Parabiosis in Mice: A Detailed Protocol

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 1864¹, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival². In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.     

Guanosine Exerts Neuroprotective Effect in an Experimental Model of Acute Ammonia Intoxication

The nucleoside guanosine (GUO) increases glutamate uptake by astrocytes and acts as antioxidant, thereby providing neuroprotection against glutamatergic excitotoxicity, as we have recently demonstrated in an animal model of chronic hepatic encephalopathy. Here, we investigated the neuroprotective effect of GUO in an acute ammonia intoxication model. Adult male Wistar rats received an intraperitoneal (i.p.) injection of vehicle or GUO 60 mg/kg, followed 20 min later by an i.p. injection of vehicle or 550 mg/kg of ammonium acetate. Afterwards, animals were observed for 45 min, being evaluated as normal, coma (i.e., absence of corneal reflex), or death status. In a second cohort of rats, video-electroencephalogram (EEG) recordings were performed. In a third cohort of rats, the following were measured: (i) plasma levels of glucose, transaminases, and urea; (ii) cerebrospinal fluid (CSF) levels of ammonia, glutamine, glutamate, and alanine; (iii) glutamate uptake in brain slices; and (iv) brain redox status and glutamine synthetase activity in cerebral cortex. GUO drastically reduced the lethality rate and the duration of coma. Animals treated with GUO had improved EEG traces, decreased CSF levels of glutamate and alanine, lowered oxidative stress in the cerebral cortex, and increased glutamate uptake by astrocytes in brain slices compared with animals that received vehicle prior to ammonium acetate administration. This study provides new evidence on mechanisms of guanine-derived purines in their potential modulation of glutamatergic system, contributing to GUO neuroprotective effects in a rodent model of by acute ammonia intoxication.     

Spectroscopic studies of interaction between CuO nanoparticles and bovine serum albumin

Recently, the great interests in manufacturing and application of metal oxide nanoparticles in commercial and industrial products have led to focus on the potential impact of these particles on biomacromolecules. In the present study, the interaction of copper oxide (CuO) nanoparticles with bovine serum albumin (BSA) was studied by spectroscopic techniques. The zeta potential value for BSA and CuO nanoparticles with average diameter of around 50 nm at concentration of 10 μM in the deionized (DI) water were ?5.8 and ?22.5 mV, respectively. Circular dichroism studies did not show any changes in the content of secondary structure of the protein after CuO nanoparticles interaction. Fluorescence data revealed that the fluorescence quenching of BSA by CuO nanoparticles was the result of the formed complex of CuO nanoparticles – BSA. Binding constants and other thermodynamic parameters were determined at three different temperatures. The hydrogen bond interactions are the predominant intermolecular forces to stabilize the CuO nanoparticle – BSA complex. This study provides important insight into the interaction of CuO nanoparticles with proteins, which may be of importance for further application of these nanoparticles in biomedical applications.     

An airtight approach to the inebriometer

The mechanism by which inhaled anesthetics work is not fully understood, although they have been extensively used. Much research has been done showing the likelihood that there is more than one pathway or mechanism of action. A long-term goal of our laboratory is to decipher these mechanisms using Drosophila melanogaster, an excellent model organism for this purpose. In order to do this, we have modified and constructed an apparatus called the inebriometer to quantitatively analyze the response of flies to inhaled anesthetics. While the inebriometer is not new to the fly community, our updated design provides a relatively low-labor, high-throughput means for performing screens in search of genes involved in the anesthetic mechanism. Here we describe our construction of an airtight inebriometer that we have designed for this purpose. We also provide data that validates this apparatus and establishes a procedure for its use.     

Complicated Role of Exercise in Modulating Memory: A Discussion of the Mechanisms Involved

Neurochemical Research - Evidence has shown the beneficial effects of exercise on learning and memory. However, many studies have reported controversial results, indicating that exercise can impair...     

Application of gas diffusion electrodes in bioeconomy: An update

The transition of today's fossil fuel based chemical industry toward sustainable production requires improvement of established production processes as well as development of new sustainable and bio-based synthesis routes within a circular economy. Thereby, the combination of electrochemical and biotechnological advantages in such routes represents one important keystone. For the electrochemical generation of reactants from gaseous substrates such as O₂ or CO₂, gas diffusion electrodes (GDE) represent the electrodes of choice since they overcome solubility-based mass transport limitations. Within this article, we illustrate the architecture, function principle and fabrication of GDE. We highlight the application of GDE for conversion of CO₂ using abiotic catalysts for subsequent biosynthesis as well as the application of microbial catalysts at GDE for CO₂ conversion. The reduction of oxygen at GDE is summarized for the application of oxygen depolarized cathodes in microbial fuel cells and generation of H₂O₂ to drive enzymatic reactions. Finally, engineering aspects such as scale-up and the modeling of GDE-based processes are described. This review presents an update on the application of GDE in bio-based production systems and emphasizes their large potential for sustainable development of new pathways in bioeconomy.