The N-terminal domain of PsaF: Precise recognition site for binding and fast electron transfer from cytochrome c6 and plastocyanin to photosystem I of Chlamydomonas reinhardtii

The PsaF-deficient mutant 3bF of Chlamydomonas reinhardtii was used to modify PsaF by nuclear transformation and site-directed mutagenesis. Four lysine residues in the N-terminal domain of PsaF, which have been postulated to form the positively charged face of a putative amphipathic α-helical structure were altered to K12P, K16Q, K23Q, and K30Q. The interactions between plastocyanin (pc) or cytochrome c6 (cyt c6) and photosystem I (PSI) isolated from wild type and the different mutants were analyzed using crosslinking techniques and flash absorption spectroscopy. The K23Q change drastically affected crosslinking of pc to PSI and electron transfer from pc and cyt c6 to PSI. The corresponding second order rate constants for binding of pc and cyt c6 were reduced by a factor of 13 and 7, respectively. Smaller effects were observed for mutations K16Q and K30Q, whereas in K12P the binding was not changed relative to wild type. None of the mutations affected the half-life of the microsecond electron transfer performed within the intermolecular complex between the donors and PSI. The fact that these single amino acid changes within the N-terminal domain of PsaF have different effects on the electron transfer rate constants and dissociation constants for both electron donors suggests the existence of a rather precise recognition site for pc and cyt c6 that leads to the stabilization of the final electron transfer complex through electrostatic interactions.

Cyclic AMP regulates potassium channel expression in C6 glioma by destabilizing Kv1.1 mRNA

The tissue distributions and physiological properties of a variety of cloned voltage-gated potassium channel genes have been characterized extensively, yet relatively little is known about the mechanisms controlling expression of these genes. Here, we report studies on the regulation of Kv1.1 expressed endogenously in the C6 glioma cell line. We demonstrate that elevation of intracellular cAMP leads to the accelerated degradation of Kv1.1 RNA. The cAMP-induced decrease in Kv1.1 RNA is followed by a decrease in Kv1.1 protein and a decrease in the whole cell sustained K+ current amplitude. Dendrotoxin-I, a relatively specific blocker of Kv1.1, blocks 96% of the sustained K+ current in glioma cells, causing a shift in the resting membrane potential from −40 mV to −7 mV. These data suggest that expression of Kv1.1 contributes to setting the resting membrane potential in undifferentiated glioma cells. We therefore suggest that receptor-mediated elevation of cAMP reduces outward K+ current density by acting at the translational level to destabilize Kv1.1 RNA, an additional mechanism for regulating potassium channel gene expression.

Identification of differentially expressed genes in a Giardia lamblia WB C6 clone resistant to nitazoxanide and metronidazole.

OBJECTIVES The characterization of differential gene expression in Giardia lamblia WB C6 strain C4 resistant to metronidazole and nitazoxanide using microarray technology and quantitative real-time PCR. METHODS In a previous study, we created and characterized the G. lamblia WB C6 clone C4 resistant to nitazoxanide and metronidazole. In this study, using a microarray-based approach, we have identified open-reading frames (ORFs) that were differentially expressed in C4 when compared with its wild-type WB C6. Using quantitative real-time PCR, we have validated the expression patterns of some of those ORFs, focusing on chaperones such as heat-shock proteins in wild-type and C4 trophozoites. In order to induce an antigenic shift, trophozoites of both strains were subjected to a cycle of en- and excystation. Expression of selected genes and resistance to nitazoxanide and metronidazole were investigated after this cycle. RESULTS Forty of a total of 9115 ORFs were found to be up-regulated and 46 to be down-regulated in C4 when compared with wild-type. After a cycle of en- and excystation, resistance of C4 to nitazoxanide and metronidazole was lost. Resistance formation and en-/excystation were correlated with changes in expression of ORFs encoding for major surface antigens such as the variant surface protein TSA417 or AS7 ('antigenic shift'). Moreover, expression patterns of the cytosolic heat-shock protein HSP70 B2, HSP40, and of the previously identified nitazoxanide-binding proteins nitroreductase and protein disulphide isomerase PDI4 were correlated with resistance and loss of resistance after en-/excystation. C4 trophozoites had a higher thermotolerance level than wild-type trophozoites. After en-/excystation, this tolerance was lost. CONCLUSIONS These results suggest that resistance formation in Giardia to nitazoxanide and metronidazole is correlated with altered expression of genes involved in stress response such as heat-shock proteins.

Biological Atlas of the Arctic Seas 2000: Physical oceanography, hydrochemistry, meteorology, and plankton of the Barents and Kara Seas

Presented are physical and biological data for the region extending from the Barents Sea to the Kara Sea during 158 scientific cruises for the period 1913-1999. Maps with the temporal distribution of physical and biological variables of the Barents and Kara Seas are presented, with proposed quality control criteria for phytoplankton and zooplankton data. Changes in the plankton community structure between the 1930s, 1950s, and 1990s are discussed. Multiple tables of Arctic Seas phytoplankton and zooplankton species are presented, containing ecological and geographic characteristics for each species, and images of live cells for the dominant phytoplankton species.

