Whole-genome sequence of Corynebacterium pseudotuberculosis PAT10 strain isolated from sheep in Patagonia, Argentina

In this work, we report the complete genome sequence of a Corynebacterium pseudotuberculosis PAT10 isolate, collected from a lung abscess in an Argentine sheep in Patagonia, whose pathogen also required an investigation of its pathogenesis. Thus, the analysis of the genome sequence offers a means to better understanding of the molecular and genetic basis of virulence of this bacterium.     

Role of Rbp1 in the acquired chill-light tolerance of cyanobacteria

Synechocystis sp. strain PCC 6803 cultured at 30°C losses viability quickly under chill (5°C)-light stress but becomes highly tolerant to the stress after conditioning at 15°C (Y. Yang, C. Yin, W. Li, and X. Xu, J. Bacteriol. 190:1554-1560, 2008). Hypothetically, certain factors induced during preconditioning are involved in acquisition of chill-light tolerance. In this study, Rbp1 (RNA-binding protein 1) rather than Rbp2 was found to be accumulated during preconditioning, and the accumulation of Rbp1 was correlated with the increase of chill-light tolerance. Inactivation of its encoding gene rbp1 led to a great reduction in the acquired chill-light tolerance, while ectopic expression of rbp1 enabled the cyanobacterium to survive the chill-light stress without preconditioning. Microarray analyses suggested that the Rbp1-dependent chill-light tolerance may not be based on its influence on mRNA abundance of certain genes. Similarly to that in Synechocystis, the Rbp1 homologue(s) can be accumulated in Microcystis cells collected from a subtropic lake in low-temperature seasons. Rbp1 is the first factor shown to be both accumulated early during preconditioning and directly involved in development of chill-light tolerance in Synechocystis. Its accumulation may greatly enhance the overwintering capability in certain groups of cyanobacteria.     

EGFR, Wingless and JAK/STAT signaling cooperatively maintain Drosophila intestinal stem cells

Tissue-specific adult stem cells are commonly associated with local niche for their maintenance and function. In the adult Drosophila midgut, the surrounding visceral muscle maintains intestinal stem cells (ISCs) by stimulating Wingless (Wg) and JAK/STAT pathway activities, whereas cytokine production in mature enterocytes also induces ISC division and epithelial regeneration, especially in response to stress. Here we show that EGFR/Ras/ERK signaling is another important participant in promoting ISC maintenance and division in healthy intestine. The EGFR ligand Vein is specifically expressed in muscle cells and is important for ISC maintenance and proliferation. Two additional EGFR ligands, Spitz and Keren, function redundantly as possible autocrine signals to promote ISC maintenance and proliferation. Notably, over-activated EGFR signaling could partially replace Wg or JAK/STAT signaling for ISC maintenance and division, and vice versa. Moreover, although disrupting any single one of the three signaling pathways shows mild and progressive ISC loss over time, simultaneous disruption of them all leads to rapid and complete ISC elimination. Taken together, our data suggest that Drosophila midgut ISCs are maintained cooperatively by multiple signaling pathway activities and reinforce the notion that visceral muscle is a critical component of the ISC niche.     

Myocardial ischemia activates an injurious innate immune signaling via cardiac heat shock protein 60 and Toll-like receptor 4

Innate immune response after transient ischemia is the most common cause of myocardial inflammation and may contribute to injury, yet the detailed signaling mechanisms leading to such a response are not well understood. Herein we tested the hypothesis that myocardial ischemia activates interleukin receptor-associated kinase-1 (IRAK-1), a kinase critical for the innate immune signaling such as that of Toll-like receptors (TLRs), via a mechanism that involves heat shock proteins (HSPs) and TLRs. Coronary artery occlusion induced a rapid myocardial IRAK-1 activation within 30 min in wild-type (WT), TLR2(-/-), or Trif(-/-) mice, but not in TLR4(def) or MyD88(-/-) mice. HSP60 protein was markedly increased in serum or in perfusate of isolated heart following ischemia/reperfusion (I/R). In vitro, recombinant HSP60 induced IRAK-1 activation in cells derived from WT, TLR2(-/-), or Trif(-/-) mice, but not from TLR4(def) or MyD88(-/-) mice. Both myocardial ischemia- and HSP60-induced IRAK-1 activation was abolished by anti-HSP60 antibody. Moreover, HSP60 treatment of cardiomyocytes (CMs) led to marked activation of caspase-8 and -3, but not -9. Expression of dominant-negative mutant of Fas-associated death domain protein or a caspase-8 inhibitor completely blocked HSP60-induced caspase-8 activation, suggesting that HSP60 likely activates an apoptotic program via the death-receptor pathway. In vivo, I/R-induced myocardial apoptosis and cytokine expression were significantly attenuated in TLR4(def) mice or in WT mice treated with anti-HSP60 antibody compared with WT controls. Taken together, the current study demonstrates that myocardial ischemia activates an innate immune signaling via HSP60 and TLR4, which plays an important role in mediating apoptosis and inflammation during I/R.     

