Response of CH4 and N2O Emissions and Wheat Yields to Tillage Method Changes in the North China Plain

The objective of this study was to quantify soil methane (CH₄) and nitrous oxide (N₂O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH₄ and N₂O flux and soil temperature, moisture, NH₄ ⁺-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH₄ appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N₂O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH₄ and N₂O increased by approximately 0.05 kg CO₂ ha⁻¹ for HTS, 0.02 kg CO₂ ha⁻¹ for RTS and 0.23 kg CO₂ ha⁻¹ for NTS. Soil temperature, moisture, SOC, NH₄ ⁺-N and pH also changed after conversion to subsoiling. These changes were correlated with CH₄ uptake and N₂O emissions. However, there was no significant correlation between N₂O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region.     

T cell-specific siRNA delivery suppresses HIV-1 infection in humanized mice

Evaluation of the therapeutic potential of RNAi for HIV infection has been hampered by the challenges of siRNA delivery and lack of suitable animal models. Using a delivery method for T cells, we show that siRNA treatment can dramatically suppress HIV infection. A CD7-specific single-chain antibody was conjugated to oligo-9-arginine peptide (scFvCD7-9R) for T cell-specific siRNA delivery in NOD/SCIDIL2rgamma-/- mice reconstituted with human lymphocytes (Hu-PBL) or CD34+ hematopoietic stem cells (Hu-HSC). In HIV-infected Hu-PBL mice, treatment with anti-CCR5 (viral coreceptor) and antiviral siRNAs complexed to scFvCD7-9R controlled viral replication and prevented the disease-associated CD4 T cell loss. This treatment also suppressed endogenous virus and restored CD4 T cell counts in mice reconstituted with HIV+ peripheral blood mononuclear cells. Moreover, scFvCD7-9R could deliver antiviral siRNAs to naive T cells in Hu-HSC mice and effectively suppress viremia in infected mice. Thus, siRNA therapy for HIV infection appears to be feasible in a preclinical animal model.     

Two C-terminal ankyrin repeats form the minimal stable unit of the ankyrin repeat protein p18INK4c

Ankyrin repeat proteins (ARPs) appear to be abundant in organisms from all phyla, and play critical regulatory roles, mediating specific interactions with target biomolecules and thus ordering the sequence of events in diverse cellular processes. ARPs possess a non-globular scaffold consisting of repeating motifs named ankyrin (ANK) repeats, which stack on each other. The modular architecture of ARPs provides a new paradigm for understanding protein stability and folding mechanisms. In the present study, the stability of various C-terminal fragments of the ARP p18^INK4c was investigated by all-atomic 450 ns molecular dynamics (MD) simulations in explicit water solvent. Only motifs with at least two ANK repeats made stable systems in the available timescale. All smaller fragments were unstable, readily losing their native fold and α-helical content. Since each non-terminal ANK repeat has two hydrophobic sides, we may hypothesize that at least one hydrophobic side must be fully covered and shielded from the water as a necessary, but not sufficient, condition to maintain ANK repeat stability. Consequently, at least two ANK repeats are required to make a stable ARP. Figure Structure of the p18INK4c protein (PDB entry 1IHB, chain B), which is a member of the cyclin-dependent kinase inhibitor (INK) tumor suppressor family with five ankyrin (ANK) repeat modules. The figure was generated by PyMol Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Detection for folding of the thrombin binding aptamer using label-free electrochemical methods

The folding of aptamer immobilized on an Au electrode was successfully detected using label-free electrochemical methods. A thrombin binding DNA aptamer was used as a model system in the presence of various monovalent cations. Impedance spectra showed that the extent to which monovalent cations assist in folding of aptamer is ordered as K(+) > NH(4)(+) > Na(+) > Cs(+). Our XPS analysis also showed that K(+) and NH(4)(+) caused a conformational change of the aptamer in which it forms a stable complex with these monovalent ions. Impedance results for the interaction between aptamer and thrombin indicated that thrombin interacts more with folded aptamer than with unfolded aptamer. The EQCM technique provided a quantitative analysis of these results. In particular, the present impedance results showed that thrombin participates a folding of aptamer to some extent, and XPS analysis confirmed that thrombin stabilizes and induces the folding of aptamer.     