Heterogeneously catalyzed hydrothermal processing of C5-C6 sugars

Biomass has been long exploited as an anthropogenic energy source; however, the 21st century challenges of energy security and climate change are driving resurgence in its utilization both as a renewable alternative to fossil fuels and as a sustainable carbon feedstock for chemicals production. Deconstruction of cellulose and hemicellulose carbohydrate polymers into their constituent C5 and C6 sugars, and subsequent heterogeneously catalyzed transformations, offer the promise of unlocking diverse oxygenates such as furfural, 5-hydroxymethylfurfural, xylitol, sorbitol, mannitol, and gluconic acid as biorefinery platform chemicals. Here, we review recent advances in the design and development of catalysts and processes for C5-C6 sugar reforming into chemical intermediates and products, and highlight the challenges of aqueous phase operation and catalyst evaluation, in addition to process considerations such as solvent and reactor selection.

Uptake and toxicity of copper oxide nanoparticles in C6 glioma cells

Copper oxide nanoparticles (CuO-NPs) are frequently used for many technical applications, but are also known for their cell toxic potential. In order to investigate a potential use of CuO-NPs as a therapeutic drug for glioma treatment, we have investigated the consequences of an application of CuO-NPs on the cellular copper content and cell viability of C6 glioma cells. CuO-NPs were synthesized by a wet-chemical method and were coated with dimercaptosuccinic acid and bovine serum albumin to improve colloidal stability in physiological media. Application of these protein-coated nanoparticles (pCuO-NPs) to C6 cells caused a strong time-, concentration- and temperature-dependent copper accumulation and severe cell death. The observed loss in cellular MTT-reduction capacity, the loss in cellular LDH activity and the increase in the number of propidium iodide-positive cells correlated well with the specific cellular copper content. C6 glioma cells were less vulnerable to pCuO-NPs compared to primary astrocytes and toxicity of pCuO-NPs to C6 cells was only observed for incubation conditions that increased specific cellular copper contents above 20 nmol copper per mg protein. Both cellular copper accumulation as well as the pCuO-NP-induced toxicity in C6 cells were prevented by application of copper chelators, but not by endocytosis inhibitors, suggesting that liberation of copper ions from the pCuO-NPs is the first step leading to the observed toxicity of pCuO-NP-treated glioma cells.

Defective interfering viral particles in acute dengue infections

While much of the genetic variation in RNA viruses arises because of the error-prone nature of their RNA-dependent RNA polymerases, much larger changes may occur as a result of recombination. An extreme example of genetic change is found in defective interfering (DI) viral particles, where large sections of the genome of a parental virus have been deleted and the residual sub-genome fragment is replicated by complementation by co-infecting functional viruses. While most reports of DI particles have referred to studies in vitro, there is some evidence for the presence of DI particles in chronic viral infections in vivo. In this study, short fragments of dengue virus (DENV) RNA containing only key regulatory elements at the 3' and 5' ends of the genome were recovered from the sera of patients infected with any of the four DENV serotypes. Identical RNA fragments were detected in the supernatant from cultures of Aedes mosquito cells that were infected by the addition of sera from dengue patients, suggesting that the sub-genomic RNA might be transmitted between human and mosquito hosts in defective interfering (DI) viral particles. In vitro transcribed sub-genomic RNA corresponding to that detected in vivo could be packaged in virus like particles in the presence of wild type virus and transmitted for at least three passages in cell culture. DENV preparations enriched for these putative DI particles reduced the yield of wild type dengue virus following co-infections of C6-36 cells. This is the first report of DI particles in an acute arboviral infection in nature. The internal genomic deletions described here are the most extensive defects observed in DENV and may be part of a much broader disease attenuating process that is mediated by defective viruses.

A new approach for trip generation estimation for use in traffic impact assessments

Findings from an online survey conducted by Queensland University of Technology (QUT) shows that Australia is suffering from a lack of data reflecting trip generation for use in Traffic Impact Assessments (TIAs). Current independent variables for trip generation estimation are not able to create robust outcomes as well. It is also challenging to account for the impact of the new development on public and active transport as well as the effect of trip chaining behaviour in Australian TIA studies. With this background in mind, research is being implemented by QUT to find a new approach developing a combined model of trip generation and mode choice with consideration of trip chaining effects. It is expected that the model will provide transferable outcomes as it is developed based on socio-demographic parameters. Child Care Centres within the Brisbane area have been nominated for model development. At the time, the project is in the data collection phase. Findings from the pilot survey associated with capturing trip chaining and mode choice information reveal that applying questionnaire is able to capture required information in an acceptable level. The result also reveals that several centres within an area should be surveyed in order to provide sufficient data for trip chaining and modal split analysis.

