Biological characteristics of manganese transporter MntP in Klebsiella pneumoniae.

Klebsiella pneumoniae is an important opportunistic pathogen that causes a variety of infections. It is critical for bacteria to maintain metal homeostasis during infection. By using an isogenic mntP deletion mutant of K. pneumoniae strain NTUH-K2044, we found that MntP was a manganese efflux pump. Manganese increased the tolerance to oxidative stress, and oxidative stress could increase the intracellular manganese concentration. In oxidative stress, the mntP deletion mutant exhibited significantly higher sensitivity to manganese. Furthermore, iron could increase the tolerance of the mntP deletion mutant to manganese. Inductively coupled plasma mass spectrometry analysis revealed that the mntP deletion mutant had higher intracellular manganese and iron concentrations than wild-type and complementary strains. These findings suggested that iron could increase manganese tolerance in K. pneumoniae. This work elucidated the role of MntP in manganese detoxification and Mn/Fe homeostasis in K. pneumoniae.IMPORTANCEMetal homeostasis plays an important role during the process of bacterial infection. Herein, we revealed that MntP was involved in intracellular manganese homeostasis. Manganese promoted resistance to oxidative stress in Klebsiella pneumoniae. Furthermore, we demonstrated that the mntP deletion mutant exhibited significantly lower survival under manganese and H2O2 conditions. Oxidative stress increased the intracellular manganese content of the mntP deletion mutant. MntP played a critical role in maintaining intracellular manganese and iron concentrations. MntP contributed to manganese detoxification and Mn/Fe homeostasis in K. pneumoniae.

GPR30 selective agonist G-1 induced insulin resistance in ovariectomized mice on high fat diet and its mechanism.

BACKGROUND: Previous in vivo and in vitro studies have demonstrated that estrogen receptor agonist G-1 regulates glucose and lipid metabolism. This study focused on the effects of G-1 on cardiometabolic syndrome and anti-obesity under a high fat diet (HFD). METHODS: Bilateral ovariectomized female mice were fed an HFD for 6 weeks, and treated them with G-1. A cardiomyocyte insulin resistance model was used to simulate the in vivo environment. The main outcome measures were blood glucose, body weight, and serum insulin levels to assess insulin resistance, while cardiac function and degree of fibrosis were assessed by cardiac ultrasound and pathological observations. We also examined the expression of p-AMPK, p-AKT, and GLUT4 in mice hearts and in vitro models to explore the mechanism by which G-1 regulates insulin signaling. RESULTS: G-1 reduced body weight in mice on an HFD, but simultaneously increased blood glucose and promoted insulin resistance, resulting in myocardial damage. This damage included disordered cardiomyocytes, massive accumulation of glycogen, extensive fibrosis of the heart, and thickening of the front and rear walls of the left ventricle. At the molecular level, G-1 enhances gluconeogenesis and promotes glucose production by increasing the activity of pyruvate carboxylase (PC) while inhibiting GLUT4 translocation via the AMPK/TBC1D1 pathway, thereby limiting glucose uptake. CONCLUSION: Despite G-1's the potential efficacy in weight reduction, the concomitant induction of insulin resistance and cardiac impairment in conjunction with an HFD raises significant concerns. Therefore, comprehensive studies of its safety profile and effects under specific conditions are essential prior to clinical use.

[Niche of the mosses on floor in Shanghai City].

The mosses on the floor of 22 sites at 20 main parks and 2 chemical plants in Shanghai were sampled, and 75 moss species were recorded. Their niche breadths were calculated by Levins equation. The results indicated that most moss species had rather narrow niche breadth, 68% of them with a niche breadth less than 0.1. The relationship between species number (N) and their niche breadth (B) followed the model N = 0.344 x e(-0.0377B), R = 0.9684. The niche overlaps of 39 main moss species (important value > 0.1) were calculated by Wang's equation. Based on their niche overlaps, the ordination plot of Principal Axes Analysis (PAA) and the Minimal Spanning Tree (MST) were drawn. The results showed that five ecological groups of the 39 moss species related to different habitats could be identified.

[Distribution patterns of moss species in Shanghai city].

The mosses on the floor of 22 sites at 20 main parks and 2 chemical plants in Shanghai city were investigated and sampled. Based on 75 recorded moss species and their coverage, Two-way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA) were used to analyze their distribution patterns. The results showed that the study sites could be identified as three groups. Group 1 included two chemical plants and two parks at the center of the city, with 23 moss species and the smallest total coverage of 21.29%; group 2 included part of the parks at the center of the city and surrounding areas, with 44 moss species and total coverage of 37.94%; and group 3 mainly included the parks at surrounding areas and suburbs of the city, with 49 moss species and total coverage of 49.66%. The results reflected a certain correlation of the distribution of moss species with different habitats and polluted and disturbed environments in the city.