Total GR Research Articles

Oxidative Damages of Two Neonicotinoid Pesticides to Arthrospira platensis (Gomont)

In this study, chlorophyll-a amount, OD 560 and antioxidant parameters (total SOD, APX, GR, MDA, H2O2 and Proline) were determined in order to understand the effects of Thiacloprid and Imidacloprid on Arthrospira platensis Gomont. Both Imidacloprid and Thiacloprid applications showed significant reductions in growth rate and chlorophyll-a content of A. platensis cultures with dose-dependent manner when the days and concentrations were compared each other. SOD activity significantly decreased in the Imidacloprid application while Thiacloprid caused a significant increase only at 75 µg mL-1 concentration. APX activity significantly increased in the Imidacloprid and Thiacloprid applications at 50 µg mL-1 and 35 µg mL-1 concentrations, respectively. Imidacloprid treatment increased GR activity at 20 and 30 µg mL-1 concentrations while GR activity increased at 15, 25 and 35 µg mL-1 Thiacloprid concentrations. The MDA content of A. platensis cultures did not change with Imidacloprid or Thiacloprid applications. The H2O2 content did not change at all different Imidacloprid concentrations. However, the H2O2 content decreased at 15 µg mL-1 and increased at 45 and 75 µg mL-1 Thiacloprid concentrations. Free proline content increased in the Imidacloprid and Thiacloprid applications at 100 µg mL-1 and 75 µg mL-1 concentrations, respectively. These neonicotinoid pesticides cause oxidative stress in A. platensis cells.

Quaternary warming and cooling trends in the Bransfield Basin, Antarctic Peninsula, based on gamma-ray spectrometry

Spectral gamma-ray measurements were carried out on eight cores collected in the Bransfield Strait at points distributed over a cross section connecting the South Shetland Islands (NW) and the Antarctic Peninsula (SE). These cores were acquired during the cruises OPERANTAR XXXIII, XXXIV, and XXXV, aboard the P/V Almirante Maximiano, from the Brazilian Navy, within the scope of the project “Use of Sedimentary and Biogeochemical Records as Indicative of Climate and Environmental Changes in the South Shetland Islands and Antarctic Peninsula”. The energy spectrum was measured in counts per period through a portable spectrometer which displays the total gamma-ray (total GR) counts, in addition to the individual concentrations of K (%), U (ppm), and Th (ppm), internally converted. The results, integrated with core sedimentological descriptions, enabled us to characterize the different geochemical environments and to recognize paleoenvironmental cycles and stratigraphic surfaces, proving to be a powerful tool for high-resolution stratigraphic studies. The Th/U and U/K ratios reveal six well-marked cycles (identified from A to F) interpreted as transitions from warm to cold periods. The increase in Th/U ratio was used as a proxy for higher clastic meltwater sedimentary input during warm periods, while the increase in U/K ratio indicates higher amounts of organic matter, and therefore higher U content, during cold periods, when clastic sedimentary input is smaller. The concomitant decrease in the Th/U ratio with the increase in the U/K ratio suggests a gradual change from a warm to a cold period. Otherwise, the gradual increase in the Th/U ratio and decrease in the U/K ratio indicates the transition from cold to warm periods. In addition, this study observed different behaviors between proximal and distal gamma-ray spectral logs.

Adverse maternal environment and western diet impairs cognitive function and alters hippocampal glucocorticoid receptor promoter methylation in male mice.

Adverse maternal environment (AME) and high‐fat diet in early childhood increase the risk of cognitive impairment and depression later in life. Cognitive impairment associates with hippocampal dysfunction. A key regulator of hippocampal function is the glucocorticoid receptor. Increased hippocampal GR expression associates with cognitive impairment and depression. Transcriptional control of GR relies in part upon the DNA methylation status at multiple alternative initiation sites that are tissue specific, with exon 1.7 being hippocampal specific. Increased exon 1.7 expression associates with upregulated hippocampal GR expression in early life stress animal models. However, the effects of AME combined with postweaning western diet (WD) on offspring behaviors and the expression of GR exon 1 variants in the hippocampus are unknown. We hypothesized that AME and postweaning WD would impair cognitive function and cause depression‐like behavior in offspring in conjunction with dysregulated hippocampal expression of total GR and exon 1.7 variant in mice. We found that AME‐WD impaired learning and memory in male adult offspring concurrently with increased hippocampal expression of total GR and GR 1.7. We also found that increased GR 1.7 expression was associated with decreased DNA methylation at the GR 1.7 promoter. We speculate that decreased DNA methylation at the GR 1.7 promoter plays a role in AME‐WD induced increase of GR in the hippocampus. This increased GR expression may subsequently contribute to hippocampus dysfunction and lead to the cognitive impairment seen in this model.

