Strigolactones alleviate AlCl3 stress by vacuolar compartmentalization and cell wall blocking in apple.

Poor management and excess fertilization of apple (Malus domestica Borkh.) orchards are causing increasingly serious soil acidification, resulting in Al toxicity and direct poisoning of roots. Strigolactones (SLs) are reported to be involved in plant responses to abiotic stress, but their role and mechanism under AlCl3 stress remain unknown. Here, we found that applying 1 µm GR24 (an SL analoge) significantly alleviated AlCl3 stress of M26 apple rootstock, mainly by blocking the movement of Al through cell wall and by vacuolar compartmentalization of Al. RNA-seq analysis identified the core transcription factor gene MdWRKY53, and overexpressing MdWRKY53 enhanced AlCl3 tolerance in transgenic apple plants through the same mechanism as GR24. Subsequently, we identified MdPMEI45 (encoding pectin methylesterase inhibitor) and MdALS3 (encoding an Al transporter) as downstream target genes of MdWRKY53 using chromatin immunoprecipitation followed by sequencing (ChIP-seq). GR24 enhanced the interaction between MdWRKY53 and the transcription factor MdTCP15, further increasing the binding of MdWRKY53 to the MdPMEI45 promoter and inducing MdPMEI45 expression to prevent Al from crossing cell wall. MdWRKY53 also bound to the promoter of MdALS3 and enhanced its transcription to compartmentalize Al in vacuoles under AlCl3 stress. We therefore identified two modules involved in alleviating AlCl3 stress in woody plant apple: the SL-WRKY+TCP-PMEI module required for excluding external Al by blocking the entry of Al3+ into cells and the SL-WRKY-ALS module allowing internal detoxification of Al through vacuolar compartmentalization. These findings lay a foundation for the practical application of SLs in agriculture.

Endovascular thrombectomy for acute ischemic stroke in elderly patients with large ischemic cores.

BACKGROUND: Understanding the benefits and risks of endovascular therapy (EVT) is crucial for elderly patients with large ischemic cores, as the combination of advanced age and extensive brain infarction may negatively impact clinical outcomes. METHODS: The study retrospectively analyzed clinical outcomes for elderly stroke patients (age ≥ 70) with large ischemic cores (Alberta Stroke Program Early CT Score [ASPECTS] < 6 or ischemic cores ≥ 70 ml) in the anterior circulation using data from our prospective database between June 2018 and January 2022. The effectiveness and risks of EVT in those patients were investigated, with the primary outcome being fair outcome (modified Rankin Scale, mRS ≤ 3). RESULTS: Among 182 elderly patients with large ischemic core volume (120 in the EVT group and 62 in the non-EVT group), 20.9% (38/182, 22.5% in the EVT group vs. 17.7% in the non-EVT group) achieved a fair outcome. Meanwhile, 49.5% (90/182, 45.8% in the EVT group vs. 56.5% in the non-EVT group) of them died at 3 months. The benefits of EVT numerically exceeded non-EVT treatment for those aged ≤ ~ 85 years or with a mismatch volume ≥ ~ 50 ml. However, after adjustment, EVT was associated with an increased risk of symptomatic intracranial hemorrhage (aOR 4.24, 95%CI 1.262-14.247). CONCLUSIONS: This study highlights the clinical challenges faced by elderly patients with large infarctions, resulting in poor outcomes at 3 months. EVT may still provide some benefits in this population, but it also carries an increased risk of intracranial hemorrhage.

Short-term exposure to extreme temperature and outpatient visits for respiratory diseases among children in the northern city of China: a time-series study.

