Peter Melcher presented "The impact of xylem wounding on the measure of stem hydraulic resistance" at the Botany 2010 Conference in Providence, RI. August 2010. Co-authored with Steven Warchocki (Biology '09).
Abstract:
Plant performance is directly related to plant water status and because xylem hydraulic resistance impacts water supply to leaves it has been used to characterize plant adaptations to environment. Xylem tissue in plants contain both living and dead cells. The cells responsible for the mass flow of sap from roots to leaves are composed of numerous dead hollow conduits. The design of these dead conduits e.g.,
diameter, length and frequency of bordered pit junctions, greatly impact the resistance of sap moving through them. Measurements of xylem hydraulic resistance generally rely on perfusing solution through excised plant tissue. In this study, two non-trivial issues that greatly compromise our ability to fully characterize xylem properties in plants are discussed. The first issue is focused on the role of the living cells in meditating a xylem wound response that was found to increase stem hydraulic resistance by up to 80% in some tree species (in less than a few minutes from excision). Appropriate measurement protocols have been developed that greatly reduce the impact of xylem wounding on the measure of xylem hydraulic resistance. The second issue deals with the difficulty in measurement error that results from opening non-functional flow paths when hydraulic measurements are made on excised tissues that contain multiple years of xylem growth. Results from a new measurement protocol to deal with this issue will be discussed. These two new protocols should allow us to fine tune our estimates of xylem hydraulic resistance in plants. Also, these methods provide a tool to better understand plant response to xylem wounding, a physiological mechanism used by plants to protect and prevent the spread of pathogen invasion into their water conducting systems. Future studies aimed at understanding the role of both the living and dead cells in long-distance sap transport is pertinent in understanding the full influence that plant hydraulic form has on plant drought adaptations.
Leann Kanda presented a poster entitled, "Just gotta be me: Individual personalities in captive Siberian dwarf hamsters, Phodopus sunorus at the 47th Annual Meeting of the Animal Behavior Society in Williamsburg, VA. July 2010. Co-authored with Laura Louon and Kit Straley (both Biology '11).
Maki Inada presented "Genome-Wide Analyses of prp8 Alleles Implicated in the Two-State Model for Spliceosome Activitiy" at the RNA Society Meeting in Seattle, WA. June 2010. Co-authored with Jeffrey Pleiss.
Abstract:
Removal of noncoding introns from pre-rnRNA is catalyzed by the spliceosome, a large multi-component complex I that must be assembled anew for every splicing reaction. Splicing chemistry consists of two separate and sequential transesterification reactions: in the first step the branch site adenosine attacks the 5' splice site to produce the 5' exon and branched lariat intermediate; in the second step the 5' exon attacks the 3' splice site to produce the lariat intron and 1 spliced product. A two-state model for the spliceosome has been previously proposed, in which the conformations of the active site required for the first and second steps are in competition with each other (Query and Konarska 2004). Factors that modulate / and stabilize the first step result in inhibition of the second step and vice versa. A number of such opposiogprp8 alleles that affect the transition between the first and second step have been isolated and characterized to support this model (Query and Konarska 2004, Liu et al. 2007). To further investigate the role that prp8 plays in splicing activation, we have chosen to take two genome-wide approaches in Saccharomyces cerevisiae. First, we have conducted splicing-sensitive microarray analyses to determine the genes that are affected by each of these prp8 alleles. Second, we have taken a high through-put reverse genetic approach known as Synthetic Genetic h a y analysis to identify those factors that are involved in modulating the activity of these prp8 alleles. By determining both the transcripts affected and the complement of factors that genetically interact with each of these prp8 alleles, we will be better able to define how prp8 functions in the splicing pathway. Lastly, strategies for developing a research course for undergraduates utilizing these methods will be discussed.