Cubs' Locke St. John: Designated for assignment

St. John was designated for assignment by the Cubs on Tuesday, Meghan Montemurro of the Chicago Tribune reports.

St. John was called up Saturday but spent just one day on the active roster, giving up three runs in two innings. He was optioned Sunday and will now exit the 40-man roster as well just two days later, clearing space for the Cubs to select Robert Gsellman's contract.