Photoperiod is utilized in plants to control seasonal responses such as flowering. Flowering of Arabidopsis is promoted in long day conditions (LD), late spring to summer, but not in short day conditions. Arabidopsis thaliana is our model organism because of its short generation time and simple genome which allows us to apply our findings to other species. One of the major factors that determines flowering time response to the different lengths of photoperiods is a gene, FLOWERING LOCUS T (FT). FT is induced around dusk in laboratory LD conditions. In natural LD conditions, there is an additional induction of FT in the morning. Although the molecular mechanism behind flowering regulation is the most characterized in Arabidopsis, the mechanism behind the expression of FT in the morning under natural LD conditions is not fully understood. Investigating these mechanisms will help us to understand how Arabidopsis plants flower in spring in nature and ultimately better the accuracy of experiments that are run indoors. The regulation of expression levels of transcription factors may be important for this FT induction. Through RNA sequencing analysis, we found eleven transcription factors within genes that were found to be differentially expressed between laboratory LD conditions and natural LD conditions. Analysis through quantitative polymerase chain reactions (qPCR) will hopefully yield results pointing toward a transcription factor that is important for the regulation of FT expression. 

Age-associated diseases, like neurodegenerative disease, cancer, heart disease, and metabolic dysregulation limit healthy human lifespan. In recent years, biologists researching aging and longevity have turned their attention towards maximizing healthspan, the healthy portion of one’s life before the onset of age-related disease. By delaying age-associated diseases, we can fundamentally improve quality of life globally. Natural products and other pharmacological interventions hold particular promise as interventions to extend healthspan and lifespan. We seek to identify novel compounds that extend lifespan using the invertebrate model system Drosophila melanogaster (fruit fly). We have tested an extract made from Pterocarpus marsupium (PME), a tree native to India and Sri Lanka with uses in Ayurvedic medicine. PME extends cellular lifespan in budding yeast, another invertebrate model system. We also tested pterostilbene, a compound found in Pterocarpus marsupium extract. As a positive control for lifespan extension, we are treating other cohorts of flies with rapamycin. Rapamycin is a specific inhibitor of the nutrient sensing mechanistic Target Of Rapamycin (mTOR) pathway, a known longevity regulating cellular pathway. Using multiple fly genetic backgrounds, performed a dose response to identify concentrations of PME and pterostilbene that extend Drosophila lifespan. Through pharmacological methods, we seek to delay aging and minimize human vulnerability to age-induced diseases. Discovery of specific compounds that prolong lifespan is a first step in developing therapeutic methods to delay human aging and health decline.

Heterotopia are organized structures consisting of mixed cellular and neuronal elements arranged in a clear architectural pattern inappropriate to the considered tissue. Heterotopia are observed in the cerebral cortex and the cerebellum as a feature of many neurological disorders yet the we know little about the mechanisms driving their formation. We have analyzed a substantial number of Dandy Walker malformation (DWM) human fetal cerebella and found that a significant number of cases contain heterotopia. DWM is the most common structural birth defect of the human cerebellum and is characterized by an enlarged posterior fossa, enlarged fourth ventricle, and cerebellar vermis hypoplasia. A subset of cases are caused by loss of FOXC1, a transcription factor expressed in the mesenchyme during development. Our group has previously shown that loss of FOXC1 in mice causes loss of the mesenchyme-secreted factor SDF1alpha. Further, loss of SDF1alpha is sufficient to cause cerebellar heterotopia. This emphasizes the importance of mesenchymal signaling in the maintenance and development of the clear laminar architecture of the mature cerebellum. We hypothesized that granule neuronal progenitors (GCPs) are the primary cellular target of SDF1alpha mesenchymal signaling and therefore the main cell type causing heterotopia formation. To test our hypothesis, we excised the receptor for SDF1alpha from just GCPs in mice. Our findings show that loss of SDF1alpha in GCPs causes them to prematurely migrate into the developing cerebellar anlage and also caused other cerebellar cell types to form structured heterotopia. We observed defects in cerebellar foliation in the treatment group. Our data emphasizes the importance of SDF1-alpha dependent mesenchymal signaling in cerebellar development and identifies heterotopia as a new phenotype in DWM.

