Quantitative trait loci analysis for chlorophyll content of cucumber (Cucumis sativus L.) seedlings under low-light stress

An increase in chlorophyll content is an adaptive response to low-light stress and can be used to evaluate low-light tolerance. The effects of low-light stress (100 ìmol·m-2.s-1) on the chlorophyll content of cucumber (Cucumis sativus L.) were investigated in a set of 123 F2:3 lines in the seedling stage in the autumn of 2008 and spring of 2009. Quantitative trait loci (QTL) analysis was undertaken on the basis of a genetic linkage map of the corresponding F2 population that was constructed using composite interval mapping. F2:3-based QTL analysis of the chlorophyll-a (chl.a), chlorophyll-b (chl.b) and chlorophyll-a+b (chl.a+b) content in the 2 environments revealed 21 QTLs located on the linkage groups 1, 2, 3, 4, 6 and 7, which accounted for 4.8 - 17.3% of the phenotypic variation. In the spring of 2009, the total phenotypic variation among the F2:3 lines accounted for by the QTLs for chl.a, chl.b and chl.a+b were 44.5, 29.4 and39.0%, respectively. In the autumn of 2008, 11 QTLs were identified, which accounted for 4.8 - 14.9% of the observed phenotypic variation and an additive effect of -8.10 to 20.85. Four major-effect QTLs (chla2.1, chlb2.2, chlb3.1 and chla+b2.2) were detected under both conditions. The QTL information presented in this research, together with the data from our previous study on heredity of low-light tolerant traits, will facilitate the breeding of low-light-stress-resistant cucumbers

A reactor-scale CFD model of soot formation during high-temperature pyrolysis and gasification of biomass

Soot generation is an important problem in high-temperature biomass gasification, which results in both air pollution and the contamination of gasification equipment. Due to the complex nature of biomass materials and the soot formation process, it is still a challenge to fully understand and describe the mechanisms of tar evolution and soot generation at the reactor scale. This knowledge gap thus motivates the development of a comprehensive computational fluid dynamics (CFD) soot formation algorithm for biomass gasification, where the soot precursor is modeled using a component-based pyrolysis framework to distinguish cellulose, hemicellulose and lignin. The model is first validated with pyrolysis experiments from different research groups, after which the soot generation during biomass steam gasification in a drop-tube furnace is studied under different operating temperatures (900–1200 \ub0C) and steam/biomass ratios. Compared with the predictions based on a detailed tar conversion model, the current algorithm captures the soot generation more reasonably although a simplified tar model is used. Besides, the influence of biomass lignin content and the impact of tar and soot consumptions on the soot yield is quantitatively studied. Moreover, the impact of surface growth on soot formation is also discussed. The current work demonstrates the feasibility of the coupled multiphase flow algorithm in the prediction of soot formation during biomass gasification with strong heat/mass transfer effects. In conclusion, the model is thus a useful tool for the analysis and optimization of industrial-scaled biomass gasification

The Importance of Serine Phosphorylation of Ameloblastin on Enamel Formation

FAM20C is a newly identified kinase on the secretory pathway responsible for the phosphorylation of serine residues in the Ser-x-Glu/pSer motifs in several enamel matrix proteins. Fam20C-knockout mice showed severe enamel defects very similar to those in the ameloblastin (Ambn)–knockout mice, implying that phosphoserines may have a critical role in AMBN function. To test this hypothesis, we generated amelogenin (Amel) promoter-driven Ambn-transgenic mice, in which Ser⁴⁸, Ser²²⁶, and Ser²²⁷ were replaced by aspartic acid (designated as D-Tg) or alanines (designated as A-Tg). The negative charge of aspartic acid is believed to be able to mimic the phosphorylation state of serine, while alanine is a commonly used residue to substitute serine due to their similar structure. Using Western immunoblotting and quantitative polymerase chain reaction, the authors identified transgenic lines expressing transgenes somewhat higher (Tg+) or much higher (Tg++) than endogenous Ambn. The lower incisors collected from 7-d-old and 7-wk-old mice were analyzed by histology, scanning electron microscopy, immunohistochemistry, and Western immunoblotting to examine the morphology and microstructure changes in enamel, as well as the expression pattern of enamel matrix proteins. The A-Tg+ and A-Tg++ mice displayed severe enamel defects in spite of the expression level of transgenes, while the D-Tg+ and D-Tg++ mice showed minor to mild enamel defects, indicating that the D-Tg transgenes disturbed enamel formation less than the A-Tg transgenes did. Our results suggest that the phosphorylation state of serines is likely an essential component for the integrity of AMBN function

