ROWE. Hypoxia and malnutrition in newborn rats: effects on RNA, DNA, and protein in tissues. Am. J. Physiol. 217(3): 642-645. 1969.-Newborn male rats were exposed to 12% oxygen from 1 to 7 days and their brain weights, DNA, protein, or RNA content studied at 7, 21, or 35 days. At 35 days, studies were made of cerebrum and cerebellum and of the liver, muscle mass, carcass fat, and skeletal collagen. These rats were compared with normal rats and with rats malnourished from 1 to 7 days. Hypoxia caused a failure of brain DNA and protein content to increase. At 35 days, the hypoxic rats had reduction in body weight, cerebellar weight, liver weight, muscle mass, muscle cell number, and skeletal collagen. There was an increase in carcass fat. The cerebellar DNA and protein content were reduced whereas in the cerebrum, liver, and muscle, the RNA content was very low (not measured in cerebellum). It is concluded that during hypoxia cell multiplication is prevented, but subsequently there is interference with RNA production and protein synthesis with growth retardation. In the brain the cerebellum is damaged more than the cerebrum. The effects of hypoxia can not be ascribed entirely to restricted food intake.

ExtractThe relations of total zinc, manganese, nucleic acids, and protein in the livers of control, hypophysectomized, and calorie-restricted rats were evaluated by regression analysis and analysis of covariance (tables I through V).The most striking findings were the demonstration of a continuous relation between RNA and zinc in the livers of the control rats and of experimental groups ( fig. 2), and an absolute increase in the content of manganese in the livers of the calorie-restricted animals ( fig. 3).It is suggested that zinc is important for the maintenance of ribonucleic acid synthesis and subsequent protein synthesis in mammalian tissues. SpeculationIn biological tissues, ribonucleic acid is a necessary precursor for protein synthesis; possibly zinc, acting as a cofactor, is of equal importance. Introductionacid (DNA), ribonucleic acid (RNA), and protein.These interrelations are considered for control rats, In an earlier paper [3] it was reported that during a rats receiving adequate protein but inadequate calories, variety of circumstances affecting growth of rats and for rats that had been hypophysectomized. (endocrine imbalance, calorie restriction) the ratios Regression equations presented in this communicain liver of both zinc and ribonucleic acid to deoxyribo-tion contain a common factor, liver weight, through nucleic acid appeared to parallel each other closely. which both the dependent and independent variables This suggested that the two components were related are calculated. This, of course, leads to somewhat within the cell. The present study was designed to spurious correlations. The emphasis of the statistical examine the relation of zinc and manganese to nucleic analysis, however, is not on the fitted equations but acids and protein within the rat liver by more definitive on the comparisons of the sets of data by analysis of statistical methods in order to strengthen or discard covariance. This permits comparisons of animals of the previous finding. varying ages and sizes in a way that is biologically Statistical analysis, namely regression analysis and meaningful. analysis of covariance, was utilized to inspect the relaAnalysis of covariance affords a sensitive statistical tion of total zinc (Zn) and also total manganese (Mn) method by which two regression lines may be compared in rat liver with the liver content of deoxyribonucleic to determine whether they are from two different pop-