Involvement of glutathione metabolism in Eichhornia crassipes tolerance to arsenic.

Aquatic macrophytes are potentially useful for phytoremediation programmes in environments contaminated by arsenic (As). Biochemical and physiological modification analyses in different plant parts are important to understand As tolerance mechanisms. The objective was to evaluate glutathione metabolism in leaves and roots of Eichhornia crassipes (Mart.) Solms treated to As. Specimens of E. crassipes were cultured for 3 days in Clark's nutrient solution containing 7 µm As. The enzymes ATP sulphurylase (ATPS), glutathione reductase (GR), glutathione peroxidase (GSH-Px), glutathione sulphotransferase (GST) and γ-glutamylcysteine synthetase (γ-ECS) activity, glutathione content, total protein and non-protein thiols were evaluated. The ATPS activity increased in roots. GR activity in leaves and GSH-Px in roots were lower. GST activity was higher in roots and lower in leaves, and γ-ECS activity was higher in leaves. Glutathione levels were lower, total thiol levels were higher and non-protein levels did not change in E. crassipes leaves and roots. Exposure to As increased enzyme activity involved with sulphur metabolism, such as ATPS. Higher GR activity and lower GSH-Px indicate increased glutathione conjugation to As due to increased GSH availability. The higher GST activity indicates its participation in As detoxification and accumulation through As GSH conjugation. Changes in glutathione and thiol levels suggest high phytochelatin synthesis. In conclusion, the increments in ATPS, GR, GST and γ-ECS activity indicate that these enzymes are involved in GSH metabolism and are part of the E. crassipes As detoxification mechanism.

Mechanical removal (epidermal scarification) of pododermatitis injuries reduces the presence of both inflammatory tissue and its associated microbiota in broiler feet.

Chicken feet have become an important commodity in the international market, representing a significant portion of poultry products exported by countries such as Brazil and the USA. However, the presence of pododermatitis in the footpad is an important barrier to exportation, since importing countries do not accept injured feet or allow the use of automatic equipments to remove the affected tissue. The objective of this research was to evaluate the impact of using an automatic equipment to remove injuries of pododermatitis on histological and microbiological traits of broiler feet processed according to commercial practices. A total of 240 broiler feet obtained from a commercial processing plant was visually classified according to the degree of pododermatitis and distributed in a 4 × 2 factorial arrangement, totalizing eight treatments with 30 replications. Factors were feet classification (1 to 4) and injury removal (yes or no). Feet were sampled for microbiological and histological analysis before and after the mechanical removal of pododermatitis injuries by an automatic machine that promoted footpad epidermal scarification. No significant interaction between feet classification and injury removal was detected for any of the analyzed variables. Also, no significant effect of feet classification was detected on aerobic plate counts, total coliforms and Escherichia coli. Feet inflammation score tended to increase (P = 0.06) according to the downgrading of feet classification, but the mechanical removal of pododermatitis injuries reduced feet inflammation score (P < 0.01), total coliform counts (P = 0.01), and E. coli (P = 0.01) independently of feet classification. Together, these results demonstrate the efficacy of the automatic equipment in removing both the inflammatory tissue and its associated microbiota in broiler feet affected by pododermatitis. Therefore, in addition to the already authorized use of blades, the use of automatic equipments for epidermal scarification in the processing of broiler feet deserves further consideration by the regulatory agencies.