Simulating mycorrhiza contribution to forest C- and N cycling-the MYCOFON model

Although mycorrhiza has been identified to be of major importance for plant nutrition and ecosystem stability, existing C- and N- simulation models on the ecosystem scale do not explicitly consider the feedbacks between ectomycorrhizal fungi and plants. We present a simple dynamic feedback model which allows estimating the main C- and N- flows between ectomycorrhizal fungi and tree roots in order to test the sensitivity of the system fungus-tree to environmental parameters and to assess the fungal contribution to plant N nutrition. Sensitivity tests carried out showed that the model responses to variations of model parameters, particularly with regard to N availability, are in agreement with published results from field and laboratory studies. However, there are still some processes and parameters which are not well constrained. Fungal N uptake rates and the ratio between mycelium, hartig net, and mantle biomass are parameters which significantly affect model results but for which published data are scarce or missing. Nevertheless, the model is already providing a platform to test our understanding of the importance of mycorrhiza for forest stand nutrition. Future coupling to a mechanistic ecosystem model will allow simulating the importance of mycorrhization for e.g. stand growth and C and N retention

Body image, cosmesis, quality of life, and functional outcome of hand-assisted laparoscopic versus open restorative proctocolectomy: long-term results of a randomized trial

BACKGROUND: This study aimed to compare quality of life (QOL), functional outcome, body image, and cosmesis after hand-assisted laparoscopic (LRP) versus open restorative proctocolectomy (ORP). The potential long-term advantages of LRP over ORP remain to be determined. The most likely advantage of LRP is the superior cosmetic result. It is, however, unclear whether the size and location of incisions affect body image and QOL. METHODS: In a previously conducted randomized trial comparing LRP with ORP, 60 patients were prospectively evaluated. The primary end points were body image and cosmesis. The secondary end points were morbidity, QOL, and functional outcome. A body image questionnaire was used to evaluate body image and cosmesis. The Short Form-36 Health Survey and the Gastrointestinal Quality of Life Inventory were used to assess QOL. Body image and QOL also were assessed preoperatively. RESULTS: A total of 53 patients completed the QOL and functional outcome questionnaires. There were no differences in functional outcome, morbidity, or QOL between LRP and ORP. At a median of 2.7 years after surgery, 46 patients returned the questionnaires regarding body image, cosmesis, and morbidity. The body image and cosmesis scores of female patients were significantly higher in the LRP group than in the ORP group (body image, 17.4 vs 14.9; cosmesis, 19.1 vs 13.0, respectively). The female patients in the ORP group had significantly lower body image scores than the male patients (14.9 vs 18.3). CONCLUSIONS: This study is the first to show that ORP has a negative impact on body image and cosmesis as compared with LRP. Functional outcome, QOL, and morbidity are similar for the two approaches. The advantages of a long-lasting improved body image and cosmesis for this relatively young patient population may compensate for the longer operating times and higher costs, particularly for wome

Inhibition of Apoplastic and Symplastic Peroxidase Activity from Norway Spruce by the Photooxidant Hydroxymethyl Hydroperoxide

Young, clonal Norway spruce trees (Picea abies L.) were exposed for 2 years at high altitudes to ambient atmospheric concentrations of photooxidants containing hydroxymethyl hydroperoxide (HMHP) as an important constituent. In spruce needles from a site with higher concentrations of organic peroxides in air, the apoplastic peroxidase activities were significantly lower than in needles exposed to lower organic peroxide concentrations. Guaiacol peroxidase activities in total needle extracts were not affected. In vitro HMHP at a concentration of 35 [mu]M inhibited apoplastic and total needle guaiacol peroxidase activities by 50% at pH 5.25. At the same pH, ascorbate-specific peroxidase activity required about 100 [mu]M HMHP for 50% inhibition. At pH 7, 1.46 mM HMHP caused a 50% reduction in guaiacol peroxidase and a 13% reduction in ascorbate peroxidase activity. The present results suggest that HMHP in ambient air may affect peroxidase activity in spruce needles. Peroxidases located in the relatively acidic aqueous phase of the cell walls appear to be more susceptible to HMHP inhibition than those present in neutral or slightly alkaline symplastic compartments of cells such as the cytosol or chloroplasts

Selected reactive oxygen species and antioxidant enzymes in common bean after Pseudomonas syringae pv. phaseolicola and Botrytis cinerea infection

