Author(s): Alyssa Sanchez Biology Macie Davis Biology Olivia Earley Biology Alex Mercer Biology Ava Monroe Biology Itzel Perez Orozco Biology
Advisor(s): Magnus Rittby Biology
Location: Session: 2; 2nd Floor; Table Number: 3
We will be attempting to answer the question: What is the effect of microgravity vs gravity on the growth of a lentil bean? We chose this test subject to determine if lentil beans are a solution to help bone density issues and bone degeneration while astronauts are onboard the International Space Station.
While astronauts are in space, their bones degenerate and they lose muscle tone. Lentil beans can help bones and muscles develop as they contain calcium, magnesium, potassium, and protein. In our experiment, we hope to learn the effects of microgravity on plant growth ans to see if lentils grow the same in both environments. We can also use the information gathered from the lentils to conclude whether or not microgravity conditions are an adequate environment for farming and developing crops, which in turn will help determine if lentils are an appropriate crop to cultivate while on board the ISS.
Lentil beans are part of the legume family, which are usually inexpensive, nutritionally dense and a great source of protein. They are also a good source of calcium, magnesium, and potassium. Besides human consumption, lentil beans can be used for livestock feed too. In the agricultural context, the lentil beans can be utilized as a rotational crop with wheat. Lentil beans are a highly nutritious food, rich in minerals, protein, and fiber. Lentil beans are an economical source of protein, meaning it is affordable at a low-cost to prepare the beans. Lentil beans can be used as a supplement to a grain diet due to the high-protein and high-carbohydrate nutritional content.
Our hypothesis is that lentil beans will grow faster in space since there is a lesser amount of gravity in the ISS. Our experiment will help us understand how to better provide a sustainable food source for astronauts. Lentil beans, along with exercising, will allow their bones and muscles to stay strong and healthy in a microgravity environment. With our collected data after the experiment, the science community will understand how the effects of microgravity have on the growth of the lentil bean. If we explore and further understand the growth effects in microgravity of a lentil bean, this will allow us to seek deeper into understanding how other useful plants will grow in microgravity. This study will add to the research that has already been conducted. This experimental test is crucial to analyze the adjustments or changes that might need to occur to continue the legacy of the lentil bean in microgravity.
(Poster is private)
Indigo Buntings (Passerina cyanea) and Painted Buntings (Passerina ciris) are closely related songbirds in the family Cardinalidae, found to co-exist in areas where ranges overlap. However, though both species share similarities in morphology, diet and preferred habitat characteristics, there is little quantitative data accumulated about the Painted Bunting and many aspects of its life history remain unclear. North American Breeding Bird Surveys have shown a significant decline in Painted Bunting population numbers across their ranges—a decline that has resulted in its designation of a Species of Special Concern by Partners in Flight. Proposed reasons for the decline include habitat destruction, sensitivity to disturbance and factors associated with decreased success in breeding. Within the Great Trinity Forest, the Indigo and Painted bunting’s breeding grounds overlap. The Great Trinity Forest is a large urban forest surrounded by the city limits of Dallas, TX containing a variety of disturbance factors characteristically associated with a highly urbanized area: poor habitat, invasive species, and increased noise and light. Sensitive species, such as the Painted Bunting, are typically found to avoid areas of disturbance. Data collected May-July 2018 shows presence/absence of both species within 140, 5 ha plots spanning the forest. Additional disturbance data was collected, including noise levels (db), invasive wild hog activity and percent impervious surface both within and surrounding each study site. Analysis of this data will aid in discovering how these species distribute themselves in relation to disturbance factors, urbanization and each other. Results will further serve to assist in future conservation efforts and increased life history knowledge of the painted bunting. It is predicted that disturbance factors within the Great Trinity Forest have a significant effect on Painted Bunting presence/absence while they have no significant effect on the Indigo Bunting.
Large numbers of bats are killed at wind energy facilities world-wide and there is a pressing need to improve our understanding of why this is happening and develop effective strategies to minimize impacts. Although Texas has more installed wind energy than any other state in the U.S., there are very few publicly available data about bat mortality at Texas wind farms. This is especially true of areas that are only recently seeing wind energy development, such as far south Texas in the Rio Grande River Valley. A couple of reports suggest that northern yellow bats (Lasiurus intermedius) and southern yellow bats (Lasiurus ega) may frequently be killed at these wind energy facilities, but we know very little about population sex ratios or population structure in these two species. In collaboration with a researcher at Texas State University, San Marcos, we have extracted DNA from tissue samples taken from 88 northern yellow bats and 64 southern yellow bats killed at wind farms in Starr and Hidalgo Counties. First, we used a genetic method, in which we amplified regions of the X and Y chromosomes using PCR, to determine the sex of the bat carcasses. Next, we used a DNA barcoding approach to assess the accuracy of species identification in the field. These efforts represent the first steps in a study to evaluate genetic diversity and population structure in two species of yellow bats that will likely be negatively impacted by wind energy development.
