IN VITRO BIOSYNTHESIS OF PROTEINS IN HUMAN PLACENTAE FROM NORMAL AND TOXAEMIC PREGNANCIES

The concentration of proteins, RNA and DNA, incorporation of carbon-14 amino acids into proteins and the labelling of RNA in 10 placentae each from normal and toxaemic pregnancies have been investigated. The protein content either on a wet tissue basis or on a dry tissue basis was lower in the toxaemic placenta. In this group of placentae, the concentration of RNA and DNA was also lower as compared with the normal. While there was no change in the RNA/Protein ratio in the two groups of placentae, the DNA/Protein ratio was significantly lower in toxaemic placentae. When the various subcellular fractions were compared, the concentration of protein was lower in the nuclear, mitochondrial, microsomal and pH 5 enzyme precipitate fractions of toxaemic placentae.The incorporation of carbon-14 amino acids into proteins and the labelling of RNA was lower in the various subcellular fractions of toxaemic placentae. The time course of the incorporation of carbon-14 amino acids into proteins and the labelling of RNA in cell-free system increased with time in both groups of placentae, however, these were lower in toxaemic placentae as compared with the normal at the various time intervals studied.From the data presented, it may be concluded that toxaemia exerts some deleterious effect on the biosynthesis of proteins in the placenta. It is suggested that damage to protein synthesis may be the cause of the altered biosynthetic and metabolic activities reported in the placentae during toxaemia.