Thirty-six out of the one hundred and thirty nine posters presented
at this year's meeting were submitted and eligible for the Best Poster
Competition. A panel of seven judges, consisting of four women and three
men, representing most areas of developmental biology, viewed the posters,
interviewed each author and met several times to discuss and select the
winners. Posters were evaluated for their overall quality of presentation,
content, scientific impact and author interview. The final decisions of
the judges represent unanimous choices for each category.
Partial financial support for the Poster Competition was provided
by PharMingen, San Diego, CA.
First Place
Steven Wang, Fred J. Griffin and Wallis H. Clark, Jr.. Center for
Structural Biology, University of Florida, Gainesville, FL. "Induction of
the Cephalic Segments by the Mesendoderm Cells in the Embryo of the Marine
Shrimp Sicyonia ingentis."
In this classical study, Steven utilized blastomere isolation and
recombination to characterize the role of the mesendoderm cells in the
induction of the three head segments which form in this early embryo. With
this as a foundation, he then proceeded to explore this induction. Adding
mesendoderm cells to non-mesendoderm blastulae resulted in the rescue of
segmentation through cell contact alone and in a planar fashion, as grafted
blastomeres did not migrate within or become incorporated into their host.
Moreover, a window of inductive competence was shown to exist for the
non-mesendoderm blastulae and that the mesendoderm cells retained their
ability to induce segmentation beyond the host's ability to respond. The
judges unanimously felt that this work was professionally presented, a joy
to view and logically written. In addition, this work has created a
foundation from which many experiments may now be done to further clarify
the inductive signals and events in this system.
The First Place winner receives a one-year subscription to
Developmental Biology and the airfare for the trip to England to present
his work at the British Society for Developmental Biology Annual Meeting.
The British SDB will host Steven as part of the exchange program between
our societies.
Second Place
Martin F. Offield, Jetton, T.L., Labosky, P., Ray, M., Stein, R., Magnuson,
M., Hogan, B.L.M., and Wright, C.V.E. Department of Cell Biology,
Vanderbilt University, School of Medicine, Nashville, TN. "PDX-1 is
Required for the Development and Differentiation of the Pancreas and
Rosteral Duodenum."
In this striking poster the powerful role of homeobox genes in
development is demonstrated. Here the homologue for XlHbox 8, pdx-1, was
investigated using gene targeting to generate two independent null
mutations in the mouse. Examination of homozygous null mutants revealed a
complete absence of the pancreas in addition to malformations of the
rostral duodenum. This result was supported by a lack of immunostaining
for markers of pancreatic cells and modifications or absence of normal gut
epithelial lining, villi and Brunner's glands. A second null allele
utilizing a lacZ reporter was phenotypically identical to the first null
mutant and revealed that pdx-1/bgal expression is first seen in both +/-
and -/- mutants at the 8.0 dpc in the left ventral endoderm at the anterior
intestinal portal. This result suggests that pdx-1 functions in
reorganization of the posterior foregut and directs the differentiation of
both pancreatic and duodenal derivatives in this region. The judges were
most impressed by the author's breadth of knowledge in addition to his
extensive contribution to this body of work. The Second Place winner receives a one-year subscription to Developmental Biology and a cash prize of one hundred dollars.
Third Place
Gabrielle Kardon, Zoology, Duke University. "A Role for Tendons in
Specifying Muscle Pattern?"
This represents a continuation of the work Gabrielle presented just
eight months earlier, at the annual SDB meeting in San Diego, where her
stunning work received an honorable mention. Previously, Gabrielle showed
utilizing whole mount immunofluorescence that muscle and tendon
morphogenesis occur in contact and in tandem during normal development.
Her current work now demonstrates that the tendons of muscleless limbs when
grafted into the coelomic cavity undergo normal temporal and spatial
patterning in the absence of muscle. Her results suggest that the
autonomous development of tendon may specify muscle pattern and she has
some intriguing ideas about how tendon pattern may be established in these
limbs. Gabrielle receives a one-year subscription to Developmental Biology and a copy of the video "A dozen eggs" by Rachel Fink.
Honorable Mention
Vida Praitis, Caroline McKeown, Alpa Patel and Judith Austin. Department
of Molecular Genetics and Cell Biology. University of Chicago, IL. "sma-1
is Required for Morphogenesis of the C. elegans embryo."
In this study, the role of cortical actin microfilament
reorganization during embryo elongation was investigated. Abnormal
elongation in the sma-1 mutant was shown to correlate with abnormal
microfilament organization and was rescued by injection of an 11 kb genomic
fragment. Characterization of the fragment suggests similarities to
Drosophila ßH-Spectrin. Currently, the expression of this gene in larvae
and adults via Northern blot and in situ analysis is being characterized.
Vida received a copy of Klaus Kalthoff's latest edition of Analysis of
Biological Development.
David M. Parichy, Section of Evolution and Ecology, University of
California at Davis. "Metamorphosis of the Pigment Pattern in the
Salamander Ambystoma tigrinum tigrinum"
This work continues investigations which revealed a relationship
between neural crest derived pigment cells and the developing lateral line
sensory system. Previously, David had shown that ablation of cranial
lateral line placodes resulted in the loss of horizontal pigment stripes on
the flanks of larvae. In this study, he followed these animals through
metamorphosis and adult pigmentation. His results revealed that
post-metamorphic patterns of pigmentation were not affected by ablation of
the lateral line suggesting that metamorphosis decouples larval and adult
pigment patterns. The judges were impressed by the clear and memorable
message of this poster. David received a copy of Scott Gilbert's latest
edition of Developmental Biology.
Tammy F. Wu, Stephen C. Ekker, Philip A. Beachy and Marnie E. Halpern.
Department of Molecular Biology and Genetics, Johns Hopkins University
Medical School, Baltimore, MD. "Segregation of Hedgehog Gene Expression
During Zebrafish Gastrulation"
In this study, Tammy investigated the temporal and spatial
expression of two hedgehog related genes, sonic and tiggy winkle, in
addition to the gene no tail, via in situ hybridization. Her results
revealed that while all three genes are expressed in single cells of the
dorsal shield in early gastrulae, in older gastrulae tiggy winkle and sonic
hedgehog become segregated into distinct cell layers. Sonic becomes
localized along with no tail expression into axial mesoderm which gives
rise to notochord, while tiggy winkle transcripts are found exclusively in
overlying cells. It is hyothesized that these cells may define a
population of cells that are precursors to the future floor plate.
Interestingly, segregation of gene expression for tiggy winkle and sonic
was disrupted in no tail mutants which fail to form notochord. Besides her
beautiful in situ hybridization work, the judges were impressed by her
organization, humor and thoughtful questions. For example: What is a germ
layer? Tammy received a copy of Klaus Kalthoff's latest edition of
Analysis of Biological Development.
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