Nelumbo nucifera leaves extract ameliorated scopolamine-induced cognition impairment via enhanced adult hippocampus neurogenesis.

In this presentation, we explored the molecular mechanisms of N. nucifera leaf water extracts (NLWEs) and polyphenol extract (NLPE) on scopolamine-induced cell apoptosis and cognition defects. The administration of NLWE and NLPE did not alter the body weight and serum biomarker rs and significantly ameliorated scopolamine-induced cognition impairment according to Y-maze test analysis. In mice, treatment with scopolamine disrupted normal histoarchitecture in the hippocampus, whereas the administration of NLWE and NLPE reversed the phenomenon. Western blot analysis revealed that scopolamine mitigated the expression of doublecortin (DCX), nestin, and NeuN, and cotreatment with NLWE or NLPE significantly recovered the expression of these proteins. NLWE and NLPE upregulated DCX and NeuN expression in the hippocampus region, as evidenced by immunohistochemical staining analysis of scopolamine-treated mice. NLWE and NLPE obviously elevated brain-derived neurotrophic factor (BDNF) and enhanced its downstream proteins activity. NLWE and NLPE attenuated scopolamine-induced apoptosis by reducing Bax and increased Bcl-2 expression. In addition, scopolamine also triggered apoptosis in human neuroblastoma SH-SY5Y cells whereas co-treatment with NLWE or quercetin-3-glucuronide (Q3G) reversed the phenomenon. NLWE or Q3G enhanced Bcl-2 and reduced Bax expression in the presence of scopolamine in SH-SY5Y cells. NLWE or Q3G recovered the inhibitory effects of scopolamine on neurogenesis and BDNF signals in SH-SY5Y cells. Overall, our results revealed that N. nucifera leaf extracts and Q3G promoted adult hippocampus neurogenesis and prevented apoptosis to mitigate scopolamine-induced cognition dysfunction through the regulation of BDNF signaling pathway.

Metabolite profiling and screening of callus browning-related genes in lotus (Nelumbo nucifera).

Callus browning is a major drawback to lotus callus proliferation and regeneration. However, the underlying mechanism of its formation remains largely unknown. Herein, we aimed to explore the metabolic and molecular basis of lotus callus browning by combining histological staining, high-throughput metabolomics, and transcriptomic assays for lotus callus at three browning stages. Histological stained brown callus cross sections displayed severe cell death symptoms, accompanied by an obvious accumulation of polyphenols and lignified materials. Widely targeted metabolomics revealed extensively decreased accumulation of most detected flavonoids and benzylisoquinoline alkaloids (BIAs), as well as a few phenolic acids, amino acids and their derivatives in callus with browning symptoms. Conversely, the contents of most detected tannins were significantly increased. Subsequent comparative transcriptomics identified a set of differentially expressed genes (DEGs) associated with the biosynthesis and regulation of flavonoids and BIAs in lotus. Notably, callus browning was coupled with significantly up-regulated expression of two polyphenol oxidase (PPO) and 17 peroxidase (POD) encoding genes, while the expression of ethylene associated genes remained at marginal levels. These results suggest that lotus callus browning is primarily controlled at the level of metabolism, wherein the oxidation of flavonoids and BIAs is crucially decisive.

Overexpression of geranyl diphosphate synthase 1 (NnGGPPS1) from Nelumbo nucifera enhances carotenoid and chlorophyll content and biomass.

As the traditional herb with pharmacological compounds in China, the key genes related with terpenoid biosynthesis are still unveiled in Nelumbo nucifera. Geranylgeranyl pyrophosphate synthase (GGPPS) is one of the key enzymes in terpenoids biosynthesis, synthesizing the common precursor of GGPP for downstream enzymes for generating various terpenoids. In this study, four NnGGPPS genes were isolated from N. nucifera. Sequence and phylogenetic analyses indicate that NnGGPPS1 and NnGGPPS2 belong to large subunit (LSU). Whereas NnGGPPS3 and NnGGPPS4 are classified as small subunit (SSU) of SSU Ⅱ and SSU I, respectively. Among four NnGGPPSs, only NnGGPPS1 and NnGGPPS2 can produce GGPP in bacterial pigment complementation assay. Combination analysis of subcellular localization and gene co-expression analysis (GCN) illustrates that NnGGPPS1 is the main transcript related with methylerythritol phosphate (MEP) pathway, abscisic acid (ABA) biosynthesis, carotenoid and chlorophyll biosynthesis and degradation. Overexpression of NnGGPPS1 improves the growth of transgenic tobacco, and increases carotenoids and chlorophyll contents. Moreover, NnGGPPS1 transgenic tobacco exhibits improved photosynthesis efficiency and ROS scavenging ability. The up-regulated expression of the key genes in MEP pathway, carotenoid biosynthesis and chlorophyll biosynthesis, result in the increase of metabolic flux in NnGGPPS1 transgenic lines. Furthermore, the elevated MEP-derived primary metabolites of carotenoid and chlorophyll was attributed to enhancement of plant biomass of NnGGPPS1 transgenic lines. Therefore, NnGGPPS1 plays a vital role in biosynthesis of carotenoid and chlorophyll.

