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.