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991.
Rapid and dissimilar response of ammonia oxidizing archaea and bacteria to nitrogen and water amendment in two temperate forest soils 总被引:2,自引:0,他引:2
Szukics U Hackl E Zechmeister-Boltenstern S Sessitsch A 《Microbiological research》2012,167(2):103-109
Biochemical processes relevant to soil nitrogen (N) cycling are performed by soil microorganisms affiliated with diverse phylogenetic groups. For example, the oxidation of ammonia, representing the first step of nitrification, can be performed by ammonia oxidizing bacteria (AOB) and, as recently reported, also by ammonia oxidizing archaea (AOA). However, the contribution to ammonia oxidation of the phylogenetically separated AOA versus AOB and their respective responsiveness to environmental factors are still poorly understood. The present study aims at comparing the capacity of AOA and AOB to momentarily respond to N input and increased soil moisture in two contrasting forest soils. Soils from the pristine Rothwald forest and the managed Schottenwald forest were amended with either NH(4)(+)-N or NO(3)(-)-N and were incubated at 40% and 70% water-filled pore space (WFPS) for four days. Nitrification rates were measured and AOA and AOB abundance and community composition were determined via quantitative PCR (qPCR) and terminal restriction length fragment polymorphism (T-RFLP) analysis of bacterial and archaeal amoA genes. Our study reports rapid and distinct changes in AOA and AOB abundances in the two forest soils in response to N input and increased soil moisture but no significant effects on net nitrification rates. Functional microbial communities differed significantly in the two soils and responded specifically to the treatments during the short-term incubation. In the Rothwald soil the abundance and community composition of AOA were affected by the water content, whereas AOB communities responded to N amendment. In the Schottenwald soil, by contrast, AOA responded to N addition. These results suggest that AOA and AOB may be selectively influenced by soil and management factors. 相似文献
992.
Sourour Boussaid-Om Ezzine Sonia Métayer-Coustard Anne Collin Nicole Rideau Christine Leterrier Isabelle Bouvarel Iban Seiliez Sophie Tesseraud 《The Journal of nutritional biochemistry》2012,23(11):1467-1473
There is evidence that the E3 ubiquitin ligases muscle ring finger-1 (MuRF1) and atrogin-1, which mediate the ubiquitination of certain proteins and thereby their proteolysis, are regulated by cyclical nutritional treatments varying in lysine content. In order to explore further the regulatory mechanisms involved in metabolic adaptation to dietary changes, we investigated the effects of daily variations in energy [2800 (E?) followed by 3200 kcal/kg (E+)], protein [230 (P+) followed by 150g/kg (P?)] or both [E?P+ followed by E+P?] on muscle protein metabolism in 2-week-old male broiler chickens. Growth performance was similar for all treatments. Expression of atrogin-1 and MuRF1 was changed by alternation of diets varying in protein (higher expression with P? vs. P+) and energy content (higher expression with E? vs. E+). The expression of atrogin-1 was regulated with mixed diets (increase in E+P? vs. E?P+) but not that of MuRF1. Such regulation may involve the mammalian target of rapamycin (mTOR), which was more phosphorylated with P+ than with P?. Eukaryotic initiation factor 4E binding protein, p70S6 kinase and ribosomal protein S6, which are mTOR targets known to control protein synthesis, were highly activated by increased protein content (P+ vs. P?). The mechanisms coordinating the protein synthesis/proteolysis balance remain to be characterized. 相似文献
993.
Cytokines are well recognized for the pleiotropic nature of their signaling and biological activities on many cell types and their role in health and disease. Recent years have seen a steady stream of new cytokine receptor crystal structures including those that are activated by GM-CSF, type I interferon, and a variety of interleukins. Highlights include the observation of a dodecameric signaling complex for the GM-CSF receptor, electron microscopy imaging of an intact gp130/IL-6/IL-6Rα ternary receptor complex bound to its signal transducing Janus kinase and visualization of novel cytokine recognition mechanisms in the interleukin-17 and type I interferon families. This increasing knowledge in cytokine structural biology is driving new opportunities for developing novel therapies to modulate cytokine function in a diverse range of diseases including malignancies and chronic inflammation. 相似文献
994.
Towards deciphering dynamic changes and evolutionary mechanisms involved in the adaptation to low salinities in Ectocarpus (brown algae) 总被引:1,自引:0,他引:1
995.
996.
