中国被毛孢分生孢子形成过程显微结构的研究

分生孢子是中国被毛孢(H sinensis)生活史中极为重要的一个环节,其在冬虫夏草侵染和形成过程中有着十分关键的作用.本实验以中国被毛孢纯培养菌种为实验材料,采用显微镜观察了其菌丝体经营养生长产分生孢子过程中显微结构变化,结果表明:中国被毛孢在固体培养条件下,可以形成分生孢子,其形态和产生方式与微循环产孢过程中形成的分生孢子一致,同时,在产孢过程中,还存在瓶梗结构纵裂形成对生分生孢子的现象.     

Influence of Bio-Lubricants on the Tribological Properties of Ti6Al4V Alloy

Titanium alloy is one of the best materials for biomedical applications due to its superior biocompatibility, outstanding corrosion resistance, and low elastic modulus. However, the friction and wear behaviors of titanium alloys were sensitive to the environment including lubrication. In order to clarify the wear mechanism of titanium alloy under different lubrications including deionized water, physiological saline and bovine serum, the friction and wear tests were performed between Ti6Al4V plates and Si₃N₄ ball on a universal multi-functional tester. The friction and the wear rate of titanium alloy were measured under dry friction and three different lubrication conditions. The worn surfaces were examined by scanning electron microscopy. The results revealed that under the dry friction, the wear resistance of titanium alloy was the worst since the wear mechanism was mainly the combination of abrasive wear and oxidation wear. It was also found that Ti6Al4V alloy had low friction coefficient and wear rate under three lubrication conditions, and its wear mechanism was adhesive wear.     

铁还原菌降解石油烃的研究进展

铁还原菌是指能够利用细胞外Fe(III)作为末端电子受体,通过氧化有机物将Fe(III)还原为Fe(II)微生物的总称。铁还原作用广泛存在于土壤、河流、海洋、地表含水层以及高温高压的地下深部油藏。在厌氧或兼性厌氧条件下,Fe(III)还原耦合有机物的降解,对铁、碳元素的生物地球化学循环具有重要意义。本文介绍了铁还原菌的多样性和铁还原作用机理,综述了铁还原菌在石油烃降解方面的研究进展。此外,还总结了铁还原菌在生物修复中的潜在作用,并对未来的研究方向进行了展望。     

Relationship between myological variables and different take-off and landing behaviours in frogs

Although landing behaviour in anurans differs significantly among species, a take-off behaviour seems to be largely conserved in the evolution of frogs and toads. The ancestral mode of landing is hypothesized to involve the body crash-landing on the substrate, after which the anuran cycles the limbs forward and then backward to their resting position. The part of the body that first contacts the substrate may vary among taxa. The limbs and pectoral girdle muscles as well as those of the caudopelvic region, involved with landing and take-off behaviours, are investigated. The existence of a relationship exists between myology and different take-off and landing behaviours is explored. The results suggest that most of the muscles involved in both take-off and landing are conserved morphologically, with only few differing, depending on the locomotor behaviour. Two muscles tend to be longer; the m. coracobrachialis, which is involved with landing, and the m. coccygeosacralis, related to the take-off.     

Transition from Diffusion‐Controlled Intercalation into Extrinsically Pseudocapacitive Charge Storage of MoS2 by Nanoscale Heterostructuring

2D nanomaterials have been found to show surface‐dominant phenomena and understanding this behavior is crucial for establishing a relationship between a material's structure and its properties. Here, the transition of molybdenum disulfide (MoS₂) from a diffusion‐controlled intercalation to an emergent surface redox capacitive behavior is demonstrated. The ultrafast pseudocapacitive behavior of MoS₂ becomes more prominent when the layered MoS₂ is downscaled into nanometric sheets and hybridized with reduced graphene oxide (RGO). This extrinsic behavior of the 2D hybrid is promoted by the fast Faradaic charge‐transfer kinetics at the interface. The heterostructure of the 2D hybrid, as observed via high‐angle annular dark field–scanning transmission electron microscopy and Raman mapping, with a 1T MoS₂ phase at the interface and a 2H phase in the bulk is associated with the synergizing capacitive performance. This 1T phase is stabilized by the interactions with the RGO. These results provide fundamental insights into the surface effects of 2D hetero‐nanosheets on emergent electrochemical properties.     