Substrate specificity of polyphenol oxidase and its selectivity towards polyphenols: Unlocking the browning mechanism of fresh lotus root (Nelumbo nucifera Gaertn.).

Polyphenol oxidase (PPO) causes the browning of lotus roots (LR), negatively affecting their nutrition and shelf-life. This study aimed to explore the specific selectivity of PPO toward polyphenol substrates, thus unlocking the browning mechanism of fresh LR. Results showed that two highly homologous PPOs were identified in LR and exhibited the highest catalytic activity at 35 ℃ and pH 6.5. Furthermore, the substrate specificity study revealed (-)-epigallocatechin had the lowest Km among the polyphenols identified in LR, while (+)-catechin showed the highest Vmax. The molecular docking further clarified that (-)-epigallocatechin exhibited lower docking energy and formed more hydrogen bonds and Pi-Alkyl interactions with LR PPO than (+)-catechin, while (+)-catechin entered the active cavity of PPO more quickly due to its smaller structure, both of which enhance their affinity to PPO. Thus, (+)-catechin and (-)-epigallocatechin are the most specific substrates responsible for the browning mechanism of fresh LR.

Pathway elucidation and microbial synthesis of proaporphine and bis-benzylisoquinoline alkaloids from sacred lotus (Nelumbo nucifera).

Sacred lotus (Nelumbo nucifera) has been utilized as a food, medicine, and spiritual symbol for nearly 3000 years. The medicinal properties of lotus are largely attributed to its unique profile of benzylisoquinoline alkaloids (BIAs), which includes potential anti-cancer, anti-malarial and anti-arrhythmic compounds. BIA biosynthesis in sacred lotus differs markedly from that of opium poppy and other members of the Ranunculales, most notably in an abundance of BIAs possessing the (R)-stereochemical configuration and the absence of reticuline, a major branchpoint intermediate in most BIA producers. Owing to these unique metabolic features and the pharmacological potential of lotus, we set out to elucidate the BIA biosynthesis network in N. nucifera. Here we show that lotus CYP80G (NnCYP80G) and a superior ortholog from Peruvian nutmeg (Laurelia sempervirens; LsCYP80G) stereospecifically convert (R)-N-methylcoclaurine to the proaporphine alkaloid glaziovine, which is subsequently methylated to pronuciferine, the presumed precursor to nuciferine. While sacred lotus employs a dedicated (R)-route to aporphine alkaloids from (R)-norcoclaurine, we implemented an artificial stereochemical inversion approach to flip the stereochemistry of the core BIA pathway. Exploiting the unique substrate specificity of dehydroreticuline synthase from common poppy (Papaver rhoeas) and pairing it with dehydroreticuline reductase enabled de novo synthesis of (R)-N-methylcoclaurine from (S)-norcoclaurine and its subsequent conversion to pronuciferine. We leveraged our stereochemical inversion approach to also elucidate the role of NnCYP80A in sacred lotus metabolism, which we show catalyzes the stereospecific formation of the bis-BIA nelumboferine. Screening our collection of 66 plant O-methyltransferases enabled conversion of nelumboferine to liensinine, a potential anti-cancer bis-BIA from sacred lotus. Our work highlights the unique benzylisoquinoline metabolism of N. nucifera and enables the targeted overproduction of potential lotus pharmaceuticals using engineered microbial systems.

Total alkaloids from the seed embryo of Nelumbo nucifera Gaertn. improve cognitive impairment in APP/PS1 mice and protect Aß-damaged PC12 cells.

