Temporal changes in digestive enzyme activities in the gastrointestinal tract of European eel (Anguilla anguilla) (Linneo 1758) following feeding

Changes occurring after feeding in the digestive enzyme activities of European eel were investigated to provide some insights into the digestive physiology of this fish. Total and specific proteases, amylase and lipase activities were measured using standard biochemical assays over a 24 h cycle in fed eels, compared to starved ones, under the same rearing conditions. In the gastrointestinal tract of fed eels quantitative changes started 4 h after feeding and continued later on; conversely, in starved eels enzyme activities remained unchanged over time. In fed eels, total and specific protease activities showed an overall increasing trend in the intestine, while in the stomach they progressively decreased to values 22–50% lower than those measured at the pre-feeding time; this behaviour probably reflected the progression of digesta along the intestinal tract. The prolonged secretory response of European eel to food ingestion proved its extended activity in the digestive process.     

Negative modulation of mitochondrial oxidative phosphorylation by epigallocatechin-3 gallate leads to growth arrest and apoptosis in human malignant pleural mesothelioma cells

Increasing evidence reveals a large dependency of epithelial cancer cells on oxidative phosphorylation (OXPHOS) for energy production. In this study we tested the potential of epigallocatechin-3-gallate (EGCG), a natural polyphenol known to target mitochondria, in inducing OXPHOS impairment and cell energy deficit in human epitheliod (REN cells) and biphasic (MSTO-211H cells) malignant pleural mesothelioma (MMe), a rare but highly aggressive tumor with high unmet need for treatment. Due to EGCG instability that causes H₂O₂ formation in culture medium, the drug was added to MMe cells in the presence of exogenous superoxide dismutase and catalase, already proved to stabilize the EGCG molecule and prevent EGCG-dependent reactive oxygen species formation. We show that under these experimental conditions, EGCG causes the selective arrest of MMe cell growth with respect to normal mesothelial cells and the induction of mitochondria-mediated apoptosis, as revealed by early mitochondrial ultrastructure modification, swelling and cytochrome c release. We disclose a novel mechanism by which EGCG induces apoptosis through the impairment of mitochondrial respiratory chain complexes, particularly of complex I, II and ATP synthase. This induces a strong reduction in ATP production by OXPHOS, that is not adequately counterbalanced by glycolytic shift, resulting in cell energy deficit, cell cycle arrest and apoptosis. The EGCG-dependent negative modulation of mitochondrial energy metabolism, selective for cancer cells, gives an important input for the development of novel pharmacological strategies for MMe.     

Precise Gene Editing Preserves Hematopoietic Stem Cell Function following Transient p53-Mediated DNA Damage Response

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A possible transport mechanism for aluminum in biological membranes

The transport mechanism of aluminum in lysosomes extracted from rat liver has been investigated in this paper. The experimental evidence supports the hypothesis that aluminum is transported inside lysosomes in the form of an Al(OH)(3) electroneutral compound, the driving force being the internal acidic pH. This mechanism could help to explain the presence of aluminum in cells in many illnesses.     

A HERG current sustains a cardiac-type action potential in neuroblastoma S cells

From the adrenergic SH-SY5Y human neuroblastoma clone, we isolated a subclone (21S) endowed with a glial-oriented phenotype. At difference from the parental clone, 21S cells responded to depolarizing stimuli with overshooting action potentials, whose repolarization phase was composed of an initial rapid episode, followed by a long-lasting plateau and a slow return to the resting potential (V(REST)). The action potential depolarization phase was sustained by a TTX-sensitive Na(+) current, while the first repolarizing episode was produced by the scanty delayed rectifier potassium current (I(KDR)) expressed in 21S cells. The bulk of repolarization, including the after-hyperpolarization, was sustained by the human eag related (HERG) potassium current (I(HERG)) that also governs V(REST) in 21S cells. This double role of I(HERG), together with the poor expression of I(KDRs), represents a novel finding in electrophysiology, as well as gives a clue to identify a new excitable element of the complex cellular population of neuroblastoma.     

