ZntA maintains zinc and cadmium homeostasis and promotes oxidative stress resistance and virulence in Vibrio parahaemolyticus.

Although metals are essential for life, they are toxic to bacteria in excessive amounts. Therefore, the maintenance of metal homeostasis is critical for bacterial physiology and pathogenesis. Vibrio parahaemolyticus is a significant food-borne pathogen that mainly causes acute gastroenteritis in humans and acute hepatopancreatic necrosis disease in shrimp. Herein, we report that ZntA functions as a zinc (Zn) and cadmium (Cd) homeostasis mechanism and contributes to oxidative stress resistance and virulence in V. parahaemolyticus. zntA is remarkably induced by Zn, copper, cobalt, nickel (Ni), and Cd, while ZntA promotes V. parahaemolyticus growth under excess Zn/Ni and Cd conditions via maintaining Zn and Cd homeostasis, respectively. The growth of ΔzntA was inhibited under iron (Fe)-restricted conditions, and the inhibition was associated with Zn homeostasis disturbance. Ferrous iron supplementation improved the growth of ΔzntA under excess Zn, Ni or Cd conditions. The resistance of ΔzntA to H2O2-induced oxidative stress also decreased, and its virulence was attenuated in zebrafish models. Quantitative real-time PCR, mutagenesis, and ß-galactosidase activity assays revealed that ZntR positively regulates zntA expression by binding to its promoter. Collectively, the ZntR-regulated ZntA is crucial for Zn and Cd homeostasis and contributes to oxidative stress resistance and virulence in V. parahaemolyticus.

A modified shuffled frog leaping algorithm with inertia weight.

The shuffled frog leaping algorithm (SFLA) is a promising metaheuristic bionics algorithm, which has been designed by the shuffled complex evolution and the particle swarm optimization (PSO) framework. However, it is easily trapped into local optimum and has the low optimization accuracy when it is used to optimize complex engineering problems. To overcome the shortcomings, a novel modified shuffled frog leaping algorithm (MSFLA) with inertia weight is proposed in this paper. To extend the scope of the direction and length of the updated worst frog (vector) of the original SFLA, the inertia weight α was introduced and its meaning and range of the new parameters are fully explained. Then the convergence of the MSFLA is deeply analyzed and proved theoretically by a new dynamic equation formed by Z-transform. Finally, we have compared the solution of the 7 benchmark functions with the original SFLA, other improved SFLAs, genetic algorithm, PSO, artificial bee colony algorithm, and the grasshopper optimization algorithm with invasive weed optimization. The testing results showed that the modified algorithms can effectively improve the solution accuracy and convergence property, and exhibited an excellent ability of global optimization in high-dimensional space and complex function problems.

Simultaneous determination of twenty-nine active compounds in fuzhengjiedu granules by HPLC-QQQ-MS/MS.

As an empirical medicine of traditional Chinese medicine, Fuzhengjiedu Granules have shown an effect against COVID-19 in clinical and inflammatory animal models. It is formulated with eight herbs, including Aconiti Lateralis Radix Praeparata, Zingiberis Rhizoma, Glycyrrhizae Radix Et Rhizoma, Lonicerae Japonicae Flos, Gleditsiae Spina, Fici Radix, Pogostemonis Herba, and Citri Reticulatae Pericarpium. This study established a high-performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QQQ-MS/MS) method by simultaneously determining 29 active compounds in the granules with significant content differences. Separation by gradient elution using acetonitrile and water (0.1% formic acid) as mobile phases was performed on a Waters Acquilty UPLC T3 column (2.1 mm × 100 mm, 1.7 µm). A triple quadrupole mass spectrometer, operating in positive and negative ionization modes, was used for multiple reaction monitoring to detect the 29 compounds. All calibration curves showed good linear regression (r2 > 0.998). RSDs of precision, reproducibility, and stability of active compounds were all lower than 5.0%. The recovery rates were 95.4-104.9%, with RSDs< 5.0%. This method was successfully used to analyze the samples, and the results showed that 26 representative active components from 8 herbs were detected in the granules. While aconitine, mesaconitine, and hypaconitine were not detected, indicating that the existing samples were safe. The granules had the maximum and minimum content of hesperidin (27.3 ± 0.375 mg/g) and benzoylaconine (38.2 ± 0.759 ng/g). To conclude, a fast, accurate, sensitive, and reliable HPLC-QQQ-MS/MS method was established, which can simultaneously detect 29 active compounds that have a considerable difference in the content of Fuzhengjiedu Granules. This study can be used to control the quality and safety of Fuzhengjiedu Granules and provide a basis and guarantee for further experimental research and clinical application.

C-terminal domain of mammalian complexin-1 localizes to highly curved membranes.

In presynaptic nerve terminals, complexin regulates spontaneous "mini" neurotransmitter release and activates Ca2+-triggered synchronized neurotransmitter release. We studied the role of the C-terminal domain of mammalian complexin in these processes using single-particle optical imaging and electrophysiology. The C-terminal domain is important for regulating spontaneous release in neuronal cultures and suppressing Ca2+-independent fusion in vitro, but it is not essential for evoked release in neuronal cultures and in vitro. This domain interacts with membranes in a curvature-dependent fashion similar to a previous study with worm complexin [Snead D, Wragg RT, Dittman JS, Eliezer D (2014) Membrane curvature sensing by the C-terminal domain of complexin. Nat Commun 5:4955]. The curvature-sensing value of the C-terminal domain is comparable to that of α-synuclein. Upon replacement of the C-terminal domain with membrane-localizing elements, preferential localization to the synaptic vesicle membrane, but not to the plasma membrane, results in suppression of spontaneous release in neurons. Membrane localization had no measurable effect on evoked postsynaptic currents of AMPA-type glutamate receptors, but mislocalization to the plasma membrane increases both the variability and the mean of the synchronous decay time constant of NMDA-type glutamate receptor evoked postsynaptic currents.