Malaria is perhaps the most important parasitic disease worldwide, is caused the protozoan Plasmodium—P. falciparum causes the severest form of the human disease—and is responsible for half a billion cases of infection and up to 2.7 million deaths each year, most frequently in children. In the July 31 Sciencexpress, Karine Le Roch and colleagues at The Scripps Research Institute use microarray technology and statistical analysis and report the gene expression profiling of nine different stages of the parasite's life cycle, including human and mosquito stages. They observe that similar expression profiles of genes in particular tissues reflect similarity of function, providing direction for the analysis of the function of predicted hypothetical gene sequences (Sciencexpress, DOI:10.1126/science.1087025, July 31, 2003).

Le Roch et al. generated a microarray of 367,226 single-stranded 25mer probes from predicted coding and noncoding sequences that represented, on average, one probe every 150 base...