Identification of priority management areas for non-point source pollution based on critical source areas in an agricultural watershed of Northeast China.

Identification of critical source areas (CSAs) for non-point source (NPS) pollution is of great significance for environment governance and prevention. However, the CSAs are generally characterized as great spatial dispersion, and spatially heterogeneous precipitation has a great influence on the spatial distribution of nutrient yields. Therefore, we identify the CSAs for nutrient yields in an agricultural watershed of Northeast China at hydrological response units (HRUs) scale based on the Soil and Water Assessment Tool (SWAT), assess the impacts of spatially heterogeneity of precipitation on the identification of the CSAs, analyze the sensitivity of nutrient yields to precipitation by scenarios analysis method, and further identify priority management areas (PMAs) that have poor ability to retain nutrients. The results showed that the CSAs for nutrient yields identified by uniform precipitation showed greater fluctuation range and coverage area than actual precipitation; the major prevention areas of total nitrogen (TN) yield were mainly distributed in regions nearby main stem of lower reaches, while that of total phosphorus (TP) yield were mostly located in urban area nearby outlet of the watershed; the identification of the PMAs significantly decreased the CSAs for TN yield, whereas that for TP yield was no significant difference with the CSAs. This study could provide scientific guidance for the NPS pollution governance and prevention.

A major QTL located on chromosome V associates with in vitro tuberization in a tetraploid potato population.

The cultivated potato (Solanum tuberosum L.) is an autotetraploid species. The complexity of tetrasomic inheritance and the lack of pure lines increase the difficulty of genetic analysis of the inherited characteristics. Tuberization is the determinant step for economic yield of potato. To understand the complex genetic basis of tuberization of the cultivated potato, we developed linkage maps for a tetraploid population (F1) of 237 genotypes and mapped QTLs for the percent of in vitro tuberized plantlets (% IVT). The paternal map for E108 (well tuberized) covered 948 cM and included 12 linkage groups, all of which contained all four homologous chromosomes. The maternal map for E20 (nontuberized) covered 1,286 cM and included 14 linkage groups, 12 of which contained all four homologous chromosomes. All 12 chromosomes of potato were tagged using the SSR markers. A major QTL (MT05) with additive effect was detected on chromosome V of E108 which explained 16.23 % of the variation for % IVT, and two minor QTLs (mt05 and mt09) displaying simplex dominant effects were located on chromosome V and chromosome IX of E20 which explained 5.33 and 4.59 % of the variation for % IVT, respectively. Based on the additive model of MT05, the segregation ratio of the gametic genotypes (Q-: qq = 5:1) matched the ratio of the tuberized genotypes to the nontuberized genotypes in the population suggesting that the segregation of in vitro tuberization in this population is controlled by a major-effect gene or genes. The mapping results of three important candidate genes indicated that the QTL causal genes detected in our study are new. In this study, we developed the almost complete linkage maps of a tetraploid population, identified a major QTL on chromosome V affecting in vitro tuberization, suggested a major-effect gene with minor modifiers model controlling this trait and found that the QTLs identified here correspond to new tuberization genes. Our work provides new and useful information about the genetic basis for tuberization of this autotetraploid crop.

Transcriptome analysis reveals novel genes potentially involved in photoperiodic tuberization in potato.

Potato microtuber produced in vitro provides a model system to investigate photoperiod-dependent tuberization. However, the genes associated with potato tuberization remain to be elucidated. The present research involved three potato clones with distinct tuberization response to changes of photoperiod. Digital Gene Expression (DGE) Tag Profiling analysis of the short-day-sensitive clone identified 2218 genes that were regulated by day length. Both GO and KEGG pathway analysis provided insights into predominant biological processes and pathways, and enabled the selection of 56 genes associated with circadian rhythmicity, signal transduction, and development. Quantitative transcriptional analysis in the selected clones revealed 5 genes potentially associated with photoperiodic tuberization, which were predicted to encode a DOF protein, a blue light receptor, a lectin, a syntaxin-like protein, and a protein with unknown function. Our results strongly suggest that potato tuberization may be largely controlled by the homologs of genes shown to regulate flowering time in other plants.

Characterization of a Conjugative Multidrug Resistance IncP-2 Megaplasmid, pPAG5, from a Clinical Pseudomonas aeruginosa Isolate.

The spread of resistance genes via horizontal plasmid transfer plays a significant role in the formation of multidrug-resistant (MDR) Pseudomonas aeruginosa strains. Here, we identified a megaplasmid (ca. 513 kb), designated pPAG5, which was recovered from a clinical multidrug-resistant P. aeruginosa PAG5 strain. The pPAG5 plasmid belonged to the IncP-2 incompatibility group. Two large multidrug resistance regions (MDR-1 and MDR-2) and two heavy metal resistance operons (merEDACPTR and terZABCDE) were identified in the pPAG5 plasmid. Genetic analysis demonstrated that the formation of MDR regions was mediated by several homologous recombination events. Further conjugation assays identified that pPAG5 could be transferred to P. aeruginosa but not Escherichia coli. Antimicrobial susceptibility testing on transconjugants demonstrated that pPAG5 was capable of transferring resistance genes to transconjugants and producing a multidrug-resistant phenotype. Comparative analysis revealed that pPAG5 and related plasmids shared an overall similar backbone, including genes essential for replication (repA), partition (par), and conjugal transfer (tra). Further phylogenetic analysis showed that pPAG5 was closely related to plasmids pOZ176 and pJB37, both of which are members of the IncP-2-type plasmid group. IMPORTANCE The emergence and spread of plasmid-associated multidrug resistance in bacterial pathogens is a key global threat to public health. It is important to understand the mechanisms of the formation and evolution of these plasmids in patients, hospitals, and the environment. In this study, we detailed the genetic characteristics of a multidrug resistance IncP-2 megaplasmid, pPAG5, and investigated the formation of its MDR regions and evolution. To the best of our knowledge, plasmid pPAG5 is the largest multidrug resistance plasmid ever sequenced in the Pseudomonas genus. Our results may provide further insight into the formation of multidrug resistance plasmids in bacteria and the molecular evolution of plasmids.