The expression of Fas/FasL and apoptosis in yak placentomes

To clarify the status and distribution of Fas and Fas-Ligand (FasL) in yak's placentomes, immunohistochemistry (IHC) was carried out to analyze the expression and location of Fas and FasL in paraffin embedded sections. The area of positive stained sites was selected and measured using image analyses software (Image Pro-Plus 6.0). So the positive index (PI) was calculated to estimate the intensity of protein expression according to the percentage of positive area in corresponding compartment of the placentomes. In cotyledonary villi, Fas mainly presented on the villous trophoblast cells in early pregnancy. The positive index reached a maximum of 20.7±8.8 at the third month of pregnancy. Then Fas was declined rapidly along with the progress of gestation and the value was 2.8±1.3 after the 7th month of pregnancy. However, in caruncular crypts, Fas was mainly localized to isolated cells or clustered cells of the uterine stroma underlying the caruncular epithelium. The intensity was lower and the positive index was changed between 4.7±0.9 and 8.5±1.6 throughout gestation. For FasL, it gave a distinct immunostained distribution. In cotyledonary villi, FasL was localized dominantly and strongly in the cytoplasm of binuclear, mononuclear and trinuclear trophoblast giant cells (TGC). The positive index of FasL maintained a moderate level all through the gestation. In caruncular crypts, the expression of FasL was weak and the positive index was declined. Only in the first two months, maternal uterine epithelial cells intensely expressed FasL and the index reached to the maximum of 19.8±5.2. The result of subcellular localization of Fas ligand using immunoelectron microscopy technology indicated that FasL was subcellular located in some intracellular vesicles of TGC. This means the vesicles of trophoblast giant cells itself can express FasL. By the TUNEL method, apoptosis was detected in yak placentomes. The amount of apoptotic cells was rare. The fetal chorionic trophoblast cells and caruncular crypt epithelium cells demonstrated higher percentage of apoptosis in middle pregnancy, which suggested that apoptosis plays an important role in placental cellular regeneration. In addition, the apoptosis of maternal caruncular stromal cells provides a local mechanism for maternal immunotolerance to the fetus and this mechanism was mediated by Fas-FasL pathway.     

Current evidences on vascular endothelial growth factor polymorphisms and breast cancer susceptibility

Several polymorphisms of vascular endothelial growth factor (VEGF) such as 936 C/T, −2578 C/A, −406 C/T, and −1154 G/A polymorphism have been identified. Published data on the association between VEGF polymorphisms and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Crude OR with 95% CI was used to assess the strength of association between them. For VEGF 936C/T polymorphism, a total of 10 studies including 7,685 cases and 7,915 controls were involved in this meta-analysis. Overall, no significant associations were found between VEGF 936C/T polymorphism and breast cancer risk when all studies pooled into the meta-analysis (TC vs. CC: OR = 0.904, 95% CI = 0.797–1.024; TT vs. CC: OR = 0.974, 95% CI = 0.786–1.205; dominant model: OR = 0.911, 95% CI = 0.811–1.024; and recessive model: OR = 0.991, 95% CI = 0.801–1.226). In the subgroup analysis by ethnicity, still no significant associations were found for all comparison models. For −2578 C/A, −406 C/T, and −1154 G/A polymorphism, there were too limited data to perform a meta-analysis. In conclusion, this meta-analysis suggests that the VEGF 936C/T polymorphism may be not associated with breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well matched controls are warranted to confirm this finding.     

聚合高分子电解质分离纯化蛋白质

聚合高分子电解质含有大量阳离子或阴离子,通过静电作用结合带相反电荷的蛋白质,生成聚合高分子电解质-蛋白质复合物,电解质-蛋白质复合物通过桥连作用或疏水作用形成沉淀颗粒;聚合高分子电解质的选择性沉淀作用受电解质的分子量、添加剂量、溶液离子强度和pH的影响。用高分子电解质从大规模的低浓度溶液中选择性地沉淀目的蛋白质,为生物工程的下游处理开辟了一条新途径。     

南海链霉菌SCSIO 1635中抗霉素类化合物的分离鉴定(英文)

我们从南海海底沉积环境分离了一株放线菌SCSIO1635,经16S rDNA的序列分析将该株菌鉴定为链霉菌属。我们从该菌的发酵液中分离得到了4个化合物,经质谱和核磁共振波谱解析,确定为抗霉素类化合物:异构体antimycin A1a和A1b(1)、deisovalerylblastmycin(2)、kitamycin A(3)和antimycin A9(4)。     

Tailor-made type II <Emphasis Type="Italic">Pseudomonas</Emphasis> PHA synthases and their use for the biosynthesis of polylactic acid and its copolymer in recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis>

Previously, we have developed metabolically engineered Escherichia coli strains capable of producing polylactic acid (PLA) and poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] by employing evolved Clostridium propionicum propionate CoA transferase (Pct _Cp ) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1 _Ps6-19). Introduction of mutations four sites (E130, S325, S477, and Q481) of PhaC1 _Ps6-19 have been found to affect the polymer content, lactate mole fraction, and molecular weight of P(3HB-co-LA). In this study, we have further engineered type II Pseudomonas PHA synthases 1 (PhaC1s) from Pseudomonas chlororaphis, Pseudomonas sp. 61-3, Pseudomonas putida KT2440, Pseudomonas resinovorans, and Pseudomonas aeruginosa PAO1 to accept short-chain-length hydroxyacyl-CoAs including lactyl-CoA and 3-hydroxybutyryl-CoA as substrates by site-directed mutagenesis of four sites (E130, S325, S477, and Q481). All PhaC1s having mutations in these four sites were able to accept lactyl-CoA as a substrate and supported the synthesis of P(3HB-co-LA) in recombinant E. coli, whereas the wild-type PhaC1s could not accumulate polymers in detectable levels. The contents, lactate mole fractions, and the molecular weights of P(3HB-co-LA) synthesized by recombinant E. coli varied depending upon the source of the PHA synthase and the mutants used. PLA homopolymer could also be produced at ca. 7 wt.% by employing the several PhaC1 variants containing E130D/S325T/S477G/Q481K quadruple mutations in wild-type E. coli XL1-Blue.