Wheat archive links long-term fungal pathogen population dynamics to air pollution

We used the PCR to study the presence of two plant pathogens in archived wheat samples from a long-term experiment started in 1843. The data were used to construct a unique 160-yr time-series of the abundance of Phaeosphaeria nodorum and Mycosphaerella graminicola, two important pathogens of wheat. During the period since 1970, the relative abundance of DNA of these two pathogens in the samples has reflected the relative importance of the two wheat diseases they cause in U.K. disease surveys. Unexpectedly, changes in the ratio of the pathogens over the 160-yr period were very strongly correlated with changes in atmospheric pollution, as measured by SO2 emissions. This finding suggests that long-term, economically important, changes in pathogen populations can be influenced by anthropogenically induced environmental changes.&nbsp

A Connection between Colony Biomass and Death in Caribbean Reef-Building Corals

Increased sea-surface temperatures linked to warming climate threaten coral reef ecosystems globally. To better understand how corals and their endosymbiotic dinoflagellates (Symbiodinium spp.) respond to environmental change, tissue biomass and Symbiodinium density of seven coral species were measured on various reefs approximately every four months for up to thirteen years in the Upper Florida Keys, United States (1994–2007), eleven years in the Exuma Cays, Bahamas (1995–2006), and four years in Puerto Morelos, Mexico (2003–2007). For six out of seven coral species, tissue biomass correlated with Symbiodinium density. Within a particular coral species, tissue biomasses and Symbiodinium densities varied regionally according to the following trends: Mexico≥Florida Keys≥Bahamas. Average tissue biomasses and symbiont cell densities were generally higher in shallow habitats (1–4 m) compared to deeper-dwelling conspecifics (12–15 m). Most colonies that were sampled displayed seasonal fluctuations in biomass and endosymbiont density related to annual temperature variations. During the bleaching episodes of 1998 and 2005, five out of seven species that were exposed to unusually high temperatures exhibited significant decreases in symbiotic algae that, in certain cases, preceded further decreases in tissue biomass. Following bleaching, Montastraea spp. colonies with low relative biomass levels died, whereas colonies with higher biomass levels survived. Bleaching- or disease-associated mortality was also observed in Acropora cervicornis colonies; compared to A. palmata, all A. cervicornis colonies experienced low biomass values. Such patterns suggest that Montastraea spp. and possibly other coral species with relatively low biomass experience increased susceptibility to death following bleaching or other stressors than do conspecifics with higher tissue biomass levels

Genetic basis of control of Rhynchosporium secalis infection and symptom expression in barley

The genetic basis of several different components of resistance to Rhynchosporium secalis in barley was investigated in a mapping population derived from a cross between winter and spring barley types. Both the severity of visual disease symptoms and amount of R. secalis DNA in leaf tissues were assessed in field trials in Scotland in the 2007/2008 and 2008/2009 growing seasons. Relative expression of symptoms was defined as the residual values from a linear regression of amount of R. secalis DNA against visual plot disease score at GS 50. Amount of R. secalis DNA and visual disease score were highly correlated traits and identified nearly identical QTL. The genetic control of relative expression of symptoms was less clear. However, a QTL on chromosome 7H was identified as having a significant effect on the expression of visual disease symptoms relative to overall amount of R. secalis colonisationPeer reviewedFinal Accepted Versio

The SECURE project – Stem canker of oilseed rape: : molecular methods and mathematical modelling to deploy durable resistance

N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and mathematical modeling to deploy durable resistance", in Vol 4 of the Proceedings of the 12th International Rapeseed Congress : Sustainable Development in Cruciferous Oilseed Crops Production, Wuhan, China, March 26 - 30, 2007. The proceedings are available online at: http://gcirc.org/intranet/irc-proceedings/12th-irc-wuhan-china-2007-vol-4.htmlModelling done during the SECURE project has demonstrated the dynamic nature of the interaction between phoma stem canker (Leptosphaeria maculans), the oilseed rape host (Brassica napus) and the environment. Experiments done with near-isogenic lines of L. maculans to investigate pathogen fitness support field data that suggest a positive effect of the avirulence allele AvrLm4 on pathogen fitness, and that the loss of this allele renders isolates less competitive under field conditions on cultivars without the resistance gene Rlm4. The highlight of molecular work was the cloning of AvrLm1 and AvrLm6. L. maculans is now one of the few fungal species for which two avirulence loci have been cloned. Subsequent research focused on understanding the function of AvrLm1 and AvrLm6 and on the analysis of sequences of virulent isolates to understand molecular evolution towards virulence. Isolates of L. maculans transformed with GFP and/or DsRed were used to follow growth of the fungus in B. napus near-isogenic-lines (NIL) with or without MX (Rlm6) resistance under different temperature and wetness conditions. The results greatly enhanced our knowledge of the infection process and the rate and extent of in planta growth on different cultivars. Conclusions from work to model durability of resistance have been tested under field conditions through a series of experiments to compare durability of resistance conferred by the major resistance gene Rlm6 alone in a susceptible background (EurolMX) or in a resistant background (DarmorMX) under recurrent selection over 4 growing seasons. A major priority of the project was knowledge transfer of results and recommendations to target audiences such as plant breeding companies and extension services. CETIOM developed a “diversification scheme” that encourages French growers to make an informed choice about the cultivars that are grown within the rotation based on the resistance genes carried by the individual cultivars. Use of such schemes, in association with survey data on the population structure of L. maculans at both national and European scales will provide opportunities for breeders and the industry to manage available B. napus resistance more effectively.Non peer reviewe

