Effect of 5′-methylthioadenosine on nucleolar morphology and RNA metabolism in cultured Xenopus laevis cells

In the presence of 5′-methylthioadenosine (MTA), nucleoli of cultured Xenopus laevis cells display a highly irregular morphology, which suggests that this naturally occurring nucleoside interferes with rRNA metabolism. In agreement with these cytological results a reduction in the amount of newly-synthesized rRNA was observed in cells incubated with 5′-methylthioadenosine.