McNair/Gateway Scholars Program USC

Martin Arredondo


Major and Classification

Human Biology

Faculty Mentor

  • Andrew Gracey, Ph.D.


  • Dornsife: Marine Environmental Biology

McNair Project

Effects of Temperature on Tidal Gene Expression Rhythms in Mytilus californianus

Mussels in the genus Mytilus are found worldwide and play an important role as a food source for a variety of invertebrates, fish, birds, and mammals. The dominant species on western coast of the U.S. is the Mytilus californianus, which must endure daily fluctuations in temperature, salinity, food and oxygen due to the constant ebb and flow of the tide. In addition to their circadian rhythms, marine organisms, especially those in the intertidal zone, also exhibit circatidal biological rhythms, with ~12.4 hour periods (Tessmar-Raible et al. 2011). However, the existence of a tidal clock has yet to be proven. In this experiment, we tested if gene expression patterns could be affected by only the environmental stressor of temperature. To study this, the organisms were kept completely submerged and did not experience the oxygen deprivation exhibited during tidal fluctuations. Using micro-array analysis, we investigated which genes are being affected by temperature in order to understand the fundamental mechanisms driving the physiology of this species. RNA from gill samples were extracted and pooled for PCR analysis every 2 hours for 48 hours, covering 4 high tides and 4 low tides. The mussels were kept completely submerged in an environment that fluctuated in temperature cycles that ranged between 16º C and 20º C.