Molecular Mechanisms for Adaptation in a Plant Species Native to Urbanized Estuaries

Friday, February 12, 2016
Ryan Berger, The Lisman Labs at Riverdale Country School, Bronx, NY
Populations undergo an array of changes when subjected to stress. The Bronx River is an urban waterway with a history of factory waste and sewage dumping and unusually high Benzo-a pyrene concentrations. Over a seven-year study, we documented low dissolved oxygen concentrations as well as endocrine disruption in the native ribbed mussel population. Effects of these stresses on the physiology of the foundational species Spartina alterniflora (smooth cordgrass) were measured in comparison to the relatively less impacted Greenwich Cove. As sessile organisms, grasses are forced to rapidly counter stress. Heat shock protein 70 (HSP70) expression is launched  more quickly and with a smaller response in Bronx S. alterniflora than in Greenwich Cove, suggesting a state of constant readiness in the Bronx. We analyzed global methylation as well as comparative protein expression for HSP70, RAD51, and BiP, in response to abiotic stressors: heat, salt, and hypoxia. Our results find differences in baseline as well as acute responses in organisms from our two study sites. Further alterations to methylation and protein expression in reaction to abiotic stress indicate differential intraspecies responses at the level of gene regulation. These insights provide information on mechanisms of long term adaptation to urbanization in this foundational sessile estuarine species.