Sap flow and water use in African baobab (Adansonia digitata L.) seedlings in response to drought stress

The African baobab (Adansonia digitata L.) is an important multi-purpose fruit tree with high potential for domestication in drier Africa. Although adult individuals are well-known to be drought resistant, only little has been reported on how young baobab trees can survive drought. Therefore, the aim of this study was to examine short-term soil drought effects on water relations of baobab seedlings. Baobab seedlings used a limited amount of stored water to buffer daily water deficits (~ 8.5 g d^− 1), which contributed up to only ~ 17.5% of daily water use and ~ 6% of total plant water. Under drought, a strong reduction in stomatal conductance (~ 85%) resulted in a midday leaf water potential of − 1 MPa and zero stem sap flow followed by significant leaf loss. Plant anatomy evidenced the presence of water storage tissues and the vulnerability to xylem embolism. The taproot was the most important plant part for water storage (68% of total plant water), suggesting root-succulence rather than stem-succulence. When drought intensified, limitation of leaf transpiration and/or root water uptake led to drought-enforced dormancy. Despite the large amounts of water stored in the taproot (~ 90%) and the stem (~ 75%), only a limited amount of stored water appeared to be used to sustain upper leaves and plant metabolism during the dormant period, and to facilitate recovery following water supply. Drought avoidance, conservative water use and the presence of internal stored water allow baobab seedlings to survive drought.     

Subcellular compartmentation of strontium and zinc in mulberry idioblasts in relation to phytoremediation potential

The cellular compartmentation of heavy metals was analyzed using mulberry leaves, in which CaCO₃-forming idioblasts are situated in the epidermal layer. Germinated mulberry seedlings were grown on hydroponic culture medium containing strontium (Sr), zinc (Zn), and cadmium (Cd) with and without supplemental calcium (Ca). After ten weeks of growth, toxic effects of these metals were assessed by measuring shoot length and chlorophyll content of leaves. Sr and Cd treatment at a higher dose (4 mM for Sr, 25 μM for Cd) resulted in signs of toxicity, whereas no distinct phytotoxicity was observed at 500 μM Zn. Elemental mapping of leaves using an energy-dispersive X-ray microanalysis system fitted to variable-pressure scanning electron microscope showed that Sr and Zn were preferentially accumulated in the idioblasts and Cd was not detected in any type of leaf cell. The deposition site of Sr was confined to cell wall sacs developing in idioblasts. The Sr sink capacity in leaves was more than 30 mg/g dry weight, which equaled the Ca sink capacity. Exposure of Sr + Ca led to the co-localization of Sr and Ca in the same cell wall sac, in which Ca and Sr deposition were each estimated to be 60–80 ng. The localization site of Zn was cell walls of a dome-shaped protrusion (cap) of idioblasts, together with silicon (Si) originating as a contaminant in tap water used for culturing. Mulberry idioblasts were unique in showing metal-dependent distribution to two subcellular sites (cell wall sac and cap region) of idioblasts. In conclusion, mulberry plant is a candidate for phytoremediation of radiostrontium because of their Sr-hyperaccumulating capacity with sufficient leaf biomass production.     

Zinc induced damage to kidney proximal tubular cells: Studies on chemical speciation leading to a mechanism of damage

