Caveolin-1 plays a crucial role in inhibiting neuronal differentiation of neural stem/progenitor cells via VEGF signaling-dependent pathway

In the present study, we aim to elucidate the roles of caveolin-1(Cav-1), a 22 kDa protein in plasma membrane invaginations, in modulating neuronal differentiation of neural progenitor cells (NPCs). In the hippocampal dentate gyrus, we found that Cav-1 knockout mice revealed remarkably higher levels of vascular endothelial growth factor (VEGF) and the more abundant formation of newborn neurons than wild type mice. We then studied the potential mechanisms of Cav-1 in modulating VEGF signaling and neuronal differentiation in isolated cultured NPCs under normoxic and hypoxic conditions. Hypoxic embryonic rat NPCs were exposed to 1% O₂ for 24 h and then switched to 21% O₂ for 1, 3, 7 and 14 days whereas normoxic NPCs were continuously cultured with 21% O₂. Compared with normoxic NPCs, hypoxic NPCs had down-regulated expression of Cav-1 and up-regulated VEGF expression and p44/42MAPK phosphorylation, and enhanced neuronal differentiation. We further studied the roles of Cav-1 in inhibiting neuronal differentiation by using Cav-1 scaffolding domain peptide and Cav-1-specific small interfering RNA. In both normoxic and hypoxic NPCs, Cav-1 peptide markedly down-regulated the expressions of VEGF and flk1, decreased the phosphorylations of p44/42MAPK, Akt and Stat3, and inhibited neuronal differentiation, whereas the knockdown of Cav-1 promoted the expression of VEGF, phosphorylations of p44/42MAPK, Akt and Stat3, and stimulated neuronal differentiation. Moreover, the enhanced phosphorylations of p44/42MAPK, Akt and Stat3, and neuronal differentiation were abolished by co-treatment of VEGF inhibitor V1. These results provide strong evidence to prove that Cav-1 can inhibit neuronal differentiation via down-regulations of VEGF, p44/42MAPK, Akt and Stat3 signaling pathways, and that VEGF signaling is a crucial target of Cav-1. The hypoxia-induced down-regulation of Cav-1 contributes to enhanced neuronal differentiation in NPCs.     

苦瓜冻干粉对动物的降血糖作用及急性毒性

对药食同源植物苦瓜（Ｍｏｍｏｒｄｉｃａ ｃｈａｒａｎｔｉａ Ｌ．）的鲜汁冻干粉对动物的降血糖作用及急性毒性进行了药理实验,苦瓜冻干粉（生药量２０ｇ／ｋｇ和４０ｇ／ｋｇ）对药物性高血糖小鼠具有显著的降血糖作用,同时对正常小鼠血糖没有影响;苦瓜冻干粉的小鼠口服ＬＤ５０为生药量７０４．８ｇ／ｋｇ（９５％可信限生药量６１８．４～８０４ｇ／ｋｇ）,其产生降糖药效的剂量仅为其ＬＤ５０的１／３５～１／１７。     

The role of OsCOM1 in homologous chromosome synapsis and recombination in rice meiosis

COM1/SAE2 is a highly conserved gene from yeast to higher eukaryotes. Its orthologs, known to cooperate with the MRX complex (Mre11/Rad50/Xrs2), are required for meiotic DNA double‐strand break (DSB) ends resection and specific mitotic DSB repair events. Here, the rice (Oryza sativa, 2n = 2x = 24) COM1/SAE2 homolog was identified through positional cloning, termed OsCOM1. Four independent mutants of OsCOM1 were isolated and characterized. In Oscom1 mutants, synaptonemal complex (SC) formation, homologous pairing and recombination were severely inhibited, whereas aberrant non‐homologous chromosome entanglements occurred constantly. Several key meiotic proteins, including ZEP1 and OsMER3, were not loaded normally onto chromosomes in Oscom1 mutants, whereas the localization of OsREC8, PAIR2 and PAIR3 seemed to be normal. Moreover, OsCOM1 was loaded normally onto meiotic chromosomes in Osrec8, zep1 and Osmer3 mutants, but could not be properly loaded in Osam1, pair2 and OsSPO11‐1^RNAi plants. These results provide direct evidence for the functions of OsCOM1 in promoting homologous synapsis and recombination in rice meiosis.     

Heat shock protein 90-mediated inactivation of nuclear factor-κB switches autophagy to apoptosis through becn1 transcriptional inhibition in selenite-induced NB4 cells

Autophagy can protect cells while also contributing to cell damage, but the precise interplay between apoptosis and autophagy and the contribution of autophagy to cell death are still not clear. Previous studies have shown that supranutritional doses of sodium selenite promote apoptosis in human leukemia NB4 cells. Here, we report that selenite treatment triggers opposite patterns of autophagy in the NB4, HL60, and Jurkat leukemia cell lines during apoptosis and provide evidence that the suppressive effect of selenite on autophagy in NB4 cells is due to the decreased expression of the chaperone protein Hsp90 (heat shock protein 90), suggesting a novel regulatory function of Hsp90 in apoptosis and autophagy. Excessive or insufficient expression indicates that Hsp90 protects NB4 cells from selenite-induced apoptosis, and selenite-induced decreases in the expression of Hsp90, especially in NB4 cells, inhibit the activities of the IκB kinase/nuclear factor-κB (IKK/NF-κB) signaling pathway, leading to less nuclear translocation and inactivation of NF-κB and the subsequent weak binding of the becn1 promoter, which facilitates the transition from autophagy to apoptosis. Taken together, our observations provide novel insights into the mechanisms underlying the balance between apoptosis and autophagy, and we also identified Hsp90-NF-κB-Beclin1 as a potential biological pathway for signaling the switch from autophagy to apoptosis in selenite-treated NB4 cells.     

