The Seattle Seahawks have signed former St. Louis Rams first-round pick T Alex Barron following a tryout during rookie mini-camp this weekend. In addition, they also signed former Cincinnati T Andrew Mitchell and undrafted rookies CB Donny Lisowski and TE Cooper Helfet. To make room, they released CB London Durham, LB Adrian Moten, T Jon Opperud and G/C Brent Osborne.