Search results for "physiology [Biological Transport]"

Absence of malolactic activity is a characteristic of H+-ATPase-deficient mutants of the lactic acid bacterium Oenococcus oeni.

2003

ABSTRACT The lack of malolactic activity in H + -ATPase-deficient mutants of Oenococcus oeni selected previously was analyzed at the molecular level. Western blot experiments revealed a spot at 60 kDa corresponding to the malolactic enzyme only in the parental strain. Moreover, the mleA transcript encoding the malolactic enzyme was not detected by reverse transcription (RT)-PCR analysis of mutants. These results suggest that the malolactic operon was not transcribed in ATPase-deficient mutants. The mleR gene encoding a LysR-type regulatory protein which should be involved in expression of the malolactic genes was described previously for O. oeni . Results obtained in this study show that th…

Let it flow: Morpholino knockdown in zebrafish embryos reveals a pro-angiogenic effect of the metalloprotease meprin alpha2.

2010

BACKGROUND: Meprin metalloproteases are thought to be involved in basic physiological functions such as cell proliferation and tissue differentiation. However, the specific functions of these enzymes are still ambiguous, although a variety of growth factors and structural proteins have been identified as meprin substrates. The discovery of meprins alpha(1), alpha(2) and beta in teleost fish provided the basis for uncovering their physiological functions by gene silencing in vivo. METHODOLOGY/PRINCIPAL FINDINGS: A Morpholino knockdown in zebrafish embryos targeting meprin alpha(1) and beta mRNA caused defects in general tissue differentiation. But meprin alpha(2) morphants were affected more…

Structure of the Zymomonas mobilis respiratory chain: oxygen affinity of electron transport and the role of cytochrome c peroxidase

2014

The genome of the ethanol-producing bacterium Zymomonas mobilis encodes a bd-type terminal oxidase, cytochrome bc 1 complex and several c-type cytochromes, yet lacks sequences homologous to any of the known bacterial cytochrome c oxidase genes. Recently, it was suggested that a putative respiratory cytochrome c peroxidase, receiving electrons from the cytochrome bc 1 complex via cytochrome c 552, might function as a peroxidase and/or an alternative oxidase. The present study was designed to test this hypothesis, by construction of a cytochrome c peroxidase mutant (Zm6-perC), and comparison of its properties with those of a mutant defective in the cytochrome b subunit of the bc 1 complex (Zm…

Engineering a Saccharomyces cerevisiae Wine Yeast That Exhibits Reduced Ethanol Production during Fermentation under Controlled Microoxygenation Cond…

2006

ABSTRACTWe recently showed that expressing an H2O-NADH oxidase inSaccharomyces cerevisiaedrastically reduces the intracellular NADH concentration and substantially alters the distribution of metabolic fluxes in the cell. Although the engineered strain produces a reduced amount of ethanol, a high level of acetaldehyde accumulates early in the process (1 g/liter), impairing growth and fermentation performance. To overcome these undesirable effects, we carried out a comprehensive analysis of the impact of oxygen on the metabolic network of the same NADH oxidase-expressing strain. While reducing the oxygen transfer rate led to a gradual recovery of the growth and fermentation performance, its i…

Untargeted metabolomics of rind essential oils allowed to differentiate two closely related clementine varieties

2021

[EN] Chemical characterization of clementine varieties (Citrus clementina Hort. ex Tan.) essential oils (EO) can lead to variety identification and valorization of their potential use in food and aroma industries. The goal of this study was the chemometric discrimination between two very closely related and morphologically identical clementine varieties, Clemenules (NL) and Clemenpons (PO), based on their rind EO, to identify the differential volatile organic compounds (VOCs) and to determine their antioxidant capacity. EO rind volatile profile was determined by gas chromatography coupled to mass spectrometry in Citrus fruit at different ripening stages grown two independent years in two di…

The L-tartrate/succinate antiporter TtdT (YgjE) of L-tartrate fermentation in Escherichia coli.

2007

ABSTRACT Escherichia coli ferments l -tartrate under anaerobic conditions in the presence of an additional electron donor to succinate. The carrier for l -tartrate uptake and succinate export and its relation to the general C 4 -dicarboxylate carriers DcuA, DcuB, and DcuC were studied. The secondary carrier TtdT, encoded by the ttdT (previously called ygjE ) gene, is required for the uptake of l -tartrate. The ttdT gene is located downstream of the ttdA and ttdB genes, encoding the l -tartrate dehydratase TtdAB. Analysis of mRNA by reverse transcription-PCR showed that ttdA , ttdB , and ttdT are cotranscribed. Deletion of ttdT abolished growth by l -tartrate and degradation of l -tartrate c…

A model study for the progressive disruption of CA1 firing properties during Alzheimer’s disease

2011

Several independent studies show that β-Amyloid (Aβ) peptides accumulation, one of the characteristic hallmark of Alzheimer’s Disease (AD), can affect the normal neuronal activity in different ways causing an increase or a decrease in neuronal membrane excitability. For example, experimental evidence for a negative impact on neuronal membrane in animal models of AD has been obtained in dual patch recordings in rat hippocampal tissue slices, in which Aβ blocked K channels in pyramidal cell dendrites, causing an increase in dendritic membrane excitability. The resulting increased Ca2+ influx and excitoxicity may lead to dendritic degeneration. However, further experimental evidence suggests t…

Oxidative Stress, Inflammation and Endothelial Biomarkers in Arterial Hypertension

2008

An Automata-Based Cardiac Electrophysiology Simulator to Assess Arrhythmia Inducibility

2022

Personalized cardiac electrophysiology simulations have demonstrated great potential to study cardiac arrhythmias and help in therapy planning of radio-frequency ablation. Its application to analyze vulnerability to ventricular tachycardia and sudden cardiac death in infarcted patients has been recently explored. However, the detailed multi-scale biophysical simulations used in these studies are very demanding in terms of memory and computational resources, which prevents their clinical translation. In this work, we present a fast phenomenological system based on cellular automata (CA) to simulate personalized cardiac electrophysiology. The system is trained on biophysical simulations to re…

Hemorheological abnormalities in human arterial hypertension

2014

Blood rheology is impaired in hypertensive patients. The alteration involves blood and plasma viscosity, and the erythrocyte behaviour is often abnormal. The hemorheological pattern appears to be related to some pathophysiological mechanisms of hypertension and to organ damage, in particular left ventricular hypertrophy and myocardial ischemia. Abnormalities have been observed in erythrocyte membrane fluidity, explored by fluorescence spectroscopy and electron spin resonance. This may be relevant for red cell flow in microvessels and oxygen delivery to tissues. Although blood viscosity is not a direct target of antihypertensive therapy, the rheological properties of blood play a role in the…