CD8alphaalpha-mediated survival and differentiation of CD8 memory T cell precursors   总被引：1，自引：0，他引：1  

Madakamutil LT  Christen U  Lena CJ  Wang-Zhu Y  Attinger A  Sundarrajan M  Ellmeier W  von Herrath MG  Jensen P  Littman DR  Cheroutre H 《Science (New York, N.Y.)》2004,304(5670):590-593

Memory T cells are long-lived antigen-experienced T cells that are generally accepted to be direct descendants of proliferating primary effector cells. However, the factors that permit selective survival of these T cells are not well established. We show that homodimeric alpha chains of the CD8 molecule (CD8alphaalpha) are transiently induced on a selected subset of CD8alphabeta+ T cells upon antigenic stimulation. These CD8alphaalpha molecules promote the survival and differentiation of activated lymphocytes into memory CD8 T cells. Thus, memory precursors can be identified among primary effector cells and are selected for survival and differentiation by CD8alphaalpha.  相似文献   

Long road to reform in France     

Brézin E  Triller A 《Science (New York, N.Y.)》2008,320(5884):1695

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Single-molecule kinetics of lambda exonuclease reveal base dependence and dynamic disorder     

van Oijen AM  Blainey PC  Crampton DJ  Richardson CC  Ellenberger T  Xie XS 《Science (New York, N.Y.)》2003,301(5637):1235-1238

We used a multiplexed approach based on flow-stretched DNA to monitor the enzymatic digestion of lambda-phage DNA by individual bacteriophage lambda exonuclease molecules. Statistical analyses of multiple single-molecule trajectories observed simultaneously reveal that the catalytic rate is dependent on the local base content of the substrate DNA. By relating single-molecule kinetics to the free energies of hydrogen bonding and base stacking, we establish that the melting of a base from the DNA is the rate-limiting step in the catalytic cycle. The catalytic rate also exhibits large fluctuations independent of the sequence, which we attribute to conformational changes of the enzyme-DNA complex.  相似文献   

Impacts of climate change on Swiss biodiversity: An indicator taxa approach     

Peter B. Pearman  Antoine Guisan  Niklaus E. Zimmermann 《Biological conservation》2011,(2):866-875

We present a new indicator taxa approach to the prediction of climate change effects on biodiversity at the national level in Switzerland. As indicators, we select a set of the most widely distributed species that account for 95% of geographical variation in sampled species richness of birds, butterflies, and vascular plants. Species data come from a national program designed to monitor spatial and temporal trends in species richness. We examine some opportunities and limitations in using these data. We develop ecological niche models for the species as functions of both climate and land cover variables. We project these models to the future using climate predictions that correspond to two IPCC 3rd assessment scenarios for the development of ‘greenhouse’ gas emissions. We find that models that are calibrated with Swiss national monitoring data perform well in 10-fold cross-validation, but can fail to capture the hot-dry end of environmental gradients that constrain some species distributions. Models for indicator species in all three higher taxa predict that climate change will result in turnover in species composition even where there is little net change in predicted species richness. Indicator species from high elevations lose most areas of suitable climate even under the relatively mild B2 scenario. We project some areas to increase in the number of species for which climate conditions are suitable early in the current century, but these areas become less suitable for a majority of species by the end of the century. Selection of indicator species based on rank prevalence results in a set of models that predict observed species richness better than a similar set of species selected based on high rank of model AUC values. An indicator species approach based on selected species that are relatively common may facilitate the use of national monitoring data for predicting climate change effects on the distribution of biodiversity.  相似文献   

Earthworm indicators as tools for soil monitoring,characterization and risk assessment. An example from the national Bioindicator programme (France)     

Guénola Pérès  Franck Vandenbulcke  Muriel Guernion  Mickaël Hedde  Thierry Beguiristain  Francis Douay  Sabine Houot  Denis Piron  Antoine Richard  Antonio Bispo  Cécile Grand  Laurence Galsomies  Daniel Cluzeau 《Pedobiologia》2011

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Biocontrol potential of native Trichoderma isolates against root-knot nematodes in West African vegetable production systems     

Antoine Affokpon  Danny L. Coyne  Rufin Dossou Agbèdè  Jozef Coosemans 《Soil biology & biochemistry》2011,43(3):600-608

