Trustworthiness is an invariant characteristic that is independent of changes in emotional expressions. However, the perception of trustworthiness is highly varied and is not often accurately portrayed. As an attempt to understand what causes variations in perceived facial trustworthiness, participants were asked to rate trustworthiness of facial expressions (sad, happy, neutral) presented individually and as a single unit. Results found participants viewed happy expressions as more trustworthy, but when presented with all emotional expressions, neutral expressions were more likely to be used as an indication of trustworthiness. Overall, this study suggests neutrality is a better indicator of personality traits.

CYCLOIDEA (CYC) is a member of the TCP family of transcription factors, whose name stands for TEOSINTE BRANCHED 1, CYCLOIDEA, and PROLIFERATING CELL FACTORS.  The members of this transcription factor family are involved in regulating plant growth and cell proliferation by binding to DNA. Previous studies show that CYC has duplicated at least twice in the core eudicot angiosperms and that the CYC2 paralog is involved in controlling flower symmetry. The goal of our research was to characterize duplications of CYC in Rhododendron, with the long-term goal of seeing how these duplications affect flower symmetry. To accomplish this task, we used the R. williamsianum genome sequence to design primers specific to each paralog in order to PCR-amplify the CYC genes from four Rhododendron species, representing two subgenera (Hymenanthes, Rhododendron). Amplified products were cloned and sequenced to recover all alleles. We used our Rhododendron sequences and sequences from the conserved TCP and R domains of other species as out-groups in a Bayesian analysis to reconstruct the gene tree. From this tree, we have identified 2 main duplications in Rhododendron CYC genes as seen in other core eudicots. We also found that the CYC2 paralog has undergone at least 2 gene duplications and that the CYC1 paralog underwent one. Future research will focus on finding when CYC2 duplications occurred in rhododendrons and determining if, where, and when these CYC2 duplicates are expressed in Rhododendron flowers.

We have obtained three epochs of observations of the nearby spiral galaxy, NGC 300, using the Chandra X-ray Observatory. Using this data, we searched for variability in the X-ray luminosity function (XLF) of NGC 300's X-ray point source population. When the entire X-ray source population was considered, the XLFs were best described by using a power law with a slope of ~0.6-0.7. However, the XLFs of intrinsically variable X-ray sources showed significant variability between observations, especially at low luminosities (< 10^37 erg/s). We created synthetic, variable X-ray sources to probe the characteristics of the X-ray point source population in NGC 300. In order to match the observations, our models required that the peak X-ray luminosity of variable sources are significantly lower than commonly assumed, which is characteristic of a mass transfer due to direct wind accretion at significantly sub-Eddington rates.

Flowering plants exhibit diverse forms of floral symmetry that represent many independent changes throughout their evolutionary history. The selective and genetic basis to these changes has provided scientists with a complex puzzle that Darwin once referred to as an “abominable mystery.” Recent genetic studies began to uncover the genetic causes for this mystery, revealing the presence of certain genes that show correlations with this evolutionary trend. One such gene, the CYCLOIDEA (CYC) gene, has been identified as a major contributor to changes of floral symmetry. We have found this gene in the sequenced genome of Rhododendron williamsianum where it has experienced multiple duplications. The goal of my research is to identify the main duplications in one of the CYC copies (CYC2) in the Rhododendron genus. I accomplished this by using polymerase chain reactions to isolate any CYC2 copies present in two species from each of the subgenera of Rhododendron: Hymenanthes, Azaleastrum, Therorhodion, and Rhododendron. I then used cloning and sequencing to obtain the sequences of the CYC2 copies from each of the sampled species. I will conduct a phylogenetic analysis of these sequences in order to reconstruct a gene tree that will display a summary of the main CYC2 duplications that have occurred in the genus and when they emerged. Preliminary results from four species sampled thus far show that two independent duplications in CYC2 have arisen in both Hymenanthes and Rhododendron. My expanded analysis, sampling species from additional subgenera, will provide a more thorough history of this gene and its duplications throughout the genus. This will allow for more robust testing for correlation between symmetry and gene duplication in the future.

