ANALYSIS OF GENE-EXPRESSION IN SINGLE LIVE NEURONS

We present here a method for broadly characterizing single cells at th e molecular level beyond the more common morphological and transmitter /receptor classifications. The RNA from defined single cells is amplif ied by microinjecting primer, nucleotides, and enzyme into acutely dis sociated cells from a defined region of rat brain. Further processing yields amplified antisense RNA. A second round of amplification result s in > 10(6)-fold amplification of the original starting material, whi ch is adequate for analysis-e.g., use as a probe, making of cDNA libra ries, etc. We demonstrate this method by constructing expression profi les of single live cells from rat hippocampus. This profiling suggests that cells that appear to be morphologically similar may show marked differences in patterns of expression. In addition, we characterize se veral mRNAs from a single cell, some of which were previously undescri bed, perhaps due to "rarity" when averaged over many cell types. Elect rophysiological analysis coupled with molecular biology within the sam e cell will facilitate a better understanding of how changes at the mo lecular level are manifested in functional properties. This approach s hould be applicable to a wide variety of studies, including developmen t, mutant models, aging, and neurodegenerative disease.