绿色木霉组蛋白去乙酰化酶编码基因TvRpd3在木霉生物防治作用中的功能分析

【目的】本文借助基因编辑技术在具有生物防治潜力的绿色木霉(Trichoderma viride)中敲除组蛋白去乙酰化酶编码基因TvRpd3,来研究TvRpd3基因及其编码蛋白在提高木霉病原菌拮抗能力中的作用。【方法】利用融合PCR和同源重组策略构建了TvRpd3基因缺失的突变菌株,通过对峙培养、表型观察、免疫组化检测、代谢组学分析等系统比较TvRpd3基因敲除前后菌株的组蛋白乙酰化修饰水平、次级代谢产物合成、病原菌拮抗能力以及田间防治效果等。【结果】与野生型菌株相比,缺失TvRpd3基因的木霉工程菌(?TvRpd3)对多种病原菌表现出了更强的对峙抑制效果,其所产的发酵液对小麦白粉病、烟草黑胫病和番茄枯萎病的防治效果分别提高了62.27%、57.45%和70.71%。同时,敲除TvRpd3基因也显著改变了木霉工程菌所产次级代谢产物的种类和产量,抗生性物质的产量大幅提高。【结论】绿色木霉TvRpd3基因及其介导的组蛋白乙酰化修饰在提高绿色木霉生物防治中起着重要作用。     

Calcineurin B-like interacting protein kinase 31 confers resistance to sheath blight via modulation of ROS homeostasis in rice

Sheath blight (ShB) severely threatens rice cultivation and production; however, the molecular mechanism of rice defence against ShB remains unclear. Screening of transposon Ds insertion mutants identified that Calcineurin B-like protein-interacting protein kinase 31 (CIPK31) mutants were more susceptible to ShB, while CIPK31 overexpressors (OX) were less susceptible. Sequence analysis indicated two haplotypes of CIPK31: Hap_1, with significantly higher CIPK31 expression, was less sensitive to ShB than the Hap_2 lines. Further analyses showed that the NAF domain of CIPK31 interacted with the EF-hand motif of respiratory burst oxidase homologue (RBOHA) to inhibit RBOHA-induced H₂O₂ production, and RBOHA RNAi plants were more susceptible to ShB. These data suggested that the CIPK31-mediated increase in resistance is not associated with RBOHA. Interestingly, the study also found that CIPK31 interacted with catalase C (CatC); cipk31 mutants accumulated less H₂O₂ while CIPK31 OX accumulated more H₂O₂ compared to the wild-type control. Further analysis showed the interaction of the catalase domain of CatC with the NAF domain of CIPK31 by which CIPK31 inhibits CatC activity to accumulate more H₂O₂.     

RNF7 promotes glioma growth via the PI3K/AKT signalling axis

RNF7 has been reported to play critical roles in various cancers. However, the underlying mechanisms of RNF7 in glioma development remain largely unknown. Herein, the expression level of RNF7 was examined in tissues by quantitative real-time PCR, Western blotting and immunohistochemistry. The effect of RNF7 on glioma progression was measured by performing CCK-8 and apoptosis assays, cell cycle-related experiments and animal experiments. The effect of RNF7 on PI3K/AKT signalling pathway was tested by Western blotting. First, we found that RNF7 was upregulated in tumour tissue compared with normal brain tissue, especially in high-grade glioma, and the high expression of RNF7 was significantly related to tumour size, Karnofsky Performance Scale score and a poor prognosis. Second, RNF7 overexpression facilitated tumour cell cycle progression and cell proliferation and suppressed apoptosis. Conversely, RNF7 knockdown suppressed tumour cell cycle progression and cell proliferation and facilitated apoptosis. Furthermore, follow-up mechanistic studies indicated that RNF7 could facilitate glioma cell proliferation and cell cycle progression and inhibit apoptosis by activating the PI3K/AKT signalling pathway. This study shows that RNF7 can clearly promote glioma cell proliferation by facilitating cell cycle progression and inhibiting apoptosis by activating the PI3K/AKT signalling pathway. Targeting the RNF7/PI3K/AKT axis may provide a new perspective on the prevention or treatment of glioma.     

