Completed Projects

Doctoral research

I continued to work with hydrogen sulfide during my doctoral studies with David Julian (University of Florida). We determined that exposure to sulfide induces an oxidative stress response in an aquatic invertebrate that is not sulfide-tolerant (the bivalve, Donax variabilis, pictured to right). These clams live on high energy sandy beaches where they likely are not exposed to sulfide. When the clams were brought into the lab and exposed to relatively low levels of sulfide for several days, they upregulated their expression levels of several stress proteins that are indicative of an oxidative stress response. These results suggest that the sulfide can alter free radical metabolism.

Joyner-Matos, J, Downs, CA, and Julian, D. 2006. Increased expression of stress proteins in the surf clam Donax variabilis following hydrogen sulfide exposure. Comparative Biochemistry and Physiology 145:245-257.

In another project, we explored whether functional and cellular-level biomarkers can be useful in determining the health of the stress tolerant bivalve, Mercenaria mercenaria (pictured to the right). These clams are an important aquaculture species in several states, including Florida. Southern Cross Sea Farms Inc. in Cedar Key, FL generously donated the clams for this study and us on several excellent tours of the hatchery (see picture of the Mercenaria group with Bill, the guru of all things clam).  Several undergraduate students participated for multiple years in this study, including Jenessa Andrzejewski, Laura Briggs, Jennifer Rivas, and Michaela Hogan, all of whom continued on to multiple graduate/clinical degrees!

Joyner-Matos, J, Andrzejewski, J, Briggs, L, Baker, SM, Downs, CA, and Julian, D. 2009. Assessment of cellular and functional biomarkers in bivalves exposed to ecologically-relevant abiotic stressors. Journal of Aquatic Animal Health, 21:104-116.

We also explored the physiology of the marine annelid Glycera dibranchiata (pictured to right). These worms are collected from sulfidic mudflats along the northeastern Atlantic coast. In a recent study we found that worms exposed to ecologically relevant sulfide levels had elevated levels of free radical production in their coelomocytes ("blood" cells) and elevated oxidatively damaged DNA and RNA in their body wall tissue and coelomocytes. Early Glycera work was conducted with Rajat Bhalla while he was a high school student participating in the UF Student Science Training Program (Rajat was a semifinalist in the 2003 Siemens Westinghouse competition and the 2004 Intel Science Talent Search with this project, now recently graduated from MIT and applying to medical school).  Sulfide work was conducted with Jenny Stein (undergraduate student at UF, now employee of a biotech firm) and Ben Predmore (now a postdoc at Emory).

Joyner-Matos, J, Predmore, BL, Stein, JR, Leeuwenburgh, C, and Julian, D. 2010. Hydrogen sulfide induces oxidative damage to RNA and DNA in a sulfide-tolerant marine invertebrate. Physiological and Biochemical Zoology. 83:356-365.

Joyner-Matos, J, and Julian, D. 2011 Oxidative Stress in Sulphidic Habitats. In: Oxidative Stress in Aquatic Habitats, T Zenteno-Savin and D Abele (Eds). Wiley Blackwell Publishers. Link to Wiley's web page for our book.