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Exploring Flavonoid Glycosylation in Kudzu (Pueraria lobata)

The isoflavones in kudzu roots, especially the C-glycosylated isoflavone puerarin, have been linked to many health benefits. Puerarin contains a carbon-carbon glycosidic bond that can withstand hydrolysis. The C-glycosylation reaction in the biosynthesis of puerarin has not been thoroughly investigated, with conflicting reports suggesting that it could take place on daidzein, isoliquiritigenin, or 2,7,4ʹ-trihydroxyisoflavanone. Kudzu species were identified for use in comparative transcriptomics. A non-puerarin producing kudzu was identified as Pueraria phaseoloides and a puerarin producing kudzu was identified as Pueraria montana lobata. Through the use of the plant secondary product glycosyltransferase (PSPG) motif, glycosyltransferases (UGTs) were identified from the transcriptomes. The UGTs that had higher digital expression in P. m. lobata were examined further using additional tools to home in on the UGT that could be responsible for puerarin biosynthesis. One of the UGTs identified, UGT71T5, had previously been characterized from kudzu as a C-glycosyltransferase involved in puerarin biosynthesis through in vitro enzyme activity (with daidzein) and a gain of function approach in soybean hairy roots. Previous studies have not supported the end-product of a pathway such as daidzein as the target for C-glycosylation, and no genetic analysis of UGT function had been conducted in kudzu. The activity of …
Date: August 2021
Creator: Adolfo, Laci Michelle
System: The UNT Digital Library

Analysis of Multipartite Bacterial Genomes Using Alignment-Free and Alignment-Based Pipelines

In this work, we have performed comparative evolutionary analysis, functional genomics analysis, and machine learning analysis to identify the molecular factors that discriminate between multipartite and unipartite bacteria, with the goal to decipher taxon-specific factors and those that are prevalent across the taxa underlying the these traits. We assessed the roles of evolutionary mechanisms, namely, horizontal gene transfer and gene gain, in driving the divergence of bacteria with single and multiple chromosomes. In addition, we performed functional genomic analysis to garner support for our findings from comparative evolutionary analysis. We found genes such as those encoding conserved hypothetical protein DR_A0179 and hypothetical protein DR_A0109 in Deinococcus radiodurans R1, and Putative phage phi-C31 gp36 major capsid-like protein and hypothetical protein RSP_3729 in Rhodobacter sphaeroides 2.4.1, which are located on accessory chromosomes in both bacteria and were not found in the inferred ancestral sequences, and on the primary chromosomes, as well as were not found in their closest relatives with single chromosome within the same clade. These genes emphasize the important potential roles of the secondary chromosomes in helping multipartite bacteria to adapt to specialized environments or conditions. In addition, we applied machine learning algorithms to predict multipartite genomes based on gene …
Date: August 2021
Creator: Almalki, Fatemah
System: The UNT Digital Library

Effect of Phosphorus Starvation on Metabolism and Spatial Distribution of Phosphatidylcholine in Medicago truncatula Wild-Type and PDIL3 Genotypes

Symbiotic nitrogen (N) fixation (SNF) occurs in specialized organs called nodules after successful interactions between legume hosts and rhizobia. Within nodule cells, N-fixing rhizobia are surrounded by plant-derived symbiosome membranes, through which the exchange of nutrients and ammonium occurs between bacteria and the host legume. Phosphorus (P) is an essential macronutrient, and N2-fixing legumes have a higher requirement for P than legumes grown on mineral N. First, I investigated the impact of P deprivation on wild-type Medicago truncatula plants. My observations that plants had impaired SNF activity, reduced growth, and accumulated less phosphate in P-deficient tissues (leaves, roots and nodules) is consistent with those of similar previous studies. Galactolipids decreased with increase in phospholipids in all P-starved organs. Matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI-MSI) of phosphatidylcholine (PC) species in nodules showed that under low P environments distributions of some PC species changed, indicating that membrane lipid remodeling during P stress is not uniform across the nodule. Secondly, a metabolomics study was carried out to test the alterations in the metabolic profile of the nodules in P-stress. GC-MS based untargeted metabolomics showed increased levels of amino acids and sugars and decline in amounts of organic acids in P deprived nodules. Subsequently, …
Date: August 2021
Creator: Dokwal, Dhiraj
System: The UNT Digital Library
Sociality in Harris's Hawks Revisited: Patterns of Reproductive Output and Delayed Dispersal (open access)

Sociality in Harris's Hawks Revisited: Patterns of Reproductive Output and Delayed Dispersal

