I’ve been neglecting this blog for a while, so I decided it was about time to start again. I am currently hanging out in Anacortes, Washington at the Shannon Point Marine Center, which is affiliated with Western Washington University. I am conducting research under an NSF/REU grant with one of the few labs on the west coast working on activated defenses of marine algae. More specifically, I am working under the researcher Kathy van Alstyne, observing pH changes in kelp as they undergo environmental stressors.
Several species of algae have been known to activate chemical defenses when dessicated and rehydrated. This cycle is meant to simulate the low tide, and in the lab is quantified as an 80% water mass loss. Dessication is deemed an appropriate stressor for testing these secondary metabolites, and the easiest to conduct in a lab.
Demarestia, a common brown algae, has been found to synthesize sulfuric acid in itsvacuoles. This is released into the surrounding water when Desmarestia is rehydrated. This sulfuric acid may drop the pH of the vacuoles as low as 0.5 pH units! (Pelletreau and Muller-Parker 2002)
Arguable one of the most well-researched, and interesting chemical compounds in algae is DMSP. Dimethylsulfiopropionate (phew!) is a useful osmolyte that can stabilize against slow changes in salinity. Under stress, DMSP lyase cleaves this compound into DMS and acrylic acid. Although DMSP has been shown to attract grazers, acrylic acid deters them, which puts it on the map as a potential activated defense system. (Alstyne et al 2001)
One of the more recently discovered defense systems is the synthesis of dopamine in Ulvaria, a green algae. Dopamine is a common neurotransmitter in many organisms (including humans!) and actively deters feeding by sea urchins in this algae. Dopamine also lowers the pH of the water around it.
As mentioned before, the study of secondary metabolites in temperate algae is not very extensive at this point. Some preliminary research at Dr van Alstyne’s lab suggests that there may be pH drops (a possible sign of activated defenses?) in previously unresearched local species. My job over the summer is to attempt to observe pH drops, ex situ (in the lab) and in situ (in the field). I will be bringing pH probes into algae beds as the tide rises, looking for a drop in pH from the exuded defenses. I will also be rehydrating species of algae in the lab, looking for pH drops not only in the cells but in the water surrounding them.
Pictures to come! hopefully this is a comprehensive introduction to my life here at Shannon Point for the summer.