Proper supply of S increases GSH synthesis in the establishment and reduces tiller mortality during the regrowth of Tanzania guinea grass used for Cd phytoextraction

Purpose

Cadmium has caused serious environmental problems due to its phytotoxicity, requiring solutions to reduce its concentration in the environment. Because S can alleviate the phytotoxicity caused by heavy metals, the evaluation of the effects of S supply is a promising approach to address this problem. The aim of this study was to determine the influence of S in reducing the phytotoxicity caused by Cd to Panicum maximum Jacq. cv. Tanzania (guinea grass) and to evaluate the potential of this grass for Cd phytoextraction.

Materials and methods

Tanzania guinea grass was cultivated in a nutrient solution to evaluate the combinations of five rates of S (0.1, 1.0, 1.9, 2.8, and 3.7 mmol L^?1) and five rates of Cd (0.0, 0.5, 1.0, 1.5, and 2.0 mmol L^?1), in a 5² fractional factorial design with six replications. Six plants were grown per pot in two growth periods to evaluate the effect of Cd on the establishment (51 days of age) and on the regrowth (18 days of growth) of the plants. During regrowth, Cd was not supplied in the nutrient solution. At the end of each growth period, growth parameters, concentrations of S and Cd, Cd transport factor, and concentrations of hydrogen peroxide (H₂O₂), malondialdehyde, reduced glutathione, and oxidized glutathione were evaluated.

Results and discussion

On the establishment of Tanzania guinea grass, application of Cd reduced mass production by 39 % due to the increases in the concentration of Cd (30 times compared with the treatment without Cd) and in lipid peroxidation (124 %). During regrowth, the residual effect of Cd resulted in a lower number of tillers (62 %) and leaves (89 %) caused by the increase in concentrations of Cd, H₂O₂ (49 %), and lipid peroxidation, which resulted in a 65 % lower dry mass production. The proper supply of S reduced concentration of Cd and tiller mortality rate due to the residual effect of Cd on the regrowth of the grass. Mass production by the roots was 43 % lower because of Cd, but the transport of Cd from roots to shoots increased. The increase in the concentration of glutathione (GSH) associated with a possible higher activity of antioxidant enzymes alleviated the phytotoxic effects of Cd on the guinea grass.

Conclusions

The supply of S reduces the phytotoxicity caused by Cd to guinea grass, especially during the regrowth of the plant, when the concentration of Cd is higher because of the transport from roots to shoots. Tanzania guinea grass showed to be very promising for phytoextraction of Cd due to its high mass production, even when Cd was largely available in the nutrient solution.

     

Hematological and splenic Doppler ultrasonographic changes in dogs sedated with acepromazine or xylazine

Objective

To evaluate the onset and duration of hematological changes and the use of Doppler ultrasound (spleen) in dogs sedated with acepromazine or xylazine.

Acute and Chronic Effects of Three Pharmaceutical Drugs on the Tropical Freshwater Cladoceran Ceriodaphnia silvestrii

Water, Air, & Soil Pollution - Phosphorus (P) is an essential element for all living organisms, and plays a major role in many physiological processes. However, in recent years, excessive...     

LOW-FIELD MAGNETIC RESONANCE IMAGING OF BEAGLE BRAIN WITH A DEDICATED RECEIVER COIL

A specially designed radio frequency receiver coil was used in a low-field-strength (0.1 T) magnetic resonance imager to improve the image quality of the Beagle brain. The aim was to obtain better distinction of anatomic details with a better signal-to-noise ratio in shorter imaging time. The spin-echo (TR/TE = 1200/100; TR is the repetition time and TE is the echo time in ms) brain images of three Beagles indicate that the new receiver coil can fulfill these goals.     

Phase velocities of rayleigh waves in the MELT experiment on the east pacific rise

The phase velocities of Rayleigh waves increase more rapidly with distance from the East Pacific Rise (EPR) axis than is predicted by models of conductive cooling of the lithosphere. Low velocities near the axis are probably caused by partial melt at depths of 20 to 70 kilometers in a zone several hundred kilometers wide. The lowest velocities are offset to the west of the EPR. Wave propagation is anisotropic; the fast direction is approximately perpendicular to the ridge, parallel to the spreading direction. Anisotropy increases from a minimum near the axis to 3 percent or more on the flanks.     

Predatory dinosaur remains from madagascar: implications for the cretaceous biogeography of gondwana

Recent discoveries of fossil vertebrates from the Late Cretaceous of Madagascar include several specimens of a large theropod dinosaur. One specimen includes a nearly complete and exquisitely preserved skull with thickened pneumatic nasals, a median frontal horn, and a dorsal projection on the parietals. The new materials are assigned to the enigmatic theropod group Abelisauridae on the basis of a number of unique features. Fossil remains attributable to abelisaurids are restricted to three Gondwanan landmasses: South America, Madagascar, and the Indian subcontinent. This distribution is consistent with a revised paleogeographic reconstruction that posits prolonged links between these landmasses (via Antarctica), perhaps until late in the Late Cretaceous.     

Climate-Ocean Variability and Ecosystem Response in the Northeast Pacific

The role of climatic variation in regulating marine populations and communities is not well understood. To improve our knowledge, the sign, amplitude, and frequency of climatic and biotic variations should be compared as a necessary first step. It is shown that there have been large interannual and interdecadal sea-surface temperature changes off the West Coast of North America during the past 80 years. Interannual anomalies appear and disappear rather suddenly and synchronously along the entire coastline. The frequency of warm events has increased since 1977. Although extensive, serial, biological observations are often incomplete, it is clear that climate-ocean variations have disturbed and changed our coastal ecosystems.