Nod2-dependent regulation of innate and adaptive immunity in the intestinal tract     

Kobayashi KS  Chamaillard M  Ogura Y  Henegariu O  Inohara N  Nuñez G  Flavell RA 《Science (New York, N.Y.)》2005,307(5710):731-734

The gene encoding the Nod2 protein is frequently mutated in Crohn's disease (CD) patients, although the physiological function of Nod2 in the intestine remains elusive. Here we show that protective immunity mediated by Nod2 recognition of bacterial muramyl dipeptide is abolished in Nod2-deficient mice. These animals are susceptible to bacterial infection via the oral route but not through intravenous or peritoneal delivery. Nod2 is required for the expression of a subgroup of intestinal anti-microbial peptides, known as cryptdins. The Nod2 protein is thus a critical regulator of bacterial immunity within the intestine, providing a possible mechanism for Nod2 mutations in CD.  相似文献   

Brightening depression     

Wirz-Justice A  Terman M  Oren DA  Goodwin FK  Kripke DF  Whybrow PC  Wisner KL  Wu JC  Lam RW  Berger M  Danilenko KV  Kasper S  Smeraldi E  Takahashi K  Thompson C  van den Hoofdakker RH 《Science (New York, N.Y.)》2004,303(5657):467-469

  相似文献   

Parasite selection for immunogenetic optimality     

Wegner KM  Kalbe M  Kurtz J  Reusch TB  Milinski M 《Science (New York, N.Y.)》2003,301(5638):1343

  相似文献   

Translational operator of mRNA on the ribosome: how repressor proteins exclude ribosome binding     

Jenner L  Romby P  Rees B  Schulze-Briese C  Springer M  Ehresmann C  Ehresmann B  Moras D  Yusupova G  Yusupov M 《Science (New York, N.Y.)》2005,308(5718):120-123

The ribosome of Thermus thermophilus was cocrystallized with initiator transfer RNA (tRNA) and a structured messenger RNA (mRNA) carrying a translational operator. The path of the mRNA was defined at 5.5 angstroms resolution by comparing it with either the crystal structure of the same ribosomal complex lacking mRNA or with an unstructured mRNA. A precise ribosomal environment positions the operator stem-loop structure perpendicular to the surface of the ribosome on the platform of the 30S subunit. The binding of the operator and of the initiator tRNA occurs on the ribosome with an unoccupied tRNA exit site, which is expected for an initiation complex. The positioning of the regulatory domain of the operator relative to the ribosome elucidates the molecular mechanism by which the bound repressor switches off translation. Our data suggest a general way in which mRNA control elements must be placed on the ribosome to perform their regulatory task.  相似文献   

Potential for carbon sequestration after biochar-P fertilizer application: A biological and chemical assessment     

Bernardo M. M. N. Borges  Matheus Sampaio C. Barreto  Paulo S. Pavinato  Henrique C. J. Franco  João Luís Nunes Carvalho  Mathias Strauss  Saran Sohi 《European Journal of Soil Science》2023,74(4):e13400

Innovation is required on many fronts in agriculture, not only to improve nutrient use efficiency but also to mitigate the effects of climate change. Our previous studies presented the high agronomic efficiency of an experimental phosphate fertilizer using a biochar-matrix, called ‘BioFert’. However, the efficiency of BioFert for soil carbon sequestration goals has not yet been evaluated. We incubated BioFert and initial raw sugarcane-biochar over 56 days in two soils (i.e., Ferralsol and Alisol) and measured the total CO₂ and δ¹³C-CO₂ to quantify the contribution of native soil organic matter, sugarcane-biochar, or BioFert to carbon mineralization. There was no significant difference in cumulative CO₂ release between BioFert and the control (without carbon addition), and BioFert was less mineralized than carbon from sugarcane-biochar regardless of soil type. In addition, accelerated aging by thermal oxidation of these carbon sources revealed that more than 80% of BioFert-carbon was prevented from accelerated mineralization, while sugarcane-biochar achieved ~80% of carbon mineralization. The residual solids after oxidation were analysed by X-ray photoelectron spectroscopy and indicated aliphatic/aromatic and carboxylic chemical bonds on the BioFert surface, which might offer new cation exchange sites over time. We conclude that BioFert is not only a phosphate fertilizer with high phosphorus use efficiency but also a stable source of carbon for soil carbon sequestration purposes.  相似文献   

Rice yield and productivity gaps in irrigated systems of the forest zone of Côte d'Ivoire     

Mathias Becker  David E. Johnson 《Field Crops Research》1999,60(3):367-208

Much of the rapidly growing demand for rice in West Africa will be met from increased production in irrigated lowlands, which cover about 12% of the regional rice-growing area. A large potential for expansion of irrigated areas exists particularly in the inland valleys of the humid forest zone. Current production is characterized by large variability in productivity, management practices and production constraints. Quantifying the variability in rice yield and identifying the determining factors are prerequisites to the development of site-specific recommendations and to improved targeting of technologies. Diagnostic on-farm trials were conducted on 64 irrigated lowland fields in the humid forest zone of southern Côte d'Ivoire, in 1995–1996. This was a part of the regional gradient study of irrigated systems from the desert margin to the humid forest zone. Cropping calendars, field operations and input use were monitored. Weed biomass, rice N uptake, and grain yield were determined in farmers' fields as well as in super-imposed, researcher-managed subplots (clean weeding, no N control, and mineral fertilizer N application). Rice yield potential was simulated by using the Oryza-S crop growth model. Yield losses were attributed to management factors based on performance of rice in researcher-managed subplots (management-related yield gap) and by multiple regression with management options. Grain yields varied between 0.2 and 7.3 Mg ha⁻¹ with mean yields of 3.2 in partially and 4.2 Mg ha⁻¹ in fully irrigated systems, 44% and 57% of the potential yield of 7.3 Mg ha⁻¹, respectively. Age of seedlings at transplanting, timeliness of operations and application of P fertilizer were correlated to yield and explained 60% of the observed variability. Grain yield was correlated with N uptake (r² = 0.93^***) but not with N application rate. Split application of mineral fertilizer N was associated with a 0.48 Mg ha⁻¹ yield increase (p = 0.002), regardless of the quantity applied. Additional weeding increased yield only in systems with imperfect irrigation. Weed biomass was reduced with improved water control and it increased with age of seedlings at transplanting, and was higher in direct-seeded than in transplanted rice. Echinochloa spp. were the most common weeds in fully irrigated systems and Panicum laxum was more common in the imperfectly irrigated fields. While improved water management was associated with substantial rice yield increases (1.16 Mg ha⁻¹), the timeliness of transplanting, weeding and N fertilization appears to be the key to increased rice yields in the forest zone of West Africa.  相似文献