Bacteriophage Lambda (λ) has played a historical role as an essential model contributing to our current understanding of molecular genetics. Lambda’s major capsid protein “gpD” occurs on each capsid at 405 to 420 copies per phage in homotrimeric form and functions to stabilize the head and likely to compact the genomic DNA. The interesting conformation of this protein allows for its exploitation through the genetic fusion of peptides or proteins to either the amino or carboxy terminal end of gpD, while retaining phage assembly functionality and viability. The lytic nature of λ and the conformation of gpD in capsid assembly makes this display system superior to other display options. Despite previous reports of λ as a phage display candidate, decorative control of the phage remains an elusive concept. The primary goal of this study was to design and construct a highly controllable head decoration system governed by two genetic conditional regulation systems; plasmid-mediated temperature sensitive repressor expression and bacterial conditional amber mutation suppression. The historical λ Dam15 conditional allele results in a truncated gpD fragment when translated in nonsuppressor, wild-type E. coli cells, resulting in unassembled, nonviable progeny. I sequenced the Dam15 allele, identifying an amber (UAG) translational stop at the 68th codon. Employing this mutant in combination with a newly created isogenic cellular background utilizing the amber suppressors SupD (Serine), SupE (Glutamine), SupF (Tyrosine) and Sup— (wild type), we sought to control the level of incorporation of undecorated gpD products. As a second dimension, I constructed two separate temperature-inducile plasmids whereby expression of either D or D::eGFP was governed by the λ strong λ CI[Ts]857 temperature-sensitive repressor and expressed from the λ PL strong promoter. Our aim was to measure the decoration of the λ capsid by a D::gfp fusion under varying conditions regulated by both temperature and presence of suppression. This was achieved utilizing this controllable system, enabling the measurement of a variable number of fusions per phage based on diverse genetic and physical environments without significantly compromising phage viability. Surprisingly, both SupE and SupF showed similar levels of Dam15 suppression, even though sequencing data indicated that only SupE could restore the native gpD sequence at amino acid 68 (Q). In contrast, SupD (S), conferred very weak levels of suppression, but imparted an environment for very high decoration of gpD::eGFP per capsid, even at lower (repressed) temperatures. The presence of albeit few wild-type gpD molecules allowed for an even greater display than that of the perceived “100%” decoration scenario provided by the nonsuppressor strain. It appears that the lack of wild-type gpD does not allow for the space required to display the maximum number of fusions and in turn creates an environment that affects both phage assembly and therefore phage viability. Finally, the use of Western blotting, confirmed the presence of gpD::eGFP fusion decoration by employing a polyclonal anti-eGFP antibody. The significance of this work relates to the unique structure of λ’s capsid and its ability to exploit gpD in the design of controlled expression, which is guiding future research examining the fusion of different therapeutic peptides and proteins. Furthermore this approach has important implications specifically for the design of novel vaccines and delivery vehicles for targeted gene therapy in which steric hindrance and avidity are important concerns. The execution of this project employed basic bacterial genetics, phage biology and molecular biology techniques in the construction of bacterial strains and plasmids and the characterization of the phage display system.

Invasive plants cause ecosystem degradation throughout the world, including the reduction of native plant density and diversity, and changes in ecosystem structure and function. Woody weeds often grow faster than native species and in invaded habitats produce larger and/or more seed and outshade other mid- and under-storey species. Boneseed Chrysanthemoides monilifera ssp. monilifera (L.) T. Norl. has caused the degradation of many temperate woodlands in Australia and has not yet reached its full potential distribution in this country. The control of this weed is therefore a high priority in Australia. Biological control agents have not controlled boneseed populations to date and no detailed integrated control strategies exist for different densities of mature boneseed plants and soil seed banks in native vegetation of varying levels of degradation. Fire, herbicides and manual plant removal have previously been used to control boneseed; however, substantial landscape scale control has not yet been achieved. Boneseed population control experiments were undertaken in two temperate woodlands in Victoria, Australia. In highly degraded temperate grassy woodlands at the You Yangs Regional Park west of Melbourne in Victoria and in a highly diverse native closed woodland at Arthurs Seat State Park in south-eastern Victoria. Several combinations of the weed control techniques of fire, herbicide application, hand-pulling of seedlings and distribution of competitive native grasses were found to control both mature boneseed populations and the large reserves of viable boneseed seeds in the soil. The efficacy of controlled burning, and the combination and timing of control techniques were found to vary according to differing densities of boneseed plants, viable soil seed banks and post-fire emergent seedlings. Where sufficient fine fuel existed, a warm, even, autumn burn consumed above ground biomass, killed the majority of viable boneseed seed in the soil, and caused the remaining boneseed seed to germinate. Spraying with glyphosate herbicide was as effective as metsulfuron-methyl herbicide for killing boneseed seedlings along with the secondary climbing weed Billardiera heterophylla (Lindl.) L.W.Cayzer & Crisp after fire. However, the use of glyphosate also killed all native species, resulting in bare ground. After fire in species rich vegetation, boneseed was eliminated where seed of the native C3 grass Poa sieberiana Spreng. had been broadcast onto the post fire ash-bed, and seedlings had been sprayed five months after the burn or where seedlings had been sprayed 12 months after burning. Boneseed control occurred when seedlings were sprayed five months after the burn. In degraded vegetation few boneseed seedlings remained where seedlings were sprayed 17 months after fire. Where insufficient rainfall occurred, hand-pulling flowering boneseed seedlings prevented new seed fall for 6 to 12 months. Suggestions are made for the integration of these methods with the establishment and proliferation of biological control agents. A new protocol for utilising several integrated control strategies for boneseed and other woody weeds in a mosaic at both the site and landscape scale is described. A mosaic would allow for a variety of native species responses to fire and other control methods and thus lead to heterogeneous ages and structures within the native vegetation following weed control. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1457770 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2009