胶质母细胞瘤外泌体的作用机制研究进展

胶质母细胞瘤(glioblastoma,GBM)因组织学异质性、侵袭能力强、术后复发快等问题,致使患者经手术治疗、化疗和放疗后的预后差,总体生存期短。GBM细胞来源外泌体(GBM cell-derived exosome,GBM-exo)能够通过其携带的细胞因子、miRNA、DNA和蛋白质等调节GBM细胞的增殖和迁移,通过血管生成蛋白和非编码RNA促进肿瘤血管生成,通过调节因子、蛋白质和药物靶向免疫检查点等介导肿瘤免疫逃逸,以及通过非编码RNA对抗GBM细胞的耐药性,有望成为个性化治疗GBM的重要靶标,且可以作为GBM的诊断和预后标志物。本文阐述了GBM-exo的制备方法和生物学特征,及其在GBM细胞增殖、血管生成、免疫逃逸和耐药性方面的作用和分子机制,为研发诊治GBM的新策略提供参考。     

Rhizosphere effect of nanoscale zero-valent iron on mycorrhiza-dependent maize assimilation

Rhizosphere effect of nanoscale zero-valent iron (nZVI) is crucial but little reported. Maize seeds were dressed with four nZVI concentrations (0, 1.0, 1.5, 2 g kg⁻¹) and inoculated with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae). The SEM images illuminated that excessive nZVI particles (2 g kg⁻¹) were agglomerated on the surface of hyphae and spore, causing severe deformation and inactivation of AMF symbionts and thereafter inhibiting water uptake in maize seedlings. This restrained the scavenging effects of enzymatic (superoxide dismutase, peroxidase) and non-enzymatic compounds (proline & malondialdehyde) on ROS, and leaf photoreduction activity and gas exchange ability (p < 0.05). Interestingly, the inoculation with AMF effectively alleviated above negative effects. In contrast, appropriate dose of nZVI, that is, ≤1.5 g kg⁻¹, can be evenly distributed on the hyphae surface and form the ordered symbionts with AMF. This help massively to enhance hyphae growth and water and nutrient uptake. The enhanced mycorrhizal infection turned to promote rhizosphere symbiont activity and leaf Rubisco and Rubisco activase activity. Light compensation point was massively lowered, which increased photosynthetic carbon supply for AMF symbionts. Particularly, such priming effects were evidently enhanced by drought stress. Our findings provided a novel insight into functional role of nZVI in agriculture and AMF-led green production.     

“DNA signaturing” database construction for Tetradesmus species identification and phylogenetic relationships of Scenedesmus-like green microalgae (Scenedesmaceae,Chlorophyta)

Species identification of Scenedesmus-like microalgae, comprising Desmodesmus, Tetradesmus, and Scenedesmus, has been challenging due to their high morphological and genetic similarity. After developing a DNA signaturing tool for Desmodesmus identification, we built a DNA signaturing database for Tetradesmus. The DNA signaturing tool contained species-specific nucleotide sequences of Tetradesmus species or strain groups with high similarity in ITS2 sequences. To construct DNA signaturing, we collected data on ITS2 sequences, aligned the sequences, organized the data by ITS2 sequence homology, and determined signature sequences according to hemi-compensatory base changes (hCBC)/CBC data from previous studies. Four Tetradesmus species and 11 strain groups had DNA signatures. The signature sequence of the genus Tetradesmus, TTA GAG GCT TAA GCA AGG ACCC, recognized 86% (157/183) of the collected Tetradesmus strains. Phylogenetic analysis of Scenedesmus-like species revealed that the Tetradesmus species were monophyletic and closely related to each other based on branch lengths. Desmodesmus was suggested to split into two subgenera due to their genetic and morphological distinction. Scenedesmus must be analyzed along with other genera of the Scenedesmaceae family to determine their genetic relationships. Importantly, DNA signaturing was integrated into a database for identifying Scenedesmus-like species through BLAST.     