High-temperature pyrolysis modeling of a thermally thick biomass particle based on an MD-derived tar cracking model

Biomass pyrolysis in the thermally thick regime is an important thermochemical phenomenon encountered in many different types of reactors. In this paper, a particle-resolved algorithm for thermally thick biomass particle during high-temperature pyrolysis is established by using reactive molecular dynamics (MD) and computational fluid dynamics (CFD) methods. The temperature gradient inside the particle is computed with a heat transfer equation, and a multiphase flow algorithm is used to simulate the advection/diffusion both inside and outside the particle. Besides, to simulate the influence of intraparticle temperature gradient on the primary pyrolysis yields, a multistep kinetic scheme is used. Moreover, a new tar decomposition model is developed by reactive molecular dynamic simulations where every primary tar species in the multistep kinetic scheme cracks under high temperature. The integrated pyrolysis model is evaluated against a pyrolysis experiment of a centimeter-sized beech wood particle at 800 to 1050 \ub0C. The simulation results show a remarkable improvement in both light gas and tar yields compared with a simplified tar cracking model. Meanwhile, the MD tar cracking model also gives a more reasonable prediction of the species yield history, which avoids the appearance of unrealistically high peak values at the initial stage of pyrolysis. Based on the new results, the different roles of secondary tar cracking inside and outside the particle is studied. Finally, the model is also used to assess the influence of tar residence time and several other factors impacting the pyrolysis

Ablation of EIF5A2 induces tumor vasculature remodeling and improves tumor response to chemotherapy via regulation of matrix metalloproteinase 2 expression

Hepatocellular carcinoma (HCC) is a highly vascularized tumor with poor clinical outcome. Our previous work has shown that eukaryotic initiation factor 5A2 (EIF5A2) over-expression enhances HCC cell metastasis. In this study, EIF5A2 was identified to be an independent risk factor for poor disease-specific survival among HCC patients. Both in vitro and in vivo assays indicated that ablation of endogenous EIF5A2 inhibited tumor angiogenesis by reducing matrix metalloproteinase 2 (MMP-2) expression. Given that MMP-2 degrades collagen IV, a main component of the vascular basement membrane (BM), we subsequently investigated the effect of EIF5A2 on tumor vasculature remodeling using complementary approaches, including fluorescent immunostaining, transmission electron microscopy, tumor perfusion assays and tumor hypoxia assays. Taken together, our results indicate that EIF5A2 silencing increases tumor vessel wall continuity, increases blood perfusion and improves tumor oxygenation. Additionally, we found that ablation of EIF5A2 enhanced the chemosensitivity of HCC cells to 5-Fluorouracil (5-FU). Finally, we demonstrated that EIF5A2 might exert these functions by enhancing MMP-2 activity via activation of p38 MAPK and JNK/c-Jun pathways. Conclusion: This study highlights an important role of EIF5A2 in HCC tumor vessel remodeling and indicates that EIF5A2 represents a potential therapeutic target in the treatment of HCC.published_or_final_versio

PAHs contamination and bacterial communities in mangrove surface sediments of the Jiulong River Estuary, China

Sixteen sediment samples collected from eight transects in a mangrove swamp of the Jiulong River Estuary, Fujian, China were investigated for their content of polycyclic aromatic hydrocarbons (PAHs) and the biodegradation potential of the indigenous microorganisms. The bacterial community structures in the mangrove sediments and in enrichment cultures were also investigated. The results showed that the total PAHs concentration of mangrove sediments ranged from 280 to 1074 ng g(-1) dry weight, that the PAHs composition pattern in the mangrove sediments was dominated by high molecular weight PAH components (4-6 rings), and that Benzo[ghi]perylene and Indeno[1,2,3-cd]pyrene were the most dominant at different stations. Abundant PAH-degrading bacteria were found in all the stations, the values of phenanthrene-degrading bacteria ranged from 5.85 x 10(4) to 7.80 x 10(5) CFU g(-1) dry weight, fluoranthene-degrading bacteria ranged from 5.25 x 10(4) to 5.79 x 10(5) CFU g(-1) dry weight, pyrene-degrading bacteria ranged from 3.10 x 10(4) to 6.97 x 10(5) CFU g(-1) dry weight and the benzo(a)pyrene-degrading bacteria ranged from 5.25 x 10(4) to 7.26 x 10(5) CFU g(-1) dry weight. DGGE analysis of PCR-amplified 16S rDNA gene fragments confirmed that there was a remarkable shift in the composition of the bacterial community due to the addition of the different model PAH compound phenanthrene (three ring PAH), fluoranthene(four ring PAH), pyrene(four ring PAH) and benzo(a)pyrene(five ring PAH) during enrichment batch culture. Eleven strains were obtained with different morphology and different degradation ability. The presence of common bands for microbial species in the cultures and in the native mangrove sediment DNA indicated that these strains could be potential in situ PAH-degraders. (C) 2008 Elsevier Ltd. All rights reserved

