Laboratory Members
Microscopic view of the dorsal aspect and spine of a threespine
stickleback fish. Note the lack of melanophores and evidence of
petechial hemorrhage likely due to the physiological effects of a single
Schistocephalus (Psuedophyllidean: Cestode). |
Stella Richard, PhD student
Bio: I received my B.S. degree in 1992 from Arizona State University; an M.S. in 1994 from Arizona State University, and an M.A. in 1999 from Assumption College.
Research Interests: My work involves a detailed look into the physiology and microscopic morphology of the threespine stickleback. More specifically one of my projects involves morphological descriptions of the various chromatophores found in these fish. It is evident that melanophores (similar to melanocytes of humans) secrete the pigment melanin which creates the darkened black/grey color; erythrophores contain xanthines and are responsible for the reddish color seen in the males ventral surface during mating and nesting; and iridophores contain a purine substance that is a reflective silver color also seen in the fish. A unique color change is seen in some sticklebacks that cause them to lose their melanin pigment and become white while their eyes darken when infected with a single Schistocephalus (Psuedophyllidean: Cestode).
 |
Compare the completely darkened eye of a completely demelanized fish
(bottom) versus the eye from a partially demelanized fish. The darkening
of the eye is seen as an end result of demelanization. |
Microscopic evaluations of this color change may provide further evidence as to the mechanisms involved.
Another project involves the physiological signs these fish undergo following various stress conditions. Some of the stress conditions being studied include: reactions to individual fish when subjected to foraging groups, post stripping of eggs, and Schistocephalus parasite infections. Whole blood samples are collected via the caudal tail vein and used to detect the following: volume of blood extracted, packed cell volume (index for red blood cell percentage in whole blood, plasma color indices, blood smear evaluation by buffy coat prep/squash prep of whole blood, and cortisol levels. The data will provide answers to the significance of these stress events on the fish.
Significance: The threespine stickleback is an emerging model system (Gibson, Science 307, 2005) with outstanding potential for addressing the evolution of medically relevant developmental and physiological processes. The completion of the genome sequence this year in the threespine stickleback will further enhance its value. This research is a first step toward understanding how the stress response system evolves in threespine stickleback and potentially toward understanding variation in stress responses of humans.