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Abstract
The patterns of polypeptides synthesized by two co-isogenic monokaryons and the derived dikaryon of the basidiomycete Schizophyllum commune, growing in surface culture, were compared by two-dimensional PAGE after labelling with [35S]sulphate. Synthesis of most of the polypeptides (400 analysed) was common but at day 3 some 30 polypeptides were synthesized in the dikaryon which were not seen in the monokaryons. At this time the dikaryon had formed hyphal aggregates. Ten additional novel polypeptides were being synthesized in the primordia arising from these aggregates at day 4.
In surface culture, monokaryons and dikaryon excreted 4 to 8% of the labelled proteins (over 80 different polypeptides) into the medium compared with only 1 to 2% when cultivation was done in liquid shaken cultures. The polypeptides specifically secreted by the dikaryon at the aggregation stage consisted of seven small polypeptides with molecular weights ranging from 10 to 14 × 103, and two polypeptides with molecular weights 18 × 103 and 26 × 103, respectively. Such differences in excreted proteins between monokaryons and dikaryon were not observed when the mycelia were grown in liquid shaken cultures, indicating a relationship with fruit-body formation.
A comparison of labelled proteins in isolated hyphal walls revealed six polypeptides specifically associated with the walls of monokaryons and dikaryon irrespective of the cultivation method. Among the polypeptides newly appearing in the dikaryon at aggregation two were associated with the walls and co-migrated with the polypeptides of molecular weights 18 × 103 and 26 × 103 excreted into the medium at this stage of development.
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