Protein Polymer Technologies Inc. said Ethicon Inc., a unit of Johnson & Johnson, agreed to invest an additional $300,000 in the development-stage company, for a total $1.7-million investment. San Diego-based Protein Polymer is developing tissue adhesives and wound sealants used in surgery. The companies also extended their research joint venture through 1997. Under their agreement, Protein Polymer will receive a license fee and the option to make the proteins used in the products and at least some of the finished products, while Ethicon will own worldwide marketing rights. Ethicon also agreed to make additional payments to Protein Polymer based on the products' success. Protein Polymer shares rose 12.5 cents to close at $2.50; J&J shares rose 12.5 cents to close at $52.50. Both trade on the NYSE.