How can I prevent aggregation of protoplasts during a transformation with Physcomitrella patens?

While isolating/transforming Physcomitrella patens protoplasts (Cove et al., Jove), especially after centrifugation (250 g for 5 min), my protoplasts start to aggregate. How can I prevent this? Is...

16 April 2015 9,665 7 View