BACKGROUND: Although studies have indicated that extreme temperature is strongly associated with respiratory diseases, there is a dearth of studies focused on children, especially in China. We aimed to explore the association between extreme temperature and children's outpatient visits for respiratory diseases and seasonal modification effects in Harbin, China. METHODS: A distributed lag nonlinear model (DLNM) was used to explore the effect of extreme temperature on daily outpatient visits for respiratory diseases among children, as well as lag effects and seasonal modification effects. RESULTS: Extremely low temperatures were defined as the 1st percentile and 2.5th percentile of temperature. Extremely high temperatures were defined as the 97.5th percentile and 99th percentile of temperature. At extremely high temperatures, both 26 °C (97.5th) and 27 °C (99th) showed adverse effects at lag 0-6 days, with relative risks (RRs) of 1.34 [95% confidence interval (CI): 1.21-1.48] and 1.38 (95% CI: 1.24-1.53), respectively. However, at extremely low temperatures, both - 26 °C (1st) and - 23 °C (2.5th) showed protective effects on children's outpatient visits for respiratory diseases at lag 0-10 days, with RRs of 0.86 (95% CI: 0.76-0.97) and 0.85 (95% CI: 0.75-0.95), respectively. We also found seasonal modification effects, with the association being stronger in the warm season than in the cold season at extremely high temperatures. CONCLUSIONS: Our study indicated that extremely hot temperatures increase the risk of children's outpatient visits for respiratory diseases. Efforts to reduce the exposure of children to extremely high temperatures could potentially alleviate the burden of pediatric respiratory diseases, especially during the warm season.

Association between the prognostic nutritional index and severe headache or migraine: a population-based study.

PURPOSE: Migraine is a highly prevalent headache disorder, and intake of various nutrients and special diets may improve migraine symptoms. We aimed to clarify the association between nutritional status and migraine. PATIENTS AND METHODS: We collected the data of 1838/8953 (migraineurs/all participants) from the National Health and Nutrition Examination Survey (NHANES) 1999-2004 cycle. We used weighted multivariable linear or logistic regression analyses to study the association between the prognostic nutritional index (PNI) and the occurrence of severe headache or migraine. RESULTS: After adjusting for confounding variables, we found that mild (PNI 45-50) or moderate to severe (PNI <45) malnutrition were associated with higher prevalence of severe headache or migraine (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.00-1.12, P = 0.004; OR 1.07, 95% CI 1.03-1.12, P < 0.001). In addition, we found that those with severe headache or migraine consumed less alcohol, dietary fiber, cholesterol, total folate, vitamin A, riboflavin, vitamin B6, vitamin B12, vitamin C, vitamin K, selenium, potassium, magnesium, and copper, and consumed more caffeine and theobromine than did those without severe headache or migraine. CONCLUSION: The PNI is associated with migraine prevalence, and may thus serve as a predictor of migraine risk and highlights the potential of nutrition-based strategies for migraine prevention and treatment.

Assessing the influencing factors of out-of-pocket costs on tuberculosis in Sichuan Province: a cross-sectional study.

BACKGROUND: Although diagnosis and treatment services for tuberculosis (TB) are provided free of charge in most countries, direct non-medical and indirect costs due to absenteeism, also place a significant burden on patients and their families. Sichuan Province has the second highest incidence of TB in China, with an incidence of approximately 100 cases per 100 000 people. However, there are limited research on out-of-pocket expenditure (OOPE) and its influencing factors in TB patients in Sichuan Province. METHODS: A retrospective cross-sectional study was conducted on TB patients in designated medical institutions for TB in Sichuan Province from 2017-2021. A face-to-face questionnaire was conducted to obtain the information related to hospitalization of patients, and the multi-level regression model was used to analyse the factors that influence OOPE and total out-of-pocket expenditure (TOOPE) of TB patients. RESULTS: A total of 2644 patients were investigated, and 74.24% of TB patients and their families experienced catastrophic total costs due to TB. The median total cost was 9223.37 CNY (1429.98 USD), in which the median direct and indirect costs of TB patients were 10185.00 CNY (1579.07 USD) and 2400.00 CNY (372.09 USD), respectively, and indirect costs contributed to 43% of total costs. The median OOPE and TOOPE costs were 6024.00 CNY (933.95 USD) and 11890.50 CNY (1843.49 USD), respectively. OOPE and TOOPE had common influencing factors including whether the patient's family had four or more members, a history of hospitalization, combination with other types of TB, the number of visits before diagnosis, and co-occurrence with chronic disease. CONCLUSIONS: The OOPE and TOOPE for TB patients and their families in Sichuan Province are still heavy. In the long run, it is necessary to strengthen education and awareness campaigns on TB related knowledge, disseminate basic medical knowledge to the public, improve healthcare-seeking behavior, and enhance the healthcare infrastructure to improve the accuracy of TB diagnosis and reduce the significant OOPE and TOOPE faced by TB patients and their families in Sichuan Province.

