As a geneticist, I have an interest in the evolution of genes and how genes assume different and varied functions within developmental programs. We are currently characterizing members of a widely studied gene family, the nuclear receptor superfamily. This family of genes encodes transcription factors- under the influence of a hormone (or hormone-like) molecule these factors bind to DNA and regulate gene activity.

The invertebrate steroid hormone ecdysone is critical for growth in arthropods. Studies in insect systems have shown that ecdysone signaling, through nuclear receptor interactions, program the expression of genes critical to insect molting and metamorphosis.  Unlike many insects, which terminate growth when they emerge as adults, growth in crustaceans must be regulated in concert with reproduction, as well as with a specialized type of growth easily studied in crustaceans, limb regeneration.  We have isolated the genes encoding the components of the crustacean ecdysteroid receptor and have examined the expression pattern of these nuclear receptors during molt and reproductive cycles, and in regenerating limbs. How a "common" hormonal signal might modulate these varied physiological events is unclear, but different variants of the receptors have been identified, which have different physical properties relative to DNA and hormone binding. We also know the receptors are present on DNA, even when circulating hormone levels are low. 

We have recently shown that interfering with receptor signaling disrupts the earliest stages of limb regeneration- blocking cell division.  We are now using next generation sequencing technologies to identify genes expressed in normal tissues, and in tissues subject to knockdown of receptor expression.  We are hopeful that knowledge of the types and amounts of receptors present at different stages of growth and regeneration, coupled with targeted knock down of receptor function, will be able to allow us to identify putative receptor target genes in different adult tissues subject to hormonal control.

• Burnett KG, Durica DS, Mykles DL, Stillman JH, Schmidt C. Recommendations for Advancing Genome to Phenome Research in Non-Model Organisms. Integr Comp Biol. 2020 Aug 1;60(2):397-401. doi: 10.1093/icb/icaa059. PMID: 32497207.
• Das S, Vraspir L, Zhou W, Durica DS, Mykles DL. Transcriptomic analysis of differentially expressed genes in the molting gland (Y-organ) of the blackback land crab, Gecarcinus lateralis, during molt-cycle stage transitions. Comp Biochem Physiol Part D Genomics Proteomics. 2018 Dec;28:37-53. doi: 10.1016/j.cbd.2018.06.001. Epub 2018 Jun 15. PMID: 29940393.
• Shyamal S, Das S, Guruacharya A, Mykles DL, Durica DS. Transcriptomic analysis of crustacean molting gland (Y-organ) regulation via the mTOR signaling pathway. Sci Rep. 2018 May 9;8(1):7307. doi: 10.1038/s41598-018-25368-x. PMID: 29743490; PMCID: PMC5943448.