Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The nature of factors governing the tempo and mode of protein evolution is a fundamental issue in evolutionary biology. Specifically, whether or not interactions between different sites, or epistasis, are important in directing the course of evolution became one of the central questions. Several recent reports have scrutinized patterns of long-term protein evolution claiming them to be compatible only with an epistatic fitness landscape. However, these claims have not yet been substantiated with a formal model of protein evolution. Here, we formulate a simple covarion-like model of protein evolution focusing on the rate at which the fitness impact of amino acids at a site changes with time. We then apply the model to the data on convergent and divergent protein evolution to test whether or not the incorporation of epistatic interactions is necessary to explain the data. We find that convergent evolution cannot be explained without the incorporation of epistasis and the rate at which an amino acid state switches from being acceptable at a site to being deleterious is faster than the rate of amino acid substitution. Specifically, for proteins that have persisted in modern prokaryotic organisms since the last universal common ancestor for one amino acid substitution approximately ten amino acid states switch from being accessible to being deleterious, or vice versa. Thus, molecular evolution can only be perceived in the context of rapid turnover of which amino acids are available for evolution.
ISSN: 0737-4038

hal-01544755
https://hal.archives-ouvertes.fr/hal-01544755
DOI : 10.1093/molbev/msu318

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Strombus gigas and Strombus pugilis are threatened species and aquaculture represents a good alternative solution to the fishing. In this study, we highlighted the intracellular digestion process in the digestive gland of two Strombidae species, S. gigas and Strombus pugilis, by the cytochemical characterization of two lysosomal enzymes: acid phosphatase and arylsulfatase. In order to check the efficiency of artificial food digestion, we onducted the characterization on freshly collected, tarved and artificially fed individuals of S. pugilis. TEM observations of digestive gland sections from freshly collected individuals of both species revealed the resence of acid phosphatase and arylsulfatase activity mostly located in the apical third of digestive cells. Both enzymes were also detected in artificially fed individuals. In response to the starvation, acid phosphatase is not produced anymore by digestive cells, while arylsulfatase is still present. To our knowledge, this is the first cytochemical validation of intracellular digestion of artificial food in Strombidae. This study highlights the intracellular digestion of artificial food developed for Strombidae aquaculture. Moreover, we have shown that the lysosomal activity could be used as a feed index.
ISSN: 1059-910X

hal-00743013
https://hal.univ-antilles.fr/hal-00743013
DOI : 10.1002/jemt.22074

Éditeur(s) : HAL CCSD
Résumé : International audience
Alkaloids extract of Aspidosperma album was tested as corrosion inhibitor for C38 steel in 1 M HCl by using polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves indicated that the plant extract behaves as mixed-type inhibitors. Impedance measurements showed that the double-layer capacitance decreased and charge-transfer resistance increased with increase in the inhibitors concentration and hence increasing in inhibition efficiency. The effect of temperature on the corrosion behavior of C38 steel in 1 M HCl with and without addition of plant extract was studied in the temperature range 25 – 55 °C. The adsorption of the inhibitor molecules was in accordance with the Langmuir adsorption isotherm. The results obtained show that this plant extract could serve as an effective inhibitor for the corrosion of C38 steel in hydrochloric acid.
International journal of electrochemical science

hal-01097107
https://hal-agroparistech.archives-ouvertes.fr/hal-01097107

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In order to perform a human and ecological risk assessment of pharmaceutical products (PPs) in natural waters, it is necessary to accurately quantify a broad variety of PPs at low concentrations. Although numerous currently implemented analytical methodologies, less is known about the preservation of PPs in natural water samples within the period before analysis (holding time, storage conditions). This paper is the first literature review about the stability of PPs in natural waters (surface and groundwaters) during sample storage. The current work focuses on a comparison of the performances of the available preservation techniques (filtration, container materials, storage temperature, preservative agents, etc.) for PPs in samples. All 58 reviewed PPs may be successfully stabilized during 7 days in surface waters by at least one appropriate methodology regarding temperature, acidic and non-acidic preservatives. When temperature is not a sufficient preservation parameter f! or some PPs (hormones and fluoxetine) its combination with the addition of chemical agents into the samples may prolong the integrity of the PPs during storage in surface water. There is a strong need to use standard protocols to assess and compare the stability of PPs in environmental water matrices during storage as well as during analytical preparation or analysis (European criteria 2002/657/EC). Since the stability of PPs during sample storage is a critical parameter that could call into question the quality of the data provided for the concentrations, the design of stability studies should rigorously take into account all critical parameters that could impact the concentrations of the PPs with time.
Talanta

insu-00839186
https://hal-insu.archives-ouvertes.fr/insu-00839186
DOI : 10.1016/j.talanta.2013.01.042

