Search results for "RICH"

O2 as the regulatory signal for FNR-dependent gene regulation in Escherichia coli

1996

With an oxystat, changes in the pattern of expression of FNR-dependent genes from Escherichia coli were studied as a function of the O2 tension (pO2) in the medium. Expression of all four tested genes was decreased by increasing O2. However, the pO2 values that gave rise to half-maximal repression (pO(0.5)) were dependent on the particular promoter and varied between 1 and 5 millibars (1 bar = 10(5) Pa). The pO(0.5) value for the ArcA-regulated succinate dehydrogenase genes was in the same range (pO(0.5) = 4.6 millibars). At these pO2 values, the cytoplasm can be calculated to be well supplied with O2 by diffusion. Therefore, intracellular O2 could provide the signal to FNR, suggesting that…

The Friedreich's Ataxia protein frataxin modulates DNA base excision repair in prokaryotes and mammals

2010

DNA-repair mechanisms enable cells to maintain their genetic information by protecting it from mutations that may cause malignant growth. Recent evidence suggests that specific DNA-repair enzymes contain ISCs (iron–sulfur clusters). The nuclearencoded protein frataxin is essential for the mitochondrial biosynthesis of ISCs. Frataxin deficiency causes a neurodegenerative disorder named Friedreich's ataxia in humans. Various types of cancer occurring at young age are associated with this disease, and hence with frataxin deficiency. Mice carrying a hepatocyte-specific disruption of the frataxin gene develop multiple liver tumours for unresolved reasons. In the present study, we show that frata…

O2-sensing and O2-dependent gene regulation in facultatively anaerobic bacteria.

1995

Availability of O2 is one of the most important regulatory signals in facultatively anaerobic bacteria. Various two- or one-component sensor/regulator systems control the expression of aerobic and anaerobic metabolism in response to O2. Most of the sensor proteins contain heme or Fe as cofactors that interact with O2 either by binding or by a redox reaction. The ArcA/ArcB regulator of aerobic metabolism in Escherichia coli may use a different sensory mechanism. In two-component regulators, the sensor is located in the cytoplasmic membrane, whereas one-component regulators are located in the cytoplasm. Under most conditions, O2 can readily reach the cytoplasm and could provide the signal in …

Stimulation of Fe-S cluster insertion into apoFNR by Escherichia coli glutaredoxins 1, 2 and 3 in vitro.

2004

Abstract The oxygen sensor fumarate nitrate reductase regu-lator (FNR) of Escherichia coli contains in the active (anaerobic)state a [4Fe–4S] 2þ cluster which is lost after exposure to O 2 .Inaerobically prepared apoFNR, or in FNR obtained by treatmentof [4Fe–4S] FNR with O 2 in vitro, intramolecular cysteinedisulfides are found, including the cysteine residues which serveas ligands for the Fe–S cluster. It is shown here that thereconstitution of [4Fe–4S] FNR from this form of aerobicapoFNR was preceded by a long lag phase when glutathione wasused as the reducing agent. Addition of E. coli glutaredoxins(Grx) 1, 2 or 3 decreased the lag phase greatly and stimulatedthe reconstitution rate slig…

The oxygen-responsive transcriptional regulator FNR ofEscherichia coli : the search for signals and reactions

1997

The FNR (fumarate and nitrate reductase regulation) protein of Escherichia coli is an oxygen-responsive transcriptional regulator required for the switch from aerobic to anaerobic metabolism. In the absence of oxygen, FNR changes from the inactive to the active state. The sensory and the regulatory functions reside in separate domains of FNR. The sensory domain contains a Fe-S cluster, which is of the [4Fe-4S]2+ type under anaerobic conditions. It is suggested that oxygen is supplied to the cytoplasmic FNR by diffusion and inactivates FNR by direct interaction. Reactivation under anoxic conditions requires cellular reductants. In vitro, the Fe-S cluster is converted to a [3Fe-4S]+ or a [2Fe…

Study and development of innovative measurement methods and systems for anti-islanding protection in smart grids

2014

Un metodo ibrido per il riconoscimento dell'islanding in reti di media e bassa tensione in presenza di generazione distribuita

2013

Additions to knowledge of the biodiversity of benthic hydroids (Cnidaria: Hydrozoa) in the Balleny Islands (Antarctica)

2021

The Balleny Islands, an isolated archipelago located 240 km off the coast of Victoria Land (East Antarctica), are separated from the Antarctic continental shelf by waters more than 2000 m deep. The benthic hydroid fauna of these islands is little known, with only 25 species reported so far. The present study contributes to a better knowledge of the benthic hydrozoans inhabiting this archipelago by studying a small collection held at the National Institute of Water and Atmospheric Research Invertebrate Collection at Wellington, New Zealand. Sixteen species of benthic hydroids were found in the collection, belonging to nine families and 12 genera of Leptothecata. Kirchenpaueriidae and Oswalde…

Evaluation of Psychometric and Linguistic Properties of the Italian Adolescent Pain Assessment Scales: A Systematic Review

2018

Introduction: Adolescents’ pain experiences are complex and multidimensional, and evaluating pain only from a sensory and affective point of view may be in many instances limiting and inadequate; this is the reason why it is of paramount importance to identify the tools which can better assess the pain experienced by young patients. A person-oriented approach is highly encouraged, as it may better investigate the cognitive and behavioral development typical of this age group. The aim of this review paper is to describe the available tools which are able to adequately assess pain intensity in adolescents, in particular those validated in Italian. Methods: We conducted a systematic review usi…

The Dark Trienium: Valencia, 1389-1391. Unrest coinciding with an assault on the Jewish district

2012

Estudio de base documental sobre el auge del antijudaísmo desde 1371 y el asalto a la judería de Valencia en julio de 1391, al poco tiempo de su ampliación. Sitúa el hecho en el contexto de las tensiones políticas en la Corona de Aragón y en la ciudad, donde se enfrentaban sendos bandos: actuaciones entre 1375 y 1392 del inquisidor Nicolau Eimeric (Directorium inquisitorum) contra herejes y su condena de obras de Ramon Llull. Cortes de 1388-1389. Guerras en el ámbito pirenaico en 1390. Políticas de abastecimiento y defensa de la ciudad de Valencia y oposición de villas y nobles del reino al municipio de la capital, que arma una milicia montada en mayo de 1391. Represión de maleantes y medid…