Association between creatinine to body weight ratio and all-cause mortality: a cohort study of NHANES.

Research on the relationship between the weight-adjusted skeletal muscle mass index and all-cause mortality is rare, and even rarer is the relationship between the creatinine/body weight (Cre/BW) ratio and all-cause mortality. Therefore, this study aimed to investigate the relationship between the Cre/BW ratio and mortality in individuals with normal renal function. This prospective study used data from the National Health and Nutrition Examination Survey (NHANES) database. A Cox hazard model was used to analyze the relationship between the Cre/BW ratio and mortality risk. In total, 45,459 participants were included, of which 49.97% were women, with an average age of 45.68 ± 18.08 years. The incidence of all-cause mortality was 10.9% among these participants during the median (interquartile range) follow-up of 9.6 (5.2, 14.2) years. After adjusting for all covariates, a U-shaped relationship was found between the Cre/BW ratio and all-cause mortality (P for nonlinearity <0.001), with the lowest risk observed at Cre/BW ratios (×100) between 0.821 and 0.987. In the threshold effect analysis, the Cre/BW ratio (×100) had a threshold value of 0.96. When the Cre/BW ratio (×100) was <0.96, all-cause mortality was negatively associated with the Cre/BW ratio (×100) (0.63 (0.41, 0.97)). In contrast, when the Cre/BW ratio (×100) was ≥0.96, the higher Cre/BW ratio was associated with a greater hazard ratio of all-cause mortality (1.67 (1.41, 1.97)). In conclusion, we report a U-shaped relationship between the Cre/BW ratio and all-cause mortality. Controlling the Cre/BW ratio within a certain range may reduce the risk of all-cause mortality.

Association between human herpes simplex virus and periodontitis: results from the continuous National Health and Nutrition Examination Survey 2009-2014.

BACKGROUND: Periodontitis is a common chronic oral disease which seriously affects people's quality of life. Although human herpes simplex virus (HSV) is also found in periodontal lesions, the association between HSV infection and periodontitis is unclear. METHODS: The National Health and Nutrition Examination Survey (NHANES) data for 2009-2010, 2011-2012 and 2013-2014 was combined, and the association between HSV infection and periodontitis in the general population and particular subgroups was investigated through weighted multi-logistic analyses. RESULTS: There were 4,733 participants aged 30-50 years old with clinically assessed periodontitis concurrent with HSV infection. In general analysis, after adjusted for covariates, both HSV-1 (OR = 1.09, P < 0.001) and HSV-2 (OR = 1.06, P = 0.030) infection was significantly associated with periodontitis. In subgroup analyses, compared with patients without HSV infection, patients with HSV-1( +) & HSV-2( +) and HSV-1( +) & HSV-2(-) infection showed higher risk of periodontitis in all subgroups (OR = 1.15, OR = 1.09, P < 0.001), while patients with HSV-1(-) & HSV-2( +) infection showed higher risk of and periodontitis only in the subgroup of people aged 40-50 years (OR = 1.10, P = 0.032) and the Mexican-American subgroup (OR = 1.35, P = 0.042). When only severe periodontitis is considered, HSV infection was associated with periodontitis, no matter the patient was infected with either of the virus or both. CONCLUSIONS: HSV-1 infection was significantly associated with periodontitis and severe periodontitis, while HSV-2 infection was associated with severe periodontitis, and periodontitis in 40-50-year-olds and Mexican-Americans.

