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91.
Charles Coudray Sylvie Pucheu François Boucher Josiane Arnaud Joël de Leiris Alain Favier 《Biological trace element research》1994,41(1-2):69-75
The hypothesis that oxygen-derived free radicals play an important role in myocardial ischemic and reperfusion injury has received a lot of support. In the presence of catalytic amounts of transition metals such as iron, superoxide anions, and hydrogen peroxide can be transformed into a highly reactive hydroxyl radical °OH (Haber-Weiss reaction). In view of this, we have undertaken this study to investigate whether iron is involved in the reperfusion syndrome and therefore could aggravate free radicals injury. Coronary effluent iron concentrations and cardiac cytosolic iron levels were evaluated in rat hearts subjected to an ischemia/reperfusion sequences. In the case of total ischemia, iron concentration in coronary effluents peaked immediately in the first sample collected upon reperfusion. However, in the case of partial ischemia, iron concentration in coronary effluents peaked rather exclusively during ischemia period. Cardiac cytosolic iron level augmented significantly after 30 min of total ischemia and non significantly in the other ischemia protocols compared to perfused control hearts. It also appears that the iron released is not protein-bound, and could therefore have a marked catalytic activity. The results of the present study suggest that in the oxygen paradox, iron plays an important role in inducing alterations during reoxygenation. 相似文献
92.
Elisabeth Steichen-Gersdorf Holly H. Gallion Deborah Ford Catherine Girodet Douglas F. Easton Richard A. DiCioccio Gareth Evans Margaret A. Ponder Carole Pye Sylvie Mazoyer Tetsuro Noguchi Fabienne Karengueven Hagay Sobol A. Hardouin Yves-Jean Bignon M. Steven Piver Simon A. Smith Bruce A. J. Ponder 《American journal of human genetics》1994,55(5):870-875
In a study of nine families with “site-specific” ovarian cancer (criterion: three or more cases of epithelial ovarian cancer and no cases of breast cancer diagnosed at age <50 years) we have obtained evidence of linkage to the breast-ovarian cancer susceptibility gene, BRCA1 on 17q12-21. If the risk of cancer in these families is assumed to be restricted to the ovary, the best estimate of the proportion of families linked to BRCA1 is .78 (95% confidence interval .32–1.0). If predisposition to both breast and ovarian cancer is assumed, the proportion linked is 1.0 (95% confidence interval .46–1.0). The linkage of familial site-specific ovarian cancer to BRCA1 indicates the possibility of predictive testing in such families; however, this is only appropriate in families where the evidence for linkage to BRCA1 is conclusive. 相似文献
93.
Candida albicans infection leads to barrier breakdown and a MAPK/NF‐κB mediated stress response in the intestinal epithelial cell line C2BBe1 下载免费PDF全文
94.
The range of genetic variation of spontaneous chromosome doubling frequency of maize haploid plantlets derived from in vitro
anther culture was evaluated. When regeneration is obtained by direct embryo-genesis, bypassing the callus phase, it appears
that the frequency of spontaneous doubling may exceed 40 of the regenerated plantlets. This high frequency may be one consequence
of the use of doubled haploid lines derived from anther culture and spontaneous chromosome doubling. We also report an increase,
by more than 50, of the productivity of diploid fertile regenerated plantlets produced by colchicine supplemented medium during
the cold shock pretreatment of the microspores inside the anthers. Optimization of the treatments and the anther culture procedure
are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
95.
