Five New Phenolic Glycosides from Viburnum luzonicum

Viburnum luzonicum is widely distributed in China. Its branch extracts showed potential α-amylase and α-glucosidase inhibitory activities. In order to discover new bioactive constituents, five undescribed phenolic glycosides, viburozosides A−E ( 1 – 5 ), were obtained by bioassay-guided isolation coupled with HPLC-QTOF-MS/MS analysis. Their structures were elucidated by spectroscopic analyses, including 1D NMR, 2D NMR, ECD, and ORD. All compounds were tested for their α-amylase and α-glucosidase inhibitory potency. Compound 1 showed significantly competitive inhibition against α-amylase (IC₅₀=17.5 μM) and α-glucosidase (IC₅₀=13.6 μM).     

Circular RNA SLTM as a miR-421-competing endogenous RNA to mediate HMGB2 expression stimulates apoptosis and inflammation in arthritic chondrocytes

Osteoarthritis (OA) is the most common age-related joint disease characterized by chronic inflammation, progressive articular cartilage destruction, and subchondral sclerosis. Accumulating evidence suggests that circular RNAs (circRNAs) play key roles in OA, but the function of circSLTM in OA remains greatly unknown. Therefore, this study focused on interleukin-1β (IL-1β)-treated primary human chondrocytes as well as a rat model to investigate the expression pattern and functional role of circSLTM in OA in vitro and in vivo. CircSLTM and high mobility group protein B2 (HMGB2) were upregulated in IL-1β-induced chondrocytes, whereas miR-421 was downregulated. Knockdown of circSLTM or overexpression of miR-421 ameliorated IL-1β-induced chondrocyte apoptosis and inflammation. The regulatory relationship between circSLTM and miR-421, as well as that between miR-421 and HMGB2, was predicted by bioinformatics and then verified by the RNA immunoprecipitation experiment and dual-luciferase reporter gene assay. Furthermore, silencing of circSLTM increased cartilage destruction and decreased cartilage tissue apoptosis rate and inflammation in a rat model of OA. Taken together, our findings demonstrate the fundamental role of circSLTM in OA progression and provide a potential molecular target for OA therapy.     

Understanding the Impact of Oligomeric Polystyrene Side Chain Arrangement on the All‐Polymer Solar Cell Performance

The introduction of oligomeric polystyrene (PS) side chains into the conjugated backbone is proven to enhance the processability and electronic properties of semiconducting polymers. Here, two series of donor and acceptor polymers are prepared with different molar percentages of PS side chains to elucidate the effect of their substitution arrangement on the all‐polymer solar cell performance. The observed device performance is lower when the PS side chains are substituted on the donor polymer and higher when on the acceptor polymer, indicating a clear arrangement effect of the PS side chain. The incorporation of PS side chains to the acceptor polymer contributes to the decrease in phase separation domain size in the blend films. However, the reduced domain size was still an order of magnitude larger than the typical exciton diffusion length. A detailed morphological study together with the estimation of solubility parameter of the pristine PS, donor, and acceptor polymers reveals that the relative value of solubility parameter of each component dominantly contributes to the purity of the phase separated domain, which strongly impacts the amount of generated photocurrent and overall solar cell performance. This study provides an understanding of the design strategies to improve the all‐polymer solar cells.     

N2O and CH4 Emissions,and NO3 − Leaching on a Crop-Yield Basis from a Subtropical Rain-fed Wheat–Maize Rotation in Response to Different Types of Nitrogen Fertilizer

Guaranteeing high crop yields while reducing environmental impacts of nitrogen fertilizer use due to associated losses of N₂O emissions and nitrate (NO₃ ^?) leaching is a key challenge in the context of sustainable intensification of crop production. However, few field data sets are available that explore the effect of different forms of N management on yields as well as on N losses in the form of N₂O or NO₃ ^?. Here we report on a large-scale field lysimeter (8 × 4 m²) experiment, which was designed to determine soil CH₄ and N₂O emissions, NO₃ ^? leaching losses and crop yields from a subtropical rain-fed wheat–maize rotation in the Sichuan Basin, one of the most intensively used agricultural regions in China. One control and three different fertilizer treatments with the same total rate of N application (280 kg N ha^?1 y^?1) were included: NF: control (no fertilizer); NPK: synthetic N fertilizer; OMNPK: synthetic N fertilizer plus pig manure; RSDNPK: synthetic N fertilizer plus crop residues. As compared to the standard NPK treatment, annual NO₃ ^? leaching losses for OMNPK and RSDNPK treatments were decreased by 36 and 22%, respectively (P < 0.05). Similarly, crop yield-scaled NO₃ ^? leaching for NPK treatment was higher than those for either OMNPK or RSDNPK treatments (P < 0.05). Direct N₂O emissions for RSDNPK treatment were decreased as compared with NPK and OMNPK treatments (P < 0.05). Furthermore, the yield-scaled GWP (global warming potential) was lower for the treatments where either pig manure or crop residues were incorporated as compared to the standard NPK treatment (P < 0.05). Our study indicates that it is possible to reduce the negative environmental impact of NO₃ ^? leaching and N₂O emissions without compromising crop productivity. Yield-scaled NO₃ ^? leaching, similar to the yield-scaled GWP, represents another valuable-integrated metric to address the dual goals of reducing nitrogen pollution and maintaining crop grain yield for a given agricultural system.     