Bus and car travel time on urban networks : integrating Bluetooth and bus vehicle identification data

Travel time in an important transport performance indicator. Different modes of transport (buses and cars) have different mechanical and operational characteristics, resulting in significantly different travel behaviours and complexities in multimodal travel time estimation on urban networks. This paper explores the relationship between bus and car travel time on urban networks by utilising the empirical Bluetooth and Bus Vehicle Identification data from Brisbane. The technologies and issues behind the two datasets are studied. After cleaning the data to remove outliers, the relationship between not-in-service bus and car travel time and the relationship between in-service bus and car travel time are discussed. The travel time estimation models reveal that the not-in-service bus travel time are similar to the car travel time and the in-service bus travel time could be used to estimate car travel time during off-peak hours

Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis

Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distributions of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. Twenty-four healthy trained males were assigned to three groups (n = 8/group) and undertook a bout of resistance exercise followed by ingestion of 80 g of whey protein throughout 12 h recovery in one of the following protocols: 8 × 10 g every 1.5 h (PULSE); 4 × 20 g every 3 h (intermediate: INT); or 2 × 40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h post exercise. Resting and post-exercise MPS (l-[ring-(13)C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols increased MPS above rest throughout 1-12 h recovery (88-148%, P < 0.02), but INT elicited greater MPS than PULSE and BOLUS (31-48%, P < 0.02). In general signalling showed a BOLUS>INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has the potential to maximize outcomes of resistance training for attaining peak muscle mass.

Boken, berättelsen, pengarna I den digitala tidsåldern [The book, the story and the money in the digital age]

År 2012 är distribution av litteratur via internet inte längre en framtidsvision, utan ett etablerat format vid sidan av traditionella format som exempelvis pocketboken, den inbundna boken och ljudboken (AAP 2011; Amazon 2011; PaidContent 2011). Men den digitala tekniken etablerar inte enbart ett nytt format, utan förändrar också grundförutsättningarna för litterära konstformer och marknader. Detta kapitel behandlar en betydelsefull aspekt av denna förändring, nämligen hur den digitala tekniken påverkar relationen mellan läsare och författare och ökar läsarens inflytande över den kreativa processen. I den digitala tidsåldern är det möjligt att skapa berättelser online i en interaktiv process som involverar både läsare och författare. Kapitlet presenterar modeller för hur sådan “samproducerad e-litteratur” förändrar marknaden för litteratur och hur den påverkar den traditionella litteraturen.

The mechanical rigidity of the extracellular matrix regulates the structure, motility, and proliferation of glioma cells

Glioblastoma multiforme (GBM) is a malignant astrocytoma of the central nervous system associated with a median survival time of 15 months, even with aggressive therapy. This rapid progression is due in part to diffuse infiltration of single tumor cells into the brain parenchyma, which is thought to involve aberrant interactions between tumor cells and the extracellular matrix (ECM). Here, we test the hypothesis that mechanical cues from the ECM contribute to key tumor cell properties relevant to invasion. We cultured a series of glioma cell lines (U373-MG, U87-MG, U251-MG, SNB19, C6) on fibronectin-coated polymeric ECM substrates of defined mechanical rigidity and investigated the role of ECM rigidity in regulating tumor cell structure, migration, and proliferation. On highly rigid ECMs, tumor cells spread extensively, form prominent stress fibers and mature focal adhesions, and migrate rapidly. As ECM rigidity is lowered to values comparable with normal brain tissue, tumor cells appear rounded and fail to productively migrate. Remarkably, cell proliferation is also strongly regulated by ECM rigidity, with cells dividing much more rapidly on rigid than on compliant ECMs. Pharmacologic inhibition of nonmuscle myosin II–based contractility blunts this rigidity-sensitivity and rescues cell motility on highly compliant substrates. Collectively, our results provide support for a novel model in which ECM rigidity provides a transformative, microenvironmental cue that acts through actomyosin contractility to regulate the invasive properties of GBM tumor cells.

Study of electron states of solids by techniques of electron spectroscopy

Studies of valence bands and core levels of solids by photoelectron spectroscopy are described at length. Satellite phenomena in the core level spectra have been discussed in some detail and it has been pointed out that the intensity of satellites appearing next to metal and ligand core levels critically depends on the metal-ligand overlap. Use of photoelectron spectroscopy in investigating metal-insulator transitions and spin-state transitions in solids is examined. It is shown that relative intensities of metal Auger lines in transition metal oxides and other systems provide valuable information on the valence bands. Occurrence of interatomic Auger transitions in competition with intraatomic transitions is discussed. Applications of electron energy loss spectroscopy and other techniques of electron spectroscopy in the study of gas-solid interactions are briefly presented.