Golgi-localized cation/proton exchangers regulate ionic homeostasis and skotomorphogenesis in Arabidopsis.

Multiple transporters and channels mediate cation transport across the plasma membrane and tonoplast to regulate ionic homeostasis in plant cells. However, much less is known about the molecular function of transporters that facilitate cation transport in other organelles such as Golgi. We report here that Arabidopsis KEA4, KEA5, and KEA6, members of cation/proton antiporters-2 (CPA2) superfamily were colocalized with the known Golgi marker, SYP32-mCherry. Although single kea4,5,6 mutants showed similar phenotype as the wild type under various conditions, kea4/5/6 triple mutants showed hypersensitivity to low pH, high K+ , and high Na+ and displayed growth defects in darkness, suggesting that these three KEA-type transporters function redundantly in controlling etiolated seedling growth and ion homeostasis. Detailed analysis indicated that the kea4/5/6 triple mutant exhibited cell wall biosynthesis defect during the rapid etiolated seedling growth and under high K+ /Na+ condition. The cell wall-derived pectin homogalacturonan (GalA)3 partially suppressed the growth defects and ionic toxicity in the kea4/5/6 triple mutants when grown in the dark but not in the light conditions. Together, these data support the hypothesis that the Golgi-localized KEAs play key roles in the maintenance of ionic and pH homeostasis, thereby facilitating Golgi function in cell wall biosynthesis during rapid etiolated seedling growth and in coping with high K+ /Na+ stress.

SmCOI1 affects anther dehiscence in a male-sterile Solanum melongena line.

Anther indehiscence is an important form of functional male sterility that can facilitate the production of hybrid seed; however, the molecular mechanisms of anther indehiscence-based male sterility have not been thoroughly explored in eggplant (Solanum melongena L.). Here, we used two-dimensional gel electrophoresis to compare the protein profiles in the anthers of normally developing (F142) and anther indehiscent (S16) S. melongena plants. Four differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Of these proteins, the transcript accumulation of the eggplant CORONATINE INSENSITIVE1 (SmCOI1) was significantly downregulated in S16 relative to F142. Phylogenetic analysis showed that SmCOI1 has high amino acid sequence similarity and clustered into the same subgroup as its homologs in other members of the Solanaceae. Subcellular localization analysis showed that SmCOI1 localized to the nucleus. Moreover, reverse-transcription quantitative PCR revealed that the jasmonic acid pathway genes SmJAZ1 and SmOPR3 are upregulated in F142 relative to S16. Protein-protein interaction studies identified a direct interaction between SmCOI1 and SmOPR3, but SmCOI1 failed to interact with SmJAZ1. These findings shed light on the regulatory mechanisms of anther dehiscence in eggplant.

AGL18-1 delays flowering time through affecting expression of flowering-related genes in Brassica juncea.

Brassica juncea is an important vegetable and condiment crop widely grown in Asia, and the yield and quality of its product organs are affected by flowering time. AGAMOUS-LIKE18-1 (AGL18-1) belongs to a member of MADS-domain transcription factors, which play vital roles in flowering time control, but the biological role of AGL18-1 in B. juncea (BjuAGL18-1) has not been thoroughly revealed in flowering regulatory network. In this study, BjuAGL18-1 expressed highly in inflorescence and flower, but slightly in root, stem and leaf. The sense and anti-sense transgenic lines of BjuAGL18-1 were generated and showed that BjuAGL18-1 functioned as a flowering inhibitor and depressed growth of lateral branching. During the vegetative phase, BjuAGL18-1 induced another flowering repressor AGAMOUS-LIKE15 (BjuAGL15) but inhibited the flowering signal integrator of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (BjuSOC1) in Brassica juncea. Whereas, during the flower developmental phase, both SOC1 and AGAMOUS-LIKE24 (AGL24) were down-regulated by BjuAGL18-1. By contrast, AGL15 was promoted by BjuAGL18-1, while SHORT VEGETATIVE PHASE (SVP) was independent of BjuAGL18-1. Additionally, HISTONE DEACETYLASE 9 (HDA9) was highly induced by BjuAGL18-1. These results will provide valuable information for clarifying the molecular mechanism of BjuAGL18-1 in mediating flowering time.

Magnesium Transporter MGT6 Plays an Essential Role in Maintaining Magnesium Homeostasis and Regulating High Magnesium Tolerance in Arabidopsis.

