Transcriptome Profiling and Characterization of Drought-Tolerant Potato Plant (Solanum tuberosum L.).

Potato (Solanum tuberosum L.) is the third most important food crop, and breeding drought-tolerant varieties is vital research goal. However, detailed molecular mechanisms in response to drought stress in potatoes are not well known. In this study, we developed EMS-mutagenized potatoes that showed significant tolerance to drought stress compared to the wild-type (WT) 'Desiree' cultivar. In addition, changes to transcripts as a result of drought stress in WT and drought-tolerant (DR) plants were investigated by de novo assembly using the Illumina platform. One-week-old WT and DR plants were treated with -1.8 Mpa polyethylene glycol-8000, and total RNA was prepared from plants harvested at 0, 6, 12, 24, and 48 h for subsequent RNA sequencing. In total, 61,100 transcripts and 5,118 differentially expressed genes (DEGs) displaying up- or down-regulation were identified in pairwise comparisons of WT and DR plants following drought conditions. Transcriptome profiling showed the number of DEGs with up-regulation and down-regulation at 909, 977, 1181, 1225 and 826 between WT and DR plants at 0, 6, 12, 24, and 48 h, respectively. Results of KEGG enrichment showed that the drought tolerance mechanism of the DR plant can mainly be explained by two aspects, the 'photosynthetic-antenna protein' and 'protein processing of the endoplasmic reticulum'. We also divided eight expression patterns in four pairwise comparisons of DR plants (DR0 vs DR6, DR12, DR24, DR48) under PEG treatment. Our comprehensive transcriptome data will further enhance our understanding of the mechanisms regulating drought tolerance in tetraploid potato cultivars.

Swertisin ameliorates pre-pulse inhibition deficits and cognitive impairment induced by MK-801 in mice.

Swertisin, a plant-derived C-glucosylflavone, is known to have antidiabetic, anti-inflammatory and antioxidant effects. In the present study, we investigated in mice the effects of swertisin on glutamatergic dysfunction induced by dizocilpine (MK-801), a non-competitive N-methyl-D-aspartate receptor antagonist. In the Acoustic Startle Response test, their MK-801-induced (given 0.2 mg/kg i.p.) pre-pulse inhibition deficit was significantly attenuated by the administration of swertisin (30 mg/kg p.o.). In the Novel Object Recognition Test, the recognition memory impairments that were induced by MK-801 (0.2 mg/kg, given i.p.) were also reversed by administration of swertisin (30 mg/kg p.o.). In addition, swertisin normalized the MK-801-induced elevation of phosphorylation levels of Akt and GSK-3ß signaling molecules in the prefrontal cortex. These results indicated that swertisin may be useful in managing the symptoms of schizophrenia, including sensorimotor gating disruption and cognitive impairment, and that these behavioral outcomes may be related to Akt-GSK-3ß signaling in the prefrontal cortex.

The ethanolic extract of the Eclipta prostrata L. ameliorates the cognitive impairment in mice induced by scopolamine.

