[Effects of Different Exogenous Selenium Species Application on Growth and Cadmium Uptake of Pak Choi in Cadmium Contaminated Soil].

This study explored the discrepancy in the detoxification effects of different exogenous selenium (Se) species in cadmium (Cd)-contaminated soil to provide a scientific basis for the control of Cd pollution in the soil and the safe production of crops. A pot experiment was conducted to compare the effects of different concentrations (0, 0.5, 1.0, and 2.5 mg·kg-1) of selenite and selenate on the growth (root length, shoot height, biomass, and photosynthetic parameters), uptake, and translocation of Cd on pak choi in Cd-contaminated soil. The results indicated that the detoxification effect of a low Se concentration (≤1.0 mg·kg-1) treatment on Cd was better than that with a high Se concentration (2.5 mg·kg-1) treatment, and the selenite treatment demonstrated a greater detoxification effect on Cd than the corresponding selenate treatment. Meanwhile, the application of low-concentration selenite and selenate both increased the SPAD value, Pn, Gs, Ci, biomass, and shoot length of the pak choi, and the 1.0 mg·kg-1 selenite treatment had the most significant (P<0.05) effect (except Ci). Nevertheless, the photosynthetic parameters of the pak choi under the high-concentration Se were significantly lower than those under the low Se concentration treatment (except Tr, P<0.05). Compared with the treatment without Se (control), the uptake of Cd in the pak choi was reduced under different Se treatments. Compared with the control, the Cd concentration in the shoots of the pak choi treated with 1.0 mg·kg-1 of selenite and selenate decreased by 40.0% and 20.5% (P<0.05), respectively. In addition, the translocation of Cd from the root to the shoot was significantly reduced under the 0.5 mg·kg-1 selenate treatment, while the high-concentration treatments of either exogenous Se promoted the translocation of Cd. Overall, applying the appropriate amount of exogenous Se could promote the photosynthesis and biomass of pak choi, and reduce the accumulation of Cd in pak choi. Therefore, the 1.0 mg·kg-1 selenite treatment is recommended for the control and safe utilization of Cd in Cd-contaminated soil.

The associations of TNF-α gene polymorphisms with bone mineral density and risk of osteoporosis: A meta-analysis.

OBJECTIVE: Fracture is a common consequence of osteoporosis and is associated with high morbidity and mortality. Recently, increasing evidence has suggested that polymorphisms in tumor necrosis factor-α (TNF-α) gene were associated with osteoporosis risk and bone mineral density (BMD), but results remain conflicting. We herein performed a meta-analysis based on evidence currently available from the literature to make a more precise estimation of these relationships. METHODS: The PubMed, EMBASE, Cochrane Library, CNKI (China National Knowledge Infrastructure) and Wan Fang databases were searched for eligible studies. Articles meeting the inclusion criteria were comprehensively reviewed and all available data were accumulated. The pooled odds ratios (ORs) or mean differences (MDs) and corresponding 95% confidence intervals (CIs) were applied to assess the strength of the relationships. RESULTS: A total of 15 studies involving 5273 subjects were included in our meta-analysis. The GG genotype of TNF-α G308A was associated with an increased risk of osteoporosis under a mutant model (GG vs GA+AA: OR = 0.63, 95% CI: 0.51-0.77, P < 0.0001, I2  = 31%). Additionally, we also observed a significant association between G308A polymorphism and BMD of lumbar spine (AA vs GG: P = 0.01, I2  = 53%). However, TNF-α T1031C, C857T and C863A polymorphisms had no obvious impacts on osteoporosis risk. CONCLUSIONS: The present meta-analysis demonstrated that TNF-α G308A polymorphism may act as a potential candidate biomarker for screening, diagnosis, and treatment of osteoporosis, which will help improve individualized therapy of osteoporosis patients in clinics.

Mitochondrial DNA polymorphisms in Phytophthora infestans: new haplotypes are identified and re-defined by PCR.

Polymorphisms of mitochondrial DNA (mt-DNA) are particularly useful for monitoring specific pathogen populations like Phytophthora infestans. Basically type I and II of P. infestans mt-DNA were categorized by means of polymorphism lengths caused by an ~2 kb insertion, which can be detected via restriction enzyme digestion. In addition genome sequencing of haplotype Ib has been used as a simple Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method to indirectly identify type I and II alterations through EcoR I restriction enzyme DNA fragment patterns of the genomic P4 area. However, with the common method, wrong mt-DNA typing occurs due to an EcoR I recognition site mutation in the P4 genomic area. Genome sequencing of the four haplotypes (Ia, Ib, IIa, and IIb) allowed us to thoroughly examine mt-DNA polymorphisms and we indentified two hypervariable regions (HVRs) named HVRi and HVRii. The HVRi length polymorphism caused by a 2 kb insertion/deletion was utilized to identify mt-DNA types I and II, while another length polymorphism in the HVRii region is caused by a variable number of tandem repeats (n = 1, 2, or 3) of a 36 bp sized DNA stretch and was further used to determine mt-DNA sub-types, which were described as R(n = 1, 2, or 3). Finally, the P. infestans mt-DNA haplotypes were re-defined as IR(1) or IIR(2) according to PCR derived HVRi and HVRii length polymorphisms. Twenty-three isolates were chosen to verify the feasibility of our new approach for identifying mt-DNA haplotypes and a total of five haplotypes (IR(1), IR(2), IR(3), IIR(2) and IIR(3)) were identified. Additionally, we found that six isolates determined as type I by our method were mistakenly identified as type II by the PCR-RFLP technique. In conclusion, we propose a simple and rapid PCR method for identification of mt-DNA haplotypes based on sequence analyses of the mitochondrial P. infestans genome.