Éditeur(s) : HAL CCSD Oldendorf/Luhe
Résumé : International audience
Large filamentous sulfur-oxidizing bacteria belonging to the Beggiatoacae family can cover large portions of shallow marine sediments surrounding mangroves in Guadeloupe (French West Indies). In order to assess the importance of Beggiatoa mats as an infaunal food source, observations were conducted of the area within mats and at increasing distances from mats. We used natural isotopic compositions and a C-13 enrichment study. Both revealed an ingestion of bacterial mats by associated meiofauna, dominated by rotifers and to a smaller extent by small polychaetes and nematodes. Compared to adjacent sites, sediment covered by bacterial mats presented a higher abundance of diatoms, whereas the total biomass of bacteria did not vary. This constant bacterial abundance suggests that the proportion of organic matter represented by sulfur bacteria is limited compared to the fraction of total bacteria. There was no significant difference in infaunal abundance in mats, suggesting that the availability of this chemosynthetic food resource had a limited local effect. Grazers presented a delta C-13 value increasing with distance from the mat. However, isotopic composition of phospholipid-derived fatty acids specific for diatoms and bacteria revealed that this change is related to modifications of delta C-13 dietary components rather than to changes in diet composition. These complementary methods revealed that the occurrence of sulfur-oxidizing bacterial mats does not necessarily affect grazer abundance and importance of bacteria in their diet. Despite its wide occurrence, Beggiatoa mats would consequently have a minor influence on the structure of the mangrove food web.
ISSN: 0171-8630

hal-01545912
https://hal.archives-ouvertes.fr/hal-01545912
DOI : 10.3354/meps11035

Éditeur(s) : HAL CCSD Awwa American Water Works Association
Résumé : International audience
A three-year study was conducted on the occurrence of disinfection by-products (DBPs) - trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles - in drinking water of regions of Europe where epidemiology studies were being carried out. Thirteen systems in six countries (i.e., Italy, France, Greece, Lithuania, Spain, United Kingdom) were sampled. Typically chlorinated DBPs dominated. However, in most of Catalonia (Spain) and in Heraklion (Greece), brominated DBPs dominated. The degree of bromine incorporation into the DBP classes was in general similar among them. This is important, as brominated DBPs are a greater health concern. In parts of Catalonia, the reported levels of tribromoacetic acid were higher than in other parts of the world. In some regions, the levels of HAAs tended to be peaked in concentration in a different time period than when the levels of THMs peaked. In most epidemiology studies, THMs are used as a surrogate for other halogenated DBPs. This study provides exposure assessment information for epidemiology studies. © 2016 American Water Works Association.
ISSN: 0003-150X

hal-01406069
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01406069
DOI : 10.5942/jawwa.2016.108.0152

