BIOL2019THALHUBER31251 BIOL
Type: Graduate
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
(Presentation 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.
BIOL2019WINER58088 BIOL
Type: Graduate
Author(s):
Zane Winer
Biology
Advisor(s):
John Horner
Biology
Location: Session: 2; 3rd Floor; Table Number: 2
(Presentation 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.
CHEM2019BEERI11498 CHEM
Type: Graduate
Author(s):
Debora Beeri
Chemistry & Biochemistry
Advisor(s):
Benjamin Sherman
Chemistry & Biochemistry
Location: Session: 1; Basement; Table Number: 5
View PresentationIt 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.
CHEM2019CASTILLO16416 CHEM
Type: Graduate
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
(Presentation 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.
CHEM2019FAHIM64637 CHEM
Type: Graduate
Author(s):
Aisha Fahim
Chemistry & Biochemistry
Advisor(s):
Onofrio Annunziata
Chemistry & Biochemistry
Location: Session: 1; 3rd Floor; Table Number: 1
View PresentationLiquid-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.