Meeting Abstract

P2.18  Monday, Jan. 5  Skeletons Out of the Closet: Insight to Food Resource Related Phenotypic Plasticity in the Sea Urchin, Strongylocentrotus purpuratus, via Multiplex Gene Expression Profiling FIELMAN, K.T.*; UEDA, N.; Auburn Univ.; Auburn Univ. fielman@auburn.edu

Phenotypic plasticity in urchin larval morphology is a well-documented developmental response to differences in food resources. When food resources are poor, the larval skeleton enlarges to increase the surface area for particle capture. Underlying this phenomenon is the genetic network responsible for growth. Here, we unite larval feeding ecology and molecular development by quantifying expression of growth-related genes from larval urchins reared under contrasting food regimes. We developed a multiplex qPCR assay covering 34 different urchin transcripts and used it to contrast expression in fed and unfed plutei over time. We detected transcripts for multiple spicule matrix protein families and proteins associated with cell migration and rearrangement, cell signaling pathways, and fundamental metabolic genes. Consistent with their increased skeletal growth, unfed plutei showed strong transcriptional up-regulation of BMP5(7/8), spicule matrix proteins MSP130(5)/SM30(A), thyroid hormone receptors, and tetraspanin. These genes were all down-regulated in fed plutei. Unfed plutei also had up-regulation of spicule matrix proteins SM30(D)/(F) and P16, and a carbonic anhydrase not present in fed larvae. Furthermore, fed plutei showed down-regulation of advillin, collagens and the spicule matrix proteins P19 and PM27, that were not present in unfed animals. Finally, unfed plutei had up-regulated ubiquitin but down-regulated EF1a transcripts relative to their fed counterparts. Collectively, these transcriptional-level, unique signatures of enhanced skeletal growth in urchin plutei open a direct path to our forthcoming, more detailed ecological and molecular-level developmental studies.