49ers’ Donavin Newsom leaves practice in ambulance after collision

The 49ers ended Tuesday's practice early after undrafted rookie linebacker Donavin Newsom was taken from the field in an ambulance about 12 minutes after colliding with safety Chanceller James. Newsom was motionless on the field before he was strapped to a back brace in full uniform, except for his face mask, which was removed. Minutes after practice, head coach Kyle Shanahan said the belief was Newsom sustained a neck injury, but his eyes were open and he had "feeling in his lower half and his hands" before leaving. After the ambulance left, several teammates, including wide receiver Marquise Goodwin, remained on a knee in prayer. James, an undrafted rookie, appeared to immediately sense Newsom was seriously injured after their collision, and was clearly distraught as he ran toward a sideline. The 49ers signed cornerback Asa Jackson, a 2012 fifth-round pick who has 37 tackles, zero interceptions and eight starts in his career. Jackson, 27, a Sacramento native who attended Cal Poly, played in four games last year with the Lions after spending his first four seasons with the Ravens. The 49ers waived undrafted rookie cornerback Zach Franklin, who injured an ankle during training...