Mechanism of arsenate resistance in the ericoid mycorrhizal fungus Hymenoscyphus ericae

Arsenate resistance is exhibited by the ericoid mycorrhizal fungus Hymenoscyphus ericae collected from As-contaminated mine soils. To investigate the mechanism of arsenate resistance, uptake kinetics for arsenate (H(2)AsO(4)(-)), arsenite (H(3)AsO(3)), and phosphate (H(2)PO(4)(-)) were determined in both arsenate-resistant and -non-resistant H. ericae. The uptake kinetics of H(2)AsO(4)(-), H(3)AsO(3), and H(2)PO(4)(-) in both resistant and non-resistant isolates were similar. The presence of 5.0 microM H(2)PO(4)(-) repressed uptake of H(2)AsO(4)(-) and exposure to 0.75 mM H(2)AsO(4)(-) repressed H(2)PO(4)(-) uptake in both H. ericae. Mine site H. ericae demonstrated an enhanced As efflux mechanism in comparison with non-resistant H. ericae and lost approximately 90% of preloaded cellular As (1-h uptake of 0.22 micromol g(-1) dry weight h(-1) H(2)AsO(4)(-)) over a 5-h period in comparison with non-resistant H. ericae, which lost 40% of their total absorbed H(2)AsO(4)(-). As lost from the fungal tissue was in the form of H(3)AsO(3). The results of the present study demonstrate an enhanced H(3)AsO(3) efflux system operating in mine site H. ericae as a mechanism for H(2)AsO(4)(-) resistance. The ecological significance of this mechanism of arsenate resistance is discussed.

Dry gel conversion of organosilane templated mesoporous silica: from amorphous to crystalline catalysts for benzene oxidation

Mesoporous silica grown using [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride as the mesoporogen in the presence of Fe and Al is X-ray amorphous, but contains very small domains with features of MFI zeolite as evidenced by IR and Raman spectroscopy. When applied as a catalyst, this amorphous sample shows good performance in the selective oxidation of benzene using nitrous oxide. Addition of tetrapropylammonium as structure directing agent to the as-synthesized mesoporous silica and subsequent dry gel conversion results in the formation of hierarchical Fe/ZSM-5 zeolite. During dry gel conversion the wormhole mesostructure of the initial material is completely lost. A dominant feature of the texture after crystallization is the high interconnectivity of micropores and mesopores. Substantial redistribution of low-dispersed Fe takes place during dry gel conversion towards highly dispersed isolated Fe species outside the zeolite framework. The catalytic performance in the oxidation of benzene to phenol of these highly mesoporous zeolites is appreciably higher than that of the parent material.

The use and meanings of 'time of wetness' in understanding stone decay

Moisture is a well documented, and crucial, control on the nature of stone decay. The term time of wetness has frequently been adopted to describe how long a stone block is wet, with a view to understanding the impact of this on decay processes. Although this term has proved conceptually useful, it has been used in different ways, by different groups to mean mean quite different things. For example, the time of wetness for a stone block surface (the traditional understanding) may be quite different from that of a block interior, controlled by the different dynamics of wetting and drying in those zones. Thus, surface wetting will occur regularly (sometimes swiftly followed by drying, depending on the time of year), with block interior wetting requiring the accumulation of surface moisture to penetrate to depth (more likely in autumn and winter months), and drying out much more slowly. This relatively new but important perspective, framed in the context of climate change, is crucial to understanding the length of time stone may remain damp at depth following a period of prolonged precipitation. The nature and speed of drying is also relevant in quantifying time of wetness of both surfaces and the interior of building stones.
These ideas related to time of wetness have implications for decay processes, specifically how a prolonged time of deep wetness may re-focus the emphasis of salt weathering in natural building stones toward chemical action. Literature on chemical change is discussed, suggesting that chemical change occurring during periods of prolonged wetness is likely to be significant in itself, with implications for weakening the stone (in terms of, for example, cement dissolution or grain boundary weakening) and exacerbating physical damage from salt crystallisation when blocks finally dry out.

The difficult coughing child:prolonged acute cough in children

Cough is one of the most common symptoms that patients bring to the attention of primary care clinicians. Cough can be designated as acute ( 8 weeks in duration). The use of the term 'prolonged acute cough' in a cough guideline allows a period of natural resolution to occur before further investigations are warranted. The common causes are in children with post viral or pertussis like illnesses causing the cough. Persistent bacterial bronchitis typically occurs when an initial dry acute cough due to a viral infection becomes a prolonged wet cough remaining long after the febrile illness has resolved. This cough responds to a completed course of appropriate antibiotics.

