MCDB










development of leaves
Timothy Nelson, Ph.D.

Timothy Nelson, Ph.D.

Professor of Molecular, Cellular & Developmental Biology
Email: timothy.nelson@yale.edu
Room: OML 253A
Phone: (203) 432-3860/ (203) 432-3861
Fax: (203) 432-5632

B.A. University of California, San Diego 1974; Ph.D. Stanford University 1980

Our current work is aimed at understanding the formation of the regular venation pattern that appears to guide leaf cell differentiation on a fine scale. We are identifying the genes and pathways that form the simple venation pattern of Arabidopsis leaves, using three experimental approaches: (1) identification of genes that correspond to vascular pattern mutants, (2) characterization of genes with provascular (PV)-specific expression patterns, and (3) analysis of expression profiles of PV cells by laser-capture microdissection (LCM) and microarray analysis. Many pattern defective mutants have been isolated in Arabidopsis,, including those with discontinuous or misaligned veins, open forked veins instead of closed loops, excessive vascular tissue, vascular islands, or parallel instead of netted venation. We have cloned several of the corresponding genes, which are members of signaling pathways and sterol biosynthetic pathways. Among genes with PV expression patterns, we identified a leucine-rich-repeat receptor kinase, VH1, that influences the differentiation of PV and neighboring cells. Although its activating ligand is currently unknown, VH1 interacts in vivo and in vitro with leaf-specific signaling partners, and its misexpression or knockout has developmental consequences in the leaf. In other studies, we are using LCM for the isolation of leaf PV cells, whose transient and dispersed existence during development has made them difficult to characterize. The resulting PV RNA and protein expression profiles will be invaluable in deducing the pathways that produce the patterns of veins. We are also engaged in preparing a comprehensive transcriptional profile atlas for all cell types of the rice plant, utilizing LCM and whole genome microarrays.

Key Past Publications

Kerk, N., T. Ceserani, S.L. Tausta, I. Sussex and T. Nelson (2003) Laser-capture microdissection of cells from plant tissues. Plant Physiol.132. 27-35

Carland, F.M., S. Fujioka, S. Takatsuto, S. Yoshida, and T. Nelson (2002) The identification of CVP1 reveals a role for sterols in vascular patterning. Plant Cell 14, 2045-2058.

Clay, N.K., and T. Nelson (2002) VH1: a provascular-specific receptor kinase that influences leaf cell patterns in Arabidopsis. Plant Cell 14, 2707-2722.

Publications (2003/2004)

Carland FM, Nelson T. Cotyledon vascular pattern2-mediated inositol (1,4,5) triphosphate signal transduction is essential for closed venation patterns of Arabidopsis foliar organs (2004) Plant Cell. 16, 1263-75. Epub 2004 Apr 20.

Meyers, B.C., D.W. Galbraith, T. Nelson, and V. Agrawal (2004) Methods for transcriptional profiling in plants: be fruitful and replicate. Plant Physiol., 135, 637-652

Teaching

MCDB 105a, An Issues Approach to Biology
MCDB 420b/615b Genetics and Molecular Biology of Plant Development

Committees and Editorial Boards

Director, Marsh Botanical Garden
NSF grant review panel
Review grant proposals for NSF, DOE and USDA, and SERC (Canada).
Review manuscripts for Science, Plant Cell, Plant Physiol., Development, others
Ph.D. committee at Cold Spring Harbor Laboratory
MCDB Building Committee (Chair from 7/04)
Dean's Endowed Postdoctoral Fellowship Selection committee
Packard Fellowship Selection Committee
Provost's Standing Advisory & Appointments Committee (FES)

Seminars and Scientific Meetings

Arabidopsis Conference, Madison, WI 19-23 June, invited speaker
Crowell & Moring LLP, Patent law firm, Washington, DC, 19 February
Web seminar (150 subscribers) Arcturus laser capture, 25 Sept
NYU Biology, 24 Nov
Agric. Sciences Univ., Bangalore, India, 5 Feb
Interdisc. Plant Program, Univ. Arizona Tucson, 22 March
Yale Rice Symposium, 30 April
CSHL Plant Development Course, invited lecturer, 17 July

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