This study was carried out to investigate whether zinc can potentiate renal toxicity using monolayer cultures of kidney proximal tubular cells and if so to establish the chemical species and the mechanism involved.MethodsZinc was prepared as the citrate complex at pH 7.4 in phosphate buffered saline. Monolayers of kidney proximal tubular cells under standard cell culture conditions were exposed to zinc concentrations of 0, 5 10, 20, 50 and 100 μmol/L. To assess cellular damage, thiazol blue (MTT) uptake, NAG and LDH release, DAPI staining and Tunel assay were used. Cytoprotective agents: trolox, cysteine, glutathione, ascorbic acid and sodium selenite were used to investigate if the damage was reversible.ResultsIncubation of kidney cells with zinc citrate showed a dose related reduction in cell viability (p < 0.005) associated with cellular uptake of zinc ions. After 24 h incubation with 100 μmol/L Zn citrate, NAG release was not significantly different compared to the control whereas LDH increased 3 fold. DAPI staining showed apoptotic bodies within the cells confirmed by Tunel assay using flow cytometry. Electron microscopy showed significant morphological changes including loss of brush border, vacuolated cytoplasm and condensed nuclei. Trolox almost completely (>85 ± 5%) and sodium selenite partially recovered (40 ± 4%) the viability of cells exposed to Zn but no protection was observed with other cytoprotectants, e.g. glutathione, cysteine or ascorbic acid.In conclusion zinc can induce damage to kidney cells by a mechanism dependent on zinc ions entering the cell, binding to the cell organelles and disrupting cellular processes rather than damage initiated by free radical and ROS production.     

Lead,zinc, cadmium hyperaccumulation and growth stimulation in Arabis paniculata Franch

Metal hyperaccumulation is of great interest in recent years because of its potential application for phytoremediation of heavy metal contaminated soils. In this study, a field survey and a hydroponic experiment were conducted to study the accumulation characteristics of lead (Pb), zinc (Zn) and cadmium (Cd) in Arabis paniculata Franch., which was found in Yunnan Province, China. The field survey showed that the wild population of A. paniculata was hyper-tolerant to extremely high concentrations of Pb, Zn and Cd, and could accumulate in shoots an average level of 2300 mg kg^?1 dry weight (DW) Pb, 20,800 mg kg^?1 Zn and 434 mg kg^?1 Cd, with their translocation factors (TFs) all above one. Under the hydroponic culture, stimulatory effects of Pb, Zn and Cd on shoot dry biomass were noted from 24 to 193 μM Pb, 9 to 178 μM Cd and all Zn supply levels in nutrient solution, while the effects were not obvious in the roots. Chlorophyll concentrations in Pb, Zn and Cd treatments showed an inverted U-shaped pattern, consistent with the change of plant biomass. Pb, Zn and Cd concentrations in the shoots and roots increased sharply with increasing Pb, Zn and Cd supply levels. They reached > 1000 mg kg^?1 Pb, 10,000 mg kg^?1 Zn and 100 mg kg^?1 Cd DW in the 24 μM Pb, 1223 μM Zn and 9 μM Cd treatment, respectively, in which the plants grew healthy and did not show any symptoms of phytotoxicity. The TFs of Zn were basically higher than one and the amount of Zn taken by shoots ranged from 78.7 to 90.4% of the total Zn. However, the TFs of Pb and Cd were well below one, and 55.0–67.5% of total Pb and 57.8–83.5% of total Cd was accumulated in the shoots. These results indicate that A. paniculata has a strong ability to tolerate and hyperaccumulate Pb, Zn and Cd. Meanwhile, suitable levels of Pb, Zn and Cd could stimulate the biomass production and chlorophyll concentrations of A. paniculata. Thus, it provides a new plant material for understanding the mechanisms of stimulatory effect and co-hyperaccumulation of multiple heavy metals.     