The effects of climate change on ovine parasitic gastroenteritis determined using veterinary surveillance and meteorological data for Northern Ireland over the period 1999-2009

While the influence of temperature and moisture on the free-living stages of gastrointestinal nematodes have been described in detail, and evidence for global climate change is mounting, there have been only a few attempts to relate altered incidence or seasonal patterns of disease to climate change. Studies of this type have been completed for England Scotland and Wales, but not for Northern Ireland (NI). Here we present an analysis of veterinary diagnostic data that relates three categories of gastrointestinal nematode infection in sheep to historical meteorological data for NI. The infections are: trichostrongylosis/teladorsagiosis (Teladorsagia/Trichostrongylus), strongyloidosis and nematodirosis. This study aims to provide a baseline for future climate change analyses and to provide basic information for the development of nematode control programmes. After identifying and evaluating possible sources of bias, climate change was found to be the most likely explanation for the observed patterns of change in parasite epidemiology, although other hypotheses could not be refuted. Seasonal rates of diagnosis showed a uniform year-round distribution for Teladorsagia and Trichostrongylus infections, suggesting consistent levels of larval survival throughout the year and extension of the traditionally expected seasonal transmission windows. Nematodirosis showed a higher level of autumn than Spring infection, suggesting that suitable conditions for egg and larval development occurred after the Spring infection period. Differences between regions within the Province were shown for strongyloidosis, with peaks of infection falling in the period September-November. For all three-infection categories (trichostrongylosis/teladorsagiosis, strongyloidosis and nematodirosis), significant differences in the rates of diagnosis, and in the seasonality of disease, were identified between regions. (C) 2012 Elsevier B.V. All rights reserved.

Maltese Temple Period figurines.

Malone, C and S. Stoddart (Ed). T.Insoll Chapter on Maltese figurines.

Coleoptera and microbe biomass in Antarctic Dry Valley paleosols adjacent to the Inland Ice: Implications for Mars

Bulk paleosol samples collected from a Middle to Early Miocene moraine in the New Mountain area of the Dry Valleys, Antarctica, yielded Coleoptera exoskeletons and occasional endoskeletons showing considerable diagenetic effects along with several species of bacteria, all lodged in a dry-frozen but salt-rich horizon at shallow depth to the land surface. The till is at the older end of a chronologic sequence of glacial deposits, thought to have been deposited before the transition from wet-based to cold-based ice (similar to 15 Ma), and hence, entirely weathered in contact with the subaerial atmosphere. It is possible, though not absolutely verifiable, that the skeletons date from this early stage of emplacement having undergone modifications whenever light snowmelt occurred or salt concentrations lowered the freezing temperature to maintain water as liquid. Correlation of the Coleoptera species with cultured bacteria in the sample and the likelihood of co-habitation with Beauveria bassiani found in two adjacent, although younger paleosols, leads to new questions about the antiquity of the Coleoptera and the source of N and glucose from chitinase derived from the insects. The skeletons in the 831 section may date close to the oldest preserved chitin (Oligocene) yet found on Earth. While harsh Martian conditions make it seemingly intolerable for complex, multicellular organisms such as insects to exist in the near-surface and subaerially, life within similar cold, dry paleosol microenvironments (Cryosols) of Antarctica point to life potential for the Red Planet, especially when considering the relatively diverse microbe (bacteria and fungi) population. (C) 2011 Elsevier Ltd. All rights reserved.

A Chronological Framework for the Period 208 BC to AD 600

The period, from the Iron Age through to what is sometimes
called the Early Christian Period or the Early Middle Ages, includes
some of the most enigmatic centuries in the whole of Irish
history. In this article we intend to look at various strands of evidence
that have become available from the perspective of dendrochronology.
However, interpretation of dendrochronological
results works best when there is other information to push
against. In the case of this period one of the best sources of parallel
information – information essentially as well dated as tree
rings – has to be records of atmospheric chemistry from the ice
cores that have been drilled at several locations across Greenland.
Combining such information with evidence from tree rings,
palaeoecological research, and occasionally from history, allows
us to trace out a series of events and episodes that form the beginnings
of an understanding of this period between the Iron
Age flowering – with sites such as Emain Mache, Tara, Cruachain
– and the Early Christian flowering – widespread foundation of churches and monasteries.

Geochemical records of palaeoenvironmental controls on peat forming processes in the Mfabeni peatland, Kwazulu Natal, South Africa since the Late Pleistocene

