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Department of Plant Biology
University of Minnesota
250 Biological Science Center
1445 Gortner Ave.
St. Paul, MN 55108

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Carolyn Silflow

Professor, Dept of Plant Biology
Ph.D., University of Georgia, 1977

Genetic mechanisms; Cytoskelton and cell motility; Plant cell and molecular biology

Contact Information

Mailing Address:

Dr. Carolyn Silflow
Department of Plant Biology
University of Minnesota
250 Biological Sciences Center
1445 Gortner Ave.
St. Paul, MN 55108

Research Techniques

• Cloning genes tagged by insertional mutagenesis in Chlamydomonas
• Genetic analysis of mutations in Chlamydomonas
• Immunofluorescence localization of proteins in cells
• Ultrastructural analysis of the basal body apparatus in Chlamydomonas cells
• Mapping molecular markers on the Chlamydomonas nuclear genome

Research Interests

Many aspects of cell growth and differentiation are dependent on the proper function of the cytoskeleton, a filamentious network found in all eukaryotic cells. We have focused on a molecular genetic analysis of the genes involved in the function of the microtubule component of the cytoskeleton in plant and algal cells. For example, we have studied the structure and expression of tubulin genes in the green alga Chlamydomonas and in the higher plants maize and Arabidopsis.

The current focus is on genes involved in replication, segregation, and localization of basal bodies in Chlamydomonas. Basal bodies are cylindrical organelles with walls composed of nine sets of triplet microtubules that serve as templates for assembly of doublet microtubules during the growth of cilia and flagella in eukaryotic cells. They are similar in structure to centrioles and these organelles are interchangeable in function in many cells. Although they were first described more than a century ago, little is currently known about the molecular basis of rotational asymmetry exhibited by these organelles or the molecular mechanisms necessary for their replication, segregation, or positioning in cells.

Chlamydomonas cells have two anterior flagella, which grow from basal bodies found beneath the plasma membrane. The basal body apparatus, consisting of basal bodies, microtubule rootlets and striated fibers that anchor and orient the basal bodies, serves as the microtubule organizing center in these cells. A similar apparatus is found associated with basal bodies in many types of ciliated/flagellated cells in animals and in primitive plants. We are studying mutations at seven different loci that result in phenotypes including variable flagellar number and positioning, and in defects in striated fibers. For four of these loci, we have cloned the wild-type gene, identified by its ability to complement the mutant phenotype when transformed into mutant cells.

We have cloned the genes identified by the vfll and vfl3 mutations reported earlier (Adams et al., 3. Cell Biol. 100:955 and Wright et al., 3. Cell Biol. 96:1697). The VFL1 gene encodes a novel protein of 132 kD which has leucine-rich repeat motifs near the N-terminus and a large predicted coiled-coil domain at the C-terminus. Results from immunofluorescence localization of an epitopetagged Vfll protein indicate that it localizes to both mature basal bodies and probasal bodies. Immunogold localization experiments showed that the protein localizes at the distal ends of mature basal bodies, inside the microtubule cylinder. Its association with triplets number 1, 2, and 9 suggests that the Vfll protein may be a molecular marker for basal body rotational asymmetry. The VFL3 gene encodes a protein of 65 ki) which has amino acid sequence homology with predicted protein encoded by ESTs from both human and mouse tissues.

A second project in collaboration with the Lefebvre laboratory is the construction of a molecular map of the Chlamydomonas genome. We have generated a map with more than 220 markers which is aligned with the genetic map of the seventeen linkage groups. The goal of the project is to create a physical map of BAC contigs which will facilitate the rapid cloining of genesidentified by mutation.

Selected Publications

Chen, Q., and C.D. Silflow (1996) Isolation and characterization of glutamine synthetase genes in Chlamydomonas reinhardtii. Plant Physiol. 112:987-996.

Lechtreck, K.-F. And C.D. Silflow (1997) SF-assemblin in Chlamydomonas: Sequence conservation and localization during the cell cycle. Cell Motil. Cytoskel. 36:190-201.

Silflow, C.D. (1998) Organization of the nuclear genome. IN: The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas. (J.-D. Rochaix, M. Goldschmidt-Clermont, and S. Merchant, eds.). Kluwer Academic Publishers, The Netherlands. Pp. 25-40.

Lefebvre, P.A. and C.D. Silflow (1999) Chlamydomonas: The cell and its genomes. Genetics 151:9-14.

Silflow, C.D., B. Liu, M. LaVoie, E.A. Richardson, and B.A. Palevitz (1999) Gamma-tubulin in Chlamydomonas: Characterization of the gene and localization of the gene product in cells. Cell Motil. Cytoskel. 42:285-297.

Silflow, C.D., M. LaVoie, L.-W. Tam, S. Tousey, M. Sanders, W.-C. Wu, M. Borodovsky, and P.A. Lefebvre (2001) The Vf11 protein in Chlamydomonas localizes in a rotationally asymmetric pattern at the distal ends of the basal bodies. J. Cell Biol. 153:63-74.

Brazelton, W.J., C.D. Silflow, and P.A. Lefebvre (2001) The bld1 mutation identifies the Chlamydomonas osm-6 homolog as a gene required for flagellar assembly. Current Biol. 11:1591-1594. Download [PDF, 316 KB]

Kathir, P., M. LaVoie, W.J. Brazelton, N.A. Haas, P.A. Lefebvre, and C.D. Silflow (2003) Molecular map of the Chlamydomonas reinhardtii nuclear genome. Eukaryotic Cell 2:362-379.