The impact of Phytophthora cinnamomi on the distribution of the yellow-footed antechinus (mardo) (Antechinus flavipes leucogaster) (Marsupialia: Dasyuridae)

This is the first study to investigate and provide definitive evidence that the plant pathogen Phytophthora cinnamomi is a significant threat to the mammal fauna of Western Australia. This study investigated the impact of P. cinnamomi-induced habitat disturbance and degradation on Antechinus flavipes leucogaster (yellow-footed antechinus) or mardo. Phytophthora cinnamomi is an introduced and invasive soil-borne plant pathogen that kills many common and structurally important plant species, which results in significant changes to the structural characteristics of affected areas. An evaluation of P. cinnamomi affected and unaffected areas of the northern jarrah (Eucalyptus marginata) forest revealed significant declines in the structure, composition and complexity of all areas affected by P. cinnamomi. Dieback Expression Score values ranged from a mean value of 1.88 ± 1.01 to 3.8 ± 0.41 at the P. cinnamomi affected sites, indicating a high degree of disturbance. A non-metric multidimensional scaling (MDS) analysis using 16 habitat variables identified significant (ANISOM: R=0.343, P<0.003) separation among affected and unaffected sites. A SIMPER analysis revealed that ground and shrub cover vegetation, small and total log densities, percentage leaf litter cover, and the densities of small, medium, tall single crowned and total Xanthorrhoea preissii were the greatest contributors separating affected and unaffected areas. Presently, our understanding of how P. cinnamomi affects the fauna of Western Australia is limited. This providing a unique opportunity to examine how P. cinnamomi-induced disturbance impacts upon the mardo. The mardo is a small insectivorous marsupial that is regarded as being common and a habitat generalist that occupies a broad range of forest and woodland habitats throughout the south-west of Western Australia. Until the present study, the specific habitat requirements, and therefore the factors limiting the present distribution of the mardo have received little attention. Therefore, in addition to being the first study to evaluate the impact of P. cinnamomi on Western Australian fauna, this study also provides important information about the present distribution of the mardo. Detection-nondetection mark-release surveys conducted in P. cinnamomi affected and unaffected regions of the northern jarrah forest, revealed that although, mardos were recorded at most sites, the number of mardo individuals, captures and detections were considerably lower at P. cinnamomi affected areas. Patch Occupancy analysis, using an information theoretic approach, revealed that the probability of a mardo occupying a region of the northern jarrah forest affected by P. cinnamomi ranged from a likelihood of 0.0 to 25.0%, while in contrast there was a 41.0 to 51.0% likelihood of a mardo occurring among unaffected regions. This discovery supports the hypothesis that P. cinnamomi-induced habitat disturbance impacts upon the distribution of the mardo. An evaluation of the micro-habitat features important to the mardo using Patch Occupancy modelling using an information theoretic approach identified large logs and X. preissii densities as positive contributors to the present distribution of the mardo in the northern jarrah forest. Indeed, the likelihood of a mardo occupying an area with large logs and dense patches of X. preissii ranged from 62.2% to 85.0%. In contrast, in the P. cinnamomi affected sites with lower X. preissii densities the patch occupancy probabilities ranged from 0.0% to 45.7%. Logs and X. preissii strongly contribute to the understorey and may increase nest locations and cover while offering protection from predators. Mardos may avoid P. cinnamomi affected areas because of lower X. preissii densities, which may result in fewer nest locations, reduced cover and an increased likelihood of predation. However, the results of the study must be treated as preliminary findings, therefore there may be additional environmental related or unrelated to P. cinnamomi factors that may also contribute to the occupancy rates of the mardo. Therefore, further studies and research on the ecology and biology of the mardo is strongly encouraged. Until this research is conducted, P. cinnamomi most be considered as significant threat to the conservation of the mardo. Therefore, the conservation of the mardo in the northern jarrah forest depends on limiting the spread and impact of P. cinnamomi, as well as the retention of large logs and tall X. preissii. Given that large logs and tall X. preissii contribute to the distribution of the mardo, strong consideration must be given to using these natural elements to rehabilitate the most severely disturbed areas of the northern jarrah forest. Consideration must be given to the conservation of other small and threatened mammal species that inhabit susceptible plant communities in the south-west of Western Australia. An understanding of how P. cinnamomi impacts on the mardo and other native mammals will contribute to our ability to control, protect and manage vulnerable communities and ecosystems in Western Australia. If the spread and impact of this pathogen is left unchecked, the ultimate consequence to the conservation of many small to medium native mammals that are dependant on structurally complex habitat may be devastating