Microglia of teleosts: facing a challenge in neurobiology

This review is concerned with recent literature on teleost fish CNS microglia. It covers not only various aspects of these cells, notably comparing them with mammalian microglia, but also points out the several potentialities neural tissue of teleosts exhibits in neurobiological research. The relationships between neurons and glial cells are considered in fish, aiming at an integrated picture of the complex ways neurons and glia communicate and collaborate in normal and injured neural tissues. In addition, attention has been paid to different teleost models according to their availability, easy maintenance in experimental conditions, possibilities of embryos manipulation and sequenced genome. The recent setting up of successful protocols for fish glia and mixed neuron-glia cultures, together with the molecular facilities offered from genome knowledge, should provide a new boost to studies about microglia and neuron-microglia relationships.     

Two different pathways are involved in peroxynitrite-induced senescence and apoptosis of human erythrocytes

CO(2) changes the biochemistry of peroxynitrite basically in two ways: (i) nitrating species is the CO(3)(-) / ()NO(2) radical pair, and (ii) peroxynitrite diffusion distance is significantly reduced. For peroxynitrite generated extracellularly this last effect is particularly dramatic at low cell density because CO(3)(-) and ()NO(2) are short-lived and decay mostly in the extracellular space or at the cell surface/membrane. This study was aimed to distinguish between peroxynitrite-induced extra- and intracellular modifications of red blood cells (RBC). Our results show that at low cell density and in the presence of CO(2) peroxynitrite induced the oxidation of surface thiols, the formation of 3-nitrotyrosine and DMPO-RBC adducts, and the down-regulation of glycophorins A and C (biomarkers of senescence). Reactivation of glycolysis reversed only the oxidation of surface thiols. Without CO(2) peroxynitrite also induced the oxidation of hemoglobin and glutathione, the accumulation of lactate, a decrease in ATP, the clustering of band 3, the externalization of phosphatidylserine, and the activation of caspases 8 and 3 (biomarkers of apoptosis). The latter biomarkers were all reversed by reactivation of glycolysis. We hypothesize that cell senescence could (generally) be derived by irreversible radical-mediated oxidation of membrane targets, while the appearance of apoptotic biomarkers could be bolstered by oxidation of intracellular targets. These results suggest that, depending on extracellular homolysis or diffusion to the intracellular space, peroxynitrite prompts RBCs toward either senescence or apoptosis through different oxidation mechanisms.     

Abscisic Acid Transport in Human Erythrocytes

Abscisic acid (ABA) is a plant hormone involved in the response to environmental stress. Recently, ABA has been shown to be present and active also in mammals, where it stimulates the functional activity of innate immune cells, of mesenchymal and hemopoietic stem cells, and insulin-releasing pancreatic β-cells. LANCL2, the ABA receptor in mammalian cells, is a peripheral membrane protein that localizes at the intracellular side of the plasma membrane. Here we investigated the mechanism enabling ABA transport across the plasmamembrane of human red blood cells (RBC). Both influx and efflux of [³H]ABA occur across intact RBC, as detected by radiometric and chromatographic methods. ABA binds specifically to Band 3 (the RBC anion transporter), as determined by labeling of RBC membranes with biotinylated ABA. Proteoliposomes reconstituted with human purified Band 3 transport [³H]ABA and [³⁵S]sulfate, and ABA transport is sensitive to the specific Band 3 inhibitor 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid. Once inside RBC, ABA stimulates ATP release through the LANCL2-mediated activation of adenylate cyclase. As ATP released from RBC is known to exert a vasodilator response, these results suggest a role for plasma ABA in the regulation of vascular tone.     

Selection dynamic of Escherichia coli host in M13 combinatorial peptide phage display libraries

Phage display relies on an iterative cycle of selection and amplification of random combinatorial libraries to enrich the initial population of those peptides that satisfy a priori chosen criteria. The effectiveness of any phage display protocol depends directly on library amino acid sequence diversity and the strength of the selection procedure. In this study we monitored the dynamics of the selective pressure exerted by the host organism on a random peptide library in the absence of any additional selection pressure. The results indicate that sequence censorship exerted by Escherichia coli dramatically reduces library diversity and can significantly impair phage display effectiveness.