New Insights into Selenium Enrichment in the Soil of Northwestern Guizhou, Southwest China.

Selenium (Se) is an essential trace element for animals and plants. Se in soil has an important influence on the Se intake by animals and plants. To explore the source of Se in soils of the zinc-smelting area in northwest Guizhou, China, 271 topsoils and 50 deep soil samples were collected, and the concentration, speciation and distribution of Se in soils were analysed. The results showed that the concentration of Se in topsoils ranged from 0.2 mg/kg to 1.79 mg/kg, with an average of 0.84 mg/kg, which was more than 2 times of that in deep soil. These observations indicated that Se was enriched in the surface layer of soil. In terms of spatial distribution, high-Se topsoils (> 1.0 mg/kg) were mainly distributed near the zinc smelting area, and topsoil samples with relatively low content of Se were mainly distributed in areas with less human activities influence. The Se occurrence species in topsoils were in the order of residue, organic-binding, humic-acid binding, water-soluble, Fe/Mn/Al oxide-binding, carbonate-binding and ion-exchange. The contribution of residual Se to total Se in topsoil was decisive, and the content of other species of selenium changed slightly. The Se speciation that was residual in soil is difficult for plants to utilize, which is consistent with previous studies on seleniferous soils caused by zinc smelting. These results indicated that the main reason for Se enrichment in the topsoils of northwest Guizhou Province was indigenous zinc smelting.

Root exudates drive interspecific facilitation by enhancing nodulation and N2 fixation.

Plant diversity in experimental systems often enhances ecosystem productivity, but the mechanisms causing this overyielding are only partly understood. Intercropping faba beans (Vicia faba L.) and maize (Zea mays L.) result in overyielding and also, enhanced nodulation by faba beans. By using permeable and impermeable root barriers in a 2-y field experiment, we show that root-root interactions between faba bean and maize significantly increase both nodulation and symbiotic N2 fixation in intercropped faba bean. Furthermore, root exudates from maize promote faba bean nodulation, whereas root exudates from wheat and barley do not. Thus, a decline of soil nitrate concentrations caused by intercropped cereals is not the sole mechanism for maize promoting faba bean nodulation. Intercropped maize also caused a twofold increase in exudation of flavonoids (signaling compounds for rhizobia) in the systems. Roots of faba bean treated with maize root exudates exhibited an immediate 11-fold increase in the expression of chalcone-flavanone isomerase (involved in flavonoid synthesis) gene together with a significantly increased expression of genes mediating nodulation and auxin response. After 35 d, faba beans treated with maize root exudate continued to show up-regulation of key nodulation genes, such as early nodulin 93 (ENOD93), and promoted nitrogen fixation. Our results reveal a mechanism for how intercropped maize promotes nitrogen fixation of faba bean, where maize root exudates promote flavonoid synthesis in faba bean, increase nodulation, and stimulate nitrogen fixation after enhanced gene expression. These results indicate facilitative root-root interactions and provide a mechanism for a positive relationship between species diversity and ecosystem productivity.

Cytochrome P450 2AA molecular clone, expression pattern, and different regulation by fish oil and lard oil in diets of grass carp (Ctenopharyngodon idella).

Cytochrome P450 enzymes (CYP enzymes) catalyze important metabolic reactions of exogenous and endogenous substrates, including fatty acid. In this study, we cloned the complete CDS of the cytochrome P450 2AA (CYP2AA) gene from the grass carp (Ctenopharyngodon idella) for the first time. CYP2AA consisted of 1500 bp, which encoded a predicted protein of 499 amino acids. The identities of CYP2AA between C. idella and zebrafish were 86%. It consists of the conserved heme-binding motif FXXGXXXCXG. Quantitative real-time PCR analysis indicated that CYP2AA mRNA in C. idella was highly expressed in liver and adipose tissue. The effects of fish oil and lard oil in diets on expression of CYP2AA mRNA in vivo were also investigated. The fish oil (FO) group exhibited significantly higher CYP2AA expression in adipose tissue than the lard oil (LO) group (P < 0.01), whereas the mRNA expression of CYP2AA was not notably different in liver. It suggested that the high abundance of CYP2AA mRNA expression in adipose tissue could be induced by fish oil. Our findings provided molecular characterization and expression profile of CYP2AA, and enhanced our understanding of CYP2AA in fish lipid metabolism.

