Drought stress,mercuric chloride,andβ-mercaptoethanol effects on hydraulic characteristics of three cultivars of wolfberry(Lycium chinense)

In order to further understand the effects of drought stress on hydraulic characteristics and the relationship between hydraulic conductivity and aquaporins or water channels of root systems of three wolfberry cultivars(Lycium chinense Mill.),hydraulic conductivity of 2-yearold pot-grown seedlings was measured under drought stress,rewatering,and treatment with exogenous mercuric chloride andβ-mercaptoethanol.Under moderate and severe drought stress levels,the most significant decrease of hydraulic conductivity was 37.3%and 24.0%,respectively,in the‘Ningqi 5’cultivar compared with the nonstressed control.After rewatering,the rate of recovery in specific conductivity was most rapid in the‘Mengqi 1’cultivar,at 0.058 and 0.072 kg MPa^-1 m^-2 s^-1 h^-1 under moderate and severe drought stress levels,respectively.The‘Mengqi 1’cultivar had the highest recovery degree of hydraulic conductivity under two concentrations ofβ-ME(500 or 1000 lmol L^-1),reaching 82.4%and 88.5%,respectively,of the initial conductivity.The adaptive capacity of hydraulic conductivity in the‘Ningqi 5’cultivar was weaker than in the‘Ningqi 1’and‘Mengqi 1’cultivars under drought stress.The recovery capacity of hydraulic conductivity in‘Mengqi 1’cultivar was stronger than the‘Ningqi 1’and‘Ningqi 5’cultivars after rewatering.Aquaporins of the‘Ningqi 1’cultivar root systems had the highest binding affinity with mercuric chloride,which was the most likely cause in the decrease in hydraulic conductivity,whereas aquaporins of‘Mengqi 1’root systems had the weakest binding affinity.The inhibitory effect of mercuric chloride was readily eliminated byβ-mercaptoethanol in the‘Mengqi 1’cultivar.The hydraulic characteristics of this cultivar were more sensitive to drought,mercuric chloride andβ-mercaptoethanol than the other cultivars.

Red onion extract(Allium cepa L.)supplementation improves redox balance in oxidatively stressed rats

Onions,consumed worldwide,are a good source of dietary phytochemicals with proven antioxidant properties.Catechin and quercetin are the most common and widely consumed flavonoids.The present study aimed to investigate the possible protective effect of onion extract as well as flavonoids(catechin and quercetin)on rats subjected to oxidative stress by mercuric chloride(HgCl2)treatment.Experiments were conducted on rat erythrocytes,which are a good model system to study oxidative stress.Results show that the oxidative stress induced by HgCl2 in Wistar rats resulted in substantially increased erythrocyte lipid peroxidation and higher activity of red cell plasma membrane redox system(PMRS)along with corresponding decrease in the intracellular reduced glutathione and antioxidant activity.Onion extract supplementation significantly(P<0.05)attenuated these adverse effects of HgCl2.Flavonoid supplementation resulted in a slightly higher antioxidant response compared to onion extract.We conclude that supplementation of these flavonoids results in normalization of erythrocyte PMRS activity which provides onion(rich in quercetin),a novel mechanism to exert its antioxidant effect against HgCl2-induced oxidative stress in rat erythrocytes in vivo.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Combined Effects of Cd and Hg on Liver and Kidney Histology and Function in Wistar Rats

The present study was performed in order to discern the effects of combined exposure to cadmium and mercury on liver function and histopathological alterations in male adult Wistar rats. In the present investigation, cadmium (100 mg/l) and mercury (25 mg/l) were administered orally for 10 weeks separately or in combination. The rational for studying cadmium and mercury is that both of these metals are encountered frequently in the same contaminated areas. In liver, the activities of serum alanine aminotransferase (ALT) and aspartate amino tranferase (AST) increased significantly in the cadmium (Cd) and mercury (Hg) alone or in combination (Cd + Hg) compared to the control suggesting that both cadmium and mercury cause hepatotoxicity spatially when co-administrated. We noted an increase in serum lactate dehydrogenase (LDH) activity in Cd and combined Cd + Hg treated groups while it decreased in Hg treated group. There was no statistically significant change in the level of total bilirubilin. Serum urea concentration showed a significant increase in the Cd and Hg groups compared to the control group. However an increase in serum creatinine concentration was noted only in the combined treated rats showing that renal insufficiency is more serious in the co-exposed group. Light microscopic examination indicated severe histological changes in the two organs under Cd and mercury influence. Results of the present investigation clearly showed that mercury has profound effects of hepatic handling of cadmium (synergistic effect) as shown by histological and biochemical results. Moreover, we observed a antagonist effect between these two toxic metals on kidney markers such as urea.

100 years of high GEM concentration in the Central Italian Herbarium and Tropical Herbarium Studies Centre(Florence,Italy)

Up to 1980 s,the most used preservative for herbaria specimens was HgCl2,sublimating at ambient air conditions;ionic Hg then reduces to Hg0(gaseous elemental mercury,GEM)and diffuses throughout poor ventilated environments.High GEM levels may indeed persist for decades,representing a health hazard.In this study,we present new GEM data from the Central Italian Herbarium and Tropical Herbarium Studies Centre of the University of Florence(Italy).These herbaria host one of the largest collection of plants in the world.Here,HgCl2 was documented as plant preservative up to the 1920 s.GEM surveys were conducted in July 2013 and July and December 2017,to account for temporal and seasonal variations.Herbaria show GEM concentrations well above those of external locations,with peak levels within specimen storage cabinets,exceeding 50,000 ng/m3.GEM concentrations up to^7800 ng/m3 were observed where the most ancient collections are stored and no ventilation systems were active.On the contrary,lower GEM concentrations were observed at the first floor.Here,lower and more homogeneously distributed GEM concentrations were measured in 2017 than in 2013 since the air-conditioning system was updated in early2017.GEM concentrations were similar to other herbaria worldwide and lower than Italian permissible exposure limit of 20,000 ng/m3(8-hr working day).Our results indicate that after a century from the latest HgCl2 treatment GEM concentrations are still high,i.e.,the treatment itself is almost irreversible.Air conditioning and renewing is probably the less expensive and more effective method for GEM lowering.

Hepatic endogenous defense potential of propolis after mercury intoxication

Exposure to mercuric chloride(HgCl2;5 mg kg–1 body weight;i.p.)induced oxidative stress in mice and substantially increased lipid peroxidation(LPO)and oxidized glutathione(GSSG)levels,decreased the level of reduced glu-tathione(GSH)and various antioxidant enzymes in liver and also increased the activities of liver marker enzymes in serum.Therapy with propolis extract,a resinous wax-like beehive product(200 mg kg–1 orally,after mercury administration),for 3 days inhibited LPO and the formation of GSSG and increased the level of GSH in the liver.Release of serum transaminases,alkaline phosphatase,lactate dehydrogenase and-glutamyl transpeptidase were significantly restored after propolis treatment.The activities of antioxidant enzymes,that is,superoxide dismutase,catalase,glutathione-S-transferase and glucose-6-phosphate dehydrogenase,were also concomitantly restored towards normal levels after propolis administration.These observations clearly demonstrate that propolis treatment augments antioxidant defense against mercury-induced toxicity and provide evidence that propolis has therapeutic potential as a hepatoprotective agent.