The seed embryo of Nelumbo nucifera Gaertn. is a famous traditional Chinese medicine and food which is considered conducive to the prevention of Alzheimer's disease (AD). In this study, the effect and mechanism of TASENN (total alkaloids from the seed embryo of Nelumbo nucifera Gaertn.) on AD mice and amyloid-ß (Aß) injured PC12 cells were evaluated. HPLC-UV analysis showed that the extracted TASENN (purity = 95.6%) mainly contains Liensinine, Isoliensinine, and Neferine (purity was 23.01, 28.02, and 44.57%, respectively). In vivo, oral treatment with TASENN (50 mg/kg/day for 28 days) improved the learning and memory functions of APP/PS1 transgenic mice, ameliorated the histopathological changes of cortical and hippocampal neurons, and inhibited neuronal apoptosis. We found that TASENN reduced the phosphorylation of Tau and the formation of neurofibrillary tangles (NFTs) in APP/PS1 mouse brain. Moreover, TASENN down-regulated the expression of APP and BACE1, ameliorated Aß deposition, and inhibited microglial proliferation and aggregation. The elevated protein expression of CaM and p-CaMKII in APP/PS1 mouse brain was also reduced by TASENN. In vitro, TASENN inhibited the apoptosis of PC12 cells injured by Aß25-35 and increased the cell viability. Aß25-35-induced increase of cytosolic free Ca2+ level and high expression of CaM, p-CaMKII, and p-Tau were decreased by TASENN. Our findings indicate that TASENN has a potential therapeutic effect on AD mice and a protective effect on PC12 cells. The anti-AD activity of TASENN may be closely related to its negative regulation of the CaM pathway.

Sleep-promoting activity of lotus (Nelumbo nucifera) rhizome water extract via GABAA receptors.

CONTEXT: The sleep-promoting activity of Nelumbo nucifera Gaertn. (Nymphaeaceae) alkaloids in leaves or seeds are well known. However, the sleep-promoting activity of the lotus rhizome (LE), which is used mainly as food, has not yet been evaluated. OBJECTIVE: We investigated the sleep-promoting activity of LE water extract. MATERIALS AND METHODS: Institute of Cancer Research (ICR) mice (n = 8) were subject to a pentobarbital-induced sleep test to assess changes in sleep latency and duration following the administration of LE (80-150 mg/kg). In addition, electroencephalography analysis was performed to determine the sleep quality after LE treatment as well as the sleep recovery effect of LE using a caffeine-induced insomnia SD rat model. Real-time PCR and western blot analysis were performed to investigate the expression of neurotransmitter receptors, and the GABAA receptor antagonists were used for receptor binding analysis. RESULTS: An oral administration of 150 mg/kg LE significantly increased sleep duration by 24% compared to the control. Furthermore, LE increased nonrapid eye movement (NREM) sleep by increasing theta and delta powers. In the insomnia model, LE increased sleep time by increasing NREM sleep. Moreover, treatment with picrotoxin and flumazenil decreased the sleep time by 33% and 23%, respectively, indicating an involvement of the GABAA receptor in the sleep-enhancing activity of LE. The expression of GABAA receptors and the concentration of GABA in the brain were increased by LE. DISCUSSION AND CONCLUSIONS: The results suggest that the sleep-promoting activity of LE was via the GABAA receptor. Collectively, these data show that LE may promote sleep.

Hepatoprotective Activity of Nelumbo nucifera Gaertn. Seedpod Extract Attenuated Acetaminophen-Induced Hepatotoxicity.

The aim is to investigate the effect of lotus (Nelumbo nucifera Gaertn.) seedpod extract (LSE) on acetaminophen (APAP)-induced hepatotoxicity. LSE is rich in polyphenols and has potent antioxidant capacity. APAP is a commonly used analgesic, while APAP overdose is the main reason for drug toxicity in the liver. Until now, there has been no in vitro test of LSE in drug-induced hepatotoxicity responses. LSEs were used to evaluate the effect on APAP-induced cytotoxicity, ROS level, apoptotic rate, and molecule mechanisms. The co-treatment of APAP and LSEs elevated the survival rate and decreased intracellular ROS levels on HepG2 cells. LSEs treatment could significantly reduce APAP-induced HepG2 apoptosis assessed by DAPI and Annexin V/PI. The further molecule mechanisms indicated that LSEs decreased Fas/FasL binding and reduced Bax and tBid to restore mitochondrial structure and subsequently suppress downstream apoptosis cascade activation. These declines in COX-2, NF-κB, and iNOS levels were observed in co-treatment APAP and LSEs, which indicated that LSEs could ameliorate APAP-induced inflammation. LSE protected APAP-induced apoptosis by preventing extrinsic, intrinsic, and JNK-mediated pathways. In addition, the restoration of mitochondria and inflammatory suppression in LSEs treatments indicated that LSEs could decrease oxidative stress induced by toxic APAP. Therefore, LSE could be a novel therapeutic option for an antidote against overdose of APAP.

