The Center for Public Integrity and ProPublica — two MacArthur grantees devoted to investigative journalism — will have their work distributed by the Associated Press to 1,500 American newspapers beginning this month. This new partnership is expected to expand greatly the potential audiences of these nonprofit models while helping to fill gaps in local and regional reporting that have resulted from shrinking news budgets. The AP called the arrangement a six-month experiment that could later be broadened to include other investigative nonprofits, and to serve its nonmember clients, which include broadcast and Internet outlets.