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| 2. |
- Grimsholm, Ola, 1979, et al.
(författare)
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Absence of surrogate light chain results in spontaneous autoreactive germinal centres expanding V(H)81X-expressing B cells
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Random recombination of antibody heavy- and light-chain genes results in a diverse B-cell receptor (BCR) repertoire including self-reactive BCRs. However, tolerance mechanisms that prevent the development of self-reactive B cells remain incompletely understood. The absence of the surrogate light chain, which assembles with antibody heavy chain forming a pre-BCR, leads to production of antinuclear antibodies (ANAs). Here we show that the naive follicular B-cell pool is enriched for cells expressing prototypic ANA heavy chains in these mice in a non-autoimmune background with a broad antibody repertoire. This results in the spontaneous formation of T-cell-dependent germinal centres that are enriched with B cells expressing prototypic ANA heavy chains. However, peripheral tolerance appears maintained by selection thresholds on cells entering the memory B-cell and plasma cell pools, as exemplified by the exclusion of cells expressing the intrinsically self-reactive V(H)81X from both pools.
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| 3. |
- Hu, Hai-Xi, et al.
(författare)
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Structural insights into HetR-PatS interaction involved in cyanobacterial pattern formation
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The one-dimensional pattern of heterocyst in the model cyanobacterium Anabaena sp. PCC 7120 is coordinated by the transcription factor HetR and PatS peptide. Here we report the complex structures of HetR binding to DNA, and its hood domain (HetR(Hood)) binding to a PatS-derived hexapeptide (PatS6) at 2.80 and 2.10 angstrom, respectively. The intertwined HetR dimer possesses a couple of novel HTH motifs, each of which consists of two canonical alpha-helices in the DNA-binding domain and an auxiliary alpha-helix from the flap domain of the neighboring subunit. Two PatS6 peptides bind to the lateral clefts of HetR(Hood), and trigger significant conformational changes of the flap domain, resulting in dissociation of the auxiliary alpha-helix and eventually release of HetR from the DNA major grove. These findings provide the structural insights into a prokaryotic example of Turing model.
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| 4. |
- Ren, Bo, et al.
(författare)
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An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols
- 2016
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Ingår i: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 22:7, s. 2481-2486
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Tidskriftsartikel (refereegranskat)abstract
- In this study, [Fe(dibm)(3)] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.
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| 5. |
- Zhou, Guoyi, et al.
(författare)
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Climate and litter C/N ratio constrain soil organic carbon accumulation
- 2019
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Ingår i: National Science Review. - : Oxford University Press (OUP). - 2095-5138 .- 2053-714X. ; 6:4, s. 746-757
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic carbon (SOC) plays critical roles in stabilizing atmospheric CO2 concentration, but the mechanistic controls on the amount and distribution of SOC on global scales are not well understood. In turn, this has hampered the ability to model global C budgets and to find measures to mitigate climate change. Here, based on the data from a large field survey campaign with 2600 plots across China's forest ecosystems and a global collection of published data from forested land, we find that a low litter carbon-to-nitrogen ratio (C/N) and high wetness index (P/PET, precipitation-to-potential-evapotranspiration ratio) are the two factors that promote SOC accumulation, with only minor contributions of litter quantity and soil texture. The field survey data demonstrated that high plant diversity decreased litter C/N and thus indirectly promoted SOC accumulation by increasing the litter quality. We conclude that any changes in plant-community composition, plant-species richness and environmental factors that can reduce the litter C/N ratio, or climatic changes that increase wetness index, may promote SOC accumulation. The study provides a guideline for modeling the carbon cycle of various ecosystem scales and formulates the principle for land-based actions for mitigating the rising atmospheric CO2 concentration.
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