Comprehensive Analysis for GRF Transcription Factors in Sacred Lotus (Nelumbo nucifera).

Sacred lotus (Nelumbo nucifera) is an aquatic perennial plant with essential food, ornamental, and pharmacological value. Growth-regulating factor (GRF) is a transcription factor (TF) family that plays an important role in regulating the growth and development of plants. In this study, a comprehensive analysis of the GRF family in N. nucifera was performed, and its role in N. nucifera development was studied. A total of eight GRF genes were identified in the N. nucifera genome. Phylogenetic analysis divided the 38 GRF genes into six clades, while the NuGRFs only contained five clades. The analyses of gene structures, motifs, and cis-acting regulatory elements of the GRF gene family were performed. In addition, the chromosome location and collinearity were analyzed. The expression pattern based on transcriptomic data and real-time reverse transcription-quantitative PCR (qRT-PCR) revealed that the GRF genes were expressed in multiple organs and were abundant in actively growing tissues, and the expression levels decreased as the age of N. nucifera increased. Then, 3D structures of the NuGRF proteins were predicted by homology modeling. Finally, the subcellular localization of GRF1 was ascertained in the tobacco leaf through a vector. Therefore, this study provides a comprehensive overview of the GRF TF family in N. nucifera.

Enzymatic basis for stepwise C-glycosylation in the formation of flavonoid di-C-glycosides in sacred lotus (Nelumbo nucifera Gaertn.).

Lotus plumule, the embryo of the seed of the sacred lotus (Nelumbo nucifera), contains a high accumulation of secondary metabolites including flavonoids and possesses important pharmaceutical value. Flavonoid C-glycosides, which accumulate exclusively in lotus plumule, have attracted considerable attention in recent decades due to their unique chemical structure and special bioactivities. As well as mono-C-glycosides, lotus plumule also accumulates various kinds of di-C-glycosides by mechanisms which are as yet unclear. In this study we identified two C-glycosyltransferase (CGT) genes by mining sacred lotus genome data and provide in vitro and in planta evidence that these two enzymes (NnCGT1 and NnCGT2, also designated as UGT708N1 and UGT708N2, respectively) exhibit CGT activity. Recombinant UGT708N1 and UGT708N2 can C-glycosylate 2-hydroxyflavanones and 2-hydroxynaringenin C-glucoside, forming flavone mono-C-glycosides and di-C-glycosides, respectively, after dehydration. In addition, the above reactions were successfully catalysed by cell-free extracts from tobacco leaves transiently expressing NnCGT1 or NnCGT2. Finally, enzyme assays using cell-free extracts of lotus plumule suggested that flavone di-C-glycosides (vicenin-1, vicenin-3, schaftoside and isoschaftoside) are biosynthesized through sequentially C-glucosylating and C-arabinosylating/C-xylosylating 2-hydroxynaringenin. Taken together, our results provide novel insights into the biosynthesis of flavonoid di-C-glycosides by proposing a new biosynthetic pathway for flavone C-glycosides in N. nucifera and identifying a novel uridine diphosphate-glycosyltransferase (UGT708N2) that specifically catalyses the second glycsosylation, C-arabinosylating and C-xylosylating 2-hydroxynaringenin C-glucoside.

Effect of ultraviolet treatment on shelf life of fresh lotus root.

