The presence of serotonin in cigarette smoke – a possible mechanistic link to 5-HT-induced airway inflammation

We previously reported the involvement of serotonin (5-HT) metabolism in cigarette smoke-induced oxidative stress in rat lung in vivo. Here, we report cigarette smoke as a source of serotonin (5-HT) to the airways and aim at investigating the effects of 5-HT on oxidative stress and inflammation in human bronchial epithelial cells (BEAS-2B). A 5-HT analog was identified to be present in aqueous phase cigarette smoke using the LC-MS/MS approach, which was later confirmed by a 5-HT enzyme-linked immune assay (EIA). Furthermore, exposure to 5-HT caused a time-dependent elevation of intracellular ROS level, which was blocked in the presence of apocynin (a NOX inhibitor). In support, the immunoblot analysis indicated that there was an increase in the expression of NOX2 time-dependently. 5-HT-induced elevation of IL-8 at both mRNA and protein levels was observed, which was inhibited by TEMPOL (a free radical scavenger), and inhibitors for p38 MAPK (SB203580) and ERK (U0126), in line with the time-dependent phosphorylation of p38 MAPK and ERK. In conclusion, our findings suggest that 5-HT presented in bronchial epithelium of smokers may be involved in cigarette smoke-induced oxidative stress and inflammation via activation of p38 MAPK and ERK pathway after the formation of free radicals.     

氯代脱氧松三糖的合成

本文报道由天然植物提取的松三糖为原料,在三苯基膦-四氯化碳体系进行氯代反应.结果发现氯代只发生在伯羟基上,且有较高选择性.经元素分析、IR、H-NMR、~（13）C-NMR、FAB-MS谱测定了产物结构;并通过分子模型计算作了解释.     

Inhibition of ubiquitin-specific protease 13-mediated degradation of Raf1 kinase by Spautin-1 has opposing effects in naïve and primed pluripotent stem cells

Embryonic stem cells (ESCs) are progenitor cells that retain the ability to differentiate into various cell types and are necessary for tissue repair. Improving cell culture conditions to maintain the pluripotency of ESCs in vitro is an urgent problem in the field of regenerative medicine. Here, we reveal that Spautin-1, a specific small-molecule inhibitor of ubiquitin-specific protease (USP) family members USP10 and USP13, promotes the maintenance of self-renewal and pluripotency of mouse ESCs in vitro. Functional studies reveal that only knockdown of USP13, but not USP10, is capable of mimicking the function of Spautin-1. Mechanistically, we demonstrate that USP13 physically interacts with, deubiquitinates, and stabilizes serine/threonine kinase Raf1 and thereby sustains Raf1 protein at the posttranslational level to activate the FGF/MEK/ERK prodifferentiation signaling pathway in naïve mouse ESCs. In contrast, in primed mouse epiblast stem cells and human induced pluripotent stem cells, the addition of Spautin-1 had an inhibitory effect on Raf1 levels, but USP13 overexpression promoted self-renewal. The addition of an MEK inhibitor impaired the effect of USP13 upregulation in these cells. These findings provide new insights into the regulatory network of naïve and primed pluripotency.     

Higher accumulation capacity of cadmium than zinc by <Emphasis Type="Italic">Arabidopsis halleri ssp. germmifera</Emphasis> in the field using different sowing strategies

Background and Aims

Litter decomposition serves an important role in maintaining nitrogen (N) availability within forest ecosystems. However, the interactive effects of exogenous N, drought, and litter quality and mixing on N immobilization during decomposition remain unclear. The aim of this study was to assess the effects of litter quality, reduced precipitation, N addition, and their interactions on litter mass loss and N immobilization.

Methods

This field study analyzed the effects of N addition and decreased precipitation on the decomposition rates and associated N immobilization of four types of litter: Quercus mongolica (QM), Tilia amurensis (TA), Pinus koraiensis (PK), and a mixture (MIX) of all three. The chemical quality of the MIX was prepared in a 4:3:3 (mass) ratio of PK, TA, and QM litters. Litterbags were placed in an N addition and precipitation manipulation forest field and collected after 92, 154, 365, 457, and 874 days. Decomposing litter residues were characterized for mass loss and N content to assess N immobilization.

