Synthesis and identification of novel oxa-steroids as progesterone receptor antagonists

A novel series of oxa-steroids 6 derived from (8S, 13S, 14R)-7-oxa-estra-4,9-diene-3,17-dione 1 have been synthesized and identified as potent and selective progesterone receptor antagonists. These novel oxa-steroids showed similar potency to mifepristone. Preliminary SAR study resulted in the most potent 17-phenylethynyl oxa-steroid 6i wih an IC(50) of 1.4nM. In contrast to the equipotent mifepristone toward the progesterone receptor (PR) and glucocorticoid receptor (GR), compound 6i had over 200-fold selectivity for PR over GR.     

Microbial community responses reduce soil carbon loss in Tibetan alpine grasslands under short‐term warming

Changes in labile carbon (LC) pools and microbial communities are the primary factors controlling soil heterotrophic respiration (R_h) in warming experiments. Warming is expected to initially increase R_h but studies show this increase may not be continuous or sustained. Specifically, LC and soil microbiome have been shown to contribute to the effect of extended warming on R_h. However, their relative contribution is unclear and this gap in knowledge causes considerable uncertainty in the prediction of carbon cycle feedbacks to climate change. In this study, we used a two‐step incubation approach to reveal the relative contribution of LC limitation and soil microbial community responses in attenuating the effect that extended warming has on R_h. Soil samples from three Tibetan ecosystems—an alpine meadow (AM), alpine steppe (AS), and desert steppe (DS)—were exposed to a temperature gradient of 5–25°C. After an initial incubation period, soils were processed in one of two methods: (a) soils were sterilized then inoculated with parent soil microbes to assess the LC limitation effects, while controlling for microbial community responses; or (b) soil microbes from the incubations were used to inoculate sterilized parent soils to assess the microbial community effects, while controlling for LC limitation. We found both LC limitation and microbial community responses led to significant declines in R_h by 37% and 30%, respectively, but their relative contributions were ecosystem specific. LC limitation alone caused a greater R_h decrease for DS soils than AMs or ASs. Our study demonstrates that soil carbon loss due to R_h in Tibetan alpine soils—especially in copiotrophic soils—will be weakened by microbial community responses under short‐term warming.     

Specific binding of integrin alphaIIbbeta3 to RGD peptide immobilized on a nitrilotriacetic acid chip: a surface plasmon resonance study

Nitrilotriacetic acid has been routinely used in protein purification for its high affinity for His-tagged protein in the presence of Ni²⁺. Here we reported a type of nitrilotriacetic acid chip (NTA-chip) prepared by transferring NTA-DOGS containing a lipid monolayer to a 50 nm thick gold layer deposited on a glass slide. The surface binding ability of His-tagged protein and regeneration of NTA chip were characterized using a synthetic polypeptide P1 (His-His-His-His-His-His--aminohexanoic-Gly-Gly-Arg-Gly-Asp-Ser). The effect of divalent cations on integrin binding affinity for RGD ligand was investigated after P1 had been immobilized onto the sensor chip. The results show that the NTA-chip is a useful tool to immobilize His-tagged protein on the chip surface, and can provide a functional orientation for further investigation. The results also show that removing of Ca²⁺ bound on low affinity sites or adding of Mn²⁺ can increase the binding ability of integrin.     

Genetic Diversity and Evolution of Bradyrhizobium Populations Nodulating Erythrophleum fordii,an Evergreen Tree Indigenous to the Southern Subtropical Region of China

The nodulation of Erythrophleum fordii has been recorded recently, but its microsymbionts have never been studied. To investigate the diversity and biogeography of rhizobia associated with this leguminous evergreen tree, root nodules were collected from the southern subtropical region of China. A total of 166 bacterial isolates were obtained from the nodules and characterized. In a PCR-based restriction fragment length polymorphism (RFLP) analysis of ribosomal intergenic sequences, the isolates were classified into 22 types within the genus Bradyrhizobium. Sequence analysis of 16S rRNA, ribosomal intergenic spacer (IGS), and the housekeeping genes recA and glnII classified the isolates into four groups: the Bradyrhizobium elkanii and Bradyrhizobium pachyrhizi groups, comprising the dominant symbionts, Bradyrhizobium yuanmingense, and an unclassified group comprising the minor symbionts. The nodC and nifH phylogenetic trees defined five or six lineages among the isolates, which was largely consistent with the definition of genomic species. The phylogenetic results and evolutionary analysis demonstrated that mutation and vertical transmission of genes were the principal processes for the divergent evolution of Bradyrhizobium species associated with E. fordii, while lateral transfer and recombination of housekeeping and symbiotic genes were rare. The distribution of the dominant rhizobial populations was affected by soil pH and effective phosphorus. This is the first report to characterize E. fordii rhizobia.     

MicroRNA-137 Is a Novel Hypoxia-responsive MicroRNA That Inhibits Mitophagy via Regulation of Two Mitophagy Receptors FUNDC1 and NIX

Mitophagy receptors mediate the selective recognition and targeting of damaged mitochondria by autophagosomes. The mechanism for the regulation of these receptors remains unknown. Here, we demonstrated that a novel hypoxia-responsive microRNA, microRNA-137 (miR-137), markedly inhibits mitochondrial degradation by autophagy without affecting global autophagy. miR-137 targets the expression of two mitophagy receptors NIX and FUNDC1. Impaired mitophagy in response to hypoxia caused by miR-137 is reversed by re-expression of FUNDC1 and NIX expression vectors lacking the miR-137 recognition sites at their 3′ UTR. Conversely, miR-137 also suppresses the mitophagy induced by fundc1 (CDS+3′UTR) but not fundc1 (CDS) overexpression. Finally, we found that miR-137 inhibits mitophagy by reducing the expression of the mitophagy receptor thereby leads to inadequate interaction between mitophagy receptor and LC3. Our results demonstrated the regulatory role of miRNA to mitophagy receptors and revealed a novel link between miR-137 and mitophagy.     

