Research


Embryos

As a geneticist, a major career interest has been an examination of the organization and evolution of gene families, and changes in the function and regulation of evolutionarily related genes during invertebrate development. Our current research uses crustaceans- specifically crabs and shrimp- to investigate the role of hormone signaling in the processes of growth, reproduction, and development. All three of these processes are regulated through changes in steroid and terpenoid hormone concentrations over the animal’s growth cycle. These organisms are especially interesting in that they must shed their hard external skeletons in order to grow; the fancy word for this molting process is termed ecdysis, and is mediated by a class of steroids termed ecdysteroids. Superimposed on this molting cycle is the remarkable ability to regenerate limbs.  When a crab is actively feeding in an intertidal zone, it is subject to predation. If a limb is grabbed during an attack, the crab can reflexively shed that limb and regenerate a new one over the course of the molt cycle. Loss of multiple limbs can accelerate the molt cycle. Our lab is currently involved in:

 

1) The characterization of gene pathways involved in regulating the cyclicity of ecdysteroid hormone synthesis in crustaceans. Our most recent publication, examining the role of the mTOR regulatory pathway on molt cycle signaling, can be found here.

 

2) The role of nuclear receptor signaling in the developmental programming of the process of regeneration.

 

3) The role- and possible intersection- of the terpenoid signaling pathway with ecdysteroid signaling during growth, regeneration and reproduction. Terpenoid hormones have been actively studied in insect growth, where they mediate the developmental transition from larva to adult. They are required for reproduction in crustaceans and are also implicated in molt regulation.

 

4) Development of a model system where recent methodologies for generating gene knockdown and mutation can be employed to study the above hormone signaling pathways. One promising model is a common aquarium pet, the freshwater cherry shrimp.

 

For a broader description of each of these lines of investigation, please visit the subpages in the research section by clicking on the above links (red).