Factors influencing the uptake of DNA by Neurospora crassa

Under optimal conditions intact Neurospora crassa cells incorporated nearly the same amount of 3H-labelled DNA as that of the endogenous DNA content of cells. After 18 h of incorporation more than 80 per cent of the radioactivity was retained in the cells. A maximum uptake of exogenous DNA occurred at 28 degrees C, pH 6.35, in the presence of 100 mM calcium when the concentration of donor DNA was 150 micrograms/ml. Denatured DNA was incorporated at a higher rate than native DNA. The present findings suggest that the uptake of DNA by Neurospora crassa is a biologically active process.