Towle 9807539 Euryhalinity, the ability to tolerate a breadth of environmental salinities, is a property of a small number of plant and animal species. However, some euryhaline species may be very prolific, exemplified by the blue crab in the Chesapeake Bay. The PIs goals are to discover the molecular mechanisms that enable euryhalinity, focusing on a group of closely related animals that exhibit an array of adaptations to salinity. The blue crab Callinectes sapidus is itself extremely euryhaline, thriving in fresh water and lagoons more concentrated than normal sea water. Its close relative, Callinectes similis, however, cannot survive dilute salinities. The PIs will study these plus a third intermediate species, the green shore crab Carcinus maenas, to describe the genes and proteins that make euryhalinity possible. The PIs will focus on three candidate transporter proteins that may regulate the uptake of sodium by the gill. The PIs hypothesis is that the genes coding for important proteins will be active in tolerant species but inactive or less active in intolerant species. All of the candidate transporter proteins have been implicated in salt handling by kidneys of mammals and other vertebrates. If the PIs are able to demonstrate salinity-related activation of one or more of the transporter genes, the PIs will embark on a search for the hypothetical regulatory "sodium uptake response element" ("SURE").