Association between niacin and mortality among patients with cancer in the NHANES retrospective cohort.

BACKGROUND: The vitamin niacin is used as a lipid-regulating supplement, but it is unknown whether niacin has a positive influence on cancer prognosis. In this study, we examine the relationship between niacin intake and mortality among patients with cancer. METHODS: Our study utilized all available continuous data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014. Multivariable Cox regression models were applied in order to investigate dietary niacin intake's association with mortality. We compared the survival probability between groups of low and high niacin intake by plotting Kaplan-Meier curves. An analysis of subgroups was used to investigate heterogeneity sources. RESULTS: A total of 3504 participants were included in the cohort, with 1054 deaths. One thousand eight hundred forty-seven participants (52.3%) were female, 2548 participants (73.4%) were white, and the mean age (SE) was 65.38 years (0.32). According to multivariate logistic regression analysis, niacin intake was negatively associated with mortality outcomes in patients with cancer, with P values below 0.05 in all models. In subgroup analyses based on sex, age, and BMI, the association persisted. The Kaplan-Meier curves indicate that high niacin intake groups have better survival rates than low intake groups. Niacin supplementation improved cancer mortality but not all-cause mortality. CONCLUSION: According to our study, higher dietary niacin intake was associated with lower mortality in cancer patients. Niacin supplements improved cancer survival rates, but not all causes of mortality.

Long-term exposure to ambient air pollution and greenness in relation to pulmonary tuberculosis in China: A nationwide modelling study.

Previous studies have attempted to clarify the relationship between the occurrence of pulmonary tuberculosis (PTB) and exposure to air pollutants. However, evidence from multi-centres, particularly at the national level, is scarce, and no study has examined the modifying effect of greenness on air pollution-TB associations. In this study, we examined the association between long-term exposure to ambient air pollutants (PM10 p.m.2.5, and O3) and monthly PTB or smear-positive pulmonary tuberculosis (SPPTB) incidence to further evaluate whether these associations were affected by greenness in mainland China using a two-stage analytic procedure. PM2.5 was positively associated with both PTB and SPPTB incidence, with relative risk (RR) of 1.12 (95% confidence interval [CI]: 1.03, 1.22) and 1.08 (95% CI: 1.02, 1.10) per 10 µg/m3 increase, respectively. Furthermore, PM10 was positively associated with PTB incidence, with RR of 1.07 (95% CI: 1.01, 1.13). However, O3 was not associated with the monthly incidence of PTB or SPPTB. The normalized difference vegetation index (NDVI) exhibited a modifying effect on the association between PM2.5 exposure and SPPTB incidence in northern areas, with RR of 1.16 (95% CI: 1.03, 1.31) in lower mean annual NDVI areas than in the higher areas (RR = 0.98, 95% CI: 0.87, 1.09). This nationwide analysis indicated that NDVI could reduce the effect of air pollutants on TB incidence particularly in the northern areas. Long-term exposure to particulate matter (PM) may increase the occurrence of PTB or SPPTB in China, and further studies involving larger numbers of SPPTB cases are required to confirm the effects of PM exposure on SPPTB incidence in the future.

Low dose statins improve prognosis of ischemic stroke patients with intravenous thrombolysis.