Éditeur(s) : HAL CCSD
Résumé : Food-grade dairy propionibacteria release beneficial short chain fatty acids (SCFAs), folic acid and cobalamin. They induce apoptosis via the mitochondrial death pathway. We investigated their synergy with drugs used in gastric and colorectal cancer.Fermented milk containing propionibacteria and SCFAS acetate and propionate, as well as its cell-free supernatant, induced apoptosis in gastric HGT-1 and colic HT-29. Characterization of cells revealed apoptosis induction evidenced by chromatin condensation, DNA laddering, emergence of a subG1 population, phosphatidylserine exposure at the plasma membrane outer leaflet and cytochrome c release. Interestingly, the fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy, camptothecin and TRAIL (TNF Related Apoptosis Inducing Ligand).These results open new perspectives in the field of colon cancer cells prevention and/or treatment. Such a fermented product, or the propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments.
Les bactéries propioniques laitières produisent des acides gras volatils (AGV), acide folique et cobalamine, composés bénéfiques. Elles induisent l’apoptose via la voie mitochondriale. Nous avons recherché leur synergie avec des drogues utilisées dans le cancer gastrique ou colique.Un lait fermenté contenant des bactéries propioniques et les AGVs propionate et acétate a induit l’apoptose de cellules gastriques HGT-1 et coliques HT-29. L’étude des cellules a révélé l’induction de l’apoptose : condensation de la chromatine, fragmentation de l’ADN, l’émergence d’une population subG1, l’externalisation des phosphatidylserines et le relargage du cytochrome c. De manière intéressante, le lait fermenté a potentialisé les effets cytotoxiques de molécules utilisées en chimiothérapie, camptothécine et TRAIL (TNF Related Apoptosis Inducing Ligand).Ces résultats ouvrent de nouvelles perspectives dans le domaine du traitement ou de la prévention des cancers digestifs. Un tel produit fermenté, ou les propionibactéries seules, pourrait être proposé comme supplément alimentaire pour augmenter l’efficacité de traitements anti-cancéreux.
5. Colloque Intenational Molécules & Ingrédients Santé
Quimper, France

hal-01204307
https://hal.archives-ouvertes.fr/hal-01204307
PRODINRA : 261444

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
DNase I requires Ca²+ and Mg²+ for hydrolyzing double-stranded DNA. However, the number and the location of DNase I ion-binding sites remain unclear, as well as the role of these counter-ions. Using molecular dynamics simulations, we show that bovine pancreatic (bp) DNase I contains four ion-binding pockets. Two of them strongly bind Ca²+ while the other two sites coordinate Mg²+. These theoretical results are strongly supported by revisiting crystallographic structures that contain bpDNase I. One Ca²+ stabilizes the functional DNase I structure. The presence of Mg²+ in close vicinity to the catalytic pocket of bpDNase I reinforces the idea of a cation-assisted hydrolytic mechanism. Importantly, Poisson-Boltzmann-type electrostatic potential calculations demonstrate that the divalent cations collectively control the electrostatic fit between bpDNase I and DNA. These results improve our understanding of the essential role of cations in the biological function of bpDNase I. The high degree of conservation of the amino acids involved in the identified cation-binding sites across DNase I and DNase I-like proteins from various species suggests that our findings generally apply to all DNase I-DNA interactions.
ISSN: 1553-734X

hal-00645165
https://hal.archives-ouvertes.fr/hal-00645165
https://hal.archives-ouvertes.fr/hal-00645165/document
https://hal.archives-ouvertes.fr/hal-00645165/file/journal.pcbi.1001000.pdf
DOI : 10.1371/journal.pcbi.1001000

Éditeur(s) : HAL CCSD Microbiology Society
Résumé : International audience
An actinobacterial strain, designated ViU22(T), was isolated from a natural uranium-rich soil and was studied using a polyphasic approach. Cells formed orange-pigmented colonies, were rod-shaped, Gram-positive (non-staining method), non-motile and non-spore-forming. This organism grew in 0-4.5 % (w/v) NaCl and at 15-37 °C, with optimal growth occurring in 0.5 % (w/v) NaCl and at 30 °C. Comparative 16S rRNA gene sequence analysis revealed that the strain ViU22(T) belonged to the genus Microbacterium. It exhibited highest 16S rRNA gene sequence similarity with the type strains of Microbacterium testaceum (98.14 %) and Microbacterium binotii (98.02 %). The DNA-DNA relatedness of strains ViU22(T) with the most closely related type strains Microbacterium testaceum and Microbacterium binotii DSM 19164(T) was 20.10 % (± 0.70) and 28.05 % (± 0.35), respectively. Strain ViU22(T) possessed a type B2β peptidoglycan with partial substitution of glutamic acid by 3-hydroxy glutamic acid. The major menaquinones were MK-11 and MK-12. Major polar lipids detected in the strain ViU22(T) were diphosphatidylglycerol, phosphatidylglycerol, an unknown phospholipid and unknown glycolipids. The predominant fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0, a pattern reported for other Microbacterium species. The major cell-wall sugars were galactose, xylose and mannose and the DNA G+C content was 71 mol%. Together, the DNA-DNA hybridization results and the differentiating phenotypic characteristics, showed that strain ViU22(T) should be classified as the type strain of a novel species within the genus Microbacterium, for which the name Microbacterium lemovicicum sp. nov. is proposed. The type strain is ViU22(T) ( = ATCC BAA-2396(T) = CCUG 62198(T) = DSM 25044(T)).
ISSN: 1466-5026

