Synapse maturation and structural plasticity at Drosophila neuromuscular junctions

The Drosophila larval neuromuscular junction has recently emerged as a powerful model system to characterize the cellular and molecular events involved in the formation and flexibility of synapses. The combination of molecular, genetic, electrophysiological and anatomical approaches has revealed, for example, the functional significance of the discs-large gene product (a novel synapse-organizing protein) in the nervous system. This protein is involved in the clustering of at least one ion channel and in the structural modification of glutamatergic synapses during target muscle growth. The manipulation of the genes encoding ion channels, components of second-messenger cascades, and cell adhesion molecules is beginning to tease apart the mechanisms underlying structural synaptic plasticity.     

SAPl8和Sufu蛋白质复合物的表达纯化研究

通过分子克隆技术将Sufu和SAP18构建到原核载体,在原核表达系统进行外源表达,采用亲和层析和分子筛层析对Sufu和SAPl8及其复合物进行纯化。同时利用非变性胶的方法进一步确定该蛋白之间的相互作用及结合比例。结果表明,原核表达系统中Sufu和SAPl8蛋白表达量高,可以纯化到高纯度的蛋白质。su如和SAPl8结合的摩尔比为1：1,按摩尔比1：2混合、纯化可以得到高纯度、稳定的蛋白复合物,从而为进一步复合物的结构生物学研究奠定基础。     

Biotechnological challenges of bioartificial kidney engineering

With the world-wide increase of patients with renal failure, the development of functional renal replacement therapies have gained significant interest and novel technologies are rapidly evolving. Currently used renal replacement therapies insufficiently remove accumulating waste products, resulting in the uremic syndrome. A more preferred treatment option is kidney transplantation, but the shortage of donor organs and the increasing number of patients waiting for a transplant warrant the development of novel technologies. The bioartificial kidney (BAK) is such promising biotechnological approach to replace essential renal functions together with the active secretion of waste products. The development of the BAK requires a multidisciplinary approach and evolves at the intersection of regenerative medicine and renal replacement therapy. Here we provide a concise review embracing a compact historical overview of bioartificial kidney development and highlighting the current state-of-the-art, including implementation of living-membranes and the relevance of extracellular matrices. We focus further on the choice of relevant renal epithelial cell lines versus the use of stem cells and co-cultures that need to be implemented in a suitable device. Moreover, the future of the BAK in regenerative nephrology is discussed.     

Medicago truncatula stress associated protein 1 gene (MtSAP1) overexpression confers tolerance to abiotic stress and impacts proline accumulation in transgenic tobacco

Stress associated proteins (SAP) have been already reported to play a role in tolerance acquisition of some abiotic stresses. In the present study, the role of MtSAP1 (Medicago truncatula) in tolerance to temperature, osmotic and salt stresses has been studied in tobacco transgenic seedlings. Compared to wild type, MtSAP1 overexpressors were less affected in their growth and development under all tested stress conditions. These results confirm that MtSAP1 is involved in the response processes to various abiotic constraints. In parallel, we have performed studies on an eventual link between MtSAP1 overexpression and proline, a major player in stress response. In an interesting way, the results for the transgenic lines did not show any increase of proline content under osmotic and salt stress, contrary to the WT which usually accumulated proline in response to stress. These data strongly suggest that MtSAP1 is not involved in signaling pathway responsible for the proline accumulation in stress conditions. This could be due to the fact that the overexpression of MtSAP1 provides sufficient tolerance to seedlings to cope with stress without requiring the free proline action. Beyond that, the processes by which the MtSAP1 overexpression lead to the suppression of proline accumulation will be discussed in relation with data from our previous study involving nitric oxide.     

白花蛇舌草醇提取物对乳腺癌T-47D细胞株生长的抑制作用

目的：观察白花蛇舌草醇提取物对乳腺癌细胞T-47D生长的影响。方法：采用平皿克隆形成实验、软琼脂集落形成实验和BrdUrd（溴脱氧尿苷）掺入实验,观察不同浓度的白花蛇舌草醇提取物（1.0μg/mL,3.0μg/mL,10μg/mL,30μg/mL,100μg/mL）对T-47D细胞锚定依赖性生长和软琼脂集落形成能力及核酸合成的抑制作用。结果：①随着白花蛇舌草醇提取物浓度的升高,对T-47D细胞的生长呈现明显抑制作用;②白花蛇舌草醇提取物可呈浓度依赖性抑制对数生长期T-47D细胞核酸合成。结论：白花蛇舌草醇提取物可能通过影响肿瘤细胞核酸合成而抑制T-47D细胞生长。     

B Cell Diversification Is Uncoupled from SAP-Mediated Selection Forces in Chronic Germinal Centers within Peyer’s Patches

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Modeling Biological Membranes with Circuit Boards and Measuring Electrical Signals in Axons: Student Laboratory Exercises

This is a demonstration of how electrical models can be used to characterize biological membranes. This exercise also introduces biophysical terminology used in electrophysiology. The same equipment is used in the membrane model as on live preparations. Some properties of an isolated nerve cord are investigated: nerve action potentials, recruitment of neurons, and responsiveness of the nerve cord to environmental factors.     

Conformational changes in p47 upon activation highlighted by mass spectrometry coupled to hydrogen/deuterium exchange and limited proteolysis

The neutrophil NADPH oxidase is an enzymatic complex involved in innate immunity. Phosphorylation of p47^phox promotes its translocation with p67^phox and p40^phox, followed by membrane interaction and assembly with flavocytochrome b₅₅₈ into a functional complex. To characterise p47^phox conformational changes during activation, we used wild-type and the S303/304/328E triple mutant mimicking the phosphorylated state. Hydrogen/deuterium exchange and limited proteolysis coupled to mass spectrometry were used to discriminate between the various structural models. An increase in deuteration confirmed that p47^phox adopts an open and more flexible conformation after activation. Limited proteolysis correlated this change with increased auto-inhibitory region (AIR) accessibility. These results establish a structural link between the AIR release and the exposure of the Phox homology (PX) domain.