濒危药用植物桃儿七的离体培养研究

以桃儿七种子诱导的无菌苗为材料,研究了外源激素对芽诱导、增殖和生根的影响,建立了桃儿七离体培养再生体系。结果表明：芽诱导阶段,采用3.0 mg·L^-1 6-BA+0.5 mg·L^-1 GA₃激素组合,出芽率最高可达85-71%,缩短出芽时间30~40 d,在添加3.0 mg·L^-1 6-BA+0.2 mg·L^-1 IAA的MS培养基上利于增殖,增殖速度快,增殖系数1.63。以WPM+1.5 mg·L^-1 IAA+0.5 mg·L^-1 NAA的培养基培养30 d 后,生根率可达60.1%。     

Methylation protects miRNAs and siRNAs from a 3'-end uridylation activity in Arabidopsis

Small RNAs of 21-25 nucleotides (nt), including small interfering RNAs (siRNAs) and microRNAs (miRNAs), act as guide RNAs to silence target-gene expression in a sequence-specific manner. In addition to a Dicer homolog, DCL1, the biogenesis of miRNAs in Arabidopsis requires another protein, HEN1. miRNAs are reduced in abundance and increased in size in hen1 mutants. We found that HEN1 is a miRNA methyltransferase that adds a methyl group to the 3'-most nucleotide of miRNAs, but the role of miRNA methylation was unknown. Here, we show that siRNAs from sense transgenes, hairpin transgenes, and transposons or repeat sequences, as well as a new class of siRNAs known as trans-acting siRNAs, are also methylated in vivo by HEN1. In addition, we show that the size increase of small RNAs in the hen1-1 mutant is due to the addition of one to five U residues to the 3' ends of the small RNAs. Therefore, a novel uridylation activity targets the 3' ends of unmethylated miRNAs and siRNAs in hen1 mutants. We conclude that 3'-end methylation is a common step in miRNA and siRNA metabolism and likely protects the 3' ends of the small RNAs from the uridylation activity.     

Activation characteristics of transient receptor potential ankyrin 1 and its role in nociception

Transient receptor potential (TRP) ankyrin 1 (TRPA1) is a Ca(2+)-permeant, nonselective cationic channel. It is predominantly expressed in the C afferent sensory nerve fibers of trigeminal and dorsal root ganglion neurons and is highly coexpressed with the nociceptive ion channel transient receptor potential vanilloid 1 (TRPV1). Several physical and chemical stimuli have been shown to activate the channel. In this study, we have used electrophysiological techniques and behavioral models to characterize the properties of TRPA1. Whole cell TRPA1 currents induced by brief application of lower concentrations of N-methyl maleimide (NMM) or allyl isothiocyanate (AITC) can be reversed readily by washout, whereas continuous application of higher concentrations of NMM or AITC completely desensitized the currents. The deactivation and desensitization kinetics differed between NMM and AITC. TRPA1 current amplitude increased with repeated application of lower concentrations of AITC, whereas saturating concentrations of AITC induced tachyphylaxis, which was more pronounced in the presence of extracellular Ca(2+). The outward rectification exhibited by native TRPA1-mediated whole cell and single-channel currents was minimal as compared with other TRP channels. TRPA1 currents were negatively modulated by protons and polyamines, both of which activate the heat-sensitive channel, TRPV1. Interestingly, neither protein kinase C nor protein kinase A activation sensitized AITC-induced currents, but each profoundly sensitized capsaicin-induced currents. Current-clamp experiments revealed that AITC produced a slow and sustained depolarization as compared with capsaicin. TRPA1 is also expressed at the central terminals of nociceptors at the caudal spinal trigeminal nucleus. Activation of TRPA1 in this area increases the frequency and amplitude of miniature excitatory or inhibitory postsynaptic currents. In behavioral studies, intraplantar and intrathecal administration of AITC induced more pronounced and prolonged changes in nociceptive behavior than those induced by capsaicin. In conclusion, the characteristics of TRPA1 we have delineated suggest that it might play a unique role in nociception.     