The potential use of ultraviolet (UV)-C (254 nm) to extend postharvest shelf life of fresh unprocessed lotus root (Nelumbo nucifera G.) was determined. UV treatment for 30 and 60 min effectively reduced weight loss, improved moisture, color retention, and soluble solids of samples when stored at 25°C for 15 days. Microbial growth inhibition of UV was evidenced by 1.8 and 1.0 log reductions in the 30 and 60 min-treated samples. Phenylalanine ammonia lyase (PAL) activity and total phenol contents (TPCs) detected in lotus root were higher, while oxidative enzymes peroxidase (POD) and polyphenol oxidase (PPO) were inhibited by UV treatment. Gallic acid, gallocatechin, and catechin levels were increased in 30 min-treated samples by about 0.9, 13.4, 8.0 mg/100 g. The results suggest that extension of postharvest storage life by UV-C is most likely through the protective roles exerted from stimulation of the phenylpropanoid pathway in the treated roots. PRACTICAL APPLICATIONS: Unlike previous studies that are mainly focused on shelf life extension of processed products of the rhizome, this study determines the potential use of a nonchemical and ecologically friendly ultraviolet (UV-C) treatment to extend shelf life of intact uncut fresh lotus root. Our results demonstrated that UV-C treatment significantly prolonged the shelf life of lotus root. Use of this method is promising as a treatment to improve postharvest storage life of fresh lotus root, to improve its export potential and help to address unmet local demands for the crop.

Effect of postharvest oxalic acid application on enzymatic browning and quality of lotus (Nelumbo nuciferaGaertn.) root slices.

Post-cut surface browning is one of the major constraints for shelf-life extension of lotus root slices. In the present study, lotus roots slices were treated with 0, 5 and 10 mmol L-1 oxalic acid and stored at 20 ± 1 °C for 5 days. Results showed that 10 mmol L-1 oxalic acid treated lotus slices exhibited reduced browning, superoxide anion, hydrogen peroxide, electrolyte leakage and malondialdehyde content than control. The 10 mmol L-1 treated slices had better visual quality and higher ascorbic acid and total phenolic contents. In addition, 10 mmol L-1 treated slices showed reduced total bacterial count along with lower soluble quinones, peroxidase and polyphenol oxidase activities in contrast to control. Similarly, 10 mmol L-1 treatment showed higher superoxide dismutase, catalase and ascorbate peroxidase activities as compared to control. In conclusion, 10 mmol L-1 oxalic acid application could be considered suitable to delay post-cut browning of lotus root slices.

Isolation and characterization of two O-methyltransferases involved in benzylisoquinoline alkaloid biosynthesis in sacred lotus (Nelumbo nucifera).

Benzylisoquinoline alkaloids (BIAs) are a major class of plant metabolites with many pharmacological benefits. Sacred lotus (Nelumbo nucifera) is an ancient aquatic plant of medicinal value because of antiviral and immunomodulatory activities linked to its constituent BIAs. Although more than 30 BIAs belonging to the 1-benzylisoquinoline, aporphine, and bisbenzylisoquinoline structural subclasses and displaying a predominant R-enantiomeric conformation have been isolated from N. nucifera, its BIA biosynthetic genes and enzymes remain unknown. Herein, we report the isolation and biochemical characterization of two O-methyltransferases (OMTs) involved in BIA biosynthesis in sacred lotus. Five homologous genes, designated NnOMT1-5 and encoding polypeptides sharing >40% amino acid sequence identity, were expressed in Escherichia coli Functional characterization of the purified recombinant proteins revealed that NnOMT1 is a regiospecific 1-benzylisoquinoline 6-O-methyltransferase (6OMT) accepting both R- and S-substrates, whereas NnOMT5 is mainly a 7-O-methyltransferase (7OMT), with relatively minor 6OMT activity and a strong stereospecific preference for S-enantiomers. Available aporphines were not accepted as substrates by either enzyme, suggesting that O-methylation precedes BIA formation from 1-benzylisoquinoline intermediates. Km values for NnOMT1 and NnOMT5 were 20 and 13 µm for (R,S)-norcoclaurine and (S)-N-methylcoclaurine, respectively, similar to those for OMTs from other BIA-producing plants. Organ-based correlations of alkaloid content, OMT activity in crude extracts, and OMT gene expression supported physiological roles for NnOMT1 and NnOMT5 in BIA metabolism, occurring primarily in young leaves and embryos of sacred lotus. In summary, our work identifies two OMTs involved in BIA metabolism in the medicinal plant N. nucifera.

Benzylisoquinoline Alkaloids Biosynthesis in Sacred Lotus.

