Glasgow Warriors have signed prop Siua Halanukonuka from Highlanders on a two-year deal.
Edinburgh hooker George Turner has joined PRO12 rivals Glasgow Warriors on a season-long loan.
Stormers fly-half Brandon Thomson will re-join Glasgow Warriors on a permanent contract ahead of the 2017-18 season.
Glasgow and Scotland pair Jonny Gray and Stuart Hogg both face up to six months on the sidelines after undergoing surgery.
Scotland flanker Ryan Wilson says that he and his team-mates need to continue their momentum by beating Australia.
Champions Cup holders Saracens will face Clermont Auvergne, Ospreys and Northampton Saints in next season's pool stages.
Glasgow Warriors have re-signed lock Kiran McDonald and extended winger Ratu Tagive's stay, with both men signing one-year deals.
Scarlets and Exeter dominate after they triumphed in the PRO12 and Premiership finals.
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