BACKGROUND: For acute ischaemic stroke patients, it is uncertain whether intravenous thrombolysis combined with statins might increase the therapeutic effect. Additionally, using high-intensity statins after thrombolysis may increase the risk of bleeding in patients. Asian stroke patients often take low-dose statins. It is speculated that reducing the dose of statins may improve the risk of bleeding. METHODS: Data from consecutive acute ischaemic stroke patients with intravenous thrombolysis were prospectively collected. Efficacy outcomes included NIHSS (National Institutes of Health Stroke Scale) score improvement at 7 days after admission and mRS (Modified Rankin Scale) improvement at 90 days. Safety outcomes included haemorrhage events (intracerebral haemorrhage and gastrointestinal haemorrhage) in the hospital and death events within 2 years. RESULTS: The study finally included 215 patients. The statin group had a higher percentage of NIHSS improvement at 7 days (p < 0.001) and a higher percentage of a favourable functional outcome (FFO, mRS < = 2) (p < 0.001) at 90 days. The statin group had a lower percentage of intracerebral haemorrhage (p < 0.001) and gastrointestinal haemorrhage (p = 0.003) in the hospital and a lower percentage of death events (p < 0.001) within 2 years. Logistic regression indicated that statin use was significantly related to NIHSS improvement (OR = 4.697, p < 0.001), a lower percentage of intracerebral haemorrhage (OR = 0.372, p = 0.049) and gastrointestinal haemorrhage (OR = 0.023, p = 0.016), and a lower percentage of death events (OR = 0.072, p < 0.001). CONCLUSION: For acute ischaemic stroke patients after intravenous thrombolysis, the use of low-dose statins was related to NIHSS improvement at 7 days and inversely related to haemorrhage events in the hospital and death events within 2 years, especially for moderate stroke or noncardioembolic stroke patients.

Development and external validation of a nomogram for neurosyphilis diagnosis among non-HIV patients: a cross-sectional study.

BACKGROUND: The diagnosis of neurosyphilis is challenging due to the requirement of a lumbar puncture and cerebrospinal fluid (CSF) laboratory tests. Therefore, a convenient diagnostic nomogram for neurosyphilis is warranted. This study aimed to construct diagnostic models for diagnosing neurosyphilis. METHODS: This cross-sectional study included data of two patient cohorts from Western China Hospital of Sichuan University between September 2015 and April 2021 and Shangjin Hospital between September 2019 and April 2021 as the development cohort and the external validation cohort, respectively. A diagnostic model using logistic regression analysis was constructed to readily provide the probability of diagnosis at point of care and presented as a nomogram. The clinical usefulness of the diagnostic models was assessed using a receiver operating characteristic (ROC) and Harrell concordance (Harrell C) index for discrimination and calibration plots for accuracy, which adopted bootstrap resampling 500 times. RESULTS: One hundred forty-eight and 67 patients were included in the development and validation cohorts, respectively. Of those, 131 were diagnosed as having reactive neurosyphilis under the criteria of positive results in both CSF treponemal and non-treponemal tests. In the development cohort, male, psychiatric behaviour disorders, and serum toluidine red unheated serum test were selected as diagnostic indicators applying a stepwise procedure in multivariable logistic model. The model reached 80% specificity, 79% sensitivity, and 0·85 area under the curves (AUC) (95% confidence interval, 0·76-0·91). In the validation cohorts, the Harrell C index for the diagnostic possibility of reactive neurosyphilis was 0·71. CONCLUSIONS: A convenient model using gender, presence of psychiatric behaviour disorders, and serum TRUST titre was developed and validated to indicate diagnostic results in patients suspected of neurosyphilis. Checking the model value of factors on nomogram is a feasible way to assist clinicians and primary health servers in updating patients' medical charts and making a quantitatively informed decision on neurosyphilis diagnosis. TRIAL REGISTRATION: This research was retrospectively registered in the Ethics committee on biomedical research, West China Hospital of Sichuan University. The research registration and committee's reference number was 1163 in 2020 approval.

Bisphosphonates and risk of cancers: a systematic review and meta-analysis.