Olaia Liñero Jean-Yves Cornu Frederic Candaudap Oleg S. Pokrovsky Sylvie Bussière Cécile Coriou Théophile Humann-Guilleminot Thierry Robert Stéphane Thunot Alberto de Diego Christophe Nguyen 《Plant and Soil》2016,408(1-2):163-181
Aims
This work concentrated on understanding the allocation of Cd recently taken up between the organs of sunflower at early and middle reproductive growth stages. The roles of transpiration and allometry were investigated.Methods
Sunflowers were grown hydroponically in greenhouse, being exposed to low concentrations of Cd (pCd2+ = 11.03). At flower bud and grain filling stages, plants were exposed for three days to 111Cd and at the same time, subjected or not to fans to increase the transpiration. The partitioning of 111Cd between plant organs measured by high resolution ICP-MS was then modelled.Results
Although the use of fans increased the plant water uptake and transpiration by about 20%, there were no significant effects on the partitioning of recent Cd. Most of the recent Cd was recovered in roots (60%) and only 2.8% were found in seeds (0.8% for the husk and 2.0% for the almonds). The sequestration of recent Cd in a plant organ was successfully explained by its biomass and except for leaves, by the biomass of other organs acting as competitive sinks.Conclusions
This work proposes a modelling approach for the partitioning of the labelled Cd between plant organs in sunflower.96.
Marcel M. Lambrechts Jacques Blondel Sylvie Hurtrez-Bousses Marie Maistre Philippe Perret 《Evolutionary ecology》1997,11(5):599-612
Few studies of natural populations have investigated how phenotypic variation across populations relates to key factors in the environment and landscape structure. In the blue tits of southern France, inter-population differences in reproductive life-history traits (e.g. laying date and clutch size) are small, whatever the timing of maximum caterpillar availability, a key factor for offspring survival in tits. These small differences are attributed to gene flow between local populations occupying different habitat types. In contrast, in blue tits on the island of Corsica, we noted large differences in reproductive life-history traits between two populations, where each population is synchronized with the peak-date of caterpillar abundance. These occur over a short geographical distance (25km). Considering our study within a framework of long-term population studies in tits, our results support the hypothesis that different blue tit populations on Corsica show adaptive differences in life-history traits, and suggest that landscape structure at a small spatial scale can have profound effects on adaptive between-population differentiation in life-history traits that are closely linked with fitness. 相似文献
97.
High blowfly parasitic loads affect breeding success in a Mediterranean population of blue tits 总被引:4,自引:0,他引:4
Sylvie Hurtrez-Boussès Philippe Perret François Renaud Jacques Blondel 《Oecologia》1997,112(4):514-517
The detrimental effects of ectoparasites on the breeding success of birds have been especially well demonstrated in the case
of ectoparasites that affect both chicks and their parents. Since blowfly larvae of the genus Protocalliphora attack only nestling birds, they represent a good model for testing the consequences of parasitism on nestlings. A Corsican
population of blue tit suffers extremely high rates of infestation by blowflies, which are suspected to negatively affect
young birds. Comparing experimentally deparasitized (treated) and naturally infested (control) broods, we showed that the
attack by Protocalliphora causes anaemia and an important disturbance to the chicks. Therefore, we expected that these effects would have a negative
impact on body condition and survival in the infested broods. Although we did not find any effect of treatment on fledging
success, our predictions were confirmed by lower growth rate, body mass at fledging and tarsus length at fledging in the control
compared with the treated group. This suggests that in this population, blowflies decrease the probability of recruitment
of young blue tits.
Received: 6 May 1997 / Accepted: 14 July 1997 相似文献
98.
