Our
research focus:
Research in the Morris Lab is centered on understanding the roles of cell movement
in animal development. Cells are complex and dynamic machines
which can generate force along their own skeletons to move and to
divide. My students and I are investigating how movement is generated
within cells, and how these movements are involved in cell growth and
differentiation.
In particular, we study the roles of
kinesins, a superfamily of microtubule-based motor proteins, in sea
urchin development. We study these
processes in sea urchin embryos
because these embryos are easy to create, easy to culture, beautiful to
look at, amenable to experimentation, similar to human cells in
fundamental ways, and because studying sea creatures takes us to the
coast. We employ basic techniques for studying cell development
including genomics, light and fluorescence microscopy, microinjection,
digital
imaging, and digital image analysis.
We welcome comments and suggestions on our
projects and webpages. - Dr. Bob
Some of our recent work:
Analysis of Cytoskeletal and Motility
Proteins in the
Sea Urchin Genome Assembly
R.L. Morris 1, M.P.
Hoffman 2, R.A. Obar 3, S.S. McCafferty 1, I.R.
Gibbons 4, A.D. Leone 2, J. Cool 1, E.L. Allgood 1, A.M. Musante 1, K.M. Judkins 1,
B.J. Rossetti 1, A.P. Rawson 1, D.R. Burgess 2.
Developmental
Biology (in press).
1Department of Biology, Wheaton College, Norton, Massachusetts 02766
2Department of Biology, Boston College, Chestnut Hill, MA 0246
3Tethys Research, LLC, 53 Downing Road, Bangor, Maine 04401; Present
Address: Massachusetts General Hospital Cancer Center, Charlestown, MA
02129.
4Department of Molecular and Cell Biology, University of California,
Berkeley, CA 94720
Link to R.L. Morris et al, 2006 through
PubMed (coming shortly)
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Abstract
The sea urchin embryo is a classical model system for
studying the role of the cytoskeleton in such events as fertilization,
mitosis, cleavage, cell migration and gastrulation. We have
conducted an analysis of gene models derived from the
Strongylocentrotus purpuratus genome assembly and have gathered strong
evidence for the existence of multiple gene families encoding
cytoskeletal proteins and their regulators in sea urchin. While
many cytoskeletal genes have been cloned from sea urchin with sequences
already existing in public databases, genome analysis reveals a
significantly higher degree of diversity within certain gene
families. Furthermore, genes are described corresponding to
homologs of cytoskeletal proteins not previously documented in sea
urchins. To illustrate the varying degree of sequence diversity
that exists within cytoskeletal gene families, we conducted an analysis
of genes encoding actins, specific actin-binding proteins, myosins,
tubulins, kinesins, dyneins, specific microtubule-associated proteins,
and intermediate filaments. We conducted ontological analysis of
select genes to better understand the relatedness of urchin
cytoskeletal genes to those of other deuterostomes. We analyzed
developmental expression (EST) data to confirm the existence of select
gene models and to understand their differential expression during
various stages of early development.
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Redistribution of the
kinesin-II subunit KAP from
cilia to nuclei during the mitotic and ciliogenic cycles in sea urchin
embryos
R.L. Morris 1, C.N.
English 1, J.E. Lou 1, F.J. Dufort 1, J.J. Nordberg 1, M.
Terasaki 2, B. Hinkle 2.
Developmental
Biology
274:56-69. 2004.
1Wheaton College, Norton,
MA; 2University of Connecticut Health Center,
Farmington CT
Abstract
KAP is the non-motor subunit of the heteromeric
plus-end directed microtubule (MT) motor protein kinesin-II essential
for normal cilia formation. Studies in Chlamydomonas have
demonstrated that kinesin-II drives the anterograde intraflagellar
transport (IFT) of protein complexes along ciliary axonemes. We
used a green fluorescent protein (GFP) chimera of KAP, KAP-GFP, to
monitor movements of this kinesin-II subunit in cells of sea urchin
blastulae where cilia are retracted and rebuilt with each
mitosis. As expected if involved in IFT, KAP-GFP localized to
apical cytoplasm, basal bodies, and cilia, and became concentrated on
basal bodies of newly forming cilia. Surprisingly, after ciliary
retraction early in mitosis, KAP-GFP moved into nuclei before nuclear
envelope breakdown, was again present in nuclei after nuclear envelope
reformation, and only decreased in nuclei as ciliogenesis
reinitiated. Nuclear transport of KAP-GFP could be due to a
putative nuclear localization signal and nuclear export signals
identified in the sea urchin KAP primary sequence. Our
observation of a protein involved in IFT being imported into the
nucleus after ciliary retraction and again after nuclear envelope
reformation suggests KAP115 may serve as a signal to the nucleus to
reinitiate cilia formation during sea urchin development.
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Honors Thesis presented by
Jonah Cool
Wheaton College, May 22, 2004
Identification of
Candidate Regulatory Sequences for Ciliary Genes
Abstract
A gene battery is a collection of related genes that are expressed in
unison. When a gene battery is responsible for regulating a group of
genes, the genes share spatial and temporal expression patterns.
Empirical evidence suggests that cilia are candidates for coordinate
regulation and could be subject to control by a gene battery based upon
temporal expression of necessary proteins. A gene battery regulates
sets of genes through consensus sequences upstream of every gene
included. We hypothesize that consensus sequences have been
evolutionarily conserved upstream of genes coding for unique ciliary
proteins and are responsible for the regulation of ciliary gene
battery. To test this hypothesis, we performed comparative sequence
analysis, in Chlamydomonas, upstream of twelve candidate ciliary genes
from the dynein heavy chain and radial spoke protein families. Sequence
analysis revealed five different motifs upstream of all twelve
candidate ciliary genes. Of the five motifs, three stood out as
putative binding elements. Based upon this data, we can conclude that
consensus sequences exist upstream of ciliary genes and could
coordinate regulation of a gene battery comprised of unique ciliary
genes.
Figure 1.2a. A
possible ciliary gene battery.
The red arrow, in the top left, shows a transcription factor produced
during the cell cycle. Transcription of the gene regulated by “Cell
Cycle Control” produces the ciliogenesis launcher transcription
protein. The ciliogenesis launcher transcription protein is a binding
factor (shown as a red arrow) that regulates twelve ciliary genes. This
figure visualizes the ability of a single factor to coordinately
regulate alarge sub-set of ciliary genes. Each downward red arrow
indicates a protein factor being able to influence regulation of the
gene to whose upstream region it is directed. (figure based on Erwin
and Davidson, 2002, Development 129:3021-32.)
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