POSTER #1:
Growth model of Nannochloris oculata and its significance to biofuel production
Chun Fang Cheng
Dr. Greg Mitchell
The SPG lab is mainly focused on microalgae in terms of growth models for various species and evaluating its potential as a solution for commercialized biofuel. The biggest question that researchers face right now is being able to design a consistent growth model for a specific species and be able to provide evidence that such growth model will succeed even in larger scale. The factors that need to be considered when designing a growth model are variations such as pH, salinity, media, temperature, light, nutrient, and turbulence. One major concern that researchers have is that cities are dumping wastewater concentrated with nutrients straight into the ocean. This causes great macroalgal growth along the shore and results in coral cover reduction and severe damages to marine environments. The lab’s proposed solution is to re-route these nutrient-concentrated wastewater and use it for microalgal growth. Because of the ability of microalgae to remediate and reuse some of the nutrients from the wastewater, the amount of macroalgal growth along the shore should greatly decline. Furthermore, the microalgae biomass that was generated from the wastewater can then be used to provide biofuel. Although this model appears to be limited at full scale at this point, it is a very promising solution once we have developed a low-cost and reliable process for algal growth. To contribute to the large research efforts of biofuel production, our project seeks to find the optimal growth models for Nannochloris oculata. The experiment designed allows for two different systems, one system at 15°C and one at 25°C. Within each system, 5 different subsystems are designed with various light levels. By comparing the growth level of N. oculata under these variables, we can determine the optimal growth conditions for the organism. Growth will be monitored via hemacytometer cell counts, in-vivo flourometric chlorophyll absorbance, extracted chlorophyll analysis, and CHN/POC analysis.
POSTER #2:
Effect of Electro-Chemo-Mechanical Stimulation on Stem Cell Fate
Jessica Chuang
Dr. Shyni Varghese
Signals arising from tissue environments have significant effects on stem cell fates, such as proliferation and differentiation. In this study, we have designed and developed a hydrogel system, comprising of charged and neutral polymer moieties, which can provide physiologically relevant dynamic physical cues to the cells. We then employed our hydrogel to evaluate the effect of microenvironmental factors on various cell functions. Specifically, we have investigated the effect of dynamic electrical signals on stem cell proliferation. It has been shown that dynamic bioelectric signals present within the extracellular spaces provide potential guidance signals for migrating and proliferating cells. Therefore, this study was based on the hypothesis that potential electrical differences across tissues play a pivotal role on the microenvironment of the cell, especially in controlling different aspects of cell proliferation. We have used both somatic as well as stem cells; chondrocytes and mesenchymal stem cells. 20 million cells were encapsulated in our hydrogels, and the cell-laden hydrogels were then subjected to an external electric field at 60mV for 20 second pulses, 1 minute pulses, and a 30 minute continuous current for half and hour. We observed an increasing trend in cell proliferation as the pulse length increased from 20 seconds to 30 minutes. We anticipate that these hydrogels, which support cell survival and growth, will open up a new avenue in evaluating the effect of complex microenvironmental factors on various cellular functions. Our future study will involve employing these hydrogels to evaluate the effect of electrical stimulation on stem cell differentiation.
POSTER #3:
The Rational Design of Predicted Neuraminidase Inhibitors for the Treatment of Swine and Avian Influenza
Daniel Dadon
Dr. Andrew McCammon
The World Health organization warns about the pandemic potential of the H5N1 and H1N1 strains of influenza because of developing drug resistance and human-to-human transmission. In the current study, the docking of fragments derived from FDA approved drugs followed by fragment linking within the neuraminidase (N1) enzymatic pocket is used to create a library of potential inhibitors for virtual screening. Though virtual screening is a well-established technique, it does not typically account for the entire range of receptor flexibility. The Relaxed Complex Scheme (RCS) partially resolves this problem by integrating data from molecular dynamics simulations with computer docking. Many of the novel molecules generated here scored better than known neuraminidase inhibitors like oseltamivir, peramivir, and zanamivir.