Evaluation of Azadirachtin onArthrospira plantensisGomont growth parameters and antioxidant enzymes

Azadirachtin (Aza) used as insecticide due to inhibiting growth of insects and preventing them from feeding on plants. To understand the effects of contamination of this insecticide on phototrophs, and to determine the responses of these organisms against these insecticides are extremely important in understanding how the ecosystem is affected. In this study, chlorophyll-aamount, OD 560 and antioxidant parameters (total SOD, APX, GR, Proline, MDA and H2O2) were determined in order to understand the effect of Aza onArthrospira platensisGomont. Aza was applied between 0–20 μg mL−1concentrations for 7 days in the study. Enzyme analysis was conducted at the end of the 7th day. There was a statistically significant decrease in the absorbance of OD560 and the chlorophyll-acontent inA. platensiscultures exposed to the Aza (0–20 μg mL−1) during 7 days due to the increase in pesticide levels. SOD activity decreased at 8, 16 and 20 μg mL−1concentrations; GR enzyme activity showed a significant decrease compared to the control at a concentration of 20 μg mL−1. APX activity did not change significantly compared to control. The MDA content increased significantly at 16 and 20 μg mL−1concentrations. The H2O2content significantly increased at 12, 16 and 20 μg mL−1concentrations (p< 0.05) while the free proline content decreased at 4 μg mL−1concentration (p< 0.05). As a result, regarding the Aza concentrations used in this study may be a step to prevent pesticide pollution in the environment.

Archival gamma ray logs standardization by nondestructive core measurements of the low-radioactivity rocks

The present study analyzes spectral gamma ray data of low-radioactivity rock cores from Rotliegend Basin. The main goal of this research was standardization of archival gamma ray logs measured in counts per minute to American Petroleum Institute units. Selected core intervals, log data, and additional crushed samples covered three different boreholes: J-1, L-7, and K-2 from Zielona Góra Basin, localized in western Poland, where J-1 was a reference borehole. Core measurements were performed on the sandstone and conglomerate formations by Gamma Logger GT spectrometer, which uses two scintillation detectors containing bismuth germanate crystals. In the cores, real concentrations of potassium, uranium, and thorium were acquired what enabled to calculate total content of radioactive elements and total uninfluenced by uranium. Delivered new total GR_GLGT curve from cores allowed accurate standardization of archival GR curves from L-7 and K-2 boreholes. Presented results showed a very good correlation between logs, core data, and laboratory analyses. These data allow precise shale volume reinterpretation.

Decreased Lipid Profile and Oxidative Stress in Healthy Subjects Who Underwent Whole-Body Cryotherapy in Closed Cryochamber with Subsequent Kinesiotherapy.

Objective The aim of the study was to estimate the impact of whole-body cryotherapy (WBC) and subsequent kinesiotherapy on oxidative stress and lipid profile when performed in a closed cryochamber on healthy subjects. Material and Methods The effect of ten WBC procedures lasting 3 minutes a day followed by a 60-minute session kinesiotherapy on oxidative stress and lipid profile in healthy subjects (WBC group, n = 16) was investigated. The WBC group was compared to the kinesiotherapy only (KT; n = 16) group. The routine parameters of oxidative stress (antioxidant enzymatic and nonenzymatic antioxidant status, lipid peroxidation products, total oxidative status (TOS), and oxidative stress index (OSI)) and lipid profile were estimated one day before the beginning and one day after the completion of the research program. Results After treatment, in the WBC group, a significant decrease of oxidative stress markers (TOS and OSI) and a significant increase of total antioxidant capacity were observed. The activity of plasma SOD-Mn and erythrocyte total SOD increased significantly in the WBC group. In the KT group, the erythrocyte activity of total SOD, CAT, and GR decreased significantly after the treatment. The levels of T-Chol and LDL-Chol decreased significantly after treatment in both groups, but the observed decrease of these lipid parameters in the WBC group was higher in comparison to the KT group. The level of TG decreased significantly after treatment in the WBC group only. Conclusion WBC performed in a closed cryochamber followed by kinesiotherapy improves lipid profile and decreases oxidative stress in healthy subjects.

