Meeting Abstract
Understanding why a diversity of regenerative potential exists throughout the animal kingdom remains a major question in biology. In our lab we use the colonial hydrozoan Hydractinia, which is capable of fully regenerating a feeding polyp’s head in about 72 hours. This dramatic process is orchestrated by migratory adult stem cells, known as interstitial cells (or i-cells). Cell proliferation and blastema formation are two essential steps of head regeneration in Hydractinia. To analyze the genes involved in this process, we extracted the mRNA of presumptive blastema tissue (upper body column) from feeding polyps whose heads had just been removed as well as blastema tissue at 24 hours after head removal, and we performed RNAseq and differential expression analyses. We found 2438 transcripts differentially expressed in blastema tissue at 24 hours, with 1246 transcripts downregulated and 1192 upregulated compared to control tissue. We chose a subset of these genes, many of which are differentially expressed during head regeneration in Hydra, another highly regenerative hydrozoan, and carried out qPCR analysis. The results we obtained validated the RNAseq data and led to the observation that similar gene networks are used in head regeneration among hydrozoans. We are also performing in situ hybridization on a number of genes to characterize their spatial expression during homeostasis and regeneration. This study provides an overview of gene expression during head regeneration in Hydractinia, and enables present and future comparisons of the gene networks used by different animals throughout regeneration.
