Yeast Cells (IMAGE) Proceedings of the National Academy of Sciences Caption These are yeast cells expressing bioluminescence-related genes from fungi growing in a medium containing caffeic acid. Credit Image courtesy of Sergei Shakhov (photographer). Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.