Jonathon H. Stillman University of Hawaii at Manoa Understanding the plasticity and limits of physiological responses to changes in temperature is a key component to understanding how global climate change will impact species distribution and abundance patterns. The aim of this project is to combine functional genomics and cardiac physiology to study the physiological responses of intertidal zone porcelain crabs to environmentally relevant temperature changes. Marine intertidal zone organisms experience changes in habitat temperature over both long (e.g., seasonal) and short (e.g., daily) time scales. This research will characterize physiological acclimatization to seasonal changes in habitat temperature and physiological stress responses following acute temperature changes during a low tide period, both of which are important components of the thermal responses of organisms in their natural habitat. Four specific questions will be addressed: 1) What genes are involved in setting cardiac thermal performance limits?, 2) Does thermal acclimation influence responses to acute thermal stress?, 3) What gene expression and thermal physiology changes occur during acclimation to fluctuating temperatures?, and 4) Does response to acute thermal stress vary across seasons? To answer question #1, crabs will be sampled during a one-month acclimation to three temperatures (6C, 14C, and 22C). Sampling will consist of in vivo determination of upper and lower thermal limits of cardiac function (CTmax and CTmin, respectively), and analysis of heart tissue transcriptome profiles using a custom microarray consisting of 13,824 cloned P. cinctipes cDNAs. To answer question #2, crabs acclimated to those three temperatures will be exposed to an acute heat, cold, or control stress and transcriptome profiles during recovery from those stresses will be analyzed. To answer question #3, crabs will be acclimated for one month to a thermal regime that includes a brief daily exposure to extreme heat or cold (-1C and 30C), after which time CTmax, CTmin and transcriptome profiles will be analyzed during four cycles of the acclimation. To answer question #4, crabs will be sampled from their natural habitat across the seasons of one year and CTmax, CTmin, and transcriptome profiles of field and stressed crabs will be measured during each season. Statistical analysis of transcriptome profiles using microarray ANOVA will reveal which genes have significant changes in expression in each of the four experiments. The data generated in this project will be made publicly available on the Stanford Microarray Database. This research will generate novel hypotheses in fundamental areas of animal physiology, namely the molecular bases of thermal limits, eurythermality, and thermal acclimation. The results of this work will directly inform comparative functional genomics studies of temperature adaptation in porcelain crab congeneric species from a range of thermal habitats across a wide range of biogeographic regions. Thus these data will contribute to our understanding of how global temperature change influences species range distributions. Undergraduate students from Hawaiian and Pacific Islander underrepresented minority groups will be recruited to work on this project through the University of Hawaii's Haumana Minority Access to Research Careers (MARC) programs. Benefits to graduate and undergraduate students involved in this research include the development of laboratory and professional skills, and exposure to the "mainland" scientific community at professional meetings and during summer field-work at the Oregon Institute of Marine Biology.