The effects of chelators on zinc levels in patients with thalassemia major

Zinc which is an essential element has very important effects on growth and immune system in patients with thalassemia major (TM). The effects of two oral iron chelator agents, desferrioxamine (DFO) and deferiprone (DFP), on zinc levels were investigated in previous studies and they were found to cause zinc deficiency. Zinc level alteration by the new chelator deferasirox (DFX) is not present in the literature. The aim of this study was to examine the effects of different oral chelators on serum and urine zinc levels in TM patients. Zinc levels are compared in the patients who received different chelators: only DFX, combined chelation with DFO plus DFP and the healthy control group. A total of 56 patients with TM were involved in this study: 39 patients received only DFX and 17 patients were given combined treatment DFO + DFP between August 2008 and August 2009. In addition, a control group was established from the healthy population. Blood was taken from all the patients for serum zinc levels and 24 hour-urine samples were collected for urine zinc levels. Serum zinc levels were found to be 64.8 ± 14.8 μg/dL in DFX group and 66.5 ± 15.1 μg/dL in DFO + DFP group. These levels were statistically lower than that in the control group (149 ± 54.3 μg/dL) (p < 0.05), but there was no statistically difference between the two different chelation groups (p > 0.05). The urine zinc levels of DFX and DFO + DFP group were 662.2 ± 428.2 μg/day and 1182.3 ± 980.3 μg/day respectively (p < 0.05). Urinary zinc excretion in the chelation groups (DFX and DFO + DFP) was significantly higher than the control group (395.1 ± 208.9 μg/day) (p < 0.05). As a conclusion, the new chelation agent, DFX, also leads to zinc deficiency, though its urinary zinc excretion is lower. New studies are required to examine the effects of DFX on zinc extensively. Zinc levels of patients with TM should be followed up regularly and zinc supply should be given at early ages.     

Time course analysis of ABA and non-ionic osmotic stress-induced changes in water status,chlorophyll fluorescence and osmotic adjustment in Arabidopsis thaliana wild-type (Columbia) and ABA-deficient mutant (aba2)

In the present study, we investigated time course changes of water status including relative water content (RWC), leaf osmotic potential (Ψ_Π), stomatal conductance (g_s), proline (Pro), chlorophyll fluorescence (F_v/F_m) and total chlorophyll content in the Arabidopsis thaliana under PEG-induced drought stress after exogenous ABA treatment. To a better explanation for the role of ABA in the water status of A. thaliana to drought stress, wild-type (Columbia) and ABA-deficient mutant (aba2) of A. thaliana were used in the present study. Moreover, three weeks old Arabidopsis seedlings were applied exogenously with 50 μM ABA and exposed to drought stress induced by 40% PEG8000 (−0.73 MPa) for 6 h, 12 h and 24 h (hours). Our findings indicate that RWC of wild-type and aba2 started to decrease in the first 12 h and 6 h of PEG-induced drought stress, respectively. However, exogenous treatment of 50 μM ABA increased their RWC under drought stress. On the other hand, while Ψ_Π of both genotypes started to decrease in the first 6 h of drought stress, these declines in Ψ_Π were prevented by ABA treatment under stress throughout the experiment; it was more pronounced in aba2 at 24 h. While the highest increase in g_s was obtained in aba2 after 24 h stress, ABA-induced highest decrease in g_s was obtained in the same genotype during 12 h, as compared to PEG-treated group alone. On the other hand, Pro content increased in all treatment groups of ABA-deficient mutant aba2 at 12 h and 24 h. However, Pro content in ABA + PEG treated aba2 plants was higher than in PEG- and ABA-treated plants alone at the end of the 24 h. Drought stress decreased F_v/F_m and total chlorophyll contents of both genotypes while 50 μM ABA alleviated these reductions during drought stress, as compared to PEG stressed plants. On the other hand, 50 μM ABA treatment alone did not create any remarkable effect on F_v/F_m and total chlorophyll contents.These findings indicate that exogenous ABA showed an alleviative effect against damage of drought stress on relative water content, osmotic potential, stomatal conductance, proline, chlorophyll fluorescence and total chlorophyll content of both genotypes during 24 h of drought stress treatment.     

Water relations and drought tolerance of young African tamarind (Tamarindus indica L.) trees

