I thank Randy Schekman for generously supplying a number of strains and plasmids, Richard Gardner for helpful advice in scoring the HOL1-1 mutation, and Mark Rose for strains and encouragement. Fred Volkert suggested the “upside-down” Southern blotting procedure, and Karen Malatesta developed it for laboratory exercises at Princeton University and was kind enough to share it. Jingdong Liu of the University of Utah developed MacPlasmap and generously distributes it as shareware. It was used to draw the plasmid maps found in Figure 1. Jocelyne Noveral and Darlene Bramucci have been instrumental in helping the development of this laboratory and increasing student understanding, Gwen Rivnak has made much media and many reagents, and Amy Vollmer's encouragement and constructive criticism greatly helped me improve the manuscript. I especially thank Swarthmore students enrolled in Bio21 and Bio14 for their enthusiasm, constructive criticism, and love of learning.
