Wall loss and origin of soluble carbohydrates during mating of Chlamydomonas reinhardi

In the mating reaction between gametes of the green alga Chlamydomonas reinhardi, a lytic factor which solubilizes the cell wall is released. It has been shown that carbohydrates accumulate in the supernatant of mating gametes. We present here data which support the notion that the released carbohydrates arise from solubilized gametic cell walls. The evidence is based, in part, on the comparison of the carbohydrates and amino acids in the acid hydrolysates of cell-free supernatants to the reported composition of isolated cell walls. In both cases the three predominant sugars are mannose, arabinose and galactose, and also, in both cases, large amounts of the amino acid hydroxyproline are present. In addition, it is shown that if gametic cell walls are removed prior to mating interactions by treatment with a preparation of lytic factor, much less carbohydrate is subsequently released into the supematant, when such ‘nake’ gametes are mated.