Tamarindus indica L. is an important multipurpose tree, indigenous to Africa, now introduced worldwide and known for its drought tolerance. The effects of drought on tamarinds, especially at seedling stage, are hardly investigated. However, this information is important for its conservation and domestication. In a growth chamber experiment we investigated the water relations of African tamarind seedlings under short-term soil drought stress. Initially tamarind seedlings can be considered as drought-tolerant at the expense of internal water storage reserves as they keep on transpiring (sap flow) and growing (diameter fluctuations). They finally spent 20% of their stem and root water storage reserves and experienced stem water potentials near − 3 MPa. Therefore, they can be classified as anisohydric. Their risk-taking behavior led to a high rate of seedling mortality (50%) because of whole plant hydraulic failure. They were not hydraulically efficient and they possessed low water storage capacity in stem and root (45%) due to high tissue density. When re-irrigated, remaining seedlings recovered slowly as a consequence of non-stomatal limitations and partial shoot dieback. Although tamarind seedlings show traits related to drought tolerance, we suggest that the species contains some water saving mechanisms. Contrasts with the co-occurring water-conserving tree species baobab (Adansonia digitata L.) are also discussed.     

Ectomycorrhiza affect architecture and nitrogen partitioning of beech (Fagus sylvatica L.) seedlings under shade and drought

The aim of this study was to investigate the influence of ectomycorrhizal fungi (EMF) on the architecture of and nitrogen (N) partitioning in young beech (Fagus sylvatica) plants in response to different light regimes and water deprivation. We hypothesized that EMF modify biomass partitioning and architecture of young beech plants by increased N uptake in comparison with non-mycorrhizal (NM) plants and that therefore, the drought responses of EM and NM plants diverge. We anticipated that full light-exposed plants were more drought tolerant due to improved water status and nutrition, whereas shade-acclimated EM plants were more drought susceptible because of decreased mycorrhizal colonization. To test these hypotheses seedlings were grown in native or sterilized forest soil. To avoid effects of soil pretreatment NM and EM plants were transplanted into sand-peat culture systems and exposed to shade, drought or the combination of both factors. Shade resulted in reduced root biomass production decreasing the root-to-shoot ratio. Mild drought stress (pre-dawn water potential [Ψ_pd] = −1.3 MPa) did not affect biomass partitioning. EMF colonization did not increase plant biomass, but had strong effects on root architecture: the numbers of root tips as well as the absolute and specific root lengths were increased because of formation of thin roots, especially in the diameter classes from 0.2 to 0.8 mm. In contrast to our expectation N uptake of well irrigated EM plants was not increased despite their larger potential for soil exploitation. Overall, EM plants exhibited higher amounts of carbon fixed per unit of N taken up than NM plants and shifted N partitioning towards the roots. Beneficial effects of EMFs were apparent under mild drought but the responses differed depending on the light availability: shaded EM plants showed a delay in the decrease of Ψ_pd; light exposed EM plants showed increased N uptake compared with NM beeches. These results indicate that EMFs are involved in mediating divergent responses of beech to drought depending on the light availability.     

Thiol-peptide level and proteomic changes in response to cadmium toxicity in Oryza sativa L. roots

In the present study, rice seedlings were exposed to a range of Cd concentrations (0.1 μM, 1 μM, 10 μM, 100 μM and 1 mM) for 15 days and a combination of different molecular approaches were used to evidence Cd effects and to assess the plants’ ability to counteract metal toxicity. At a macroscopical level, only the highest Cd concentration (1 mM) caused a complete plant growth inhibition, whereas the lowest concentrations seemed to stimulate growth. At genome level, the amplified fragment length polymorphism (AFLP) technique was applied to detect DNA sequence changes in root cells, showing that all the Cd concentrations induced significant DNA polymorphisms in a dose-dependent manner. Data also evidenced the absence of preferential mutation sites.Plant responses were analysed by measuring the levels of gluthatione (GSH) and phytochelatins (PCs), the thiol-peptides involved in heavy metal tolerance mechanisms. Results showed a progressive increase of GSH up to 10 μM of Cd treatment, whereas a significant induction only of PC₃ was detected in roots of plants exposed to 100 μM of Cd. As suggested by the proteome analysis of root tissues, this last concentration strongly induced the expression of regulatory proteins and some metabolic enzymes. Furthermore, the treatment with 10 μM of Cd induced changes in metabolic enzymes, but it mainly activated defence mechanisms by the induction of transporters and proteins involved in the degradation of oxidatively modified proteins.     