[Karst Hydrogeochemical Characteristics and Controlling Factors of Carlin-type Gold Mining Area Based on Hydrochemistry and Sulfur Isotope].

Mining activities change the groundwater level and flow conditions through pumping and drainage, which enhances the interaction between groundwater and aquifer rocks; mine drainage is discharged into the surface water system, which affects the whole karst water hydrogeochemical process. Based on hydrogeochemistry and the δ34S isotope, the hydrogeochemical processes, characteristics, and main controlling factors for waste water, karst groundwater, and surface water in a typical Carlin gold mining area and its surrounding areas were revealed. The results showed that:chemical compositions of groundwater and surface water unaffected by gold mining activities were mainly controlled by the weathering of limestone and dolomitic limestone; Ca2+, Mg2+, and HCO3- were main ions; and the water chemical types were Ca-HCO3. The mine wastewater and its downstream receiving water were affected by the dissolution of carbonate and silicate minerals, and cation exchange also played a role; the main ions were Ca2+, Mg2+, Na+, and SO42-, and the hydrochemical type gradually evolved from Ca-HCO3 to Ca-SO4. SO42- was the characteristic component in various water bodies affected by mining, and the concentration of SO42- gradually decreased from top to bottom in the well. The values of δ34S for unaffected groundwater and surface water were positive, and SO42- was mainly derived from realgar oxidation. Conversely, mine wastewater and downstream water were negative, SO42- was mainly influenced by the mixing action of realgar oxidation and meteoric precipitation, and pyrite also contributed to a certain extent. At the same time, NO3- came from agricultural fertilizer and rural domestic sewage discharge directly. Principal component analysis (PCA) further demonstrated:sulfide mineral oxidation and mining activities were the main controlling factors for the water chemical composition of mine wastewater and downstream water, whereas unaffected groundwater and surface water were mainly influenced by water-rock (carbonate rock) interactions. Agricultural fertilizer and rural sewage discharge also had a certain influence. Therefore, the study area should strengthen the interception of surface water, control-block-management of sulfide oxidation, rural domestic sewage treatment, and agricultural fertilizer.

Comparison of the Total, Diazotrophic and Ammonia-Oxidizing Bacterial Communities Between Under Organic and Conventional Greenhouse Farming.

Organic greenhouse farming is an innovative system that may maintain a high yield and healthy agroecosystem. There have been no rigorous studies on the comparison of total and nitrogen-cycling bacterial community in vegetable soils between organic and conventional farming management at large scale. A survey of bacterial community and nitrogen cycles from soils under organic and conventional greenhouse farming was performed at 30 sites, covering seven soil types with 4 to 18 years of organic farming history. Communities of the total, diazotrophs and ammonia-oxidizing bacteria were studied with high-throughput sequencing of the 16S rRNA, nifH and amoA genes, respectively. Organic greenhouse farming did not influence alpha diversities. Beta diversities among the total (26/30) and diazotrophic (17/19) bacteria differed between farming systems, but compositional differences in ammonia-oxidizing bacteria between the two farming systems were only detected at 6 sites. Despite the effects of farming system on most bacterial genera were varied across different sites, organic greenhouse farming persistently selected for a few genera, possibly for the biodegradation of organic carbon with high molecular weight (Hyphomicrobium, Rubinisphaera, Aciditerrimonas, Planifilum, Phaselicystis, and Ohtaekwangia), but against putative ammonia oxidizing (Nitrosospira, Nitrosopumilus) and diazotrophic (Bradyrhizobium) bacterial genera, as determined by 16S rRNA analysis. Diazotrophic bacteria affiliated with nifH cluster 1J were preferentially associated with organic greenhouse farming, in contrast to Paenibacillus borealis. In summary, this study provides insights into the complex effects of organic greenhouse farming on the total, diazotrophic and ammonia oxidizing bacterial communities across different environmental context.

Molecular characterization and nutritional regulation of carnitine palmitoyltransferase (CPT) family in grass carp (Ctenopharyngodon idellus).