(Poster is private)
Methylmercury (MeHg) is an environmental contaminate that has harmful effects on
wildlife. Anthropogenic sources like coal mining emit inorganic mercury (Hg) into the
atmosphere. From the atmosphere, Hg is deposited into aquatic ecosystems. Once in aquatic
ecosystems, inorganic Hg is converted to MeHg by bacteria and enters the food web. Emergent
aquatic insects (e.g. dragonflies), insects with aquatic larval stages and terrestrial adult stages,
will transport MeHg from the aquatic ecosystem to terrestrial predators like songbirds.
This project focuses on MeHg contamination of nestling Red-winged blackbirds
(Agelaius phoeniceus) from nests at the Eagle Mountain Hatchery Pond Facility. It is believed
that nestling Red-winged blackbirds (RWBL) consume aquatic-based prey, primarily odonates
(damselflies and dragonflies) but can consume terrestrial prey as well. Odonates are known to
have high levels of MeHg contamination. Although studies have attempted to observe what
RWBL parents feed nestlings, there are no studies of the actual prey composition in the
nestlings’ digestive tracts. Insects consumed by birds can be analyzed because external coverings
of insect body parts (head capsules, mandibles, legs) are composed of undigestible chiton. This study looks at nestling RWBL diets to quantify odonates in their diets. We will sort through varying fecal samples from the Pond Facility in order to determine the diet composition of the RWBL, and if the composition correlates with MeHg levels in nestlings.
All aquatic systems are contaminated with mercury (Hg) from atmospheric deposition. In aquatic systems, Hg is converted to toxic methyl mercury (MeHg). Methyl mercury enters the base of the food chain and biomagnifies as it moves up to top trophic level consumers such as fish. Most research on MeHg in fish has focused on their risk to human health. Although lab studies have suggested that MeHg also poses a risk to the health of the fish, there have been few field studies that examine the risk of MeHg to fish. Because game fish are the basis of a multi-billion dollar fishing industry, it is important to understand the potential effects of MeHg on the health of game fish. The objective of my study is to determine if MeHg concentrations of game fish in the Southeastern U.S. surpass known risk thresholds for mercury effects on fish health. I will be evaluating concentrations of MeHg in two popular game fish species; largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus). Largemouth bass and bluegill are high and low trophic position fish, respectively. I will use data from the USGS National Fish Database and a statistical model developed by Wente et al. 2004, to predict MeHg concentrations in five lengths for each fish species. Then using a GIS based Spatial Analysis, I will assess the effects of mercury deposition, fish trophic position and fish length on MeHg concentrations and whether MeHg concentrations pose a risk to game fish health in the Southeastern U.S.
In many patients with breast cancer, a mutation in their BRCA1 gene disrupts BRCA1 protein’s function as a tumor suppressor. One mechanism through which BRCA1 prevents cancer is by acting as an enzyme to attach a signaling protein called ubiquitin to a H2A, a DNA packaging protein. This attachment inhibits gene expression of DNA damaging proteins. Here, we determine whether enzymatic activity of BRCA1 towards H2A is a conserved feature in C. elegans, a microscopic worm used as a model organism.
To measure conservation, we used mutagenesis to introduce mutations into C. elegans’ BRCA1 at a region homologous to the known human H2A binding site. Similar to mutations at this site in human BRCA1, our results showed a decrease in enzymatic activity when mutations were present. This indicates that C. elegans BRCA1 and human BRCA1 use similar mechanisms of attachment to H2A. To develop tools to study this reaction in C. elegans, we need to understand the position on H2A to which ubiquitin is attached. To accomplish this, we generated C. elegans H2A using cloning to eventually determine the specific location of ubiquitin attachment.