A habituation account of change detection in same/different judgments

We investigated the basis of change detection in a short-term priming task. In two experiments, participants were asked to indicate whether or not a target word was the same as a previously presented cue. Data from an experiment measuring magnetoencephalography failed to find different patterns for “same” and “different” responses, consistent with the claim that both arise from a common neural source, with response magnitude defining the difference between immediate novelty versus familiarity. In a behavioral experiment, we tested and confirmed the predictions of a habituation account of these judgments by comparing conditions in which the target, the cue, or neither was primed by its presentation in the previous trial. As predicted, cue-primed trials had faster response times, and target-primed trials had slower response times relative to the neither-primed baseline. These results were obtained irrespective of response repetition and stimulus–response contingencies. The behavioral and brain activity data support the view that detection of change drives performance in these tasks and that the underlying mechanism is neuronal habituation

YARN PARAMETERS INFLUENCING THE KNITTABILITY OF HIGH-GRADE SPUN YARNS

Noncollinear magnetism can play an important role in multiferroic materials but is relatively understudied in oxide heterostructures compared to their bulk counterparts. Using variable temperature magnetometry and neutron diffraction, we demonstrate the presence of helical magnetic ordering in CaMn7O12 and Ca1−xSrxMn7O12 (for x up to 0.51) thin films. Consistent with bulk Ca1−xSrxMn7O12, the net magnetization increases with Sr doping. Neutron diffraction confirms that the helical magnetic structure remains incommensurate at all values of x, while the fundamental magnetic wavevector increases upon Sr substitution. This result demonstrates a chemical-based approach for tuning helical magnetism in quadruple perovskite films and enables future studies of strain and interfacial effects on helimagnetism in oxide heterostructures

Maternal corticotropin-releasing hormone is associated with LEP DNA methylation at birth and in childhood: an epigenome-wide study in Project Viva

BackgroundCorticotropin-releasing hormone (CRH) plays a central role in regulating the secretion of cortisol which controls a wide range of biological processes. Fetuses overexposed to cortisol have increased risks of disease in later life. DNA methylation may be the underlying association between prenatal cortisol exposure and health effects. We investigated associations between maternal CRH levels and epigenome-wide DNA methylation of cord blood in offsprings and evaluated whether these associations persisted into mid-childhood.MethodsWe investigated mother-child pairs enrolled in the prospective Project Viva pre-birth cohort. We measured DNA methylation in 257 umbilical cord blood samples using the HumanMethylation450 Bead Chip. We tested associations of maternal CRH concentration with cord blood cells DNA methylation, adjusting the model for maternal age at enrollment, education, maternal race/ethnicity, maternal smoking status, pre-pregnancy body mass index, parity, gestational age at delivery, child sex, and cell-type composition in cord blood. We further examined the persistence of associations between maternal CRH levels and DNA methylation in children's blood cells collected at mid-childhood (n = 239, age: 6.7-10.3 years) additionally adjusting for the children's age at blood drawn.ResultsMaternal CRH levels are associated with DNA methylation variability in cord blood cells at 96 individual CpG sites (False Discovery Rate <0.05). Among the 96 CpG sites, we identified 3 CpGs located near the LEP gene. Regional analyses confirmed the association between maternal CRH and DNA methylation near LEP. Moreover, higher maternal CRH levels were associated with higher blood-cell DNA methylation of the promoter region of LEP in mid-childhood (P < 0.05, β = 0.64, SE = 0.30).ConclusionIn our cohort, maternal CRH was associated with DNA methylation levels in newborns at multiple loci, notably in the LEP gene promoter. The association between maternal CRH and LEP DNA methylation levels persisted into mid-childhood