In the field of synthetic biology, Genetic memory devices have been constructed and applied widely from Biocomputing to biomedical technologies as a crucial component. Such memory devices include a cellular counter; a fundamental device which memorizes the number of induction events. Recent efforts have resulted in a cellular counter that can count up to three events. However, this counter cannot be reset to its initial state. Here, we propose a resettable cellular counter called “sigma recounter”. This counter utilizes the regulation system of sigma factor and anti-sigma factor as the key of its resetting mechanism. In this system a set of sigma factors are designed to update and maintain a count that responds to each inducted event. By the other stimulus, the system initiates a genetic circuit that can express a suitable set of anti-sigma factors and erases the existing memory, which will enable our device to restart the count from any state.
Circulating Tumor cells (CTCs) are tumor cells derived from primary cancerous tissues and flowing through blood vessels. By detecting CTCs, it can be attained to find early-stage cancer. In the present efforts of detecting CTCs, markers used to distinguish CTCs from other types of cells have been restricted to cell surface proteins. On the other hand, by introducing genetic circuits into cells, we can utilize intracellular molecules such as RNAs and proteins. Here, we developed a new method focusing on both EGP-2 promoter, which is highly activated in CTCs, and miRNA, which is expressed and inhibits the translation of mRNA only in hematopoietic cells. By combining these two markers, our method would achieve detecting CTCs with high accuracy.