In the lower Rio Grande Valley of south Texas, more than half the nesting groups of Harris's hawks (Parabuteo unicinctus) include at least one auxiliary group member in addition to a breeding pair. To provide further insight into cooperatively breeding raptors, I evaluated sociality in Harris's hawks through the dual benefits framework. I explored the formation, structure, and stability of cooperative group formation across a spatially variable study area, which includes high levels of urbanization and development as well as remote, undisturbed native habitats with low anthropogenic impact. I used color banding, regular censuses of active territories, and a microsatellite relatedness analysis to examine patterns of sociality, including delayed dispersal, the effect of auxiliary group members on reproductive output, parentage of broods, and the relatedness of auxiliaries compared to the nestlings in their territories. I confirmed cooperative polygamy with genetic techniques for the first time in Harris's hawks and found 58% of juvenile hawks delayed dispersal for at least 6 mo. Using the dual benefits framework, I found social associations that formed through delayed dispersal followed predictions for resource-defense benefits, but sociality among mature non-related hawks more closely followed predictions associated with collective action benefits, specifically reproductive output was significantly …
Date: August 2021
Creator: Gibbons, Andrea L
System: The UNT Digital Library

Studies on the Fibrinolytic Pathway in Zebrafish

Fibrinolysis pathway is an important mechanism for dissolution of fibrin clot by the action of plasmin which is formed from plasminogen, a zymogen via the action of plasminogen activators, i.e. tissue plasminogen activator and urinary plasminogen activator. The regulation of fibrinolysis system in vivo is maintained by plasminogen activators and natural inhibitors i.e. α2-antiplasmin, α2-macroglobulin, Thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor 1 and 2 (PAI-1and PAI-2). There are several fibrinolytic assays developed for human plasma but there are no reports describing fibrinolytic assay using zebrafish plasma. In this study, a fibrinolytic assay via using small amount of zebrafish plasma was developed. This assay was performed under different conditions; one by the addition of exogenous tissue plasminogen activator alone to the pooled zebrafish plasma along with calcium chloride and thromboplastin, second Dade ACTIN was used instead of tissue plasminogen activator and third Dade ACTIN along with thromboplastin was used. Epsilon amino caproic acid (EACA), a synthetic antifibrinolytic agent was used at different concentrations to inhibit fibrinolysis successfully. Similar experiments were performed on human plasma as well to check the applicability of the assay to humans and positive results were obtained. Furthermore, knockdown of tissue plasminogen activator and plasminogen genes …
Date: August 2021
Creator: Gill, Jaspreet Kaur
System: The UNT Digital Library

Biomonitoring at Dallas-Fort Worth International Airport: Relating Watershed Land Use with Aquatic Life Use

The Dallas-Fort Worth International (DFW) Airport is located in a densely urbanized area with one of the fastest-growing populations in the U.S.A. The airport property includes a large tract of "protected" riparian forest that is unique to the urban surroundings. This dissertation explores variables that influence the benthic macroinvertebrate community structure found in urbanized prairie streams that were initially assessed by the University of North Texas (UNT) Benthic Ecology Lab during four, non-consecutive biomonitoring studies (2004, 2005, 2008, and 2014) funded by the DFW Airport. Additionally, land use analysis was performed using 5-meter resolution satellite imagery and eCognition to characterize the imperviousness of the study area watersheds at multiple scales. Overall, flow conditions and imperviousness at the watershed scale explained the most variability in the benthic stream community. Chironomidae taxa made up 20-50% of stream communities and outperformed all other taxa groups in discriminating between sites of similar flows and urban impairments. This finding highlights the need for genus level identifications of the chironomid family, especially as the dominant taxa in urban prairie streams. Over the course of these biomonitoring survey events, normal flow conditions and flows associated with supra-seasonal drought were experienced. Prevailing drought conditions of 2014 did not …
Date: August 2021
Creator: Harlow, Megann Mae Lewis
System: The UNT Digital Library
Ecological Responses to Severe Flooding in Coastal Ecosystems: Determining the Vegetation Response to Hurricane Harvey within a Texas Coast Salt Marsh (open access)

Ecological Responses to Severe Flooding in Coastal Ecosystems: Determining the Vegetation Response to Hurricane Harvey within a Texas Coast Salt Marsh

Vegetative health was measured both before and after Hurricane Harvey using remotely sensed vegetation indices on the coastal marshland surrounding Galveston Island's West Bay. Data were recorded on a monthly basis following the hurricane from September of 2005 until September of 2019 in order to document the vegetation response to this significant disturbance event. Both initial impact and recovery were found to be dependent on a variety of factors, including elevation zone, spatial proximity to the bay, the season during which recovery took place, as well as the amount of time since the hurricane. Slope was also tested as a potential variable using a LiDAR-derived slope raster, and while unable to significantly explain variations in vegetative health immediately following the hurricane, it was able to explain some degree of variability among spatially close data points. Among environmental factors, elevation zone appeared to be the most key in determining the degree of vegetation impact, suggesting that the different plant assemblages that make up different portions of the marsh react differently to the severe flooding that took place during Harvey.
Date: August 2021
Creator: Hudman, Kenneth Russell
System: The UNT Digital Library

