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Ammonia is a common environmental pollutant in aquatic ecosystem and is also a significant concern in closed aquaculture systems. The threat of ammonia has been increasing with rising anthropogenic activities including intensified aquaculture. In this study, we aimed to investigate ammonia toxicity and metabolism mechanisms in the hepatopancreas, a major organ for Vitellogenin (Vtg) synthesis and defending against ammonia stress, of female swimming crab Portunus trituberculatus which is an important fishery and aquaculture species, by integrating physiological, transcriptome and metabolome analyses. The results revealed that ammonia exposure (10 mg/L, an environmentally relevant concentration) resulted in a remarkable reduction in vtg expression and depression of multiple signaling pathways for reproductive regulators including methyl farnesoate, ecdysone and neuroparsin, demonstrating for the first time that ammonia impairs swimming crab female reproduction. In addition, a number of important genes and metabolites in glycolysis, the Krebs cycle, fatty acid β-oxidation and synthesis were significantly downregulated, indicating that changes in ammonia levels lead to a general depression of energy metabolism in hepatopancreas. After ammonia exposure, an increased level of urea and a reduction of amino acid catabolism were observed in hepatopancreas, suggesting that urea cycle was utilized to biotransform ammonia, and amino acid catabolism was decreased to reduce endogenous ammonia generation. Furthermore, antioxidant systems were altered following ammonia exposure, which was accompanied by proteins and lipid oxidations, as well as cellular apoptosis. These results indicate that ammonia leads to metabolic suppression, oxidative stress and apoptosis in P. trituberculatus hepatopancreas. The findings improve the understanding for the mechanisms of ammonia toxicity and metabolism in P. trituberculatus , and provide valuable information for assessing potential ecological risk of environmental ammonia and improving aquaculture management. [Display omitted] • Ammonia exposure (10 mg/L for 96 h, the same hereinafter) impairs reproduction of female swimming crab. • Ammonia exposure leads to a general depression of energy metabolism in hepatopancreas. • Ammonia exposure results in impaired antioxidant defense and induces oxidative damage and apoptosis in hepatopancreas. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we study the constrained shrinking dimer dynamics (CSDD) which leads to numerical procedures for locating saddle points (transition states) associated with an energy functional defined on a constrained manifold. We focus on the most generic case corresponding to a constrained stationary point where the projected Hessian of the energy onto the tangent hyperplane of the constrained manifold has only one unstable direction and demonstrate, in this case, the local stability of the CSDD. We examine various numerical implementation issues and consider some interesting applications of CSDD including the computation of periodic centroidal Voronoi tessellations, generalized Thomson problems about particle/charge distribution on the unit sphere, and the critical nuclei morphology in binary phase transformations. [Copyright &y& Elsevier]

Abstract: Cononsolvency-induced micellization kinetics of a pyrene end-labeled diblock copolymer of N-isopropylacrylamide and oligo(ethylene glycol) methyl ether methacrylate, Py-PNIPAM-b-POEGMA, was investigated in detail via a combination of stopped-flow light-scattering and fluorescence techniques. Upon a stopped-flow jump from pure methanol to proper methanol/water mixtures, scattered light intensity exhibited an initial increase and then stabilized out; whereas the time-dependence of monomer to excimer fluorescence intensity ratios () revealed an abrupt increase followed by a gradual decrease to plateau values. The dynamic traces of scattered intensity can be well fitted by double exponential functions, the obtained and can be ascribed to processes of forming quasi-equilibrium micelles and their relaxation into final equilibrium states, respectively. On the other hand, a triple exponential function was needed to fit the dynamic traces of , leading to three characteristic relaxation times (, , and ). It was found that the time scales of and obtained from stopped-flow light scattering were in general agreement with and obtained from stopped-flow fluorescence. Considering that excimer fluorescence is extremely sensitive to small aggregates, the newly detected fast process () by stopped-flow fluorescence should be ascribed to the early stage of micellization, i.e., the burst formation of small transient micelles, in which light scattering detection was still not sensitive enough. These small transient micelles fused and grew into quasi-equilibrium micelles, which then slowly relaxed into the final equilibrium state. [Copyright &y& Elsevier]

Abstract: The kinetics and mechanism of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt, p-toluidine hydrochloride (PTHC), were investigated by stopped-flow with light scattering detection. Spherical sodium dodecyl sulfate (SDS) micelles transform into short ellipsoidal shapes at low salt concentrations ([PTHC]/[SDS], and 0.4). Upon stopped-flow mixing aqueous solutions of spherical SDS micelles with PTHC, the scattered light intensity gradually increases with time. Single exponential fitting of the dynamic traces leads to characteristic relaxation time, , for the growth process from spherical to ellipsoidal micelles, and it increases with increasing SDS concentrations. This suggests that ellipsoidal micelles might be produced by successive insertion of unimers into spherical micelles, similar to the case of formation of spherical micelles as suggested by Aniansson–Wall (A–W) theory. At , rod-like micelles with much higher axial ratio form. The scattered light intensity exhibits an initially abrupt increase and then levels off. The dynamic curves can be well fitted with single exponential functions, and the obtained decreases with increasing SDS concentration. Thus, the growth from spherical to rod-like micelles might proceed via fusion of spherical micelles, in agreement with mechanism proposed by Ikeda et al. At and 0.6, the apparent activation energies obtained from temperature dependent kinetic studies for the micellar growth are 40.4 and 3.6 kJ/mol, respectively. The large differences between activation energies for the growth from spherical to ellipsoidal micelles at low and the sphere-to-rod transition at high further indicate that they should follow different mechanisms. Moreover, the sphere-to-rod transition kinetics of sodium alkyl sulfate with varying hydrophobic chain lengths (, 12, 14, and 16) are also studied. The longer the carbon chain lengths, the slower the sphere-to-rod transition. [Copyright &y& Elsevier]

