Cadmium (Cd) is a hazardous heavy metal whose concentrations have been increasing in Brazilian soils, largely due to mining activities. Eucalyptus species are widely planted in Brazil to produce raw materials, and the confirmation of their phytoremediation potential would link their economic and environmental roles. We examined the Cd-tolerance of Eucaliptus camaldulenses Dehnh and the anatomical and physiological features associated with that capacity. Plants were grown under greenhouse conditions in nutrient solutions with increasing concentrations of Cd (0, 15, 25, 45, 90 μmol m -3 ). Shoot biomass production was less sensitive to the phytotoxic effects of cadmium than root biomass production due to low Cd transport rates from roots to shoots. Increases in epidermal and endodermal thickness, changes in the vascular conductive elements of the roots, as well as differential nutrient distributions between roots and shoots are features of Cd tolerance in this species. The Cd tolerance of E. camaldulenses and its high biomass production support its potential use in Cd phytoremediation programs.

Due to similarities in their chemical behaviors, studies examining interactions between arsenic (As)--in special arsenate--and phosphorus (P) are important for better understanding arsenate uptake, toxicity, and accumulation in plants. We evaluated the effects of phosphate addition on plant biomass and on arsenate and phosphate uptake by Anadenanthera peregrina, an important Brazilian savanna legume. Plants were grown for 35 days in substrates that received combinations of 0, 10, 50, and 100 mg kg(-1) arsenate and 0, 200, and 400 mg kg(-1) phosphate. The addition of P increased the arsenic-phytoremediation capacity of A. peregrina by increasing As accumulation, while also alleviating As-induced oxidative stress. Arsenate phytotoxicity in A. peregrina is due to lipid peroxidation, but not hydrogen peroxide accumulation. Added P also increased the activity of important reactive oxygen species-scavenging enzymes (catalase and ascorbate peroxidase) that help prevent lipid peroxidation in leaves. Our findings suggest that applying P represents a feasible strategy for more efficient As phytoremediation using A. peregrina.

Effects of adding different concentrations of melatonin (10 , 10 and 10 M) to maturation (Experiment 1; Control, IVM + 10 , IVM + 10 , IVM + 10 ) and culture media (Experiment 2; Control, IVC + 10 , IVC + 10 , IVC + 10 ) were evaluated on in vitro bovine embryonic development. The optimal concentration of melatonin (10 M) from Experiments 1-2 was tested in both maturation and/or culture media of Experiment 3 (Control, IVM + 10 , IVC + 10 , IVM/IVC + 10 ). In Experiment 1, maturated oocytes from Control and IVM + 10 treatments showed increased glutathione content, mitochondrial membrane potential and percentage of Grade I blastocysts (40.6% and 43%, respectively). In Experiment 2, an increase in the percentage of Grade I blastocysts was detected in IVC + 10 (43.5%; 56.7%) and IVC + 10 (47.4%; 57.4%). Moreover, a lower number and percentage of apoptotic cells in blastocysts were observed in the IVC + 10 group compared to Control (3.8 ± 0.6; 3.6% versus 6.1 ± 0.6; 5.3%). In Experiment 3, the IVC + 10 treatment increased percentage of Grade I blastocysts with a lower number of apoptotic cells compared to IVM/IVC + 10 group (52.6%; 3.0 ± 0.5 versus 46.0%; 5.4 ± 1.0). The IVC + 10 treatment also had a higher mRNA expression of antioxidant gene (SOD2) compared to the Control, as well as the heat shock protein (HSPB1) compared to the IVM + 10 . Reactive oxygen species production was greater in the IVM/IVC + 10 treatment group. In conclusion, the 10 M concentration of melatonin and the in vitro production phase in which it is used directly affected embryonic development and quality.

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