落羽杉根系有机酸与NSC代谢对三峡消落带水位变化的响应

为探究三峡库区消落带水位变化下落羽杉根系有机酸和非结构性碳水化合物(NSC)的响应特征,以适生木本植物落羽杉为对象,在消落带原位环境中设置对照-SS(海拔175 m,试验期间无水淹)、MS(海拔170 m,中度水淹胁迫)和DS(海拔165 m,深度水淹胁迫)3个处理,分别于海拔170 m和165 m退水时采集样品,测定并分析根系有机酸和NSC的变化。结果表明:(1)库区水淹对落羽杉基径无显著影响,仅有DS组明显抑制了高生长,落羽杉生长能较积极地响应库区水淹。(2)库区水淹对落羽杉侧根和总根有机酸的影响一致,侧根有机酸代谢作用优于主根。与SS组相比,MS组根系有机酸含量增高,DS组根系有机酸含量降低,除部分根系酒石酸、苹果酸、柠檬酸变化达到显著水平外,其余有机酸均无显著变化。(3)库区不同强度水淹对落羽杉根系NSC有不同程度的影响。与SS组相比,MS组可溶性糖无显著变化,淀粉、NSC含量显著增加,但总根NSC在水淹前与水淹后无明显差异;形成鲜明对比的是,DS组显著降低了可溶性糖、NSC含量,对淀粉无显著影响,且水淹后总根NSC显著低于水淹前。(4)相关分析表明,主根、总根草酸、苹果酸、柠檬酸及侧根、总根莽草酸分别与淀粉、NSC间表现出显著相关性(P0.05)。研究结果表明,在三峡库区消落带水淹胁迫下,落羽杉根系有机酸与NSC代谢联系紧密。通过维持一定的根系淀粉含量,保持植株正常的有机酸代谢水平,较好地适应三峡库区消落带生境。     

植被恢复过程中芒萁覆盖对侵蚀红壤氮组分的影响

氮素是限制陆地生态系统生产力的重要因子。采用时空代换法,以红壤侵蚀区未治理、恢复12年和30年的马尾松林为研究对象,对比分析了林下芒萁覆盖地与裸地表层土壤之间氮同位素、不同形态氮组分含量以及不同组分氮含量所占比例之间的差异。结果表明:在所有马尾松林中,芒萁覆盖增加了表层土壤的全氮含量,δ~(15)N值则比林下裸地显著降低了33. 8%—83.1%(P0.05)。随着恢复年限增加,林下芒萁覆盖地表层土壤δ~(15)N值显著下降,而林下裸露地δ~(15)N值没有显著变化(P0.05)。不同恢复年限马尾松林的芒萁覆盖地表层土壤微生物生物量氮、可溶性有机氮和铵态氮含量显著高于林下裸地(P 0.05),而硝态氮含量则显著低于林下裸地(P0.05)。随恢复年限增加,表层土壤微生物生物量氮、可溶性有机氮、铵态氮含量均呈增加趋势,而硝态氮含量则呈下降趋势,不同形态氮占全氮比例表现为:微生物生物量氮铵态氮可溶性有机氮硝态氮。相关分析表明土壤δ~(15)N值与硝态氮极显著正相关,与其他氮组分极显著负相关(P0.01)。由此可见,与林下裸地相比,芒萁覆盖在植被恢复过程中有助于提高表层土壤中全氮、微生物生物量氮、可溶性有机氮和铵态氮含量,降低硝态氮的淋溶损失风险,促进土壤氮保持和积累,从而有利于退化红壤生态系统的恢复。     

溶血磷脂酸对离体培养的大鼠胚胎神经干细胞向神经胶质细胞分化的影响

本研究用免疫细胞化学荧光双标技术观察了溶血磷脂酸（lysophosphatidic acid,LPA）对大鼠胚胎神经干细胞（neural stem cells,NSCs）分化为少突胶质细胞（galactocerebroside—positive,Gal-C阳性）和星形胶质细胞（grim fibrillary acidic protein-positive,GFAP阳性）的影响,并且用RT-PCR技术对NSCs可能表达的LPA受体进行分析。结果显示：（1）加入不同浓度（0．010．0μmol／L）LPA,第7天进行检测时,少突胶质细胞数量呈明显的剂量依赖性增加,峰值出现在1．0μmol／LLPA组,少突胶质细胞所占百分比从对照组的8．5％增加到32．6％;（2）星形胶质细胞的分化几乎不受LPA的影响,第7天时各LPA处理组星形胶质细胞百分比与对照组相比均无显著性差异;（3）RT-PCR结果显示,大鼠胚胎NSCs的LPA1和LPA3受体表达明显,而LPA3受体表达很弱。以上结果表明,较低浓度的LPA可能作为细胞外信号,通过LPA1和LPA3受体促进大鼠胚胎NSCs向少突胶质细胞分化和生成,但对星形胶质细胞的分化过程无明显影响。     

代谢工程发展30年

代谢工程学科建立30年以来先后与分子生物学、系统生物学和合成生物学发生深度的交叉融合,并在此基础上获得了飞速发展,极大地促进了生物技术产业的进步和升级.文中首先基于SCI论文发表情况对30年来代谢工程学术研究现状和我国在该领域的地位和影响力进行了分析,随后总结了近10年来系统生物学方法和合成生物学的主要使能技术在代谢工...     

