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RESEARCH INTERESTS
Developmental neurobiology
growth-cone motility
time-lapse imaging
lipocalin function
PUBLICATIONS
My lab is studying the problem of growth cone guidance
during the development of the nervous system. There are
two main projects in my lab, one studying the dynamic
behavior of growth cones in the nematode C. elegans
and the other studying the function of a new family of
proteins, lipocalins, that regulate specific growth cone
behaviors.
In the first project the simple, well-characterized nervous
system of the nematode C. elegans provides us with
an opportunity to study the behavior of growth cones
in vivo. Distinct cellular landmarks are known and
can be easily visualized in the transparent worm.
C. elegans is a powerful genetic system ; as a result
many molecules required for axonal outgrowth have been
identified. The ultimate goal of our research is to observe the
behavior of growth cones in vivo and correlate
changes in behavior with specific molecular mutations. Our
preliminary results show that time-lapse laser-scanning
confocal microscopy can be used to visualize growth cones
as they migrate in vivo. We have found that distinct
behavioral changes are exhibited by growth cones as they
interact with different cellular substrates. These changes
and the nature of these modifications to growth cone
behavior can be analyzed using a variety of approaches. As
a result we have developed an assay for observing the
behavior of growth cones as they migrate in the complex
molecular environment of the living animal. Now the
function of any molecule regulating growth cone behavior
can be determined by disrupting the function of that
molecule genetically and observing the resultant behavioral
changes that growth cones exhibit in the mutant environment.
In the second project we are studying the function of
lipocalins in nervous system development. The lipocalins
are a large family of small globular proteins that have
diverse functions as ligands of hydrophobic molecules. We
have discovered a group of homologous lipocalins that are
expressed in the developing nervous system of the
grasshopper, fruitfly, mouse, and human. A member of this
group, Lazarillo (Laz), was discovered via a mAb screen for
antigens expressed on subsets of developing neurons. We
showed that Laz is involved in the axonal guidance of an
identified pair of grasshopper neurons. The Laz DNA
sequence was used to identify homologs in the fruitfly,
mouse, and human genome. A phylogenetic analysis
supports the identification of Drosophila Droslip
(Dlip) and Newlip (Nlip) as genes homologous to the
grasshopper Laz. It also supports the homology of these
insect lipocalins to the vertebrate ApoD gene. Together,
these proteins form an ancestral group of lipocalins within
the metazoan lineage. We have shown that these lipocalins
all share expression in subsets of cells in the developing
nervous system of grasshopper, fly, and mouse. ApoD
accumulates under the following conditions: 1) during
regeneration of rat, rabbit, and monkey peripheral nerves,
2) in hippocampal neurons undergoing cell death induced by
experimental treatment with kainic acid, and 3) in the
hippocampus and cerebrospinal fluid of patients with
Alzheimer's disease. ApoD has been related also to the
inhibition of cell growth in several cancers and cell culture
studies.
Our results show that Laz, the two novel Drosophila
lipocalins, and ApoD are homologous members of a well-
defined subfamily of functionally related lipocalins. The
goal of my lab is to characterize the function of these
lipocalins in the development of the nervous system. We
will assay the consequences of eliminating or altering the
expression or function of these lipocalins in the grasshopper,
fruitfly, and mouse embryo. We will exploit the unique
advantages of each of the organisms; the grasshopper offers
a large highly accessible embryo ideal for dynamic cellular
studies at all stages in the developmental life of a neuron,
Drosophila offers powerful genetic techniques and
many well-defined markers of nervous system development,
and the mouse will specifically address the function of ApoD
in the development of the human nervous system, and its
role in the pathophysiology of several human neural diseases.
Selected Publications
Sãnchez, D., M.D. Ganfornina, G. Gutierrez and M.J. Bastiani.
1998. Molecular characterization and phylogenetic
relationships of a protein with oxygen-binding capabilities
in the grasshopper embryo. A hemocyanin in insects?
Molecular Biology and Evolution 15: 415-426.
Ganfornina, M.D. and M.J. Bastiani. 1998. Growth cones.
In: Encyclopedia of Neuroscience (2nd Edition). Ed.: G.
Adelman. Birkhäuser, Boston.
Ganfornina, M.D., D. Sãnchez and M.J. Bastiani. 1999.
Developmental expression and molecular characterization
of two gap junction channel proteins expressed during
embryogenesis in the grasshopper Schistocerca
americana. Developmental Genetics 24:
137-150.
Hayward, D.C., M.J. Bastiani, J.W. Trueman, L.M. Riddiford and
E.E. Ball. 1999. The sequence of Locusta RXR,
homologous to Drosophila Ultraspiracle, and its
evolutionary implications. Dev. Genes Evol.
209(9) :564-71.
Knobel, K., E.M. Jorgensen and M.J. Bastiani. 1999. Growth
cones stall and collapse during axon outgrowth in
C. elegans. Development 126: 4489-4498.
Ganfornina, M., G. Gutierrez, M. Bastiani and D. Sãnchez. 2000.
A phylogenetic analysis of the lipocalin family. Mol. Biol.
Evol. 17(1) :114-26.
Sãnchez, D., M.D. Ganfornina, S. Torres-Schumann, S.D.
Speese, J.M. Lora and M.J. Bastiani. 2000. Characterization
of two novel lipocalins expressed in the Drosophila
embryonic nervous system. Int. J. Dev. Biol. 44(4)
:349-59.
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