Label-free quantitative proteomic analysis of the inhibitory activities of juglone against translation and energy metabolism in Escherichia coli

Plant-derived antimicrobial agents have received increasing attention owing to their potential to control pathogens and excellent efficacy despite the growing prevalence of antibiotic resistance. However, the antibacterial mechanism of juglone, a traditional medicine used to cure skin infections, is still unclear. Therefore, in this study, in order to elucidate the mechanisms underlying the antibacterial activity of juglone, label-free quantitative proteomic technology was applied for analysis of the 417 proteins that were differentially expressed in Escherichia coli after treatment with juglone at one-half of the minimum inhibitory concentration. Gene ontology enrichment analysis of differentially expressed proteins suggested that juglone effectively repressed the expression of dehydrogenase and cytochrome oxidase, indicating that energy generation was blocked. Additionally, juglone induced RNA formation and ribosome assembly, resulting in inhibition of translation. This is the first study to adopt a proteomic approach to investigate the antibacterial mechanism of action of juglone against E. coli.     

空肠弯曲杆菌生物膜形成和调控机理研究进展北大核心CSCD

空肠弯曲杆菌(Campylobacter jejuni)分泌胞外多糖和各种胞外蛋白和核酸等相互交联在一起构成生物膜,可增强其在不利环境下的生存率,尤其是对各种洗涤剂、抗生素和消毒剂的耐受力。本文从介质表面性质、温度、气体环境、以及基因的调控等多方面阐述了空肠弯曲杆菌生物膜结构及形成调控机制,同时对各种去除生物膜的实际应用做了分析和展望,为探寻生物膜的控制方法提供参考。     

Introducing an algal carbon‐concentrating mechanism into higher plants: location and incorporation of key components

Many eukaryotic green algae possess biophysical carbon‐concentrating mechanisms (CCMs) that enhance photosynthetic efficiency and thus permit high growth rates at low CO₂ concentrations. They are thus an attractive option for improving productivity in higher plants. In this study, the intracellular locations of ten CCM components in the unicellular green alga Chlamydomonas reinhardtii were confirmed. When expressed in tobacco, all of these components except chloroplastic carbonic anhydrases CAH3 and CAH6 had the same intracellular locations as in Chlamydomonas. CAH6 could be directed to the chloroplast by fusion to an Arabidopsis chloroplast transit peptide. Similarly, the putative inorganic carbon (Ci) transporter LCI1 was directed to the chloroplast from its native location on the plasma membrane. CCP1 and CCP2 proteins, putative Ci transporters previously reported to be in the chloroplast envelope, localized to mitochondria in both Chlamydomonas and tobacco, suggesting that the algal CCM model requires expansion to include a role for mitochondria. For the Ci transporters LCIA and HLA3, membrane location and Ci transport capacity were confirmed by heterologous expression and H¹⁴CO₃^‐ uptake assays in Xenopus oocytes. Both were expressed in Arabidopsis resulting in growth comparable with that of wild‐type plants. We conclude that CCM components from Chlamydomonas can be expressed both transiently (in tobacco) and stably (in Arabidopsis) and retargeted to appropriate locations in higher plant cells. As expression of individual Ci transporters did not enhance Arabidopsis growth, stacking of further CCM components will probably be required to achieve a significant increase in photosynthetic efficiency in this species.     

间充质干细胞治疗糖尿病心脏病研究进展及其机制

糖尿病心脏病(diabetic cardiomyopathy,DCM)患者心脏病变弥漫、病变程度严重,患病率与死亡率逐年上升,缺乏有效的治疗手段,找到其他的治疗途径已成为一项重要内容。有研究发现,间充质干细胞(mesenchymal stem cells,MSCs)作为一种具有多分化潜能的细胞,能够通过多种机制作用于DCM的病理改变,提高心脏射血分数、改善心室重塑,是一种富有前景的治疗手段,本文着重就DCM的发病机制、MSCs对DCM的治疗机制及效果做一综述,为MSCs在DCM治疗中的应用提供重要的临床前实验依据。