The objective of this study was to investigate the gel strength, chemical interactions, water distribution, SDS-PAGE and rheological characteristics of surimi washed with different pH values and monovalent/divalent cations. There was higher gel strength in surimi washed with monovalent cations at pH 3.0 or 7.0 and divalent cations at pH 3.0 or 9.0. More divalent cations in the washing delayed surimi protein denaturation. Myosin heavy chain and actin were more intense in surimi washed with 0.25% Na+ or 0.5% other cations. The gel relaxation time was shortened in surimi washed with an increased ionic strength. The gel disulfide bond was decreased in surimi washed at pH 3.0 or 9.0, whereas hydrophobic interactions and ionic and hydrogen bonds were increased in those at pH 5.0 or 7.0. In general, washing with different pH values and monovalent/divalent cations could significantly influence the gel network structure of surimi. • Gel strength was higher in surimi washed with 0.5% Na+ or 0.25% others. • Increasing ionic strength in washing shortened the surimi gel's relaxation time. • More divalent cations in washing delayed the denaturation of surimi protein. • Surimi washed with 0.5% K+, Ca2+, and Mg2+ had more intense bands. • The gel disulfide bond was decreased in surimi washed at pH 3.0 or 9.0. [ABSTRACT FROM AUTHOR]

Fermenting yogurt with plant-based ingredients for nutritional and health benefits is an emerging trend. The growth kinetics, metabolomics changes, and antioxidant activity of probiotics in fermented highland barley-based yogurt were investigated in this study. Highland barley (HB) (Hordeum vulgare , Poaceae) enzyme hydrolyte was mixed with soy protein concentrate as ingredients for preparation of HB-based yogurt fermented by Lactobacillus bulgaricus VHProbi R03 and Streptococcus thermophilus VHProbi R08. After 4 h of fermentation, both strains grew to the stationary phase with the viable counts of 1.9 × 108 CFU/mL for each strain. The viable bacterial count in HB-based yogurt was approximately 9.3 × 107 CFU/mL after 21 days of storage at 4 °C. Compared with the control yogurt made using white sugar (as a substitute for HB enzyme hydrolyte) and soy protein concentrate, HB-based yogurt had higher concentrations of cyclic adenosine monophosphate, glycerophosphocholine, hypoxanthine and arginyl-proline, total phenolic compounds, and flavonoids, greater antioxidant activity, and higher sensory scores. In conclusion, HB-based yogurt is a potential novel food product that provides a good source of probiotics and antioxidants. • Highland barley-based yogurt has higher antioxidant activity. • Total phenolic and flavonoid contents of Highland barley-based yogurt significantly higher after fermented. • 27 top metabolites with significant changes in fermented Highland barley-based yogurt. • The properties of Highland barley-based yogurt were stable during storage. [ABSTRACT FROM AUTHOR]

Abstract: EPR spin-trapping experiments were carried out using the three-component soluble methane monooxygenase (MMO). Spin-traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), α-4-pyridyl-1-oxide N-tert-butylnitrone (POBN), and nitrosobenzene (NOB) were used to investigate the possible formation of substrate radical intermediates during catalysis. In contrast to a previous report, the NADH-coupled oxidations of various substrates did not produce any trapped radical species when DMPO or POBN was present. However, radicals were detected by these traps when only the MMO reductase component and NADH were present. DMPO and POBN were found to be weak inhibitors of the MMO reaction. In contrast, NOB is a strong inhibitor for the MMO-catalyzed nitrobenzene oxidation reaction. When NOB was used as a spin-trap in the complete MMO system with or without substrate, EPR signals from an NOB radical were detected. We propose that a molecule of NOB acts simultaneously as a substrate and a spin-trap for MMO, yielding the long-lived radical and supporting a stepwise mechanism for MMO. [Copyright &y& Elsevier]

Major depressive disorder (MDD) is a common, serious, debilitating mental illness. Protein phosphatase Mg2+/Mn2+-dependent 1F (PPM1F), a serine/threonine phosphatase, has been reported to have multiple biological and cellular functions. However, the effects of PPM1F and its neuronal substrates on depressive behaviors remain largely unknown. Here, we showed that PPM1F is widely distributed in the hippocampus, and chronic unpredictable stress (CUS) can induce increased expression of PPM1F in the hippocampus, which was correlated with depression-associated behaviors. Overexpression of PPM1F mediated by adeno-associated virus (AAV) in the dentate gyrus (DG) produced depression-related behaviors and enhanced susceptibility to subthreshold CUS (SCUS) in both male and female mice, while, knockout of PPM1F in DG produced antidepressant phonotypes under stress conditions. Whole-cell patch-clamp recordings demonstrated that overexpression of PPM1F increased the neuronal excitability of the granule cells in the DG. Consistent with neuronal hyperexcitability, overexpression of PPM1F regulated the expression of certain ion channel genes and induced decreased phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CAMKII) and Adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) in hippocampus. These results suggest that PPM1F in the DG regulates depression-related behaviors by modulating neuronal excitability, which might be an important pathological gene for depression or other mental diseases. • CUS induces depression-related behaviors and increases the expression of PPM1F in hippocampus. • Overexpression of PPM1F in hippocampal DG produces depression-related behaviors. • Knockout of PPM1F in hippocampal DG produces antidepressant phonotypes. • Manipulation of PPM1F affects the excitability of DG granule cells, the expression of ion channel genes, and phosphorylation levels of CAMKII and AMPK. [ABSTRACT FROM AUTHOR]