3-hydroxyisobutyrate dehydrogenase-I from Pseudomonas denitrificans ATCC 13867 degrades 3-hydroxypropionic acid

This study examined the role and physiological relevance of 3-hydroxyisobutyrate dehydrogenase-I (3HIBDHI) of Pseudomonas denitrificans ATCC 13867 in the degradation of 3-hydroxypropionic acid (3-HP) during 3-HP production. The gene encoding 3HIBDH-I of P. denitrificans ATCC 13867 was cloned and expressed in Escherichia coli BL21 (DE3). The recombinant 3HIBDH-I was then purified on a Ni-NTA-HP column and characterized for its choice of substrates, cofactors, metals, reductants, and the optimal temperature and pH. The recombinant 3HIBDH-I showed a high catalytic constant (k _cat/K _m) of 604.1 ± 71.1 mM/S on (S)-3-hydroxyisobutyrate, but no detectable activity on (R)-3-hydroxyisobutyrate. 3HIBDH-I preferred NAD⁺ over NADP⁺ as a cofactor for its catalytic activity. The k _cat/K _m determined for 3-HP was 15.40 ± 1.43 mM/S in the presence of NAD⁺ at 37°C and pH 9.0. In addition to (S)-3-hydroxyisobutyrate and 3-HP, 3HIBDH-I utilized l-serine, methyl-d,l-serine, and methyl-(S)-(+)-3-hydroxy-2-methylpropionate; on the other hand, the k _cat/K _m values determined for these substrates were less than 5.0mM/S. Ethylenediaminetetraacetic acid, 2-mercaptoethanol, dithiothreitol and Mn²⁺ increased the activity of 3HIBDHI significantly, whereas the presence of Fe²⁺, Hg²⁺ and Ag⁺ in the reaction mixture at 1.0 mM completely inhibited its activity. This study revealed the characteristics of 3HIBDH-I and its significance in 3-HP degradation.     

The Roles of p38 MAPK/MSK1 Signaling Pathway in the Neuroprotection of Hypoxic Postconditioning Against Transient Global Cerebral Ischemia in Adult Rats

Postconditioning has regenerated interest as a mechanical intervention against cerebral ischemia/reperfusion injury, but its molecular mechanisms remain unknown. We previously reported that hypoxic postconditioning (HPC) ameliorated neuronal death induced by transient global cerebral ischemia (tGCI) in hippocampal CA1 subregion of adult rats. This study tested the hypothesis that p38-mitogen-activated protein kinase (p38 MAPK)/mitogen- and stress-response kinase 1 (MSK1) signaling pathway plays a role in the HPC-induced neuroprotection. Male Wistar rats were subjected to 10 min ischemia induced by applying the four-vessel occlusion method. HPC with 120 min was applied at 24 h after reperfusion. Immunohistochemistry and Western blot were used to detect the expression of phosphorylation of p38 MAPK and MSK1, as well as cleaved caspase-3. We found that HPC induced a significant increase of phosphorylated p38 MAPK and MSK1 in neurons of hippocampal CA1 region and a significant decrease in glial cells after tGCI as well. Furthermore, HPC attenuated caspase-3 cleavation triggered by tGCI in CA1 region. Moreover, p38 MAPK inhibition by SB203580 significantly decreased the phosphorylation of MSK1, increased cleaved caspase-3 expression, and abolished the neuroprotection of HPC. These findings suggested that p38 MAPK/MSK1 signaling axis contributed to HPC-mediated neuroprotection against tGCI, at least in part, by regulating the activation of caspase-3.     

