cDNA libraries from identified neurons.

One approach to studying the changes in gene expression which underlie differentiation is to construct cDNA libraries from different tissues or at different stages of development. However, generating representative cDNA libraries from heterogeneous tissues such as the nervous system is often a real problem. Here, we describe a reproducible method for the construction of large and complex cDNA libraries from a few leech Retzius or P neurons (equivalent to about 50 pg of mRNA) using polymerase chain reaction-based technology. The libraries contain about 10(6) independent recombinants and are remarkably free from contaminating rRNA or polymerase chain reaction artefacts. Sequence analysis of randomly picked clones shows that the libraries contain a high proportion (more than 90%) of cDNAs larger than 500 b.p. As expected, many of the clones are novel, but two (alpha-tubulin and cyclophilin-A) have been extensively characterized in other species. To our knowledge, this is the first report of a cDNA library from identified neurons.