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51.
Peter R. Bieck Karl-Heinz Antonin Gisbert Farger Erik B. Nilsson Eckhart K. Schmidt Philippe Dostert Margherita Strolin Benedetti Peter C. Waldmeier 《Neurochemical research》1993,18(11):1163-1167
CGP 28 014 is a specific inhibitor of catechol-O-methyltransferase (COMT) in vivo. In humans, the inhibition was assessed by measuring urinary excretion of isoquinolines and with the levodopa test. Following administration of CGP 28 014, urinary excretion of isoquinolines was significantly increased. In rats, CGP 28 014 reduced plasma and striatal concentrations of 3-O-methyldopa (30MD) in a dose-dependent manner. Acute and subchronic administration of CGP 28 014 alone or in combination with the peripherally acting decarboxylase inhibitor benserazide decreased plasma 30MD as an index of COMT inhibition by about 50%. There seems to be a close relationship between the time-course of plasma concentrations of CGP 28 014 and the extent of COMT inhibition assessed by the 30MD/DOPA ratio in plasma. 相似文献
52.
Valérie Michel Gérard Fonty Liliane Millet Frédérique Bonnemoy Philippe Gouet 《FEMS microbiology letters》1993,110(1):5-9
Abstract To better define the antigenic structure of the outer cell membranes of Legionellae, a panel of 6 monoclonal antibodies was raised against partially purified outer membranes of Legionella pneumophila serogroup 1, Corby strain. This study describes the purification and characterization of one of these monoclonal antibodies reacting with a 135-kDa protein, which was shown to be common to all 14 serogroups of Legionella pneumophila . It shows no cross-reactivity with 20 other Legionella species, or 9 other Gram-negative species tested by SDS-PAGE and Western blotting procedures. The epitope would appear to be predominantly surface exposed and, from preliminary detergent extraction studies, not peptidoglycan-associated. 相似文献
53.
Lucie Mahaut Philippe Choler Pierre Denelle Eric Garnier Wilfried Thuiller Jens Kattge Servane Lemauviel-Lavenant Sandra Lavorel François Munoz Delphine Renard Josep M. Serra-Diaz Nicolas Viovy Cyrille Violle 《Global Ecology and Biogeography》2023,32(4):561-572
Aim
It is crucial to monitor how the productivity of grasslands varies with its temporal stability for management of these ecosystems. However, identifying the direction of the productivity–stability relationship remains challenging because ecological stability has multiple components that can display neutral, positive or negative covariations. Furthermore, evidence suggests that the direction of the productivity–stability relationship depends on the biotic interactions and abiotic conditions that underlie ecosystem productivity and stability. We decipher the relationships between grassland productivity and two components of its stability in four habitat types with contrasting environments and flora.Location
France.Time period
2000–2020.Major taxa
Grassland plant species.Methods
We used c. 20,000 vegetation plots spread across French permanent grasslands and remotely sensed vegetation indices to quantify grassland productivity and temporal stability. We decomposed stability into constancy (i.e., temporal invariability) and resistance (i.e., maximum deviation from average) and deciphered the direct and indirect effects of abiotic (namely growing season length and nitrogen input) and biotic (namely plant taxonomic diversity, trait diversity and community-weighted mean traits) factors on productivity–stability relationships using structural equation models.Results
We found a positive relationship between productivity and constancy and a negative relationship between productivity and resistance in all habitats. Abiotic factors had stronger effects on productivity and stability compared with biotic factors. A longer growing season enhanced grassland productivity and constancy. Nitrogen input had positive and negative effects on grassland productivity and resistance, respectively. Trait values affected the constancy and resistance of grassland more than taxonomic and trait diversity, with effects varying from one habitat to another. Productivity was not related to any biotic factor.Main conclusions
Our findings reveal how vital it is to consider both the multiple components of stability and the interaction between environment and biodiversity to gain an understanding of the relationships between productivity and stability in real-world ecosystems, which is a crucial step for sustainable grassland management. 相似文献54.
