Herbaceous layer determines the relationship between soil respiration and photosynthesis in a shrub-dominated desert plant community

Plant and Soil - Although the linkages between aboveground photosynthates production and belowground respiration processes have been well studied, doubts remain as to the extent that photosynthate...     

The effects of long-term fertilization on the accumulation of organic carbon in the deep soil profile of an oasis farmland

Background and aims

Deeper soils represent a poorly understood, but potentially important, sink for carbon sequestration. The objective of this study was to determine the effects of long-term fertilization on soil organic carbon (SOC), its labile fractions and aggregate-associated carbon throughout a 0–3 m soil profile.

Methods

The investigation was conducted in a field experiment started in 1990 in an oasis farmland cropped with winter wheat. The following treatments were compared with the desert from which the oasis was created: CK (no fertilizer), NPK, N2P2K, NPKR, and N2P2R2 (“2” for double fertilizer and “R” for straw residue)

Results

SOC contents increased by 14–56 % in the topsoil (0–0.2 m), but decreased by 15–22 % in the subsoil (0.2–0.6 m) under all fertilizer treatments. In the deep layer (0.6–3 m) there were significant differences between the treatments: SOC decreased by 5–9 % in treatments without straw, but increased by 4–9 % in treatments with straw. Labile fractions (particulate organic carbon and light fraction organic carbon) also showed similar trends. Both the fertilizer and CK treatments led to an increase in the amount of macro-aggregates (>0.25 mm), especially small macro-aggregates (0.25–2 mm), throughout the soil profile. SOC content was highest in the macro-aggregates, intermediate in the silt + clay fraction (<0.053 mm), and lowest in the micro-aggregates (0.25–0.053 mm). However, 44–87 % of total SOC was stored in the silt + clay fraction, especially in the deep layer (at least 80 %).

Conclusions

After 20 years of fertilizer applications, difference in SOC mainly occurred in the deep layer, and preservation of SOC in the silt + clay fraction appeared to be a prerequisite for soil-carbon sequestration. Applying inorganic fertilizer alone decreased SOC content in the silt + clay fraction in the deep layer, while the combined applications with straw resulted in higher SOC content in the silt + clay fraction in that layer, which turned out to be the main mechanism for increasing SOC content. Our study indicated that applying straw with inorganic fertilizer is the best practice for carbon sequestration, which occurred mainly in the deep soil layer.     

Modification of donor lymphocyte infusion: how to improve the outcome?

<正>Even after allogeneic hematopoietic stem cell transplantation(HSCT), which has been acknowledged as a curative procedure, relapse of leukemia remains the leading cause of death following transplantation and is a disappointment to transplant physicians. Leukemic relapse occurs due to leukemia cell escape from immune-mediated killing (immune escape) by pre-transplantation conditioning and post-transplantation immune control. Immune exhaustion of donor T     

The protease-sensitive N-terminal polybasic region of prion protein modulates its conversion to the pathogenic prion conformer

Conversion of normal prion protein (PrP^C) to the pathogenic PrP^Sc conformer is central to prion diseases such as Creutzfeldt–Jakob disease and scrapie; however, the detailed mechanism of this conversion remains obscure. To investigate how the N-terminal polybasic region of PrP (NPR) influences the PrP^C-to-PrP^Sc conversion, we analyzed two PrP mutants: ΔN6 (deletion of all six amino acids in NPR) and Met4-1 (replacement of four positively charged amino acids in NPR with methionine). We found that ΔN6 and Met4-1 differentially impacted the binding of recombinant PrP (recPrP) to the negatively charged phospholipid 1-palmitoyl-2-oleoylphosphatidylglycerol, a nonprotein cofactor that facilitates PrP conversion. Both mutant recPrPs were able to form recombinant prion (recPrP^Sc) in vitro, but the convertibility was greatly reduced, with ΔN6 displaying the lowest convertibility. Prion infection assays in mammalian RK13 cells expressing WT or NPR-mutant PrPs confirmed these differences in convertibility, indicating that the NPR affects the conversion of both bacterially expressed recPrP and post-translationally modified PrP in eukaryotic cells. We also found that both WT and mutant recPrP^Sc conformers caused prion disease in WT mice with a 100% attack rate, but the incubation times and neuropathological changes caused by two recPrP^Sc mutants were significantly different from each other and from that of WT recPrP^Sc. Together, our results support that the NPR greatly influences PrP^C-to-PrP^Sc conversion, but it is not essential for the generation of PrP^Sc. Moreover, the significant differences between ΔN6 and Met4-1 suggest that not only charge but also the identity of amino acids in NPR is important to PrP conversion.     