POSTER #4:
Dendritic cell expressed LIGHT and BTLA modulate T cell IL2 receptor and IL2 Secretion
Lisa Geary
Dr. Carl Ware
Herpesvirus entry mediator (HVEM) is a TNF (tumor necrosis factor) superfamily member shown to affect T cell responses. HVEM binds four known cellular ligands, the TNF family members LIGHT and lymphotoxin‐α (LTα) and the immunoglobin superfamily members BTLA (B and T lymphocyte attenuator) and CD160. The mechanism of how HVEM influences T cell activation is not understood. In this study, we show that the HVEM ligands LIGHT and BTLA have critical, yet reciprocal, roles in CD4 T cell activation by affecting expression of the α‐chain of the receptor for IL2 (IL2Rα) and IL2 secretion, a critical growth factor for T cells. These findings suggest a mechanism for the role of LIGHT and BTLA in T cell‐mediated immune responses.
POSTER #5:
Unrecognized Diastolic Dysfunction and Its Contribution to Heart Failure
Ashwani Gore
Dr. Ronald Dueck
We performed a small retrospective cohort study examining the clinical features and outcomes of surgical patients with documented evidence of left ventricular dysfunction compared to those with no echocardiographic abnormalities. Our study revealed a significant number of patients with LV dysfunction were found to have clinical findings consistent with heart failure during surgery and within a few days of their procedure. We found that both groups with evidence of LV dysfunction demonstrated an increase in the risk of decompensating to heart failure and that those with diastolic abnormalities were slightly more at risk than those with systolic abnormalities. Patients with preserved ejection fractions were more prevalent in the population studied compared to control subjects and those with ejection fractions less than fifty percent. This is evidence that diastolic dysfunction and its contribution to heart failure may not only be under recognized in the community but could also constitute a significant modifiable risk factor for surgical patients undergoing general anesthesia. Upon review of echocardiographic reports we found that many patients had abnormal indices of LV diastolic function yet were categorized as normal proving that the diagnosis is difficult even by experienced clinicians.
POSTER #6:
The Identification of Conserved Enhancer Regions from the msh gene in Drosophila Melanogaster
Michael Harabaglia
Dr. Ethan Bier
In genetics, an enhancer represents a short region of DNA that can bind activator proteins. Binding in this region can initiate the transcription of a nearby gene or one on a separate chromosome. This increase in transcription is due to the activators recruiting transcription factors, which enhances the binding of RNA polymerase. The main objective is to use a bioinformatic approach to determine the conserved enhancer region in the msh gene which is involved in the patterning of the nueroectoderm in flies. This information can then be utilized to provide a reliable and testable prediction of the conserved mechanism for patterning the ectoderm. These results are able to be used to determine the level of enhancer conservation from Drosophila Melanogaster to the beetle, bee, mosquito, and eventually to the zebra fish vertebrate. The methodology is comprised entirely of bioinformatics tools including both unpublished programs and those published such as ClustalW and BigFoot. As of now, significant conservation has been found throughout the Drosophila genomes and modifications are being made to identify highly significant hits in the organisms mentioned above. It is hypothesized however that the mechanism for neuroectoderm patterning is highly conserved and therefore patterns with high significance will be found in the beetle, bee, mosquito, and zebra fish genomes. These results would imply that that the sensitivity of the msh gene to BMP signaling in vertebrates has the same mechanism as that in Drosophila Melanogaster and does not follow the inverted mechanism currently accepted in academia.
POSTER #7:
Using an LCMV fusion peptide as a model antigen system
Elisabeth Krow-Lucal
Dr. Shane Crotty and Dr. Ananda Goldrath
Germinal centers are essential for the generation of long-term immunity due to their role in the differentiation of long-lived plasma cells and memory B cells. Because nearly all vaccines are protein based, it is important to understand germinal center formation and regulation induced by individual protein antigens within the broader context of an infection. In order to study the immune response to a protein antigen, many groups have used the ovalbumin (OVA) model antigen system. Because OVA is not expressed by any pathogen, an anti-OVA immune response tends to be very weak and not comparable to the immune response against a typical infection. Consequently, the OVA system is not ideal for the study of vaccine development. To develop a more physiologically relevant system, we fused the LCMV gp61 minimal CD4 T cell epitope (amino acids 66-77) with the gp2 protein that is recognized by B cells. The resulting fusion peptide enables LCMV gp1-specific CD4 T cells such as SMARTA TCR transgenic cells to provide antigen-specific help to gp2-specific B cells. We have shown that this peptide can be used to study the germinal center reaction using far lower and more physiological concentrations of antigen and antigen-specific CD4 T cells than are used in the OVA system.
POSTER #8:
Both Protein Kinase A and Epac (Exchange protein directly activated by cAMP) decrease pulmonary artery smooth muscle proliferation: Decreased Epac expression and activity is associated with Pulmonary Arterial Hypertension.
