Three DNA polymerases of rat ascites hepatoma cells: properties of the enzymes and effect of RNA synthesis on the reactions

Three different DNA polymerases have been isolated from rat ascites hepatoma cells [1--3]. The molecular weight of a DNA polymerase (polymerase C) purified from the soluble fraction of the cells was estimated to be 142 000 by sedimentation on a sucrose gradient, while the molecular weights of two DNA polymerases (polymerase P-1 and P-2) purified from nuclear membrane-chromatin fraction were estimated to be 117 000 and 44 000, respectively, by the same method. Under certain conditions, the poly (dT) strand of poly[(dA)-(dT)] was copied well by the polymerases, especially by the nuclear polymerases. Poly (dC) was a good template for the high molecular weight DNA polymerases C and P-1, but poly(dT) and poly(dA) were not effective templates. By addition of complementary oligoribonucleotides, the single-stranded deoxypolymers were copied by the high molecular weight polymerases C and P-1. When single-stranded fd phage DNA was used as template, the polymerization reactions by the high molecular weight polymerases were stimulated by the concomitant synthesis of RNA. This indicates that the oligoribonucleotide acts as a primer in these reactions.

Effect of anaerobic conditions in bottom waters on the occurrence of red tides at omura bay

The field observation that the occurrence of red tides at Omura Bay may have a close connection with the development of anoxic conditions in bottom waters was tested by bioassays of seawater collected during summer 1971. The stimulating effect of anaerobically-decomposed products of bottom mud on the growth of Gymnodinium type-'65 was examined. The results suggest that the development of oxygen deficiency in the bottom waters of Omura Bay makes the environment favourable for the growth of red tide organisms, both by the supply of inorganic nutrients and of some unidentified stimulants.