Aerosol pH and liquid water content determine when particulate matter is sensitive to ammonia and nitrate availability

Nitrogen oxides (NOx) and ammonia (NH3) from anthropogenic and biogenic emissions are central contributors to particulate matter (PM) concentrations worldwide. The response of PM to changes in the emissions of both compounds is typically studied on a case-by-case basis, owing in part to the complex thermodynamic interactions of these aerosol precursors with other PM constituents. Here we present a simple but thermodynamically consistent approach that expresses the chemical domains of sensitivity of aerosol particulate matter to NH3 and HNO3 availability in terms of aerosol pH and liquid water content. From our analysis, four policy-relevant regimes emerge in terms of sensitivity: (i) NH3 sensitive, (ii) HNO3 sensitive, (iii) NH3 and HNO3 sensitive, and (iv) insensitive to NH3 or HNO3. For all regimes, the PM remains sensitive to nonvolatile precursors, such as nonvolatile cations and sulfate. When this framework is applied to ambient measurements or predictions of PM and gaseous precursors, the “chemical regime” of PM sensitivity to NH3 and HNO3 availability is directly determined. The use of these regimes allows for novel insights, and this framework is an important tool to evaluate chemical transport models. With this extended understanding, aerosol pH and associated liquid water content naturally emerge as previously ignored state parameters that drive PM formation

Plant pathogens causing vegetation dieback: a serious threat to the conservation of small mammals in Australia

The soil-borne plant pathogen Phytophthora cinnamomi occurs in most Australian states. It is pathogenic to many Australian species, particularly the Proteaceae, Fabaceae, Dillineaceae and Epacridaceae. In Western Australia, c. 2000 of the 9000 endemic plant species are directly affected by the disease. The epidemic of plant deaths caused by P. cinnamomi is recognised as one of 11 Key Threatening Processes to the Australian Environment, and is now also acknowledged as a potential threat fauna in a range of communities. The implications of landscape modification due to the effects of P. cinnamomi dieback prompted our research, designed to measure the distribution and abundance of small mammals in disease-affected ecosystems. This study was in the Jarrah (Eucalyptus marginata) forests in the Darling Range, Western Australia and measured the distribution and abundance of one small mammal species, the Mardo (Antechinus flavipes) by Elliott trapping in forests with (1) high, (2) mixed and (3) no evidence of Phytophthora dieback. Trap success was highest in sites with no effect of Phytophthora (7.3 animals per 100 trap nights), whereas the lowest trap success was recorded at the high impact sites (0.67 animals per 100 trap night). There was a significant difference in trap success of Mardos in Elliott trapping over 1800 trap nights (x2= 23.19, d.f = 5, p &lt; 0.001). An examination of the distribution of individuals and sexes suggests that Phytophthora-affected sites act as sinks for Mardos, while source areas are healthy, unaffected Jarrah forest.<br /

Revising the use of potassium (K) in the source apportionment of PM\u3csub\u3e2.5\u3c/sub\u3e

Elemental potassium has been extensively used as an indicator of biomass burning in the source apportionment of PM . We present a method to estimate the fraction of potassium associated with biomass burning (K ) based on a linear regression with iron that can be applied at any site where PM chemical speciation is available. The estimated fraction has a significantly greater correlation with levoglucosan (R =0.63), an organic tracer of biomass burning, than total potassium (R =0.39). We explore temporal and spatial variability of K over a period of six years in the Atlanta area. K is larger in spring when biomass burning activity is more prevalent and during weekends due to the use of fireplaces in winter and outdoor charcoal cooking in summer. K is the predominate form of potassium for the rural site in this study. The use of K in a receptor model results in a lower fraction of PM apportioned to biomass burning and a greater fraction to mobile sources when compared to the use of total K. Results suggest that K is a good indicator of biomass burning. © Author(s) 2012. 2.5 b 2.5 b b b b 2.5 b 2

Revising the use of potassium (K) in the source apportionment of PM2.5

AbstractElemental potassium has been extensively used as an indicator of biomass burning in the source apportionment of PM2.5. We present a method to estimate the fraction of potassium associated with biomass burning (Kb) based on a linear regression with iron that can be applied at any site where PM2.5 chemical speciation is available. The estimated fraction has a significantly greater correlation with levoglucosan (R2=0.63), an organic tracer of biomass burning, than total potassium (R2=0.39). We explore temporal and spatial variability of Kb over a period of six years in the Atlanta area. Kb is larger in spring when biomass burning activity is more prevalent and during weekends due to the use of fireplaces in winter and outdoor charcoal cooking in summer. Kb is the predominate form of potassium for the rural site in this study. The use of Kb in a receptor model results in a lower fraction of PM2.5 apportioned to biomass burning and a greater fraction to mobile sources when compared to the use of total K. Results suggest that Kb is a good indicator of biomass burning

