Crosslinked Chitosan Films Supplemented with Randia sp. Fruit Extract.

This work proposes the development of a polymer film made up of affordable components for its use as a healthcare material. Chitosan, itaconic acid, and Randia capitata fruit extract (Mexican variation) are the unique ingredients of this biomaterial prospect. Chitosan (from crustacean chitin) is crosslinked with itaconic acid, and in situ added R. capitata fruit extract in a one-pot reaction carried out in water as the sole solvent. Structurally, the film formed is an ionically crosslinked composite characterized by IR spectroscopy and thermal analysis (DSC and TGA); cell viability was also performed in vitro using fibroblasts BALB/3T3. Dry and swollen films were analyzed to determine affinity and stability in water. This chitosan-based hydrogel is designed as a wound dressing due to the combined properties of the chitosan with R. capitata fruit extract, which has potential as bioactive material due to its properties in epithelial regeneration.

Procedure for Estimating the Tolerance and Accumulation of Heavy Metals Using Plant Cell Cultures.

The tolerance index (TI) and the bioaccumulation factor (BF) for the estimation of accumulation and tolerance of different heavy metals in cell suspension cultures are reviewed. Procedures for measuring these parameters are described for the purposes of phytoremediation research.

Tolerance, arsenic uptake, and oxidative stress in Acacia farnesiana under arsenate-stress.

Acacia farnesiana is a shrub widely distributed in soils heavily polluted with arsenic in Mexico. However, the mechanisms by which this species tolerates the phytotoxic effects of arsenic are unknown. This study aimed to investigate the tolerance and bioaccumulation of As by A. farnesiana seedlings exposed to high doses of arsenate (AsV) and the role of peroxidases (POX) and glutathione S-transferases (GST) in alleviating As-stress. For that, long-period tests were performed in vitro under different AsV treatments. A. farnesiana showed a remarkable tolerance to AsV, achieving a half-inhibitory concentration (IC50) of about 2.8 mM. Bioaccumulation reached about 940 and 4380 mg As·kg(-1) of dry weight in shoots and roots, respectively, exposed for 60 days to 0.58 mM AsV. Seedlings exposed to such conditions registered a growth delay during the first 15 days, when the fastest As uptake rate (117 mg kg(-1) day(-1)) occurred, coinciding with both the highest rate of lipid peroxidation and the strongest up-regulation of enzyme activities. GST activity showed a strong correlation with the As bioaccumulated, suggesting its role in imparting AsV tolerance. This study demonstrated that besides tolerance to AsV, A. farnesiana bioaccumulates considerable amounts of As, suggesting that it may be useful for phytostabilization purposes.

Effect of a saprophytic fungus on the growth and the lead uptake, translocation and immobilization in Dodonaea viscosa.

Phytoremediation is a feasible alternative to remediate soils polluted with toxic elements, which can be enhanced by manipulating plant-microbe interactions. Regarding this, free-living saprophytic fungi that interact beneficially with roots have been scarcely studied. Thus, the aim of this study was to assess the effect of a saprophytic fungus, Lewia sp., on the plant growth and the ability of Dodonaea viscosa to phytoaccumulate or phytostabilize soluble and insoluble sources of lead in a solid support. The growth of D. viscosa was influenced by both Pb and Lewia sp. While seedlings exposed to Pb showed a decrease in biomass production, in seedlings grown without Pb the biomass was stimulated by Lewia sp. The fungus strongly stimulated the weight-to-length ratio in roots. Regardless of the treatment, D. viscosa accumulated 4.4-6.5 times more Pb in roots than in shoots, conducting to low translocation factors (< 0.2). The presence of Lewia sp. significantly improved Pb accumulation, achieving high bioconcentration factors (> 22), which was attributed to an increased bioavailability and uptake of Pb due to the fungus. This study demonstrated that Lewia sp. could improve Pb-phytostabilization by D. viscosa in soils polluted with soluble and insoluble forms of Pb.

Increased mesquite gum formation in nodal explants cultures after treatment with a microbial biomass preparation.

Prosopis laevigata nodal explants cultures were established in Murashige and Skoog medium. Simultaneously these cultures were subjected to stress with biotic elicitors and an environmental factor (temperature increase to promote heat stress) in order to promote and increase exuded mesquite gum production. The biotic elicitors were: Aspergillus nidulans and Pseudomonas pseudoalcaligenes both used in concentrations of 10, 20 and 30 mg, whereas the environmental condition was different incubation temperatures (25, 35 and 40 degrees C). The greatest gum production (approximately 13 mg of pooled gum from 100 explants after 14 days incubation) took place when the culture medium was added 10, 20 and 30 mg of autoclaved fungal mycelium of A. nidulans or 30 mg of autoclaved bacterial biomass of P. pseudoalcaligenes in combination with an incubation temperature of 35 degrees C. These treatments were non-significantly different among themselves (P < 0.05), but were significantly different to the rest of the treatments (P > 0.05).