David W Galbraith

David W Galbraith

Professor, BIO5 Institute
Professor, Biomedical Engineering
Professor, Plant Science
Primary Department
Contact
(520) 621-9153

Work Summary

Work Summary
I examine the molecular functions of the different cells found in the tissues and organs of plants and animals and how they combine these functions to optimize the health and vigor of the organism.

Research Interest

Research Interest
David Galbraith obtained undergraduate and graduate degrees in Biochemistry from the University of Cambridge, and postdoctoral training as a NATO Fellow at Stanford University. His first academic appointment was at the University of Nebraska Lincoln, and he became Professor of Plant Sciences at the University of Arizona in 1989. His research has focused on the development of instrumentation and methods for the analysis of biological cells, organs, and systems. He is internationally recognized as a pioneer in the development and use of flow cytometry and sorting in plants, developing widely-used methods for the analysis of genome size and cell cycle status, and for the production of somatic hybrids. He also was among the first to develop methods for the analysis of gene expression within specific cell types, using markers based on Fluorescent Protein expression for flow sorting these cells, and microarray platforms for analysis of their transcriptional activities and protein complements. Current interests include applications of highly parallel platforms for transcript and protein profiling of minimal sample sizes, and for analysis of genetic and epigenetic mechanisms that regulate gene expression during normal development and in diseased states, specifically pancreatic cancer. He is also funded to study factors involved in the regulation of bud dormancy in Vitis vinifera, and has interests in biodiversity and improvement of third-world agriculture. He has published more than 180 scholarly research articles, holds several patents, was elected a Fellow of the American Association for Advancement of Science in 2002, and serves on the editorial board of Cytometry Part A. He is widely sought as a speaker, having presented over 360 seminars in academic, industrial and conference settings. He was elected Secretary of the International Society for Advancement of Cytometry in 2016. Keywords: Plant and Animal Cellular Engineering; Biological Instrumentation; Flow Cytometry and Sorting

Publications

Brown, J. K., Lambert, G. M., Ghanim, M., Czosnek, H., & Galbraith, D. W. (2005). Nuclear DNA content of the whitefly Bemisia tabaci (Aleyrodidae: Hemiptera) estimated by flow cytometry. Bulletin of Entomological Research, 95(4), 309-312.
BIO5 Collaborators
Judith K Brown, David W Galbraith

PMID: 16048678;Abstract:

The nuclear DNA content of the whitefly Bemisia tabaci (Gennnadius) was estimated using flow cytometry. Male and female nuclei were stained with propidium iodide and their DNA content was estimated using chicken red blood cells and Arabidopsis thaliana L. (Brassicaceae) as external standards. The estimated nuclear DNA content of male and female B. tabaci was 1.04 and 2.06 pg, respectively. These results corroborated previous reports based on chromosome counting, which showed that B. tabaci males are haploid and females are diploid. Conversion between DNA content and genome size (1 pg DNA = 980 Mbp) indicate that the haploid genome size of B. tabaci is 1020 Mbp, which is approximately five times the size of the genome of the fruitfly Drosophila melanogaster Meigen. These results provide an important baseline that will facilitate genomics-based research for the B. tabaci complex. © CAB International, 2005.

Jiexun, L. i., Xin, L. i., Hua, S. u., Chen, H., & Galbraith, D. W. (2006). A framework of integrating gene relations from heterogeneous data sources: An experiment on Arabidopsis thaliana. Bioinformatics, 22(16), 2037-2043.
BIO5 Collaborators
Hsinchun Chen, David W Galbraith

PMID: 16820427;Abstract:

One of the most important goals of biological investigation is to uncover gene functional relations. In this study we propose a framework for extraction and integration of gene functional relations from diverse biological data sources, including gene expression data, biological literature and genomic sequence information. We introduce a two-layered Bayesian network approach to integrate relations from multiple sources into a genome-wide functional network. An experimental study was conducted on a test-bed of Arabidopsis thaliana. Evaluation of the integrated network demonstrated that relation integration could improve the reliability of relations by combining evidence from different data sources. Domain expert judgments on the gene functional clusters in the network confirmed the validity of our approach for relation integration and network inference. © 2006 Oxford University Press.

Galbraith, D. W. (2007). Analysis of Plant Gene Expression Using Flow Cytometry and Sorting. Flow Cytometry with Plant Cells: Analysis of Genes, Chromosomes and Genomes, 405-422.
Birnbaum, K., Jung, J. W., Wang, J. Y., Lambert, G. M., Hirst, J. A., Galbraith, D. W., & Benfey, P. N. (2005). Cell type-specific expression profiling in plants via cell sorting of protoplasts from fluorescent reporter lines. Nature Methods, 2(8), 615-619.

PMID: 16170893;Abstract:

To investigate the relationship between developmental events and gene expression, cell-specific resolution of gene activity is critical. Such high-resolution data have been difficult to obtain at a genomic level because cells first need to be isolated, and then sufficient amounts of mRNA must be collected, or subsequently amplified, for a large-scale profiling analysis. Genomics methods have tremendous potential to infer developmental circuits and, in combination with genetic tools, to discover the unknown downstream targets of known developmental regulators. We have developed a method that can be used to isolate up to hundreds of thousands of plant cells of a specific cell type, with very high purity, which can then be used for microarray analysis. The method makes use of reporter lines expressing green fluorescent protein (GFP) in histologically defined cell types, of which large collections are now available (Table 1). The GFP Line of interest is bulked and the tissue is collected and rapidly converted into protoplasts. GFP-positive cells are then isolated using a fluorescence-activated cell sorter (FACS). Total RNA is isolated, labeled using standard procedures and applied to microarrays (Fig. 1). The technique has been used to generate expression profiles of cell types and tissues in the Arabidopsis thaliana root, although it can be used for any tissue whose cell walls can be readily digested. The protocol presented here has been optimized for roots.

Galbraith, D., Gong, F. C., Giddings, T. H., Meehl, J. B., Staehelin, L. A., & Galbraith, D. W. (1996). Z-membranes: artificial organelles for overexpressing recombinant integral membrane proteins. Proceedings of the National Academy of Sciences of the United States of America, 93(5).

We have expressed a fusion protein formed between the avian infectious bronchitis virus M protein and the bacterial enzyme beta-glucuronidase in transgenic tobacco cells. Electron microscope images of such cells demonstrate that overexpression of this fusion protein gives rise to a type of endoplasmic reticulum membrane domain in which adjacent membranes become zippered together apparently as a consequence of the oligomerizing action of beta-glucuronidase. These zippered (Z-) membranes lack markers of the endoplasmic reticulum (NADH cytochrome c reductase and ribosomes) and accumulate in the cells in the form of multilayered scroll-like structures (up to 2 micrometers in diameter; 20-50 per cell) without affecting plant growth. The discovery of Z-membranes has broad implications for biology and biotechnology in that they provide a means for accumulating large quantities of recombinant membrane proteins within discrete domains of native membranes.