Variation of the epidermal expression of glucocorticoid receptor-beta as potential predictive marker of bullous pemphigoid outcome.

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease in Western countries. Although topical and/or systemic glucocorticoids treatment efficacy is widely recognized, up to 30% of patients with BP may undergo a relapse during the first year of treatment. We investigated the protein expression of the total glucocorticoid receptor and GRβ isoform in the skin biopsy specimens from patients with BP and wondered whether such investigation at baseline provided a tool to predict disease outcome. Total GR and GRβ protein expressions were detected by immunohistochemistry at baseline on 12 patients who later relapse and 11 patients who remained on remission in comparison with 14 control patients. The expression of GRβ in the epidermis of patients with BP who later relapse was significantly higher than that in the epidermis of patients with BP controlled upon corticosteroid treatment, which was also higher than control patients. Thus, our results suggest that increased protein expression of GRβ in skin epithelial cells is predictive of reduced steroid treatment efficacy, and therefore of increased risk of disease relapse in patients with BP.

In Vitro Amelioration by Curcumin on Genotoxicity in Workers with Elevated Blood Cadmium Level

Curcumin is a dietary element, easily available and also well-known herb, for its therapeutic uses. On the other hand, cadmium is considered as an omnipresent, hazardous, heavy metal as well as known carcinogen, clastogen and mutagen. It is known to produce severe toxic effects during occupational exposure in industries related to nickel-cadmium batteries, pigments, chemical stabilizers, metal coatings and alloys in humans. So, the objective of this study was to evaluate the ameliorative effects of curcumin as an antioxidant agent against cadmium induced genotoxicity in Peripheral Blood Lymphocyte Cultures (PBLC) of occupationally cadmium exposed individuals. The blood cadmium level was determined and it was significantly higher in exposed individuals as compared to controls. Blood samples from 40 workers exposed to cadmium, and 40 unexposed controls were used to analyse biochemical parameters like Total protein, GSH, GPx, GR, GST, LPO, CAT and SOD along with genotoxic parameters like SCEs, CCPI, AGT and PDT. The study revealed cadmium induced the free radicals formation which caused alteration in antioxidant defense system and may lead to genotoxicity. While curcumin ameliorates this toxicity by balancing the antioxidant defense system, decrease the lipid peroxidation and ultimately protect cells against cadmium genotoxicity. Hence, it can be concluded that curcumin which is herbal antidote can be helpful to protect cadmium toxicity in occupationally exposed workers.

Astaxanthin; a Promising Protector Against Gentamicin-Induced Nephrotoxicity in Rats.

Gentamicin is an aminoglycoside antibiotic widely used against infections caused by Gram-negative microorganisms. Nephrotoxicity is the main limitation to its therapeutic use. The objective of this study was to evaluate the potential protective effect of astaxanthin on the renal damage generated by gentamicin in rats, in an attempt to understand its mechanism of action, which may pave the way for possible therapeutic applications. The daily oral administration of the astaxanthin at a concentration of 50 mg/kg for 15 days to gentamicin (80 mg/kg.b.w) treated rats showed a significant decrease (p<0.05) in plasma creatinine, urea, TNF-α as well as plasma and renal MDA and HP. The treatment also resulted in a significant increase in hemoglobin, plasma sodium, potassium and TAS as well as renal total protein, GSH, Pr-SHs, G6PD, SOD, GPx, CAT and GR levels. The histological examinations of renal tissues in this study revealed damage and glomerular infiltration in gentamicin treated rats. The presented data suggest that astaxanthin has a significant prophylactic action against gentamicin-induced nephrotoxicity in rats. The effect was more pronounced in case of astaxanthin pre-treatment compared with administration of astaxanthin post-treatment. Taken together, astaxanthin has a potential as a protective and therapeutic agent for nephrotoxicity and deserves clinical trial in the near future as an adjuvant therapy in patients treated with gentamicin.

