I came to grad school to study Evolutionary Developmental biology; specifically what interests me is understanding how gene regulatory networks are modified over evolutionary time to generate new species and novel structures. I am probing this question using Mormyrids, a species-rich group of weakly electric fish. Mormyrids generate low levels of electricity (less than 1 volt) from their electric organ, and then sense this electric field on their skin with specialized cells; by monitoring distortions of their electric field these fish can locate and discriminate objects in their environment and communicate with their own species and discriminate other species.
The electric organ actually develops twice within the lifetime of a single individual. In the species I work with, Brienomyrus brachyistius, they develop a larval electric organ about a week after hatching. The electric signature of the larval electric discharge monophasic (very simple). During metamorphosis from fry into an adult, the fish begin to develop their adult electric organ in a different location from the larval electric organ. The electric signature from the adult organ is more specialized and complex than the larval organ and begins discharging while the larval organ is still active. Eventually the larval organ is completely lost and the adult organ becomes more complex through a specific change in anatomy (see figure for clarity).
Development of the larval and adult electric organs and the accompanying electric organ discharges in Brienomyrus brachyistius. A. Top to bottom. The larval electric organ differentiates from skeletal muscle in the body but is restricted from a region of the tail called the caudal peduncle. As the fish metamorphoses into an adult, the adult electric organ (AEO) develops and discharges simultaneously with the larval electric organ. Eventually the larval electric organ is lost and the adult electric organ fully matures and develops penetrations. B. Top to bottom: The electric organ discharges from a larval fish (note the simplicity), from a fish discharging from both a nearly degenerated larval electric organ (arrow, note small relative amplitude) and a non-mature adult electric organ, and from an adult, fully matured fish (arrowhead, note small, head-negative peak). Figure modified from Denzoit et al. 1978.
I intend to use loss of function studies to help me determine gene function. The technique I am most excited to be learning and excuting is CRISPR. CRISPR is a technique in which a specific region of the genome can be targeted for mutation; either to disrupt the gene and casue loss of function, to alter the sequence slightly, or to add new genes to the area. CRISPR is very versitle in that only a few conditions must be met in order to be properly executed. The organism of study should be accessible at the one cell stage for microinjections, and genomic sequence information should be available to produce targets. I am working on developing this technique in mormyrids as well as optimizing breeding and fry rearing in B. brachyistius. You can often find me at the microinjection scope at the EAGER facility in the basement of Natural Science.
Check out my first blog post (through BEACON, Dec 2016) to get a sense for some questions I hope to answer and how I intend to answer them. Stay tuned for more updates!
Denzoit et al., 1978. The larval electric organ of the weakly electric fish Pollimyrus (Marcusenius) isidori (Mormyridae, Teleostei). Journal of Neurocytology 7: 165-81.
van der Emde, 2006. Non-visual environmental imaging and object detection through active electrolocation in weakly electric fish. Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology 192(6): 601-12.