On-line preconcentration/determination of zinc from water,biological and food samples using synthesized chelating resin and flame atomic absorption spectrometry

An on-line flow injection pre-concentration-flame atomic absorption spectrometry method was developed to determine trace zinc in water (tap, dam, and well water), biological (hair and nail), and liver samples. As a solid phase extractant, a synthesized new chelating resin, poly(2-thiozylmethacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propane sulfonic acid) was used. The resin was characterized by Fourier transform infrared spectroscopy, elemental analysis, and surface area by nitrogen sorption. A pre-concentration factor of 40-fold for a sample volume of 12.6 mL was obtained by using the time-based technique. The detection limit for the pre-concentration method was found to be 2.2 μg L^?1. The precision (as RSD,%) for 10 replicate determinations at the 0.04 μg mL^?1 Zn concentration was 1.2%. The calibration graph using the pre-concentration system for zinc was linear with a correlation coefficient of 0.998 in the concentration range from 0.005 to 0.05 μg mL^?1. The applicability and accuracy of the developed method were estimated by the analysis spiked water, biological, liver samples (83–105%), and also certified reference material TMDA-70 (fortified lake water) and SPS-WW1 Batch 111-Wastewater. The results were in agreement with the certified values.     

Alleviating the adverse effects of NaCl stress in maize seedlings by pretreating seeds with salicylic acid and 24-epibrassinolide

The effects of bio-regulators salicylic acid (SA) and 24-epibrassinolide (EBL) as seed soaking treatment on the growth traits, content of photosynthetic pigments, proline, relative water content (RWC), electrolyte leakage percent (EC%), antioxidative enzymes and leaf anatomy of Zea mays L. seedlings grown under 60 or 120 mM NaCl saline stress were studied. A greenhouse experiment was performed in a completely randomized design with nine treatments [control (treated with tap water); 60 mM NaCl; 120 mM NaCl; 10^− 4 M SA; 60 mM NaCl + 10^− 4 M SA; 120 mM NaCl + 10^− 4 M SA; 10 μM EBL; 60 mM NaCl + 10 μMEBL or 120 mM NaCl + 10 μM EBL] each with four replicates. The results indicated that NaCl stress significantly reduced plant growth traits, leaf photosynthetic pigment, soluble sugars, RWC%, and activities of catalase (CAT), peroxidase (POX) as well as leaf anatomy. However, the application of SA or EBL mitigated the toxic effects of NaCl stress on maize seedlings and considerably improved growth traits, photosynthetic pigments, proline, RWC%, CAT and POX enzyme activities as well as leaf anatomy. This study highlights the potential ameliorative effects of SA or EBL in mitigating the phytotoxicity of NaCl stress in seeds and growing seedlings.     

Effect of arsenic on visible symptom and arsenic concentration in hydroponic Japanese mustard spinach

Responses of Japanese mustard spinach (JM-spinach; Brassica rapa L. var. pervirdis) were investigated at elevated levels of arsenic (As). Plants were grown hydroponically in the greenhouse under 0, 6.7, 33.5 and 67 μM As (equal to 0, 0.5, 2.5 and 5 mg L^?1 As, respectively) for 14 days. Arsenic was used as sodium meta-arsenite (NaAsO₂). Toxicity symptom was solely shown as shoot growth repression at 33.5 and 67 μM As exposures. Dry weight (DW) enhanced by 19.4% in shoot and 38.9% in root in the 6.7 μM As level as compared to control but decreased by 48.1% and 72.1% DW in shoot and 24.1% and 61.1% DW in root in the 33.5 and 67 μM As levels, respectively. This result indicated that As at lower concentration might have slight stimulating effect on JM-spinach growth, but toxicity increased with increasing As. Based on the regression lines between growth and As concentration in the plant tissues, the critical toxicity level (CTL) of As in JM-spinach shoot was 7.85 μg g^?1 DW considering 10% DW reduction. The CTL for the root was almost 2110 μg As g^?1 DW, indicating that shoot of JM-spinach was more sensitive to As-toxicity than that of root. Arsenic concentrations increased in plant parts with increasing As in the medium. Arsenic concentrations were also compared in DW and fresh weight (FW) basis. The JM-spinach concentrated unaccepted level of As in shoots for human consumption in the higher As levels without showing visible toxicity symptom. In spite of decreasing iron (Fe) concentration in shoot in the highest As level, chlorophyll index did not decrease accordingly. Phosphorus (P) concentration also decreased. Phosphorus concentration decreased much more than Fe concentration. Low P might help to mobilize Fe in shoots, resulting in higher chlorophyll index at 67 μM As level. Phosphorus might compete with Fe in shoot tissues of As-stressed JM-spinach.     