Title from second page of PDF document. Includes bibliographical references (p. 145-173).

Marine epibenthic communities are influenced by both pre- and post-recruitment processes. For instance, the larval supply and cues that influence settlement (pre-recruitment), as well as the growth and mortality of individuals (post-recruitment), may differ across reef type and depth. Determining the relative influence of these processes is important to understanding how epibenthic communities can develop in a region. Using both a recruitment experiment that controlled grazing by urchins and in situ photographic surveys of epibenthic communities, this study examined the recruitment and composition of epibenthos on natural limestone and artificial reefs in the eastern Gulf of Mexico (eGOM). In the experiment, tiles that were open to urchin grazing had lower percent cover of algae (-12%) and higher cover of crustose coralline algae (CCA) (13%) than those that excluded urchins. Patterns in tile cover were likely the result of CCA either resisting grazing mortality or recolonizing exposed areas after algae were removed. Prevalence of estuarine species on inshore tiles was indicative of variation in recruitment across depth. Urchin density was positively correlated with the structural complexity of the habitats, which was higher on artificial reefs than natural ones, a factor that potentially had important effects on several observed patterns. Results from photographic surveys indicated that natural reef communities had higher algal cover and lower cover of invertebrates (e.g., corals and hydroids) than artificial reefs. These findings were consistent with previous work conducted in both temperate and tropical ecosystems, and suggested that grazing from urchins plays an important role in shaping epibenthic community structure in the subtropical eGOM.

This thesis examined the effect of differences in body surface area-to-lean body mass ratio (AD/LBM) on core temperature cooling rates during cold water immersion (2°C, CWI) and temperate water immersion (26°C, TWI) following exercise-induced hyperthermia (end-exercise rectal temperature of 40°C). Individuals with a High AD/LBM (315 cm2/kg) had a ~1.7-fold greater overall rectal cooling rate relative to those with Low AD/LBM (275 cm2/kg) during both CWI and TWI. Further, overall rectal cooling rates during CWI were ~2.7-fold greater than during TWI for both the High and Low AD/LBM groups. Study findings show that AD/LBM must be considered when determining the duration of the immersion period. However, CWI provides the most effective cooling treatment for EHS patients irrespective of physical differences between individuals.

No description available.

No description available.

To evaluate the potential impacts of future climate change on a temperate reservoir, I used a calibrated water quality and hydrodynamic model validated using three years of data (2007-2009) from Deer Creek Reservoir (Utah). I evaluated the changes due to altered air temperatures, inflow rates, and nutrient loads that might occur under Global Climate Change (GCC). I developed methods to study GCC on reservoirs. I produced Average Water Temperature Plots, Stratification Plots, and Total Concentration Plots. Average Water Temperature Plots show the sensitivity of the water temperature to various parameters. Stratification Plots quantify stratification length and strength as well as ice-cover periods. Total Concentration Plots analyze the reservoir as a whole concerning water quality parameters. Increasing air temperature increased the water temperature, lengthened stratification time, increased stratification strength, decreased the ice-cover period, decreased the total algae concentration, decreased the flows, and caused peak nutrient concentrations to occur earlier. Decreasing flows caused increased water temperature, shorter stratification periods, weaker stratification, and increased nutrient concentrations. Increasing phosphate concentrations caused increases in total algae, dissolved oxygen, and phosphate concentrations. Variations in Nitrate-Nitrite concentrations did not influence the tested parameters. I found that the reservoir is only sensitive to these changes during the spring and summer. The tools which I developed were used to run the model scenarios, organize the data, and plot the results. They can be used on other reservoirs and for other water quality parameters.

