Silicon acquisition and accumulation in plant and its significance for agriculture

Although silicon（Si） is ubiquitous in soil and plant, evidence is still lacking that Si is essential for higher plants. However, it has been well documented that Si is beneficial for healthy growth of many plant species. Si can promote plant mechanical strength, light interception, as well as resistance to various forms of abiotic and biotic stress, thus improving both yield and quality. Indeed, application of Si fertilizer is a rather common agricultural practice in many countries and regions. As the beneficial effects provided by Si are closely correlated with Si accumulation level in plant, elucidating the possible mechanisms of Si uptake and transport in plants is extremely important to utilize the Si-induced beneficial effects in plants. Recently, rapid progress has been made in unveiling molecular mechanisms of Si uptake and transport in plants. Based on the cooperation of Si influx channels and efflux transporters, a model to decipher Si uptake, transport and distribution system in higher plants has been developed, which involves uptake and radial transport in root, xylem and inter-vascular transport and xylem unloading and deposition in leaf. In this paper, we overviewed the updated knowledge concerning Si uptake, transport and accumulation and its significance for the major crops of agricultural importance and highlighted the further research needs as well.

Gender Differences in Pulmonary Inflammation Following Systemic Cadmium Administration in Rats

Objective To examine the presence of gender differences in pulmonary inflammation evoked by acute systemic cadmium administration in rats. Methods Presence of basic indicators of lung inflammation （inflammatory cytokine lung content, leukocyte infiltration and activity of cells recovered from lungs by enzyme digestion） was analyzed and compared in animals of the two sexes. Results Intraperitoneal administration of cadmium （1.0 mg/kg） resulted in higher cadmium content in lungs of female rats. Higher tumor necrosis factor （TNF） content was noted in lung homogenates of male rats, while interleukin-6 （IL-6） content was slightly, but signifaicantly greater in lungs of female rats. Increased leukocyte infiltration was observed in lungs of male rats, mainly due to neutrophils. Increased responsiveness to phorbol myristate acetate （PMA） stimulation was noted in cells recovered from lungs of male rats. Rise in intracellular content of myeloperoxidase （MPO） was noted in lung cells from cadmium-treated rats of both sexes, but higher in cells from male rats. Conclusion Presented data documented a more intense pulmonary inflammatory response to systemic cadmium administration in males, with higher IL-6 levels in lungs of female individuals. These sex differences in proinflamatory activity of cadmium in lungs should be taken into consideration in studying the remote toxicity of this heavy metal.