Pipettes. Pipettes were made by pulling quartz capillaries (ID 0.5 mm, OD 1 mm) in a Sutter P-2000 pipette puller. We used a pulling program with parameters HEAT = 700, FILAMENT = 4, VELOCITY = 10, DELAY = 120, PULL = 60 which typically resulted in 6 pulls before separation. The pipette was immediately inspected under an optical microscope to be sure it was of acceptable quality.