Ohmin Kwon
Dr. Paul Insel
Decreased levels of the second messenger 3’5’-cyclic adenosine monophosphate (cAMP) contribute to pulmonary vasoconstriction, vascular proliferation and remodeling of the pulmonary artery that is associated with pulmonary arterial hypertension (PAH). The actions of cAMP are largely mediated by protein kinase A (PKA) and exchange protein activated by cAMP (Epac). Using pulmonary artery smooth muscle cells (PASMC) isolated from patients with PAH and an animal model for PAH [the monocrotaline-treated (MCT) rat], we investigated the expression and function of these two mediators of cAMP-signaling. Activation of both PKA [by N6- Phenyladenosine-cAMP, (N6), 50 μM, 24 hr] and Epac [by 8-pCPT-2Me-cAMP, (8Me), 50 μM, 24 hr] inhibited the proliferation of control-PASMC. Both inhibition of PKA [by Protein Kinase Inhibitor, (PKI), 5μM, 24hr] and the downstream mediator of Epac, Rap-1 [by GGTI-298, 1μM, 24hr] stimulated the proliferation of control-PASMC. In PAH-PASMC the anti-proliferative effect of 8Me, but not N6, was blunted and corresponded to a decrease in the mRNA and protein expression of Epac-1 and Epac-2 and reduced Rap-1 activation (50 μM, 15 min). Consistent with those findings, lung homogenates from MCT-treated rats had a prominent decrease in Epac-1 RNA and protein expression and Rap-1 activity. These results indicate that the activation of both PKA and Epac inhibit the proliferation of PASMC and that PAH is associated with a decrease in Epac expression and activity. Moreover, the findings imply that normalization of Epac dependent-signaling may be useful for the treatment of PAH by enhancing the beneficial effects of drugs that act via increasing cAMP.
POSTER #9
Effects of an inactivation of the hippocampus on the retrieval of spatial information and on the acquisition of new spatial information in a 6-arms radial maze with minimized navigational demands
Ashley Linder
Dr. Stefan Leutgeb
It is widely believed that the hippocampus plays an essential role in the acquisition of spatial information. This is seen in tasks that require the rats to learn the location of a relevant place. The hippocampus is also important in the retrieval of declarative memories acquired in a recent past. With time, the memories become progressively independent of the hippocampus and are finally stored in the neocortex. However, most studies with spatial memory tasks reported that rats with hippocampus lesions were impaired in the retrieval of both recent and remote spatial information. This deficit might reflect an impairment in hippocampus-dependent navigational processes crucial for the expression of the spatial memory rather than an impairment in the retrieval of spatial information. The goal of this study was two fold. First, we investigated the involvement of the hippocampus in the retrieval of a spatial information acquired in a 6-arms radial maze with minimized navigational demands. Second, we studied the involvement of the hippocampus in the learning of new spatial memory information in well-trained rats in the 6-arms radial maze. Male Long Evans rats were implanted with 4 guide cannulas targeted bilaterally to the dorsal and the ventral hippocampus. A micro infusion of muscimol, a selective GABAA agonist, enabled us to inactivate the hippocampus at precise moments during the task. All rats were trained over 20 days to locate an invariant baited arm. A single retention test was given 24 hours after the last training day. Under muscimol, the retrieval of the position of the baited arm was mildly impaired in comparison to the retrieval under PBS. All rats were then trained over 5 days in a similar task in another room. They were subjected to micro infusions of PBS or muscimol before the acquisition. Our results showed an anterograde memory deficit in the muscimol rats. The rats were then trained in the familiar room on a reversal task. They had to learn the location of a new goal arm. Rats under muscimol were impaired in the learning of the new goal arm location but they showed a significant retrieval for the old goal arm location. Our results show that an inactivation of the hippocampus leads to a strong anterograde memory deficit while the retrograde deficit is much weaker. This pattern of results reflect the deficits seen in humans with hippocampal lesions.