I analyzed and compared impacts from global climate change (GCC) and land use change to Deer Creek (United States) a temperate reservoir and Aguamilpa (Mexico), a tropical reservoir by using calibrated CE-QUAL-W2 (W2) water quality and hydrodynamic models based on field data over an extended time period. I evaluated and compared the sensitivity to predicted GCC and land use changes. I individually evaluated changes to air temperature (TAIR), inflow rates (Q), and nutrient loads (PO4-P and NO3-NO2-N) followed by analysis of worst case scenarios. I developed analysis methods using indexes to represent the total reservoir change calculated using the total parameter mass (i.e., algae, dissolved oxygen, total dissolved solids) normalized by the reservoir volume to eliminate apparent mass changes due to volume changes. These indexes have units of average concentrations, but are better thought of as a global reservoir index or normalized concentration. These indexes allow analysis of the total reservoir and not just specific zones. Total normalized algal concentrations were impacted more by changes in nutrient inflows (land use) in both reservoirs than to changes in TAIR and Q. For Deer Creek, PO4-P changes significantly increased normalized algal concentrations in the reservoir and in dam releases when PO4-P inflow was increased by 50%. Aguamilpa was more sensitive to NO3-NO2-N changes, exhibiting significant increases in normalized algal concentration for the +50% NO3-NO2-N simulation. Both reservoirs showed small changes to normalized algal concentration for the +3ºC TAIR simulation with the largest changes occurring during warm seasons. However, Deer Creek exhibited decreased total algal levels when TAIR was increased by 3ºC while Aguamilpa showed increased total algal levels with the 3ºC increase in TAIR. These contrasting trends, a decrease in Deer Creek and an increase in Aguamilpa, were produced by algae succession processes. Changes in Q affected normalized algal concentration in both reservoirs in different ways. In Aguamilpa, total algal levels increased under dry conditions while Deer Creek showed little general change associated with flow changes. Worst case scenario simulations, which included changing more than one parameter, showed that GCC changes can cause large impacts if they occur simultaneously with high nutrient loadings. These results begin to show how GCC could impact reservoirs and how these impacts compare to potential impacts from land use change. The results show that both temperate and tropical reservoirs are impacted by GCC but are more sensitive to nutrients. The methods, plots, and tools developed in this study can assist water managers in evaluating and studying GCC and land use changes effects in reservoirs worldwide.

Plantation and managed forests are major sink of atmospheric CO2 in North America and across the world. If properly managed, these forests may help to offset anthropogenic greenhouse gas emissions to mitigate climate change. This study investigated the impacts of climate variability, extreme weather events, and disturbance (thinning) on the growth and carbon (C) exchanges of a young temperate coniferous plantation forest (48-year-old white pine (Pinus strobus)) in the Great Lakes region in Canada using long-term eddy covariance flux observations. CO2 fluxes, as well as meteorological and soil variables were continuously measured from 2008 to 2021 (14 years) to estimate net ecosystem productivity (NEP), ecosystem respiration (RE), and gross ecosystem productivity (GEP). Soil respiration (Rs) was also measured using automatic soil chambers from 2017 to 2019. Selective thinning was conducted first time in this stand in January 2021 to remove approximately 1/3 of the basal area. Study results showed that climate conditions in the early growing season, from late May to mid-July, determined the overall strength of C uptake in any given year. However, above-average temperature and precipitation in the late growing season significantly reduced NEP and even in some cases, transformed the forest into a net C source for short periods due to large pulses of RE. Mean annual GEP, RE and NEP values were 1660 ±199, 1087 ±96 and 592 ±169 g C m-2 yr-1, respectively, from 2008 to 2021. Thinning did not significantly impact the C uptake of the forest as the stand remained a net C sink with an annual NEP of 648 g C m-2 yr-1 in 2021. Changes in annual GEP, RE and NEP in 2021 remained within the range of interannual variability over the study period. Overall, Rs accounted for roughly 89% of the annual RE in this stand. A complete understanding of the response of forest C dynamics to climate variability and thinning in young plantation forests is critical to guiding future forest management efforts for enhancing the growth and C uptake of these forest plantations to maximize their potential in support of providing nature-based climate solutions. / Thesis / Master of Science (MSc)