Dr. John Freeman
Chair and Professor, Department of Biological Sciences
University of South Alabama
Ph.D., 1978, Duke University, North Carolina

Research Description:
We are currently involved in two aspects of crustacean larval development:

The mechanism of growth of the epidermis and muscle

Cellular basis of limb development and epidermal cell morphogenesis

In particular we are investigating the cell cycle of epidermal cells in crustacean larvae to compare the growth patterns in developing and nondeveloping regions and to define the mechanism by which the cell cycle phases are regulated by nutrients.

Another area of interest is the interactive growth of muscle and the modified epidermal cells that attach them to the cuticle. Ongoing studies are aimed at determining whether the tendinal cell is active in controlling growth of the muscle. A third area of interest is the mechanism of control of differentiation of epidermal cell types and integumental structures during the larval period.

Representative Publications:
Langdon, C. M., J. A. Freeman, and T. H. MacRae. 1991. Post translationally modified tubulins in Artemia: prelarval development in the absence of detyrosinated tubulin. Developmental Biology 148:147-155.

Freeman, J.A., L.B. Cheshire, and T.H. MacRae. 1992. Epithelial morphogenesis in Developing Artemia: The role of cell replication, cell shape change, and the cytoskeleton. Developmental Biology 152:279-292.

Okazaki, R.K., and J.A. Freeman. 1993. Cell growth and cuticle expansion in eyestalk-ablated grass shrimp, Palaemonetes puigio Holthuis. J. Crustacean Biology 13:125-133.

Freeman, J.A. 1993. The crustacean epidermis during larval development. Chapter 6 In: The Crustacean Integument: Morphology and Biochemistry. M.N. Horst and J.A. Freeman (Eds.). CRC Press, Boca Raton.

MacRae, T.H. and J.A. Freeman. 1995. Organization of the cytoskeleton in brine shrimp setal cells is molt-dependent. Can. J. Zoology 73: 765-774.

Freeman, J. A. 1995. Epidermal cell cycle and region-specific growth during segment development in Artemia. J. Exp. Zoology 271: 285-295.

Freeman, J. A. 1995. Relative growth of the tendinal cell and muscle in larval Artemia. Invert. Reprod. and Development, 28(3):205-210.

Freeman, J.A. and M. Porterfield. 1996. Nutrient stimulation of epidermal growth in developing Artemia. Aquaculture Nutrition, 2(4):201-206.