Distribution of carbon isotope composition of modern soils on the Qinghai-Tibetan Plateau

This paper presents a large data set on carbon isotope composition (¹³C) of modern soils which were collected under the main vegetation communities along an altitude of 1250–5500m above sea level in the Qinghai-Tibetan Plateau. The ¹³C values of 198 samples range from –28.6 to –15.1 versus PDB and exhibit a clean relation to different vegetation communities from forest (–25.9±1.2) to shrub (–24.7±1.4), steppe (–23.1±1.3), alpine meadow (–23.6±0.7), alpine desert steppe (–21.3±1.6), and alpine desert (–18.9±2.5). We attributed the observed variability in ¹³C values to that the mean annual precipitation (MAP) and the mean annual temperature (MAT) are the main factors controlling the distribution of vegetation types in the Tibetan Plateau, which causes the change in carbon isotope composition of modern soils at any given altitude. The result of both linear and nonlinear regression analyses also confirms that MAP and MAT are the major factors affecting the ¹³C values of surface soils. In the absence of favorable moisture and temperature conditions, low pCO₂ alone is not sufficient to cause the distinct changes in carbon isotope composition of modern soils in the Tibetan Plateau. This study provides some fundamental information on the carbon isotope composition of terrestrial carbon pools and bears some practical significance for the use of carbon isotope data to document vegetation changes and environmental conditions of the high plateau in the past.     

A novel role for GADD45beta as a mediator of MMP-13 gene expression during chondrocyte terminal differentiation

The growth arrest and DNA damage-inducible 45beta (GADD45beta) gene product has been implicated in the stress response, cell cycle arrest, and apoptosis. Here we demonstrated the unexpected expression of GADD45beta in the embryonic growth plate and uncovered its novel role as an essential mediator of matrix metalloproteinase-13 (MMP-13) expression during terminal chondrocyte differentiation. We identified GADD45beta as a prominent early response gene induced by bone morphogenetic protein-2 (BMP-2) through a Smad1/Runx2-dependent pathway. Because this pathway is involved in skeletal development, we examined mouse embryonic growth plates, and we observed expression of Gadd45beta mRNA coincident with Runx2 protein in pre-hypertrophic chondrocytes, whereas GADD45beta protein was localized prominently in the nucleus in late stage hypertrophic chondrocytes where Mmp-13 mRNA was expressed. In Gadd45beta(-/-) mouse embryos, defective mineralization and decreased bone growth accompanied deficient Mmp-13 and Col10a1 gene expression in the hypertrophic zone. Transduction of small interfering RNA-GADD45beta in epiphyseal chondrocytes in vitro blocked terminal differentiation and the associated expression of Mmp-13 and Col10a1 mRNA in vitro. Finally, GADD45beta stimulated MMP-13 promoter activity in chondrocytes through the JNK-mediated phosphorylation of JunD, partnered with Fra2, in synergy with Runx2. These observations indicated that GADD45beta plays an essential role during chondrocyte terminal differentiation.     

Overexpression of Circular RNA ciRS‐7 Abrogates the Tumor Suppressive Effect of miR‐7 on Gastric Cancer via PTEN/PI3K/AKT Signaling Pathway

Gastric cancer (GC) has one of the highest mortality rates of malignancies globally. Currently, ciRS‐7, a novel circular RNA, has emerged as a potential sponge for miR‐7. However, few studies on ciRS‐7 in GC have been performed. In this study, we investigated the clinical significance and function of ciRS‐7 in GC. First, the expression levels of ciRS‐7 in 102 primary GC tissues and the matched para‐carcinoma tissues were evaluated and the clinical relevance was confirmed in an independent validation cohort (n = 154). Second, the effects of ciRS‐7 on miR‐7, PTEN, and PI3K were evaluated. Finally, the function of ciRS‐7 in GC was analyzed with cell lines and nude mice. The expression of ciRS‐7 was significantly upregulated in GC tissues compared with the matched para‐carcinoma tissues (P = 0.0023), and the upregulation of ciRS‐7 was linked to poor survival in the testing (P = 0.0143) and validation cohort (P = 0.0061). Multivariate survival analysis revealed that ciRS‐7 was probably an independent risk factor of overall survival (P < 0.05). Furthermore, overexpression of ciRS‐7 blocked the miR‐7‐induced tumor suppression in MGC‐803 and HGC‐27 cells and led to a more aggressive oncogenic phenotype, via antagonizing miR‐7‐mediated PTEN/PI3K/AKT pathway. ciRS‐7 may act as a prospective prognostic biological marker and a promising therapeutic target for GC. J. Cell. Biochem. 119: 440–446, 2018. © 2017 Wiley Periodicals, Inc.     

