Nitric oxide-induced salt stress tolerance in plants: ROS metabolism,signaling, and molecular interactions

Nitric oxide (NO), a non-charged, small, gaseous free-radical, is a signaling molecule in all plant cells. Several studies have proposed multifarious physiological roles for NO, from seed germination to plant maturation and senescence. Nitric oxide is thought to act as an antioxidant, quenching ROS during oxidative stress and reducing lipid peroxidation. NO also mediates photosynthesis and stomatal conductance and regulates programmed cell death, thus providing tolerance to abiotic stress. In mitochondria, NO participates in the electron transport pathway. Nitric oxide synthase and nitrate reductase are the key enzymes involved in NO-biosynthesis in aerobic plants, but non-enzymatic pathways have been reported as well. Nitric oxide can interact with a broad range of molecules, leading to the modification of protein activity, GSH biosynthesis, S-nitrosylation, peroxynitrite formation, proline accumulation, etc., to sustain stress tolerance. In addition to these interactions, NO interacts with fatty acids to form nitro-fatty acids as signals for antioxidant defense. Polyamines and NO interact positively to increase polyamine content and activity. A large number of genes are reprogrammed by NO; among these genes, proline metabolism genes are upregulated. Exogenous NO application is also shown to be involved in salinity tolerance and/or resistance via growth promotion, reversing oxidative damage and maintaining ion homeostasis. This review highlights NO-mediated salinity-stress tolerance in plants, including NO biosynthesis, regulation, and signaling. Nitric oxide-mediated ROS metabolism, antioxidant defense, and gene expression and the interactions of NO with other bioactive molecules are also discussed. We conclude the review with a discussion of unsolved issues and suggestions for future research.     

Indole alkaloids from the seeds of Centaurea cyanus (Asteraceae).

Preparative RP-HPLC analysis of a methanol extract of the seeds of Centaurea cyanus afforded four indole alkaloids: moschamine, cis-moschamine, centcyamine and cis-centcyamine, the latter two being new natural products. Structures of these compounds were elucidated by comprehensive spectroscopic analyses. General toxicity of the isolates was determined by Brine Shrimp Lethality bioassay.     

Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis,antioxidant defense and glyoxalase systems

Hydroponically grown 12-day-old rice (Oryza sativa L. cv. BRRI dhan47) seedlings were exposed to 150 mM NaCl alone and combined with 0.5 mM MnSO₄. Salt stress resulted in disruption of ion homeostasis by Na⁺ influx and K⁺ efflux. Higher accumulation of Na⁺ and water imbalance under salinity caused osmotic stress, chlorosis, and growth inhibition. Salt-induced ionic toxicity and osmotic stress consequently resulted in oxidative stress by disrupting the antioxidant defense and glyoxalase systems through overproduction of reactive oxygen species (ROS) and methylglyoxal (MG), respectively. The salt-induced damage increased with the increasing duration of stress. However, exogenous application of manganese (Mn) helped the plants to partially recover from the inhibited growth and chlorosis by improving ionic and osmotic homeostasis through decreasing Na⁺ influx and increasing water status, respectively. Exogenous application of Mn increased ROS detoxification by increasing the content of the phenolic compounds, flavonoids, and ascorbate (AsA), and increasing the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and catalase (CAT) in the salt-treated seedlings. Supplemental Mn also reinforced MG detoxification by increasing the activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) in the salt-affected seedlings. Thus, exogenous application of Mn conferred salt-stress tolerance through the coordinated action of ion homeostasis and the antioxidant defense and glyoxalase systems in the salt-affected seedlings.     

Development of restoration techniques for Hawaiian thrushes: Collection of wild eggs,artificial incubation,hand‐rearing,captive‐breeding,and re‐introduction to the wild

From 1995 to 1999, two species of endemic Hawaiian thrushes, `Oma`o (Myadestes obscurus) and Puaiohi (M. palmeri), were captive‐reared and re‐introduced into their historic range in Hawai`i by The Peregrine Fund, in collaboration with the U.S. Geological Survey–Biological Resources Division (BRD) and the Hawai`i State Department of Land and Natural Resources. This paper describes the management techniques that were developed (collection of wild eggs, artificial incubation, hand‐rearing, captive propagation, and release) with the non‐endangered surrogate species, the `Oma`o; techniques that are now being used for recovery of the endangered Puaiohi. In 1995 and 1996, 29 viable `Oma`o eggs were collected from the wild. Of 27 chicks hatched, 25 were hand‐reared and released into Pu`u Wa`awa`a Wildlife Reserve. Using the techniques developed for the `Oma`o, a captive propagation and release program was initiated in 1996 to aid the recovery of the endangered Puaiohi. Fifteen viable Puaiohi eggs were collected from the wild (1996–1997) to establish a captive breeding flock to produce birds for re‐introduction. These Puaiohi reproduced for the first time in captivity in 1998 (total Puaiohi chicks reared in captivity 1996–1998 = 41). In 1999, 14 captive‐bred Puaiohi were re‐introduced into the Alaka`i Swamp, Kaua`i. These captive‐bred birds reproduced and fledged seven chicks in the wild after release. This is the first endangered passerine recovery program using this broad spectrum of management techniques (collection of wild eggs, artificial incubation, hand‐rearing, captive‐breeding, and release) in which re‐introduced birds survived and bred in the wild. Long‐term population monitoring will be published separately [BRD, in preparation]. Zoo Biol 19:263–277, 2000. © 2000 Wiley‐Liss, Inc.     

