Owen Farrell has been ruled out of England's entire RBS 6 Nations campaign with a knee injury.
Sean O'Brien remains in contention to end an injury-plagued 14 months by making a comeback for the Irish Wolfhounds.
New Scotland call-up Hugh Blake has pleaded for the chance to show he is worthy of a Dark Blue jersey.
Ally Hogg has become the fifth player to commit his future to Newcastle after signing a new two-year deal with the Falcons.
Wasps number eight Ashley Johnson has been cited for an alleged dangerous tackle on Leinster wing Dave Kearney.
Harlequins forward Will Collier has been ruled out for the rest of the season with a ruptured cruciate ligament.
Scotland have confirmed David Denton and Sean Maitland will miss the start of the Six Nations through injury.
Former Australia coach Robbie Deans will take charge of the Barbarians for matches against Ireland and England in May.
Forwards Tom Croft and Christian Day have been called up to England's RBS 6 Nations training squad as injury cover.
Scottish Rugby Union chief executive Mark Dodson has defended Vern Cotter's decision to include Hugh Blake in his squad.