The carnitine palmitoyltransferase (CPT) gene family plays an essential role in fatty acid ß-oxidation in the mitochondrion. We identified six isoforms of the CPT family in grass carp and obtained their complete coding sequences (CDS). The isoforms included CPT 1α1a, CPT 1α1b, CPT 1α2a, CPT 1α2b, CPT 1ß, and CPT 2, which may have resulted from fish-specific genome duplication. Sequence analysis showed that the predicted protein structure was different among the CPT gene family members in grass carp. The N-terminal domain of grass carp CPT 1α1a, CPT 1α1b, CPT 1α2a, and CPT 1α2b contained two transmembrane region domains and two acyltransferase choActase domains that exist in human and mouse proteins also; however, only one acyltransferase choActase domain was found in grass carp CPT 1ß. The grass carp CPT 2 had two acyltransferase choActase domains. The grass carp CPT 1α1b, CPT 1α2a, CPT 1α2b, and CPT 1ß contained 18 coding exons, while CPT 1α1a and CPT 2 consisted of 17 coding exons and 5 coding exons, respectively. The mRNA of the six CPT isoforms was expressed in a wide range of tissues, but the mRNA abundance of each CPT showed tissue-dependent expression patterns. The expression of CPT 1α1a, CPT 1α2a, and CPT 1ß at 48h post-feeding was significantly increased in the liver (P<0.01, P<0.05, and P<0.01, respectively). The diverse responses of multiple isoforms in the liver during nutritional limitation suggest that they may play different roles in fatty acid ß-oxidation.

Lipolytic enzymes involving lipolysis in Teleost: Synteny, structure, tissue distribution, and expression in grass carp (Ctenopharyngodon idella).

Lipolysis is the biochemical pathway responsible for the sequential hydrolysis of triacylglycerols (TAGs) stored in cellular lipid droplets. Three enzymes are known to participate in TAGs hydrolysis, including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase (MGL), and each is present in mammals as only one isoform. Here we show that the genome of grass carp (Ctenopharyngodon idella) and other teleosts codes for one ATGL, two HSLs, and one MGL isoforms. Two isoforms of HSL gene, HSLa and HSLb, derived from paralogous genes that could be originated from teleost-specific genome duplication (TSGD) event. The genes encoding for fish ATGL and MGL were conserved and contained nine and seven coding exons, respectively. However, two isoforms of HSL gene had a remarkable variation in gene structure, such as HSLa gene contained ten and HSLb contained thirteen exons. All three enzymes, including two isoforms of HSL, were expressed in a wide range of tissues, but the abundance of each gene mRNA showed the tissue-dependent expression patterns. During fasting, only ATGL and HSLa showed a significant increase in adipose tissue and adipocyte, indicating that ATGL and HSLa may be the main rate-limiting enzymes controlling the hydrolysis of TAGs in fasting-induced lipolysis. Different expression of HSLa and HSLb suggests that they might serve different roles in fasting-induced lipolysis. These results provide evidence about the conservation and divergence of genes of fish lipolytic enzymes.

Bmi-1 expression predicts prognosis for patients with gastric carcinoma.

BACKGROUND AND OBJECTIVE: The Bmi-1 gene is a transcriptional repressor involved in oncogenesis in various human cancers. Here, we examine Bmi-1 expression in gastric carcinoma (GC) and investigates whether its expression correlates with patient prognosis. METHODS: Immunohistochemistry was performed using an anti-Bmi-1 antibody on primary tumor samples of 146 cases of GC. The association between Bmi-1 expression and the clinicopathological status and prognosis of GC patients was statistically analyzed. Furthermore, reverse transcription-PCR (RT-PCR) and Western blotting were performed to determine the expression levels of Bmi-1 in an additional 8 GC and the adjacent non-cancerous samples. RESULTS: Using immunohistochemistry, we found that 99 of 146 paraffin-embedded GC samples expressed Bmi-1 extensively. Statistical analysis showed that Bmi-1 overexpression was highly correlated with tumor size, clinical stage, lymph node metastasis and T classification (P < 0.05), Patients with Bmi-1 expression had shorter overall survival time than those without Bmi-1 expression (P < 0.01). Multivariate analysis indicated that Bmi-1 expression is an independent prognostic factor of GC. RT-PCR and Western blotting showed that Bmi-1 was up-regulated at both the transcriptional and translational levels in the GC tissues compared with the adjacent non-cancerous tissues. CONCLUSIONS: Bmi-1 may serve as a valuable marker for diagnosis and prognosis of GC.