The Mfabeni peatland is the only known sub-tropical coastal fen that transcends the Last Glacial Maximum (LGM). This ca. 10m thick peat sequence provides a continuous sedimentation record spanning from the late Pleistocene to present (basal age c. 47kcalyr BP). We investigated the paleaeoenvironmental controls on peat formation and organic matter source input at the Mfabeni fen by: 1) exploring geochemical records (mass accumulation rate, total organic carbon, carbon accumulation rate, δC, δN and C/N ratio) to delineate primary production, organic matter source input, preservation and diagenetic processes, and 2) employ these geochemical signatures to reconstruct the palaeoenvironmental conditions and prevailing climate that drove carbon accumulation in the peatland. We established that the Mfabeni peat sediments have undergone minimal diagenetic alteration. The peat sequence was divided into 5 linear sedimentation rate (LSR) stages indicating distinct changes in climate and hydrological conditions: LSR stage 1 (c. 47 to c. 32.2kcalyr BP): predominantly cool and wet climate with C4 plant assemblages, interrupted by two short warming events. LSR stage 2 (c. 32.2 to c. 27.6kcalyr BP): dry and windy climate followed by a brief warm and wet period with increased C4 sedge swamp vegetation. LSR stage 3 (c. 27.6 to c. 20.3kcalyr BP): initial cool and wet period with prevailing C4 sedge plant assemblage until c. 23kcalyr BP; then an abrupt change to dry and cool glacial conditions and steady increases in C3 grasses. LSR stage 4 (c. 20.3 to c. 10.4kcalyr BP): continuation of cool and dry conditions and strong C3 grassland signature until c. 15kcalyr BP, after which precipitation increases. LSR stage 5 (c. 10.4kcalyr BP to present): characterised by extreme fluctuations between pervasive wet and warm to cool interglacial conditions with intermittent abrupt millennial-scale cooling/drying events and oscillations between C3 and C4 plant assemblages. In this study we reconstructed a high-resolution record of local hydrology, bulk plant assemblage and inferred climate since the Late Pleistocene, which suggest an anti-phase link between Southern African and the Northern Hemisphere, most notably during Heinrich (5 to 2) and Younger Dryas events. © 2013 Elsevier B.V.

Potassium-doped Ni-MgO-ZrO catalysts for dry reforming of methane to synthesis gas

Ni/K-MgO-ZrO catalysts for dry reforming of methane, with a range of Mg/Zr ratios and each containing about 10 wt% Ni, were prepared via Ni nitrate impregnation on MgO-ZrO supports synthesized by co-precipitation using KCO. It was found that a proportion of the potassium of the precipitant remained in the samples and improved the stability of the catalysts in the reaction. It was also shown that reduction of the catalysts at 1,023 K without calcination in air is necessary for stable and high activity; calcination in air at 1,073 K gives a deterioration of the catalytic properties, leading to rapid deactivation during the reaction. The order of the CH conversions of the reduced catalysts after 14 h on stream was as follows: Ni/K-MgZr ~ Ni/K-Mg ≥ Ni/K-MgZr Ni/K-Zr. A catalyst with 0.95 wt% K on MgO-ZrO with a Mg:Zr mole ratio of 5:2 showed the best resistance to deactivation. Experiments in a microbalance system showed that there was only negligible coke deposition on the surface of this sample. This behaviour was attributed to the presence of Ni nanoparticles with a diameter of less than 10 nm located on a MgO/NiO solid solution shell doped by K ions; this in turn covers a core of tetragonal ZrO and/or a MgO/ZrO solid solution. This conclusion was supported by EDS/TEM, XPS, XRD and H chemisorption measurements. © 2013 Springer Science+Business Media New York.

Holocene floodplain palaeoecology of the Humberhead Levels; implications for regional wetland development

The acquisition of high quality, well-dated local site records is essential for progressing regional environmental reconstructions. As part of a wider study designed to examine intra- and extra- site ecosystem responses to environmental change, this paper presents new palaeoecological data from the floodplain of the River Torne in the Humberhead Levels, South Yorkshire. The sampling site lies adjacent to the lowland raised mire of Hatfield Moors, a location with a long history of palaeoecological investigations. The potential of using floodplain records to reconstruct local variations in ecosystem response to environmental change is also considered. Coleoptera and pollen are used to reconstruct floodplain ecosystem dynamics, whilst chronologies are established using Bayesian age–depth modelling. Between 10,200 cal BP and 2300 cal BP, the floodplain experienced multiple phases of ecological change. At 10,200–9910 cal BP, a cut-off channel began to infill with peat, while the surrounding floodplain remained relatively dry with Pinus forest growing nearby. Between 9630–9500 cal BP and 7270–7020 cal BP, a depositional hiatus occurred in the sedimentary record. By the end of this period, the local woodland had diversified and expanded to mixed deciduous tree cover. A wet shift identified at 6870–6160 cal BP was shortly followed by a rise in Alnus and Tilia from 6410–6160 cal BP. At this time, widespread floodplain paludification had occurred in the Humberhead Levels, which was largely controlled by relative sea-level (RSL) rise and the associated rise in regional water tables. Floodplain expansion also resulted in the widespread occurrence of Alnus dominated fen woodland. The local Torne floodplain experienced varying levels of wetness that influenced the decline and subsequent regeneration of the woodland from 5870–5640 cal BP. At this time, the Ulmus decline is identified in the pollen stratigraphic record. Floodplain hydrology appears to have been controlled by a combination of water table fluctuations and changes in channel pattern/flow, both of which can be linked to RSL variations recorded in the Humber Estuary. Floodplain alluviation, also linked to rising water tables, is dated to 4360–4160 cal BP. Anthropogenic woodland clearance further upstream may have further compounded this event.