ETHNOPHARMACOLOGICAL RELEVANCE: Eclipta prostrata L. (Asteraceae) has been prescribed for whole body nourishment and nervine tonic in Asia. However, the effects of E. prostrata in learning and memory have not been fully explored. AIM OF THE STUDY: To scientifically elucidate the effects of E. prostrata on cognitive functions, we examined whether E. prostrata could ameliorate a cholinergic blockade-induced memory impairment, and we also investigated the effects of E. prostrata on the synaptic plasticity in the hippocampus. MATERIALS AND METHODS: Memory impairment was induced by scopolamine, a cholinergic muscarinic receptor antagonist. The anti-amnesic effects of the ethanolic extract of Eclipta prostrata L. (EEEP) were measured in mice by the passive avoidance, Y-maze and Morris water maze tasks. To test the effects of EEEP on synaptic plasticity, we measured long-term potentiation (LTP) in the hippocampus. We also studied several signaling molecules related to learning and memory, such as phosphorylated protein kinase B (Akt) or phosphorylated glycogen synthase kinase-3ß (GSK-3ß). RESULTS: In the passive avoidance task, EEEP (50 or 100mg/kg, p.o.) significantly ameliorated the shortened step-through latency induced by scopolamine. EEEP (100mg/kg, p.o.) also showed significant increase in alternation behavior during the Y-maze task. In the Morris water maze task, scopolamine-induced a decrease in both the swimming time within the target zone and the number of crossings where the platform had been placed were significantly reversed by EEEP (50 or 100mg/kg, p.o.). Moreover, EEEP (100µg/ml) significantly enhanced hippocampal LTP without affecting basal synaptic transmission. The administration of EEEP (100mg/kg) increased the phosphorylation levels of Akt and GSK-3ß in the hippocampal region. CONCLUSION: These results suggest that EEEP has memory-ameliorating activity against scopolamine-induced cognitive impairment and facilitates LTP in the hippocampus. This could be, at least in part, mediated by the activation of the Akt-GSK-3ß signaling pathway.

The ameliorating effect of the extract of the flower of Prunella vulgaris var. lilacina on drug-induced memory impairments in mice.

Prunella vulgaris var. lilacina is widely distributed in Korea, Japan, China, and Europe, and its flowers are used to treat inflammation in traditional Chinese medicine. In the present study, we studied the effects of the ethanolic extract of the flower of P. vulgaris var. lilacina (EEPV) on drug-induced learning and memory impairment using the passive avoidance, the Y-maze, and the Morris water maze tasks in mice. EEPV (25 or 50 mg/kg, p.o.) significantly ameliorated scopolamine-induced cognitive impairments in the passive avoidance and Y-maze tasks (P<0.05). In the Morris water maze task, EEPV (25 mg/kg, p.o.) significantly shortened escape latencies in training-trials. Furthermore, swimming times within the target zone during the probe-trial were significantly increased as compared with scopolamine-treated mice (P<0.05). In addition, the reduced latency induced by MK-801 treatment in the passive avoidance task was ameliorated by EEPV (25 mg/kg, p.o.) (P<0.05). Additionally, the ameliorating effect of EEPV on scopolamine-induced memory dysfunction was antagonized by a sub-effective dose of MK-801. These results suggest that EEPV would be useful for treating cognitive impairments induced by cholinergic dysfunction, and that it exerts its effects via NMDA receptor signaling.

Subchronic administration of rosmarinic acid, a natural prolyl oligopeptidase inhibitor, enhances cognitive performances.

It is well known that inhibition of prolyl oligopeptidase (POP) is involved in memory-related function. In this study, we observed that rosmarinic acid (RA) inhibits POP activity with an IC(50) of 63.7 microM. Subsequently, we investigated the cognitive-enhancing effects of RA employing the Morris water maze paradigm. The results demonstrated that RA is non-competitive POP inhibitor and that acute and subchronic RA treatments showed an inverted U-shaped dose-response curve in the platform crossings. Furthermore, chronic RA treatment significantly increased the platform crossings. These results suggest that RA has a cognitive-enhancing effect which may be mediated by inhibition of POP.

The memory-enhancing effects of Euphoria longan fruit extract in mice.