Role of the 5′-untranslated regions in post-transcriptional regulation of the human glucocorticoid receptor

GR transcripts display a remarkable heterogeneity in their 5′ untranslated regions (5′UTRs). These variable 5′UTRs are encoded by a series of alternative 1st exons, and together with their associated promoters they maintain tissue-specific GR expression levels. In this study we over-expressed GR transcripts containing individual 1st exons, and assessed their effect on RNA stability, 3′-splicing, translation initiation and protein isoform production. We showed that these alternative 5′UTRs influence the predicted mRNA structure and free energy, and were associated with differential levels of functional spliced mRNA. However, the 5′UTR had little influence on the relative levels of the two principal 3′ splice transcripts, GR-α and -β. The overall mRNA length, the free energy of the transcript and the translational efficiency directly influenced total GR levels. However, individual N-terminal protein isoform levels appeared to depend upon elements within the 5′UTR. Membrane-GR specific labelling suggested that the mGR originates from transcripts containing exon 1D and possibly 1H, although the specific trafficking sequences or structures within these transcripts remain unidentified. The role of the alternative first exons and their associated 5′UTRs has now been expanded to translational control, influencing total GR levels, individual constituent isoform levels, as well as trafficking to the cell surface.

A revision of the Rutilus complex from Mediterranean Europe with description of a new genus, Sarmarutilus, and a new species, Rutilus stoumboudae (Teleostei: Cyprinidae).

By combining morphology, ecology, biology, and biogeography with the available molecular (sequence variation of the entire mitochondrial cytochrome b gene; cyt-b) and karyology data, the taxonomy of several species of the Rutilus complex inhabiting southern Europe is revised. Rutilus stoumboudae, new species, is described from Lake Volvi, Greece. It differs from Rutilus rutilus in possessing more total GR and less branched rays in both dorsal and anal fins and in its placement in the cyt-b based phylogeny of the genus. The resurrected genus Leucos Heckel, 1843 (type species Leucos aula, Bonaparte, 1841), which according to molecular data diverged from Rutilus more than 5 million years ago, during the Messinian salinity crisis, includes five species of small size, without spinous tubercles on scales and head in reproductive males, pharyngeal teeth formula 5-5, and all show a preference for still waters. Leucos aula is the Italian species endemic in the Padany-Venetian district: L. basak is widespread in Croatia, Albania, Montenegro and former Yugoslav Republic of Macedonia (FYROM); L. albus, recently described from Lake Skadar, Montenegro, is also found in rivers Moraca and Zeta (Montenegro). L. albus differs from L. basak, its closest relative, in having more scales on the LL and less anal-fin rays; L. panosi is endemic to the western-Greece district, and L. ylikiensis is endemic to lakes Yliki and Paralimni in eastern Greece (introduced in Lake Volvi). Among the nominal species examined, Rutilus karamani, R. ohridanus, R. prespensis and R. prespensis vukovici are all junior synonyms of Leucos basak. Rutilus vegariticus is definitively regarded as junior synonym for R. rutilus. Sarmarutilus n.gen. is a monotypic genus, with Sarmarutilus rubilio as the type species. According to phylogenetic data, Sarmarutilus rubilio is basal to a cluster of species that includes Leucos basak, L. albus, L. aula, L. panosi and L. ylikiensis. Sarmarutilus possibly evolved in pre-Messinian time, in the Lago Mare, entered the Mediterranean area during the Messinian Lago Mare phase of the Mediterranean Sea and survived only in the Tuscany- Latium district. This genus differs from Leucos in having large pearl organs on the central part of head and body scales in mature males and for the habitat preference, being a riverine-adapted species. It differs from Rutilus in pharyngeal teeth formula (5-5 in Sarmarutilus and 6-5 in Rutilus), size (small in Sarmarutilus and large in Rutilus) and for the preferential habitat (riverine vs. still water). Finally, lectotypes for Leucos basak, Leucos aula, and Sarmarutilus rubilio are designated.

