Mass production of medium-chain-length poly(3-hydroxyalkanoates) from hydrolyzed corn oil by fed-batch culture of Pseudomonas putida

A novel biopolyester, Medium-Chain-Length Polyhydroxyalkanoates (MCL-PHAs), was made from the corn oil hydrolysate, an inexpensive and renewable carbon source, by a fed-batch culture of Pseudomonas putida with a phosphate limitation. The cell growth, MCL-PHAs accumulation and feeding strategies of corn oil hydrolysate in the cultures of P. putida were investigated in 5 l and 30 l fermentors respectively. In the optimal fermentation, the final cell and MCL-PHAs concentrations reached 103 and 28 g/l, which represents a MCL-PHAs productivity of 0.61 g/l h. It was confirmed by its NMR spectrum that this MCL-PHAs from corn oil hydrolysate contained 4 saturated and 3 unsaturated monomers with a chain length of 6–14 carbon atoms.     

Penetration of verapamil across blood brain barrier following cerebral ischemia depending on both paracellular pathway and P-glycoprotein transportation

Background

Blood brain barrier (BBB) dysfunction is a common facet of cerebral ischemia, and the alteration of drug transporter, P-glycoprotein (P-gp), has been documented.

Aims

This study explores influence of damaged BBB and elevated P-gp on cerebral verapamil penetration after ischemia both in vivo and in vitro.

Methods

Middle cerebral artery occlusion (MCAO) induced ischemia/reperfusion (I/R) of rats, and Na₂S₂O₄ induced hypoxia/reoxygenation (H/R) damage of rat brain mirovessel endothelial cells (RBMECs) respectively, served as BBB breakdown model in vivo and in vitro. Evans-Blue (EB) extravagation and ¹²⁵I-albumin were used to quantify BBB dysfunction; UPLC–MS/MS analytical method was performed to determine accurately the concentration of verapamil in brain tissue and cell. Flow cytometry, immunohistochemistry and western blotting were applied to evaluate transport function and protein expression of P-gp.

Results

Overexpressed ICAM-1 and MMP-9 mediated BBB dysfunction after ischemia, which induced EB leakage and ¹²⁵I-albumin uptake increase. Enhanced accumulation of verapamil in brain tissue, but intracellular concentration reduced evidently after H/R injury. Transcellular transportation of verapamil elevated when P-gp function or expression was inhibited after H/R injury.

Conclusion

These data indicated that BBB penetration of verapamil under ischemia condition was not only depending on BBB breakdown, but also regulated by P-gp.     

Phylogenomic and syntenic data demonstrate complex evolutionary processes in early radiation of the rosids

Some of the most vexing problems of deep level relationship that remain in angiosperms involve the superrosids. The superrosid clade contains a quarter of all angiosperm species, with 18 orders in three subclades (Vitales, Saxifragales and core rosids) exhibiting remarkable morphological and ecological diversity. To help resolve deep-level relationships, we constructed a high-quality chromosome-level genome assembly for Tiarella polyphylla (Saxifragaceae) thus providing broader genomic representation of Saxifragales. Whole genome microsynteny analysis of superrosids showed that Saxifragales shared more synteny clusters with core rosids than Vitales, further supporting Saxifragales as more closely related with core rosids. To resolve the ordinal phylogeny of superrosids, we screened 122 single copy nuclear genes from genomes of 36 species, representing all 18 superrosid orders. Vitales were recovered as sister to all other superrosids (Saxifragales + core rosids). Our data suggest dramatic differences in relationships compared to earlier studies within core rosids. Fabids should be restricted to the nitrogen-fixing clade, while Picramniales, the Celastrales-Malpighiales (CM) clade, Huerteales, Oxalidales, Sapindales, Malvales and Brassicales formed an “expanded” malvid clade. The Celastrales-Oxalidales-Malpighiales (COM) clade (sensu APG IV) was not monophyletic. Crossosomatales, Geraniales, Myrtales and Zygophyllales did not belong to either of our well-supported malvids or fabids. There is strong discordance between nuclear and plastid phylogenetic hypotheses for superrosid relationships; we show that this is best explained by a combination of incomplete lineage sorting and ancient reticulation.     

以人精子抗原消化道免疫后的体液免疫反应

The inbred Balb/c and C57 mice, and the outbred Swiss Webster mice were intragastrointestinally immunized with human sperm antigens. The lymphocytes from the spleen, mesenteric lymph node (MLN), Peyer's patch (PP) and uterus or epididymis were isolated and cultured. The lymphocyte-secreting antisperm IgG and IgA and the antisperm antibodies in the gut wash and serum were determined with enzyme-linked immunosorbent assay (ELISA). In the Balb/c and Swiss Webster mice, the immune responses to sperm have shown to be stronger than that in C57, stronger in female than in male. The antigenicity of sperm membrane extracts seems to be higher than that of whole sperm. Antisperm antibodies secreted by lymphocytes from the epididymis and uterus have demonstrated to be detectable. For stimulation of the local immune response, the intra-PP and intralumina immunizations are more effective than others.     

多重耐药大肠杆菌耐药基因与整合子遗传标记基因间的相关性

[目的]对多重耐药大肠埃希菌(Escherichia coli)临床株的β-内酰胺酶类(β-lactamases,BLs)和氨基糖苷钝化酶类(aminoglycoside modifying enzymes,AMEs)耐药基因与Ⅰ-Ⅲ类整合子遗传标记基因之间的相关性进行研究.[方法]采用VITEK-GNS药敏卡测定13...     

Synchronization,Slippage, and Unbundling of Driven Helical Flagella

Peritrichous bacteria exploit bundles of helical flagella for propulsion and chemotaxis. Here, changes in the swimming direction (tumbling) are induced by a change of the rotational frequency of some flagella. Employing coarse-grained modeling and simulations, we investigate the dynamical properties of helical flagella bundles driven by mismatched motor torques. Over a broad range of distances between the flagella anchors and applied torque differences, we find a stable bundled state, which is important for a robust directional motion of a bacterium. With increasing torque difference, a phase lag in the flagellar rotations develops, followed by slippage and ultimately unbundling, which sensitively depends on the anchoring distance of neighboring flagella. In the slippage and drift states, the different rotation frequencies of the flagella generate a tilting torque on the bacterial body, which implies a change of the swimming direction as observed experimentally.     

骨组织细胞Cx43形成的间隙连接及半通道研究进展

连接子蛋43（connexin 43,Cx43）是骨组织中主要的间隙连接（gap junction）蛋白和半通道（hemichannel）蛋白,由Cx43形成的间隙连接及半通道实现了骨组织细胞间的直接通讯。连接子蛋白对骨组织的正常发育、骨重建过程的建立与平衡是非常重要的。目前研究指出,Cx43不仅参与了骨组织的力学响应过程,也参与了二磷酸盐、甲状旁腺激素等药物对骨重建的调节过程。该文以骨组织细胞内信号传递途径的关键分子Cx43为对象,就其目前的研究现状作一综述。     

动物的试-错学习行为

试-错学习是动物学习行为的一种类型。介绍了试-错学习的基本概念,并重点介绍了一些动物类群的试-错学习试验,其中包括涡虫、蚯蚓、蚂蚁、蜜蜂、鱼类和鸟类。