Category: Poster Presentation

Quantitative Mapping of Male Traits Affecting Female Longevity and Fecundity in C. Remanei

Presenter: Emily Ebel, Biology

Poster: A-8

Mentor: Patrick Phillips, Biology

Differing reproductive interests between the sexes can manifest in surprising ways, including a conflict, or tradeoff, between female reproductive effort and longevity. In some species, including the soil-dwelling nematode Caenorhabditis remanei, the act of mating has been demonstrated to reduce female lifespan by up to 50%. Interestingly, males from different genetic backgrounds affect female longevity—and fecundity— to varying degrees. To understand the genetic basis of these differences, and why they may have evolved, I am cataloguing the effects of males from 30 unique C. remanei strains on female lifespan and reproductive output. When this phenotypic data is combined with Restriction site Associated DNA (RAD) marker data from each line, I will be able to generate a Quantitative Trait Loci (QTL) map to approximate a genomic region that may be responsible for the male effects. Gaining this insight into the “battle of the sexes” in C. remanei will elucidate how sexual conflict, as an evolutionary force, can shape the morphology and behavior of many animals.

Determining roles of Wnt signaling in mammalian heart valve development

Presenter: Andrew Mckay, Biology

Poster: C-2

Mentor: Kryn Stankunas, Institute of Molecular Biology

Heart defects occur in 2% of live births, and of these, valve defects are the most common. By studying normal heart valve development we hope to find the genetic causes of these defects. Our primary question is: what signals direct the remodeling of embryonic heart valves into thin, elongated leaflets? We hypothesize that local Wnt signals direct heart valve remodeling by regulating cell proliferation and morphogenesis through activation of the NFATc1 transcription factor. To accomplish this, we use transgenic mice that allow us to block Wnt signaling during narrow time windows of embryogenesis. We inject transgenic mice with doxycycline, a molecule that causes the transgenes to temporarily express the Wnt antagonist Dkk-1 and inhibit Wnt signaling in particular cell types. I helped determined which of three transgenic lines best inhibits Wnt signaling and produces the most consistent and robust phenotype for valve defects. This line will be used for future experiments in which we will stain the sections for various cell type markers, indicators of proliferation, and localization of the transcription factor NFATc1. We will then use these results to determine if Wnt signaling affects cell proliferation and NFATc1 localization in targeted cell types in the developing valve.

What is the genetic basis of evolution? Looking at the shape of the opercle bone in Alaskan stickleback fish

Presenter: Christina Wickman, Marine Biology

Poster: D-4

Mentor: Chuck Kimmel, Institute of Neuroscience

What is the genetic basis of evolution? For this study, we used the three spine stickleback fish, which is a model for evolution as both the ancestral and derived populations can be gathered, and crossed to form viable offspring. Our study concentrated on the facial bone known as the opercle and we hypothesized that the shape of the opercle was controlled by Mendelian genetics in a co-dominance relationship. To test this hypothesis a model was created and both the parent and F1 populations were land marked choosing 12 points along the bones edge and the variation between the points were graphed using Principle Component Analysis. From the land marking of the F1 progeny it appeared that the alleles were expressing a dominance relationship and based on our findings we revised our hypothesis proposing this. To test this hypothesis the F2 progeny were landmarked, but did not show a dominance relationship, so we again revised our hypothesis proposing that quantitative genetics are at work: where multiple genes are acting to form different regions of the opercle bone. From this we concluded that the opercle shape is specified by multiple genes acting on different areas of the bone and we can infer that the changing of these genes provides the basis for evolution of the opercle, which provides for more skeletal variation, which can be advantageous evolutionarily

Genomic News From an Old Fish: Understanding Gene Regulation by Sequencing the Genome of a Living Fossil, the Spotted Gar (Lepisosteus oculatus)

Presenter: Margo Werner, Biology

Poster: D-3

Mentor: Ingo Braasch, John Postlethwait Biology

Cis-regulatory elements (CREs) are important regions of the genome that modulate the expression of nearby genes. However, their role in the evolution of genes is not yet well understood. To examine the function and evolution of CREs in fish, we study the spotted gar (Lepisosteus oculatus). The gar is a ‘living fossil’ that diverged from teleost fishes just before a teleost-specific whole genome duplication. Comparing the genome sequence of gar to teleosts allows us to investigate the appearance of CREs in relation to this genome duplication. We screen a genomic library of the gar in order to find regions of the genome containing developmentally relevant genes and their CREs. These genomic regions are then sequenced using next generation sequencing techniques. The results will potentially help us to understand the evolution of gene regulation in fish.accurate indicators of ancient local species distribution.

