Iodine uptake in brown seaweed exposed to radioactive liquid discharges from the reprocessing plant of ORANO La Hague.

Iodine-129 is present in controlled liquid radioactive waste routinely released in seawater by the ORANO nuclear fuel reprocessing plant in La Hague (Normandy, France). Brown algae are known for their exceptional ability to concentrate iodine from seawater. They also potentially emit volatile iodine compounds in response to various stresses, such as during emersion at low tide.

A comprehensive assessment of two-decade radioactivity monitoring around the Channel Islands.

The Channel Islands are located in the Normand-Breton Gulf (NBG), in the mid-part of the English Channel (France, Normandy). In the northern part, off Cap La Hague, controlled amounts of radioactive liquid waste are discharged by the ORANO La Hague nuclear fuel reprocessing plant (RP). Radionuclides were monitored in the NBG to assess the dispersion of radioactive discharges from the RP in the marine environment.

A global database of nitrogen and phosphorus excretion rates of aquatic animals.

Animals can be important in modulating ecosystem-level nutrient cycling, although their importance varies greatly among species and ecosystems. Nutrient cycling rates of individual animals represent valuable data for testing the predictions of important frameworks such as the Metabolic Theory of Ecology (MTE) and ecological stoichiometry (ES). They also represent an important set of functional traits that may reflect both environmental and phylogenetic influences.

The VATO project: Development and validation of a dynamic transfer model of tritium in grassland ecosystem.

In this paper, a dynamic compartment model with a high temporal resolution has been investigated to describe tritium transfer in grassland ecosystems exposed to atmospheric H releases from nuclear facilities under normal operating or accidental conditions. TOCATTA-χ model belongs to the larger framework of the SYMBIOSE modelling and simulation platform that aims to assess the fate and transport of a wide range of radionuclides in various environmental systems. In this context, the conceptual and mathematical models of TOCATTA-χ have been designed to be relatively simple, minimizing the number of compartments and input parameters required.

The VATO project: An original methodology to study the transfer of tritium as HT and HTO in grassland ecosystem.

Tritium (H) is mainly released into the environment by nuclear power plants, military nuclear facilities and nuclear reprocessing plants. The construction of new nuclear facilities in the world as well as the evolution of nuclear fuel management might lead to an increase of H discharges from the nuclear industry. The VATO project was set up by IRSN (Institut de Radioprotection et de Sûreté Nucléaire) and EDF (Electricité de France) to reduce the uncertainties in the knowledge about transfers of H from an atmospheric source (currently releasing HT and HTO) to a grassland ecosystem.

On the use of 31P NMR for the quantification of hydrosoluble phosphorus-containing compounds in coral host tissues and cultured zooxanthellae.

(31)P Nuclear Magnetic Resonance (NMR) was assessed to investigate the phosphorus-containing compounds present in the tissues of the scleractinian coral Stylophora pistillata as well as of cultured zooxanthellae (CZ). Results showed that phosphorus-containing compounds observed in CZ were mainly phosphate and phosphate esters. Phosphate accounted for 19 ± 2% of the total phosphorus compounds observed in CZ maintained under low P-levels (0.

Near-field krypton-85 measurements in stable meteorological conditions around the AREVA NC La Hague reprocessing plant: estimation of atmospheric transfer coefficients.

The aim of this work was to study the near-field dispersion of (85)Kr around the nuclear fuel reprocessing plant at La Hague (AREVA NC La Hague - France) under stable meteorological conditions. Twenty-two (85)Kr night-time experimental campaigns were carried out at distances of up to 4 km from the release source. Although the operational Gaussian models predict for these meteorological conditions a distance to plume touchdown of several kilometers, we almost systematically observed a marked ground signal at distances of 0.

Coral uptake of inorganic phosphorus and nitrogen negatively affected by simultaneous changes in temperature and pH.

The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO(2) on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata.

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata.

Several untested aspects of the regulation of inorganic nutrient uptake were examined using nutrient depletion experiments with the symbiotic coral Stylophora pistillata. The total inhibition of phosphate uptake in artificial seawater lacking sodium indicates the involvement of a sodium/phosphate symporter for the uptake of phosphate across host membranes. Addition of ammonium or nitrate (up to 6.

HIF and reactive oxygen species regulate oxidative phosphorylation in cancer.