Depositional Environment of Shallow-Marine Sandstones from Outcrop Gamma-Ray Logs, Belait Formation, Meragang Beach, Brunei Darussalam

The outcrop of shallow marine sandstone, Belait formation at Meragang Beach, Brunei Darussalam have long been regarded as tide-, wave- and storm-dominated environment that reveals the reservoir heterogeneities and variation in sand body geometry. Intensive outcrop study methods were available from previously conducted work on Belait Formation. But for this study the priority was to acquire gamma-ray profile at 5-10 cm scale by using Digital Total GR Count Detector and re-logged of Sedimentological log (in cm) of 311.8 m thick outcrop to describe the depositional environment and sedimentary facies architecture. The sediments deposited in a tide-dominated environment mostly interpreted in all cycles which were characterized by sub-depositional environment which includes; tidal channel, muddy tidal flat and mixed tidal flat sub-environment with sedimentary facies of planner cross-bedding, trough cross-bedding, herringbone cross-stratification, wave ripples and thin parallel lamination with coal fragmented bed and carbonaceous material. The gamma-ray profile for tide dominated environment shows different shapes; block left-boxcar, bell shape, funnel shape and irregular trend. In wave- and storm-dominated are wave ripples, thin parallel lamination with mud drapes, large planner cross-bedding, trough cross-bedding, highly bioturbated (skalithos) sandstone and hummocky cross-stratification. Whereas, the gamma-ray profile shows different shapes; left-boxcar, right-boxcar, funnel shape and irregular trend and in storm-dominated it show only left-boxcar with no sharp edges on top and bottom. This approach combines excellent data quality to interpretate different depositional environment and its impact on sandstone quality which implies that the outcrop gamma-ray log can use to characterize the rock deposited in different depositional environment in different facies. It also reveals that the changes in gamma-ray profile with in the sandstone depend upon the environment in which the sandbody deposited that reveal in reservoir heterogeneities in subsurface well correlation.

Contribution of MEK1/ERK1/2/iNOS Pathway to Oxidative Stress and Decreased Caspase-3 Activity in Endotoxemic Rats

Oxidative stress and apoptosis are the states that can contribute to the pathogenesis of sepsis. In this study we aimed to investigate whether mitogen-activated protein kinase kinase 1 (MEK1)/extracellular signal-regulated kinase 1/2 (ERK1/2)/inducible nitric oxide synthase (iNOS) pathway plays a role in oxidative stress and apoptosis in endotoxemic rats. Systemic total antioxidant, SOD, GPx, and GR activities as markers of oxidative stress, and tissue caspase-3 enzyme activity as a marker of apoptosis were measured in sera and thoracic aortae of male Wistar rats sacrificed 4 h after being treated with saline (vehicle) or lipopolysaccharide (LPS) (10 mg/kg, i.p.). A decrease in total antioxidant activity and caspase-3, SOD, GPx, and GR enzyme activities was occured by LPS. These changes caused by LPS were prevented when a selective iNOS inhibitor, 1,3-PBIT (10 mg/kg, i.p.) or a selective inhibitor of ERK1/2 phosphorylation by MEK1, U0126 (5 mg/kg, i.p.) were given 1 h after administration of LPS. Our results suggest that decreased activity of MEK1/ERK1/2/iNOS pathway prevents oxidative stress by increasing systemic antioxidant enzyme activities and restores decreased caspase-3 activity in thoracic aorta in endotoxemic rat.

Breed-Dependent Transcriptional Regulation of 5′-Untranslated GR (NR3C1) Exon 1 mRNA Variants in the Liver of Newborn Piglets

Glucocorticoids are vital for life and regulate an array of physiological functions by binding to the ubiquitously expressed glucocorticoid receptor (GR, also known as NR3C1). Previous studies demonstrate striking breed differences in plasma cortisol levels in pigs. However, investigation into the breed-dependent GR transcriptional regulation is hampered by lacking porcine GR promoter information. In this study, we sequenced 5.3 kb upstream of the translation start codon of the porcine GR gene, and identified seven alternative 5′-untranslated exons 1–4, 1–5, 1–6, 1–7, 1–8, 1–9,10 and 1–11. Among all these mRNA variants, exons 1–4 and 1–5, as well as the total GR were expressed significantly (P<0.05) higher in the liver of newborn piglets of Large White (LW) compared with Erhualian, a Chinese indigenous breed. Overall level of CpG methylation in the region flanking exons 1–4 and 1–5 did not show breed difference. However, nuclear content of Sp1, p-CREB and GR in the liver was significantly (P<0.05) higher in LW piglets, associated with enhanced binding of p-CREB, and higher level of histone H3 acetylation in 1–4 and 1–5 promoters. In contrast, GR binding to promoters of exons 1–4 and 1–5 was significantly diminished in LW piglets, implicating the presence of negative GREs. These results indicate that the difference in the hepatic expression of GR transcript variants between two breeds of pigs is determined, at least partly, by the disparity in the binding of transcription factors and the enrichment of histone H3 acetylation to the promoters.

