Appearance of direct-acting mutagenicity of various foodstuffs produced in Japan and Southeast Asia on nitrite treatment

After nitrite treatment, various kinds of pickled vegetables and sun-dried fishes produced in Japan showed direct-acting mutagenicity on Salmonella typhimurium TA100, inducing 1900-18000 revertants/g. Kimchis, sun-dried fishes, sun-dried squid, soy sauces, fish sauces, bean pastes and shrimp paste produced in Korea, the Philippines and Thailand also showed direct-acting mutagenicity after nitrite treatment. All soy sauces and fish sauces tested contained as much tyramine as 17-1020 micrograms/ml, but very low or undetectable amounts of (-)-(1S,3S)- and (-)-(1R,3S)-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids.     

Staurosporine-induced cell death in salmonid cells: the role of apoptotic volume decrease, ion fluxes and MAP kinase signaling

Apoptotic cell death in mammalian models is frequently associated with cell shrinkage. Inhibition of apoptotic volume decrease (AVD) is cytoprotective, suggesting that cell shrinkage is an important early event in apoptosis. In salmonid hepatoma and gill cells staurosporine induced apoptosis, as assessed by activation of effector caspases, nuclear condensation, and a decrease of mitochondrial membrane potential (MMP), and these changes were accompanied by cell shrinkage. The Cl⁻ transport inhibitor DIDS and the K⁺ channel inhibitor quinidine prevented AVD, but only DIDS inhibited apoptosis. Other Cl⁻ flux inhibitors, as well as a pan-caspase inhibitor, did not prevent cell shrinkage, but still prevented caspase activation. Furthermore, regulatory volume decrease (RVD) under hypotonic conditions was not facilitated, but diminished in apoptotic cells. Since all transport inhibitors used blocked RVD, but only DIDS and quinidine inhibited AVD, the ion transporters involved in both processes are apparently not identical. In addition, our data indicate that inhibition of Cl⁻ fluxes rather than blocking cell shrinkage or K⁺ fluxes is important for preventing apoptosis. In line with this, inhibition of MAP kinases reduced RVD and not AVD, but still diminished caspase activation. Finally, we observed that MAP kinases were activated upon staurosporine treatment and that at least activation of ERK was prevented when AVD was inhibited.     

Improving magnesium uptake,photosynthesis and antioxidant enzyme activities of watermelon by grafting onto pumpkin rootstock under low magnesium

Background and aims

Magnesium (Mg) is an essential macronutrient that plays an important role in numerous physiological and biochemical processes of plant. However, Mg deficiency commonly occurs worldwide. Watermelon is an important crop that often suffers from Mg deficiency. This study aims to test whether watermelon performance can be improved by grafting onto rootstocks under low Mg and to clarify the underlying physiological mechanism.

Methods

Self-grafted, bottle gourd (Jingxinzhen No.1) and pumpkin (Jingxinzhen No.4) rootstock-grafted plants were treated with three Mg concentrations: 2.0 mM (normal condition), 0.4 mM (moderate stress), and 0.04 mM (severe stress) for 16 days under hydroponic conditions. Ungrafted watermelon and pumpkin were treated with 2.0 mM and 0.04 mM for 12 days.

Results

The growth of the plants was not affected by 0.4 mM Mg; however, plant growth decreased under 0.04 mM Mg in all graft combinations compared with control (2.0 mM Mg). Pumpkin rootstock grafting significantly increased watermelon growth under low Mg stress (0.04 mM Mg), compared with self-grafted and bottle gourd-grafted plants. The Mg²⁺ uptake of watermelon plants was increased by grafting onto pumpkin rootstocks, however, root-to-shoot transport capacity of Mg²⁺ was similar compared with self-grafted plants under 0.04 mM Mg. Gene expression analysis showed that magnesium transporter genes MGT1, MGT3, MGT4, and MGT5 may play an important role in higher Mg²⁺ uptake of pumpkin root. The photosynthetic parameters and activities of superoxide dismutase, peroxidase and catalase were significantly higher, but malonaldehyde (MDA) content were lower in the pumpkin rootstock grafted plants compared with other graft combinations under 0.04 mM Mg.