Sacred lotus (Nelumbo nucifera Gaertn.) is an ancient aquatic plant used throughout Asia for its nutritional and medicinal properties. Benzylisoquinoline alkaloids (BIAs), mostly within the aporphine and bisbenzylisoquinoline structural categories, are among the main bioactive constituents in the plant. The alkaloids of sacred lotus exhibit promising anti-cancer, anti-arrhythmic, anti-HIV, and anti-malarial properties. Despite their pharmacological significance, BIA metabolism in this non-model plant has not been extensively investigated. In this review, we examine the diversity of BIAs in sacred lotus, with an emphasis on the distinctive stereochemistry of alkaloids found in this species. Additionally, we discuss our current understanding of the biosynthetic genes and enzymes involved in the formation of 1-benzylisoquinoline, aporphine, and bisbenzylisoquinoline alkaloids in the plant. We conclude that a comprehensive functional characterization of alkaloid biosynthetic enzymes using both in vitro and in vivo methods is required to advance our limited knowledge of BIA metabolism in the sacred lotus.

Nelumbo Nucifera leaf protects against UVB-induced wrinkle formation and loss of subcutaneous fat through suppression of MCP3, IL-6 and IL-8 expression.

Nelumbo nucifera has long been used in traditional medicine in East Asian countries such as China and Korea. In this study, we report the different property of several Nelumbo nucifera leaf (NNL) extracts on adipocyte differentiation. Adipogenesis was stimulated by administration of dichloromethyl (DCM) or n-hexan extract of NNL but attenuated by that of water extract. We also show that topical administration of DCM extract of NNL attenuated ultraviolet-B (UVB)-mediated wrinkle formation and reduction of subcutaneous (SC) fat in vivo. Interestingly, UVB-induced blood contents of triglyceride (TG) were attenuated significantly by topical administration of the DCM extract. In addition, we found that UVB-induced expression of cytokines (interleukin-6; IL-6, interleukin-8; IL-8, and monocyte chemotactic protein-3; MCP3), which were reported as regulators in SC fat metabolism, was attenuated in mouse skin fibroblast cells upon administration of the DCM extract. Collectively, our data suggest that topical administration of DCM extract of NNL, which plays a regulatory role in adipogenesis, could attenuate UVB-induced wrinkle formation and the metabolism of blood lipids by regulating the expression of cytokines such as IL-6, IL-8, and MCP3 in skin fibroblast cells. Our findings support further development of DCM extract of NNL as a potential therapeutic agent for prevention of photoaging-related disorders.

Induction and quantitative proteomic analysis of cell dedifferentiation during callus formation of lotus (Nelumbo nucifera Gaertn.spp. baijianlian).

Lotus is an aquatic plant with high nutritional, ornamental and medical values. Its callus formation is crucial for germplasm innovation by genetic transformation. In this study, embryogenic callus was successfully induced on appropriate medium using cotyledons at 12days after pollination as explants. To dissect cellular dedifferentiation and callus formation processes at the proteome level, cotyledons before and tissues from 10 to 20days after induction were sampled for shotgun proteomic analysis. By applying multivariate statistics 91 proteins were detected as differentially regulated, and sorted into 6 functional groups according to MapMan ontology analysis. Most of these proteins were implicated in various metabolisms, demonstrating that plant cells underwent metabolism reprogramming during callus induction. 14.3% proteins were associated with stress and redox, indicating that the detached explants were subjected to a variety of stresses; 13.2% were cell and cell wall-related proteins, suggesting that these proteins played important roles in rapid cell division and proliferation. Some proteins were further evaluated at the mRNA levels by quantitative reverse transcription PCR analysis. In conclusion, the results contributed to further deciphering of molecular processes of cellular dedifferentiation and callus formation, and provided a reference data set for the establishment of transgenic transformation in lotus.

Green synthesized silver nanoparticles using Nelumbonucifera root extract for efficient protein binding, antioxidant and cytotoxicity activities.

Silver nanoparticles (AgNPs) with a mean particle size of ∼ 16.7 nm were synthesized using an eco-friendly reducing material, aqueous Nelumbo nucifera root extract. Rapid reduction resulted in the formation of polydispersed nanoparticles. The formation of AgNPs was characterized by surface plasmon resonance, which was determined by ultraviolet-visible (UV-Vis) spectroscopy (band at 412 nm), Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction. The interaction of the green synthesized AgNPs with Bovine Serum Albumin (BSA) at various temperatures was investigated. Fluorescence quenching, synchronous and resonance light scattering spectroscopy along with UV-Vis absorption studies revealed the efficient binding between BSA and the AgNPs. In addition, the AgNPs exhibited moderate antioxidant and cytotoxicity activities against HeLa cell lines.