Phosphorus availability and rootstock affect copper-induced damage to the root ultra-structure of Citrus

The control of several citrus diseases requires continuous applications of fungicides containing copper (Cu) which favor to the accumulation of this metal in the soil. Therefore, the evaluation of how nutrient availability and rootstock interact with Cu toxicity in the citrus trees is required to maintain sustainability of fruit production in Cu-contaminated soils. Valencia orange trees on Sunki mandarin (SM) or Swingle citrumelo (SC) rootstock were grown in nutrient solutions combining adequate Cu (1.0 μmol L⁻¹), excess Cu (50.0 μmol L⁻¹), deficient phosphorus (P) (0.01 mmol L⁻¹) and sufficient P (0.5 mmol L⁻¹). The excess Cu reduced root and shoot growth, chlorophyll and relative water content in the leaves of the trees compared to those under adequate Cu supply. Furthermore, excess Cu caused severe damage to the root ultra-structure, characterized by the degeneration of the middle lamella and the presence of a thin and sinuous cell wall, as well as, starch accumulation in the plastids, disruption of the mitochondrial membranes and cellular plasmolysis. The damage caused by excess Cu in the cell wall and middle lamella on the root cells of SC was less severe than SM. Sufficient P supply improved the structure of the cell wall and middle lamella of trees subjected to excess Cu in comparison to P-deficient ones. Thus, the occurrence of more preserved cell wall and middle lamella supports the idea that sufficient P availability in the rooting medium and the use of SC rootstock might contribute to increase the ability of young citrus trees to cope with Cu toxicity.     

Effect of probiotic L. plantarum IS-10506 and zinc supplementation on humoral immune response and zinc status of Indonesian pre-school children

A 90-day randomized, double-blind, placebo-controlled, pre-post trial was conducted in four groups of Indonesian children aged 12–24 months: placebo, probiotic, zinc, and a combination of probiotic and zinc (n = 12 per group). Microencapsulated Lactobacillus plantarum IS-10506 of dadih origin was supplemented at a dose of 10¹⁰ CFU/day as a probiotic. Zinc was supplemented as 20 mg zinc sulfate monohydrate (8 mg zinc elemental). Blood and stool samples were collected at baseline and at the end of the study period. Fecal sIgA was assessed by ELISA and serum zinc concentrations by ICP-MS. Fecal sIgA increased significantly in the probiotic group (30.33 ± 3.32 μg/g; p < 0.01) and in the combination probiotic and zinc group (27.55 ± 2.28 μg/g; p < 0.027), as compared with the placebo group (13.58 ± 2.26 μg/g). Changes in serum zinc concentrations in the combination probiotic and zinc group showed the highest elevation at the end of the study period. A combination of probiotic L. plantarum IS-10506 at a dose of 10¹⁰ CFU/day and 8 mg of elemental zinc supplementation showed a potential ability to improve the zinc status of pre-school children. Taken together, supplementation with the probiotic L. plantarum IS-10506 and zinc for 90 days resulted in a significantly increased humoral immune response, as well as improved zinc status, in young children.     