Hypermagnetic Knots, Chern-Simons Waves and the Baryon Asymmetry

At finite hyperconductivity and finite fermionic density the flux lines of long range hypermagnetic fields may not have a topologically trivial structure. The combined evolution of the chemical potentials and of pseudoscalar fields (like the axial Higgs), possibly present for temperatures in the TeV range, can twist the hypercharge flux lines, producing, ultimately, hypermagnetic knots (HK). The dynamical features of the HK depend upon the various particle physics parameters of the model (pseudoscalar masses and couplings, strength of the electroweak phase transition, hyperconductivity of the plasma) and upon the magnitude of the primordial flux sitting in topologically trivial configurations of the hypermagnetic field. We study different cosmological scenarios where HK can be generated. We argue that the fermionic number sitting in HK can be released producing a seed for the Baryon Asymmetry of the Universe (BAU) provided the typical scale of the knot is larger than the diffusivity length scale. We derive constraints on the primordial hypermagnetic flux required by our mechanism and we provide a measure of the parity breaking by connecting the degree of knottedness of the flux lines to the BAU. We rule out the ordinary axion as a possible candidate for production (around temperatures of the order of the GeV) of {\em magnetic} knots since the produced {\em electromagnetic} helicity is negligible (for cosmological standard) if the initial amplitude of the axion oscillations is of the order of the Peccei-Quinn breaking scale.Comment: 30 pages in Revtex style, 8 figure

Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.

BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials. METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ≥50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), P = 0.02] and carotid endarterectomy [2.43 (1.03-5.73), P = 0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), P = 0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface. CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials

Impacts of climate change on plant diseases – opinions and trends

There has been a remarkable scientific output on the topic of how climate change is likely to affect plant diseases in the coming decades. This review addresses the need for review of this burgeoning literature by summarizing opinions of previous reviews and trends in recent studies on the impacts of climate change on plant health. Sudden Oak Death is used as an introductory case study: Californian forests could become even more susceptible to this emerging plant disease, if spring precipitations will be accompanied by warmer temperatures, although climate shifts may also affect the current synchronicity between host cambium activity and pathogen colonization rate. A summary of observed and predicted climate changes, as well as of direct effects of climate change on pathosystems, is provided. Prediction and management of climate change effects on plant health are complicated by indirect effects and the interactions with global change drivers. Uncertainty in models of plant disease development under climate change calls for a diversity of management strategies, from more participatory approaches to interdisciplinary science. Involvement of stakeholders and scientists from outside plant pathology shows the importance of trade-offs, for example in the land-sharing vs. sparing debate. Further research is needed on climate change and plant health in mountain, boreal, Mediterranean and tropical regions, with multiple climate change factors and scenarios (including our responses to it, e.g. the assisted migration of plants), in relation to endophytes, viruses and mycorrhiza, using long-term and large-scale datasets and considering various plant disease control methods

An Initial Look at the Far Infrared-Radio Correlation within Nearby Star-forming Galaxies using the Spitzer Space Telescope

