Variation in the Photosynthetic Heat Tolerance of Plants from Extreme Environments: The Influence of Heat Exposure and Environmental Context

University of Technology Sydney. Faculty of Science.Photosynthesis supports life on earth and is highly temperature dependent. Extreme temperatures can inhibit photosynthesis and damage the photosystem machinery, potentially limiting future productivity and plant survival. With increasing risk of extreme temperature exposure under climate change, plants may be pushed to the edge of their thermal limit, but at what point is a complex question. Temperatures that cause substantial damage to photosystems, encapsulated by heat tolerance thresholds, help to answer this question. On hot days leaf temperatures can spike multiple times, yet what we know of the variability of heat tolerance often comes from tests that vary in only one dimension – temperature. In Chapter 2, I demonstrated that varying combinations of heat characteristics can accumulate as heat doses and reveal multiple heat tolerance thresholds. By varying the heat dose, the thermal sensitivity of tolerance can also be examined, which is a first in plants. In Chapter 3, I followed the temporal effects of multiple exposures to extreme high temperatures, which potentially both reduced and delayed the capacity for repair to Photosystem II (PSII) with sustained photoinhibition present on the following day. Examining plants in less obviously extreme environments, alpine summers are predicted to be warmer and longer under climate change, potentially increasing heat stress for alpine plants. In Chapter 4, I explored the scarcely studied effect of elevated and extended growth temperature on the heat tolerance of Australian alpine species. While alpine plant species maintained surprisingly high photosynthetic heat tolerance, they only marginally increased their tolerance in response to warming, suggesting increased vulnerability to heat stress with long term climate change. The application of plant physiological heat tolerance in assessing future vulnerability to increasing temperatures under climatic change, however, is complicated. As I showed in Chapter 5, water availability plays an important role in the relationship between leaf and air temperature, which also influences the level of heat tolerance. Considered together, these components can considerably alter species predicted vulnerability assessments to high temperature. Combined, this work demonstrates that considering the multiple dimensions of high temperatures as heat doses, and the effects of complex relationships of water availability and temperature sources, widens the frame of photosynthetic thermal limits in plants experiencing extreme environments

Australia's arid-adapted butcherbirds experienced range expansions during Pleistocene glacial maxima

A model of range expansions during glacial maxima (GM) for cold-adapted species is generally accepted for the Northern Hemisphere. Given that GM in Australia largely resulted in the expansion of arid zones, rather than glaciation, it could be expected that arid-adapted species might have had expanded ranges at GM, as cold-adapted species did in the Northern Hemisphere. For Australian biota, however, it remains paradigmatic that arid-adapted species contracted to refugia at GM. Here we use multilocus data and ecological niche models (ENMs) to test alternative GM models for butcherbirds. ENMs, mtDNA and estimates of nuclear introgression and past population sizes support a model of GM expansion in the arid-tolerant Grey Butcherbird that resulted in secondary contact with its close relative - the savanna-inhabiting Silver-backed Butcherbird - whose contemporary distribution is widely separated. Together, these data reject the universal use of a GM contraction model for Australia's dry woodland and arid biota

All Hands on Deck: A Team Approach to System Migration

Purpose: To determine if a team approach to a complex integrated library system (ILS) migration would result in a timely and successful outcome. Brief Description: Changing needs and an aging integrated library system server platform prompted Himmelfarb Health Sciences Library to migrate to a new ILS. After considering several options, Himmelfarb decided to join with the George Washington University\u27s Jacob Burns Law Library in their move to a hosted instance of Innovative Interface\u27s Sierra ILS and Encore OPAC. Though some separation of data and functionality could be achieved, there were several functions that would be shared between the two libraries\u27 systems. A successful transition would depend upon both libraries\u27: detailed knowledge of the system data determining essential functionality to preserve willingness to change and accommodate Because the Law Library\u27s Sierra migration was delayed until mid-December 2012 and Himmelfarb\u27s pre-paid server maintenance was ending in March 2013, the window to accomplish migration was a short 12 weeks, prompting the decision to team-manage the migration. Conclusion: Teams and organizational tools, including weekly meetings to discuss problems, ensured the timely completion of key assignments that were critical to meeting the Go Live date goal. The team approach allowed the work and decision-making to be distributed among a large percentage of the staff, creating a broader sense of ownership. Distribution of tasks allowed a high level of attention to detail necessary for an optimal outcome

Dopaminergic manipulations affect the modulation and meta-modulation of movement speed:Evidence from two pharmacological interventions

A body of research implicates dopamine in the average speed of simple movements. However, naturalistic movements span a range of different shaped trajectories and rarely proceed at a single constant speed. Instead, speed is reduced when drawing “corners” compared to “straights” (i.e., speed modulation), and the extent of this slowing down is dependent upon the global shape of the movement trajectory (i.e., speed meta-modulation) – for example whether the shape is an ellipse or a rounded square. At present, it is not known how (or whether) dopaminergic function controls continuous changes in speed during movement execution. The current paper reports effects on these kinematic features of movement following two forms of dopamine manipulation: Study One highlights movement differences in individuals with PD both ON and OFF their dopaminergic medication (N = 32); Study Two highlights movement differences in individuals from the general population on haloperidol (a dopamine receptor blocker, or “antagonist”) and placebo (N = 43). Evidence is presented implicating dopamine in speed, speed modulation and speed meta-modulation, whereby low dopamine conditions are associated with reductions in these variables. These findings move beyond vigour models implicating dopamine in average movement speed, and towards a conceptualisation that involves the modulation of speed as a function of contextual information

Human Sulfatase 2 inhibits in vivo tumor growth of MDA-MB-231 human breast cancer xenografts

BACKGROUND: Extracellular human sulfatases modulate growth factor signaling by alteration of the heparin/heparan sulfate proteoglycan (HSPG) 6-O-sulfation state. HSPGs bind to numerous growth factor ligands including fibroblast growth factors (FGF), epidermal growth factors (EGF), and vascular endothelial growth factors (VEGF), and are critically important in the context of cancer cell growth, invasion, and metastasis. We hypothesized that sulfatase activity in the tumor microenvironment would regulate tumor growth in vivo. METHODS: We established a model of stable expression of sulfatases in the human breast cancer cell line MDA-MB-231 and purified recombinant human Sulfatase 2 (rhSulf2) for exogenous administration. In vitro studies were performed to measure effects on breast cancer cell invasion and proliferation, and groups were statistically compared using Student's t-test. The effects of hSulf2 on tumor progression were tested using in vivo xenografts with two methods. First, MDA-MB-231 cells stably expressing hSulf1, hSulf2, or both hSulf1/hSulf2 were grown as xenografts and the resulting tumor growth and vascularization was compared to controls. Secondly, wild type MDA-MB-231 xenografts were treated by short-term intratumoral injection with rhSulf2 or vehicle during tumor growth. Ultrasound analysis was also used to complement caliper measurement to monitor tumor growth. In vivo studies were statistically analyzed using Student's t test. RESULTS: In vitro, stable expression of hSulf2 or administration of rhSulf2 in breast cancer cells decreased cell proliferation and invasion, corresponding to an inhibition of ERK activation. Stable expression of the sulfatases in xenografts significantly suppressed tumor growth, with complete regression of tumors expressing both hSulf1 and hSulf2 and significantly smaller tumor volumes in groups expressing hSulf1 or hSulf2 compared to control xenografts. Despite significant suppression of tumor volume, sulfatases did not affect vascular density within the tumors. By contrast, transient exogenous treatment of MDA-MB-231 xenografts with rhSulf2 was not sufficient to inhibit or reverse tumor growth. CONCLUSION: These data indicate that in vivo progression of human breast cancer xenografts can be inhibited with sulfatase expression, and therapeutic effect requires constant delivery at the tumor site. Our results support a direct effect of sulfatases on tumor growth or invasion, rather than an effect in the stromal compartment

Androgen Receptor Inhibition Suppresses Anti-Tumor Neutrophil Response Against Bone Metastatic Prostate Cancer via Regulation of TβRI Expression

