Characterisation of CD154+ T cells following ex vivo allergen stimulation illustrates distinct T cell responses to seasonal and perennial allergens in allergic and non-allergic individuals

Background Allergic sensitisation has been ascribed to a dysregulated relationship between allergen-specific Th1, Th2 and regulatory T cells. We sought to utilise our short-term CD154 detection method to further analyse the relationship between these T cell subsets and investigate differences between seasonal and perennial allergens. Using peripheral blood samples from grass-allergic, cat-allergic and healthy non-atopic subjects, we compared the frequencies and phenotype of CD154-positive T helper cells following stimulation with seasonal (grass) and perennial (cat dander) allergens. Results We identified a higher frequency of CD154+ T cells in grass-allergic individuals compared to healthy controls; this difference was not evident following stimulation with cat allergen. Activated Th1, Th2 and Tr1-like cells, that co-express IFNγ, IL4 and IL10, respectively, were identified in varying proportions in grass-allergic, cat-allergic and non-allergic individuals. We confirmed a close correlation between Th1, Th2 and Tr1-like cell frequency in non-allergic volunteers, such that the three parameters increased together to maintain a low Th2: Th1 ratio. This relationship was dysregulated in grass-allergic individuals with no correlation between the T cell subsets and a higher Th2: Th1 ratio. We confirmed previous reports of a late-differentiated T cell phenotype in response to seasonal allergens compared to early-differentiated T cell responses to perennial allergens. Conclusions The findings confirm our existing work illustrating an important balance between Th1, Th2 and Tr1-like responses to allergens in health, where Th2 responses are frequently observed, but balanced by Th1 and regulatory responses. We confirm previous tetramer-based reports of phenotypic differences in T cells responding to seasonal and perennial allergens

The Stratospheric Aerosol and Gas Experiment (SAGE III) on the International Space Station (ISS) Mission

The Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS) mission will provide the science community with high-vertical resolution and nearly global observations of ozone, aerosols, water vapor, nitrogen dioxide, and other trace gas species in the stratosphere and upper-troposphere. SAGE III/ISS measurements will extend the long-term Stratospheric Aerosol Measurement (SAM) and SAGE data record begun in the 1970s. The multi-decadal SAGE ozone and aerosol data sets have undergone intense scrutiny and are considered the international standard for accuracy and stability. SAGE data have been used to monitor the effectiveness of the Montreal Protocol. Key objectives of the mission are to assess the state of the recovery in the distribution of ozone, to re-establish the aerosol measurements needed by both climate and ozone models, and to gain further insight into key processes contributing to ozone and aerosol variability. The space station mid-inclination orbit allows for a large range in latitude sampling and nearly continuous communications with payloads. The SAGE III instrument is the fifth in a series of instruments developed for monitoring atmospheric constituents with high vertical resolution. The SAGE III instrument is a moderate resolution spectrometer covering wavelengths from 290 nm to 1550 nm. Science data is collected in solar occultation mode, lunar occultation mode, and limb scatter measurement mode. A SpaceX Falcon 9 launch vehicle will provide access to space. Mounted in the unpressurized section of the Dragon trunk, SAGE III will be robotically removed from the Dragon and installed on the space station. SAGE III/ISS will be mounted to the ExPRESS Logistics Carrier-4 (ELC-4) location on the starboard side of the station. To facilitate a nadir view from this location, a Nadir Viewing Platform (NVP) payload was developed which mounts between the carrier and the SAGE III Instrument Payload (IP)

Thyroid hormone binding to brain nuclear extracts during smoltification in coho salmon

Thesis (Ph.D.) University of Alaska Fairbanks, 1991Salmon complete a metamorphosis called smoltification prior to entering salt water. Increased thyroid activity, olfactory imprinting, and chemical and structural changes in the brain are known to occur at this time. This study was undertaken to determine if triiodothyronine (T\sb3) binding to brain nuclear extracts changes during smoltification. During this investigation serum thyroxine (T\sb4) concentrations increased three fold during smoltification coincident with changes in coloration and morphology and surged again during downstream migration to six times presmolt concentrations. Using ultrafiltration assays, homologous displacement experiments of KCl extracts of recovered brain cell nuclei indicated that maximal binding capacity increased during smoltification and down-stream migration. The increase in receptor concentration lagged the increase in serum thyroxine by one week. Dissociation constants increased during smolt transformation but declined abruptly during down-stream migration. However, dissociation constants did not change during smoltification if nuclear extracts had been previously incubated at room temperature to remove endogenous ligand. Dissociation rate increased significantly, coincident with the increase in receptor concentration measured by homologous displacement. The maximal probable percent occupancy of available receptors increased from 60% before to greater than 95% during the smolt transformation climax. These results provide evidence that thyroid hormone receptors participate in brain development and olfactory imprinting in smolting salmon

Paleoindicators of meromixis

This study was undertaken to ascertain whether meromictic lakes could be differentiated from holomictic lakes on the basis of their surficial profundal sediments. Surface sediment cores (15 cm long) were collected from both the littoral and profundal zones of four meromictic and six holomictic lakes and analyzed for total number of fossil chironomid headcapsu~es, chlorophyll and carotenoid degradation products as well as \ iron and manganese concentrations. Littoral and profundal comparisons of the surface sediments were made between the two lake types using the Mann-Whitney U test. Iron, manganese and the iron to manganese ratio in the littoral sediments of meromictic lakes were significantly lower than those found in the littoral sediments of holomictic lakes. The observed differences are believed to represent an artifact of the significantly higher carbonate concentrations found in three of the four meromictic lakes studied. Profundal and littoral to profundal ratio comparison between holomictic and meromictic lakes suggest that the significantly lower iron and higher carotenoid concentrations in meromictic profundal sediments were a con~equence of meromixis. However, the overlap in distribution exhibited by both iron and carotenoid degradation products between the two lake types was sufficiently large in this study to nullify their use as a means of differentiating meromictic from holomictic lakes. A long core (4.25 m) was removed from the deepest part of the meromictic Crawford Lake (Ontario), sectioned at 5 cm intervals, and analyzed to assess when meromixis occurred, based on its fossil record. Temporal changes in the total number of chironomid headcapsules, and chlorophyll and carotenoid sediment degradation products were closely correlated with organic matter, indicating in my opinion that extensive redeposition of littoral chironomid headcapsules in the profundal zone has occurred. Temporal variations in carotenoid degradation products, in response to changes in organic matter, obscured increased preservation that may have occurred as a consequence of meromixis. Temporal variations in iron and manganese suggest that relatively stable redox conditions have existed throughout most of the lake's history. Therefore it would appear that Crawford Lake has been meromictic since its inception

The value of arboreta in South Africa

Significance:• Arboreta are documented, living collections of ligneous species cultivated for research, education and display.• Arboreta are a valuable resource for the forestry industry as gene banks.• Arboreta, together with botanic gardens, form a useful network of sentinel sites for plant pathogens and invasive species.• A survey of the species composition and status     of  arboreta in South Africa would be an important contribution to our botanical knowledge

The influence of root chilling on the hydraulic characteristics of selected Eucalyptus taxa.

Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2008.The hydraulic conductance of a plant is a significant factor in determining th

Mutation accumulation in exponentially growing populations

Stochastic models of mutation accumulation in exponentially growing cellular populations are widely used to quantify cancer and bacterial evolution. Across manifold scenarios, recurrent research questions are: how many cells exist with a given set of alterations, and how long will it take for these cells to appear. These questions have been tackled in special cases, often within a branching processes framework. However, the general situation of cells sequentially acquiring an arbitrary number of mutations which may be selectively advantageous, neutral, or disadvantageous remains unaddressed. Here, we consider this setting in the biologically relevant limiting regimes of large times and small mutation rates. We provide analytic expressions for the number, and arrival time, of cells with $n$ mutations. Universal probability distributions for both quantities are presented, and the consequences of our results on cancer driver mutation accumulation and bacterial fluctuation assays are highlighted

Sequential mutations in exponentially growing populations

Stochastic models of sequential mutation acquisition are widely used to quantify cancer and bacterial evolution. Across manifold scenarios, recurrent research questions are: how many cells are there with n alterations, and how long will it take for these cells to appear. For exponentially growing populations, these questions have been tackled only in special cases so far. Here, within a multitype branching process framework, we consider a general mutational path where mutations may be advantageous, neutral or deleterious. In the biologically relevant limiting regimes of large times and small mutation rates, we derive probability distributions for the number, and arrival time, of cells with n mutations. Surprisingly, the two quantities respectively follow Mittag-Leffler and logistic distributions regardless of n or the mutations' selective effects. Our results provide a rapid method to assess how altering the fundamental division, death, and mutation rates impacts the arrival time, and number, of mutant cells. We highlight consequences for mutation rate inference in fluctuation assays

GPS disciplined RFSoC synchronization, timing, and performance characterization in bistatic radar systems

Distributed radar geometries offer multiple advantages over monostatic pulse-Doppler radar, but synchronizing frequency and timing for transmitting and receiving nodes in a distributed system is required to more accurately detect range and Doppler frequency. A GPS-disciplined bistatic radar synchronization system design running on an RF System-on-Chip (RFSoC) transceiver and GPS-disciplined precision timing reference is detailed, and the features and limitations of these two individual systems are examined. To better understand error tolerances of relevant signals produced by the timing reference used in the synchronization system, in-depth analyses of frequency drift, timing drift, and jitter are conducted and described both with and without GPS disciplining. Custom-designed FPGA IP designed to implement transmit and receive pulse Doppler radar functionality in the RFSoC-based system is introduced

Wading bird foraging ecology in a disturbed mangrove estuary in northwest Ecuador : commercial shrimp ponds vs. natural mangrove mudflats

I compared wading bird foraging ecology in commercial shrimp ponds and natural mangrove mudflats in the Muisne River Estuary in northwest Ecuador. I estimated foraging habitat suitability by observing the foraging efficiency, diet, and behavior of great (Ardea alba) and snowy (Egretta thula) egrets, censusing birds, and measuring prey availability (i.e. prey density, standing crop, water depth, and diversity). Great egrets had greater foraging efficiency in shrimp ponds, while snowy egret foraging efficiency was greater on mudflats. Over 85% of prey items in snowy egret boluses were from shrimp ponds. Mean density, standing crop, length, and mass of prey items was significantly greater in shrimp ponds, but availability was limited by water depth and diversity. Great and snowy egrets utilized shrimp ponds as their primary foraging grounds, while all other diurnal wading bird species foraged primarily on mudflats, where the diversity of wading birds and their prey was greatest