hal-01561095
https://hal-amu.archives-ouvertes.fr/hal-01561095
PUBMED : 23264499
DOI : 10.1099/ijs.0.048454-0

Éditeur(s) : HAL CCSD
Résumé : National audience
Aspirin (acetylsalicylic acid) has been used ever since the Antiquity for its painkilling and anti-inflammatory effects. Its antiplatelet properties have then extended its indications to the field of coronaropathy and vascular cerebral disease, and finally to vascular placental disease. Aspirin has been widely prescribed since the 1980's to prevent pre-eclampsia, intra-uterine growth retardation and fetal death of vascular origin. It has also been proposed to prevent unexplained recurrent miscarriages. Its use during pregnancy is considered as safe, provided the daily doses do not exceed 100mg. Aspirin has been proven efficient to prevent pre-eclampsia and fetal growth restriction in high-risk patients. The benefits of prescribing aspirin have been demonstrated neither for vascular placental disease prevention in low risk patients, nor in cases of unexplained recurrent miscarriages.
La Revue De Medecine Interne

hal-01659441
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01659441
DOI : 10.1016/j.revmed.2017.10.419
PUBMED : 29129461

Éditeur(s) : HAL CCSD
Résumé : International audience
In this work, an alkaloids extract from Annona squamosa plant have been studied as possible corrosion inhibitor for C38 steel in molar hydrochloric acid (1 M HCl). Potentiodynamic polarization and AC impedance methods have been used. The corrosion inhibition efficiency increases on increasing plant extract concentration. Polarisation studies showed that Annona squamosa extract was mixed-type inhibitor in 1 M HCl. The inhibition efficiency of Annona squamosa extract was temperaturedependent and its addition led to an increase of the activation corrosion energy revealing a physical adsorption between the extract and the metal surface. The adsorption of the Annona squamosa extractfollowed Langmuir’s adsorption isotherm. The inhibitive effect of Annona squamosa is ascribed to the presence of organic compounds in the extract. The examined extract is considered as non-cytotoxic substance.
International journal of electrochemical science

hal-01094042
https://hal-agroparistech.archives-ouvertes.fr/hal-01094042

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Although TRAIL (tumor necrosis factor (TNF)-related apoptosis inducing ligand) is a well-known apoptosis inducer, we have previously demonstrated that acidic extracellular pH (pHe) switches TRAIL-induced apoptosis to regulated necrosis (or necroptosis) in human HT29 colon and HepG2 liver cancer cells. Here, we investigated the role of RIPK1 (receptor interacting protein kinase 1), RIPK3 and PARP-1 (poly (ADP-ribose) polymerase-1) in TRAIL-induced necroptosis in vitro and in concanavalin A (Con A)-induced murine hepatitis. Pretreatment of HT29 or HepG2 with pharmacological inhibitors of RIPK1 or PARP-1 (Nec-1 or PJ-34, respectively), or transient transfection with siRNAs against RIPK1 or RIPK3, inhibited both TRAIL-induced necroptosis and PARP-1-dependent intracellular ATP depletion demonstrating that RIPK1 and RIPK3 were involved upstream of PARP-1 activation and ATP depletion. In the mouse model of Con A-induced hepatitis, where death of mouse hepatocytes is dependent on TRAIL and NKT (Natural Killer T) cells, PARP-1 activity was positively correlated with liver injury and hepatitis was prevented both by Nec-1 or PJ-34. These data provide new insights into TRAIL-induced necroptosis with PARP-1 being active effector downstream of RIPK1/RIPK3 initiators and suggest that pharmacological inhibitors of RIPKs and PARP-1 could be new treatment options for immune-mediated hepatitis.
ISSN: 1350-9047

inserm-00871432
http://www.hal.inserm.fr/inserm-00871432
DOI : 10.1038/cdd.2012.90
PUBMED : 22814620