Magnesium (Mg) is one of the essential nutrients for all living organisms. Plants acquire Mg from the environment and distribute within their bodies in the ionic form via Mg2+-permeable transporters. In Arabidopsis, the plasma membrane-localized magnesium transporter MGT6 mediates Mg2+ uptake under Mg-limited conditions, and therefore is important for the plant adaptation to low-Mg environment. In this study, we further assessed the physiological function of MGT6 using a knockout T-DNA insertional mutant allele. We found that MGT6 was required for normal plant growth during various developmental stages when the environmental Mg2+ was low. Interestingly, in addition to the hypersensitivity to Mg2+ limitation, mgt6 mutants displayed dramatic growth defects when external Mg2+ was in excess. Compared with wild-type plants, mgt6 mutants generally contained less Mg2+ under both low and high external Mg2+ conditions. Reciprocal grafting experiments further underpinned a role of MGT6 in a shoot-based mechanism for detoxifying excessive Mg2+ in the environment. Moreover, we found that mgt6 mgt7 double mutant showed more severe phenotypes compared with single mutants under both low- and high-Mg2+ stress conditions, suggesting that these two MGT-type transporters play an additive role in controlling plant Mg2+ homeostasis under a wide range of external Mg2+ concentrations.

Cognitive-behavioral therapy for the management of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a common disorder, reported to be found in 5%-20% of the general population. Its management accounts for up to 25% of a gastroenterologist's workload in the outpatient department, and the main symptoms are abdominal pain, bloating, and altered bowel habits. Despite a great amount of available pharmacological treatments aimed at a wide variety of gastrointestinal and brain targets, many patients have not shown adequate symptom relief. In recent years, there has been increasing evidence to suggest that psychological treatments, in particular cognitive-behavioral therapy (CBT), are effective for the management of IBS. This review discusses CBT for the management of IBS. CBT has proved to be effective in alleviating the physical and psychological symptoms of IBS and has thus been recommended as a treatment option for the syndrome.

Antinociceptive effect of berberine on visceral hypersensitivity in rats.

AIM: To assess the protective effect of berberine administration and the role of nitric oxide (NO) in visceral hypersensitivity. METHODS: Fifty male Sprague-Dawley rats were randomly assigned to five groups. An inflammatory bowel disease model was induced in rats by intracolonic instillation of 1 mL 4% acetic acid at 8 cm proximal to the anus for 30 s and restraint stress. After subsidence of inflammation on day 7 of the experiment, the rats were subjected to rectal distension, performed by a balloon (6-Fr, 2 mm external diameter, disposable silicon balloon-urethral catheter for pediatric use) which was rapidly inflated with increasing volumes of prewarmed (37 °C) water (0.1, 0.2, 0.3, 0.4, 0.6, 0.8 and 1 mL) for 30 s at four-minute intervals, and then the abdominal withdrawal reflex (AWR) and the level of fecal output were measured, respectively. AWR scores either 0, 1, 2, 3 or 4 were obtained by blinded observers. Rats had been pretreated with berberine or aminoguanidine (NO synthetase inhibitor) or berberine + aminoguanidine before measurement. RESULTS: The rats in the placebo group showed a hypersensitive response to rectal distension (2.69 ± 0.08 vs 1.52 ± 0.08, P = 0.000) and defecated more frequently than those in the control group (5.0 ± 0.16 vs 0.44 ± 0.16, P = 0.000). Comparing the berberine with placebo group, the AWR scores were reduced for all distension volumes and were significant at 0.2-1 mL (1.90 ± 0.08 vs 2.69 ± 0.08, P = 0.000), while the numbers of hard pellets, soft pellets, formless stools, and total fecal output in the placebo group were significantly larger than in the berberine group (5.0 ± 0.16 vs 2.56 ± 0.16, P = 0.000). Administration of aminoguanidine or berberine + aminoguanidine before VH score measurement reversed the antinociceptive effect of berberine (2.52 ± 0.08 vs 1.90 ± 0.08, P = 0.000; 2.50 ± 0.08 vs 1.90 ± 0.08, P = 0.000). The numbers of hard pellets, soft pellets, formless stool, and total of fecal output in aminoguanidine group were significantly larger than the corresponding values in control group, berberine group, and berberine + aminoguanidine group (4.81 ± 0.16 vs 0.44 ± 0.16, P = 0.000; 4.81 ± 0.16 vs 2.56 ± 0.16, P = 0.000; 4.81 ± 0.16 vs 3.75 ± 0.16, P = 0.000). The berberine and berberine + aminoguanidine groups showed reduced defecation, but aminoguanidine alone did not reduce defecation (2.56 ± 0.16 vs 4.81 ± 0.16, P = 0.000; 3.75 ± 0.16 vs 4.81 ± 0.16, P = 0.000). CONCLUSION: Berberine had an antinociceptive effect on visceral hypersensitivity, and NO might play a role in this effect.