A microbial fuel cell operating at low pH using the acidophile Acidiphilium cryptum

For the first time, a microbial fuel cell has been developed using an acidophile, Acidiphilium cryptum, as the anode biocatalyst. Electricity production using its natural electron acceptor, iron, as the electron mediating agent at pH values < or =4.0 was demonstrated. Accumulation of Fe(III) at the electrode, however, restricted current output. The combination of nitrilotriacetic acid and Phenosafranin as electron mediators increased the power output to 12.7 mW/m(2) in a two-chamber air-sparged fuel cell. Direct electron transfer from the microorganisms to the anode was also investigated but was not detected under the conditions studied.     

Small molecule modulators of eukaryotic initiation factor 2α kinases,the key regulators of protein synthesis

Eukaryotic initiation factor 2 alpha kinases (eIF-2α kinases) are key mediators of stress response in cells. In mammalian cells, there are four eIF-2α kinases, namely HRI (Heme-Regulated Inhibitor), PKR (RNA-dependent Protein Kinase), PERK (PKR-like ER Kinase) and GCN2 (General Control Non-derepressible 2). These kinases get activated during diverse cytoplasmic stress conditions and phosphorylate the alpha-subunit of eIF2, leading to global protein synthesis inhibition. Therefore, eIF-2α kinases play a vital role in various cellular processes such as proliferation, differentiation, apoptosis and cell signaling. Deregulation of eIF-2α kinases and protein synthesis has been linked to numerous pathological conditions such as certain cancers, anemia and neurodegenerative disorders. Thus, modulation of these kinases by small molecules holds a great therapeutic promise. In this review we have compiled the available information on inhibitors and activators of these four eIF-2α kinases. The review concludes with a note on the selectivity issue of currently available modulators and future perspectives for the design of specific small molecule probes.     

Myelination and node of Ranvier formation on sensory neurons in a defined in vitro system

One of the most important developmental modifications of the nervous system is Schwann cell myelination of axons. Schwann cells ensheath axons to create myelin segments to provide protection to the axon as well as increase the conduction of action potentials. In vitro neuronal systems provide a unique modality to study a variety of factors influencing myelination as well as diseases associated with myelin sheath degradation. This work details the development of a patterned in vitro myelinating dorsal root ganglion culture. This defined system utilized a serum-free medium in combination with a patterned substrate, utilizing the cytophobic and cytophilic molecules (poly)ethylene glycol (PEG) and N-1[3 (trimethoxysilyl) propyl] diethylenetriamine (DETA), respectively. Directional outgrowth of the neurites and subsequent myelination was controlled by surface modifications, and conformity to the pattern was measured over the duration of the experiments. The myelinated segments and nodal proteins were visualized and quantified using confocal microscopy. This tissue-engineered system provides a highly controlled, reproducible model for studying Schwann cell interactions with sensory neurons, as well as the myelination process, and its effect on neuronal plasticity and peripheral nerve regeneration. It is also compatible for use in bio-hybrid constructs to reproduce the stretch reflex arc on a chip because the media combination used is the same that we have used previously for motoneurons, muscle, and for neuromuscular junction (NMJ) formation. This work could have application for the study of demyelinating diseases such as diabetes induced peripheral neuropathy and could rapidly translate to a role in the discovery of drugs promoting enhanced peripheral nervous system (PNS) remyelination.     

Oxidative stress perturbs cell proliferation in human K562 cells by modulating protein synthesis and cell cycle

Oxidative stress leads to perturbation of a variety of cellular processes resulting in inhibition of cell proliferation. This study has determined the effect of oxidative stress on protein synthesis in human K562 cells using a hydrophilic peroxyl radical initiator, AAPH and H₂O₂. The results indicated that oxidative stress leads to a significant decrease in the rate of protein synthesis caused due to induced activation as well as expression of the erythroid cell-specific eIF-2α kinase, called the Heme Regulated Inhibitor (HRI). Elevated levels of HRI expression and activity were accompanied by increased lipid peroxidation and decreased cell proliferation. Further, oxidative stress also caused inactivation of p34^cdc2 kinase, thereby arresting cell division leading to apoptosis. Thus, the data provides the mechanism of inhibition of protein synthesis and perturbation of a cell cycle regulatory protein leading to inhibition of cell proliferation in K562 cells during oxidative stress.     

Cholesterol biosensors based on oxygen sensing alginate-silica microspheres

Cholesterol determination in body is important in diagnosis of diseases like coronary heart disease, arteriosclerosis, diabetes, and obstructive jaundice. This research aims at developing fluorimetric cholesterol biosensors based on self-assembled mesoporous alginate-silica (Algilica) microspheres. For preparing the biosensor, Pt-(II)-octaethylporphine (PtOEP; oxygen sensitive metalloporphyrin) dye has been loaded in the Algilica microspheres using the solvent-mediated precipitation method. Cholesterol oxidase (ChOx) was then covalently conjugated to PtOEP/Algilica microspheres using EDC and NHS reagents. PtOEP dye and enzyme encapsulation, activity and stability were then analyzed. Layer-by-layer self-assembly was finally performed using PAH and PSS polyelectrolytes to minimize leaching of the biosensor components. The prepared biosensor exhibited linearity over a range of 0.77-2.5 mM O(2) (K(SV) : 0.097/mM of O(2) ) obtained using from Stern-Volmer plots. The biosensor response to standard cholesterol displayed a linear analytical range from 1.25 to 10 mM of cholesterol with regression coefficient of 0.996 (1.25-3.75 mM), 0.976 (1.25-6 mM), and 0.959 (1.25-10 mM) and response time of 10 min. Thus, the prepared cholesterol biosensor shows great potential in the diagnosis of hypercholesterolemia.     