海南凤仙花不同海拔种群的传粉生物学

凤仙花属(Impatiens)植物具有极为广泛的多样性和类型各异的特化传粉者, 被誉为“双子叶的兰花”, 受到众多传粉生物学家的关注。本文以海南特有种海南凤仙花(Impatiens hainanensis)为研究对象, 对3个不同海拔梯度的种群进行了开花生物学特性和开花物候、花器官结构、花粉活力和柱头活性、传粉者种类和访花行为及繁育系统的比较研究。结果表明: 单花花期4.10 ± 0.46 d, 雄性期和雌性期分别约为3.15 ± 0.24 d和0.95 ± 0.36 d; 种群开花峰期在8月初, 高海拔种群的花期高峰相对滞后。低、中海拔种群花粉活力呈现先升高后下降的趋势, 以开花第2 d花粉活力最高; 高海拔种群花粉活力随开花时间推移逐渐下降; 柱头活性随开花时间的推移而增强, 高海拔种群开花各天次均较低、中海拔种群低。主要传粉昆虫为黄黑无垫蜂(Amegilla leptocoma)和绿条无垫蜂(A. zonata), 低、中海拔种群以黄黑无垫蜂为主, 高海拔种群以绿条无垫蜂为主。未观察到自动自花授粉和无融合生殖现象, 人工授粉能明显增加坐果率(75-90%), 自然坐果率在高海拔种群相对较低(40-60%), 说明存在较强的传粉者限制。海南凤仙花的保护需要同时关注其有效传粉者的保护, 促进有效传粉昆虫在不同海拔种群之间的往来, 保证种群间的花粉流与种子流, 维持海南凤仙花的种群遗传多样性与有效种群大小。     

Polyethyleneimine-coating enhances adenoviral transduction of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are non-hematopoietic cells with multi-lineage potential, which makes them attractive targets for regenerative medicine applications. Efficient gene transfer into MSCs is essential for basic research in developmental biology and for therapeutic applications involving gene-modification in regenerative medicine. Adenovirus vectors (Advs) can efficiently and transiently introduce an exogenous gene into many cell types via their primary receptors, the coxsackievirus and adenovirus receptors (CARs), but not into MSCs, which lack CAR expression. To overcome this problem, an Adv coated with cationic polymer polyethyleneimine (PEI) was developed. In this study, we demonstrated that PEI coating with an optimal ratio can enhance adenoviral transduction of MSCs without cytotoxicity. We also investigated the physicochemical properties and internalization mechanisms of the PEI-coated Adv. These results could help to evaluate the potentiality of the PEI-coated Adv as a prototype vector for efficient and safe transduction into MSCs.     

miR824-Regulated AGAMOUS-LIKE16 Contributes to Flowering Time Repression in Arabidopsis

The timing of flowering is pivotal for maximizing reproductive success under fluctuating environmental conditions. Flowering time is tightly controlled by complex genetic networks that integrate endogenous and exogenous cues, such as light, temperature, photoperiod, and hormones. Here, we show that AGAMOUS-LIKE16 (AGL16) and its negative regulator microRNA824 (miR824) control flowering time in Arabidopsis thaliana. Knockout of AGL16 effectively accelerates flowering in nonvernalized Col-FRI, in which the floral inhibitor FLOWERING LOCUS C (FLC) is strongly expressed, but shows no effect if plants are vernalized or grown in short days. Alteration of AGL16 expression levels by manipulating miR824 abundance influences the timing of flowering quantitatively, depending on the expression level and number of functional FLC alleles. The effect of AGL16 is fully dependent on the presence of FLOWERING LOCUS T (FT). Further experiments show that AGL16 can interact directly with SHORT VEGETATIVE PHASE and indirectly with FLC, two proteins that form a complex to repress expression of FT. Our data reveal that miR824 and AGL16 modulate the extent of flowering time repression in a long-day photoperiod.     

基因工程链激酶(r—SK)纯化及其单克隆抗体制备和鉴定

采用Rotofor等电聚焦和分子筛技术纯化大肠杆菌表达的重组链激酶(r—SK),其纯度为97%。比活性1×10⁶IU／mg,回收率41％。分析所纯化的r—SK　N端氨基酸顺序证实其1—15个氨基酸顺序与SK基因的核苷酸顺序所示3联密码子一致。以纯化r—SK为抗原,通过杂交瘤技术构建了分泌抗r—SK单克隆抗体(McAb)杂交瘤细胞(4D11),该McAb属IgG1亚型．特异地作用于r-SK和C组口溶血性链球菌分泌的SK。用底物显色法测定该McAb可抑制SK对纤溶酶原的激活。Western blot法证实该McAb能识别分子量为16 250Da的r—SK的CNBr裂解片段。推测SK蛋白中第71残基至第237残基间的氨基酸顺序参与SK与纤溶酶原的结合。