The chemoreceptor genes of the waterflea Daphnia pulex: many Grs but no Ors.

Background: Chemoreception is vitally important for all animals, yet little is known about the genetics of chemoreception in aquatic organisms. The keystone species Daphnia pulex, a well known crustacean, is the first aquatic invertebrate to have its genome sequenced. This has allowed us the initial investigation of chemoreceptor genes in an aquatic invertebrate, and to begin the study of chemoreceptor evolution across the arthropod phylum.

Real-time assessment of fluid flow generated by appendage movements of Daphnia using standing square-wave chronamperometry.

Standing square-wave chronoamperometry (SSWCA) was applied to the analysis of the microfluid flow generated by the movement of the appendages of the Crustacea Daphnia. This novel approach provided for the first time real-time assessment and analysis of the breathing rate/fluid flow of individual organisms. An electrochemical tracer was delivered into the fluid inflow of the organism and a carbon fiber microelectrode placed in the fluid outflow's path.