Glazing Peanuts

Presenter: Katharine Dwyer, Ian Austin, Aidan Tart, Architecture

Poster: A-7

Mentor: Allison Kwok, Architecture

In our consumer society the ultimate and most lasting product is, without a doubt, the landfill. We produce massive amounts of materials and products that have a functional lifespan of a month or a year and then discard them as waste to decompose for hundreds or thousands of years. Our goal is to discover which materials can be reused so that such destructive cycles can be slowed or even reversed. Responding also to the inefficiency of buildings, we have honed in on Styrofoam. We believe that this material, which is otherwise thrown away, can be used to add insulative value to double pane windows. During the night, hot days, or whenever views are not desired, Styrofoam peanuts would drop from within storage units in the walls to fill the gap between the panes of glass to add extra insulation. We tested our theory by building a custom hotbox that contained a 3” double paned window section in the center. With the help of HOBO data loggers, we then tested for the insulative value of our window with and without Styrofoam peanut filler. Our tests resulted in an insulative value of the Styrofoam peanuts to be about R-8, a significant improvement over the glass panes alone. Glazing makes up a significant percentage of a building envelope, and is a main source of heat loss for a building. By implementing simple insulative technologies such as this, great amounts of energy can be saved with virtually no effort or sacrifice.

Climate Change and Preservation Bias in the Pliocene Ringold Formation

Presenter: Christina Wilson, Geology

Poster: D-5

Mentor: Samantha Hopkins, Geology

Before oscillations of glacial and interglacial cycles began, the climate within the Pliocene epoch, (5.3 – 2.6 Ma) was relatively temperate –similar to more conservative projections for the next 100 years of our current climate. Therefore, this time period provides an excellent basis for predicting how present fauna may respond to climate change. This study compares sites with different geologic ages but similar locations to examine faunal changes over time. This will show how different factors, including climate, impact the ecosystem. I researched the Ringold Formation, located in South-Central Washington, which is early Blancan in age (4.75-1.80 Ma) and within the Pliocene epoch. I picked fossils from screened sediment, identified different types of fossil, and classified those most amenable to identification. One of the main components of the collection is Mimomys teeth. Classification of 419 teeth shows that the morals are not in the same proportions as in living Mimomys, suggesting preservation bias and highlighting the importance of sampling all members of an ecosystem. Rabbit and squirrel teeth were also classified. These were fewer in number, so conclusions could not be drawn as clearly. Further identification and cataloguing of species will enable a fuller picture of the environment preserved and continue to shed light on the changing fauna through time.

The Use of Gateway® Cloning and Modified BAC Trangenesis to Study Zebrafish Craniofacial Development

Presenter:Wade Sugden, Nathan Johnson, Biology

Poster: C-8

Mentor: Mark Sasaki, Institute of Neuroscience

Transgenesis techniques have revolutionized the study of cellular, developmental, and molecular biology by allowing researchers to visualize the proteins they study and manipulate the expression of genes in vivo. Through the use of genetic regulatory elements, transgenes can be tailored to over-express genes of interest, label tissue-specific cell types, and express genes in atypical locations. When expressed in skeletal elements of the zebrafish (Danio rerio), transgenes can be used to explore cell behavior and the genetic pathways involved in craniofacial morphogenesis. Two methods in particular have streamlined the process of creating transgenic animals: Gateway®-mediated and BAC-mediated transgenesis. Here we discuss the use of both techniques to create zebrafish that express transgenes in craniofacial elements using the runx2b, sp7, col11a2, and sox10 promoters. These promoters were chosen because runx2b and sp7 mark bone at different time points during development, while col11a2 and sox10 serve as cartilage markers. In the future, these fish will be vital tools for conducting cell tracking experiments, distinguishing cell types, and expressing genes of interest in craniofacial structures to determine their function.