Seventeen isolates of the free-living soil fungus Trichoderma spp., collected from Meloidogyne spp. infested vegetable fields and infected roots in Benin, were screened for their rhizosphere competence and antagonistic potential against root-knot nematodes, Meloidogyne incognita, in greenhouse pot experiments on tomato. The five isolates expressing greatest reproductive ability and nematode suppression in pots were further assessed in a typical double-cropping system of tomato and carrot in the field in Benin. All seventeen isolates were re-isolated from both soil and roots at eight weeks after application, with no apparent crop growth penalty. In pots, a number of isolates provided significant nematode control compared with untreated controls. Field assessment demonstrated significant inhibition of nematode reproduction, suppression of root galling and an increase of tomato yield compared with the non-fungal control treatments. Trichoderma asperellum T-16 suppressed second stage juvenile (J₂) densities in roots by up to 80%; Trichoderma brevicompactum T-3 suppressed egg production by as much as 86%. Tomato yields were improved by over 30% following the application of these biocontrol agents, especially T. asperellum T-16. Although no significant effects were observed on carrot galling and yield, soil J₂ densities were suppressed in treated plots, by as much as 94% (T. asperellum T-12), compared with the non-fungal controls. This study provides the first information on the potential of West-African Trichoderma spp. isolates for use against root-knot nematodes in vegetable production systems. The results are highly encouraging, demonstrating their strong potential as an alternative and complementary crop protection component.  相似文献   

Lamellodiscus (Monogenea: Diplectanidae) parasites of Dentex macrophthalmus (Teleostei: Sparidae) from the North Atlantic coast of Africa, with a redescription of L. dentexi Aljoshkina, 1984, and description of three new species     

Diamanka A  Neifar L  Pariselle A  Euzet L 《Folia parasitologica》2011,58(1):17-26

Lamellodiscus dentexi Aljoshkina, 1984, a gill parasite of Dentex macrophthalmus (Bloch), is redescribed based on new material from the northwest coast of Africa (Senegal and Morocco). Three new species of Lamellodiscus Johnston et Tiegs, 1922 from D. macrophthalmus are described, Lamellodiscus toguebayei sp. n., L. vicinus sp. n., and L. triacies sp. n., all belonging to the "ignoratus" group. They can be distinguished from all other species of this group by the size and shape of male copulatory organ and sclerotised parts of the haptor. Considering the peculiar morphology of the male copulatory organ (long and thin tube) we propose to put together L. dentexi, L. virgula Euzet et Oliver, 1967 and L. obeliae Oliver, 1973 to form the "elongatus" type within the "elegans" group.  相似文献   

Possible role of plant phenolics in the production of trichothecenes by Fusarium graminearum strains on different fractions of maize kernels     

Bakan B  Bily AC  Melcion D  Cahagnier B  Regnault-Roger C  Philogène BJ  Richard-Molard D 《Journal of agricultural and food chemistry》2003,51(9):2826-2831

Four trichothecene-producing strains of Fusarium graminearum were grown on three maize grain fractions, whole grain, degermed grain, and the germ, to determine the effect of natural substrates on mycotoxin production. Monitoring the ergosterol content after 25 days of incubation indicated that fungal growth on all grain fractions was comparable. Trichothecene (TCT) production was highest on degermed grain, less on whole grain, and very low or nondetectable on the germ; similar results were found with four different strains. It was concluded that inhibitor(s) of TCT biosynthesis were present in maize germ. The presence of phenolic compounds was investigated in the different fractions. The hydroxamate 4-acetylbenzoxazolin-2-one (4-ABOA), a known inhibitor of mycotoxin production, was found in the degermed and whole grain fractions but not in the germ. Therefore, the TCT inhibition observed on the maize germ fraction used in our study is clearly not linked to 4-ABOA. Other soluble phenolic compounds were found at a much higher concentration in the germ than in the two other fractions. The inhibition property of the soluble ester-bound extracts was tested in liquid culture. A possible role for these compounds is discussed.  相似文献   

Management of human health risk in the context of kitchen gardens polluted by lead and cadmium near a lead recycling company     

Stéphane Mombo  Yann Foucault  Frédéric Deola  Irène Gaillard  Sylvaine Goix  Muhammad Shahid  Eva Schreck  Antoine Pierart  Camille Dumat 《Journal of Soils and Sediments》2016,16(4):1214-1224

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Development of Purkinje cells in the ovine brain     

Salouci M  Engelen V  Gyan M  Antoine N  Jacqmot O  Mignon Y  Kirschvink N  Gabriel A 《Anatomia, histologia, embryologia》2012,41(3):227-232

Purkinje cells are involved in many vital functions within the body. Twenty ovine fetuses ranging from 2 to 5 months of gestation, two lambs in the first week after birth and three adult sheep were studied. Sections of the cerebellum were stained with haematoxylin and eosin, cresyl violet and Klüver-Barrera. This study indicates that Purkinje cells began to appear after the 15(th) week of gestation. There were varying degrees of development of Purkinje cells in different zones of the cerebellum. Our findings in sheep fetuses suggest that the maturation of Purkinje cells starts in the caudal regions of the cerebellum and that the process begins in the vermis before it does in the cerebellar hemispheres. The alignment of Purkinje cells was found to be very regular in the caudal regions of the cerebellum. A partial absence of Purkinje cells in the rostral regions of the cerebellum was observed in both sheep fetuses and adult sheep. In the first post-natal week, some ectopic Purkinje cells were found in the white matter of the cerebellum.  相似文献