Plant composition of three woodland communities of variable condition in the western Riverina, New South Wales, Australia

We examined differences in floristics among three regionally-threatened woodland communities in the western Riverina: Blackbox (Eucalyptus largiflorens), Bimble box-Pine (Eucalyptus populnea-Callitris glaucophylla) and Boree (Acacia pendula) between 2001 and 2004. Our aim was to examine possible relationships between the diversity and biomass of groundstorey vegetation, and remnant condition and rainfall both among communities and across years. The three woodland communities varied widely in their plant species composition, with only 22% of the 358 species common to all communities. Seven species, mainly exotic grasses and forbs, contributed 25% of the total cover across all sites and times. Blackbox communities had the greatest number of exotic and annual species. There were poor relationships between condition and diversity, richness, evenness or abundance of groundstorey plant species within 400 m2 quadrats. Overall, sites in better condition tended to support a greater cover of native plants and a lower cover of exotic plants (Blackbox only). There were only weak relationships between rainfall and biomass. The marked variation in species diversity in relation to changing seasonal conditions and within similar condition classes highlights the difficulties of developing benchmarks for separating the effects of management, and seasonal and longer-term climate change

Capital Structure and Political Risk in Asia-Pacific Real Estate Markets

This study investigates the determinants of capital structure decisions by real estate firms, with a specific focus on the impact of political risk on leverage. Using a sample of Asia-Pacific REITs and listed property trusts, we find those firms with properties located in countries characterized by relatively high degrees of political risk, such as political instability, and/or greater uncertainty in the ability to repatriate and monetize profits from international investment activities, employ less debt than their counterparts operating in more politically stable environments. This core finding remains robust to alternative sample selection criteria including the division of the sample into high versus low market-to-book value firms, and also holds within the subset of organizations that are active in raising additional capital in the secondary markets

Advisor Choice in Asia-Pacific Property Markets

This paper examines advisor choice decisions by publicly traded REITs and listed property companies in Asia-Pacific real estate markets. Using a sample of 168 firms, we find robust evidence that firms strategically evaluate and compare the increased agency costs associated with external advisement against the potential benefits associated with collocating decision rights with location specific soft information. Our empirical results reveal real estate companies tend to hire external advisors when they invest in countries: 1) that are more economically and politically unstable, 2) whose legal system is based on civil law, 3) where the level of corruption is perceived to be high, and 4) when disclosure is relatively poor. Additionally, we find the probability of retaining an external advisor is directly related to the expected agency costs. Lastly, we find evidence of return premiums in excess of 13 % for firms whose organizational structure matches their investment profile. As such, we conclude that the decision to hire an external advisor represents a value relevant trade-off between the costs and benefits of this organizational arrangement

Independent regulation of P53 stabilisation and activation after Rb deletion in primary epithelial cells

We have previously reported that deletion of the retinoblastoma gene Rb leads to rapid but transient p53 stabilisation. We investigated here the pathways involved. We show that upon Rb-deletion dysregulated E2F activates p19(ARF) expression that localises in the nucleoli. There it interacts with MDM2, leading to P53 stabilisation. At the same time, ATR is activated, activating CHK1 that may phosphorylate P53 but also contribute to inhibition of MnSOD expression leading to accumulation of ROS (reactive oxygen species) and subsequent DNA injury, which in turn maintains ATR/CHK1 activated. However, from 72 h after Rb deletion, NPM interacts with P19ARF and concomitantly the interaction between p19(ARF) and MDM2 decreases leading to a return to P53 degradation. This occurs despite the persistence of the DNA damage response pathways. We therefore observe in primary cells not subjected to exogenous gene expression or exogenous DNA damaging treatment, activation of 2 concomitant pathways of activation of P53 that are dealt with in independent manner: an oncogenic pathway with rapid activation of ARF which is 'switched off' downstream of p19(ARF) activation after 72 h of induction and a DNA damage response pathway keeping a low level of transcriptionally active P53 sufficient to deal with a physiological elevation of oxidative DNA injury. A possible connection between the two pathways is discussed.Publisher PDFPeer reviewe