Investigating an Unusually Bright Variant of the Red Fluorescent Protein mKeima

Presenter: A.J. Risenmay, Biology

Poster: C-4

Mentor: Jim Remington, Physics, Institute of Molecular Biology

mKeima is a monomeric red fluorescent protein (λem¬¬max ~620 nm) that is maximally excited in the blue (λex¬¬max ~440 nm). This extraordinarily large stokes shift can be significantly reduced following chromophore deprotonation under acidic conditions. By designing mutants to exploit the varying excitation species of mKeima, our lab was able to develop a redox-sensitive red fluorescent protein to be used as a quantitative reporter of the thiol/disulfide status in reducing subcellular compartments. This ratiometric variant was identified as mKeima M159K_TDCC and was found to be unusually fluorescent under green light (580 nm). Further examination revealed that mKeima M159K_TDCC is colorless when expressed in the dark, but irreversibly becomes pink when exposed to blue light. Here we combine x-ray crystallography and fluorescence/absorption spectroscopic techniques to investigate the fascinating chemistry behind this mKeima mutant.

Determining the degree to which chloroplast genome copy number limits the expression of chloroplast genes

Presenter: Dylan Udy, Biology

Poster: D-1

Mentor: Alice Barkan, Institute of Molecular Biology

The relationship that exists between chloroplasts and the plant cells they occupy is very complex. Chloroplasts evolved from a cyanobacterial endosymbiont, and throughout evolution many of the ancestral bacterial genes have been transferred to the plant nuclear genome. The proteins from many such nuclear genes are sent back to the chloroplast where they perform a variety of functions. We identified a non-photosynthetic maize mutant that accumulates reduced levels of several chloroplast mRNAs. We showed that the causal mutation is a transposon insertion in a nuclear gene encoding a protein that is closely-related to bacterial DNA polymerase I. Angiosperm genomes include two closely related paralogs encoding this protein. These have been studied in Arabidopsis (a dicot plant), where they are dual-targeted to both the mitochondria and chloroplast and have redundant functions. I have shown that our maize mutant has a 10-fold reduction in chloroplast DNA but normal levels of mitochondrial DNA, suggesting that the two paralogs have become specialized for either chloroplast or mitochondrial DNA replication in maize (a monocot plant). I am using the maize mutant to investigate the degree to which the abundance of chloroplast DNA limits chloroplast gene expression. I have found that the abundance of some chloroplast mRNAs decreases in parallel with the abundance of chloroplast DNA, whereas the abundance of other mRNAs does not. These results show that different factors limit the expression of different genes in the chloroplast.

Genetic Interaction in the Developing Danio Rerio Jaw

Presenter: Braden Larson, Biology, Russian and Eastern European Studies (REES)

Poster: B-7

Mentor: Charles Kimmel, Institute of Neuroscience

Genes act in concert during animal development to form complex anatomical structures. For example, the jaw skeleton requires precise expression and interaction of a multitude of genes to develop correctly. Our research focuses on the gene endothelin-1 (edn1), which encodes a signaling molecule required for ventral jaw development in the zebrafish, Danio rerio. Because elements of the jaw remain in the edn1 mutant, we hypothesized that other genes function within the edn1 genetic pathway. To test this, we generated double mutant zebrafish, pairing the edn1 mutant allele with mutant alleles of candidate genes based on previous literature. We then analyzed the double mutant skeletons for evidence of genetic interaction, and discovered an enhanced phenotype in one of the double mutants. Specifically, mutants for edn1 and fibroblast growth factor-8a (fgf8a), a gene that encodes another signaling molecule, are missing a portion of their upper jaw, a phenotype not present in either single mutant. To investigate the cell biology behind this phenotype we imaged the cells that constitute the jaw precursor tissue in live transgenic zebrafish. Strikingly, the cells that give rise to this structure appear missing in double mutant fish. Furthermore, we used Fluorescent In Situ Hybridization to observe gene expression of edn1, fgf8a, and potential shared target genes in wild type and mutant embryos. We conclude that cross talk between edn1 and fgf8a signaling is required for development of the jaw skeleton.