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Well-dispersed iron oxide nanoparticles supported onto graphene oxide sheets (i.e. GO-Fe3O4 nanocomposite) were synthesised and used as heterogeneous Fenton-like catalyst for the degradation of Acid Orange 7 dye (AO7). The reaction was systematically investigated under various experimental conditions such as nanocomposite dosage, pH, temperature, oxidant and dye concentrations. Best results showed a fast 80% degradation in ∼20 min, whilst ∼98% of AO7 was successfully removed after 180 min of reaction time. The degradation kinetics of AO7 was most influenced by pH and temperature, and can be described by a pseudo-first-order reaction following the Langmuir-Hinshelwood mechanism. Analysis of the spent nanocomposite suggested that the phase of iron oxide nanoparticles remained unchanged whilst minor pore volume losses occurred via carbon deposition and/or re-stacking of GO sheets. © 2014 Elsevier Ltd.
ISSN: 2213-3437

hal-01683206
https://hal.univ-antilles.fr/hal-01683206
DOI : 10.1016/j.jece.2014.08.001

Éditeur(s) : HAL CCSD
Résumé : International audience
Paracetamol and NSAIDs, in particular acetylsalicylic acid (aspirin) and ibuprofen, are among the most used and environmentally released pharmaceutical drugs. The differences in international trends in the sale and consumption of mild analgesics reflect differences in marketing, governmental policies, habits, accessibility, disease patterns and the age distribution of each population. Biomonitoring indicates ubiquitous and high human exposure to paracetamol and to salicylic acid, which is the main metabolite of acetylsalicylic acid. Furthermore, evidence suggests that analgesics can have endocrine disruptive properties capable of altering animal and human reproductive function from fetal life to adulthood in both sexes. Medical and public awareness about these health concerns should be increased, particularly among pregnant women.
Nature Reviews Endocrinology

hal-01359566
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01359566
DOI : 10.1038/nrendo.2016.55
PUBMED : 27150289

Éditeur(s) : HAL CCSD
Résumé : International audience
The effect of alkaloids extracted from Isertia coccinea plant (AEIC) on the corrosion of C38 steel in 1 M hydrochloric acid was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Potentiodynamic polarization curves indicated that the extract behave as mixed-type inhibitor. The experimental data obtained from EIS method show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The inhibition efficiencies of the extract calculated by three methods show the same tendency. Inhibition was found to increase with increasing concentration of the plant extract. The results obtained show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of C38 steel in hydrochloric acid solution. The apparent activation energy of the process taking place in inhibitor presence was determined on the ground of four temperature values in the range from 25 °C to 55 °C using the data obtained by two independent methods. Theoretical fitting of different isotherms, Langmuir, Temkin and Frunkin, were tested to clarify the nature of adsorption.
International journal of electrochemical science

hal-01097030
https://hal-agroparistech.archives-ouvertes.fr/hal-01097030

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The mycotoxin alternariol (AOH), a frequent contaminant in fruit and grain, is known to induce cellular stress responses such as reactive oxygen production, DNA damage and cell cycle arrest. Cellular stress is often connected to autophagy, and we employed the RAW264.7 macrophage model to test the hypothesis that AOH induces autophagy. Indeed, AOH treatment led to a massive increase in acidic vacuoles often observed upon autophagy induction. Moreover, expression of the autophagy marker LC3 was markedly increased and there was a strong accumulation of LC3-positive puncta. Increased autophagic activity was verified biochemically by measuring the degradation rate of long-lived proteins. Furthermore, AOH induced expression of Sestrin2 and phosphorylation of AMPK as well as reduced phosphorylation of mTOR and S6 kinase, common mediators of signaling pathways involved in autophagy. Transmission electron microscopy analyzes of AOH treated cells not only clearly displayed structures associated with autophagy such as autophagosomes and autolysosomes, but also the appearance of lamellar bodies. Prolonged AOH treatment resulted in changed cell morphology from round into more star-shaped as well as increased β-galactosidase activity. This suggests that the cells eventually entered senescence. In conclusion, our data identify here AOH as an inducer of both autophagy and senescence. These effects are suggested to be to be linked to AOH-induced DSB (via a reported effect on topoisomerase activity), resulting in an activation of p53 and the Sestrin2-AMPK-mTOR-S6K signaling pathway.
ISSN: 0300-483X