Erratum: Corrigendum: Epigenetic modulation of the renal β-adrenergic–WNK4 pathway in salt-sensitive hypertension

Nat. Med. 17, 573–580 (2011); published online 17 April 2011; corrected after print 4 August 2011 In the version of this article initially published, the authors made several inadvertent errors during manuscript preparation. In Figure 3f the trace for WT mice was incorrect, and in Figure 4a the bands shown for 'Total GR' were incorrect.

Intrauterine growth retardation affects expression and epigenetic characteristics of the rat hippocampal glucocorticoid receptor gene

Studies in humans and rats suggest that intrauterine growth retardation (IUGR) permanently resets the hypothalamic-pituitary-adrenal (HPA) axis. HPA axis reprogramming may involve persistently altered expression of the hippocampal glucocorticoid receptor (hpGR), an important regulator of HPA axis reactivity. Persistent alteration of gene expression, long after the inciting event, is thought to be mediated by epigenetic mechanisms that affect mRNA and mRNA variant expression. GR mRNA variants in both humans and rats include eleven 5'-end variants and GRalpha, the predominant 3'-end variant. The 3'-end variants associated with glucocorticoid resistance in humans (GRbeta, GRgamma, GRA, and GRP) have not been reported in rats. We hypothesized that in the rat hippocampus IUGR would decrease total GR mRNA, increase GRbeta, GRgamma, GRA, and GRP, and affect epigenetics of the GR gene at birth (D0) and at 21 days of life (D21). IUGR increased hpGR and exon 1.7 hpGR mRNA in males at D0 and D21, associated with increased trimethyl H3/K4 at exon 1.7 at both time points. IUGR also increased hpGRgamma in males at D0 and D21, associated with increased acetyl H3/K9 at exon 3 at both time points. hpGRA increased in female IUGR rats at D0 and D21. In addition, our data support the existence of hpGRbeta and hpGRP in the rat. IUGR has sex-specific, persistent effects on GR expression and its histone code. We speculate that postnatal changes in hippocampal GR variant and total mRNA expression may underlie IUGR-associated HPA axis reprogramming.

Tissue mRNA expression of the glucocorticoid receptor and its splice variants in fatal critical illness

Critical illness results in activation of the hypothalamic-pituitary-adrenal (HPA) axis, which might be accompanied by a peripheral adaptation in glucocorticoid sensitivity. Tissue sensitivity is determined by the active glucocorticoid receptor GRalpha, of which two splice variants involving the hormone-binding domain exist, GRbeta and GR-P. To study tissue mRNA expression of the GR and its splice variants in fatal critical illness. We assessed mRNA expression of the GRalpha, GRbeta and GR-P variants in liver (n = 58) and muscle (n = 65) of patients who had died after intensive care, and had been randomized for insulin treatment. We analysed whether GR mRNA expression was associated with insulin treatment, cortisol levels and glucocorticoid treatment. GRalpha and GR-P mRNA constituted 87 +/- 8% and 13 +/- 2%, respectively, of total GR mRNA in liver. GRbeta mRNA could only be amplified in five liver samples. All variants were present in most muscle samples (alpha = 96 +/- 11%, P = 3.9 +/- 0.4%, beta = 0.010 +/- 0.002%). GR expression was not associated with insulin therapy. A strong positive relationship was observed between the different GR variants in both liver and muscle (P < 0.001 for all). Serum cortisol levels were negatively associated with liver GRalpha and muscle GR-P expression (P < 0.05). mRNA expression of both liver GRalpha and GR-P, but not muscle GR, was substantially lower in patients who had received exogenous glucocorticoids (P < 0.01). We demonstrate the presence of GRalpha and GR-P mRNA in liver and of GRalpha, GRbeta and GR-P mRNA in muscle, with no evidence for altered splicing in critical illness. In contrast to muscle GR, liver GR expression was substantially lower in patients receiving exogenous glucocorticoids.