Dandy Walker malformation (DWM) is the most common human cerebellar malformation, affecting 1 in every 3000 live births. DWM is an imaging diagnosis that is characterized by three features: cerebellar vermis hypoplasia, an enlarged posterior fossa, and an enlarged fourth ventricle. Although recent advances in neuroimaging have improved diagnosis of DWM, virtually nothing is known about the cellular and histological defects that lead to DWM. One major reason is that little human specific data is available describing the histology of normal and abnormal human fetal cerebellar development. Currently, there is limited published fetal pathology of DWM. There is no comparative analysis available and most studies are confounded by lack of molecular confirmations of diagnoses. We have carried out the first comprehensive histo-pathological analysis of human DWM. Such histo-pathological analysis, that I specifically was responsible for completing, included measuring the length and cell density of certain regions of the developing cerebellum in the 36 DWM cases, such as the external granule layer and the rhombic lip. Our results indicate a significant reduction in size and area of neuronal progenitor zones in the developing human cerebellum. We also observe aberrations in the developmental trajectories of specific cell types like Purkinje cells, and progenitor zones like the rhombic lip. Through our analysis of the human fetal DW cerebellum, we begin to directly address the developmental pathology of human DWM beyond that of the mouse models that share similar pathology. We believe our studies will fundamentally improve our view and understanding of the biology of the human cerebellar development and give us insights on the developmental pathogenesis of DWM.

Alzheimer's disease (AD) is the most common cause of dementia, a general term for memory loss and other cognitive abilities. Although this disease has been a major research focus since the 1980s the pathologic mechanisms are still not understood, and therapeutic interventions have been ineffective. The most definitive method for classifying AD is through identifying accumulations of toxic proteins amyloid-beta and tau proteins in post-mortem brain tissue. Dr. Su-in Lee’s lab has developed a machine learning method that integrates the pathological tau phenotypes with gene expression levels in the same brain tissue. This analysis highlights the genes with expression level changes that correlate with the pathological protein aggregation phenotypes. For this proposal I will directly test the impact of these candidate genes on cellular pathologies resulting from aggregating human tau protein with a new C. elegans AD model in which human tau is expressed in the worm’s muscle. This tau expression will likely result in premature paralysis because previous nematode AD models with human amyloid-beta have shown this phenotype. The results of my genetic screening will lead to a better understanding of the human genes that are dysregulated in human AD brains and provide a basis for genetically-dissecting the pathways that influence the mechanisms of tau toxicity.

Understanding how genetic variation shapes phenotypic variation for complex quantitative traits is fundamental to developing more accurate disease prognoses and therapeutic interventions. Genes that are important in early development contribute to adult quantitative traits, such as height, vision, and health. The fruit fly Drosophila melanogaster is a model organism for studying complex traits, such as aging. Drosophila possesses many well-developed genetic tools and shares evolutionarily conserved age-regulating pathways with our species. One such conserved pathway is the mechanistic Target Of Rapamycin (mTOR) nutrient signaling pathway. Rapamycin is a specific allosteric inhibitor of mTOR signaling that extends lifespan in adult Drosophila melanogaster and delays development in larvae. However, the functional explanation for these effects is incomplete and a genetic association between development and lifespan is unknown. We used the Drosophila Genetic Reference Panel (DGRP), a highly inbred fruit fly population representing natural genetic variation, to measure rapamycin-mediated developmental delay. We used these data to carry out a Genome Wide Association Study (GWAS), and combined our data with data from a screen for the effects of rapamycin on lifespan in the DGRP, also carried out in our lab. GWAS analysis will help us to identify genetic variants associated with rapamycin efficacy and to discover novel variants associated with developmental timing. By connecting lifespan and development genetically, we identified shared candidate genes that modify these two very different molecular genetic programs. Accomplishing this is the first step towards identifying early life biomarkers that are predictive of rapamycin success as a longevity intervention in later years. These pharmacogenomic analyses advance a precision medicine approach where interventions are tailored towards genetic background to maximize human health.

This research focuses on using advanced surveying techniques as well as hand mapping to analyze force distribution during laboratory impacts of man-made projectiles into ice. This is done in the hopes of characterizing substrate damage surrounding an impact crater created by a proposed hard landing system. Knowing where these different deformation zones occur is useful in determining where the lander could sample. The landing system, the Subsurface Ice Plume Sampler (SIPS) utilizes ejecta (broken up debris thrown from the crater) to create a transient atmosphere - decelerating a secondary instrument package through momentum transfer. Small-scale experiments were done on one-ton buckets of ice using scale-sized projectiles. Between two hundred and five hundred images used to 3D models of the ice craters using the structure from motion imaging technique. Hand mapping of the deformation zones (areas of different types of fractures) was conducted to compare to the 3D model to help show the directionality of force distributions through the crater. Using both the 3D models and a hand mapping analysis of the craters, we were able to determine that the crater shapes were atypical. In a typical crater, the force disperses radially outward from the impactor; however, we determined that the majority of the force was focalized directly below the impactor. Future work includes using Rhinoceros 3D computer software to quantitatively analyze each crater’s individual morphology, curvature, and volume and compare them to traditional impact craters.