Isabelle Sgalas Yann Prigent Daniel Davoust Bernard Bodo Sylvie Rebuffat 《Biopolymers》1999,50(1):71-85
The three‐dimensional solution structure of harzianin HC IX, a peptaibol antibiotic isolated from the fungus Trichoderma harzianum, was determined using CD, homonuclear, and heteronuclear two‐dimensional nmr spectroscopy combined with molecular modeling. This 14‐residue peptide, Ac Aib1 Asn2 Leu3 Aib4 Pro5 Ala6 Ile7 Aib8 Pro9 Iva10 Leu11 Aib12 Pro13 Leuol14 (Aib, α‐aminoisobutyric acid; Iva, isovaline; Leuol, leucinol), is a main representative of a short‐sequence peptaibol class characterized by an acetylated N‐terminus, a C‐terminal amino alcohol, and the presence of three Aib‐L ‐Pro motifs at positions 4–5, 8–9, and 12–13, separated by two dipeptide units. In spite of a lower number of residues, compared to the 18/20‐residue peptaibols such as alamethicin, harzianin HC IX exhibits remarkable membrane‐perturbing properties. It interacts with phospholipid bilayers, increasing their permeability and forming voltage‐gated ion channels through a mechanism slightly differing from that proposed for alamethicin. Sequence‐specific 1H‐ and 13C‐nmr assignments and conformational nmr parameters (3JNHCαH coupling constants, quantitative nuclear Overhauser enhancement data, temperature coefficients of amide and carbonyl groups, NH–ND exchange rates) were obtained in methanol solution. Sixty structures were calculated based on 98 interproton distance restraints and 6 Φ dihedral angle restraints, using high temperature restrained molecular dynamics and energy minimization. Thirty‐seven out of the sixty generated structures were consistent with the nmr data and were convergent. The peptide backbone consists in a ribbon of overlapping β‐turns twisted into a continuous spiral from Asn2 to Leuol14 and forming a 26 Å long helix‐like structure. This structure is slightly amphipathic, with the three Aib–Pro motifs aligned on the less hydrophobic face of the spiral where the Asn2 side chain is also present, while the more hydrophobic bulky side chains of leucines, isoleucine, isovaline, and leucinol are located on the concave side. The repetitive (Xaa–Yaa–Aib–Pro) tetrapeptide subunit, making up the peptide sequence, is characterized by four sets of (Φ,Ψ) torsional angles, with the following mean values: Φi = −90°, Ψi = −27°; Φi+1 = −98°, Ψi+1 = −17°; Φi+2 = −49°, Ψi+2 = −50°; Φi+3 = −78°, Ψi+3 = +3°. We term this particular structure, specifically occurring in the case of (Xaa–Yaa–Aib–Pro)n sequences, the (Xaa–Yaa–Aib–Pro)‐β‐bend ribbon spiral. It is stabilized by 4 → 1 intramolecular hydrogen bonds and differs from both the canonical 310‐helix made of a succession of type III β‐turns and from the β‐bend ribbon spiral that has been described in the case of (Aib–Pro)n peptide segments. © 1999 John Wiley & Sons, Inc. Biopoly 50: 71–85, 1999 相似文献
99.
Bradesi S Golovatscka V Ennes HS McRoberts JA Karagiannides I Karagiannidis I Bakirtzi K Pothoulakis C Mayer EA 《American journal of physiology. Gastrointestinal and liver physiology》2011,301(3):G580-G589
Glutamate (Glu) is the primary excitatory neurotransmitter in the central nervous system and plays a critical role in the neuroplasticity of nociceptive networks. We aimed to examine the role of spinal astroglia in the modulation of glutamatergic neurotransmission in a model of chronic psychological stress-induced visceral hyperalgesia in male Wistar rats. We assessed the effect of chronic stress on different glial Glu control mechanisms in the spinal cord including N-methyl-d-aspartate receptors (NMDARs), glial Glu transporters (GLT1 and GLAST), the Glu conversion enzyme glutamine synthetase (GS), and glial fibrillary acidic protein (GFAP). We also tested the effect of pharmacological inhibition of NMDAR activation, of extracellular Glu reuptake, and of astrocyte function on visceral nociceptive response in naive and stressed rats. We observed stress-induced decreased expression of spinal GLT1, GFAP, and GS, whereas GLAST expression was upregulated. Although visceral hyperalgesia was blocked by pharmacological inhibition of spinal NMDARs, we observed no stress effects on NMDAR subunit expression or phosphorylation. The glial modulating agent propentofylline blocked stress-induced visceral hyperalgesia, and blockade of GLT1 function in control rats resulted in enhanced visceral nociceptive response. These findings provide evidence for stress-induced modulation of glia-controlled spinal Glu-ergic neurotransmission and its involvement in chronic stress-induced visceral hyperalgesia. The findings reported in this study demonstrate a unique pattern of stress-induced changes in spinal Glu signaling and metabolism associated with enhanced responses to visceral distension. 相似文献
100.