hal-01117627
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01117627/file/Autophagy%20and%20senescence_accepted.pdf
PUBMED : 25456271

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
: Until recently, synonymous mutations (which do not change amino acids) have been much neglected. Some evidence suggests that this kind of mutations could affect mRNA secondary structure or stability, translation kinetics and protein structure. To explore deeper the role of synonymous mutations, we studied their consequence on the functional activity of the estrogen receptor alpha (ERα). The ERα is a ligand-inducible transcription factor that orchestrates pleiotropic cellular effects, at both genomic and non-genomic levels in response to estrogens. In this work we analyzed in transient transfection experiments, the activity of ERα carrying the synonymous mutation Ala87, a polymorphism involving about 5-10% of the population. In comparison to the wild type receptor, our results show that ERαA87 mutation reduces the transactivation efficiency of ERα on an ERE reporter gene while its expression level remains similar. This mutation enhances 4-OHT-induced transactivation of ERα on an AP1 reporter gene. Finally, the mutation affects the subcellular localization of ERα in a cell type specific manner. It enhances the cytoplasmic location of ERα without significant changes in non-genomic effects of E2. The functional alteration of the ERαA87 determined in this work highlights the relevance of synonymous mutations for biomedical and pharmacological points of view.
Journal of steroid biochemistry and molecular biology

inserm-01015532
http://www.hal.inserm.fr/inserm-01015532
DOI : 10.1016/j.jsbmb.2014.02.016
PUBMED : 24607813

Éditeur(s) : Society for General Microbiology
Résumé : A novel piezotolerant, mesophilic, facultatively anaerobic, organotrophic, polarly flagellated bacterium (strain LT13a(T)) was isolated from a deep sediment layer in the Nankai Trough (Leg 190, Ocean Drilling Program) off the coast of Japan. This organism used a wide range of organic substrates as sole carbon and energy sources: pyruvate, glutamate, succinate, fumarate, lactate, citrate, peptone and tryptone. Oxygen, nitrate, fumarate, ferric iron and cystine were used as electron acceptors. Maximal growth rates were observed at a hydrostatic pressure of 10 MPa. Hydrostatic pressure for growth was in the range 0.1-50 MPa. Predominant cellular fatty acids were 16:1 omega7c, 15: 0 iso, 16: 0 and 13: 0 iso. The G + C content of the DNA was 44.9 mol%. On the basis of 16S rRNA gene sequences, strain LT13a(T) was shown to belong to the gamma-Proteobacteria, being closely related to Shewanella putrefaciens (98%), Shewanella oneidensis (97%) and Shewanella baltica (96 %). Levels of DNA homology between strain LT13a(T) and S. putrefaciens, S. oneidensis and S. baltica were < 20 %, indicating that strain LT13a(T) represents a novel species. Genetic evidence and phenotypic characteristics showed that isolate LT13a(T) constitutes a novel species of the genus Shewanella, Because of the deep origin of the strain, the name Shewanella profunda sp. nov. is proposed, with LT13a(T) (= DSM 15900(T)-JCM 12080(T)) as the type strain.
International journal of systematic and evolutionary microbiology (1466-5026) (Society for General Microbiology), 2004-11 , Vol. 54 , N. 6 , P. 1943-1949

Droits : 2004 International Union of Microbiological Societies
http://archimer.ifremer.fr/doc/2004/publication-590.pdf
DOI:10.1099/ijs.0.03007-0
http://archimer.ifremer.fr/doc/00000/590/

