Spatial transcriptomics of C. elegans males and hermaphrodites identifies novel fertility genes

To advance our understanding of the genetic programs that drive cell and tissue specialization, it is necessary to obtain a comprehensive overview of gene expression patterns. Here, we have used RNA tomography to generate the first high-resolution, anteroposterior gene expression maps of C. elegans males and hermaphrodites. To explore these maps, we have developed computational methods for discovering region and tissue-specific genes. Moreover, by combining pattern-based analysis with differential gene expression analysis, we have found extensive sex-specific gene expression differences in the germline and sperm. We have also identified genes that are specifically expressed in the male reproductive tract, including a group of uncharacterized genes that encode small secreted proteins that are required for male fertility. We conclude that spatial gene expression maps provide a powerful resource for identifying novel tissue-specific gene functions in C. elegans. Importantly, we found that expression maps from different animals can be precisely aligned, which opens up new possibilities for transcriptome-wide comparisons of gene expression patterns.