Results

The addition of N had no significant effect on litter decomposition under both precipitation conditions, but a reduction in precipitation significantly depressed litter decomposition. The increases in N immobilization with N addition depended on the litter type and decomposition period. Precipitation reduction had significant effects on N immobilization and enhanced the magnitude and duration of N immobilization in decomposing litter, and both of which can be increased by N addition. The results indicate that the litter species is the major regulator that controls mass loss and N immobilization. Furthermore, the MIX treatment did not show non-additive effects on mass loss but did exhibit some weak synergistic effects on N immobilization.

Conclusions

Our results suggest that decomposing litters could help to sequester N depending on the litter identity and water regime in temperate forest ecosystems.

     

Mesenchymal stromal cells ameliorate acute allergic rhinitis in rats

Mesenchymal stromal cells (MSCs) have been extensively investigated as a potential antiinflammatory treatment in many inflammatory‐related diseases; however, it remains unclear whether MSCs could be used to treat acute allergic rhinitis. A rat model of allergic rhinitis was treated with MSCs. The effect of MSCs on the inflammation of allergic rhinitis was evaluated by sneezing, nose rubbing, the pathology of the nasal mucosa, and the expression of interleukin 4, tumour necrosis factor alpha, and immunoglobulin E in the serum of rats. Also, the population of MSCs isolated from umbilical cords of humans was evaluated to determine if they could inhibit the symptoms and inflammation of acute allergic rhinitis in a rat model. We observed that this population of cells inhibited sneezing, nose rubbing, and changes in the pathology of the nasal mucosa. Intriguingly, we observed that MSCs reduced the expression of interleukin 4, tumour necrosis factor alpha, and immunoglobulin E in the serum. Furthermore, MSCs reduced the expression of histamine and the recruitment of macrophages in the nasal mucosa of allergic rhinitis rats. We reasoned that the effect of MSCs on allergic rhinitis might be through its regulation of the secretion of related cytokines from macrophages during the process of acute allergic rhinitis. This work suggested that MSCs from the umbilical cords of humans could be used as a positive clinical therapy for the human disease.     

插入序列共同区元件：细菌中新出现的一种基因捕获系统

摘要：插入序列共同区（Insertion sequence common region,ISCR）元件是一类在结构和功能上与IS91家族相似的特殊插入序列,特点是缺少了末端反向重复序列（Inverted repeats, IRs）,在插入位点不产生直接重复序列,并通过滚环式（Rolling circle, RC）进行转座。ISCR元件作为一种新的基因捕获系统,它可以移动邻近的任何DNA序列,为耐药基因在不同种属细菌间水平传播提供了高效的媒介。世界各地多种革兰氏阴性病原菌中已发现有19种ISCR元件,大部分ISCR元件同时携带了多种耐药基因,提示ISCR有可能会造成细菌多重耐药性的快速传播。本文就ISCR结构特征、类型、移动方式、起源及进化的研究进展进行了综述。     

Rapid Evolution of Simple Sequence Repeat Induced by Allopolyploidization

Microsatellite evolution normally occurs in diploids. Until now, there has been a lack of direct experimental evidence for microsatellite evolution following allopolyploidization. In the present study, F₁ hybrids and newly synthesized allopolyploids were derived from Triticum aestivum Chinese Spring × Secale cereale Jinzhou-heimai. One hundred and sixty-three wheat simple sequence repeat (SSR) markers were used to investigate the variation of wheat microsatellites after allopolyploidization and variation of the PCR products of 29 of the SSR markers was observed. Of these 29 SSR markers, 15 were unable to produce products from amphiploids. The other 14 SSR markers did produce products from parental wheat, F₁ hybrids and amphiploids. However, the length of the products amplified from amphiploids was different from the length of the products amplified from parental wheat and F₁ hybrids. Sequencing indicated that the length variation of the 14 microsatellites stemmed mainly from variation in the number of repeat units. The alteration of repeat units occurred in both perfect and compound repeats. In some compound SSR loci, one motif was observed to expand whereas another to contract. Almost all the microsatellite evolution observed in this study could be explained by the slipped-strand mispairing model. The results of this study seem to indicate that stress caused by allopolyploidization might be one of the factors that induce microsatellite evolution. In addition, the findings of present study provided an instance of how simple sequence repeats evolved after allopolyploidization.