Our experiment is about diabetes and Human and synthetic insulin crystallization in a microgravity environment. This experiment is designed to help us find out if there is a way to prevent crystallization of insulin, especially if we understand how it happens in microgravity. When insulin crystallizes, the bacteria that usually makes it viable stops working. This would cause it to be ineffective for patients in dire need of this medication. To complete this experiment we would like to send three different varieties of insulin in a type 3 mini lab FME (Fluids Mixture Enclosure) to the International Space Station (ISS), kept in ambient temperatures, to see if it crystallization occurs within a certain amount of time. We will keep the experiment refrigerated at or below 40℉ during transportation to the ISS and again after arrival back to our lab to prevent crystallization occurring outside of the experiment. Refrigeration slows the crystallization growth and this is how it is stored on Earth. Keeping our experiment refrigerated during transportation is an important step because the insulin crystallization growth should only be measured while in microgravity. It is also important to note that crystallization of insulin is slow so change in crystal growth will not be evident if out of refrigeration for short periods of time. We would like to keep our insulin types out of refrigeration for a period of six weeks minimum. While testing insulin crystallization in microgravity, we will be conducting the same experiment on Earth as our control. If we can understand more about synthetic insulin, maybe one day diabetic men and women can follow their passion of being astronauts and humans with this disease will have the opportunity to go to microgravity environments for extended periods of time.
(Poster is private)
Hepatitis C virus currently infects around 130-170 million people. HCV, a member of the Flaviviridae family, causes chronic liver inflammation which can lead to liver cirrhosis or hepatocellular carcinoma. One of the nonstructural proteins of HCV, NS5A, is known to diminish the host innate immune response via inhibition of antiviral gene expression. NS5A blocks NFkB from entering the nucleus, decreasing transcription of IFN-B. Specifically, NS5A 10A, a mutant form of the protein, is known to greatly diminish the activity of the IFN B promoter. Our goal is to determine how WT NS5A and another mutant, NS5A H27, affect this pathway as well. We did this by transfecting HEK 293 cells with the NS5A mutant of interest, infecting the cells with Sendai virus, and subsequently measuring the activity of the IFN B promoter using a luciferase assay. In addition, NS5A contains three domains: I, II, and III. We are interested in determining which domain of NS5A is particularly important for blocking antiviral gene expression. We designed primers to created truncations of the protein containing the individual domains via PCR.
Author(s): Thomas Thalhuber Biology Matthew Chumchal Biology Ray Drenner Biology William Zudock Biology
Advisor(s): Matthew Chumchal Biology Ray Drenner Biology
Location: Session: 2; 2nd Floor; Table Number: 7
(Poster is private)
Red-winged blackbirds (Agelaius phoeniceus) are found throughout North America, often nesting in cattails in ponds and wetlands. Diet studies have revealed that adults can feed their nestlings both emergent aquatic insects like odonates and terrestrial insects like lepidopteran larvae. Because emergent aquatic insects can be contaminated with high amounts of methyl mercury (MeHg), it has been hypothesized that nestlings fed high amount of odonates would be contaminated with levels of MeHg that are hazardous to their health. There have been no of studies of MeHg contamination of nestling Red-winged blackbirds and their diet. The objective of our study was to measure the concentration of MeHg in blood of nestling Red-winged blackbird and to estimate the proportion of emergent aquatic insects and terrestrial insects in their diet. We conducted a study of Red-winged blackbird nestlings at 20 ponds at the Eagle Mountain Fish Hatchery, Fort Worth, Texas. The ponds are contaminated with Hg from the atmosphere. Previous studies at the Hatchery have demonstrated that emergent aquatic insects such as odonates have high concentrations of MeHg while terrestrial insects on the pond shorelines have low concentrations of MeHg. Red-winged blackbirds nested in cattails in the ponds from April 9 to July 30 2017. We collected 424 blood samples from 243 nestlings from 88 nests (1-2 samples from 1-4 nestlings per nest). We analyzed the blood for MeHg, and analyzed 202 of the blood samples (1-2 blood samples from 1 per nest) for nitrogen stable isotopes. Methyl mercury was detected in nestling blood suggesting that Red-winged blackbird nestlings were fed emergent aquatic insects. However, concentrations of MeHg in nestling blood were low (mean of 0.020 ug/g ww) and below the risk threshold. Methyl mercury concentrations and nitrogen stable isotope ratios for Red-winged blackbird nestlings suggest that terrestrial insects composed a high proportion of their diets. Our study suggests that Red-winged blackbird nestlings may not be at risk of MeHg contamination when terrestrial organisms dominate their diet.
(Poster is private)
Previous studies showed that exposures to thyroid inhibitors during early stages of development lead to long-lasting alterations in disease resistance. Therefore, the goal of this project was to assess the effects of early life stages thyroid disruption on the maturation and function of immune cells using propylthiouracil (PTU)-exposed fathead minnow as a model system. The specific objectives of this study were to evaluate the impacts of early life stage PTU-exposure on 1) neutrophil migration and 2) transcriptomic markers of lymphoid and myeloid cell development. These objectives were accomplished by exposing fathead minnow embryos to 35 mg/L and 70 mg/L PTU for 10 days, while evaluating neutrophils migration with a tail nicking assay and assessing immune cell development by measuring transcriptomic markers of maturation at 10 days post fertilization (dpf). There were no differences in transcriptomic markers for lymphoid cell development between PTU and control groups. However, PTU-exposed larvae showed a decreased amount of neutrophils at wound site as well as decreased v-ymb expression compared to those of the control at days 7 and 10, indicating that early life stage thyroid disruption interfered with the normal development and subsequently reduced immune response in these organisms.
Purpose: The objective of this retrospective study was to identify genetic variants of gene encoding a major drug-metabolizing enzyme among two different races – African American and Caucasian – based on pharmacogenomics testing and interpretive report (GeneSight). The study might shed lights for the application of precision prescribing in the clinical settings in the near future.
Methods: A retrospective study of de-identified interpretive reports from GeneSight of sixteen individuals (n = 16) at the Mental health Mental Retardation (MHMR) of Tarrant County. There are five reports of male and eleven reports of female in this study, of which six are African American and ten are Caucasians. The study was divided into two groups based on their races. Percentage of different alleles within variants of the CYP gene family were determined. Based on genetic components of patients, drug recommendations were made by AsureRx Healh, Inc.
Hypotheses: CYP2 is known to be highly polymorphic in the scientific literature. It is hypothesized that genetic variants will be observed in the CYP2 gene.
Cancer is one of the leading causes of death in the United States and is predicted to directly affect 38% of the population over the course of their life. Cancer is categorized as a collection of diseases primarily characterized by aberrant cellular proliferation. Many current cancer therapies, such as chemotherapy, do not differentiate between cancer cells and normal cells resulting in a variety of negative side effects. In an attempt to minimize these side effects, there has been a huge impetus to develop targeted therapies, which exploit cancer-specific molecules to exhibit selective toxicity towards cancer cells. For example, the monoclonal antibody Trastuzumab (Herceptin) targets the Human Epidermal Growth Factor Receptor 2 (HER2) that is overexpressed in some breast cancer cells. Another cancer-specific molecule overexpressed in some breast cancers, as well as cervical cancers, is the receptor for biotin. Biotin, more commonly known as Vitamin B7, functions intracellularly as an important coenzyme for several carboxylase enzymes involved in fatty acid synthesis, amino acid metabolism and gluconeogenesis. Thus, by overexpressing the biotin receptor some cancers increase their overall absorption of biotin resulting in a higher metabolic and proliferation rate. Furthermore, the high metabolic rate in cancer leads these cells to have increased to damage by reactive oxygen species (ROS) which can trigger apoptosis at high intracellular levels. Therefore, our project is exploring this overexpression of the biotin receptor as a potential avenue for targeted therapy against certain breast cancers. Ferrocene is an organometallic compound with an iron-center that has been shown to generate ROS in cancer cells. Since certain breast cancers overexpress the biotin receptor and absorb biotin with a higher efficiency, we hypothesize that conjugating biotin to ferrocene will increase the efficiency of ferrocene entering cancer cells, resulting in selective toxicity. Therefore, we have produced a library of biotin-ferrocene conjugates to test their ability to selectively enter cancer cells and generate ROS. Experiments were conducted utilizing ferrocene and a variety of conjugates (C1, C2, C3, 2) in both cancer (MCF-7) and non-cancer cells (HEK293).
(Poster is private)
Endocrine disrupting compounds (EDCs) interfere with hormone production and action. EDCs typically mimic native hormones and often have a similar structure to natural hormones. While previous animal studies suggest that nitrate alters the synthesis of testosterone, nitrate is different than typical EDCs as its structure is not similar to that of any naturally occurring hormones. Given this and the environmental prevalence of nitrate, the objectives of this study are to 1) determine if nitrate acts as an EDC and 2) to better understand the mechanisms and effects of nitrate exposures on hormone production and reproduction. To achieve these objectives, groups of sexually mature adult fathead minnows were exposed to nitrate for 28 days. On days 7 and 28 of the exposure period, minnows were sacrificed for the collection of blood and gonads. The blood was used to evaluate hormone levels, while the gonads were used for gene expression analysis. Additionally, during the exposure, endpoints indicative of reproductive capabilities were also evaluated. There were no significant differences between exposure groups regarding gene expression, and there were no dose-dependent differences in egg production over the course of the breeding study.