Expressed sequence tags from the zhikong scallop (Chlamys farreri): Discovery and annotation of host-defense genes

A high-quality cDNA library was constructed from whole body tissues of the zhikong scallop, Chlamys farreri, challenged by Listonella anguillarum. A total of 5720 clones were sequenced, yielding 5123 expressed sequence tags (ESTs). Among the 3326 unique genes identified, 2289 (69%) genes had no significant (E-value < 1e?5) matches to known sequences in public databases and 194 (6%) matched proteins of unknown functions. The remaining 843 (25%) genes that exhibited homology with genes of known functions, showed broad involvement in metabolic processes (31%), cell structure and motility (20%), gene and protein expression (12%), cell signaling and cell communication (8%), cell division (4%), and notably, 25% of those genes were related to immune function. They included stress response genes, complement-like genes, proteinase and proteinase inhibitors, immune recognition receptors and immune effectors. The EST collection obtained in this study provides a useful resource for gene discovery and especially for the identification of host-defense genes and systems in scallops and other molluscs.     

CXCR4的抑制性多肽对乳腺癌细胞CXCR4和HER-2表达及HERCEPTIN药物敏感性的影响

目的 探讨CXCR4抑制性多肽对人乳腺癌细胞株SKBR3膜受体HER-2和CXCR4的蛋白表达及其对Herceptin药物敏感性的影响.方法 抑制性多肽、Herceptin单独或联合处理乳腺癌SKBR3细胞24、48h后,用MTT法观测SKBR3细胞的增殖抑制效应;Weatern blot和免疫纽化法检测SKBR3细胞中CXCR4和HER-2蛋白表达;RT-PCR检测HER-2、CXCR4 mRNA的表达,流式细胞仪检测细胞周期的变化.结果 多肽和Herceptin可不同程度地下调人乳腺癌细胞SKBR3中CXCR4和HER-2的蛋白表达.多肽对细胞生长抑制不明显,与Herceptin联合用药后,生长抑制率高于对照组和Herceptin单独用药组(P<0.001),48h生长抑制率为57.94%±5.3,且呈时问依赖(P<0.05),Herceptin单独作用SKBR3-细胞,细胞周期阻滞于G0/GI期,并且S期的比例减少,与多肽联合作用后,细胞周期又进一步阻滞于G2/M期,S期细胞进一步降低.结论 抑制性多肽能不同程度地下调膜受体HER-2和CXCR4的表达,提高人乳腺癌细胞株SKBR3对Herceptin药物的敏感性.     

Expression and characterization of earthworm Eisenia foetida lumbrokinase-3 in Pichia pastoris

Lumbrokinase-3 (LK-3, AY438622), first cloned from the earthworm Eisenia foetida in our laboratory, is a component of earthworm fibrinolytic enzymes. In this study, cDNA encoding the LK-3 gene was sub-cloned into yeast pPIC9K expression vector and transformed into the Pichia pastoris GS115 cells by electroporation. High level expression of LK-3 in yeast cells was confirmed with a different induction time. The activity of expressed LK-3 was observed in fibrin plates. In addition, the expressed LK-3 protein could dissolve fibrinogen and bovine serum albumin. The use of this system for the high level production of biological protein is implicated from this study.     

