of protein synthesis in particular types of cells, and with the rate of division of microbes.…”

“…Abundant evidence in the form of historical photographs and surveys and an historical site record maintained by the U.S. Forest Service clearly establishes the general stability of the structure and negates Ranse Im's claim-. 29. We are fortunate that at the present time the U.S. Forest Servise, Medicine Wheel District, and the Departmiient of Anthropology, University of WscmCiing, are studying the archeological basis of the strLcitLure.…”