Salt tolerant Methylobacterium mesophilicum showed viable colonization abilities in the plant rhizosphere

The source of infection has always been considered as an important factor in epidemiology and mostly linked to environmental source such as surface water, soil, plants and also animals. The activity of the opportunistic pathogens associated with plant root, their adaptation and survival under hostile environmental condition is poorly understood. In this study the salt tolerance ability of Methylobacterium mesophilicum and its colonization in the root and shoot of plants under severe drought and salt stress conditions were investigated. The colonization of plant by M. mesophilicum was investigated in a gnotobiotic sand system, and their survival in pots with saline soil. Bacterial strain was found to colonize rhizosphere of cucumber, tomato and paprika grown under normal and salt stress condition and reached up to 6.4 × 10⁴ and 2.6 × 10⁴ CFU/g root. The strain was resistant to Gentamicin, Ampicillin, Amoxicillin plus Clavulanic acid, Cefotaxime, neomycin, penicillin and was also tolerant to salinity stress (up to 6% NaCl). These abilities play important roles in enabling persistent colonization of the plant surface by M. mesophilicum strains. In conclusion, this study provides background information on the behaviour of opportunistic pathogen M. mesophilicum on plants and their survival in harsh environmental conditions.     

Effects of zinc supplementation on serum zinc and leptin levels,BMI, and body composition in hemodialysis patients

ProjectThe aim of this study was to determine the effects of zinc supplementation on serum zinc and leptin levels as well as on anthropometric status and some biochemical parameters in hemodialysis (HD) patients.ProcedureIn this randomized, double-blind, and placebo-controlled trial, sixty HD patients were randomly divided into groups to receive a daily supplement of 100 mg elemental Zn (supplemented group) or placebo (control group) for 60 days. Anthropometric measurements were taken using standard calibrated instruments. Serum zinc and leptin levels were determined by atomic absorption and ELISA method respectively before and after intervention.ResultsZinc supplementation resulted in significant increase in the mean serum zinc level in the experimental group while changes observed in the placebo group were not significant. The mean serum leptin in women part of the experimental group was decreased significantly after supplementation. After adjusting for age, BMI, body fat (%), serum zinc and dietary Zn intake, a negative and significant association was observed between serum zinc and leptin levels in all subjects (β = −0.33, P = 0.03) as a result of Zn supplementation.ConclusionsMore studies are needed to clarify the mechanisms by which serum leptin level is influenced as a result of zinc supplementation in HD patients.     

Interactive effects of salinity and water depth on the growth of Melaleuca ericifolia Sm. (Swamp paperbark) seedlings

Melaleuca ericifolia Sm. (Swamp paperbark) is a common tree species in freshwater and brackish wetlands in southern and eastern Australia. The survival of this species in many wetlands is now threatened by increased salinity and inappropriate water regimes. We examined the response of 5-month-old M. ericifolia seedlings to three water depths (exposed, waterlogged and submerged) at three salinities (2, 49 and 60 dS m⁻¹). Increasing water depth at the lowest salinity did not affect survival, but strongly inhibited seedling growth. Total biomass, leaf area and maximum root length were highest in exposed plants, intermediate in waterlogged plants and lowest in submerged plants. Although completely submerged plants survived for 10 weeks at the lowest salinity, they demonstrated negative growth rates and were unable to extend their shoots above the water surface. At the higher salinities, M. ericifolia seedlings were intolerant of waterlogging and submergence: all plants died after 9 weeks at 60 dS m⁻¹. Soil salinities increased over time, and by Week 10, exceeded external water column salinities in both the exposed and waterlogged treatments. In exposed sediment, ∼90% of plants survived for 10 weeks at 60 dS m⁻¹ even though soil salinities reached ∼76 dS m⁻¹. No mortality occurred in the exposed plants at 49 dS m⁻¹, and small but positive relative growth rates were recorded at Week 10. We conclude that at low salinities M. ericifolia seedlings are highly tolerant of sediment waterlogging, but are unlikely to tolerate prolonged submergence. However, at the higher salinities, M. ericifolia seedlings are intolerant of waterlogging and submergence and died rapidly after 5 weeks exposure to this combination of environmental stressors. This research demonstrates that salinity may restrict the range of water regimes tolerated by aquatic plants.     