Éditeur(s) : HAL CCSD American Society for Biochemistry and Molecular Biology
Résumé : International audience
2-Amino-9H-pyrido[2,3-b]indole (AαC) is a carcinogenic heterocyclic aromatic amine formed during the combustion of tobacco. AαC undergoes bioactivation to form electrophilic N-oxidized metabolites that react with DNA to form adducts, which can lead to mutations. Many genotoxicants and toxic electrophiles react with human serum albumin (albumin); however, the chemistry of reactivity of AαC with proteins has not been studied. The genotoxic metabolites, 2-hydroxyamino-9H-pyrido[2,3-b]indole (HONH-AαC), 2-nitroso-9H-pyrido[2,3-b]indole (NO-AαC), N-acetyloxy-2-amino-9H-pyrido[2,3-b]indole (N-acetoxy-AαC), and their [(13)C6]AαC-labeled homologues were reacted with albumin. Sites of adduction of AαC to albumin were identified by data-dependent scanning and targeted bottom-up proteomics approaches employing ion trap and Orbitrap MS. AαC-albumin adducts were formed at Cys(34), Tyr(140), and Tyr(150) residues when albumin was reacted with HONH-AαC or NO-AαC. Sulfenamide, sulfinamide, and sulfonamide adduct formation occurred at Cys(34) (AαC-Cys(34)). N-Acetoxy-AαC also formed an adduct at Tyr(332). Albumin-AαC adducts were characterized in human plasma treated with N-oxidized metabolites of AαC and human hepatocytes exposed to AαC. High levels of N-(deoxyguanosin-8-yl)-AαC (dG-C8-AαC) DNA adducts were formed in hepatocytes. The Cys(34) was the sole amino acid of albumin to form adducts with AαC. Albumin also served as an antioxidant and scavenged reactive oxygen species generated by metabolites of AαC in hepatocytes; there was a strong decrease in reduced Cys(34), whereas the levels of Cys(34) sulfinic acid (Cys-SO2H), Cys(34)-sulfonic acid (Cys-SO3H), and Met(329) sulfoxide were greatly increased. Cys(34) adduction products and Cys-SO2H, Cys-SO3H, and Met(329) sulfoxide may be potential biomarkers to assess exposure and oxidative stress associated with AαC and other arylamine toxicants present in tobacco smoke
ISSN: 0021-9258

hal-01169796
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01169796
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01169796/file/Manuscript_KP_JBC_REV_050515_final_TC.pdf
DOI : 10.1074/jbc.M115.646539
PUBMED : 25953894

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : Dihydroceramide ?4-desaturase 1 (DES1) catalyzes the last step of the de novo ceramide biosynthesis, which consists of the introduction of a trans ?4-double bond in the carbon chain of the dihydroceramide. It was previously observed that myristic acid binds DES1 through N-myristoylation. This N-terminal modification significantly increased the activity of the recombinant DES1 in COS-7 cells and targeted part of the enzyme initially present in the endoplasmic reticulum to the mitochondrial outer membrane, leading to an increase in ceramide levels. Since these results were obtained in a recombinant COS-7 cell model with high expression of rat DES1, the purpose of the present study was to investigate if the native DES1 enzyme was really upregulated by its N-myristoylation in cultured rat hepatocytes. We first showed that DES1 was the main dihydroceramide desaturase isoform expressed in rat hepatocytes. In this model, the wild-type myristoylable recombinant form of rat DES1 was found in both the endoplasmic reticulum and the mitochondria whereas the mutated non-myristoylable recombinant form (N-terminal glycine replaced by an alanine) was almost exclusively localized in the endoplasmic reticulum, which evidenced the importance of the myristoylation. Then, we showed that compared to other fatty acids, myristic acid was the only one to increase native DES1 activity, in both total cell lysates and mitochondrial fractions. The myristic acid-associated increase in DES1 activity was not linked to elevated mRNA or protein expression but more likely to its N-terminal myristoylation. Finally, the myristic acid-associated increase in DES1 activity slightly enhanced the number of apoptotic cells.
ISSN: 0024-4201

hal-00808026
https://hal-agrocampus-ouest.archives-ouvertes.fr/hal-00808026
DOI : 10.1007/s11745-011-3638-x