The Science Unit is focused on designing the research mission, namely the satellite payload, comprised of the yeast model and the micro-instrumentation necessary for the realization of the mission goals. Towards that objective, members of the interdisciplinary team work on the following:
Genetically engineering yeast cells to emit fluorescent signals as markers of gene expression and DNA damage
To that end, we are using the Yeast GFP Library, which is a collection of yeast strains identical to each other except that in each strain a different protein is tagged with a fluorescent protein (GFP), covering overall the entire yeast proteome. This tagging method is complemented with , a systematic approach to identify the candidate genes to be studied. To study radiation, the team is re-engineering a previously used DNA damage memory circuit. This is a synthetic circuit that essentially “hijacks” the cell’s DNA damage signalling cascades to actuate a positive feedback loop leading to the production of a second fluorescent protein of a different color, eventually identifying the cells in which mutations have occurred along with their progenies, thus enabling comparisons of protein levels between healthy and damaged cells.
Utilizing a microfluidic chip and a respective micropump system, as the necessary instrumentation for the continuous growth of cells in orbit
To accommodate the concurrent growth of multiple Library strains, we are implementing a microchemostat array similar to the one described here. Solenoid valves and micropumps are used to prime the control layer and to control the flow of sterilized growth medium along the bottom flow channels. Sterilized growth medium and waste are stored in medical-grade, sterilized polyethylene vinyl acetate (PEVA) bags. The team is also working to increase control lines’ redundancy in the chip designs.
Designing a miniaturized fluorescence microscope
A dual-channel digital microscope, modified from existing models used to perform optical recordings of neural activity in walking mice, is designed to measure the fluorescence intensity of each microchemostat’s population.
Ensuring the essential conditions for cell growth in space
To withstand launch conditions and achieve long-term storage, sporulation of yeast cells is employed. The experiment is taking place in a pressurized vessel (1 atm), which takes up the space of almost 2 units and will run at 3 distinct time-points. A number of sensors are in place inside to measure CO2, pressure, temperature and humidity. The temperature required for optimal yeast growth is 30 ºC and is achieved by a polyimide based heater on the bottom surface of the chip.