Dynamics of trigger factor interaction with translating ribosomes

In all organisms ribosome-associated chaperones assist early steps of protein folding. To elucidate the mechanism of their action, we determined the kinetics of individual steps of the ribosome binding/release cycle of bacterial trigger factor (TF), using fluorescently labeled chaperone and ribosome-nascent chain complexes. Both the association and dissociation rates of TF-ribosome complexes are modulated by nascent chains, whereby their length, sequence, and folding status are influencing parameters. However, the effect of the folding status is modest, indicating that TF can bind small globular domains and accommodate them within its substrate binding cavity. In general, the presence of a nascent chain causes an up to 9-fold increase in the rate of TF association, which provides a kinetic explanation for the observed ability of TF to efficiently compete with other cytosolic chaperones for binding to nascent chains. Furthermore, a subset of longer nascent polypeptides promotes the stabilization of TF-ribosome complexes, which increases the half-life of these complexes from 15 to 50 s. Nascent chains thus regulate their folding environment generated by ribosome-associated chaperones.     

DNA marker analysis for pyramided of Fusarium head blight (FHB) resistance QTLs from different germplasm

A pyramided FHB resistance line of wheat (WSY) was previously developed from three FHB resistant cultivars (Sumai 3, Wangshuibai, and Nobeokabouzu) in the Jiangsu Academy of Agricultural Sciences, China. In the present study, we analyzed the genetic relationship between WSY and the three parental cultivars using DNA markers in order to clarify how many and which resistance genes had accumulated in WSY. We analyzed 282 DNA markers from the 21 wheat chromosomes. WSY was found to include different chromosome regions that harbored putative FHB QTLs of the three parental germplasm. Haplotypes of DNA markers on these QTL regions revealed that the 1BL, 2BL, 5AS, and 7AL QTL regions were from Sumai 3, the 2AS, 2DS, 3AS, and 6BS QTL regions were from Wangshuibai, and the 3BS QTL region was from Nobeokabouzu. This study showed that different resistance genes from the different resistant germplasm had indeed accumulated in WSY. WSY is a potential resistant resource for FHB resistance in wheat breeding programs.     

Pretreatment of textile dyeing wastewater using an anoxic baffled reactor

A study on pretreatment of textile dyeing wastewater was carried out using an anoxic baffled reactor (ABR) at wastewater temperatures of 5-31.1 degrees C. When hydraulic retention time (HRT) was 8h, the color of outflow of ABR was only 40 times at 5 degrees C and it could satisfy the professional discharge standard (grade-1) of textile and dyeing industry of China (GB4287-92). The total COD removal efficiency of ABR was 34.6%, 47.5%, 50.0%, 53.3%, 54.7% and 58.1% at 5, 9.7, 14.9, 19.7, 23.5 and 31.1 degrees C, respectively. Besides, after the wastewater being pre-treated by ABR when HRT was 6h and 8h, the BOD5/COD value rose from 0.30 of inflow to 0.46 of outflow and from 0.30 of inflow to 0.40 of outflow, respectively. Experimental results indicated that ABR was a very feasible process to decolorize and pre-treat the textile dyeing wastewater at ambient temperature. Moreover, a kinetic simulation of organic matter degradation in ABR at six different wastewater temperatures was carried through. The kinetic analysis showed the organic matter degradation was a first-order reaction. The reaction activation energy was 19.593 kJ mol(-1) and the temperature coefficient at 5-31.1 degrees C was 1.028.     

Cultivated plant species diversity in home gardens of an Amazonian peasant village in Northeastern Peru

Research on agrobiodiversity points to the importance of home gardens in situ conservation, yet few studies to date explicate the origins and dynamics of plant species diversity. In this paper, we examine inter-household variations in cultivated plant species diversity among house gardens in a traditional peasant community, near Iquitos, Peru. In-depth household interviews (n = 24) and garden/field surveys reveal that home gardens are clearly the site of highest plant diversity in farmers’ field portfolios, and that substantial differences exist in garden composition, plant diversity, and the sources of garden planting material across households. Statistical analyses indicate that home garden diversity is related strongly to specific garden characteristics, household socioeconomic features, and access to planting material including seeds, cuttings, and suckers. The role and implications of differential access to planting material in the development and maintenance of crop species diversity is signaled as an important theme for future study in economic botany.