A decrease in oxidative phosphorylation (OXPHOS) is characteristic of many cancer types and, in particular, of clear cell renal carcinoma (CCRC) deficient in von Hippel-Lindau (vhl) gene. In the absence of functional pVHL, hypoxia-inducible factor (HIF) 1-alpha and HIF2-alpha subunits are stabilized, which induces the transcription of many genes including those involved in glycolysis and reactive oxygen species (ROS) metabolism. Transfection of these cells with vhl is known to restore HIF-alpha subunit degradation and to reduce glycolytic genes transcription.

New evidence of a mitochondrial genetic background paradox: impact of the J haplogroup on the A3243G mutation.

Background: The A3243G mutation in the tRNALeu gene (UUR), is one of the most common pathogenic mitochondrial DNA (mtDNA) mutations in France, and is associated with highly variable and heterogeneous disease phenotypes. To define the relationships between the A3243G mutation and mtDNA backgrounds, we determined the haplogroup affiliation of 142 unrelated French patients - diagnosed as carriers of the A3243G mutation - by control-region sequencing and RFLP survey of their mtDNAs.

Results: The analysis revealed 111 different haplotypes encompassing all European haplogroups, indicating that the 3243 site might be a mutational hot spot.

Clonal expansion of mutated mitochondrial DNA is associated with tumor formation and complex I deficiency in the benign renal oncocytoma.

Mutations in mitochondrial DNA (mtDNA) are frequent in cancers but it is not yet clearly established whether they are modifier events involved in cancer progression or whether they are a consequence of tumorigenesis. Here we show a benign tumor type in which mtDNA mutations that lead to complex I (CI) enzyme deficiency are found in all tumors and are the only genetic alteration detected. Actually renal oncocytomas are homogeneous tumors characterized by dense accumulation of mitochondria and we had found that they are deficient in electron transport chain complex I (CI, NADH-ubiquinone oxidoreductase).

Actuality of Warburg's views in our understanding of renal cancer metabolism.

More than 50 years ago, Warburg proposed that the shift in glucose metabolism from oxidative phosphorylation (OXPHOS) to glycolysis occurring in spite of an adequate oxygen supply was at the root of cancer. This hypothesis often disregarded over the following years has recently stirred up much interest due to progress made in cancer genetics and proteomics. Studies related to renal cancers have been particularly informative to understand how abnormal use of glucose and decrease in OXPHOS are linked to cell proliferation in tumors.

Mitochondria and reactive oxygen species in renal cancer.

In most cancer cells, the ATP necessary for survival and proliferation is derived from glycolysis rather than from oxidative phosphorylations (OXPHOS) even when oxygen supply would be adequate to sustain them. This phenomenon, named "aerobic glycolysis" by Warburg many years ago, can now be explained by a mechanism up-regulating the expression of genes involved in glucose transport, glucose metabolism, lactate formation and exit from the cell. In clear cell renal carcinoma, this mechanism is due to the stabilization of the hypoxia-inducible transcription factor HIF occurring when the tumor suppressor gene vhl is invalidated.

Mitochondrial disorders in renal tumors.

As early as 1930, Warburg discovered that metabolic alterations were associated with carcinogenesis and that cancer cells fermented even in the presence of oxygen using glycolysis to fulfill their energy needs, though less efficiently than with respiration. The kidney requiring a very active energy production for its pumping functions has a high mitochondrial activity. Kidney tumors can exist either in relatively benign forms, as for example, in oncocytomas that are crowded with mitochondria or in very aggressive forms such as in clear cell renal carcinomas that exhibit strongly down-regulated mitochondrial activities.

Inhibition of cytochrome c oxidase subunit 4 precursor processing by the hypoxia mimic cobalt chloride.

Cobalt is often used as a hypoxia mimic in cell culture, because it stabilizes the alpha subunits of the transcription factor, HIF (hypoxia-inducible factor). We have previously shown that HIF stabilization due to a deficiency of the von Hippel Lindau protein (pVHL) in clear cell renal carcinoma (CRCC) was correlated to a down-regulation of oxidative phosphorylation. To better understand this mechanism, we have used CoCl2 in CRCC expressing stably transfected vhl.

Physiological oxygenation status is required for fully differentiated phenotype in kidney cortex proximal tubules.

