Changes in amino acid enantiomers and microbial performance in soils from a subtropical mountain oasis in Oman abandoned for different periods

An important feature of maintaining the agricultural stability in millennia-old mountain oases of northern Oman is the temporary abandonment of terraces. To analyse the effects of a fallow period on soil microbial performance, i.e. microbial activity and microbial biomass, samples of eight terrace soils abandoned for different periods were collected in situ, assigned to four fallow age classes and incubated for 30 days in the laboratory after rewetting. The younger fallow age classes of 1 and 5 years were based on the records of the farmers recollections, the two older fallow age classes of 10–20 and 25–60 years according to the increase in the d -to- l ratio of valine and leucine enantiomers. The increase in these two ratios was in agreement with that of the d -to- l ratio of lysine. The strongest relationship was observed between the increase in the d -to- l ratio of lysine and the decrease in soil microbial biomass C. However, the most stringent coherence between the increase in fallow age and soil properties was revealed by the decreases in cumulative respiration and net N mineralisation rates with decreasing availability of substrate to soil microorganisms. During the 30-day incubation following rewetting, relative changes in microbial activity (respiration and net N mineralisation) and microbial biomass (C and N) indices were similar in the eight terrace soils on a fallow age-class-specific level, indicating that the same basic processes occurred in all of the sandy terrace soils investigated.     

The real-time stellar evolution of Sakurai's object

After a hot white dwarf ceases its nuclear burning, its helium may briefly and explosively reignite. This causes the star to evolve back into a cool giant, whereupon it experiences renewed mass ejection before reheating. A reignition event of this kind was observed in 1996 in V4334 Sgr (Sakurai's object). Its temperature decrease was 100 times the predicted rate. To understand its unexpectedly fast evolution, we have developed a model in which convective mixing is strongly suppressed under the influence of flash burning. The model predicts equally rapid reheating of the star. Radio emission from freshly ionized matter now shows that this reheating has begun. Such events may be an important source of carbon and carbonaceous dust in the Galaxy.     

WaLIS—A simple model to simulate water partitioning in a crop association: The example of an intercropped vineyard

The introduction of cover crops in vineyards is being tested as it mitigates some undesirable environmental impacts of these cropping systems, such as surface runoff and soil erosion. In some cases, it could even reduce an excessive vegetative vigour of grapevine. However, most of time, wine growers are worried that severe competition for soil resources between the intercrop and grapevines could impair grape yield and quality. WaLIS (Water baLance for Intercropped Systems), a simple model simulating the water resource partitioning in such an association was designed to evaluate and optimize the water regime in intercropped systems.The model is presented and evaluated in this paper in three situations: the same grapevine cultivar (cv. Aranel) with either bare soil, or a temporary intercrop (barley) or a permanent intercrop (tall fescue). All three situations are located in the south of France. It is based on an existing model, designed to simulate the water regime of a bare soil vineyard, which was adapted to take into account the specific features of intercropped systems. Hence it includes a two-compartment representation of the soil particularly adapted to row crops. The simulation of a grass cover growth and its transpiration were added. Finally, particular importance was dedicated to the simulation of surface runoff which was the main source of the original model deviation during the winter period and made difficult multi-year simulations. Now, the model appears to be able to evaluate perennial cropping systems and provide decision support.The WaLIS model simulated the water available for both grapevine and intercrop well, and it proved to be efficient in most of the tested situations and years. The modelling of the water stress experienced by both crops was also generally good and all water fluxes simulated by the model were realistic. The main observed deviation in the simulation of the water soil content occurred during winter, i.e. outside the grapevine growth period. It was very likely due to the use of a constant parameter value for the surface runoff which did not take into account of changes in the soil surface and their effects on water infiltration.Finally, the analysis of sensitivity made on the WaLIS model showed that it is robust and sensitive to a few parameters, which drive the maximal grapevine transpiration and soil evaporation or are linked to the surface runoff simulation. The work also revealed how a good estimate of the total soil water available for each crop is crucial. This model, easy to use and parameterise, can provide sound management advice for designing valuable intercropped cropping systems.     

Angiotensin II type 2 receptor signaling attenuates aortic aneurysm in mice through ERK antagonism

Angiotensin II (AngII) mediates progression of aortic aneurysm, but the relative contribution of its type 1 (AT1) and type 2 (AT2) receptors remains unknown. We show that loss of AT2 expression accelerates the aberrant growth and rupture of the aorta in a mouse model of Marfan syndrome (MFS). The selective AT1 receptor blocker (ARB) losartan abrogated aneurysm progression in the mice; full protection required intact AT2 signaling. The angiotensin-converting enzyme inhibitor (ACEi) enalapril, which limits signaling through both receptors, was less effective. Both drugs attenuated canonical transforming growth factor-β (TGFβ) signaling in the aorta, but losartan uniquely inhibited TGFβ-mediated activation of extracellular signal-regulated kinase (ERK), by allowing continued signaling through AT2. These data highlight the protective nature of AT2 signaling and potentially inform the choice of therapies in MFS and related disorders.     

Evaluation of biological variance of cystatin C in comparison with other endogenous markers of glomerular filtration rate in healthy dogs

BACKGROUND: The aim of the study was to investigate and compare components of variance of endogenous markers of glomerular filtration rate (GFR) in healthy dogs and impact on the interpretation of results. HYPOTHESIS: Cystatin C (cysC) in the dog is superior to creatinine (crea) and urea in detecting decreased renal function because of a high index of individuality (IoI). ANIMALS AND METHOD: Variance components of cysC, crea (2 methods: creaE, creaJ), urea, and inorganic phosphate (Pi) in plasma were determined in a longitudinal study over 6 months in 24 healthy dogs (6 German Shorthair Pointers, 18 Beagles). IoI and critical differences (CD) were calculated, as well as the numbers of measurements necessary to determine the individual's homeostatic set point. Results: Mean concentrations of cysC, creaJ, creaE, urea, and Pi (mean +/- SD) were 0.93 +/- 0.19 mg/L, 0.94 +/- 0.17 mg/dL, 0.76 +/- 0.18 mg/dL, 35.34 +/- 9.08 mg/dL, and 3.74 +/- 0.68 mg/dL, respectively. The IoI for cysC, creaJ, creaE, urea, and Pi were 0.96, 0.89, 0.80, 0.90, and 1.16, respectively. The C(D) for cysC, creaJ, creaE, urea, and Pi were 0.37 mg/L, 0.26 mg/dL, 0.27 mg/dL, 16.94 mg/dL, and 1.45 mg/dL, respectively. CONCLUSION: In dogs, components of biological variance of cysC and crea are in the same range. Analytical precision requirements were fulfilled by crea(both), urea, and Pi. All parameters had an intermediate IoI, which allowed the application of population-based reference limits. The application of the CD for crea or cysC might be useful in detecting a decrease of GFR, when sequential measurements in an individual reveal an increase exceeding the CD but not the upper reference limit.     

Comment on "Phonemic diversity supports a serial founder effect model of language expansion from Africa"

Atkinson (Reports, 15 April 2011, p. 346) argues that the phonological complexity of languages reflects the loss of phonemic distinctions due to successive founder events during human migration (the serial founder hypothesis). Statistical simulations show that the type I error rate of Atkinson's analysis is hugely inflated. The data at best support only a weak interpretation of the serial founder hypothesis.