Machhour Ghazali Michel Philippe Alain Deguercy Pierre Gounon Jean-Marc Gallo Joseph Schrevel 《Biology of the cell / under the auspices of the European Cell Biology Organization》1989,67(2):173-184
In Gregarina blaberae a Mr = 47 000 and a Mr = 260–240 000 doublet polypeptides reacted in immunoblotting: i) with a polyclonal monospecific rabbit antibody to frog muscular actin, a monoclonal anti-actin antibody against chicken gizzard; and ii) with polyclonal and monoclonal antibodies to human erythrocyte β-spectrin, respectively. The Mr = 47 000 actin-like protein is associated with the ghost and a contractille cytoplasmic extract. The presence of an actin-like protein in Gregarina and Lecudina and its cellular distribution in the cortex indicated that the gliding movement might involve an actin-myosin system in contrast to previous studies. Immunofluorescence showed clear differences between the anterior part of Gregarina and Lecudina which illustrated the high cell polarity of these protozoa. The Mr = 260–240 000 doublet was detected in SDS-PAGE from G. blaberae trophozoite ghosts but not in the cytoplasmic extracts or in extracts from sexual stages, indicating that the presence of these spectrin-like proteins is stage-dependent. Visualization of the Mr = 260–240 000 by immunofluorescence showed clear species differences, with rings arranged perpendicular to the longitudinal narrow folds of G. blaberae, with longitudinal lines underlying the folds of L. pellucida and with lines separating the large folds of Selenidium pendula. The cellular distribution is consistent with a stabilizer function of the spectrin-like proteins in the scaffolding of the cortex of gregarines according to the high diversity of the cell-shape and the cell motility systems in gregarines. The presence of spectrin-like proteins in protozoa and particularly in parasites from primitive arthropods indicated that ancestral spectrin genes could the Mr = 260–240 000 form. 相似文献
55.
Jean Quancard Philippe Karoyan Sandrine Sagan Odile Convert Solange Lavielle Gérard Chassaing Olivier Lequin 《European journal of biochemistry》2003,270(13):2869-2878
Residue Leu10 of substance P (SP) is critical for NK-1 receptor recognition and agonist activity. In order to probe the bioactive conformation of this residue, cis- and trans-3-substituted prolinoleucines were introduced in position 10 of SP. The substituted SP analogues were tested for their affinity to human NK-1 receptor specific binding sites (NK-1M and NK-1m) and their potency to stimulate adenylate cyclase and phospholipase C in CHO cells transfected with the human NK-1 receptor. [trans-3-prolinoleucine10]SP retained affinity and potency similar to SP whereas [cis-3-prolinoleucine10]SP shows dramatic loss of affinity and potency. To analyze the structural implications of these biological results, the conformational preferences of the SP analogues were analyzed by NMR spectroscopy and minimum-energy conformers of Ac-cis-3-prolinoleucine-NHMe, Ac-trans-3-prolinoleucine-NHMe and model dipeptides were generated by molecular mechanics calculations. From NMR and modeling studies it can be proposed that residue Leu10 of SP adopts a gauche(+) conformation around the chi1 angle and a trans conformation around the chi2 angle in the bioactive conformation. Together with previously published results, our data indicate that the C-terminal SP tripeptide should preferentially adopt an extended conformation or a PPII helical structure when bound to the receptor. 相似文献
56.
57.
Identification and cellular localization of the actin-binding protein ABP-120 from Entamoeba histolytica 总被引:1,自引:0,他引:1
Several actin-binding proteins participate in the morphological changes that occur during amoeboid movement. The gene encoding one of these proteins, the gelation factor ABP-120, was identified and characterized from trophozoites of Entamoeba histolytica . The sequence contains 2574 nucleotides, with an open reading frame of 858 amino acids, giving a protein of 93 kDa belonging to the spectrin family. The N-terminal domain of ABP-120 from E. histolytica revealed a consensus site for actin binding homologous to the actin-binding sites of ABP-120 of Dictyostelium discoideum , α-actinin and spectrin. Analysis of the central domain revealed the presence of four repeats of a 73-amino-acid motif constituting 31% of the protein. In addition, a stretch of 105 amino acids was highly divergent when compared with the C-terminal domain of D. discoideum ABP-120. This sequence showed short motifs that are homologous to microtubule-binding domains. We found that ABP-120 from E. histolytica binds to F-actin. In addition, upon motility of the parasite, this protein localized in the pseudopod and the uroid region, implying a role for ABP-120 in movement and capping of surface receptors in E. histolytica . 相似文献
58.