(Poster is private)
Floral herbivory (florivory) can have direct effects on both female and male reproductive output. Damage to flower parts such as petals and anthers can also have potential indirect effects by altering floral attractiveness to pollinators. Because carnivorous plants live in nutrient-poor environments and have slow growth rates, these plants may be at increased risk of negative effects of florivory. However, there has been no study to investigate florivory in carnivorous plants. We conducted a two-year field study on an east-central Texas population of the carnivorous pitcher plant Sarracenia alata and its specialist herbivore Exyra semicrocea. Populations were surveyed for number of flowers attacked, and the mass of floral components was compared between attacked and unattacked flowers. In 2017, a mean of 65% of flowers were attacked at the end of the flowering season. Based on mass before dehiscence, the mass of anthers after florivory was 49.5% of unattacked anthers. There were no significant differences in the masses of other floral structures at the end of the season. In 2018, 38% of flowers surveyed were attacked. The mass of attacked ovaries was 47% that of unattacked, the mass of sepals and petals combined was 62.5% that of unattacked, and the stigma/style complex was 51.0% that of unattacked. The mass of attacked anthers before dehiscence was 18.7% that of unattacked anthers. This study shows that there was annual variation in both the proportion of flowers attacked in the population, and the extent of damage seen in floral structures. Future studies should examine the effects of florivory on pollen limitation, pollinator behavior, and recruitment in Sarracenia alata.
It is extremely important in our age to look for alternative, more environmentally favorable energy sources. The Sun is a largely unused and widely available energy source to power human industry which can be utilized in different ways. Photovoltaic cells directly convert solar energy to electricity but only provide power when illuminated. Supplying solar-sourced energy during night hours and inclement weather requires conversion to another form, for instance into chemical fuel by means of water splitting into oxygen and hydrogen. This strategy, inspired by natural photosynthesis, is currently a promising and actively researched approach. However, achieving a high energy conversion efficiency, which is essential for industrial implantation of the method, remains a primary goal.
A Dye-Sensitized Photoelectrochemical Solar Cell (DSPEC) is specifically designed for using solar energy to generate hydrogen from water. We are pursuing the formation of photoanodes with polymer surface coatings prepared by electropolymerization. The polymer interfaces are designed to promote directional electron transfer at the interface, thereby resulting in a better solar energy conversion efficiency. The structure of the surface polymer enables the incorporation of catalyst units to the interface. To this end, we have prepared several novel iridium-oxide nanoparticle suspensions, using two different synthetic methods, to serve as the water-oxidation catalysts in our system. During the synthesis, the nanoparticles are functionalized with specific capping groups that contain terminal double bonds, through which they can be incorporated to the surface polymer electrochemically. Using acrylic acid and acrylamide as small molecule precursors, electro-polymer coatings have been prepared on FTO (fluorine-doped tin oxide) surfaces. Future research work will involve the incorporation of functionalized iridium oxide nanoparticles in the poly(acrylic acid/acrylamide) films and the characterization of their catalytic activity toward water oxidation. The method will then be extended to tin-oxide and titanium-dioxide semiconductor electrodes for preparing photo-active interfaces.
Ion solvation is fundamental in biochemistry. It controls the biophysical processes of protein solubility, reactivity, phase separation, crystallization and informational equilibria involving proteins and polypeptides. Ion solvation depends on the solute-solvent interactions which are governed by the properties of solvent like polarity, hydrogen bonding and ability to donate or accept electrons. These properties are subject to Pearson’s hard–soft acid–base (HSAB) effect and are characterized as hardness and softness of solvents. There have been attempts to connect the solvent hardness-softness to molecular properties and some empirical scales have been devised like μ-scale, DS scale and difference between the IR wavenumber shift of the C-I stretch of ICN and the O-H stretch of phenol. Only limited attempts have been reported to correlate the properties of solvents obtained from quantum chemical calculation to these empirical scales of solvent hardness-softness.