Studies of the diagnosis and immunopathogenesis of Wegener's granulomatosis

Wegener's Granulomatosis, classically, comprises a triad of granulomatous vasculitis in the upper and lower respiratory tracts, and a focal and segmental, necrotising glomerulonephritis in the kidney. In practice disease presentation and organ involvement is widespread and variable. The aetiology is unknown but an infectious aetiology has been proposed, based on the especial involvement of the respiratory tract in the disease process. The pathogenesis is also unclear but immune complex deposition leading to neutrophil chemotaxis and activation causing endothelial injury has been suggested. Recently antibodies against a component of neutrophil cytoplasm have been described in Wegener's Granulomatosis. This thesis records studies of the diagnosis and pathogenesis of Wegener's Granulomatosis. The first part of the study examined the problem of diagnosis using renal biopsy material. Renal biopsy is important because renal functional status is the major factor determining outcome, yet renal biopsy appearances are not specific for the condition and may be found in other vasculitides such as microscopic polyarteritis. Review of the histology, immunofluorescence studies and ultrastructure of renal biopsies from patients with Wegener's Granulomatosis and microscopic polyarteritis revealed no diagnostically useful differences. In Wegener's Granulomatosis renal mast cells were frequently present unassociated with areas of active inflammation, whereas in microscopic polyarteritis they were predominantly present as part of an inflammatory infiltrate. In both conditions the number of mast cells was increased. The functional significance of this difference is unclear.The second part of the study examined the presence of autoantibodies against neutrophils. IgG antibodies giving coarse, granular, cytoplasmic fluorescence when incubated with cytospin preparations of normal neutrophils were found to be highly specific for Wegener's Granulomatosis. Diffuse cytoplasmic fluorescence was present in a wide variety of other diseases including some other forms of systemic vasculitis. By differential protein extraction of neutrophils and Western Blot analysis IgG antibodies which gave coarse fluorescence were found to react with 4 5 kDa and 27-31 kDa proteins in the membrane-bound protein extract. This is consistent with the autoantibodies being directed against a component of neutrophil granules.An hypothesis is proposed. Wegener's Granulomatosis is the product of an immunological response to an antigen, possibly to an inhaled, exogenous pathogen. A predominantly cell-mediated response results in the typical lesions identified pathologically within the respiratory tract including granulomata. A humoral response also may ii occur, reflected by the presence of specific autoantibodies and this can lead to systemic injury primarily by the formation and deposition of immune complexes. In other systemic vasculitides, such as microscopic polyarteritis, a variety of exogenous antigens result in humoral responses and immune complex formation and deposition leading to the same pattern of renal injury

Zapotec Language Activism And Talking Dictionaries

Online dictionaries have become a key tool for some indigenous communities to promote and preserve their languages, often in collaboration with linguists. They can provide a pathway for crossing the digital divide and for establishing a first-ever presence on the internet. Many questions around digital lexicography have been explored, although primarily in relation to large and well-resourced languages. Lexical projects on small and under-resourced languages can provide an opportunity to examine these questions from a different perspective and to raise new questions (Mosel, 2011). In this paper, linguists, technical experts, and Zapotec language activists, who have worked together in Mexico and the United States to create a multimedia platform to showcase and preserve lexical, cultural, and environmental knowledge, share their experience and insight in creating trilingual online Talking Dictionaries in several Zapotec languages. These dictionaries sit opposite from big data mining and illustrate the value of dictionary projects based on small corpora, including having the flexibility to make design decisions to maximize community impact and elevate the status of marginalized languages

The Impact of Geographic and Cultural Dispersion on Information Opacity

This paper investigates the influences of intrafirm geographic and cultural dispersion, the distance between the location of a firm’s investments and its headquarters, on the firm’s information environment. Specifically, using a sample of publicly traded real estate companies across the Asia-Pacific region, we examine how intrafirm geographic and cultural distance impacts a firm’s capital acquisition costs. As a consequence of both the heavily regulated operating environment faced by these firms, as well as the capital intensive nature of this industry, funding costs should be of pronounced importance to firms within this sector. Consistent with this paradigm, we find that firms with geographically disperse investments exhibit enhanced informational opacity. Specifically, firms with more geographically disperse investments exhibit higher capital acquisition costs than their more geographically concentrated counterparts. Similarly, firms with more culturally disparate investments also exhibit enhanced informational opacity, as evidenced by increased capital costs. Additionally, we present evidence that the impact of both physical and cultural distance is increasing following the global financial crisis. Taken together, our results provide strong evidence that both intrafirm geographic and cultural dispersion materially impact both an organization’s information environment and funding costs

Parallel compensatory evolution stabilizes plasmids across the parasitism-mutualism continuum