Whispering Gallery Mode (WGM) sensors have unprecedented sensitivity in the optical detection of label-free biomolecules. These sensors can detect surface adsorption and have been used to detect single molecule adsorption and interaction processes. By observing resonance shifts during molecular interactions, WGM sensors can characterize a molecule’s surface adsorption. The goal of this project is to develop a robust WGM dip sensor array controlled by a three-axis stage in order to perform high-throughput characterization of peptide binding and adsorption within a 96-well plate format. The peak of spectral absorbance is the WGM resonance, and as this changes with surface adsorption we measured a spectral shift. Using this spectral shift in combination with the known concentration of our peptide species, we determined binding kinetics. The WGM sensor was used to characterize different peptide sequences to further understand the effects of peptide mutations on binding kinetics. A single microsphere resonator was used as proof of principle and will eventually be adapted to an array of eight WGM microsphere resonators to generate large amounts of data. This high throughput approach will provide the much needed large amount of quality data that is necessary for the development and adaptation of machine learning and applied statistical analysis algorithms toward the eventual development of artificial intelligence platforms in material science. The project is supported by NSF-DMREF through the Materials Genome Initiative.

Embryonal rhabdomyosarcoma (ERMS) is a devastating pediatric cancer that affects soft tissue such as skeletal muscle and connective tissue. Currently, there is no effective treatment for patients with ERMS. Mutations in the gene PTPN11 are found to have cancer-promoting roles in leukemia, lung, and breast cancers, but its role in ERMS is virtually unknown. PTPN11 codes for the SHP-2 protein, which is a component of the RAS/MAPK (mitogen-activated protein kinase) signaling pathway. Abnormalities in this pathway are known to transform normal cells into cancer cells when certain proteins are upregulated. My central hypothesis is that PTPN11 promotes RMS tumor growth by allowing cells to proliferate and differentiate out of control. To test the hypothesis, I used CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas gene editing technology to disrupt PTPN11 gene function in two models. I designed constructs that express guide RNAs that target the PTPN11 locus in the zebrafish or human genome. If PTPN11 has a tumor-promoting role, I expect targeted disruption of zebrafish PTPN11, delivered via microinjection, to result in reduced RMS tumor formation and growth compared to zebrafish tumor with no PTPN11 gene disruption. In the human ERMS cell lines, I will use virus-mediated transfer to introduce the CRISPR DNA construct in vitro. My hypothesis will be supported if the cells harboring targeted disruption of PTPN11 have reduced growth and less self-renewal capacity compared to the control cells. My findings will elucidate the role of PTPN11 in RMS, which will allow further research into the potential therapeutic benefit of targeting PTPN11 in pre-clinical RMS models.

In this research, we looked at the possible use of an Air Breathing Pulsed Plasma Thruster (AB-PPT) for propelling an aircraft that could potentially act as an atmospheric satellite at atmospheric altitudes > 25 km. One of the advantages of operating at such altitudes is that the aircraft is not subject to highly variable weather conditions. An atmospheric satellite is an aircraft that can perpetually fly around the same area, and can be launched at significantly reduced cost when compared to conventional satellites while providing similar services such as communication and imaging. At the desired altitude, conventional blade-based propellers are too inefficient due to low background pressure, but it is still too low of an altitude for conventional space propulsion, prompting the use of AB-PPT. The AB-PPT is an adaptation of the conventional PPT which is a pulsed device that uses an electric discharge to ionize and expel the solid propellant such as PTFE at high speeds. For the AB-PPT, a large amount of voltage discharge generated across the two coaxial electrodes ionizes and expels the background air instead. In order to identify the most efficient AB-PPT design, three different configurations were tested using a pendulum-based thrust stand to measure the thrust efficiency, a Rogowski coil to measure the current per discharge, and high-speed video. One configuration has been identified, and we are currently investigating an alternative electric connection to further increase the amount of thrust per discharge. Future work includes plasma diagnostics of the AB-PPT such as Langmuir probe, and B-dot probe, in addition to the development of more robust electronics capable of delivering higher power, and the development of the final version of the AB-PPT for patenting purposes.

Electric propulsion is becoming an increasingly important field due to the rise of microsatellites in education, research, and industry. Because chemical propulsion is impractical for these small-scale satellites, the need for an efficient, long-term electric propulsion solution has become apparent. In response to this, the Dielectric Barrier Discharge (DBD) Thruster was developed. The DBD is a novel electric propulsion system that uses a low power input to ionize Argon gas and accelerate ions to produce thrust. For initial characterization, thrust values and plasma characterization parameters were collected in the far field of the plasma using electric propulsion diagnosics. The experiment was repeated for multiple operational spaces, and data was collected, compiled, and analyzed. Preliminary results indicate thrust values and plasma characteristics comparable to those of other propulsion systems at similar electrical power levels. Further testing with different high voltage parameters as well as implementing additional diagnostic equipment will help fully characterize the DBD system and assess its potential usefulness in a satellite architecture. To increase the versatility of the DBD system, research will be done on developing multi-DBD arrays and incorporating a nanoparticle injection system for demonstrating future space resource utilization.

