Research in my laboratory concerns mechanisms that control early development. We are examining how sperm initiate the development of the egg, mechanisms that control meiotic cell division and those that control egg and embryo organization and differentiation. Much of this research has centered on embryos of the marine annelid, Chaetopterus.

Using the techniques of aequorin imaging we have demonstrated that Chaetopterus eggs undergo repetitive waves of intracellular calcium ion release upon fertilization or activation by excess extracellular potassium ions. This was the first demonstration of calcium waves in a fertilized protostome egg and therefore provided important support to the theory that calcium ion fluxes are a major universal factor in the initiation of development. We re currently extending these studies by examining the biochemical mechanisms for calcium sequestration and release in these eggs. To test the hypothesis that increased intracellular pH is also a major factor in the initiation of development, we used fluorescent imaging techniques to examine the intracellular pH of Chaetopterus eggs during oocyte maturation and after activation. The results showed that the pH did not change during either of these time periods, demonstrating that changes in intracellular pH are not a significant signal in the early development of this organism. We are currently extending these studies by examining the signal transduction mechanisms in the eggs. Two aspects of signal transduction are currently under study. We are identifying G-proteins in the eggs and examining their possible roles in fertilization and oocyte maturation; we are also identifying protein tyrosine phosphatases in Chaetopterus and mouse eggs to try to determine what roles these important cellular regulators play.

We have published a number of studies showing that treatment of these oocytes with tumor-promoting phorbol esters elicits activation of M-phase promoting factor. We are currently investigating the mechanisms by which this activation occurs. Recent evidence appears to rule out MAP kinase as an intermediate.

Other studies in our lab investigated the mechanisms that control the organization of the cytoskeleton in the egg and in later differentiation.

RECENT PUBLICATIONS:

Byrnes, W.M. and W.R. Eckberg. 2006. Ernest Everett Just (1883-1941) – An early ecological developmental biologist. Dev. Biol. 296, 1-11.

Yang, D., Hinton, S.D. and W.R. Eckberg. 2004. Regulation of cleavage by protein kinase C. Mol. Reprod. Dev. 69, 308-315.

Hinton, S.D., D. Yang and W.R. Eckberg. 2003. A role for protein tyrosine phosphatase in Chaetopterus pergamentaceus oocyte activation. Dev. Growth Differ. Dev. Growth Differ.45, 405-415.

Howell, K.P., A. Skipwith, A. Galione and W.R. Eckberg. 2003. Phospholipase C-dependent calcium release by Chaetopterus egg homogenates in response to mammalian sperm factor. Biochem. Biophys. Res. Commun. 307,47-51.

Wanga, J., W.R. Eckberg and W.A. Anderson. 2001. Ultrastructural differentiation of cardiomyocytes of the zebrafish during the 8-26-somite stages. J. Submicroscop. Cytol. Pathol. 33,275-287.

Balan, K.V., V.W. Hollis, W.R. Eckberg, F. Ayorinde, J.D. Karkera, J.H. Wyche and W.A. Anderson. 2001. Cathepsin B and complement C3 are major comigrants in the estrogen-induced peroxidase fraction of rat uterine fluid. J. Submicroscop. Cytol. Pathol. 33,221-230.

Thomas, T.W., W.R. Eckberg, F. Dubé and A. Galione. 1998. Mechanisms of calcium release and sequestration in eggs of Chaetopterus pergamentaceus. Cell Calcium 24, 285-292.

Eckberg, W.R. 1997. MAP and cdc2 kinase activities at gerninal vesicle breakdown in Chaetopterus. Dev. Biol. 191, 182-190.

Dubé, F. and W.R. Eckberg. 1997. Intracellular pH increase driven by an Na+/H+ exchanger upon activation of surf clam oocytes. Dev. Biol.190, 41-54

Eckberg, W.R. and W.A. Anderson 1997. The initiation of development in Chaetopterus. In Progress in Developmental Biology (Ed. J. R. Collier), pp. 109-135, Vol. VIII in Reproductive Biology of Invertebrates (Eds. K.G. Adiyodi and R.G. Adiyodi), Wiley.

Eckberg, W.R., M.R. Johnson and R.E. Palazzo. 1996. Regulation of maturation-promoting factor by protein kinase C in Chaetopterus oocytes. Invert. Reprod. Dev. 30, 71-79.

Eckberg, W.R. and F. Dubé. 1996. Effects of altering pHi and pHo on the activation of Chaetopterus eggs. Biol. Bull. 191, 280-281.

Dubé, F. and W.R. Eckberg. 1996. Intracellular pH measurements during fertilization of surf clam (Spisula solidissima) oocytes. Biol. Bull. 191, 279-280.

Eckberg, W.R. and S.D. Hill. 1996. Chaetopterus - oocyte maturation, early development and regeneration. Biol. Bull. Mar. Models Electronic Rec. Available from http://www.mbl.edu/html/BB/MMER/ECK/EckTit.html.

Eckberg, W.R. and W.A. Anderson. 1995. Cytoskeleton, cellular signals, and cytoplasmic localization in Chaetopterus embryos. In Role of the Cytoskeleton in Early Development (Ed. D.G. Capco). Vol. 31 In Current Topics in Developmental Biology. pp 5-39.

Eckberg, W.R. and A.L. Miller. 1995. Propagated and nonpropagated calcium transients during egg activation in the annelid, Chaetopterus. Dev. Biol. 172, 654-664.

Zhang, S.-H., W.R. Eckberg, Q. Yang, A.A. Samatar and N.K. Tonks. 1995. Biochemical characterization of a human band 4.1-related protein tyrosine phosphatase, PTPH1. J. Biol. Chem. 270, 20067-20072.

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