Fig. 10

Green fluorescent protein expression by two-transcription-unit systems. DEG1t placed between two transcription units does not alter, in a considerable way, the production of GPF by the downstream transcription unit. This scenario is quite different from the one illustrated in Fig. 7. We think that two adjacent transcription units integrated into the same S. cereviaese genomic locus reduce DNA bending and, as a consequence, the competition between the RNA polymerase II molecules recruited by the insulator efficiency and other molecules targeting nearby DNA sequences. Each construct is labeled as tu1(CYC1) (i.e. the leftmost transcription unit that encodes for yomKate2 and ends with CYC1t) and the name of the insulator (if present) placed in front of the GPD promoter that drives yEGFP expression. Fluorescence levels are normalized with respect to the one expressed by pGPD on a single transcription unit. The * symbol indicates a statistically significant difference with respect to the wild-type pGPD fluorescence level