Despite extensive research on the evolution of adaptation and diversification, the underlying mechanisms remain poorly understood. Thus far, studies have shown conflicting results, suggesting that evolution within a particular ecological niche can both constrain or encourage an organism's ability to diversify and access other niches. Further investigation of the processes that generate specialists and generalists may shed further light on the evolutionary forces that drive organisms toward wider or narrower niche space. In order to explore these evolutionary trajectories, I utilize a well-studied experimental system involving distinct phenotypic variants of bacterium Pseudomonas fluorescens SBW25 and its naturally associated bacteriophage SBW25Φ2. By evolving Φ2 on different, but closely related hosts, and comparing phage fitnesses in native and foreign environments (hosts), I plan to elucidate the effects of adaptation on the creation of specialists and generalists. Pilot experiments suggest that the bacterial hosts currently being used may not be different enough to produce a discernable effect. However, by using hosts with more distinct characteristics, I expect to find evolutionary tendencies towards specialization in fixed environments/hosts. The results of this project will contribute toward the knowledge of mechanisms adaptation and diversification, and more specifically, the evolutionary dynamics between hosts and parasites.

 1 in 600 people world-wide are diagnosed with polycystic kidney disease (PKD), which leads to reduced kidney function over time. A cure for PKD is not currently available, making it important that we find more effective therapies for this disorder. Our laboratory has successfully used pluripotent stem cells to generate kidney organoids that functionally model the physiology of the kidney. The goal of this study is to generate induced-pluripotent stem (iPS) cells, adult somatic cells which have been reprogrammed to an undifferentiated state, from individuals affected with PKD. The first step of the process is the isolation of the patient’s cells from hair and urine samples. We are then able to reprogram these disease-affected cells into iPS cells and later differentiate them into kidney cells to create a better model for the disorder and screen for novel drugs. The information we learn from this study will help us better understand how PKD progresses and improve its treatment. We also hope that one day we will be able to transplant healthy kidney cells back into their patients, eventually eradicating the need for kidney transplants.

More than 20 million Americans have some level of chronic kidney disease. With the constant deterioration of kidney function, treatments for this disease are in high demand. The only treatments available today include dialysis and kidney replacement. Unfortunately, these methods are not ideal due to a high dependency on the dialysis machine, long waiting lists, and possible rejection of the organ. Recently, protocols were developed that allow us to use pluripotent stem cells to generate kidney-like organoids. These organoids contain major structures of the nephron, the functional units of the kidney, which clean and filter the blood. For instance, podocytes, proximal tubules, distal tubules, and various cell types develop in these samples. This complexity that develops allows more accurate modeling of kidney disease than previous methods. A new protocol developed by our lab allows us to grow miniature organoids in microwells; this will allow us to perform large scale drug screens to search for treatments for various types of kidney disease. The miniature organoids were tested to see if they replicate the complexity seen in larger wells. Immunofluorescence was used to characterize the kidney organoids and the different cell types present within them. Additionally, proteins with the capability to perform biological functions, such as transporting glucose and other ions, are able to be studied as well. The results were compared to human fetal kidney tissue. The miniature organoids replicate all of the same structures found in the larger wells. Because of the strong similarities between miniature kidney organoids and the human kidney, they are optimal for drug testing. Impacts associated with new therapies will be easier to monitor through the miniature kidney models.

As our planet warms, organisms that cannot migrate to more suitable habitats will be forced to adapt to the increasing temperatures or face extinction. An important question to address is how the rate of environmental change affects an organism’s chance to adapt. If an environment changes suddenly, then organisms must also adapt rapidly, whereas slower rates of change allow the organism more time to adapt. Microorganisms, such as the virus phi-6, can be utilized to answer this question because they evolve rapidly, allowing us to watch evolution in real time. We evolved phi-6 over 11 weeks to survive high temperatures. In different treatments, the viruses experienced sudden, moderate, or gradual changes in temperature. Sequencing the evolved lineages at two genes revealed multiple mutations. We added the mutations one by one to the ancestor to determine how each mutation affects thermotolerance. We find that each mutation can increase or decrease thermotolerance by a different amount. Interestingly enough, mutations that give the greatest increase in thermotolerance appeared in viruses that experienced slower temperature change. There is also a trend where viruses that experienced slower temperature change had more mutations per lineage than viruses that experienced sudden change in temperature. My results demonstrate that rate is an important parameter when taking adaptation into consideration. If the temperature increases too rapidly, there may be fewer ways for organisms to adapt, and they are unlikely to survive climate change.