Our new quantum chemical descriptor, Orbital Overlap Distance, D(r), measures the size of orbital lobes that best overlap with the wavefunction around an atom. Compact, chemically stable atoms in the molecule tend to have overlap distances smaller than chemically soft, unstable atoms. Plots of D(r) on computed molecular surfaces, like electron density or spin density, distinguishes and quantifies the chemically soft and hard regions of a molecule. We propose that D(r) can be considered in terms of HSAB theory in order to predict solvation of ions. Our initial studies exhibit that D(r) of many common solvents correlates well with Marcus’s empirical μ-scale of solvent softness. Our studies provide a direct method to estimate the softness-hardness of solvents by using standard quantum chemical calculations.
Author(s): Allison Buckingham Chemistry & Biochemistry Keira Clotfelter Chemistry & Biochemistry Jack Dietz Biology Tommy Gifford Chemistry & Biochemistry Waylan Kisor Chemistry & Biochemistry
Advisor(s): Magnus Rittby Chemistry & Biochemistry
Location: Session: 2; Basement; Table Number: 9
This is experiment is designed to test how Nylon 6-10 is constructed and responds in a microgravity environment. Nylon 6-10 is a very flexible fiber. It consists of two chemicals called polypropylene and sebacoyl chloride to make the nano-structure for Nylon 6-10. We have developed several of ideas on what will happen to Nylon 6-10 in micro-gravity. We think that it will change the molecular structure of the Nylon 6-10 in micro-gravity for the better or worse. The good variable is that Nylon 6-10 might change into a very flexible, durable substance for many different applications both on Earth and in space. One concern we have is that Nylon 6-10 might change the molecular structure to not form any fibers or it might not dry by absorbing air molecules.
We decided to use Nylon 6-10 because of its overall construction. The industrial process for Nylon 6-10 is stronger and more flexible than Nylon 6-6. It is basically liquid rope. It can be used for repairs and manufacturing. It is an industrial chemical. A variety of products are created using Nylon 6-10, toothbrushes, paint brushes and even your underwear. It is a very common product in many of different industries and is a very useful product. It behaves like nylon fiber for thread or can be used for manufacturing different tools such as epoxy or fiberglass. The industrial ideas are very extensive and there are many suppliers.
Author(s): Hannah Carey Chemistry & Biochemistry Jason Mars Chemistry & Biochemistry
Advisor(s): Eric Simanek Chemistry & Biochemistry
Location: Session: 1; 2nd Floor; Table Number: 5
(Poster is private)
Recent trends in drug discovery research are directed at targeting protein-protein interactions. Blocking these interactions could be an effective strategy for treatment. Here, the synthesis of a macrocycle, a large ring-shaped molecule that is the same size as many protein-protein interaction sites, is described. The synthesis relies on the preparation of two different, crescent-shaped molecules through short, multistep syntheses. When these two molecules are combined together and subjected to acid to reveal reactive groups, a spontaneous assembly process occurs. The macrocycle is characterized by conventional methods including 1H NMR (which reveals a diagnostic signal for cyclization), 13C NMR, and mass spectrometry.
Author(s): Marlius Castillo Chemistry & Biochemistry Zygmunt Gryczynski Physics & Astronomy Zhangatay Nukureyev Physics & Astronomy
Advisor(s): Sergei Dzyuba Chemistry & Biochemistry
Location: Session: 1; Basement; Table Number: 3
(Poster is private)
Soft matter, such as organogels, waxes and polymer films have found numerous applications in various areas of sciences, engineering and medicine. Ability to assess and monitor their structural organization and physical properties is of the outmost importance. However, there are no convenient methods to accomplish this task.
Small molecule environmental probes have been instrumental in providing information about changes of various types of media upon exposure to external stimuli. Our group has demonstrated the validity of using these probes, also known as molecular rotors, for investigating various types of media. This poster will highlight our efforts on the developments and applications of ratiometirc molecular rotors that allow determining structural integrity as well as properties of various industrially important, medically- and energy-relevant soft matter materials.
Pancratistatin is a natural alkaloid that can be isolated from the bulbs of Hymenocallis littoralis, which is a tropical plant commonly referred to as the Spider Lily. Pancratistatin has been shown to have potent cytotoxic anti-tumor activity in biological testing, meaning that it could be a key component for designing natural anti-cancer drugs. The key structural component responsible for the cytotoxic activity of Pancratistatin is the phenanthridone ring system. Pancratistatin has also been proven to combat RNA-containing flaviviruses such as Yellow Fever, Zika, and West Nile Virus. Previously reported procedures for synthesizing Pancratistatin have been reasonably successful, but they all involve the use of lengthy sequences that produce low yields in order to reach the desired product. The purpose of this research project is to provide a more efficient synthesis by increasing the final yield and decreasing the number of steps required. Through successfully synthesizing Pancratistatin, several different analogs of the molecule that contain the phenanthridone ring will also be obtained.