Bone metastatic disease of prostate cancer (PCa) is incurable and progression in bone is largely dictated by tumor-stromal interactions in the bone microenvironment. We showed previously that bone neutrophils initially inhibit bone metastatic PCa growth yet metastatic PCa becomes resistant to neutrophil response. Further, neutrophils isolated from tumor-bone lost their ability to suppress tumor growth through unknown mechanisms. With this study, our goal was to define the impact of metastatic PCa on neutrophil function throughout tumor progression and to determine the potential of neutrophils as predictive biomarkers of metastatic disease. Using patient peripheral blood polymorphonuclear neutrophils (PMNs), we identified that PCa progression dictates PMN cell surface markers and gene expression, but not cytotoxicity against PCa. Importantly, we also identified a novel phenomenon in which second generation androgen deprivation therapy (ADT) suppresses PMN cytotoxicity via increased transforming growth factor beta receptor I (TβRI). High dose testosterone and genetic or pharmacologic TβRI inhibition rescued androgen receptor-mediated neutrophil suppression and restored neutrophil anti-tumor immune response. These studies highlight the ability to leverage standard-care ADT to generate neutrophil anti-tumor responses against bone metastatic PCa

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200

Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers

We study frequency dependent (FD) input-output schemes for signal-recycling interferometers, the baseline design of Advanced LIGO and the current configuration of GEO 600. Complementary to a recent proposal by Harms et al. to use FD input squeezing and ordinary homodyne detection, we explore a scheme which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are sub-optimal among all possible input-output schemes, provide a global noise suppression by the power squeeze factor, while being realizable by using detuned Fabry-Perot cavities as input/output filters. At high frequencies, the two schemes are shown to be equivalent, while at low frequencies our scheme gives better performance than that of Harms et al., and is nearly fully optimal. We then study the sensitivity improvement achievable by these schemes in Advanced LIGO era (with 30-m filter cavities and current estimates of filter-mirror losses and thermal noise), for neutron star binary inspirals, and for narrowband GW sources such as low-mass X-ray binaries and known radio pulsars. Optical losses are shown to be a major obstacle for the actual implementation of these techniques in Advanced LIGO. On time scales of third-generation interferometers, like EURO/LIGO-III (~2012), with kilometer-scale filter cavities, a signal-recycling interferometer with the FD readout scheme explored in this paper can have performances comparable to existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi

Search for gravitational wave bursts in LIGO's third science run

We report on a search for gravitational wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets subsecond bursts in the frequency range 100-1100 Hz for which no waveform model is assumed, and has a sensitivity in terms of the root-sum-square (rss) strain amplitude of hrss ~ 10^{-20} / sqrt(Hz). No gravitational wave signals were detected in the 8 days of analyzed data.Comment: 12 pages, 6 figures. Amaldi-6 conference proceedings to be published in Classical and Quantum Gravit

Mice Deficient in T-bet Form Inducible NO Synthase-Positive Granulomas That Fail to Constrain Salmonella.

Clearance of intracellular infections caused by Salmonella Typhimurium (STm) requires IFN-γ and the Th1-associated transcription factor T-bet. Nevertheless, whereas IFN-γ-/- mice succumb rapidly to STm infections, T-bet-/- mice do not. In this study, we assess the anatomy of immune responses and the relationship with bacterial localization in the spleens and livers of STm-infected IFN-γ-/- and T-bet-/- mice. In IFN-γ-/- mice, there is deficient granuloma formation and inducible NO synthase (iNOS) induction, increased dissemination of bacteria throughout the organs, and rapid death. The provision of a source of IFN-γ reverses this, coincident with subsequent granuloma formation and substantially extends survival when compared with mice deficient in all sources of IFN-γ. T-bet-/- mice induce significant levels of IFN-γ- after challenge. Moreover, T-bet-/- mice have augmented IL-17 and neutrophil numbers, and neutralizing IL-17 reduces the neutrophilia but does not affect numbers of bacteria detected. Surprisingly, T-bet-/- mice exhibit surprisingly wild-type-like immune cell organization postinfection, including extensive iNOS+ granuloma formation. In wild-type mice, most bacteria are within iNOS+ granulomas, but in T-bet-/- mice, most bacteria are outside these sites. Therefore, Th1 cells act to restrict bacteria within IFN-γ-dependent iNOS+ granulomas and prevent dissemination