BACKGROUND: It is unclear whether bisphosphonates are associated with risk of cancers. Therefore, this meta-analysis aimed to evaluate the effect of bisphosphonates on overall cancers. METHODS: A search in Pubmed, Embase, Cochrane Library and Web of Science databases was conducted, from the inception date of each resource to September 26, 2019. The summarised effect estimates with 95% CIs were calculated using a random-effect model. Heterogeneity and publication bias were explored. RESULTS: Thirty-four articles were included in this study (4,508,261 participants; 403,196 cases). The results revealed that bisphosphonates significantly decreased the risk of colorectal cancer (RR = 0.89, 95% CI: 0.81-0.98), breast cancer (RR = 0.87, 95% CI: 0.82-0.93) and endometrial cancer (RR = 0.75, 95% CI: 0.61-0.94), but no significant association was observed in all-cause cancer. Furthermore, nitrogen-containing bisphosphonates only had protective effects both on breast cancer (RR = 0.94, 95% CI: 0.90-0.99) and endometrial cancer (RR = 0.70, 95% CI: 0.54-0.92). Non-nitrogen-containing bisphosphonates tended to increase the risk of liver cancer (RR = 2.14, 95% CI: 1.23-3.72) and pancreas cancer (RR = 1.75, 95% CI: 1.32-2.33). CONCLUSION: Bisphosphonates are significantly associated with risk reduction of colorectal, breast and endometrial cancer, especially nitrogen-containing bisphosphonates. It should be noted that non-nitrogen-containing bisphosphonates might increase the risk of liver and pancreas cancer. Large prospective cohort studies are needed to find the causal association between bisphosphonates and risk of cancers.

Epidemiology of physical activity-related injuries in Chinese university students.

Knowledge gaps of the physical activity-related injury (PARI) problem among general undergraduates exist. We conducted a study in four universities, where 1421 students graded 1-3 were interviewed face-to-face during April and May after their completion of the baseline survey in March and April 2017, aiming to describe the incidence and characteristics of PARI. PARI experience and physical activity (PA) participation in the past 12 months were collected. Injury incidence density (IID) and risk, and injury characteristics were evaluated for the overall sample and by gender. Pearson chi-square or Fisher's exact tests and independent-sample t tests were used to test between-group differences. We found that 486 PARIs were reported totally by 289 participants, with an overall IID of 0.57 per 1000 hours of exposure (males: 1.07, females: 0.45) and an injury risk of 0.34 injuries/student/y (males: 0.52; females: 0.28). Higher IIDs were found in roller skating, football, and basketball. The majority of injuries occurred outdoors and involved the lower extremities, with sprain and strain being the primary injury types. Moreover, most injuries were new, acute, and happened in non-contact situations. Of all injuries, 52.1% required medical attention and 64.6% resulted in inactivity of one or more days. Some significant differences were observed between males and females. Our study indicates that PARI is a public health concern among Chinese university students, which can provide direction for targeted prophylactic interventions to underpin the sex-specific injury mechanism to reduce PARI.

Genome-wide expression profiling analysis to identify key genes in the anti-HIV mechanism of CD4+ and CD8+ T cells.

Comprehensive bioinformatics analyses were performed to explore the key biomarkers in response to HIV infection of CD4+ and CD8+ T cells. The numbers of CD4+ and CD8+ T cells of HIV infected individuals were analyzed and the GEO database (GSE6740) was screened for differentially expressed genes (DEGs) in HIV infected CD4+ and CD8+ T cells. Gene Ontology enrichment, KEGG pathway analyses, and protein-protein interaction (PPI) network were performed to identify the key pathway and core proteins in anti-HIV virus process of CD4+ and CD8+ T cells. Finally, we analyzed the expressions of key proteins in HIV-infected T cells (GSE6740 dataset) and peripheral blood mononuclear cells(PBMCs) (GSE511 dataset). 1) CD4+ T cells counts and ratio of CD4+ /CD8+ T cells decreased while CD8+ T cells counts increased in HIV positive individuals; 2) 517 DEGs were found in HIV infected CD4+ and CD8+ T cells at acute and chronic stage with the criterial of P-value <0.05 and fold change (FC) ≥2; 3) In acute HIV infection, type 1 interferon (IFN-1) pathway might played a critical role in response to HIV infection of T cells. The main biological processes of the DEGs were response to virus and defense response to virus. At chronic stage, ISG15 protein, in conjunction with IFN-1 pathway might play key roles in anti-HIV responses of CD4+ T cells; and 4) The expression of ISG15 increased in both T cells and PBMCs after HIV infection. Gene expression profile of CD4+ and CD8+ T cells changed significantly in HIV infection, in which ISG15 gene may play a central role in activating the natural antiviral process of immune cells.