Author(s): Jackson Eber Chemistry & Biochemistry David Minter Chemistry & Biochemistry Adam Montoya Chemistry & Biochemistry
Advisor(s): David Minter Chemistry & Biochemistry
Location: Session: 1; 3rd Floor; Table Number: 3
Quinine is a naturally occurring alkaloid found in the bark of the cinchona tree.1 Its medicinal relevance cannot be overstated as it is one of the most widely used anti-malarial drugs in the world.1 While the synthetic pathway to derive quinine is of limited relevance due to its abundance and ease of extraction, the puzzle of engineering reactions to isolate a stereochemically pure product of quinine captivated chemists for generations. The purpose of this study was to prove the conceptual route proposed by Stotter, Friedman, and Minter2 for the stereochemically pure total synthesis of quinine via a non-nitrogenous analog where the two nitrogen atoms of quinine are substituted with carbon atoms. The product of the analogous route is 1,1’-Dideaza-Quinine. Quinine is stereochemically complex, containing four separate stereocenters, thus the synthesis of quinine opens up the possibility of generating sixteen different isomeric structures.3 While the total synthesis of quinine with the correct stereochemistry was accomplished in 2001,3 the proposed route simplifies the process by relying on a stereospecific aldol condensation to eliminate potential isomerization.2 The results of the study validate the proposed route and add to the field of Organic Synthesis by illustrating an example of a stereoselective aldol condensation. Additionally, due to the analogous nature of the synthetic route utilized, many novel compounds were generated adding to the body of knowledge available to the Chemistry community.
Liquid-liquid phase separation (LLPS) of protein aqueous mixtures is the reversible condensation of protein-rich micro droplets occurring below a well-defined LLPS temperature. LLPS studies of protein mixtures are fundamental for understanding the membrane-less compartmentalization inside living cells, protein-aggregation diseases, protein-based drug formulations, enzyme-based materials and molecular interactions. It is known that aqueous solutions of the protein lysozyme in the presence of phosphate buffer at neutral pH and physiological salt concentration undergo LLPS upon cooling below ≈ 0 °C. The obtained lysozyme-rich micro droplets rapidly dissolve upon heating above the LLPS temperature. In this work, it will be shown that an apparently undisruptive substitution of phosphate buffer with another well-known buffer, 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES), to lysozyme aqueous solutions significantly alter the LLPS mechanism. Specifically, contrary to the case of phosphate buffer, the micro droplets produced below ≈ 0 °C remain surprisingly stable upon heating even at ≈ 30-40 °C. Related LLPS studies in both acidic and basic conditions show similar anomalous LLPS behavior. Our results indicate that HEPES triggers a second protein self-assembly process that is catalyzed by LLPS. These findings show that protein aqueous mixtures in the presence of HEPES buffer could be exploited for the preparation of protein-based materials. They also suggest that the combination of a protein self-assembly with LLPS may be a mechanism involved in the formation of membrane-less globular compartments inside the cytoplasm of living cells.
Author(s): Nicholas Henderson Chemistry & Biochemistry Arshad Mehmood Chemistry & Biochemistry
Advisor(s): Benjamin Janesko Chemistry & Biochemistry
Location: Session: 2; Basement; Table Number: 5
Hard-soft acid base theory is often used to explain the selectivity of chemical reactions, under the assumption that hard (soft) nucleophiles prefer to react with hard (soft) electrophiles. Computationally, quantifying the relative hardness and softness of different sites in a molecule remains challenging. Our "orbital overlap distance function" allows us to quantify which regions in a molecule contain compact vs. diffuse molecular orbitals. Here we explore the idea that compact molecular orbitals correspond to chemically hard regions, and that diffuse and polarizable orbitals correspond to chemically soft regions. We combine the orbital overlap distance with electrostatic potentials to quantify the hardness and electrophilicity of different sites in heterocyclic aromatic compounds. Results are compared to known experimental trends in aromatic reactivity
(Poster is private)
The semiconductor Silicon (Si) remains a significant material in the electronic device and photovoltaic industries . Especially, nanostructured forms of Si with a porous morphology (pSi) exhibit interesting properties which can be controlled via modulating pore structure and surface chemistry . Recently, synthesis of a unique one-dimensional form of Si, namely nanotubes, with tunable structure (shell thickness, length, inner diameter and porous morphology) has been demonstrated, thereby suggesting newly emerging applications . For instance, recent works have indicated Si nanotubes (SiNTs) can efficiently serve as a reaction vessel for formation of organometal perovskite nanostructures and a template for superparamagnetic iron oxide (Fe3O4) loading , . In an observation of dissolution of SiNTs with a porous morphology (pSiNTs), the material readily resorbed in buffered media at physiological conditions in a similar manner to bioactive nanostructured porous silicon, thereby implying potential therapeutic applications of this material .