Begging, food provisioning, and nestling competition in great tit broods infested with ectoparasites 总被引:9,自引:5,他引:4
Ectoparasites are a ubiquitous environmental component of breedingbirds, and it has repeatedly been shown that hematoph-agousectoparasites such as fleas and mites reduce the quality andnumber of offspring of bird hosts, thereby lowering the valueof a current brood. Selection acting on the hosts will favorphysiological and behavioral responses that will reduce theparasites' impact. However, the results of the few bird studiesthat addressed the question of whether parasitism leads to ahigher rate of food provisioning are equivocal, and the beggingresponse to infestation has rarely been quantified. A changein begging activity and parental rate of food provisioning couldbe predicted in either direction: parents could reduce theirinvestment in the brood in order to invest more in future broods,or they could increase their investment in order to compensatefor the parasites' effect on the current brood. Since the nestlingsare weakened by the ectoparasites they may beg less, but onthe other hand they may beg more in order to obtain more food.In this study we show experimentally that (1) hen fleas (Ceratophyllusgallinae) reduce the body mass and size of great tit (Parusmajor) nestlings, (2) nestlings of parasitized broods more thandouble their begging rate, (3) the male parents increase thefrequency of feeding trips by over 50%, (4) the females do notadjust feeding rate to the lowered nutritional state of nestlings,and (5) food competition among siblings of parasitized broodsis increased. Ultimately the difference in the parental feedingresponse may be understood as the result of a sex-related differencein the trade-off of i0vesting in current versus future broods. 相似文献
59.
Rita Zilhão Joël Caillet Philippe Régnier Cecilia M. Arraiano 《Molecular & general genetics : MGG》1995,248(2):242-246
Ribonuclease II (encoded byrnb) is one of the two main exonucleases involved in mRNA degradation inEscherichia coli. We report the precise physical mapping ofrnb to 29 min on the chromosomal map in the vicinity ofpyrF, and clarify the genetic and physical maps of thisE. coli chromosomal region. The results were confirmed by the construction of a strain partially deleted forrnb. 相似文献
60.
Sabine Castano Bernard Desbat Isabelle Cornut Philippe Méléard Jean Dufourcq 《Letters in Peptide Science》1997,4(4-6):195-200
De novo designed extremely simplified amphipathic basicLeuiLysj (i = 2j) peptides of 8, 9 and 15residues were synthesized to clarify the mechanism of action of naturalcytotoxic and hemolytic small proteins or peptides. They proved to havestrong hemolytic activity towards human erythrocytes which increases withpeptide length. These peptides are highly surface active and form stablepeptidic films at the air/water interface. The sensitive and efficient FTIRmodulated polarization technique (PMIRRAS) allows one to obtain in situstructural and orientational information about the peptides at theinterface. A transition of secondary structure is observed: the shorterpeptides (8 and 9 residues) adopt -sheet structures while the longerone (15 residues) is folded into an -helix. In both cases, the peptideslie with the axis parallel to the interface. Their insertion into adimyristoylphosphatidylcholine monolayer can be followed from the increasein the surface and/or pressure of the films. In the mixed films, thepeptides adopt the same structure and orientation as observed at theair/water interface. Therefore, among the same series of peptides, atransition from -sheet to -helix occurs when the length increases(roughly >10 aa), but despite this drastic change both types ofstructures result in strongly hemolytic peptides. 相似文献