Properties of an extracellular amylase purified from a Bacillus species

A strain of Bacillus produced an amylase with properties characteristically different from known bacterial amylases. The purified 80 kDa protein of pI 5.1 dextrinized starch, glycogen and pullulan. The temperature and pH optima of the enzyme were 60 °C and 6.6 respectively. In the presence of 0.05 M CaCl₂, the enzyme retained stability for 15 min at 80 °C. Antibodies raised to the amylase protein showed no reaction with -amylases of Bacillus sp. and B. licheniformis. In culture, proteolytic degradation of the enzyme was observed.     

Non-identifiability of the Rayleigh damping material model in Magnetic Resonance Elastography

Magnetic Resonance Elastography (MRE) is an emerging imaging modality for quantifying soft tissue elasticity deduced from displacement measurements within the tissue obtained by phase sensitive Magnetic Resonance Imaging (MRI) techniques. MRE has potential to detect a range of pathologies, diseases and cancer formations, especially tumors. The mechanical model commonly used in MRE is linear viscoelasticity (VE). An alternative Rayleigh damping (RD) model for soft tissue attenuation is used with a subspace-based nonlinear inversion (SNLI) algorithm to reconstruct viscoelastic properties, energy attenuation mechanisms and concomitant damping behavior of the tissue-simulating phantoms. This research performs a thorough evaluation of the RD model in MRE focusing on unique identification of RD parameters, _μI${\mu }_I$ and _ρI${\rho }_I$.     

CARAGANA FABR. PROMOTES REVEGETATION AND SOIL REHABILITATION IN SALINE-ALKALI WASTELAND

To determine how plantations of Caragana microphylla shrubs affect saline-alkali soil amelioration and revegetation, we investigated the vegetation and sampled soils from saline-alkali wasteland (SAW), perennial Caragana forestland (PCF), Caragana forest after fire disturbance (CFF). Results showed that with the development of Caragana Fabr., highly dominant species of Poaceae family, including Elymus dahuricus, Thermopsis lanceolata, Stipa tianschanica, died out in PCF. Moreover, Papilionaceae family, including Lespedeza indica, Oxytropis psammocharis, and Astragalus scaberrimus, was established both in PCF and CFF. Phytoremediation of saline-alkali wasteland (SAW) was achieved by plantation, resulting in the reduced soil pH, sodium adsorption ratio, exchangeable sodium percentage, salinity, and Na⁺ concentration around Caragana shrubs. Greater amounts of soil organic, total nitrogen, ammonium nitrogen, available phosphorus, and available potassium were observed in PCF topsoil than in SAW topsoil. The concentration of mineralized N in PCF soil was significantly lower than that in SAW soil at all sampled depths, indicating that Caragana shrubs were just using N and therefore less measured in soils. Fire disturbance resulted in decreased soil pH and salinity, but increased organic content, total nitrogen, and ammonium nitrogen. The improved soil parameters and self-recovery of shrubs indicated that Caragana shrubs were well established after burning event.     

Brushing effects on the growth and mechanical properties of Corispermum mongolicum vary with water regime

High water availability and mechanical stress can induce opposite responses in plants. In arid areas of Northern China the occurrence of high wind and high water availability tend to be negatively correlated. Since turgor pressure is a determinant of the mechanical stability of annuals, it is hypothesised that the effects of mechanical perturbation (MP) on annuals may depend on soil water availability. To test this proposal, we conducted an experiment in which a pioneering annual Corispermum mongolicum was subjected to two levels of MP and water supply, and then determined its growth and mechanical traits. Brushing had no effect on plant height and total biomass, but stimulated leaf and branch production. Water supply affected plant height, basal diameter, total biomass and stem rigidity, but not leaf and branch number, root/shoot ratio or flexibility. With high water availability, brushing stimulated the production of stiffer stems (thicker and with a higher Young's modulus) and more roots relative to shoot mass, but with low water availability MP induced the opposite response. This shows that both the degree and direction of plant responses to MP depend on the presence of other factors. We discuss how the interactive effects of MP and water availability on growth and mechanical properties may help C. mongolicum to establish in windy and arid environments.