Research Plant Physiologist
Purdue University, 715 W State Street
Conservation and restoration of Acacia koa, a valuable hardwood tree species endemic to the Hawaiian archipelago, populations is a concern that will be addressed from multiple angles. Two current projects are looking at the genetic determinants involved in the adaptation response exhibited by koa growing at varied elevations. Using cutting edge NextGeneration Sequencing (NGS) technologies, TropHTIRC researchers will be able to obtain genetic information that will help to differentiate varied populations at the level of the genome and gene expression levels as well as:
- Estimate the variation in genetics between koa populations in various regions of the Island. Acacia koa species have varied responses to climate fluctuations when grown at different elevations. It is necessary to evaluate which genes are responsible for improved survival characteristics in light of a changing climate;
- Perform a comparative analysis of koa that have developed figure to those trees that have not developed figure. Isolation and characterization of particular wood formation genes differentially regulated between the two samples may help determine the genetic basis of figure within koa wood.
My research interests are focused on comparative analysis of differentially expressed genes related to abiotic stress tolerance and wood formation in tropical hardwood populations. My methodologies involve use of in silica, ex vitro, and molecular-based data acquisition aided by field experimentation.
Previous research efforts in this field involved three distinct topics:
- Drought tolerance and water-use efficiency in poplar using stomatal density manipulation;
- Overexpression of an Arabidopsis salt tolerance gene in poplar;
- Alterations of cuticular wax gene expression to improve abiotic stress tolerance.
Prior to a career in forestry, research efforts were based in human genetics and neuroscience. The topics of interest consisted primarily of human disease conditions. I gained experience working with a variety of model research organisms.
Selected research topics are listed below:
- Characterization of genes affecting brain neuronal development using embryonic dissections for in situ hybridization experiments in G. gallus and M. musculus;
- Generation of mutants in D. rerio by artificial in vitro fertilization to study Osteogenesis Imperfecta (Brittle Bone syndrome);
- Use of whole-mount in situ hybridization and morpholino injections of M. musculus and D. rerio to study Bardet-Biedl Syndrome;
- In silico analysis of a homologue of the human glaucome gene myocilin when microinjected into C. elegans.
While these research topics are highly divergent from my current work, the techniques, qualitative and quantitative skills, and my overall work ethic have served as a solid foundation for my current research.
PUBLICATIONS (from past research)
- Gerdes JM, Zaghloul NA, Leitch CC, Lawson SS, Mitsuma N, Tan PL, Menezes LF, Hill J, Kato M, Beachy PA, Beales PL, Germino GG, Fisher S, and Katsanis N. 2007. Disruption of the basal body compromises proteasomal function and perturbs intracellular Wnt response. Nature Genetics 39:1350-1360.
- Badano JL, Leitch CC, Ansley SA, May-Simera H, Lawson SS, Lewis RA, Beales PL, Dietz HC, Fisher S, and Katsanis N. 2006. Dissection of epistasis in oligogenic Bardet–Biedl syndrome. Nature 439:326-330.
DOI's from publications where my technical assistance was acknowledged but I did not participate in the writing of the manuscript.
Why This Research is Important
Acacia koa A. Gray (koa) is a tree species endemic to all of the islands within the Hawaiian archipelago but only exists in populations of sufficient size to be called forests on Hawai'i, Kauai, Maui and Oahu. Free-range cattle grazing and over-harvesting combined with invasive grasses have severely crippled koa forests to a point where populations are continuing to decline despite several small-scale restoration efforts. Koa populations also vary along elevational transects thus attempts to determine which genetic components allow specific trees to survive conditional intolerable to other memebers of the species are urgenly needed. Climate change, invasive species (both flora and fauna), and over-harvesting have combined to severely impact koa populations. Additional research is desperately needed for the sake of the tree species, the endangered animals that depend on these trees for survival, and the native islanders that depend on the highly-prized, figured wood for their livelihood.
- Purdue University, Molecular Tree Physiology (Genetics) , 2011
- Johns Hopkins University, Biotechnology (Biodefense) , 2006
- Morgan State University, Biological Sciences (Major(s): Biology/Chemistry Minor(s): English/Spanish) , 2001
- Research Plant Physiologist, USDA Forest Service @ Purdue University
2011 - Current
Use NextGeneration Sequencing to analyze RNA transcript profiles for variation in gene expression. Examination of expression profiles within and among populations at various elevations will generate data related to environmental adaptation. A second project seeks to identify genes related to figured wood formation. Current research model is the tropical hardwood tree koa (Acacia koa).
- Graduate Research Assistant / Teaching Assistant, Purdue University
2007 - 2011
Used genetic engineering to create transgenic models for the study of abiotic stress genes. Particular stresses examined were salt and drought stress. The research models used were Arabidopsis (A. thaliana), poplar (Poplar spp.), and green ash (F. pennsylvanica).
- Laboratory Manager, Johns Hopkins University
2006 - 2007
Performed in situ hybridizations and embryonic dissections to help in the characterization of genes affecting brain neuronal development. Maintained and genotyped the mouse colony (>1,000 individuals) and assisted in the generation of research manuscripts. The research models were chick (G. gallus) and mouse (M. musculus).
- Laboratory Manager, Johns Hopkins University
2002 - 2006
Performed in vitro fertilizations in addition to whole-mount in situ hybridization and morpholino injections to study Bardet-Biedl Syndrome (in M. musculus) and Osteogenesis Imperfecta (in D. rerio). The research models were mouse (M. musculus) and zebrafish (D. rerio).
- Laboratory Technician, Morgan State University
2000 - 2002
Studied a homolog of the the human Glaucoma gene (Myocilin). Research involved in silico analysis of the C48E7.4 gene, generation of cloning vectors, and microinjections. The research model was the nematode C.elegans.
- American Society For Plant Biology (Aspb), General Member (2009 - Current)
- Society For The Advancement Of Chicanos And Native Americans In Science (Sacnas), General Member (2007 - Current)
- Society For In Vitro Biology (Sivb), General Member (2010 - 2013)
- American Society For Cell Biology (Ascb), General Member (1999 - 2003)
- Society Of Toxicology (Sot), General Member (1999 - 2003)
Featured Publications & Products
- Lawson, Shaneka S.; Pijut, Paula M.; Michler, Charles H. 2014. Comparison Of Arabidopsis Stomatal Density Mutants Indicates Variation In Water Stress Responses And Potential Epistatic Effects.
- Lawson, Shaneka S.; Pijut, Paula M.; Michler, Charles H. 2014. The Cloning And Characterization Of A Poplar Stomatal Density Gene.
- Lawson, Shaneka S.; Pijut, Paula M.; Michler, Charles H. 2013. Species Selection In Hardwoods Research: Variations In Baseline Physiological Responses Of Select Temperate Hardwood Tree Species.
- Pijut, Paula M.; Lawson, Shaneka S.; Michler, Charles H. 2011. Biotechnological Efforts For Preserving And Enhancing Temperate Hardwood Tree Biodiversity, Health, And Productivity.
- Lawson, Shaneka S.; Michler, Charles H. 2014. Overexpression Of ATSto1 Leads To Improved Salt Tolerance In Populus Tremula × P. Alba.
- Pijut, Paula M.; Beasley, Rochelle R.; Lawson, Shaneka S.; Palla, Kaitlin J.; Stevens, Micah E.; Wang, Ying. 2012. In Vitro Propagation Of Tropical Hardwood Tree Species A Review (2001-2011).