Do Geographically Isolated Grasslands Follow the Principle of Island Biogeography in a Landscape Scale? Taking Poyang Lake Grassland as an Example

As one of the basic theories of biodiversity conservation, island biogeography has been widely accepted in the past decades. Originally, island biogeography was put forward and applied in oceanic environments. But later on, it was found out that the application was not only limited to oceanic islands, but also in terrestrial environments with relatively isolated conditions. In terms of biodiversity level, island biogeography generally focuses on a small scale, such as species diversity and genetic diversity. The studies of biodiversity on a large-scale based on island biogeography, such as ecosystem and landscape scales, were seldomly conducted. Taking Poyang Lake, the largest fresh water lake in China as case study area, 30 grasslands were randomly selected to study whether island biogeography can be applied to grasslands at a landscape level from three island attributes (area, distance and shape), and the most important ecological variable (flooding) in Poyang Lake. The results showed that in general, grasslands have the property of an island, and follow the basic principle of island biogeography. We found the area and flooding duration were the two most important determinants of landscape diversity. There was a significant positive correlation between the grassland area and the landscape diversity, which could be well expressed by logarithmic function model (R² = 0.73). There was a negative correlation between flooding duration and landscape diversity, which could be described by an inverse model (R² = 0.206). The distance to mainland and the shape of grassland were correlated with landscape diversity, but the fitting result of the models was not as good as expected. The possible reason could be that Poyang Lake is a seasonal lake, the water level varies with hydrological conditions, so that the grasslands are not strongly isolated and their shape is not stable enough required by island biogeography. Furthermore, it indicates that besides area, distance and shape attributes, flooding strongly affects the biodiversity of grassland vegetation, and should not be ignored when applying island biogeography theory to Poyang Lake. This study is expected to be a supplement for island biogeography in terrestrial environments, and the results are expected to benefit for the biodiversity conservation in Poyang Lake.     

串叶松香草Giemsa C带和染色中心研究

以Giemsa C带技术处理串叶松香草根尖细胞染色体(2n=14),全部着丝点及第5和第7对染色体短臂端部显稳定的C带,第6对染色体长臂有两条明显的居间带,其他居间带小而不稳定(重复率不高)。间期细胞核染色体呈Rable构型,其着丝点一极最多出现20个染色中心。统计分析表明,靠近着丝点的短臂端带区和居间带区异染色质有易与着丝点区异染色质融合的倾向。分裂中期Giemsa C带数目与间期染色中心数目存在数量对应关系。     

New Isopropyl Chromone and Flavanone Glucoside Compounds from the Leaves of Syzygium cerasiforme (Blume) Merr. & L.M.Perry and Their Inhibition of Nitric Oxide Production

A new isopropyl chromone ( 1 ) and a new flavanone glucoside ( 2 ) together with eleven known compounds ( 3–13 ) were isolated from the leaves of Syzygium cerasiforme (Blume) Merr. & L.M.Perry. Their structures were elucidated as 5,7-dihydroxy-2-isopropyl-6,8-dimethyl-4H-chromen-4-one ( 1 ), 5,7-dihydroxyflavanone 7-O-β-D-(6′′-O-galloylglucopyranoside) ( 2 ), strobopinin ( 3 ), demethoxymatteucinol ( 4 ), pinocembrin-7-O-β-D-glucopyranoside ( 5 ), (2S)-hydroxynaringenin-7-O-β-D-glucopyranoside ( 6 ), afzelin ( 7 ), quercetin ( 8 ), kaplanin ( 9 ), endoperoxide G3 ( 10 ), grasshopper ( 11 ), vomifoliol ( 12 ), litseagermacrane ( 13 ) by the analysis of HR-ESI-MS, NMR, and CD spectral data. Compounds 1 , 2 , 5 , 6 and 10 inhibited NO production on LPS-activated RAW264.7 cells with IC₅₀ values of 12.28±1.15, 8.52±1.62, 7.68±0.87, 9.67±0.57, and 6.69±0.34 μM, respectively, while the IC₅₀ values of the other compounds ranging from 33.38±0.78 to 86.51±2.98 μM, compared to that of the positive control, N^G-monomethyl-L-arginine acetate (L-NMMA) with an IC₅₀ value of 32.50±1.00 μM.