Hypoxia has been suspected to trigger transdifferentiation of renal tubular cells into myofibroblasts in an epithelial-to-mesenchymal transition (EMT) process. To determine the functional networks potentially altered by hypoxia, rat renal tubule suspensions were incubated under three conditions of oxygenation ranging from normoxia (lactate uptake) to severe hypoxia (lactate production). Transcriptome changes after 4 h were analyzed on a high scale by restriction fragment differential display.

Pathogenicity of missense mutations in SURF1 deficiency inducing the Leigh syndrome. Importance in diagnosis.

Leigh syndrome with cytochrome oxidase (COX) deficiency has been associated with SURF1 mutations. For patient diagnosis, distinction between neutral polymorphisms and pathogenic missense SURF1 mutations in Leigh syndrome is essential. We show that several missense SURF1 mutations did not allow a stable protein to be expressed.

A Russian family of Slavic origin carrying mitochondrial DNA with a 9-bp deletion in region V and a long C-stretch in D-loop.

A 9-bp deletion first described in the mitochondrial DNA (mtDNA) for East Asian, Polynesian or Indian American populations of the B haplogroup is now discovered in Slavs. The Russian family carrying that deletion belongs to a new branch of the T haplogroup as deduced from D-loop sequence and haplogroup-specific restriction fragment length polymorphism analysis. One family member had a Kearns-Sayre syndrome with a 5.

A new role for the von Hippel-Lindau tumor suppressor protein: stimulation of mitochondrial oxidative phosphorylation complex biogenesis.

Although mitochondrial deficiency in cancer has been described by Warburg, many years ago, the mechanisms underlying this impairment remain essentially unknown. Many types of cancer cells are concerned and, in particular, clear cell renal carcinoma (CCRC). In this cancer, the tumor suppressor gene, VHL (von Hippel-Lindau factor) is invalidated.

Natural antisense transcripts of HIF-1alpha are conserved in rodents.

A natural antisense transcript (aHIF), which sequence is strictly complementary to the 3' untranslated region (3'UTR) of HIF-1alpha mRNA, has been identified in human and shown to be overexpressed in renal carcinomas. We searched for aHIF in different rodent tissues. Two candidate expressed sequence tag (EST) were identified in silico and their PCR products (1.

Significance of respirasomes for the assembly/stability of human respiratory chain complex I.

We showed that the human respiratory chain is organized in supramolecular assemblies of respiratory chain complexes, the respirasomes. The mitochondrial complexes I (NADH dehydrogenase) and III (cytochrome c reductase) form a stable core respirasome to which complex IV (cytochrome c oxidase) can also bind. An analysis of the state of respirasomes in patients with an isolated deficiency of single complexes provided evidence that the formation of respirasomes is essential for the assembly/stability of complex I, the major entry point of respiratory chain substrates.

Mitochondrial membrane potential and ATP production in primary disorders of ATP synthase.

Studies of fibroblasts with primary defects in mitochondrial ATP synthase (ATPase) due to heteroplasmic mtDNA mutations in the ATP6 gene, affecting protonophoric function or synthesis of subunit a, show that at high mutation loads, mitochondrial membrane potential DeltaPsi(m) at state 4 is normal, but ADP-induced discharge of DeltaPsi(m) is impaired and ATP synthesis at state 3-ADP is decreased. Increased DeltaPsi(m) and low ATP synthesis is also found when the ATPase content is diminished by altered biogenesis of the enzyme complex. Irrespective of the different pathogenic mechanisms, elevated DeltaPsi(m) in primary ATPase disorders could increase mitochondrial production of reactive oxygen species and decrease energy provision.

GUG is an efficient initiation codon to translate the human mitochondrial ATP6 gene.

A maternally inherited and practically homoplasmic mitochondrial (mtDNA) mutation, 8527A>G, changing the initiation codon AUG into GUG, normally coding for a valine, was observed in the ATP6 gene encoding the ATPase subunit a. No alternate Met codon could replace the normal translational initiator. The patient harboring this mutation exhibited clinical symptoms suggesting a mitochondrial disease but his mother who carried the same mtDNA mutation was healthy.

Functional alteration of cytochrome c oxidase by SURF1 mutations in Leigh syndrome.

Subacute necrotising encephalomyopathy (Leigh syndrome) due to cytochrome c oxidase (COX) deficiency is often caused by mutations in the SURF1 gene, encoding the Surf1 protein essential for COX assembly. We have investigated five patients with different SURF1 mutations resulting in the absence of Surf1 protein. All of them presented with severe and generalised COX defect.