Isolation and functional characterization of a salt responsive transcriptional factor, LrbZIP from lotus root (Nelumbo nucifera Gaertn).

Basic leucine zipper transcription factor (bZIP) is involved in signaling transduction for various stress responses. Here we reported a bZIP transcription factor (accession: JX887153) isolated from a salt-resistant lotus root using cDNA-AFLP approach with RT-PCR and RACE-PCR method. Full-length cDNA which consisted of a single open reading frame encoded a putative polypeptide of 488 amino acids. On the basis of 78, 76, and 75 % sequence similarity with the bZIPs from Medicago truncatula (XP_003596814.1), Carica papaya (ABS01351.1) and Arabidopsis thaliana (NP_563810.2), we designed it as LrbZIP. Semi quantitative RT-PCR results, performed on the total RNA extracted from tips of lotus root, showed that LrbZIP expression was increased with 250 mM NaCl treatment for 18 h. Effects of low temperature on the expression of LrbZIP was also studied, and its expression was significantly enhanced with a 4 °C treatment for 12 h. In addition, LrbZIP expression was strongly induced by treatment with exogenous 100 µM ABA. To evaluate its function across the species, tobacco (Nicotiana tabacum L.) was transformed with LrbZIP in a binary vector construct. Transgenic plants exhibited higher resistance as compared with the control according to the results of the root growth, chlorophyll content and electrolyte leakage when exposed to NaCl treatment. In addition, LrCDPK2, LrLEA, and TPP also showed enhanced expression in the transgenic plants. Overall, expression of LrbZIP was probably very important for salt-resistant lotus root to survive through salt stress.

Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis.

Metallothioneins (MTs) are small, cysteine-rich and metal-binding proteins which are involved in metal homeostasis and scavenging of reactive oxygen species. Although plant MTs have been intensively studied, their roles in seeds remain to be clearly established. Here, we report the isolation and characterization of NnMT2a, NnMT2b and NnMT3 from sacred lotus (Nelumbo nucifera Gaertn.) and their roles in seed germination vigor. The transcripts of NnMT2a, NnMT2b and NnMT3 were highly expressed in developing and germinating sacred lotus seeds, and were dramatically up-regulated in response to high salinity, oxidative stresses and heavy metals. Analysis of transformed Arabidopsis protoplasts showed that NnMT2a-YFP and NnMT3-YFP were localized in cytoplasm and nucleoplasm. Transgenic Arabidopsis seeds overexpressing NnMT2a and NnMT3 displayed improved resistance to accelerated aging (AA) treatment, indicating their significant roles in seed germination vigor. These transgenic seeds also exhibited higher superoxide dismutase activity compared to wild-type seeds after AA treatment. In addition, we showed that NnMT2a and NnMT3 conferred improved germination ability to NaCl and methyl viologen on transgenic Arabidopsis seeds. Taken together, these data demonstrate that overexpression of NnMT2a and NnMT3 in Arabidopsis significantly enhances seed germination vigor after AA treatment and under abiotic stresses.

Remediation of cadmium contaminated irrigation and drinking water: a large scale approach.

Cadmium is one of the most troublesome toxic heavy metals. It accumulates in the water reservoirs and agricultural soil as a result of intensive use of Cd contaminated phosphate fertilizers, e.g. in agriculture in the North Central Province (NCP) of Sri Lanka. The hyper-accumulator Thlaspi caerulescens, accumulates up to 1000 ppm Cd in shoots without exhibiting toxicity symptoms. The storage rhizomes of year old Nelumbo nucifera (lotus) natural vegetation in water reservoirs in NCP accumulated 253+/-12 mg Cd/kg. Seedlings of lotus grown in 5% Hoagland's solution at 0.75, 1.0 and 1.25 ppm cadmium sulphate showed a significant increase in Cd removal of 0.0334-0.121 ppm/week. However the removal rate of Cd from water failed to increase any further at higher concentrations of Cd in water. The slow growth rate and low rate of phytoextraction demands a more effective but an affordable method of remediation in order to combat the prevailing elevated cadmium levels in NCP that causes chronic renal failure (CRF). We have developed a large scale filtering device using rice husk. We have achieved successful results in sequestering Cd using raw rice husk as well as amorphous silica derived from rice husk.