Studies on Intrinsic Coagulation Pathway of Zebrafish

In the past couple of decades, the zebrafish has been widely used to study hemostatic disorders. In this study, we generated a CRISPR/Cas9 mediated zebrafish mutant that contains a 55-nucleotide insertion in exon 29 of the von Willebrand factor (vwf) gene. The mutants had impaired ristocetin-mediated agglutination of whole blood, prolonged PTT and more bleeding in the lateral incision compared to wild-type fish. The bleeding phenotype observed here is similar to the phenotype observed in vwf knockout mice and patients with von Willebrand disease (VWD). The mutant model developed here can thus be used for exploring the role of Vwf in angiogenesis and for developing gene therapy. The deficiency of VWF causes VWD and the etiology remains unknown in 30% of Type 1 VWD cases. Previous studies have identified that the ABO blood group and ST3GAL4 (glycosyltransferases) are involved in the regulation of VWF levels. Since VWF is heavily glycosylated, we hypothesized that other glycosyltransferases may also be involved in regulating VWF. We performed a knockdown screen of 234 glycosyltransferase genes and identified 14 genes that altered Vwf levels. The sequencing of these genes in Type 1 VWD patients could help identify novel mutations to decipher the molecular basis for …
Date: August 2021
Creator: Iyer, Neha
System: The UNT Digital Library

Ozone Pollution Monitoring and Population Vulnerability in Dallas-Ft. Worth: A Decision Support Approach

In urban environments, ozone air pollution, poses significant risks to respiratory health. Fixed site monitoring is the primary method of measuring ozone concentrations for health advisories and pollutant reduction, but the spatial scale may not reflect the current population distribution or its future growth. Moreover, formal methods for the placement of ozone monitoring sites within populations potentially omit important spatial criteria, producing monitoring locations that could unintentionally underestimate the exposure burden. Although air pollution affects all people, the combination of underlying health, socioeconomic and demographic factors exacerbate the impact for socially vulnerable population groups. A need exists for assessing the spatial representativeness and data gaps of existing pollution sensor networks and to evaluate future placement strategies of additional sensors. This research also seeks to understand how air pollution monitor placement strategies may neglect social vulnerabilities and therefore, potentially underestimate exposure burdens in vulnerable populations.
Date: August 2021
Creator: Northeim, Kari M.
System: The UNT Digital Library
Flow-Recruitment Relationships of Smallmouth Buffalo (Ictiobus bubalus) in Three Texas River Basins (open access)

Flow-Recruitment Relationships of Smallmouth Buffalo (Ictiobus bubalus) in Three Texas River Basins

This project focused on the relationship between instream flows and smallmouth buffalo (Ictiobus bubalus) recruitment in the Gulf Coastal Plain of Texas. The flow regime is the dominant factor in lotic systems and, consequently, the relationship between instream flows, including impacts to natural flow regimes, and life-history is a subject of growing interest. Smallmouth buffalo is a good model to investigate the relationship between river flows and variable interannual recruitment success of periodic life-history strategist fish species. Smallmouth buffalo were collected from the Brazos, Colorado, and Guadalupe Rivers of Texas, U.S.A., and otoliths were extracted from individuals in the field and sectioned and photographed in the lab. Photographs of sectioned otoliths were used to estimate age and thus the year in which the individual was spawned by counting back from the time of capture. Population age structure (i.e. a ‘state' or condition at a point in time) was used to infer effects of flow variation on a rates-based process (i.e. recruitment). After controlling for mortality using recruitment index values, interannual variation in recruitment was modeled using multiple components of the flow regime quantified as indicators of hydrologic alteration (IHA) variables based on daily discharge data from USGS gaging stations in …
Date: August 2021
Creator: Reeves, Cole Griffin
System: The UNT Digital Library
Analysis of the Accumulation, Toxic Effects, and Risk of Persistent Organic Pollutants in Pinnipeds (open access)

Analysis of the Accumulation, Toxic Effects, and Risk of Persistent Organic Pollutants in Pinnipeds

The present studies determine the accumulation of persistent organic pollutants (POPs) in three pinniped species, evaluate the relationship with relevant biomarkers of exposure, and calculate toxic effect thresholds. Stranded harp and hooded seals were found to be accumulating PBDEs at levels which could pose a based on threshold levels determined in this study. Northern fur seals are accumulating all three classes of POPs (PCBs, PBDEs, and OCPs) with significant relationships being seen with blubber percent lipid. Correlations between contaminant concentrations and expression levels of relevant biomarkers were seen potentially indicating an effect on multiple pathways. Overall risk can be hard to determine due to factors such as sex and age. Broad threshold response values and hazard quotients were calculated for toxic effect endpoints in pinnipeds. Overall these results suggest that certain populations of pinnipeds are at high risk of experiencing toxic effects due to POP exposure, but it is important to understand effects even at lower concentrations. The relationship between exposure, toxic effects, and other stressors, both environmental and physiological, can impact the overall fitness and survival of pinnipeds.
Date: August 2021
Creator: Soulen, Brianne K
System: The UNT Digital Library