South African scrum-half Ruan Pienaar is to leave Ulster at the end of the season.
Double winners Saracens agree a deal to sign France international hooker Christopher Tolofua from Toulouse next summer.
Premiership side Harlequins sign Samoa international Alofa Alofa, who left La Rochelle earlier this summer.
The head of the Pro12 believes it has a bright future without following the "unsustainable" English and French business models.
Audio & Video
Watch as captains from the teams in rugby union’s Premiership answer some unusual questions before the new season, which kicks off on 2 September.
How to get into rugby union
How to get into rugby union - into the thick of the 15-player game or try rugby sevens, which is making its Olympic debut in 2016.
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World Cup final referee Nigel Owens reveals what he looks for in this 'primal battle'.
What are the basics of rugby union?
Want to brush up on your rugby knowledge? Let BBC Sport be your guide to the unique bits of rugby union.
What's the secret to the perfect place kick?
Wales star James Hook explains how to turn pressure into points in our special iWonder guide.
More powerful than a raging bull?
Just how much force is involved in a rugby scrum and what does it feel like to be in the middle of it?