儿童肠道菌群与食物过敏关系的研究进展

食物过敏(food allergy, FA)在儿童中的发生率逐年升高,严重影响其生活质量,已经成为全球面临的公共卫生问题之一。近年来,人们发现FA儿童的肠道菌群组成与健康儿童有显著差异。深入研究发现,肠道菌群可通过调节树突状细胞、辅助性T细胞、调节性T细胞、肥大细胞和粒细胞等免疫细胞维持免疫平衡,也可通过多种方式增强肠道屏障功能,抑制FA的发生。在已有研究基础上,益生菌和益生元在治疗儿童FA方面也得到了一定应用,但目前的应用效果并不明确。本文以婴幼儿FA在全球范围内患者规模日益扩大为背景,综述了肠道菌群影响FA的部分机制,总结了近年部分益生菌和益生元在治疗和预防婴幼儿FA方面的应用,并为肠道菌群在FA发生和发展中的作用机制研究和益生菌及其相关代谢产物在儿童FA治疗和预防中的应用提出了新思路,对促进婴幼儿FA治疗方法和策略的研究有重要意义。     

Taxonomy and phylogeny of Ceriporia (Polyporales,Basidiomycota) with an emphasis of Chinese collections

Ceriporia accommodates a kind of wood-inhabiting polypores producing resupinate basidiocarps and causing a white rot. More than 30 species of this genus have been described; however, only a few species were referred to molecular phylogeny. In this study, a total of 203 specimens of Ceriporia were studied morphologically, and the ITS and/or nLSU regions from 42 samples, representing 18 species, were sequenced for phylogenetic analysis. Based on both morphological and phylogenetic analyses, three new species of Ceriporia, C. bubalinomarginata, C. pseudocystidiata and C. variegata, are described and illustrated. An annotated identification key is provided for all 20 species of this genus thus far known in China. Our phylogeny shows that (1) Ceriporia is not monophyletic, (2) C. spissa and C. viridans as morphologically circumscribed are polyphyletic, (3) C. inflata is retained for both C. inflata and C. jiangxiensis, and (4) presence or absence of hymenial cystidia is not a useful character in delimiting species relationships in Ceriporia.     

FHA2 is a plant-specific ISWI subunit responsible for stamen development and plant fertility

Imitation Switch (ISWI) chromatin remodelers are known to function in diverse multi‐subunit complexes in yeast and animals. However, the constitution and function of ISWI complexes in Arabidopsis thaliana remain unclear. In this study, we identified forkhead‐associated domain 2 (FHA2) as a plant‐specific subunit of an ISWI chromatin‐remodeling complex in Arabidopsis. By in vivo and in vitro analyses, we demonstrated that FHA2 directly binds to RLT1 and RLT2, two redundant subunits of the ISWI complex in Arabidopsis. The stamen filament is shorter in the fha2 and rlt1/2 mutants than in the wild type, whereas their pistil lengths are comparable. The shorter filament, which is due to reduced cell size, results in insufficient pollination and reduced fertility. The rlt1/2 mutant shows an early‐flowering phenotype, whereas the phenotype is not shared by the fha2 mutant. Consistent with the functional specificity of FHA2, our RNA‐seq analysis indicated that the fha2 mutant affects a subset of RLT1/2‐regulated genes that does not include genes involved in the regulation of flowering time. This study demonstrates that FHA2 functions as a previously uncharacterized subunit of the Arabidopsis ISWI complex and is exclusively involved in regulating stamen development and plant fertility.     

Triptolide prevents bone loss via suppressing osteoclastogenesis through inhibiting PI3K-AKT-NFATc1 pathway

Bone loss (osteopenia) is a common complication in human solid tumour. In addition, after surgical treatment of gynaecological tumour, osteoporosis often occurs due to the withdrawal of oestrogen. The major characteristic of osteoporosis is the low bone mass with micro-architectural deteriorated bone tissue. And the main cause is the overactivation of osteoclastogenesis, which is one of the most important therapeutic targets. Inflammation could induce the interaction of RANKL/RANK, which is the promoter of osteoclastogenesis. Triptolide is derived from the traditional Chinese herb lei gong teng, presented multiple biological effects, including anti-cancer, anti-inflammation and immunosuppression. We hypothesized that triptolide could inhibits osteoclastogenesis by suppressing inflammation activation. In this study, we confirmed that triptolide could suppress RANKL-induced osteoclastogenesis in bone marrow mononuclear cells (BMMCs) and RAW264.7 cells and inhibited the osteoclast bone resorption functions. PI3K-AKT-NFATc1 pathway is one of the most important downstream pathways of RANKL-induced osteogenesis. The experiments in vitro indicated that triptolide suppresses the activation of PI3K-AKT-NFATc1 pathway and the target point located at the upstream of AKT because both NFATc1 overexpression and AKT phosphorylation could ameliorate the triptolide suppression effects. The expression of MDM2 was elevated, which demonstrated the MDM-p53-induced cell death might contribute to the osteoclastogenesis suppression. Ovariectomy-induced bone loss and inflammation activation were also found to be ameliorated in the experiments in vivo. In summary, the new effect of anti-cancer drug triptolide was demonstrated to be anti-osteoclastogenesis, and we demonstrated triptolide might be a promising therapy for bone loss caused by tumour.