The similar to RCD-one 1 protein SRO1 interacts with GPX3 and functions in plant tolerance of mercury stress.

Heavy metals in the environment are one of the major limiting factors affecting plant growth and development. However, the mechanisms of the heavy metal-induced physiological processes remain to be fully dissected. Here, we explored that SRO1 can physically interact with Glutathione Peroxidase 3 (GPX3) in Arabidopsis. Under Hg treatment, similar to the sro1, the growth of the gpx3/sro1 was repressed more seriously and the number of true leaves was more reduced and etiolated than that of the wild type and gpx3 plants. The electrolyte leakage rates showed that cell membrane integrity in gpx3/sro1 was damaged more severely than in the wild type and gpx3 mutant. The Real-time PCR results have shown that the expression of the APX1 and CAT3 was reduced under mercury stress in the sro1 and sro1/gpx3. Our results suggested that the combination of the SRO1 and GPX3 may be contributed to plant response to mercury stress by regulating ROS intracellular oxidative homeostasis.

A Receptor-Like Kinase Mediates Ammonium Homeostasis and Is Important for the Polar Growth of Root Hairs in Arabidopsis.

Ammonium (NH4+) is both a necessary nutrient and an important signal in plants, but can be toxic in excess. Ammonium sensing and regulatory mechanisms in plant cells have not been fully elucidated. To decipher the complex network of NH4+ signaling, we analyzed [Ca2+]cyt-associated protein kinase (CAP) genes, which encode signaling components that undergo marked changes in transcription levels in response to various stressors. We demonstrated that CAP1, a tonoplast-localized receptor-like kinase, regulates root hair tip growth by maintaining cytoplasmic Ca2+ gradients. A CAP1 knockout mutant (cap1-1) produced elevated levels of cytoplasmic NH4+. Furthermore, root hair growth of cap1-1 was inhibited on Murashige and Skoog medium, but NH4+ depletion reestablished the Ca2+ gradient necessary for normal growth. The lower net NH4+ influx across the vacuolar membrane and relatively alkaline cytosolic pH of cap1-1 root hairs implied that mutation of CAP1 increased NH4+ accumulation in the cytoplasm. Furthermore, CAP1 functionally complemented the npr1 (nitrogen permease reactivator protein) kinase yeast mutant, which is defective in high-affinity NH4+ uptake via MEP2 (methylammonium permease 2), distinguishing CAP1 as a cytosolic modulator of NH4+ levels that participates in NH4+ homeostasis-regulated root hair growth by modulating tip-focused cytoplasmic Ca2+ gradients.

Glutathione homeostasis and Cd tolerance in the Arabidopsis sultr1;1-sultr1;2 double mutant with limiting sulfate supply.