AIM OF THE STUDY: The fruit of Euphoria longan (Lour.) Steud. (Sapindaceae) is sweet and edible. Dried Euphoria longan fruit is prescribed as a tonic and for the treatment of forgetfulness, insomnia, or palpitations caused by fright in traditional Chinese medicine. The effects of aqueous extract of Euphoria longan fruit (ELE) on learning and memory and their underlying mechanisms were investigated. MATERIALS AND METHODS: Aqueous extract of Euphoria longan fruit (ELE) was administered to ICR mice for 14 days. Piracetam was used as a positive control for its known memory-enhancing effects. Memory performances were assessed using the passive avoidance task. The expressions of phosphorylated extracellular signal-regulated kinase (pERK) 1/2, phosphorylated cAMP response element binding protein (pCREB), brain-derived neurotrophic factor (BDNF), doublecortin (DCX) and the incorporation of 5-bromo-2-deoxyuridine (BrdU) in hippocampal dentate gyrus and CA1 regions were investigated using immunohistochemical methods. RESULTS: The step-through latency in the ELE-treated group was significantly increased compared with that in the vehicle-treated controls (P<0.05) in the passive avoidance task. Piracetam-treated group also showed enhanced cognitive performaces in the passive avoidance task. Immunohistochemical studies revealed that the number of cells immunopositive for BDNF, pCREB, or pERK 1/2 was significantly increased in the hippocampal dentate gyrus and CA1 regions after ELE treatment for 14 days (P<0.05). DCX and BrdU immunostaining also revealed that ELE significantly enhanced immature neuronal survival, but not neuronal cell proliferation in the subgranular zone of the dentate gyrus. CONCLUSIONS: The present results suggest that subchronic administration of aqueous extract of Euphoria longan fruit enhances learning and memory, and that its beneficial effects are mediated, in part, by BDNF expression and immature neuronal survival.

The neuroprotective effects of the seeds of Cassia obtusifolia on transient cerebral global ischemia in mice.

The aim of this study was to determine the mechanism underlying the neuroprotective effects of the ethanolic extract of the seeds of Cassia obtusifolia (COE) (10 or 50mg/kg/day, p.o) on transient cerebral global ischemia induced by bilateral common carotid artery occlusion (2VO) in mice. Immunohistochemical and western blot studies showed that levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the hippocampal CA1 region at 1day post-2VO were attenuated by COE (50mg/kg/day, p.o), which was administered immediately after 2VO. Furthermore, OX-42 - and glial fibrillary acidic protein (GFAP)-positive cell numbers at 4 days post-2VO were markedly attenuated by COE (50mg/kg/day, p.o) treatment for 4 days in CA1. Viable neurons detected by Nissl at 7 days post-2VO were increased by administering COE (50mg/kg/day, p.o) for 7 days. In addition, COE increased the expressions of phosphorylated cAMP response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in CA1 in naïve-control within 1 and 6h, respectively, and these expressions were also profoundly increased in 2VO-treated mice by COE at immediately post-2VO. These results suggest that the neuroprotective effects of COE are due to its anti-inflammatory effects and to its upregulation of BDNF expression and CREB phosphorylation.

Regulation of the dual specificity protein phosphatase, DsPTP1, through interactions with calmodulin.

Reversible phosphorylation is a key mechanism for the control of intercellular events in eukaryotic cells. In animal cells, Ca2+/CaM-dependent protein phosphorylation and dephosphorylation are implicated in the regulation of a number of cellular processes. However, little is known on the functions of Ca2+/CaM-dependent protein kinases and phosphatases in Ca2+ signaling in plants. From an Arabidopsis expression library, we isolated cDNA encoding a dual specificity protein phosphatase 1, which is capable of hydrolyzing both phosphoserine/threonine and phosphotyrosine residues of the substrates. Using a gel overlay assay, we identified two Ca2+-dependent CaM binding domains (CaMBDI in the N terminus and CaMBDII in the C terminus). Specific binding of CaM to two CaMBD was confirmed by site-directed mutagenesis, a gel mobility shift assay, and a competition assay using a Ca2+/CaM-dependent enzyme. At increasing concentrations of CaM, the biochemical activity of dual specificity protein phosphatase 1 on the p-nitrophenyl phosphate (pNPP) substrate was increased, whereas activity on the phosphotyrosine of myelin basic protein (MBP) was inhibited. Our results collectively indicate that calmodulin differentially regulates the activity of protein phosphatase, dependent on the substrate. Based on these findings, we propose that the Ca2+ signaling pathway is mediated by CaM cross-talks with a protein phosphorylation signal pathway in plants via protein dephosphorylation.