Persistent protease-activated receptor 4 signaling mediates thrombin-induced microglial activation

We have previously reported that thrombin, the ultimate serine protease in the coagulation cascades, is a proinflammatory agent that causes proliferation and activation of brain microglial cells. However, participation of its principal receptor, the protease-activated receptor 1 (PAR1) appears to be limited to promoting microglial proliferation and not induction of inflammatory mediators. In the present study, we now report that thrombin action in promoting inflammatory mediators from brain microglia is mediated through another thrombin receptor, PAR4. Here we show that the PAR4 agonist peptide (PAR4AP, GYPGKF), but not the PAR1AP (TRAP, SFLLRN), induced tumor necrosis factor-alpha (TNF-alpha) production not only in cultured murine microglial cells in vitro but also in rat cortex in vivo. Down-regulation of PAR4 expression in microglial cultures by a specific antisense, but not a sense, oligonucleotide reduced PAR4AP-induced TNF-alpha. Mechanistic studies indicated that, in comparison with PAR1 signaling, prolonged increase of [Ca2+]i and phosphorylation of p44/42 mitogen-activated protein kinases, as well as NFkappaB activation may be responsible for PAR4AP-induced TNF-alpha production in microglia. Taken together, these results demonstrate that PAR4 activation mediates the potentially detrimental effects of thrombin on microglia, implying that perspectives of exploiting PAR1 as a potential anti-inflammatory target should be shifted toward PAR4 as a much more specific therapeutic target in brain inflammatory conditions associated with neurotrauma and neurodegenerations.     

Genome-Wide Gene Expression Profiles in Lung Tissues of Pig Breeds Differing in Resistance to Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) is an infectious disease characterized by severe reproductive deficiency in pregnant sows, typical respiratory symptoms in piglets, and high mortality rate of piglets. In this study, we employed an Affymetrix microarray chip to compare the gene expression profiles of lung tissue samples from Dapulian (DPL) pigs (a Chinese indigenous pig breed) and Duroc×Landrace×Yorkshire (DLY) pigs after infection with PRRSV. During infection with PRRSV, the DLY pigs exhibited a range of clinical features that typify the disease, whereas the DPL pigs showed only mild signs of the disease. Overall, the DPL group had a lower percentage of CD4⁺ cells and lower CD4⁺/CD8⁺ratios than the DLY group (p<0.05). For both IL-10 and TNF-α, the DLY pigs had significantly higher levels than the DPL pigs (p<0.01). The DLY pigs have lower serum IFN-γ levels than the DPL pigs (p<0.01). The serum IgG levels increased slightly from 0 dpi to 7 dpi, and peaked at 14 dpi (p<0.0001). Microarray data analysis revealed 16 differentially expressed (DE) genes in the lung tissue samples from the DLY and DPL pigs (q≤5%), of which LOC100516029 and LOC100523005 were up-regulated in the PRRSV-infected DPL pigs, while the other 14 genes were down-regulated in the PRRSV-infected DPL pigs compared with the PRRSV-infected DLY pigs. The mRNA expression levels of 10 out of the 16 DE genes were validated by real-time quantitative RT-PCR and their fold change was consistent with the result of microarray data analysis. We further analyzed the mRNA expression level of 8 differentially expressed genes between the DPL and DLY pigs for both uninfected and infected groups, and found that TF and USP18 genes were important in underlying porcine resistance or susceptibility to PRRSV.     

Analysis of 2‐propanol in exhaled breath using in situ enrichment and cataluminescence detection

We report a simple gaseous sensor for the sensitive detection of trace 2‐propanol in exhaled breath using in situ enrichment and cataluminescence detection method on the surface of nanomaterials. The influences of heating voltage and absorption time on the CTL intensity were discussed, respectively. In the selected conditions, the linear range of 2‐propanol concentration is 60–600 ppbv and the detection of limit is 11 ppbv. Moreover, the lifetime and selectivity of the sensor were also investigated. It has the potential to diagnostic volatile organic compounds in human breath. Copyright © 2010 John Wiley & Sons, Ltd