Magdalena Bezanilla

Assistant Professor of Biology, University of Massachusetts

Email: bezanilla@bio.umass.edu
M. Bezanilla Biology Web Site

Ph.D.: Johns Hopkins School of Medicine
Postdoctoral Training: Washington University at St. Louis

Research Interests

My lab studies the molecular mechanisms behind plant cell growth. In particular we are focusing on the mechanisms leading to the very polar and directed form of growth known as tip growth. Tip growth is a fundamental form of growth throughout all known plant taxa. The actin cytoskeleton provides the driving force for tip growth in many cell types. However, the regulation of the dynamics of the actin cytoskeleton in plant cells is an open question. We are investigating how actin-binding proteins affect dynamics in the cell and how they regulate tip growth.

We are studying these questions in two evolutionarily divergent plant model systems: a moss, Physcomitrella patens , and an angiosperm, Arabidopsis thaliana. Physcomitrella is an excellent organism for studying tip growth because the major colonizing growth tissue grows via tip growth and its developmental pattern is quite simple compared to other land plants. Physcomitrella is also the only known land plant that undergoes efficient homologous recombination which opens the possibility for gene replacement studies as well as targeted knockouts. In addition my lab has developed a fast and reliable transient RNA interference method allowing the possibility of analyzing loss-of-function phenotypes for genes belonging to large gene families. By studying mutant phenotypes in moss, the relatively simply model, we can dissect the molecular basis of the observed phenotypes at the cellular level. This will direct our studies in Arabidopsis where development is relatively more complicated and cellular defects are not as easily identifiable.

Current projects include understanding the cellular regulation of ADF, an important actin binding protein, required for controlling actin dynamics. My work in Physcomitrella has shown that ADF is essential for tip growth. Using molecular tools including complementation of null and knockdown phenotypes, we will investigate how ADF is regulated in vivo and which form of regulation is relevant for tip growth. We will study interactions between ADF and other proteins to begin to understand how ADF-mediated actin dynamics is regulated in plant cells.

Representative publications:

Bezanilla, M. , Perroud, P-F, Pan, A., Klueh, P., and Quatrano, R.S. 2005. An RNAi System in Physcomitrella patens with an Internal Marker for Silencing Allows for Rapid Identification of Loss of Function Phenotypes. Plant Biology, 7 : 251-257.

Bezanilla, M. , Pan, A., and Quatrano, R.S. 2003. RNAi in the moss Physcomitrella patens. Plant Physiology, 133 : 470-474.

Bezanilla, M. , Horton, A.C., Sevener H.M., and Quatrano, R.S. 2003. Phylogenetic Analysis of New Plant Myosin Sequences. Journal of Molecular Evolution, 57 : 229-239.

Lee, W.L., Bezanilla, M. , and Pollard, T.D. 2000. Fission Yeast Myosin-I, Myo1p, Stimulates Actin Assembly by Arp2/3 Complex and Shares Functions with WASp. Journal of Cell Biology, 151 (4): 789-799.

Bezanilla, M. , Wilson, J., and Pollard, T.D. 2000. Myosin-II Isoforms in Fission Yeast Assemble into the Contractile Rings at Distinct Times During Mitosis. Current Biology , 10 (7): 397-400.

Bezanilla, M. , and Pollard, T.D. 2000. Myosin-II Tails Confer Unique Functions in S. pombe : Characterization of a Novel Myosin-II Tail. Molecular Biology of the Cell , 11 : 79-91.