Table S1.xlsx from Head transcriptome profiling of glossiphoniid leech (<i>Helobdella austinensis</i>) reveals clues of proboscis development

Cephalization refers to the evolutionary trend toward concentration of neural tissues, sensory organs, mouth and associated structures at the front end of bilaterian animals. Comprehensive studies on gene expression related to anterior formation in invertebrate models are currently lacking. In this study, we performed <i>de novo</i> transcriptional profiling, on a proboscis-bearing leech <i>Helobdella austinensis</i> to identify differentially expressed genes (DEGs) in the anterior versus other parts of the body, and in particular to find clues as to the development of the proboscis. Between the head and the body, 132 head-specific DEGs were identified, of which we chose 11 to investigate their developmental function during embryogenesis. Analysis of the spatial expression of these genes using <i>in situ</i> hybridization showed that they were characteristically expressed in the anterior region of the developing embryo, including the proboscis. Our results provide information on genes related to head formation and insights into the function of proboscis-related genes during organogenesis with the potential roles of genes not yet characterized.