In chemotherapy, platinum-based cancer drugs, such as cisplatin and carboplatin, are widely used as effective drugs against various types of cancer . Interestingly, while elemental platinum nanoparticles (Pt NPs) have been well investigated in diverse catalytic processes, in recent years, Pt NPs have also been discovered as a potent anti-cancer agent in nanomedicine, implying the use of the nanodrug to counteract chemoresistance in some cancer cell lines , . Recent reports have also indicated that enhanced cytotoxicity against selected cancer cell lines is ascribed to ultra-small Pt NPs, especially those with size less than 3 nm . In this report, pSiNTs were investigated as a template for the formation of Pt NPs, and in vitro cytotoxicity of the composites was evaluated against HeLa cancer cells.
Regarding fabrication, pSiNTs with short lengths (~500 nm) and thin walls (~10 nm) were synthesized via a ZnO nanowire sacrificial template method. Based on a combination of characterization techniques [High resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray analysis (TEM-EDX)], it is suggested that pSiNTs surface functionalized with 3-aminopropyltriethoxysilane can facilitate formation of Pt nanocrystals (Pt NCs) with size ranging from 1-3 nm utilizing a K2PtCl4 precursor. By varying reaction conditions (concentration of Pt salt and incubation time), the amount of Pt NCs deposited on SiNTs can be sensitively tuned from 20 to 55 wt%. In terms of cytotoxicity evaluation of the composites against HeLa cells, cellular viability was assessed using CellTiter-Glo assays, which quantified the amount of ATP in metabolically active cells. Our findings suggest that Pt NCs-SiNTs composites were toxic to HeLa cells, and less than 50% cells were still viable after 3 days of treatment with the composites at doses of 35 μg/ml and 50 μg/ml. Results from caspase 3/7 assays also showed that caspase 3/7 level in cells treated with Pt NCs-SiNTs approximately ranged from 1.5 to 2-fold increase compared to cells without treatment, thereby suggesting apoptosis as the likely mechanism. In vitro cellular uptake studies analyzed by confocal microscopy also confirmed accumulation of the composites within the cytoplasm of the cells after the treatment, consistent with a “Trojan horse” mechanism in which high concentrations of Pt NCs are internalized within cells assisted by pSiNTs and subsequently released via dissolution of the nanotube matrix.
The studies presented herein describe a novel strategy to form and immobilize highly compact clusters of Pt NCs by using pSiNTs as a template. In terms of bio-relevant applications, in vitro studies provide new insights into the anti-cancer properties of the newly discovered composites in inducing apoptosis in HeLa cells, thereby providing significant potential uses of Pt NCs-SiNTs in cancer treatment. Further investigations into gene expression profile(s) may be necessary in order to clarify the impact of the composites on cell survival in terms of molecular mechanisms.
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The chemical hardness of a solvent can play a decisive role in solubility and reactivity in solution. Several empirical scales of solvent softness have been proposed. We explore whether computed properties of solvent molecules can reproduce these empirical scales. Our "orbital overlap distance" quantifying the size of orbitals at a molecule's surface effectively reproduces the Marcus μ-scale of solvent softness. The orbital overlap distance predicts that the surfaces of chemically hard solvent molecules is dominated by compact orbitals possessing a small orbital overlap distance. In contrast, the surface of chemically soft solvent molecules has a larger contribution from diffuse orbitals and a larger orbital overlap distance. Other "conceptual density functional theory" descriptors, including the global hardness and electronegativity, can also reproduce empirical solvent scales. We further introduce a "solvent versatility" RMSD Dsurf scale quantifying variations in the surface orbital overlap distance. "Good" solvents such as DMSO, which combine chemically "hard" and "soft" sites within a single molecule, possess a large RMSD Dsurf. We conclude by applying this approach to predict the Marcus μ-parameters for widely-used ionic liquids and ionic liquid - cosolvent systems.