Figure 3.

Measurement of β-galactosidase expression in the yeast cells. (a) Clones generated are: single copy, pAMTS61; multiple tandem copies, pAMTM61a (4 copies); pAMTM61b (5 copies), multiple, 3 tandem and 1 reverse copy, pAMTMR61; single copy 61-mer duplex sequences, pAMDC61. (b) Graph showing β-galactosidase expression in yeast cells carrying different plasmids in the growth phase. After transferring cells from glucose to galactose medium, aliquots of culture were removed and (β-galactosidase expression measured intermittently from starting point of culture to the exponential phase of growth. Numbers in parentheses represent transformants from two separate clones. The experiments were repeated at least 5 times for all transformants and best curves are shown for each. The maximum error observed was ± 5 units, (c) Table shows the number of independent transformants tested for β-galactosidase expression at OD₆₀₀ = 1. Activity unit is corrected in all instances by the plasmid maintenance factor (stability).