Plasmids drive genomic diversity in bacteria via horizontal gene transfer [1 and 2]; nevertheless, explaining their survival in bacterial populations is challenging [3]. Theory predicts that irrespective of their net fitness effects, plasmids should be lost: when parasitic (costs outweigh benefits), plasmids should decline due to purifying selection [4, 5 and 6], yet under mutualism (benefits outweigh costs), selection favors the capture of beneficial accessory genes by the chromosome and loss of the costly plasmid backbone [4]. While compensatory evolution can enhance plasmid stability within populations [7, 8, 9, 10, 11, 12, 13, 14 and 15], the propensity for this to occur across the parasitism-mutualism continuum is unknown. We experimentally evolved Pseudomonas fluorescens and its mercury resistance mega-plasmid, pQBR103 [ 16], across an environment-mediated parasitism-mutualism continuum. Compensatory evolution stabilized plasmids by rapidly ameliorating the cost of plasmid carriage in all environments. Genomic analysis revealed that, in both parasitic and mutualistic treatments, evolution repeatedly targeted the gacA/gacS bacterial two-component global regulatory system while leaving the plasmid sequence intact. Deletion of either gacA or gacS was sufficient to completely ameliorate the cost of plasmid carriage. Mutation of gacA/gacS downregulated the expression of ∼17% of chromosomal and plasmid genes and appears to have relieved the translational demand imposed by the plasmid. Chromosomal capture of mercury resistance accompanied by plasmid loss occurred throughout the experiment but very rarely invaded to high frequency, suggesting that rapid compensatory evolution can limit this process. Compensatory evolution can explain the widespread occurrence of plasmids and allows bacteria to retain horizontally acquired plasmids even in environments where their accessory genes are not immediately useful

A model of estrogen-related gene expression reveals non-linear effects in transcriptional response to tamoxifen

SynthSys is a Centre for Integrative Systems Biology (CISB) funded by BBSRC and EPSRC, reference BB/D019621/1.Background: Estrogen receptors alpha (ER) are implicated in many types of female cancers, and are the common target for anti-cancer therapy using selective estrogen receptor modulators (SERMs, such as tamoxifen). However, cell-type specific and patient-to-patient variability in response to SERMs (from suppression to stimulation of cancer growth), as well as frequent emergence of drug resistance, represents a serious problem. The molecular processes behind mixed effects of SERMs remain poorly understood, and this strongly motivates application of systems approaches. In this work, we aimed to establish a mathematical model of ER-dependent gene expression to explore potential mechanisms underlying the variable actions of SERMs. Results: We developed an equilibrium model of ER binding with 17 beta-estradiol, tamoxifen and DNA, and linked it to a simple ODE model of ER-induced gene expression. The model was parameterised on the broad range of literature available experimental data, and provided a plausible mechanistic explanation for the dual agonism/antagonism action of tamoxifen in the reference cell line used for model calibration. To extend our conclusions to other cell types we ran global sensitivity analysis and explored model behaviour in the wide range of biologically plausible parameter values, including those found in cancer cells. Our findings suggest that transcriptional response to tamoxifen is controlled in a complex non-linear way by several key parameters, including ER expression level, hormone concentration, amount of ER-responsive genes and the capacity of ER-tamoxifen complexes to stimulate transcription (e. g. by recruiting co-regulators of transcription). The model revealed non-monotonic dependence of ER-induced transcriptional response on the expression level of ER, that was confirmed experimentally in four variants of the MCF-7 breast cancer cell line. Conclusions: We established a minimal mechanistic model of ER-dependent gene expression, that predicts complex non-linear effects in transcriptional response to tamoxifen in the broad range of biologically plausible parameter values. Our findings suggest that the outcome of a SERM's action is defined by several key components of cellular micro-environment, that may contribute to cell-type-specific effects of SERMs and justify the need for the development of combinatorial biomarkers for more accurate prediction of the efficacy of SERMs in specific cell types.Publisher PDFPeer reviewe

Integrin characterization in pulmonary bronchioles

Integrins are a family of cell surface glycoproteins that act as receptors for ECM proteins or for membrane bound counter-receptors on other cells. The integrin receptor family of vertebrates includes at least 16 distinct α subunits and at least 8 β subunits which can associate to form more than 20 distinct integrins. So far, there are no published reports describing integrin characterization in mouse lung tissue and mouse Clara cells. This paper described the characterization of six integrins, mainly α5, αv, α6, β1, β3, and β4, in mouse pulmonary bronchioles and also in Clara cell cultures. α5, αv, α6, β1, and β4 integrins were present in Clara cells both in tissue sections and cultures. β3 integrin was found to be absent in mouse Clara cells.peer-reviewe