Three OsMYB36 members redundantly regulate Casparian strip formation at the root endodermis.

Plants have evolved a lignin-based Casparian strip (CS) in roots that restricts passive diffusion of mineral elements from the soil to the stele. However, the molecular mechanisms underlying CS formation in rice (Oryza sativa), which contains a CS at both the exodermis and endodermis, are poorly understood. Here, we demonstrate that CS formation at the rice endodermis is redundantly regulated by three MYELOBLASTOSIS (MYB) transcription factors, OsMYB36a, OsMYB36b, and OsMYB36c, that are highly expressed in root tips. Knockout of all three genes resulted in a complete absence of CS at the endodermis and retarded plant growth in hydroponic conditions and in soil. Compared with the wild-type, the triple mutants showed higher calcium (Ca) levels and lower Mn, Fe, Zn, Cu, and Cd levels in shoots. High Ca supply further inhibited mutant growth and increased Ca levels in shoots. Transcriptome analysis identified 1,093 downstream genes regulated by OsMYB36a/b/c, including the key CS formation gene OsCASP1 and other genes that function in CS formation at the endodermis. Three OsMYB36s regulate OsCASP1 and OsESB1 expression by directly binding to MYB-binding motifs in their promoters. Our findings thus provide important insights into the mechanism of CS formation at the endodermis and the selective uptake of mineral elements in roots.

A NAC transcription factor OsNAC3 positively regulates ABA response and salt tolerance in rice.

BACKGROUND: NAC (NAM, ATAF and CUC) transcription factors (TFs) play vital roles in plant development and abiotic stress tolerance. Salt stress is one of the most limiting factors for rice growth and production. However, the mechanism underlying salt tolerance in rice is still poorly understood. RESULTS: In this study, we functionally characterized a rice NAC TF OsNAC3 for its involvement in ABA response and salt tolerance. ABA and NaCl treatment induced OsNAC3 expression in roots. Immunostaining showed that OsNAC3 was localized in all root cells. OsNAC3 knockout decreased rice plants' sensitivity to ABA but increased salt stress sensitivity, while OsNAC3 overexpression showed an opposite effect. Loss of OsNAC3 also induced Na+ accumulation in the shoots. Furthermore, qRT-PCR and transcriptomic analysis were performed to identify the key OsNAC3 regulated genes related to ABA response and salt tolerance, such as OsHKT1;4, OsHKT1;5, OsLEA3-1, OsPM-1, OsPP2C68, and OsRAB-21. CONCLUSIONS: This study shows that rice OsNAC3 is an important regulatory factor in ABA signal response and salt tolerance.

The tonoplast-localized transporter OsABCC9 is involved in cadmium tolerance and accumulation in rice.

Cadmium (Cd) is a highly toxic element to living organisms, and its accumulation in the edible portions of crops poses a potential threat for human health. The molecular mechanisms underlying Cd detoxification and accumulation are not fully understood in plants. In this study, the involvement of a C-type ABC transporter, OsABCC9, in Cd tolerance and accumulation in rice was investigated. The expression of OsABCC9 was rapidly induced by Cd treatment in a concentration-dependent manner in the root. The transporter, localized on the tonoplast, was mainly expressed in the root stele under Cd stress. OsABCC9 knockout mutants were more sensitive to Cd and accumulated more Cd in both the root and shoot compared to the wild-type. Moreover, the Cd concentrations in the xylem sap and grain were also significantly increased in the knockout lines, suggesting that more Cd was distributed from root to shoot and grain in the mutants. Heterologous expression of OsABCC9 in yeast enhanced Cd tolerance along with an increase of intracellular Cd content. Taken together, these results indicated that OsABCC9 mediates Cd tolerance and accumulation through sequestration of Cd into the root vacuoles in rice.

The phytoestrogen glabrene prevents osteoporosis in ovariectomized rats through upregulation of the canonical Wnt/ß-catenin signaling pathway.

This study systematically investigated the effects of phytoestrogen glabrene on postmenopausal osteoporosis in an ovariectomy (OVX) rat model. Glabrene administration (25, 50, and 100 mg/kg) for 13 weeks can significantly slow down the body weight gain and slightly increase the uterus weight of OVX rats. The increased levels of U-Ca, U-P levels, urine DPD/creatinine, serum ALP, OCN, triglycerides, and total cholesterol induced by OVX were dramatically inhibited in rats, whereas no difference occurred for S-Ca and S-P in all groups. Furthermore, glabrene can enhance bone mineral density of the right femur, fourth-lumbar vertebra and tibia and improve biomechanical parameters, such as femoral neck loading force, three-point bending of the tibia, and vertebral compression in OVX rats. Moreover, glabrene greatly suppressed the expression of TRAP protein but increased OPG and BGP protein expression in tibia tissue of OVX rats. In addition, OVX-induced reduction of Lrp-5, ß-catenin, Runx2, and Osx protein expression was all restored by glabrene treatment. The present study indicated that glabrene might be a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis via activation of the Wnt/ß-catenin signaling pathway.

