Meeting Abstract
The Y-organ (YO) is an endocrine gland responsible for cyclic ecdysteroid biosynthesis, regulating molting. In the crab “” G. lateralis ““, molt entry can be triggered by: 1) eye-stalk ablation (ESA), leading to loss of molt inhibiting hormone (MIH); 2) multiple leg autotomy (MLA), where limb loss coordinates regeneration with new growth/cuticle deposition. Although mTOR and TGF-Beta signaling pathways have been previously identified in molt cycle progression, other signaling cascades driving the production/inhibition of ecdysteroid biosynthesis are largely unknown. To examine gene expression patterns consequent to molt induction, molt entry was induced by both ESA and MLA and YOs processed for RNA-seq at different temporal intervals. Circulating ecdysteroid titers were determined at the time of tissue collection. For both ESA and MLA datasets, the differential expression pipeline included removal of low counts; normalization of count data using RUV-Seq, and identification of differentially expressed (DE) contigs using edgeR. Following filtering and normalization, 35696 (ESA) and 48590 (MLA) contigs were assembled. These contigs were used to identify 8706 (ESA) and 14791 (MLA) DE contigs at a <0.01 FDR cut-off. BLASTx against the KEGG Ortholog (KO) database using human and 6 insect species resulted a total of 878 (MLA) and 464 (ESA) annotations with KO relevant to 23 (MLA) and 24 (ESA) signal transduction pathways. mRNA levels for the genes representing KEGG signaling pathways, including MAP kinase, mTOR, cAMP and Wnt were identified as significantly enriched at a <0.05 FDR cut-off, implicating a role in regulating molt cycle stage transitions. Identification of pathway differences between the two molt-induction methodologies is in progress. Supported by NSF (IOS-1257732).
