Stressed out Seaweed


Killian Campbell, Eastern Washington University


In my last post, I introduced you to Gracilaria vermiculophylla (the invasive seaweed that I’m studying this summer) and the certain qualities it possesses that make it an interesting organism to study. I also mentioned that I am investigating the role of heat shock proteins (Hsps) in Gracilaria and how they potentially play a role in allowing Gracilaria to survive in different types of environments. However, I did not speak about the ways that I am going to actually understand those processes.

To put it plainly, I am stressing out my seaweed. Big time. In a biological context, this means that I am subjecting the Gracilaria samples to different conditions that it does not typically experience in the wild. As a result, the conditions that it will experience in the lab will be uncomfortable for the organism, and will thus produce “stress” in the organism.


Fig. 1: Gracialaria samples in the incubator for storage after receiving stressors

In my project, the stressors we are choosing to subject Gracilaria to are: extremely hot and cold water temperatures, and extremely low salinity levels. After subjecting Gracilaria to these stressors, we will be looking for the amount of bleaching that occurs in the samples. Bleaching is an indication that the conditions the sample is experiencing are too stressful. Bleaching is a loss of pigment in the seaweed (turning from dark red to light pink or white) and it is similar to when leaves on a tree dry out, change colors and fall off—In other words, it is an indication of death in photosynthetic organisms. The data generated from these tests will tell is the types of stressors Gracilaria can endure, and how long it will take to produce a bleaching response in the Gracilaria afterwards.


Fig. 2: 12-well plate with each well containing Gracilaria tips plucked from different individuals. For each tip, a specific stressor was applied to it.

To assess the importance of heat shock proteins in enduring various stressors, we will repeat the parts of the study above, except that we will also administer inhibitors to the Gracilaria samples this time.  Inhibitors are chemicals that stop the function of heat shock proteins. In theory, giving inhibitors to Gracilaria should decrease their ability to endure stressors.

As a result of the studies, we are curious to see if the data demonstrates that heat shock proteins confer a higher amount of stress tolerance in Gracilaria. By further understanding the role of Hsps in Gracilaria, we can begin to understand their greater ecological role. This may encourage future studies to develop knowledge about the role of Heat shock proteins play in allowing invasive organisms (such as Gracilaria) to inhabit so many diverse environments!


Thank you to Dr. Erik Sotka, Benjamin Flanagan and everyone else in the Sotka lab. I would also like to thank Grice Marine Laboratory at the College of Charleston and the NSF for this wonderful opportunity


Literature Cited:

Feder, M. E., and Hofman, G. E. (1999). HEAT-SHOCK PROTEINS, MOLECULAR CHAPERONES, AND THE STRESS RESPONSE: Evolutionary and Ecological Physiology. Annual Review of Physiology. 61, 243-282.

Flanagan, B., Kreuger-Hadfield, S., Murren, J., Sotka, E. E., and Strand A., (Unpublished) Increased heat tolerance and heat-shock protein expression in non-native range of a widespread marine invader

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