[Epidemiological survey of the association between non alcoholic fatty liver disease and metabolic syndrome in civil servants of Chongqing city].

OBJECTIVE: To investigate the association between non alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS). METHODS: A cross-sectional multiple-stage stratified survey was performed. A total of 2190 civil servants of Chongqing city were invited to participate in the survey covering physical examination, serum biochemistry-profile and ultrasonographic examination of liver. RESULTS: Of 2176 valid questionnaires, altogether 455 cases were diagnosed as NAFLD and 231 individuals were diagnosed as MS. The prevalence of obesity, hyperglycemia, blood lipid disturbance, primary hypertension, NAFLD and MS was 38.3%, 5.5%, 31.7%, 29.9%, 20.9% and 10.6% respectively, which was increased along with aging (chi2 = 31.775, P = 0.000; chi2 = 25.985, P = 0.000; chi2 = 44.818, P = 0.000; chi2 =149.802, P = 0.000; chi2 = 61.302, P = 0.000; chi2 = 43.508, P = 0.000 a partly). The prevalence of obesity, hyperglycemia, dyslipidemia, primary hypertension, metabolic syndrome was significantly higher than those in control group (chi2 = 384.554, P = 0.000; chi2 = 25.597, P = 0.000; chi2 = 370.849, P = 0.000; chi2 = 40.252, P = 0.000; chi2 = 215.077, P = 0.000 separately), and the level of body mass index (BMI), fasting plasma glucose (FPG), triglyceride (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP) in NAFLD group was remarkably higher than those in control group (t = 26.308, P = 0.000; t = 6.055, P = 0.000; t = 15.980, P = 0.000; t = 10.550, P = 0.000; t = 13.628, P = 0.000 respectively), while the level of high-density lipoprotein cholesterol (HDL-C) was on the opposite (t = 20.067, P = 0.000). Compared with the control group, odds risk for NAFLD was 22.82 folds (95% CI: 12.64-41.19) in obesity, 20.97 folds (95% CI: 11.21-39.24) in hyperglycemia, 24.40 folds (95% CI: 13.51-44.07) in dyslipidemia, 15.73 folds (95% CI: 8.66-28.60) in primary hypertension, while the risk for NAFLD was the highest in MS (OR = 31.06, 95% CI: 17.12-56.35). There were simple or multiple metabolic disorders in 455 individuals diagnosed as NAFLD, and 21 case (4.6%) with obesity, hyperglycemia, dyslipidemia and primary hypertension. CONCLUSION: NAFLD is closely related with MS, which may be considered as a feature of MS.

[Study on the change of myocardial cell and matrix in the rats with insulin resistance and type 2 diabetes mellitus].

OBJECTIVE: To explore the injury of insulin resistance on cardiac muscle cell and matrix, and the relationship between insulin resistance and diabetic cardiomyopathy. METHODS: Twenty four Wistar rats of 6 months were randomly divided into normal control (N), insulin resistance group (I), diabetic group (D). Euglycemic insulin clamp technique (EICT) was used to determine insulin resistance (IR). Cadiocyte apoptosis was evaluated by TUNEL. Heart weight (HW) and body weight (BW) were measured to calculate HW/BW. Ultra-microstructure of cardiac muscle cell and structure of heart was observed. Masson dyeing, hydroxyproline detection and immunohistochemistry were used to measure the levels of collagen protein. RESULTS: Compared with controls, GIR decreased remarkably in D group and I group (P < 0.01). The number of apoptosis cell in I group was lower than that of D group (P < 0.01), and higher than that of N group (P < 0.01). Injury change of ultramicrostructure of myocardial cell was observed in the rats with type 2 diabetes mellitus or insulin resistance. Interstitial fibrosis of heart occurred in D group and I group. Content of Hydroxyproline, the level of I , III type of collagen, and the total level of collagen in I group were lower than those in D group, and higher than those in N group (P < 0.05). CONCLUSION: Insulin resistance in the rats with type 2 diabetes mellitus or insulin resistance can injury myocardial cell and matrix.