Detection of novel syntrophic acetate‐oxidizing bacteria from biogas processes by continuous acetate enrichment approaches

To enrich syntrophic acetate‐oxidizing bacteria (SAOB), duplicate chemostats were inoculated with sludge from syntrophic acetate oxidation (SAO)‐dominated systems and continuously supplied with acetate (0.4 or 7.5 g l^?1) at high‐ammonia levels. The chemostats were operated under mesophilic (37°C) or thermophilic (52°C) temperature for about six hydraulic retention times (HRT 28 days) and were sampled over time. Irrespective of temperature, a methane content of 64–69% and effluent acetate level of 0.4–1.0 g l^?1 were recorded in chemostats fed high acetate. Low methane production in the low‐acetate chemostats indicated that the substrate supply was below the threshold for methanization of acetate via SAO. Novel representatives within the family Clostridiales and genus Syntrophaceticus (class Clostridia) were identified to represent putative SAOB candidates in mesophilic and thermophilic conditions respectively. Known SAOB persisted at low relative abundance in all chemostats. The hydrogenotrophic methanogens Methanoculleus bourgensis (mesophilic) and Methanothermobacter thermautotrophicus (thermophilic) dominated archaeal communities in the high‐acetate chemostats. In line with the restricted methane production in the low‐acetate chemostats, methanogens persisted at considerably lower abundance in these chemostats. These findings strongly indicate involvement in SAO and tolerance to high ammonia levels of the species identified here, and have implications for understanding community function in stressed anaerobic processes.     

Cluster Survey Evaluation of a Measles Vaccination Campaign in Jharkhand,India, 2012

IntroductionIndia was the last country in the world to implement a two-dose strategy for measles-containing vaccine (MCV) in 2010. As part of measles second-dose introduction, phased measles vaccination campaigns were conducted during 2010–2013, targeting 131 million children 9 months to <10 years of age. We performed a post-campaign coverage survey to estimate measles vaccination coverage in Jharkhand state.MethodsA multi-stage cluster survey was conducted 2 months after the phase 2 measles campaign occurred in 19 of 24 districts of Jharkhand during November 2011–March 2012. Vaccination status of children 9 months to <10 years of age was documented based on vaccination card or mother’s recall. Coverage estimates and 95% confidence intervals (95% CI) for 1,018 children were calculated using survey methods.ResultsIn the Jharkhand phase 2 campaign, MCV coverage among children aged 9 months to <10 years was 61.0% (95% CI: 54.4–67.7%). Significant differences in coverage were observed between rural (65.0%; 95% CI: 56.8–73.2%) and urban areas (45.6%; 95% CI: 37.3–53.9%). Campaign awareness among mothers was low (51.5%), and the most commonly reported reason for non-vaccination was being unaware of the campaign (69.4%). At the end of the campaign, 53.7% (95% CI: 46.5–60.9%) of children 12 months to <10 years of age received ≥2 MCV doses, while a large proportion of children remained under-vaccinated (34.0%, 95% CI: 28.0–40.0%) or unvaccinated (12.3%, 95% CI: 9.3–16.2%).ConclusionsImplementation of the national measles campaign was a significant achievement towards measles elimination in India. In Jharkhand, campaign performance was below the target coverage of ≥90% set by the Government of India, and challenges in disseminating campaign messages were identified. Efforts towards increasing two-dose MCV coverage are needed to achieve the recently adopted measles elimination goal in India and the South-East Asia region.     

The role of the nucleus pulposus in neutral zone human lumbar intervertebral disc mechanics

To study the effect of denucleation on the mechanical behavior of the human lumbar intervertebral disc through a 2mm incision, two groups of six human cadaver lumbar spinal units were tested in axial compression, axial rotation, lateral bending and flexion/extension after incremental steps of "partial" denucleation. Neutral zone, range of motion, stiffness, intradiscal pressure and energy dissipation were measured; the results showed that the contribution of the nucleus pulposus to the mechanical behavior of the intervertebral disc was more dominant through the neutral zone than at the farther limits of applied loads and moments.     

Do Students See the “Selection” in Organic Evolution? A Critical Review of the Causal Structure of Student Explanations

This paper critically reviews and characterizes the student's causal-explanatory understanding; this is done as a step toward explicating the problematic of evolution education as it concerns the cognitive difficulties in understanding Darwin's theory of natural selection. The review concludes that the student's understanding is fundamentally different from Darwin's, for the student understands evolutionary change as necessary individual transformation caused by the transformative action of various physical and behavioral factors. This is in complete contrast to Darwin's (and even the Darwinian's, for that matter) understanding of evolutionary change as a change caused by accumulative selection. Hence, to understand natural selection, the student has to learn to “see” how the accumulative selection causes evolutionary change.

A convenient one-step synthesis of L-aminotryptophans and improved synthesis of 5-fluorotryptophan

A one-pot biotransformation for the generation of a series of L-aminotryptophans using a readily prepared protein extract containing tryptophan synthase is reported. The extract exhibits remarkable stability upon freeze-drying, and may be stored and used for long periods after its preparation without significant loss of activity.