Rescued Mutant
Kelly Grant (UCD)

Cell transplants, fluorescent microscopy, Adobe Photoshop
The lateral line is a sensory organ of aquatic vertebrates that detects vibrations. We study the lateral line because it is highly similar to the ear, but more accessible for experimentation. In the ear, specialized, ciliated cells allow us to hear. The lateral line has the same ciliated cells, except they are found in clusters, called neuromasts, along the fish's body.

We discovered a population of stem cells that generates neuromasts. Surprisingly, we found that glial cells, cells that insulate nerves, prevent the neuromast stem cells from proliferating. Without glia, the stem cells precociously divide and differentiate, generating too many neuromasts.

This is a living, mutant, 4 day-old fish that had "surgery". Without surgery, this fish would lack glia and have too many neuromasts, but when this fish was 6 hours old (at that point just a bunch of cells) I took cells from a younger, healthy, donor embryo and transplanted the cells into the mutant. The transplanted cells differentiated into glia and ensheathed the lateral line nerves that innervate each neuromast (large yellow spots). The glia are marked with Green Fluorescent Protein (GFP), because the donor cells have a transgene that turns on GFP in glia. The embryo has been stained with a yellow dye, DASPEI, which gets taken up by the ciliated cells in the neuromasts. The transplanted glia restored normal regulation of the stem cells. The big, black, round spot is the fish’s eye, the ear is to the right of the eye. The black stripes of the zebrafish can be seen on the top of its head and behind and right of the ear.

We hope that our findings might help doctors learn how to grow new ciliated cells in the human ear to eliminate age-related hearing loss and certain forms of deafness.