Toxicity evaluation and preparation of CoWO4 nanoparticles towards microalga Dunaliella salina.

The increasing use of nanoparticles and their many applications increases the likelihood of their presence in the environment. This possibility of presence necessitates the study of the effect of these substances on aquatic species. In this research, CoWO4 nanoparticles were synthesized by the ultrasonic method. Various conditions in the synthesis process were investigated to obtain the appropriate size of the nanoparticles. After selecting the optimum particles, these nanoparticles were used to investigate their effect on the growth of Dunaliella salina. For this purpose, the algal cells were subjected to three different concentrations of nanoparticles (15, 30, and 60 mg/L). The study results on algae growth parameters showed that these parameters depend on the value of nanoparticles. At 15 and 30 mg/L concentrations of the nanoparticles, numbers of cells, specific growth, biomass, and pigments showed a significant boost compared to the mentioned parameters of the control treatment. Measurement of malondialdehyde (MDA) showed that this parameter was directly related to the increase in the concentration of nanoparticles. At 60 mg/L of the nanoparticles, the MDA level was higher than the control and other treatments. This increase reflects the destructive effect of the nanoparticles on algal cells. Finally, the results showed that algae could be useful for studying the environmental effects of nanoparticles and their safety.

Central role of 70-kDa heat shock protein in adaptation of plants to drought stress.

The 70-kDa heat shock proteins (HSP70s) are a conserved class of chaperones that play critical roles during the normal life cycle of plants. HSP70s are particularly involved in the regulation of biotic and abiotic stress responses. In this paper, the potential roles of this protein were investigated. A reverse genetic approach was employed for transient silencing of hsp70 gene in tomato (Solanum lycopersicum L.) to evaluate different growth and physiological parameters under normal conditions and during the response to drought stress. A combined ANOVA (analysis of variance) and HCA (hierarchical clustering analysis) showed that hsp70 silencing led to severe growth retardation and mortality, significant membrane damage and leakage, decline in relative water content, low rate of pigment accumulation, and reduced antioxidant enzyme activity under normal and drought stress conditions. Among the different parameters, proline was the only trait that was unaffected by gene silencing and accumulated by similar amounts to that of nonsilent plants. In conclusion, HSP70 played critical roles in maintaining the cellular homeostasis of plants during adaptation to drought and under normal plant life conditions. It was speculated that proline was, to some extent, involved in improving the loss of protein folding or function resulting from HSP70 deficiency, and played a crucial role in the adaptation of plants on exposure to stress.