Phaseolus vulgaris cv. Korona plants were inoculated with the bacteria Pseudomonas syringae pv. phaseolicola (Psp), necrotrophic fungus Botrytis cinerea (Bc) or with both pathogens sequentially. The aim of the experiment was to determine how plants cope with multiple infection with pathogens having different attack strategy. Possible suppression of the non-specific infection with the necrotrophic fungus Bc by earlier Psp inoculation was examined. Concentration of reactive oxygen species (ROS), such as superoxide anion (O2 -) and H2O2 and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined 6, 12, 24 and 48 h after inoculation. The measurements were done for ROS cytosolic fraction and enzymatic cytosolic or apoplastic fraction. Infection with Psp caused significant increase in ROS levels since the beginning of experiment. Activity of the apoplastic enzymes also increased remarkably at the beginning of experiment in contrast to the cytosolic ones. Cytosolic SOD and guaiacol peroxidase (GPOD) activities achieved the maximum values 48 h after treatment. Additional forms of the examined enzymes after specific Psp infection were identified; however, they were not present after single Bc inoculation. Subsequent Bc infection resulted only in changes of H2O2 and SOD that occurred to be especially important during plant–pathogen interaction. Cultivar Korona of common bean is considered to be resistant to Psp and mobilises its system upon infection with these bacteria. We put forward a hypothesis that the extent of defence reaction was so great that subsequent infection did not trigger significant additional response

Tissue tolerance: an essential but elusive trait for salt-tolerant crops

For a plant to persist in saline soil, osmotic adjustment of all plant cells is essential. The more salt-tolerant species accumulate Na+ and Cl– to concentrations in leaves and roots that are similar to the external solution, thus allowing energy-efficient osmotic adjustment. Adverse effects of Na+ and Cl– on metabolism must be avoided, resulting in a situation known as ‘tissue tolerance’. The strategy of sequestering Na+ and Cl– in vacuoles and keeping concentrations low in the cytoplasm is an important contributor to tissue tolerance. Although there are clear differences between species in the ability to accommodate these ions in their leaves, it remains unknown whether there is genetic variation in this ability within a species. This viewpoint considers the concept of tissue tolerance, and how to measure it. Four conclusions are drawn: (1) osmotic adjustment is inseparable from the trait of tissue tolerance; (2) energy-efficient osmotic adjustment should involve ions and only minimal organic solutes; (3) screening methods should focus on measuring tolerance, not injury; and (4) high-throughput protocols that avoid the need for control plants and multiple Na+ or Cl- measurements should be developed. We present guidelines to identify useful genetic variation in tissue tolerance that can be harnessed for plant breeding of salt tolerance

Draft Nuclear Genome, Complete Chloroplast Genome, and Complete Mitochondrial Genome for the Biofuel/ Bioproduct Feedstock Species Scenedesmus obliquus Strain DOE0152z

The green alga Scenedesmus obliquus is an emerging platform species for the industrial production of biofuels. Here, we report the draft assembly and annotation for the nuclear, plastid, and mitochondrial genomes of S. obliquus strain DOE0152z

Vocal fold medialization: which are the available fillers in France in 2010?

peer reviewe

Molecular mechanism of protrusion formation during cell-to-cell spread of Listeria

The bacterial pathogen Listeria monocytogenes spreads within human tissues using a motility process dependent on the host actin cytoskeleton. Cell-to-cell spread involves the ability of motile bacteria to remodel the host plasma membrane into protrusions, which are internalized by neighboring cells. Recent results indicate that formation of Listeria protrusions in polarized human cells involves bacterial antagonism of a host signaling pathway comprised of the scaffolding protein Tuba and its effectors N-WASP and Cdc42. These three human proteins form a complex that generates tension at apical cell junctions. Listeria relieves this tension and facilitates protrusion formation by secreting a protein called InlC. InlC interacts with a Src Homology 3 (SH3) domain in Tuba, thereby displacing N-WASP from this domain. Interaction of InlC with Tuba is needed for efficient Listeria spread in cultured human cells and infected animals. Recent structural data has elucidated the mechanistic details of InlC/Tuba interaction, revealing that InlC and N-WASP compete for partly overlapping binding surfaces in the Tuba SH3 domain. InlC binds this domain with higher affinity than N-WASP, explaining how InlC is able to disrupt Tuba/N-WASP complexes.Grants from the National Institutes of Health (R01AI085072) and the Marsden Fund of the Royal Society of New Zealand (UOO1003), Medical Research Council of South Africa, the National Research Foundation of South Africa and previously by the Helmholtz Centre for Infection Research, Braunschweig, Germany.http://www.frontiersin.org/Cellular_and_Infection_Microbiologyhb201