Hemodialysis removes uremic toxins that alter the biological actions of endothelial cells

Chronic kidney disease is linked to systemic inflammation and to an increased risk of ischemic heart disease and atherosclerosis. Endothelial dysfunction associates with hypertension and vascular disease in the presence of chronic kidney disease but the mechanisms that regulate the activation of the endothelium at the early stages of the disease, before systemic inflammation is established remain obscure. In the present study we investigated the effect of serum derived from patients with chronic kidney disease either before or after hemodialysis on the activation of human endothelial cells in vitro, as an attempt to define the overall effect of uremic toxins at the early stages of endothelial dysfunction. Our results argue that uremic toxins alter the biological actions of endothelial cells and the remodelling of the extracellular matrix before signs of systemic inflammatory responses are observed. This study further elucidates the early events of endothelial dysfunction during toxic uremia conditions allowing more complete understanding of the molecular events as well as their sequence during progressive renal failure.     

Enhancing planting stock quality of Italian cypress (Cupressus sempervirens L.) by pre-cultivation in mini-plugs

Native species are important in ecological restoration of degraded forest ecosystems provided that their ecological engineering potential is exploited. Their failure to get established is usually due to the use of low-quality planting stock and adverse site conditions. Mini-plug transplants are a relatively new and promising production system in the forest nursery area. Objectives of our study were the evaluation of seedling production of Italian cypress (Cupressus sempervirens) in mini-plug containers, the study of the effect of mini-plug density and substrate on planting stock quality, the comparison of the performance between mini-plug seedlings and the standard planting stock produced by Greek nurseries and the evaluation of physiological and morphological variables as predictive indicators of Italian cypress field performance. Our results showed that cypress seedlings could be produced using the mini-plug technique, resulting in higher quality seedlings than the standard stock type. Pre-cultivation of cypress seedlings under favorable conditions for a period of 5 weeks using peat and high mini-plug densities (1800–3500 mini-plugs m^?2) could be recommended. Grading of seedlings by using both easily measured morphological variables (root length, leaf area, root and shoot dry weight) and physiological tests, such as shoot electrolyte leakage, may improve survival and transplanting success. It is concluded that mini-plugs can serve ecological restoration of degraded forest ecosystems more efficiently than standard planting stock.     

Spermidine exodus and oxidation in the apoplast induced by abiotic stress is responsible for H2O2 signatures that direct tolerance responses in tobacco

Polyamines (PAs) exert a protective effect against stress challenges, but their molecular role in this remains speculative. In order to detect the signaling role of apoplastic PA-derived hydrogen peroxide (H2O2) under abiotic stress, we developed a series of tobacco (Nicotiana tabacum cv Xanthi) transgenic plants overexpressing or downregulating apoplastic polyamine oxidase (PAO; S-pao and A-pao plants, respectively) or downregulating S-adenosyl-l-methionine decarboxylase (samdc plants). Upon salt stress, plants secreted spermidine (Spd) into the apoplast, where it was oxidized by the apoplastic PAO, generating H2O2. A-pao plants accumulated less H2O2 and exhibited less programmed cell death (PCD) than did wild-type plants, in contrast with S-pao and samdc downregulating plants. Induction of either stress-responsive genes or PCD was dependent on the level of Spd-derived apoplastic H2O2. Thus, in wild-type and A-pao plants, stress-responsive genes were efficiently induced, although in the latter at a lower rate, while S-pao plants, with higher H2O2 levels, failed to accumulate stress-responsive mRNAs, inducing PCD instead. Furthermore, decreasing intracellular PAs, while keeping normal apoplastic Spd oxidation, as in samdc downregulating transgenic plants, caused enhanced salinity-induced PCD. These results reveal that salinity induces the exodus of Spd into the apoplast, where it is catabolized by PAO, producing H2O2. The accumulated H2O2 results in the induction of either tolerance responses or PCD, depending also on the levels of intracellular PAs.     

Characterization of the biodegradation,bioremediation and detoxification capacity of a bacterial consortium able to degrade the fungicide thiabendazole

Thiabendazole (TBZ) is a persistent fungicide used in the post-harvest treatment of fruits. Its application results in the production of contaminated effluents which should be treated before their environmental discharge. In the absence of efficient treatment methods in place, biological systems based on microbial inocula with specialized degrading capacities against TBZ could be a feasible treatment approach. Only recently the first bacterial consortium able to rapidly transform TBZ was isolated. This study aimed to characterize its biodegradation, bioremediation and detoxification potential. The capacity of the consortium to mineralize ¹⁴C-benzyl-ring labelled TBZ was initially assessed. Subsequent tests evaluated its degradation capacity under various conditions (range of pH, temperatures and TBZ concentration levels) and relevant practical scenarios (simultaneous presence of other postharvest compounds) and its bioaugmentation potential in soils contaminated with increasing TBZ levels. Finally cytotoxicity assays explored its detoxification potential. The consortium effectively mineralized the benzoyl ring of the benzimidazole moiety of TBZ and degraded spillage level concentrations of the fungicide in aqueous cultures (750 mg L^?1) and in soil (500 mg kg^?1). It maintained its high degradation capacity in a wide range of pH (4.5–7.5) and temperatures (15–37 °C) and in the presence of other pesticides (ortho-phenylphenol and diphenylamine). Toxicity assays using the human liver cancer cell line HepG2 showed a progressive decrease in cytotoxicity, concomitantly with the biodegradation of TBZ, pointing to a detoxification process. Overall, the bacterial consortium showed high potential for future implementation in bioremediation and biodepuration applications.