Prior research has found that physical activity (PA) does not significantly predict academic achievement (AA) among college students. Studies have shown that PA buffers the effect of stress, while other studies have suggested stress has a negative impact on AA. Thus, stress can be a mediator of the relationship between PA and AA, which is commonly overlooked in studies. This study examines the mediation of stress in the relationship between physical activity and academic performance in college students. Behaviors incompatible to PA, such as TV and game/computer usage were also considered in the meditational analysis. For achieving this goal, 377 college students were recruited and completed a demographic survey and the State and Local Youth Risk Behavior Survey. The participants were 22.4 years old on average, predominantly female (76%), and mostly Caucasian (52%). In results, PA was significantly correlated to game/computer usage (r=-0.11, p<0.05), but not with TV usage (r=-0.03, ns). No significant direct relationship was found between PA and AA, but the indirect effect of PA on AA via stress was significant (z=-1.95, p<0.05). Likewise, game/computer usage had a significant indirect relationship with AA through stress (z=1.96, p<0.05). This indirect relationship was only significant in women (z=2.36, p<0.05), but not men. No significant direct and indirect effects were found for TV usage and AA. In conclusion, PA may enhance AA through its health and stress-reducing benefits. This provides an alternative explanation to prior research that couldn’t find a direct link between PA and AA; many different behavioral/psychological factors and their interrelationships need to be considered while investigating AA among students. Schools should consider ways to increase students’ physical activity such as using behavioral prompts on campus and increasing options for affordable transportation, thus reducing perceived levels of stress to enhance students’ academic performances.

Asteroid sample return has potential to impact research and how humans collect resources, but sample return missions remain prohibitively expensive and complex. We propose a device to retrieve a preexisting sample container from the surface of an asteroid or other extraterrestrial body, focusing on simplicity, repeatability, and reliability. Taking inspiration from a classical design, the bear trap, we created a functional 3D printed prototype, which is mechanical and capable of capturing a 1.5x15 in cylinder resting on a flat surface. Consideration was given to potential rocky terrain or an awkwardly positioned return container, and to sealing the sample container to prevent contamination upon return to earth. Future prototypes will be constructed from stronger, lighter weight materials and will be further developed during active field tests on debris at a penetrator impact site in Eastern Washington.

Our current research with the Kinematics and Impacts Lab at the University of Washington entails the design, buildup, and field testing of an asteroid sampling system. These field tests include the buildup of two stage closer rockets, which are highlighted in this presentation. This asteroid sampler field testing helps characterize the sampling process of impacting an asteroid at high speeds- necessitating our rocket system be capable of stable, high speed flight, even at an inverted trajectory. The booster stage, or primary stage, of the system consists of a single large motor to allow the system to reach between 3000-4000 feet above the ground. The sustainer, or second stage, consists of eight smaller motors clustered around a central body tube, allowing the second stage to be hollow. Finally, a hollow point steel nose cone caps the sustainer. Inside the nose come assembly a sample dive is attached, designed to eject during impact. Field testing of this system occurred in December 2018, with preliminary results being compiled.

This purpose of this project was to investigate the impact of a rocket penetrator for sample-return missions focused on Jupiter’s icy moon, Europa. In particular, primary analysis used the kinetic energy from the ejecta plume of the impact crater to halt the momentum of the primary payload to model the impact. To do so, steel alloy projectile impacts in a material with properties of ice (so as to simulate the surface of Europa) were simulated using ANSYS Autodyn computational dynamics software. ANSYS Autodyn makes use of both Lagrangian and Hamiltonian meshes, as well as smooth particle hydrodynamic mesh-less modeling with cross-coupling so as to best represent the impact of the projectile, the material deformation, and the projectile deformation. This analysis of elastic and plastic behavior, as well as bulk failure and separation, resulted in accurate depictions of deformation in both the projectile and target material, validating it as a model with the potential to simulate the impact of a Europa sample-return rocket penetrator. This analysis serves as a basis for future progress, and will soon be enhanced via further simulation in conjunction with ISAIL simulations so as to accurately depict the material deformation and ejecta plume. The data from these computer simulations can eventually be compared to physical experiments and field tests that are to be conducted under the University of Washington’s Kinematics and Impacts Laboratory (KILa).