Application of Cyanidin-3-Glucosides as a functional food ingredient in rice-based bakery products

BackgroundBlack pericarp rice has recently become popular among rice consumers for its diverse health benefits specially anti-cancer effect. Cyanidin-3-Glucosides (C3G), an prominant bioactive component of anthocyanins which is abundantly present in black pericarp rice.ObjectivesWe investigated, how effectively it can be used to fortify Cyanidin-3-Glucosides (C3G) content in red and white pericarp polished rice or rice based bakery products for more nutritional value.MethodIn the present study, we have characterized several black pericarp rice cultivars along with some red pericarp and white pericarp rice cultivars by physicochemical including mineral profiling, and quantified the C3G by UFLC and LCMS.ResultsC3G content was significantly reduced from raw rice to cooked rice condition. All the black pericarp rice cultivars synthesized C3G, while this content was not detected in red and white pericarp rice cultivars. However, when 25% of black pericarp rice were mixed with 75% red or white pericarp polished rice, C3G content was significantly retained in cooked rice conditions. Formulation of rice-based bakery food product using black pericarp rice powder was also remarkably retained the C3G content as compared to that of cooking. Black rice is harder in texture, difficult to digest and needs higher energy for cooking. Therefore, we tried to circumvent these challenges by fortifying 25% of black pericarp rice with white or red pericarp rice.ConclusionFortification of C3G enriched black rice (25%) with red or white pericarp rice (75%) might bring a better nutritional quality in both cooking and baking condition. This may lead a way to the effective management of the non-communicable disease such as cancer for common rice consuming population.     

Biochemical and morphological attributes of broiler kidney in response to dietary glucocorticoid,dexamethasone

Glucocorticoids (GCs) initiate oxidative stress and cause renal damage which lead to hypertension, heart failure and ultimately death. The current study aimed to investigate the alterations in serum biochemical parameters i.e. HDL and LDL; gross anatomy, histomorphology and histomorphometry of broiler kidney in response to dietary GC, dexamethasone (DEX). Day old chicks (DOCs) were randomly assigned into four groups: control and three treatment groups (T1, T2 and T3). The control group was fed commercial broiler type ration and the treated groups were fed commercial broiler type ration containing GC (Dexamethasone @ 3, 5 and 7 mg/kg in T1, T2 and T3 group respectively). To measure the biochemical parameters, blood samples were collected on days 7, 14, 21, and 28 of the experiment. For histological investigation, kidney (left) samples were collected from the individual birds after sacrificing on days 7, 14, 21, and 28 of the experiment. Histomorphological alterations of the kidney were assessed by routine hematoxylin and eosin (H&E) staining. Biochemical analysis showed significantly increased serum HDL and LDL level compared to the control. In gross study, dark congested kidney was found with significantly decreased weight, length and width. Treatment with DEX augmented congestion, inflammation and fibrosis in kidney, as evidence by histomorphometric study. Extensively degenerated and atrophied glomeruli, degenerated tubular epithelium with distorted tubules and inter tubular empty spaces were seen. Percentage of atrophied glomeruli increased significantly and maximum percentage of glomerular atrophy was seen at day 28. These changes were found more explicitly in the higher dose group. Histomorphometric study also revealed significant decrease in the diameter of glomerulus. The findings of this study suggest that DEX may alter the serum biochemical parameters as well as kidney gross and histomorphology.     

Bioactive aristolactams from Piper umbellatum

Four alkaloids named piperumbellactams A-D (1-4) were isolated from branches of Piper umbellatum together with known N-hydroxyaristolam II (5), N-p-coumaroyl tyramine (6), 4-nerolidylcatechol (7), N-trans-feruloyltyramine, E-3-(3,4-dihydroxyphenyl)-N-2-[4-hydroxyphenylethyl]-2-propenamide, beta-amyrin, friedelin, apigenin 8-C-neohesperidoside, acacetin 6-C-beta-d-glucopyranoside, beta-sitosterol, its 3-O-beta-d-glucopyranoside and its 3-O-beta-d-[6'-dodecanoyl]-glucopyranoside. Glycosidase inhibition, antioxidant and antifungal activities of these compounds were evaluated. Compounds 1-3 showed moderate alpha-glucosidase enzyme inhibition with IC50 values 98.07+/-0.44, 43.80+/-0.56 and 29.64+/-0.46, respectively. In DPPH radical scavenging assay, compounds 2, 3 and 6 showed potent inhibitory activity while compounds 4, 5 and 7 showed potent antifungal activity.     

Cluster of Nipah virus infection, Kushtia District, Bangladesh, 2007

Objective

In March 2007, we investigated a cluster of Nipah encephalitis to identify risk factors for Nipah infection in Bangladesh.

Methods

We defined confirmed Nipah cases by the presence of IgM and IgG antibodies against Nipah virus in serum. Case-patients, who resided in the same village during the outbreak period but died before serum could be collected, were classified as probable cases.

Results

We identified three confirmed and five probable Nipah cases. There was a single index case. Five of the secondary cases came in close physical contact to the index case when she was ill. Case-patients were more likely to have physical contact with the index case (71% cases versus 0% controls, p = <0.001). The index case, on her third day of illness, and all the subsequent cases attended the same religious gathering. For three probable cases including the index case, we could not identify any known risk factors for Nipah infection such as physical contact with Nipah case-patients, consumption of raw date palm juice, or contact with sick animals or fruit bats.

Conclusion

Though person-to-person transmission remains an important mode of transmission for Nipah infection, we could not confirm the source of infection for three of the probable Nipah case-patients. Continued surveillance and outbreak investigations will help better understand the transmission of Nipah virus and develop preventive strategies.