Protecting Effect of Bacillus coagulans T242 on HT-29 Cells Against AAPH-Induced Oxidative Damage.

The aim of the present study was to investigate the in vitro antioxidant potential of Bacillus coagulans T242. B. coagulans T242 showed better antioxidant activities, including the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging ability, lipid peroxidation inhibiting ability and reducing ability, than those exerted by Lactobacillus rhamnosus GG (LGG). B. coagulans T242 positively regulated the expression of the nuclear factor erythroid 2-relatedfactor 2/Kelch-like ECH-associated protein-1 (Nrf2/Keap1) pathway-related proteins (Nrf2, Keap1, heine oxygenase-1 (HO-1)); increased antioxidant enzymes (glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD)); reduced the content of malondialdehyde (MDA) level; decreased the expression of inflammatory-related cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α); and thus increased the survival rate in 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-damaged HT-29 cells. This study proved that B. coagulans T242 exerted antioxidative effects by quenching oxygen free radicals and activating the Nrf2 signaling pathway in HT-29 cells.

The palmitoylation of AEG-1 dynamically modulates the progression of hepatocellular carcinoma.

Rationale: Protein palmitoylation is tightly related to tumorigenesis or tumor progression as many oncogenes or tumor suppressors are palmitoylated. AEG-1, an oncogene, is commonly elevated in a variety of human malignancies, including hepatocellular carcinoma (HCC). Although AEG-1 was suggested to be potentially modified by protein palmitoylation, the regulatory roles of AEG-1 palmitoylation in tumor progression of HCC has not been explored. Methods: Techniques as Acyl-RAC assay and point mutation were used to confirm that AEG-1 is indeed palmitoylated. Moreover, biochemical experiments and immunofluorescent microscopy were applied to examine the cellular functions of AEG-1 palmitoylation in several cell lines. Remarkably, genetically modified knock-in (AEG-1-C75A) and knockout (Zdhhc6-KO) mice were established and subjected to the treatment of DEN to induce the HCC mice model, through which the roles of AEG-1 palmitoylation in HCC is directly addressed. Last, HCQ, a chemical compound, was introduced to prove in principal that elevating the level of AEG-1 palmitoylation might benefit the treatment of HCC in xenograft mouse model. Results: We showed that AEG-1 undergoes palmitoylation on a conserved cysteine residue, Cys-75. Blocking AEG-1 palmitoylation exacerbates the progression of DEN-induced HCC in vivo. Moreover, it was demonstrated that AEG-1 palmitoylation is dynamically regulated by zDHHC6 and PPT1/2. Accordingly, suppressing the level of AEG-1 palmitoylation by the deletion of Zdhhc6 reproduces the enhanced tumor-progression phenotype in DEN-induced HCC mouse model. Mechanistically, we showed that AEG-1 palmitoylation adversely regulates its protein stability and weakens AEG-1 and staphylococcal nuclease and tudor domain containing 1 (SND1) interaction, which might contribute to the alterations of the RISC activity and the expression of tumor suppressors. For intervention, HCQ, an inhibitor of PPT1, was applied to augment the level of AEG-1 palmitoylation, which retards the tumor growth of HCC in xenograft model. Conclusion: Our study suggests an unknown mechanism that AEG-1 palmitoylation dynamically manipulates HCC progression and pinpoints that raising AEG-1 palmitoylation might confer beneficial effect on the treatment of HCC.

[Impact of Spatial Heterogeneity of Precipitation on the Area Change in Critical Source Area of Non-point Sources Pollution].

Aiming at non-point sources pollution in the agricultural areas with large topographic fluctuations and spatial differences in precipitation, a SWAT model was used to evaluate the spatial variations in the critical source areas (CSAs) of total nitrogen (TN) and total phosphorus (TP) under two precipitation scenarios, i.e., heterogeneous precipitation and uniform precipitation. A change in the CSAs identified based on the two precipitation scenarios during the study period were statistically calculated, and the relationship between the CSAs and precipitation variables was discussed. The study results showed that when the total precipitation was the same, the variation tendency of the identified CSAs for TN and TP under the two precipitation scenarios were similar, and very close for a few years. According to the results of the pair t test, the CSAs of TP were not affected by the spatial variation of precipitation, while the change in CSAs for TN was more significant under different precipitation scenarios, which is likely due to the difference in the physical properties of nitrogen and phosphorus. The correlation analysis between the CSAs of TN and TP with precipitation variables showed that the variation in the CSAs of TP was positively correlated with the precipitation variables in the same year, while the variation in the CSAs of TN was strongly related to the precipitation variables of the previous year. The results obtained in this study are of great significance for further exploring the impact of uncertainty of precipitation, which is an important driving factor, on the CSAs of non-point sources pollution and the governance of agricultural non-point sources pollution.