POSTER # 10
The Role of Sox9 as a Marker for Multipotential Behavior in Developmental Pancreas
Jenny Ma
Dr. Maike Sander
The adult pancreas is comprised of three main cell types: acinar (exocrine), islet (endocrine), and ductal cells. These cells arise through a process of neogenesis from the early pancreatic progenitors that begin to bud from the endoderm at e8.5. Previous expression studies demonstrate that these cells are positive for Pdx1 expression. Lineage analysis of these cells by using Pdx1 regulatory regions to drive the expression of an inducible Cre recombinase resulted in the activation of cre-dependent reporter alleles within the Pdx1 positive cells and all their progeny. These experiments demonstrated that Pdx1+ cells are capable of making all three cell types of the pancreas. However, this potential is lost as development progresses and Pdx1 becomes restricted to differentiated endocrine cells. Recently, our laboratory has identified Sox9 as a marker of the progenitor domain and developed a Sox9 promoter driven CreER to analyze the potential of Sox9+ cells throughout development and adulthood. With the injection of tamoxifen into mice, the CreER gene becomes active in SOX9+ cells. The cre/loxP sites within the reporter allele then undergoes recombination and cleaves the stop cassette, initiating expression of the enzyme B-geo. Thus, recombination events result in a stable and heritable expression of B-geo which can be visualized by Xgal staining. We have analyzed embryonic and postnatal ages and shown that these cells remain multipotential at least until ten days after birth. Current studies are ongoing to quantify the relative ability of Sox9+ cells to produce all three cell types at different times during development. Furthermore, we are examining when and if this potential is lost with age as this cell type would be very valuable during normal growth and injury-induced regenerative events.
POSTER # 11:
Sox9 as a Marker for Multipotent Pancreatic Progenitors
Joey Nguyen
Dr. Maike Sander
Three specialized cell types exist within the pancreas, the endocrine, exocrine, and ductal cells. Although these cells are different in type and function, previous studies have shown all cells type can originate from early progenitor cells, indicating that these early progenitors are multipotent. Many studies have demonstrated that the transcription factor Pdx1 is a marker of these early multipotent progenitors. However, expression of Pdx1 becomes progressively restricted to endocrine cells as pancreatic development progresses. Therefore, the existence of possible multipotent cells after Pdx1 expression becomes restricted is unknown. Research from our laboratory recently identified another transcription factor as a marker for multipotent progenitors. Our laboratory demonstrated through short-term lineage analysis that cells marked by Sox9 expression are multipotential through embryonic stages as late of E15.5. To more thoroughly test our hypothesis that Sox9+ cells retain multipotency up to E15.5 and possibly longer, we utilized the mouse line, Sox9-CreER, which enables us to temporally and permanently mark progenitor cells and their progeny at different embryonic stages. To test whether an individual Sox9+ cell is capable of creating all three pancreatic cell types, I utilized a low level activation of the Sox9creER transgene to label only a few cells within the pancreas at different times throughout pancreatic development. The pancreata of injected mice were harvested at 21 days after birth and analyzed to identify the progeny of these few labeled cells. These experiments will allow me to more rigorously determine whether an individual cell exists within the pancreas that maintains a multipotent status throughout the development of the pancreas. These studies, as well as other studies on going in the laboratory, are establishing the Sox9 transcription factor as a marker of multipotent pancreatic progenitors into the post-natal stage. This suggests Sox9+ cells may also contribute to regenerative events within the adult pancreas. Overall these discoveries will allow us to further analyze how micro-environmental factors influence the developmental potential of individual Sox9+ cells.
POSTER # 12:
The role of the headcase gene in regulating stem cell behavior in the Drosophila testis
Darrell Tran
Dr. Leanne Jones
Stem cells have the unique ability to divide asymmetrically to generate another stem cell (self-renew), while also giving rise to a differentiated line of daughter cells. The ability to maintain the stem cell population and the continued production of differentiated progeny allows for the maintenance of tissues that must be constantly replenished throughout the lifetime of an individual. The processes through which the identity and function of stem cells is maintained are still unclear; however, it is clear that the local microenvironment (niche) plays a key role in regulating stem cell behavior. This study attempts to characterize the role of the gene headcase (hdc) within the germline stem cell niche in the Drosophila testis. The process of spermatogenesis in Drosophila provides a well-characterized, genetically tractable system for exploring stem cell regulation. Fluorescent markers targeting stem cells and other components of the “niche” allow for the study of stem cell behavior in vivo. We have demonstrated that hdc is expressed in both somatic and germline cells in the testis. Furthermore, our results suggest that hdc is necessary for proper functioning of “hub” cells, a cluster of post-mitotic somatic cells that are key to the stem cell niche in the testis. Future experiments are aimed at determining whether hdc interacts with pathways known to be important for maintaining the function of the niche and consequently regulating stem cell behavior, particularly with the JAK/STAT signalling pathway or via the transcription factor, escargot (esg).