Hi-Meth：特定位点DNA甲基化高通量检测平台

胞嘧啶甲基化是DNA表观遗传修饰的主要类型之一,在维持正常细胞功能和调控基因表达中具有重要作用。重亚硫酸盐测序法(bisulfite sequencing PCR,BSP)是特异性位点DNA甲基化检测的通用方法,能明确目的片段中每一个CpG位点的甲基化状态,但此方法需要大量的单克隆测序,操作过程较繁琐、成本昂贵。因此,开发准确、高效、便捷的DNA甲基化检测技术对提升表观遗传研究效率具有重要意义。基于本课题组开发的高通量突变类型检测平台Hi-TOM (high-throughput tracking of mutations),我们进一步建立了特定位点DNA甲基化高通量检测平台Hi-Meth (high-throughput detection of DNA methylation)。DNA样品通过重亚硫酸盐处理之后,仅需一轮PCR扩增即可通过Hi-Meth平台获得特定位点DNA甲基化分析结果。利用Hi-Meth平台,对水稻不同基因启动子区域进行了DNA甲基化检测分析,并与基于BSP方法获得的结果进行了比较。结果表明,Hi-Meth策略与BSP策略检测结果基本一致。而且通过Hi-Meth平台可以更准确、便捷地获得特异性位点DNA甲基化分析结果。综上所述,Hi-Meth为特定DNA区域提供了重要的甲基化检测平台,对表观遗传研究具有重要意义。     

QTL editing confers opposing yield performance in different rice varieties

Grain yield is one of the most important and complex trait for genetic improvement in crops; it is known to be controlled by a number of genes known as quantitative trait loci(QTLs). In the past decade, many yield-contributing QTLs have been identified in crops.However, it remains unclear whether those QTLs confer the same yield performance in different genetic backgrounds. Here, we performed CRISPR/Cas_9-mediated QTL editing in five widely-cultivated rice varieties and revealed that the same QTL can have diverse, even opposing, effects on grain yield in different genetic backgrounds.     

Salicylic acid-induced antioxidant protection against low temperature in cold-hardy winter wheat

“Dongnongdongmai 1” is a cultivated winter wheat which can endure cold temperature as low as ?30 °C with a reviving rate of 85 %. We aimed to explore the involvement of antioxidant protection system in salicylic acid (SA)-enhanced cold resistance of winter wheat. Seedlings were prayed with 0.1 mM SA at three-leaf stage, followed by cold acclimation at tillering stage (4 °C for 5 days) prior to cold treatment at 4, 0, ?10 or ?20 °C for 2 days. Under low temperature, the relative electrical conductivity (REC) of rhizomes and H₂O₂ content in rhizomes were lower compared with leaves, while in the reactive oxygen species (ROS) removal system, only the POD activity was higher. Foliar spray with SA significantly inhibited the cold-increased REC of rhizomes at ?20 °C and REC of leaves at ?10 and ?20 °C. In addition, application of SA prior to ?10 or ?20 °C treatment suppressed the increase in H₂O₂ content both in rhizomes and leaves. SA enhanced the activities of SOD, POD, and CAT in wheat following low-temperature treatment, especially at ?10 and ?20 °C. In addition, spray with SA resulted in 1.1-to-4.9-fold enhanced activities of the key enzymes in AsA–GSH cycle, including APX, DHAR, and MDHAR. Our results suggested that SA could improve the resistance of winter wheat against extreme low temperature by enhancing the activities of antioxidases to eliminate ROS and maintain the redox homeostasis. In addition, the less damage to rhizomes in comparison with leaves may be attributed to enhanced POD activity.     

薄层培养的应用现状与前景

植物薄层培养(TCL)实验系统是70年代初发展起来的一个新颖精致的实验系统。由于薄层培养具有组织结构简单、对调控因子敏感、培养易成功等优点,目前已经在植物细胞的分裂、分化及植物生长、发育的调控机制与分子机理等方面的研究得到了广泛的应用。本文综述了薄层培养在形态发生、细胞学、分子生物学等研究领域的应用现状与进展,并对当前薄层培养存在的问题作了评述。     

蔗糖对紫色土豆微型薯形成及花青素含量的影响

为深入探讨蔗糖在植物花青素生物合成过程中的调节作用,以紫色土豆为材料,分析不同蔗糖浓度对紫色土豆外植体生长、花青素含量、微型薯形成以及花青素生物合成相关基因表达的影响。结果表明,紫色土豆外植体在蔗糖浓度为15 g/L时生长情况最好,平均长度最长,平均重量最重,但高浓度蔗糖对外植体生长起抑制作用;蔗糖能促进紫色土豆花青素含量的积累及微型薯的形成,随着蔗糖浓度的增加,花青素含量随之增加,紫色土豆花青素含量在蔗糖浓度为120 g/L时最高,为5.11 mg/g FW,是对照组的8.89倍;蔗糖浓度为60 g/L时,微型薯重量最重,为0.34 g,结实率最高,达到22.50%。RT-PCR结果显示,蔗糖能促进St F3’5’H、St UFGT以及St DFR的表达,蔗糖通过调控此类花青素合成相关基因的表达影响紫色土豆花青素含量。