Design,synthesis and anticancer activity of piperazine hydroxamates and their histone deacetylase (HDAC) inhibitory activity

Six compounds were synthesized with piperazine in linker region and hydroxamate as Zinc Binding Group (ZBG). They were screened against three cancer cell-lines (NCIH460; HCT116; U251). Compounds 5c and 5f with GI₅₀ value of 9.33 ± 1.3 μM and 12.03 ± 4 μM, respectively, were tested for their inhibitory potential on hHDAC8. Compound 5c had IC₅₀ of 33.67 μM. Compounds were also screened for their anticancer activity against HL60 human promyelocytic leukemia cell line due to the presence of pharmacophoric features of RR inhibitors in them. Compound 5c had IC₅₀ of 0.6 μM at 48 h.     

Expression analysis and biochemical characterization of beans plants biofortificated with zinc

The present work was carried out in greenhouse conditions at the Centro de Investigación en Alimentación y Desarrollo AC in Delicias, Chihuahua, México. Four different concentrations (0, 25, 50 and 100 μM L⁻¹) of Zn chelate and sulfate were used to study the antioxidant system of Phaseolus vulgaris L. Three genes related with antioxidant activity [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)] were selected for expression study. Results showed that when Zn chelate at 50 and 100 μM L⁻¹ were applied SOD was repressed and GSH-Px expression was low at 0, 25 and 100 μM L⁻¹ while with sulfate form SOD expression was low and GSH-Px expression was strong in all treatment. CAT was highly expressed in all form and treatments. For a biochemical study the same enzymes were spectrophotometrically measured. SOD activity shows differences in both forms of Zn, chelate form was different at 25, 50 and 100 μM L⁻¹ with less activity at 100 μM L⁻¹ and sulfate treatment shows differences in all concentrations used. GSH-Px activity shows significant differences with sulfate form at 25, 50 μM L⁻¹ where at 50 μM the activity was higher and low at 100 μM L⁻¹, CAT does not exhibit significant differences but with chelate treatment at 50–100 μM L⁻¹ the activity was higher compared to sulfate. Finally, to raise the Zn concentration in bean under biofortification program is a promising strategy in cropping systems in order to increase the ingestion of zinc and antioxidant capacity in the general population and provided the benefits that this element offered in human health.     

Biochemical responses of the aquatic moss Fontinalis antipyretica to Cd,Cu, Pb and Zn determined by chlorophyll fluorescence and protein levels

Biochemical reactions to Cu, Cd, Zn and Pb in the aquatic moss Fontinalis antipyretica were studied in order to characterize the physiological background of the metal response. Chlorophyll fluorescence and intracellular metal localization and stress protein levels were measured. Exposure to 25 or 100 μM Cu over a 7-day period resulted in a decline of chlorophyll fluorescence to about 70% and 52%, respectively. Up to 100 μM Cd caused a decrease in chlorophyll fluorescence to 75%. With all metals used at 25–100 μM concentrations, the intracellular uptake increased. For all metals investigated at 25–100 μM, the intracellular uptake increased. Maximum values were reached at 100 μM Cu, Pb, Zn or Cd exposure. As shown by analytical electron microscopy (EDX, EELS) moss material treated with 50 μM Cu exhibited reduced sulphur levels in the cytoplasm and an increase in phosphate in vacuolar dense particles. EEL-spectra indicated that Cu is chelated in the cytoplasm by SH-groups and coprecipitated with orthophosphate in vacuoles. To monitor the stress response at the protein level, heavy metal induced heat shock protein 70 (hsp70) was measured. An antibody was raised against conserved plant metallothionein p2 motifs derived from Brassica juncea. In all metal-treated samples the antibody bound to proteins of about 8 kDa. However, sequencing failed to reveal significant homologies to known proteins. These experiments provide for the first time results on protein level after heavy metal stress in the aquatic bioindicator moss.