(Abridged) We present an initial look at the far infrared-radio correlation within the star-forming disks of four nearby, nearly face-on galaxies (NGC 2403, NGC 3031, NGC 5194, and NGC 6946). Using Spitzer MIPS imaging and WSRT radio continuum data, observed as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS), we are able to probe variations in the logarithmic 24mu/22cm (q_24) and 70mu/22cm (q_70) surface brightness ratios across each disk at sub-kpc scales. We find general trends of decreasing q_24 and q_70 with declining surface brightness and with increasing radius. The residual dispersion around the trend of q_24 and q_70 versus surface brightness is smaller than the residual dispersion around the trend of q_24 and q_70 versus radius, on average by ~0.1 dex, indicating that the distribution of star formation sites is more important in determining the infrared/radio disk appearance than the exponential profiles of disks. We have also performed preliminary phenomenological modeling of cosmic ray electron (CRe^-) diffusion using an image-smearing technique, and find that smoothing the infrared maps improves their correlation with the radio maps. Exponential kernels tend to work better than Gaussian kernels which suggests that additional processes besides simple random-walk diffusion in three dimensions must affect the evolution of CRe^-s. The best fit smoothing kernels for the two less active star-forming galaxies (NGC 2403 and NGC 3031) have much larger scale-lengths than those of the more active star-forming galaxies (NGC 5194 and NGC 6946). This difference may be due to the relative deficit of recent CRe^- injection into the interstellar medium (ISM) for the galaxies having largely quiescent disks.Comment: 41 pages including 6 tables and 12 figures; accepted for publication in the Astrophysical Journal. A full-resolution color version can be found at http://www.astro.yale.edu/murphy/a-ph/murphy_FIR-radio.pdf ; Corrected typo

Host Plant Induced Variation in Gut Bacteria of Helicoverpa armigera

Helicoverpa are important polyphagous agricultural insect pests and they have a worldwide distribution. In this study, we report the bacterial community structure in the midgut of fifth instar larvae of Helicoverpa armigera, a species prevalent in the India, China, South Asia, South East Asia, Southern & Eastern Africa and Australia. Using culturable techniques, we isolated and identified members of Bacillus firmus, Bacillus niabense, Paenibacillus jamilae, Cellulomonas variformis, Acinetobacter schindleri, Micrococcus yunnanesis, Enterobacter sp., and Enterococcus cassiliflavus in insect samples collected from host plants grown in different parts of India. Besides these the presence of Sphingomonas, Ralstonia, Delftia, Paracoccus and Bacteriodetes was determined by culture independent molecular analysis. We found that Enterobacter and Enterococcus were universally present in all our Helicoverpa samples collected from different crops and in different parts of India. The bacterial diversity varied greatly among insects that were from different host plants than those from the same host plant of different locations. This result suggested that the type of host plant greatly influences the midgut bacterial diversity of H. armigera, more than the location of the host plant. On further analyzing the leaf from which the larva was collected, it was found that the H. armigera midgut bacterial community was similar to that of the leaf phyllosphere. This finding indicates that the bacterial flora of the larval midgut is influenced by the leaf surface bacterial community of the crop on which it feeds. Additionally, we found that laboratory made media or the artificial diet is a poor bacterial source for these insects compared to a natural diet of crop plant

Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis

We present new full-sky temperature maps in five frequency bands from 23 to 94 GHz, based on the first three years of the WMAP sky survey. The new maps, which are consistent with the first-year maps and more sensitive, incorporate improvements in data processing made possible by the additional years of data and by a more complete analysis of the polarization signal. These include refinements in the gain calibration and beam response models. We employ two forms of multi-frequency analysis to separate astrophysical foreground signals from the CMB, each of which improves on our first-year analyses. First, we form an improved 'Internal Linear Combination' map, based solely on WMAP data, by adding a bias correction step and by quantifying residual uncertainties in the resulting map. Second, we fit and subtract new spatial templates that trace Galactic emission; in particular, we now use low-frequency WMAP data to trace synchrotron emission. The WMAP point source catalog is updated to include 115 new sources. We derive the angular power spectrum of the temperature anisotropy using a hybrid approach that combines a maximum likelihood estimate at low l (large angular scales) with a quadratic cross-power estimate for l>30. Our best estimate of the CMB power spectrum is derived by averaging cross-power spectra from 153 statistically independent channel pairs. The combined spectrum is cosmic variance limited to l=400, and the signal-to-noise ratio per l-mode exceeds unity up to l=850. The first two acoustic peaks are seen at l=220.8 +- 0.7 and l=530.9 +- 3.8, respectively, while the first two troughs are seen at l=412.4 +- 1.9 and l=675.1 +- 11.1, respectively. The rise to the third peak is unambiguous; when the WMAP data are combined with higher resolution CMB measurements, the existence of a third acoustic peak is well established.Comment: 116 pgs, 24 figs. Accepted version of the 3-year paper as posted to http://lambda.gsfc.nasa.gov/product/map/dr2/map_bibliography.cfm in January 200