The preparation of ethylenediamine‐modified fluorescent carbon dots and their use in imaging of cells

In this work, fluorescent carbon dots (CDs) were synthesized using a hydrothermal method with glucose as the carbon source and were surface‐modified with ethylenediamine. The properties of as‐prepared CDs were analyzed by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), ultraviolet–visible light (UV/vis) absorption and fluorescent spectra. Furthermore, CDs conjugated with mouse anti‐(human carcinoembryonic antigen) (CEA) monoclonal antibody were successful employed in the biolabeling and fluorescent imaging of human gastric carcinoma cells. In addition, the cytotoxicity of CDs was also tested using human gastric carcinoma cells. There was no apparent cytotoxicity on human gastric carcinoma cells. These results suggest the potential application of the as‐prepared CDs in bioimaging and related fields. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemiluminescent determination of H2O2 using 4-(1,2,4-triazol-1-yl)phenol as an enhancer based on the immobilization of horseradish peroxidase onto magnetic beads

This article describes the employment of a novel p-phenol derivative, 4-(1,2,4-triazol-1-yl)phenol (TRP), as a highly potent signal enhancer of the luminol-hydrogen peroxide (H₂O₂)-horseradish peroxidase (HRP) chemiluminescence (CL) system. The CL reaction conditions were optimized, and the enhancement characteristics of TRP were compared with those of p-iodophenol (PIP). TRP produced a strong enhancement of the CL with the effect of prolonging the light emission. The developed system was then applied to the determination of H₂O₂ with immobilized HRP using magnetic beads as a solid support. The linear range for H₂O₂ was 2.0 × 10⁻⁶ to 1.0 × 10⁻³ M. The detection limit for H₂O₂ was 2.0 × 10⁻⁶ M. The proposed sensor was applied successfully to the determination of H₂O₂ in rainwater.     

Epidemiological,Clinical and Serological Characteristics of Children with Coronavirus Disease 2019 in Wuhan: A Single-centered,Retrospective Study

In December 2019, SARS-CoV-2 was first detected in the samples obtained from three adult patients who suffered from an unknown viral pneumonia in Wuhan (Li et al. 2020). This unknown viral pneumonia is further named as coronavirus disease 2019 (COVID-19) by the World Health Organization. To date, the number of new COVID-19 cases has continued to skyrocket and the impact of SARS-CoV-2 on humans is far greater than any pathogen of this century in both breadth and depth. Previous studies have shown that adults with COVID-19 have symptoms of fever, dry cough, dyspnea, fatigue and lymphocytopenia. Moreover, COVID-19 is more likely to cause death in the elderly, especially those with chronic comorbidities (Huang et al. 2020). In Wuhan, more than 50, 000 COVID-19 cases have been confirmed, including over 780 pediatric patients, and only one child death case (Lu et al. 2020). Although the number of children cases was far fewer than that of adults, COVID-19 might endanger children's health and the information on children remains limited, especially in serological study. In the retrospective study, the investigators analyzed the epidemiological, clinical and serological characteristics of children with COVID-19 in Wuhan in the early stages of the outbreak, which might provide theoretical and practical help in controlling COVID-19 and similar emerging infectious diseases in the future.     

Changes in bacterial communities during two agricultural solid wastes’ co-composting processes

Microbes perform an important role in the solid-state fermentation (SSF) process, and bacterial communities are more or less abundant depending on the starting materials and the composting procedure. In this study, high-throughput sequencing was used to investigate the changes in bacterial communities in different composting piles containing spent pig litter and distiller grains in five dry weight ratios, i.e., 100% distiller grains (treatment 1), 75% distillers grains/25% spent pig litter (treatment 2), 50% distillers grains/50% spent pig litter (treatment 3), 25% distillers grains/75% spent pig litter (treatment 4), and 100% spent pig litter (treatment 5). The results showed that the fermentation time of the thermophilic stage was prolonged with an appropriate content of distiller grains. The alpha-diversity analysis showed that the variation in bacterial richness and diversity in the various treatments (except treatment 5) was greater in the high-temperature stage than in the inception stage and then was slightly lower in the stabilization stage than in the thermophilic stage. The relative abundance of the predominant bacterial communities differed during different composting stages except in treatment 5. The abundant bacterial communities were similar among the treatments with different proportions of distiller grains (treatments 2, 3, and 4) during the high-temperature stage but differed during the stabilization stage, as increasing proportions of distiller grains increased the relative abundance of the phyla Proteobacteria and Firmicutes, and decreased that of Actinobacteria. Additionally, principal coordinate analysis (PCoA) showed that the bacterial communities in treatments 1, 2, 3, and 4 during the initial stage (day 0) were different from those observed during two other stages (day 10 and day 53), while treatment 5 showed only slight variations in the bacterial community structure in response to changes in the composting process. The results indicated that spent pig litter is not suitable for single-material composting and the addition of an appropriate amount of distiller grains can improve the fermentation process. The understanding of the microbial community diversity at molecular level provided a theoretical basis for the optimization of spent pig litter and/or distiller grain fermentation.     

SARS-CoV-2 envelope protein causes acute respiratory distress syndrome (ARDS)-like pathological damages and constitutes an antiviral target

Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology