Thesis (Ph.D.)--University of North Carolina Wilmington, 2008. / Title from PDF title page (viewed May 25, 2009) Includes bibliographical references (p. 33-35)

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: [37]-41)

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : [51]-54).

Comparative sequence analyses were performed with members of the Solanaceae and the Brassicaceae. These studies investigated genomic organization, determined levels of microcolinearity, identified orthologous genes and investigated the molecular basis of trait differences. The first analysis was performed by comparison of tomato (Solanum lycopersicum) genomic sequence (119 kb) containing the JOINTLESS1 (J1) locus with orthologous sequences from two potato species, a diploid, Solanum bulbocastanum (800-900 Mb, 2N=2X=24), and a hexaploid, Solanum demissum (2,700 Mb, 2N=6X=72). Gene colinearity was well maintained across all three regions. Twelve orthologous open reading frames were identified in identical order and orientation and included three putative J1 orthologs with 93-96% amino acid sequence identity in both potato species. Although these regions were highly conserved, several local disruptions were detected and included small-scale expansion/contraction regions with intergenic sequences, non-colinear genes and transposable elements. Three putative Solanaceous-specific genes were also identified in this analysis. The second analysis was performed by comparison of a Thellungiella halophila (T. halophila) genomic sequence (193 kb) containing the SALT OVERLY SENSITIVE1 (SOS1) locus with the orthologous sequence (146 kb) in Arabidopsis thaliana (Arabidopsis). T. halophila is a halophytic relative of Arabidopsis thaliana that exhibits extreme salt tolerance. Twenty-five genes, including the putative T. halophila SOS1 (ThSOS1), showed a high degree of colinearity with Arabidopsis genes in the corresponding region. Although the two sequences were significantly colinear, several local rearrangements were detected which were caused by tandem duplications and inversions. Three major expansion/contraction regions in T. halophila contained five LTR retrotransposons which contributed to genomic size variation in this region. ThSOS1 shares similar gene structure and sequence with Arabidopsis SOS1 (AtSOS1), including 11 transmembrane domains and a cyclic nucleotide-binding domain. Three Simple Sequence Repeats (SSRs) were detected within a 540 bp region upstream of the putative translational start site in ThSOS1. The (CTT)n repeat is present in different copy numbers in ThSOS1 (18 repeats) and AtSOS1 (3 repeats). When present in the 5' UTRs of some Arabidopsis genes, (CTT)n serves as a putative salicylic acid responsive element. These SSRs may serve as cis-acting elements affecting differential mRNA accumulation of SOS1 in the two species.

This diploma thesis deals with the use of thermal analysis in the study on effects of microbial inhibitors. The main aim of this work was to determine the utilization of the method, which is mainly used in different fields of science and research. Three bacterial strains: Cupriavidus necator H16, its mutant strain Cupriavidus necator PHB-4 and Halomonas halophila, were used as model microorganisms. The inhibitory effect of levulinic acid on growth and metabolic activity was monitored by microcalorimetry. It was found that bacteria were able to adapt to levulinic acid to a certain concentration - Cupriavidus necator to 5 g/l and Halomonas halophila to 2 g/l. The thermal analysis results were compared to a conventional method, which is commonly used to study the growth of microorganisms.

Seagrass ecosystems are intense carbon sinks, but they can also emit greenhouse gases (GHG), such as carbon dioxide (CO2) and methane (CH4), to the atmosphere. Yet, GHG emissions by seagrasses are not considered when estimating global CH4 production rates by natural sources, although these estimations will help predict future scenarios and potential changes in CH4 emissions. In addition, the effect of warming on GHG emissions by seagrasses has not yet been reported. The present study aims to assess the CO2 and CH4 production rates by vegetated and adjacent bare sediment of a monospecific seagrass meadow (Halophila stipulacea) located in the central Red Sea. We measured CH4 and CO2 fluxes and their isotopic signatures by cavity ringdown spectroscopy on chambers containing vegetated and bare sediment. The fluxes were measured at temperatures from 25 °C (winter seawater temperature) to 37 °C to cover the natural thermal range and future seawater temperatures in the Red Sea. Additional parameters analyzed included changes in the sediment microbial community composition, sediment organic matter, organic carbon, nitrogen, and phosphorus concentration. We detected up to 100-fold higher CH4 (up tp 571.65 µmol CH4 m−2 d−1) and up to six-fold higher CO2 (up to 13,930.18 µmol CO2 m−2 d−1) fluxes in vegetated sediment compared to bare sediment, and an increase in CH4 and CO2 production with increasing temperature. In contrast, CH4 and CO2 production rates decreased in communities that were maintained at 25 °C, while communities that were exposed to prolonged darkness showed a decrease in CH4 and an increase in CO2 production rates. However, only minor changes were seen in the microbial community composition with increasing temperatures. These results show that GHG emissions by seagrasses might be affected by natural temperature extremes and warming due to climate change in the Red Sea. The findings will have critical implications for the estimation of natural GHG sources, especially when predicting future changes in the global CH4 budget.

During the growing seasons of 1999 and 2000 five experiments were performed to test growth of the seagrass Halodule beaudettei (shoal-grass) in nursery pond conditions. Sediment oxidation state, sediment source, container type, flow regime, and light transmittance were tested to improve nursery pond cultivation techniques and to test assumptions about the decline of seagrasses in Galveston Bay, Texas. Oxidized and reduced sediments exhibited no statistical difference as mean percent change in the number of stems of shoal-grass, after 47 days. Sediment from three source locations, West Bay, East Beach Lagoons, and the experimental pond bottoms, showed no significant difference in the mean percent change in the number of stems of shoal-grass at 48 and 95 days. A statistical difference was seen in the container type experiment, trays versus pots, at 48 days where shoal-grass had double the number of stems produced in trays; however no significant difference was found at 93 days. A significant difference was found in the flow regime experiment, no-flow versus flow, at 47 days in the mean percent change of shoal-grass with double the number of stems produced in the flow regime. Significant differences were observed between the low light and high light treatments with shoal-grass, widgeongrass (Ruppia maritima), star grass (Halophila engelmannii), and turtlegrass (Thalassia testudinum), with survival and growth occurring in the high light treatment and decline and death occurring in the low light treatment. The importance of reduced sediment may have been overstated in the past as sediment reduction occurs rapidly with submersion. It appears that while West Bay sediment did not have a deleterious effect on shoal-grass, West Bay simulated light conditions did. Container type seems to be important at first but not so much in the long term. Some flow, water movement, or current appears to be important.

This master thesis deals with the development of a minibioreactor for microbial biotechnologies. The AlgaTox system – an analytical photobioreactor from BVT Technologies – was the default unit of the new device. The working volume of the new minibioreactor is in the range of 4 to 8 ml. The minibioreactor was composed of a minithermostat, a reaction vessel, an oxygen electrode, a temperature and pH probe, accessories for the supply of air to the liquid and an insertion for the transport of liquid from / to the reactor. The functionality of the assembled device and its characteristics were measured. Furthermore, an operating procedure for the decontamination process using a hydrogen peroxide mist was developed for the new equipment. An operating procedure for culturing microorganisms in a minibioreactor was also set up. Pilot cultivations of Halomonas halophila were demonstrated in the prepared equipment. In these cultivations, three assemblies for air supply to the liquid were tested. However, none of the assemblies was able to provide a sufficient supply of oxygen to cell culture – the dissolved oxygen value always dropped to 0%. For the further development, a new assembly was designed for the supply of air to the liquid - an aeration ring from a membrane tube.

Seagrass meadows, like coral reefs, are in decline globally but are often neglected in marine policy and conservation despite their equally critical ecosystem services. Both habitats can be heavily impacted by wave surges, rainfall-induced earth movement and flooding, changes to water temperature, salinity, and acidity, and increased levels of turbidity—all occurring at increased rates due to a changing global climate. We demonstrate that multispectral satellite imagery, geospatial tools, and classification techniques can be used to inform management by identifying and quantifying changes in seagrass distribution and the presence of sediment-related threats. Results from Dominica indicate near-shore seagrass habitat area increased by 195.7 hectares between 2016 and 2019, suggesting a continued expansion of Halophila stipulacea. Further analysis showed 22.4 hectares of accreted coastal sediment and 1362.2 hectares of suspended sediment captured, placing 424.4 hectares of sensitive reef area at risk of experiencing tissue abrasion or reduced photosynthetic activity. Our methods can be used by marine resource managers and policy makers to inform decisions relating to fisheries production, emissions trading, disaster risk mitigation, and invasive species monitoring, facilitating sustainable growth in the blue economy.

The physiological responses to salt stress were measured in Chenopodium quinoa. In a greenhouse experiment, salt water was applied to the quinoa varieties, Chipaya and KU-2, and to the model halophyte Thellungiella halophila to assess their relative responses to salt stress. Height and weight data from a seven-week time course demonstrated that both cultivars exhibited greater tolerance to salt than T. halophila. In a growth chamber experiment, three quinoa cultivars, Chipaya, Ollague, and CICA 17 were hydroponically grown and physiological responses were measured with four salt treatments. Tissues collected from the growth chamber treatments were used to obtain leaf succulence data, tissue ion concentrations, compatible solute concentrations, and RNA for real-time PCR. Stomatal conductance and fresh weight were measured to determine the degree of stress and recovery. The expression profiles of SOS1, NHX1, and TIP2, genes involved in salt stress, showed constitutive expression in root tissue and up-regulation in leaf tissue in response to salt stress. These data suggest that quinoa tolerates salt through a combination of exclusion and accumulation mechanisms.