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RESEARCH AT UAS

I consider myself a comparative physiologist who maintains a focus on the organism. I take a reductionist approach to the study of crustacean physiology as my research is focused primarily on hormonal regulation of growth and reproduction in commercially important crabs. Some of the many crabs I work with include king crab, Paralithodes camtchaticus, snow crab, Chionoecetes opilio, Tanner crab, C. bairdi, and Dungeness crab, Cancer magister. Growth is a periodic process that requires the shedding of the old exoskeleton, a process regulated by hormones. The primary molting hormones are ecdysteroids that are compounds derived from cholesterol and some of these play a role in crustacean development and reproduction as well. Ecdysteroids are synthesized throughout the life cycle of crustaceans. The specific ecdysteroid that promotes growth is 20-hydroxyecdysone and is derived from the steroid precursor ecdysone, which is a product of a well defined endocrine gland. The synthesis and secretion of this hormone is highly regulated during development, reproduction and growth. I am interested in environmental and physiological factors that regulate ecdysteroids since factors that influence the synthesis and metabolism of this hormone will therefore have multiple physiological effects dependent upon the life history of the organism. Although my studies involve studying crustacean physiology at the level of the cell, I am most interested in relating this information back to the whole organism.

Most recently, I have been taking endocrinology to the field and my students utilize SCUBA and boat charters to collects their animals for study. Through field studies, we are able to learn more about physiological dynamics within a population. We can learn when cohorts of crabs are molting and about the reproductive physiology of females .

Ji m Taggart (USGS)

GRADUATE AND UNDERGRADUATE STUDENTS

PUBLICATIONS

Research Experiences For Undergraduates (REU)

Students are chosen from a large pool of applications to experience both field and laboratory research at the University of Alaska Southeast. The students that I choose for my projects work primarily in the laboratory and utilize biochemical techniques to measure inverterbate hormones. These student research experiences are supported by a grant awarded to Dr. Brendan Kelly and Elizabeth Mathews from the National Science Foundation (NSF)

Past REU Projects

Past Projects in my Laboratory

1. Effects of temperature on reproductive hormones in the snow crab, Chionoecetes opilio. Using biochemical assays (ELISA and HPLC) we are measuring circulating ecdysteroids and methyl farnesoate in female snow crabs maintained at different temperatures. This research is supported by the Alaska Department of Fish and Game

2. Hormonal regulation of molting of snow crab, Chionoececetes opilio. We are seeking to determine via endocrinological methods whether male snow crabs undergo a terminal molt. This work was supported through the Alaska Department of Fish and Game

3. Reproductive biology of the Dungeness crab, Cancer magister. This research is both a field-based and a laboratory based study on the feasability of using hormone assays to determine reproductive status of C. magister in Glacier Bay. This research will be applied to populations of C. magister in other regions of Alaska. This research is supported in part from the Alaska Sea Life Center.

4. Effects of environmental chemicals (endocrine disruptors) on steroid hormone metabolism. This research uses the dungeness crab as a model for steroid hormone biology. We are looking at the effects of certain persisitant pollutants on the regulation of steroid hormone synthesis and the regulation of steroid dependent gene transcription. This research is supported by a grant awarrded through the Alaska Biomedical Research Infrastructure Network BRIN now INBRE

SOME PHOTOGRAPHS FROM THE FIELD

Glacier Bay

Dutch Harbor

Southeast Alaska