Redox potential control in anaerobic Clostridium beijerinckii fermentation using single-use vessels

Redox potential is an important physiochemical factor which measures the tendency of the medium to acquire electrons. In Clostridium beijerinckii fermentation, redox potential indicates the status of the NAD(P)+ pool regeneration which directs the electron flow leading to solvent production including butanol. In this study, anaerobic C. beijerinckii fermentation was conducted in Eppendorf BioBLU® 3f Single-Use Vessels controlled by the BioFlo® 120 bioprocess control station. The parameters being monitored throughout the fermentation were redox potential and pH using ISM® redox/pH sensors. The objectives of this study were (1) to investigate the effects of redox control on the growth and butanol production of C. beijerinckii; and (2) to validate the suitability of the BioFlo 120 and BioBLU 3f Single-Use Vessel for anaerobic fermentation applications. When C. beijerinckii was grown without redox control, a continuous change of redox potential was observed in the broth. When fermentation ended at 124 h, the optical density at 600 nm (OD600) was 0.8, glucose consumption was 33 % and butanol production was limited. When the redox potential was controlled at -500 mV by redox sensor guided addition of Na2S·9H2O solution, the OD600 was 1.6, glucose consumption was 51 %, and butanol production showed a 2-fold increase. In summary, with the combination of ISM redox sensor and BioBLU Single-Use Vessel, the high variability of redox potential during C. beijerinckii fermentation can be actively controlled to drastically increase biomass growth and solvent production

The juxtamembrane and carboxy-terminal domains of Arabidopsis PRK2 are critical for ROP-induced growth in pollen tubes.

Polarized growth of pollen tubes is a critical step for successful reproduction in angiosperms and is controlled by ROP GTPases. Spatiotemporal activation of ROP (Rho GTPases of plants) necessitates a complex and sophisticated regulatory system, in which guanine nucleotide exchange factors (RopGEFs) are key components. It was previously shown that a leucine-rich repeat receptor-like kinase, Arabidopsis pollen receptor kinase 2 (AtPRK2), interacted with RopGEF12 for its membrane recruitment. However, the mechanisms underlying AtPRK2-mediated ROP activation in vivo are yet to be defined. It is reported here that over-expression of AtPRK2 induced tube bulging that was accompanied by the ectopic localization of ROP-GTP and the ectopic distribution of actin microfilaments. Tube depolarization was also induced by a potentially kinase-dead mutant, AtPRK2K366R, suggesting that the over-expression effect of AtPRK2 did not require its kinase activity. By contrast, deletions of non-catalytic domains in AtPRK2, i.e. the juxtamembrane (JM) and carboxy-terminal (CT) domains, abolished its ability to affect tube polarization. Notably, AtPRK2K366R retained the ability to interact with RopGEF12, whereas AtPRK2 truncations of these non-catalytic domains did not. Lastly, it has been shown that the JM and CT domains of AtPRK2 were not only critical for its interaction with RopGEF12 but also critical for its distribution at the plasma membrane. These results thus provide further insight into pollen receptor kinase-mediated ROP activation during pollen tube growth

Warburg Effects in Cancer and Normal Proliferating Cells: Two Tales of the Same Name

It has been observed that both cancer tissue cells and normal proliferating cells (NPCs) have the Warburg effect. Our goal here is to demonstrate that they do this for different reasons. To accomplish this, we have analyzed the transcriptomic data of over 7000 cancer and control tissues of 14 cancer types in TCGA and data of five NPC types in GEO. Our analyses reveal that NPCs accumulate large quantities of ATPs produced by the respiration process before starting the Warburg effect, to raise the intracellular pH from ∼6.8 to ∼7.2 and to prepare for cell division energetically. Once cell cycle starts, the cells start to rely on glycolysis for ATP generation followed by ATP hydrolysis and lactic acid release, to maintain the elevated intracellular pH as needed by cell division since together the three processes are pH neutral. The cells go back to the normal respiration-based ATP production once the cell division phase ends. In comparison, cancer cells have reached their intracellular pH at ∼7.4 from top down as multiple acid-loading transporters are up-regulated and most acid-extruding ones except for lactic acid exporters are repressed. Cancer cells use continuous glycolysis for ATP production as way to acidify the intracellular space since the lactic acid secretion is decoupled from glycolysis-based ATP generation and is pH balanced by increased expressions of acid-loading transporters. Co-expression analyses suggest that lactic acid secretion is regulated by external, non-pH related signals. Overall, our data strongly suggest that the two cell types have the Warburg effect for very different reasons

Distributed OSN Crawling System based on Ajax Simulation

AbstractIn the age of Web2.0, lots of online social networks (OSNs) like Facebook, Twitter, WeiBo become the most popular information transform platform, which catch more and more attention from Information Retrieval (IR). However, traditional web crawling System get into trouble because of the complicated OSN web pages, the rapid message exploding and the heavy using of Asynchronous JavaScript and XML(AJAX). We design and implement a distributed system based on Message Oriented Middleware (MOM) and Ajax simulation, which crawls 70 millions of Twitter detail items in one month. The data Acquisition shows that the crawling with Ajax simulation is able to get items loaded by Ajax without limitations, the distributed system based on MOM and Ajax simulation is able to crawl massive OSN data completely, quickly, frequently and unrestrictedly

Principal Component Regression Analysis of Nutrition Factors and Physical Activities with Diabetes

The associations of nutrition factors and physical activities with adult diabetes are inconsistent; while most of these factors are inter correlated. The aims of this study are to overcome the disturbance of the multicollinearity of the risk factors and examine the associations of these factors with diabetes using the principal component analysis (PCA) and regression analysis with principal component scores (PCS). Totally, 659 adults with diabetes and 2827 non-diabetic were selected from the 2012 Health Information National Trends Survey (HINTS 4, Cycle 2). PCA was utilized to deal with multicollinearity of the risk factors. Weighted univariate and multiple logistic regression analyses were used to estimate the associations of potential factors and PCS with diabetes. The odds ratios (ORs) with 95% confidence intervals (CIs) were estimated. The first 3 PCs for nutrition factors and physical activities could explain 70% variances. The first principal component (PC1) is a measure of nutrition factors (fruit and vegetables consumption), PC2 is a measure for physical activities (moderate exercise and strength training), and PC3 is about calorie information use and soda use. Weighted multiple logistic regression showed that African Americans, middle aged adults (45-64 years), elderly (65+), never married, and with lower education were associated with increased odds of diabetes. After adjusting for others factors, the PC1 showed marginal association with diabetes (OR=0.84, 95% CI=0.70-1.01); while PC2 and PC3 revealed significant associations with diabetes (OR=0.73, 95% CI=0.61-0.86 and OR=0.85, 95% CI=0.74-0.99, respectively). In conclusion, PCA can be used to reduce the indicators in complex survey data. The first 3 PCs of nutrition factors and physical activities were associated with diabetes. Promotion of health food and physical activities should be encouraged to help decrease the prevalence of diabetes