Sophie Blanc Sabine Wiedemann-Merdinoglu Vincent Dumas Pere Mestre Didier Merdinoglu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2012,125(8):1663-1675
Muscadinia rotundifolia, a species closely related to cultivated grapevine Vitis vinifera, is a major source of resistance to grapevine downy and powdery mildew, two major threats to cultivated traditional cultivars of V. vinifera respectively caused by the oomycete Plasmopara viticola and the ascomycete Erisyphe necator. The aim of the present work was to develop a reference genetic linkage map based on simple sequence repeat (SSR) markers for M. rotundifolia. This map was created using S1 M. rotundifolia cv. Regale progeny, and covers 948?cM on 20 linkage groups, which corresponds to the expected chromosome number for muscadine. The comparison of the genetic maps of V. vinifera and M. rotundifolia revealed a high macrosynteny between the genomes of both species. The S1 progeny was used to assess the general level of resistance of M. rotundifolia to P. viticola and E. necator, by scoring different parameters of pathogen development. A quantitative trait locus (QTL) analysis allowed us to highlight a major QTL on linkage group 14 controlling resistance to powdery mildew, which explained up to 58?% of the total phenotypic variance. This QTL was named ‘Resistance to Erysiphe Necator 5’ (Ren5). A microscopic evaluation E. necator mycelium development on resistant and susceptible genotypes of the S1 progeny showed that Ren5 exerts its action after the formation of the first appressorium, and acts by delaying, and then stopping, mycelium development. 相似文献
997.
Selenium is an essential trace element incorporated into selenoproteins as selenocysteine. Selenocysteine (Sec) lyases (SCLs) and cysteine (Cys) desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys, respectively, and generally accept both substrates. Intriguingly, human SCL (hSCL) is specific for Sec even though the only difference between Sec and Cys is a single chalcogen atom.The crystal structure of hSCL was recently determined and gain-of-function protein variants that also could accept Cys as substrate were identified. To obtain mechanistic insight into the chemical basis for its substrate discrimination, we here report time-resolved spectroscopic studies comparing the reactions of the Sec-specific wild-type hSCL and the gain-of-function D146K/H389T variant, when given Cys as a substrate. The data are interpreted in light of other studies of SCL/CD enzymes and offer mechanistic insight into the function of the wild-type enzyme. Based on these results and previously available data we propose a reaction mechanism whereby the Sec over Cys specificity is achieved using a combination of chemical and physico-mechanical control mechanisms. 相似文献
998.
The mammalian tick-borne flavivirus group (MTBFG) contains viruses associated with important human and animal diseases such as encephalitis and hemorrhagic fever. In contrast to mosquito-borne flaviviruses where recombination events are frequent, the evolutionary dynamic within the MTBFG was believed to be essentially clonal. This assumption was challenged with the recent report of several homologous recombinations within the Tick-borne encephalitis virus (TBEV). We performed a thorough analysis of publicly available genomes in this group and found no compelling evidence for the previously identified recombinations. However, our results show for the first time that demonstrable recombination (i.e., with large statistical support and strong phylogenetic evidences) has occurred in the MTBFG, more specifically within the Louping ill virus lineage. Putative parents, recombinant strains and breakpoints were further tested for statistical significance using phylogenetic methods. We investigated the time of divergence between the recombinant and parental strains in a Bayesian framework. The recombination was estimated to have occurred during a window of 282 to 76 years before the present. By unravelling the temporal setting of the event, we adduce hypotheses about the ecological conditions that could account for the observed recombination. 相似文献
999.
Träger U Sierro S Djordjevic G Bouzo B Khandwala S Meloni A Mortensen M Simon AK 《PloS one》2012,7(4):e35005
The expression of melanoma-associated antigens (MAA) being limited to normal melanocytes and melanomas, MAAs are ideal targets for immunotherapy and melanoma vaccines. As MAAs are derived from self, immune responses to these may be limited by thymic tolerance. The extent to which self-tolerance prevents efficient immune responses to MAAs remains unknown. The autoimmune regulator (AIRE) controls the expression of tissue-specific self-antigens in thymic epithelial cells (TECs). The level of antigens expressed in the TECs determines the fate of auto-reactive thymocytes. Deficiency in AIRE leads in both humans (APECED patients) and mice to enlarged autoreactive immune repertoires. Here we show increased IgG levels to melanoma cells in APECED patients correlating with autoimmune skin features. Similarly, the enlarged T cell repertoire in AIRE(-/-) mice enables them to mount anti-MAA and anti-melanoma responses as shown by increased anti-melanoma antibodies, and enhanced CD4(+) and MAA-specific CD8(+) T cell responses after melanoma challenge. We show that thymic expression of gp100 is under the control of AIRE, leading to increased gp100-specific CD8(+) T cell frequencies in AIRE(-/-) mice. TRP-2 (tyrosinase-related protein), on the other hand, is absent from TECs and consequently TRP-2 specific CD8(+) T cells were found in both AIRE(-/-) and AIRE(+/+) mice. This study emphasizes the importance of investigating thymic expression of self-antigens prior to their inclusion in vaccination and immunotherapy strategies. 相似文献
1000.
Munaut C Lorquet S Pequeux C Coulon C Le Goarant J Chantraine F Noël A Goffin F Tsatsaris V Subtil D Foidart JM 《PloS one》2012,7(3):e33475