[46]

Small Satellite Platform for Automated Gene Expression Measurements.    A. Pohorille¹, A. J. Ricco^1,3, A. McShea², D. Danley² and K. Schweighofer^{1,4 1}NASA-Ames Research Center, ²CombiMatrix Corp., ³Stanford Univ. and ⁴Univ. of California Santa Cruz.

   We have been developing a fully automated, miniaturized system for measuring gene expression of microorganisms on small spacecraft. This low-cost, multi-purpose instrument will represent a major scientific and technological advancement in our ability to study the impact of the space environment on biological systems using small satellite platforms by providing data on cellular metabolism and regulation orders of magnitude richer than what is currently available. The system will support growth of the organism, lyse it to release the expressed RNA, label the RNA and read the expression levels of a large number of genes by microarray analysis of labeled RNA. Microarray technology developed by CombiMatrix is based on electrochemical reactions on arrays of electrodes on a semiconductor substrate. Since the electrical integrity of the microarray remains intact after probe synthesis, the circuitry can be employed to sense nucleic acid binding at each electrode. CombiMatrix arrays can be sectored to allow multiple samples per chip. In addition, arrays can be readily reused at least 4 Helvetica,Arial,sans-serif. This means that a single array can be used for many assays. The array has been integrated into an automated microfluidic cartridge that uses flexible reagent blisters and pinch pumping to move liquid reagents between chambers. Preliminary studies indicate that this cartridge is as good as or better than manual processing methods for microarray analysis. We are currently working on integrating this cartridge with a multi-chamber subsystem for detection of gene expression levels using dried reagents already developed by Micronics. The assay methodology for harvesting bacteria from micro/mesofluidic cartridges has been developed for the GenSat-1 program along with a sample preparation module, also developed by Micronics, to extract the mRNA from bacteria.