PHILADELPHIA — Pennsylvania Gov. Ed Rendell has resigned as chairman of the Delaware River Port Authority, the two-state agency that operates bridges between Pennsylvania and New Jersey.

Rendell appointed his former chief of staff, John Estey, to succeed him for a five-year term.

Estey, an attorney, is chairman of the Philadelphia Regional Port Authority and board chairman of the Independence Visitor Center Corp. He's been the designated stand-in for Rendell, who has seldom attended DRPA board meetings as chairman.

The authority oversees four Delaware River toll bridges as well as the PATCO high-speed rail line between Philadelphia and Camden, N.J.

MOUNT LEBANON — A suburban Pittsburgh chemistry teacher and tennis coach has pleaded guilty to sending sexually explicit photos and chatroom messages to an undercover agent posing as a 14-year-old girl.The state attorney general says 35-year-old Nicholas Salvo sent the messages in July.Salvo taught chemistry at Mount Lebanon High School and was briefly its tennis coach before he was suspended after he was charged in August.The incidents involve Salvo's home computer. Authorities say there's no indication Salvo did anything similar on computers owned by the school district.