A crop tolerating oxidative stress induced by excess lead: maize

Two 14-day-old seedlings of maize (Zea mays L.) cultivars (3223 and Vero) were exposed to different concentrations of lead [0, 2, 5 and 8 mM Pb(NO3)2·4H2O] for 8 days. Exposure of maize cultivars to excess Pb resulted in a significant root growth inhibition though shoot growth and absolute water content remained less affected. The results of chlorophyll a fluorescence indicated that the highly toxic Pb level affected photochemical efficiency in 3223, while no significant effect was observed in the Vero. At the highly toxic Pb concentration, higher membrane leakage was observed in 3223 leaves than that of Vero. This result was related to the accumulation of Pb. On the other hand, the results suggested that there were similar responses in total soluble POD and GR activities with increasing Pb concentrations between both cultivars. But APX activity significantly decreased at highly toxic Pb level in the Vero while a significant increase observed in the 3223. However, SOD activity in 3223 significantly decreased at the highly toxic Pb concentration compared with that at 2 mM Pb concentration. The results of the present study indicated that, Vero withstands excess Pb with its higher Pb accumulation capacity in roots and better upregulated protective mechanisms compared to 3223. Therefore, Vero is more tolerant to Pb toxicity compared to 3223 which was found to be a less tolerant cultivar.

PSII Photochemistry and Antioxidant Responses of a Chickpea Variety Exposed to Drought

The effect of drought on the chickpea variety ILC 3279 was investigated at the vegetative stage. After 20 days from sowing, the plants subjected to drought stress for 3, 5 and 7 days imposed by withholding water were permitted to recover by rewatering for 2 days after 3, 5 and 7 days of drought. Shoot elongation, leaf production, fresh and dry biomass reduced while MDA and proline accumulation increased with extended duration of stress. The plants stressed for 3 days exhibited a rapid drop in their relative and absolute water contents. The quantum efficiency of PSII open centres in the dark-adapted and light-saturated state, excitation energy trapping of PSII and electron transport rate decreased significantly from the 5th day to the end of the drought treatments. Plants drought-stressed for 7 days brought about a marked increase in non-photochemical energy dissipation and a marked decline in photochemical quenching. After rewatering all chlorophyll a fluorescence characteristics except for F(M) completely recovered and reached the control values. Under 5 and 7 days of drought, the anthocyanin content increased gradually while the total chlorophyll content of leaves declined compared to the controls. The total carotenoid content remained unchanged during the experiments. The antioxidant enzyme response to drought treatments was quite variable. The total SOD activity upregulated with increasing duration of stress. On the other hand, the total APX activity was significantly higher only on the 7th day while the total POD activity increased from the 5th day. Differences in the total GR activity of treated groups were not statistically significant compared to their controls throughout the treatments. The present results indicate that the chickpea variety ILC 3279 withstands severe drought with its upregulated protective mechanisms at the vegetative stage.

Neuroprotection by Spirulina platensis protean extract and phycocyanin against iron-induced toxicity in SH-SY5Y neuroblastoma cells

We investigated the effect of Spirulina platensis protean extract and the biliprotein phycocyanin isolated from this microalga, on the activities of the antioxidant enzymes SOD, CAT, GPx, and GR, lipid peroxidation inhibitory activity and glutathione levels after the iron induced oxidative stress in SH-SY5Y neuroblastoma cells. Iron is one of the most important agents that produce oxidative stress and decline of neuronal functions. S. platensis protean extract and phycocyanin exert the antioxidant activity by protecting the activity of the cellular antioxidant enzymes total GPx, GPx-Se and GR and by increasing reduced glutathione in cells against oxidative stress induced by iron. These results suggested that S. platensis protean extract is a powerful antioxidant through a mechanism related to antioxidant activity, capable of interfering with radical-mediated cell death. S. platensis may be useful in diseases known to be aggravated by reactive oxygen species and in the development of novel treatments for neurodegenerative disorders as long as iron has been implicated in the neuropathology of several neurodegenerative disorders such as Alzheimer's or Parkinson diseases.