MicroRNA Expression Profiling in HCV-Infected Human Hepatoma Cells Identifies Potential Anti-Viral Targets Induced by Interferon-α

<div><h3>Objective</h3><p>Increasing evidence suggests that miRNAs have a profound impact on host defense to Hepatitis C virus (HCV) infection and clinical outcome of standard HCV therapy. In this study, we investigated modulation of miRNA expression in Huh7.5 hepatoma cells by HCV infection and <em>in vitro</em> interferon-αtreatment.</p> <h3>Methods</h3><p>MiRNA expression profiling was determined using Human miRNA TaqMan® Arrays followed by rigorous pairwise statistical analysis. MiRNA inhibitors assessed the functional effects of miRNAs on HCV replication. Computational analysis predicted anti-correlated mRNA targets and their involvement in host cellular pathways. Quantitative RTPCR confirmed the expression of predicted miRNA-mRNA correlated pairs in HCV-infected Huh7.5 cells with and without interferon-α.</p> <h3>Results</h3><p>Seven miRNAs (miR-30b, miR-30c, miR-130a, miR-192, miR-301, miR-324-5p, and miR-565) were down-regulated in HCV-infected Huh7.5 cells (p<0.05) and subsequently up-regulated following interferon-α treatment (p<0.01). The miR-30(a-d) cluster and miR-130a/301 and their putative mRNA targets were predicted to be associated with cellular pathways that involve Hepatitis C virus entry, propagation and host response to viral infection.</p> <h3>Conclusions</h3><p>HCV differentially modulates miRNAs to facilitate entry and early establishment of infection <em>in vitro</em>. Interferon-α appears to neutralize the effect of HCV replication on miRNA regulation thus providing a potential mechanism of action in eradicating HCV from hepatocytes.</p> </div

Comparison of SOC estimates and uncertainties from aerosol chemical composition and gas phase data in Atlanta

In the Southeastern US, organic carbon (OC) comprises about 30% of the PM mass. A large fraction of OC is estimated to be of secondary origin. Long-term estimates of SOC and uncertainties are necessary in the evaluation of air quality policy effectiveness and epidemiologic studies. Four methods to estimate secondary organic carbon (SOC) and respective uncertainties are compared utilizing PM chemical composition and gas phase data available in Atlanta from 1999 to 2007. The elemental carbon (EC) tracer and the regression methods, which rely on the use of tracer species of primary and secondary OC formation, provided intermediate estimates of SOC as 30% of OC. The other two methods, chemical mass balance (CMB) and positive matrix factorization (PMF) solve mass balance equations to estimate primary and secondary fractions based on source profiles and statistically-derived common factors, respectively. CMB had the highest estimate of SOC (46% of OC) while PMF led to the lowest (26% of OC). The comparison of SOC uncertainties, estimated based on propagation of errors, led to the regression method having the lowest uncertainty among the four methods. We compared the estimates with the water soluble fraction of the OC, which has been suggested as a surrogate of SOC when biomass burning is negligible, and found a similar trend with SOC estimates from the regression method. The regression method also showed the strongest correlation with daily SOC estimates from CMB using molecular markers. The regression method shows advantages over the other methods in the calculation of a long-term series of SOC estimates. © 2010 Elsevier Ltd. 2.5 2.

Location of putative miR-30c binding sites in the 3′ UTR of target mRNAs.

<p>P_CT – Probability of conserved targeting (Friedman, 2009).</p

Location of putative miR-130a binding sites in the 3′ UTR of target mRNAs.

<p>P_CT – Probability of conserved targeting <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055733#pone.0055733-Friedman1" target="_blank">[23]</a>.</p

Expression of mRNA targets of miR-130a/301 in HCV-infected Huh7.5 treated with IFN-α.

<p>The top seven highly predicted mRNAs of gene targets for miR-130a/301 found in the endocytosis pathway (A) and TGF-β signaling pathways (B) were tested for expression using real-time quantitative RT-PCR and HCV-infected Huh7.5 cells without IFN-α (HCV effect) and with IFN-α (HCV+ IFN effect). The fold change in gene expression is normalized to GAPDH.</p