Antibiotic resistance in bacteria is rapidly rising and our garrison of effective drugs keeps dwindling. As the creation of new antibiotics is incredibly time-consuming and expensive, it’s crucial that we slow the rapid evolution of drug resistance to prolong the effectiveness of our current drugs. Recent studies suggest improving current drug cycling practices by exploiting a phenomenon known as collateral sensitivity, where resistance to one drug leaves bacteria more sensitive to a second. By selecting pairs of antibiotics that exhibit collateral sensitivity, this method causes one drug to become more effective at abolishing bacteria after resistance to another drug has occurred. However, it is not known if collateral sensitivity profiles are maintained after further evolution of the bacteria; information that is crucial if we want a long-term method of combating drug resistance. Through our experiments, we aim to test the null hypothesis that collateral sensitivity profiles do not change over evolutionary time. To do this, we first isolated an array of Gentamicin-resistant Escherichia coli that exhibit collateral sensitivity to Colistin. Then we evolved our resistant bacteria for ~200 generations and measured the minimum inhibitory concentration (MIC), the concentration of drug that inhibits bacterial growth, for both drugs. By comparing the MIC values before and after our evolution experiment, we can determine if collateral sensitivity changes. If collateral sensitivity increases after evolution, collaterally sensitive drug cycling treatments could prove to be more effective than we already assume. But if collateral sensitivity decreases, the efficacy of this style of treatment may be reduced, which is important to know when designing drug cycling treatments. Knowledge of collateral sensitivity patterns will influence the way we treat patients and combat future multidrug-resistant bacteria.

Genetic robustness is the ability of an organism to gain mutations without changes to its fitness or functions. Evolutionary conditions that might select for genetic robustness are unclear, but some studies suggest that proteins that are more thermostable (able to fold properly at high temperatures) are also genetically robust to mutations. We are examining this relationship in phi-6, a virus that infects bacteria. We have evolved phi-6 for thermostability by subjecting it to high temperatures and then sequenced the viruses for mutations. We used homology-modeling programs to visualize the structures of mutated viral proteins and made predictions about the molecular basis of thermostability and genetic robustness. In order to evaluate whether the thermostable strains are genetically robust, we ran random mutagenesis on both thermostable mutants and the wild type virus. Our work shows that evolution for thermostability may be a viable mechanism to evolve genetic robustness.

One of the leading causes of depression is stress, and yet not enough is known about the exact mechanism by which stress alters depression. Of the four opioid receptor systems (mu, delta, kappa, and opioid receptor like-1), the kappa opioid receptor (KOR) is what my research focuses on. KOR is activated by its endogenous ligand, dynorphin. This is responsible for promoting analgesia, and depression-like phenotypes such as swim-stress immobility. The mammalian target of rapamycin (mTOR) is a protein kinase involved in regulation of functions such as cell growth, and metabolism. When dysregulated, it may lead to obesity, depression or cancer. Both mTOR and KOR have been shown to independently regulate stress-induced depression. However, there are no studies which tie these two ideas together. One possible link could be the stimulation of p38 MAPK kinase. Stimulation of KOR causes G-protein coupled receptor kinase (GRK)-dependent activation of the p38. Additionally, it is known that p38 causes the inhibition of TSC2, promoting phosphorylation of mTOR. Based on our results, activation of KOR with U50,488 causes an increase in phosphorylation in mTOR in vitro. However, this is also present in negative control cells not expressing KOR, which could indicate that U50,488 also has an off-target effect on a non-KOR mediated pathway. A similar treatment on mice decreases phosphorylation of mTOR after 28 hours in the brain, indicating that after a stressful event, mTOR activation is transient and acute. Furthermore, decreased mTOR phosphorylation after 28 hours in the brain was found to be blocked in GRK3 knockout mice. This implies that decreased mTOR phosphorylation after 28 hours with U50,488, requires the GRK gene. Further experiments, including behavioral testing, will be needed to investigate a deeper relationship between KOR and mTOR. With further research, these studies may lead to developing novel anti-depressants, revolutionizing depression treatment.