干湿交替灌溉下氮素形态对水稻花期光合及产量形成的影响

干湿交替灌溉(节水栽培)水稻较传统淹灌栽培表现出较高的生产潜力,其高产形成除因土壤水分改变有关外,可能还与根区水分变化引起的土壤氮素形态改变有关。该研究于2016年通过设置传统淹灌(W_1)和干湿交替灌溉(W_2)水分处理,以及氮素形态配比[硝态氮∶氨态氮=100∶0(N_1)、50∶50(N_2)和0∶100(N_3)]处理,并通过温室盆栽试验探讨水分与氮素形态互作对水稻花期光合生理及产量形成的影响。结果表明:(1)W_2水分处理产量及其构成因子、光合生产能力、收获指数、氮素收获指数以及氮素籽粒生产效率均显著高于W_1处理,其N素累积量略低于W_1处理。(2)在不同氮素形态之间,N_2处理的产量水平显著高于N_3和N_1处理,这主要是N_2处理加强了水稻物质转运以及光合生产能力,其中叶片含氮量和N素浓度提高可能是N_2处理呈现出高光合性能的重要原因。(3)氮素利用效率以N_1处理最高,随后依次分别为N_2和N_3处理。研究发现,土壤水分与氮素形态对促进水稻产量、产量构成因子、收获指数等形成均存在显著的互作效应,且W_2N_2处理的效应较其他处理更明显。     

怀山药种质资源的包埋玻璃化超低温保存与植株再生

通过对怀山药(Dioscorea opposita)种质资源的包埋玻璃化超低温保存与植株再生进行研究,结果表明:将低温下锻炼7天的怀山药试管苗带芽茎段放入预培养基中,低温下培养3天,然后在室温下用3%的海藻酸钠和0.5mol·L-1CaCl2包埋,包埋珠用MS+0.2mol·L-1蔗糖+2mol·L-1甘油+50g·L-1二甲基亚砜在0°C下装载60分钟,用30%甘油+15%乙二醇+10%二甲基亚砜+15%聚乙二醇+0.4mol·L-1蔗糖在0°C下脱水60分钟,迅速投入液氮,24小时后立即用40°C水浴快速化冻,再用MS+0.5mol·L-1蔗糖溶液洗涤2次,转入再生培养基中培养,可获得再生植株。再生植株成活率因基因型而异,铁棍山药、太谷山药、怀庆1号山药和B号山药的成活率分别为64.29%、49.21%、13.11%和39.81%。     

A CRISPR–Cas9 system for multiple genome editing and pathway assembly in Candida tropicalis

Genetic manipulation is among the most important tools for synthetic biology; however, modifying multiple genes is extremely time-consuming and can sometimes be impossible when dealing with gene families. Here, we present a clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated protein 9 (Cas9) system for use in the diploid yeast Candida tropicalis that is vastly superior to traditional techniques. This system enables the rapid and reliable introduction of multiple genetic deletions or mutations, as well as a stable expression using an integrated CRISPR–Cas9 cassette or a transient CRISPR–Cas9 cassette, together with a short donor DNA. We further show that the system can be used to promote the in vivo assembly of multiple DNA fragments and their stable integration into a target locus (or loci) in C. tropicalis. Based on this system, we present a platform for the biosynthesis of β-carotene and its derivatives. These results enable the practical application of C. tropicalis and the application of the system to other organisms.     

siRNA Targeting the 2Apro Genomic Region Prevents Enterovirus 71 Replication In Vitro

Enterovirus 71 (EV71) is the most important etiological agent of hand, foot, and mouth disease (HFMD) in young children, which is associated with severe neurological complications and has caused significant mortalities in recent HFMD outbreaks in Asia. However, there is no effective antiviral therapy against EV71. In this study, RNA interference (RNAi) was used as an antiviral strategy to inhibit EV71 replication. Three small interfering RNAs (siRNAs) targeting the 2A^pro region of the EV71 genome were designed and synthesized. All the siRNAs were transfected individually into rhabdomyosarcoma (RD) cells, which were then infected with strain EV71-2006-52-9. The cytopathic effects (CPEs) in the infected RD cells, cell viability, viral titer, and viral RNA and protein expression were examined to evaluate the specific viral inhibition by the siRNAs. The results of cytopathogenicity and MTT tests indicated that the RD cells transfected with the three siRNAs showed slight CPEs and significantly high viability. The 50% tissue culture infective dose (TCID₅₀) values demonstrated that the viral titer of the groups treated with three siRNAs were lower than those of the control groups. qRT–PCR and western blotting revealed that the levels of viral RNA and protein in the RD cells treated with the three siRNAs were lower than those in the controls. When RD cells transfected with siRNAs were also infected with strain EV71-2008-43-16, the expression of the VP1 protein was significantly inhibited. The levels of interferon α (IFN-α) and IFN-β did not differ significantly in any group. These results suggest that siRNAs targeting the 2A^pro region of the EV71 genome exerted antiviral effects in vitro.