Cellular Tagging by Means of Learning and Estrogenic Signaling in the Mouse Brain

This project aims to determine the identities of cells recruited by learning, estrogenic signaling, and their combination in the dorsal hippocampus (DH), which mediates object identity and spatial memory. Male and female mice will be gonadectomized and infused with an activity-dependent virus. Prior to training in object placement (OP) or object recognition (OR) tasks, viral expression of the fluorescent marker, eYFP, will be induced for cells active during learning, estrogenic treatment, or both, tagging those cells. Mice will be infused with vehicle or 17-estradiol (E2) immediately following OP or OR training or control homecage handling and will have their tagging windows closed immediately thereafter. Mice will have their brains collected 90 minutes following memory testing or control handling and immunohistochemically labeled for the immediate early gene marker of cellular activity, c-fos, as well as GAD67, VGLUT1, and GFAP as markers of inhibitory neurons, excitatory neurons, and astrocytes, respectively. Co-localization of eYFP, c-fos, and GAD67, VGLUT1, and GFAP will show which cells in the DH were activated during training, infusion, and memory recall. These results will be critical in determining how the neuromodulator, E2, affects learning processes at a cellular level, allowing for subsequent molecular investigations in a cell-specific manner.

Motion Analysis Support

This study is being conducted in conjunction with a team at MCW working on developing a dynamic MR imaging methodology. We conduct gold-standard motion analysis testing to validate the MR imaging data. This involves placing reflective markers on the participant's hands, arms, and upper body, collecting motion capture data while participants conduct specific movements, and collecting measurements of a few segments of the participants arms and hands. Once the data are collected, they must be processed and analyzed before sending results to the MCW team to compare to their data.

Measurement of Purines in Cichlid Fish

The aim is to determine the molecular and cellular causes of the color of a new breed of bony fish produced by our colleague. He recently cross-bred two species of genus Labeotropheus which produced hybrid offspring whose color was affected by parental gender. One hybrid has a unique color and it was found the color of this novel hybrid animal is associated with an increase in its ability to reflect ultraviolet light. Four pigment molecule types (chromatogens) and skin pigment cell types (chromatophores) are known to be responsible for the myriad of colored appearances of many phylogenetic groups of vertebrates, including several types of bony fish, but not for Labeotropheus or any other genus in this family, Cichlidae. The pigments most likely responsible for the color of the novel hybrid cichlid are the purines, guanine and hypoxanthine, which absorb ultraviolet light and form crystals that reflect visible light. They are normally present in iridophore cells in skin. In this project we will extract prurines from iridophores isolated from the novel fish breed and from normally colored fish, and measure the guanine and hypoxanthine content of the extracts.