Igor B. Dawid,
Ph.D., Principal Investigator
Reiko Toyama, Ph.D., Staff
Scientist
Mizuki Azuma, Ph.D., Postdoctoral
Fellow
Neil Hukriede, Ph.D., Postdoctoral
Fellow
Atsuo Kawahara, Ph.D., Postdoctoral
Fellow
Tetsuhiro Kudoh, Ph.D., Postdoctoral
Fellow
Tatjana Piotrowski, Ph.D., Postdoctoral
Fellow
Nobuhiro Takahashi, Ph.D., Postdoctoral
Fellow
Michael Tsang, Ph.D., Postdoctoral
Fellow
Gert Veenstra, Ph.D., Postdoctoral
Fellow
Raymond Habas, Predoctoral
Fellow
Martha Rebbert, Senior
Technician
Elizabeth Laver, Technician
Diego Gomez, Student
For More Information
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The laboratory has studied the molecular basis of embryogenesis in Xenopus
laevis and the zebrafish, with special emphasis on axis determination
and pattern formation. We have investigated the regulation of these events
by cell-to-cell signaling and by the spatially and temporally regulated
action of transcription factors in several related systems.
The Role of Xlim-1 in Gastrulation
Hukriede, Dawid in collaboration with D. Weeks,University of Iowa
The Xlim-1 gene encodes a LIM-homeodomain protein that is
involved in the functions of the Spemann organizer in neural induction
and mesoderm patterning; it also plays a role in kidney formation. While
a mouse knockout has been reported and shown to lack anterior head, we
believe that the Xenopus gastrula allows a more detailed study
of Xlim-1's function. Therefore, we study Xlim-1 function
through an oligonucleotide antisense strategy, using DEED (diethylethylenediamine)
antisense oligonucleotides that are stable in the embryo and that have
been successfully used before (see Veenstra et al.). We find that
the antisense oligos greatly reduce Xlim-1 mRNA concentration and
lead to gastrulation defects and consequently failure of head formation.
Somewhat surprisingly, most organizer-specific genes are activated normally
in Xlim1-depleted embryos, but gastrulation movements, critical for germ
layer establishment, are impaired. Thus, we conclude that regulation of
cell movements is a major function of the Xlim-1 gene in the early
embryo.
A Gene Expression Screen in the Zebrafish
Kudoh, Tsang, Hukriede, Dedekian, Clarke, Kiang, Schultz, Toyama, Dawid
in collaboration with X. Chen and J. Epstein, UBC, NICHD
With the aid of high-throughput in situ hybridization, we have screened
for developmentally regulated genes in zebrafish by searching for genes
with restricted expression patterns. Such screens have been carried out
in other developmental systems and have revealed interesting information.
We have screened about 2,700 randomly picked cDNA clones from a normalized
library and selected about 350 genes for further analysis. By partial
sequencing, we could classify many of the genes into functional groups,
showing that the selected set contained a preponderance of regulatory
genes that encode either transcription factors or components of signal
transduction pathways. We put the resulting information to three different
uses. First, we identified particularly interesting genes for further
study, including the iro3 gene. Second, we took advantage of mapping
information about many of the clones that we generated with radiation
hybrid mapping (see Hukriede et al.). With a map position and expression
pattern known, a cDNA clone becomes an excellent candidate gene for the
many developmental mutations that exist in the zebrafish. In at least
one case, we matched one of the cDNAs to a mutation (studied by others)
that affects ear development; the gene is still under study. Third, we
used cDNAs from the screen to generate a detailed molecular anatomy atlas
of the embryo, in which functional domains are characterized by gene expression
rather than by morphology alone.
The Role of the iro3 Gene during Gastrulation
Kudoh, Dawid
Iroquios genes represent a subgroup of homeobox genes that are
known to have a role in neural development. In our studies, we observed
that the iro3 gene is already expressed during the blastula and
gastrula stages in the zebrafish embryo in a dorsal endodermal domain
(Figure 1).
In overexpression and inhibition studies, we showed that the early expression
of iro3 plays a role during gastrulation in the specification of
the dorsal axis and the activation of other organizer-specific genes.
It appears that iro3 acts in a distinct manner during the early
stages, along with its later role in neural plate differentiation. Repeated
use of the same gene during subsequent stages of development is a known
feature of many regulatory genes.
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PUBLICATIONS
- Andreazzoli
M, Broccoli V, Dawid IB. Cloning and expression of noz1, a zebrafish
zinc finger gene related to Drosophila nocA. Mech Dev 2001;104,117-120.
- Cai
T, Krause MW, Odenwald WF, Toyama R, Notkins AL. The IA-2 gene family:
homologs in Caenorhabditis elegans, Drosophila and zebrafish. Diabetologia.
2001;44:81-88.
- Chin
AJ, Tsang M, Weinberg ES. Heart and gut chiralities are controlled
independently from initial heart position in the developing zebrafish.
Dev Biol 2000;227:403-421.
- Dawid
IB, Chitnis AB. Lim homeobox genes and the CNS: a close relationship.
Neuron 2001;30:301-303.
- Hayes
WP, Yangco N, Chin H, Mill JF, Pu LP, Taira M, Dawid IB, Gallo V.
Expression and regulation of the LIM-class homeobox gene rlim-1
in neuronal progenitors of the rat cerebellum. J Neurosci Res 2001;63:237-251.
- Hibi M, Hirano T, Dawid IB. Organizer formation and function. In:
Solnica-Krezel L, ed. Pattern formation in zebrafish. New York: Springer-Verlag,
2001, in press.
- Hukriede
NA, Fisher D, Epstein JA, Joly L, Tellis P, Zhou X, Barbazuk B, Cox
K, Fenton-Noriega L, Hersey C, Miles J, Sheng X, Song A, Waterman R,
Johnson SL, Dawid IB, Chevrette M, Zon LI, McPherson J, Ekker M.
The LN54 radiation hybrid map of zebrafish expressed sequences. Genome
Res 2001, in press.
- Hukriede NA, Weinstein B, Dawid IB. Embryological, genetic and molecular
tools for investigating embryonic kidney development. In: Vize P, Adrian
Woolf A, Jonathan Bard J, eds. The kidney: from normal development to
congenital abnormalities. New York: Academic Press 2001, in press.
- Kawahara
A, Dawid IB. Critical role of biklf in erythroid cell differentiation
in zebrafish. Current Biol 2001;11:1353-1357.
- Kodjabachian
L, Karavanov AA, Hikasa H, Hukriede NA, Aoki T, Taira M, Dawid IB.
A study of Xlim1 function in the Spemann-Mangold organizer. Int J Dev
Biol 2001;45:209-218.
- Kudoh
T, Dawid IB. Role of the iroquois3 homeobox gene in organizer
formation. Proc Natl Acad Sci USA 2001;98:7852-7857.
- Kudoh
T. Dawid IB. Zebrafish mab21l2 is specifically expressed
in the presumptive eye and tectum from early somitogenesis onwards.
Mech. Dev 2001;109:95-98.
- Kudoh
T, Tsang M, Hukriede NA, Chen X, Dedekian M, Clarke CJ, Kiang A, Schultz
S, Epstein JA, Toyama R, Dawid IB. A gene expression screen in zebrafish
embryogenesis. Genome Res 2001;11:1979-1987.
- Veenstra
GJ, Weeks DL, Wolffe AP. Distinct roles for TBP and TBP-like factor
in early embryonic gene transcription in Xenopus. Science. 2000;290:2312-2315.
- Veenstra
GJ, Wolffe AP. Gene selective developmental role of general transcription
factors. Trends Biochem Sci 2001;26:665-671.
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