The Science Unit is tasked with designing the research mission, i.e. the satellite payload, comprised of the yeast cells to be studied 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 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 fluorescent protein, eventually identifying the cells in which mutations have occurred along with their progenies.

Engineering a system-compatible microfluidic continuous culture system, composed of a microfluidic chip, micropumps and assorted paraphernalia

To accommodate the concurrent growth of multiple Library strains, we are implementing a  biodisplay 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.

Microfluidic_Chip
Microfluidic chip, as fabricated by the team in LBNC, EPFL

Designing and fabricating a miniaturized fluorescence microscope

A epifluorescence 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 chamber’s population.

Microscope
Fluorescence microscope for cell imaging

Ensuring the essential conditions for cell growth in space

To withstand launch conditions and achieve long-term storage, sporulation of yeast cells is performed. 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.