Conclusion

Our results provide strong evidence that pumpkin rootstock ‘Jinxinzhen No. 4’ grafting can improve watermelon performance under low Mg stress. The enhanced plant performance is attributed to higher root Mg²⁺ uptake and the improvement of photosynthesis and antioxidant enzyme activities.

     

Selenium (Se) Seed Priming Induced Growth and Biochemical Changes in Wheat Under Water Deficit Conditions

Insufficient stand establishment at early growth stages in wheat (Triticum aestivum L.) due to drought stress is a major problem that limits overall efficiency and yield of crop. Priming of seed is an effective method for raising seed performance and improving tolerance of crops to abiotic stresses especially drought. The seeds of two local wheat cultivars (Kohistan-97 and Pasban-90) were soaked in distilled water or sodium selenate solutions of 25, 50, 75, and 100 μM for 1/2 or 1 h at 25 °C and later re-dried to their original moisture levels before sowing. One-hour priming significantly increased root length stress tolerance index, dry matter stress tolerance index, and total biomass of seedlings; however, no significant effect of changing duration of Se seed priming was observed on plant height stress tolerance index and shoot/root ratio. Among cultivars, Kohistan-97 was found to be more responsive to Se seed treatment as 1 h priming at 100 μM significantly increased its total biomass by 43 % as compared to control treatment. Although biomass of seedlings was not affected with Se seed priming under normal conditions, but it increased significantly with increase in rates of Se under drought stress conditions. One-hour priming at 75 μM increased the total sugar content and total free amino acids in both wheat cultivars. A more significant decrease in soluble proteins of seedlings was observed by 1 h priming than 1/2 h priming under drought stress conditions.     

Insights from Streptococcus pneumoniae glucose kinase structural model

Streptococcus pneumonia is the common cause of sepsis and meningitis. Emergence of multiple antibiotic resistant strains in the community‐acquired bacterium is catastrophic. Glucose kinase (GLK) is a regulatory enzyme capable of adding phosphate group to glucose in the first step of streptomycin biosynthesis. The activity of glucose kinase was regulated by the Carbon Catabolite Repression (CCR) system. Therefore, it is important to establish the structure‐function relation of GLK in S. pneumoniae. However, a solved structure for S. pneumoniae GLK is not available at the protein data bank (PDB). Therefore, we created a model of GLK from S. pnemoniae using the X‐ray structure of Glk from E. faecalis as template with MODELLER (a comparative modeling program). The model was validated using protein structure checking tools such as PROCHECK, WHAT IF and ProSA for reliability. The active site amino acid Asp114 in the template is retained in S. pneumoniae GLK model (Asp115). Solvent accessible surface area (ASA) analysis of the GLK model showed that known key residues playing important role in active site for ligand binding and metal ion binding are buried and hence not accessible to solvent. The information thus discussed provides insight to the molecular understanding of glucose kinase in S. pneumoniae.     

Accurate prediction of kinase-substrate networks using knowledge graphs

Phosphorylation of specific substrates by protein kinases is a key control mechanism for vital cell-fate decisions and other cellular processes. However, discovering specific kinase-substrate relationships is time-consuming and often rather serendipitous. Computational predictions alleviate these challenges, but the current approaches suffer from limitations like restricted kinome coverage and inaccuracy. They also typically utilise only local features without reflecting broader interaction context. To address these limitations, we have developed an alternative predictive model. It uses statistical relational learning on top of phosphorylation networks interpreted as knowledge graphs, a simple yet robust model for representing networked knowledge. Compared to a representative selection of six existing systems, our model has the highest kinome coverage and produces biologically valid high-confidence predictions not possible with the other tools. Specifically, we have experimentally validated predictions of previously unknown phosphorylations by the LATS1, AKT1, PKA and MST2 kinases in human. Thus, our tool is useful for focusing phosphoproteomic experiments, and facilitates the discovery of new phosphorylation reactions. Our model can be accessed publicly via an easy-to-use web interface (LinkPhinder).