KEY MESSAGE: Cadmium sensitivity in sultr1;1 - sultr1;2 double mutant with limiting sulfate supply is attributed to the decreased glutathione content that affected oxidative defense but not phytochelatins' synthesis. In plants, glutathione (GSH) homeostasis plays pivotal role in cadmium (Cd) detoxification. GSH is synthesized by sulfur (S) assimilation pathway. Many studies have tried to investigate the role of GSH homeostasis on Cd tolerance using mutants; however, most of them have focused on the last few steps of S assimilation. Until now, mutant evidence that explored the relationship between GSH homeostasis on Cd tolerance and S absorption is rare. To further reveal the role of GSH homeostasis on Cd stress, the wild-type and a sultr1;1-sultr1;2 double mutant which had a defect in two distinct high-affinity sulfate transporters were used in this study. Growth parameters, biochemical or zymological indexes and S assimilation-related genes' expression were compared between the mutant and wild-type Arabidopsis plants. It was found that the mutations of SULTR1;1 and SULTR1;2 did not affect Cd accumulation. Compared to the wild-type, the double mutant was more sensitive to Cd under limited sulfate supply and suffered from stronger oxidative damage. More importantly, under the same condition, lower capacity of S assimilation resulted in decreased GSH content in mutant. Faced to the limited GSH accumulation, mutant seedlings consumed a large majority of GSH in pool for the synthesis of phytochelatins rather than participating in the antioxidative defense. Therefore, homeostasis of GSH, imbalance between antioxidative defense and severe oxidative damage led to hypersensitivity of double mutant to Cd under limited sulfate supply.

Proteomic analysis of halotolerant proteins under high and low salt stress in Dunaliella salina using two-dimensional differential in-gel electrophoresis.

Dunaliella salina, a single-celled marine alga with extreme salt tolerance, is an important model organism for studying fundamental extremophile survival mechanisms and their potential practical applications. In this study, two-dimensional differential in-gel electrophoresis (2D-DIGE) was used to investigate the expression of halotolerant proteins under high (3 M NaCl) and low (0.75 M NaCl) salt concentrations. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and bioinformatics were used to identify and characterize the differences among proteins. 2D-DIGE analysis revealed 141 protein spots that were significantly differentially expressed between the two salinities. Twenty-four differentially expressed protein spots were successfully identified by MALDI-TOF/TOF MS, including proteins in the following important categories: molecular chaperones, proteins involved in photosynthesis, proteins involved in respiration and proteins involved in amino acid synthesis. Expression levels of these proteins changed in response to the stress conditions, which suggests that they may be involved in the maintenance of intracellular osmotic pressure, cellular stress responses, physiological changes in metabolism, continuation of photosynthetic activity and other aspects of salt stress. The findings of this study enhance our understanding of the function and mechanisms of various proteins in salt stress.

Analysis of methylated patterns and quality-related genes in tobacco (Nicotiana tabacum) cultivars.

Methylation-sensitive amplified polymorphism was used in this study to investigate epigenetic information of four tobacco cultivars: Yunyan 85, NC89, K326, and Yunyan 87. The DNA fragments with methylated information were cloned by reamplified PCR and sequenced. The results of Blast alignments showed that the genes with methylation information included chitinase, nitrate reductase, chloroplast DNA, mitochondrial DNA, ornithine decarboxylase, ribulose carboxylase, and promoter sequences. Homologous comparison in three cloned gene sequences (nitrate reductase, ornithine decarboxylase, and ribulose decarboxylase) indicated that geographic factors had significant influence on the whole genome methylation. Introns also contained different information in different tobacco cultivars. These findings suggest that synthetic mechanisms for tobacco aromatic components could be affected by different environmental factors leading to variation of noncoding regions in the genome, which finally results in different fragrance and taste in different tobacco cultivars.

Antifungal bromophenols from marine red alga Symphyocladia latiuscula.

Three new highly brominated polyphenols, 1-3, together with one known bromophenol, 4, were isolated from the EtOH extract of a marine red alga Symphyocladia latiuscula collected from the coast of Qingdao, P. R. China. Their structures were identified by extensive spectroscopic experiments (NMR and MS) and comparison with literature data. Compounds 3 and 4 showed activities against the Candida albicans with the MIC values of 25 and 12.5 µg/ml, respectively.