Montreal-based Class I railroad carrier CN said yesterday that its Board of Directors formally announced that CEO Luc Jobin has left the company, effective immediately, and replaced him with Jean-Jacques Ruest. Ruest, a 22-year CN veteran, will serve as interim president and CEO until a new, permanent replacement has been named, and he has served as executive vice president and chief marketing officer for the past eight years. CN said an international search for a new CEO is now underway.