Research Interests

     Our lab is interested in growth control and morphogenesis in zebrafish development. Thus, we
     study the pigment pattern and the control of size and regeneration of the fin. Our basic approach is
     to identify mutations that affect adult pigment stripe pattern or fin growth and regeneration and
     analyze the mutations in singly or multiply mutant fish to identify the tissues and genetic pathways
     affected. Additionally, we are trying to identify the genes affected by the mutations, and are working
     to develop genetic and physical maps that will lead to isolation of these genes.

     Melanocyte stem cells. Between 2 and 4 weeks of development the embryonic pigment pattern is
     replaced by the adult pigment pattern. Analysis of mutations indicates that the melanocytes of the
     adult pigment pattern develop from multiple populations of undifferentiated precursors or stem
     cells that are presumably derived from the embryonic neural crest. Adult melanocyte stem cells
     are activated to develop at distinct stages of development, as the animal grows, or in regenerating
     fins following amputation. We are now working to identify the different populations of stem cell
     in the adult tissue.

     Proportionate growth. Zebrafish grow throughout their lives, slowing the rate of growth after
     reaching maturity. The rates of growth of the fins and the body are regulated to achieve constant
     proportion of fin length to body length at all stages. From phenotypes of mutations that affect fin
     size, we infer that the long fin mutation relieves the coupling between fin growth and body
     growth, and the short fin mutation retains coupled growth, but changes the proportionality
     constant. Identifying the affected genes by positional cloning or candidate gene approaches will
     shed light on the mechanisms that impose proportionate growth on the different tissues and organs
     of vertebrate animals.

     Zebrafish fins regenerate rapidly following amputation. Fin regeneration is similar to amphibian
     limb regeneration; following amputation, differentiated bone cells apparently dedifferentiate and
     enter the cell cycle, rapidly divide and migrate from the stump to form a regeneration blastema.
     Formation of the blastema is followed by a period of rapid growth, with continued proliferation of
     some blastema cells matched by withdrawal of other cells from both the blastema and the cell cycle
     to form new bone. Analysis of mutations should help to understand the molecular basis of these
     growth control mechanisms.

  Keywords:
     zebrafish genetics, growth control , development, regeneration, melanocytes



This page last updated on October 22, 2001.