Sulfated macromolecules in early embryos of Limnaea

An attempt has been made to partially characterize the substance responsible for the rhythmic incorporation of 35S (inorganic sulfate) in the course of the cell cycle in early Limnaea embryos. This trichloroacetic acid (TCA) insoluble substance is partly pronase sensitive, and dissociable into two fractions after treatment with NaCl. One of these remains TCA-insoluble while the other is TCA soluble but precipitable by cetyl pyridinium chloride. Thus, unlike in some other higher organisms, the major part of the inorganic sulfate is incorporated here into a fraction which is not a single mycopolysaccharide, but is more likely to be a protein-mucopolysaccharide complex, rather like the chondromucoprotein of chick-embryo cartilage.