[Association of Bmi-1 mRNA expression with differentiation, metastasis and prognosis of gastric carcinoma].

OBJECTIVE: To investigate the association of B cell-specific MLV integration site-1 (Bmi-1) mRNA expression level with the differentiation, metastasis and prognosis of gastric carcinoma. METHODS: Tissue specimens were obtained from 42 patients undergoing surgery for gastric carcinomas. Reverse transcriptional PCR (RT-PCR) was performed for amplification of Bmi-1 mRNA from the 42 tumor tissues and matched adjacent normal tissues, and the differential Bmi-1 mRNA expression was analyzed for its association with the clinical manifestations of the patients. RESULTS: Bmi-1 mRNA expression was detected in all the gastric carcinoma tissues and normal tissues adjacent to the carcinoma using fluorescence method, and in 29 cases, Bmi-1 mRNA expression was significantly higher in the tumor tissues than in the adjacent tissues. Expression of Bmi-1 mRNA was highly correlated with tumor size, lymph node metastasis and T classification (P<0.05), but not with the patients' gender, age, or tumor differentiation (P>0.05). The survival rate was much lower in patients positive for Bmi-1 mRNA expression than in those without Bmi-1 mRNA expression. CONCLUSIONS: Bmi-1 mRNA expression is correlated to differentiation and metastasis of gastric carcinoma and may facilitate its prognostic evaluation. Bmi-1 may serve as a marker for assessing the progression of gastric carcinoma and provide assistance for clinical therapeutic decisions.

[Biodistribution of (99m)Tc-labeled anti-VEGF mAb 5-FU loaded polylactic acid nanoparticles in human gastric carcinoma xenografts].

OBJECTIVE: To prepare (99m)Tc-labeled Anti-VEGF mAb 5-FU loaded polylactic acid nanoparticles ((99m)Tc-Ab-5-FU-NPs) and investigate its biodistribution in human gastric carcinoma xenografts. METHODS: (99m)Tc-Ab-5-FU-NPs were prepared by labeling Ab-5-FU-NPs with (99m)Tc using improved Schwarz method. After isolation of (99m)Tc-Ab-5-FU-NPs using SephadexG250 column, the labeling ratio and radiochemical purity were determined using chromatography. The immunocompetence of (99m)Tc- Ab-5-FU-NPs was detected by ELISA and immunohistochemistry. (99m)Tc-Ab-5-FU-NPs were then injected via the tail vein into SCID mice bearing human gastric carcinoma, and (99m)Tc labeled mice-derived monoclonal IgG loaded polylactic acid nanoparticles were used as the control, followed by radioimmunoscintigraphic imaging at 2 and 6 h. The radioactive count and radioactive ratio of the tumor and non-tumor tissue (T/NT) in the animal models were calculated using ROI technique. After imaging at 24 h, SCID mice were sacrificed and the radioactive distribution, the %ID/g, as well as the T/NT radioactive ratio were examined, respectively. The concentrations of 5-FU in the tumor and blood were also detected using HPLC method. RESULTS: The labeling ratio of (99m)Tc-Ab-5-FU-NPs was 90%-95%. (99m)Tc-Ab-5-FU-NPs were detected in the tumor tissues by radioimmunoimaging 2 h after the injection. ID%/g in the tumor tissues at 2 and 6 h were both significantly higher than that of the control group. Both the ID%/g in tumor tissues and radioactive ratio of tumor and blood at 6 h were higher than those at 2 h, and the concentration of 5-FU in experimental group increased continuously with time and was significantly higher than that in control group. CONCLUSIONS: (99m)Tc-Ab-5-FU-NPs prepared in this study can meet the demands of radioimmunoimaging, and the anti-VEGF monoclonal antibody possesses reliable immune targeting ability. Six hours after injection, (99m)Tc-Ab-5-FU-NPs can specifically accumulate in the tumor tissues in human gastric carcinoma xenografts at high concentration.