半干旱黄土高原地区春小麦地膜覆盖研究概述

在黄土高原半干旱地区春小麦上进行的地膜覆盖试验表明,地膜覆盖通过改善耕层土壤生态环境条件,即通过改善水,热状况,活化土壤养分,对提高水分和养分利用效率,实现粮食增产具有重要作用,但近年来在生产实践和科学实验中发现,不合理的长期全生育期地膜覆盖,因在作物生长前期和中期覆膜作物较不覆膜作物生长好,覆膜作物在生长期水分蒸腾损失严重,土壤水分的蒸散（蒸发＋蒸腾）损失远比不覆膜土壤严重,在作物生长后期降水少或没有补充灌溉时,会产生严重的水分肋迫现象,显著抑制小穗分化和灌浆,最终导致收获得指数和产量下降,同时,地膜覆盖的增产作用在一定程度上是以耗竭土壤肥力,特别是在有机物质为代 的,因此,不正确的地膜覆盖（如全生育期的地膜覆盖）,不仅有时起不到显著的增产作用,而且易造成土壤养分,特别是土壤中硝态氮的累积和损失,肥料利用效率降低,土壤生态条件恶化,下降,难以持续高产,因此在确定地膜覆盖范式时,必须要考虑底墒,作物生育期降水,地膜覆盖的阶段性和氮肥的施用等。     

吸附剂及培养基组成对香荚兰细胞悬浮培养产生香兰素的影响

本文报道了培养基的组成及添加吸附剂对香荚兰细胞悬浮培养产生香兰素的影响。结果表明,添加吸附剂活性炭及XAD-2后,香荚兰细胞产生的香兰素含量明显增加,而且活性炭的效果优于XAD-2;香荚兰细胞在全组成的MS培养基中香兰素含量均低于由矿物质盐组成培养基中的含量。可以考虑采用二步培养法来培养香荚兰细胞及产生香兰素。     

Pituitary adenylate cyclase-activating polypeptide promotes differentiation of mouse neural stem cells into astrocytes

We have found that pituitary adenylate cyclase-activating polypeptide (PACAP) employed at the physiological concentrations induces the differentiation of mouse neural stem cells into astrocytes. The differentiation process was not affected by cAMP analogues such as dibutylic cAMP (db-cAMP) or 8Br-cAMP or by the specific competitive inhibitor of protein kinase A, Rp-adenosine-3',5'-cyclic monophosphothioate triethylamine salt (Rp-cAMP). Expression of the PACAP receptor (PAC1) in neural stem cells was detected by both RT-PCR and immunoblot using an affinity-purified antibody. The PACAP selective antagonist, PACAP(6-38), had an inhibitory effect on the PACAP-induced differentiation of neural stem cells into astrocytes. These results indicate that PACAP acts on the PAC1 receptor on the plasma membrane of mouse neural stem cells, with the signal then transmitted intracellularly via a PAC1-coupled G protein, does not involve Gs. This signaling mechanism may thus play a crucial role in the differentiation of neural stem cells into astrocytes.     

Inhibition of mitochondrial complex I improves glucose metabolism independently of AMPK activation

Accumulating evidences showed metformin and berberine, well‐known glucose‐lowering agents, were able to inhibit mitochondrial electron transport chain at complex I. In this study, we aimed to explore the antihyperglycaemic effect of complex I inhibition. Rotenone, amobarbital and gene silence of NDUFA13 were used to inhibit complex I. Intraperitoneal glucose tolerance test and insulin tolerance test were performed in db/db mice. Lactate release and glucose consumption were measured to investigate glucose metabolism in HepG2 hepatocytes and C2C12 myotubes. Glucose output was measured in primary hepatocytes. Compound C and adenoviruses expressing dominant negative AMP‐activated protein kinase (AMPK) α1/2 were exploited to inactivate AMPK pathway. Cellular NAD⁺/NADH ratio was assayed to evaluate energy transforming and redox state. Rotenone ameliorated hyperglycaemia and insulin resistance in db/db mice. It induced glucose consumption and glycolysis and reduced hepatic glucose output. Rotenone also activated AMPK. Furthermore, it remained effective with AMPK inactivation. The enhanced glycolysis and repressed gluconeogenesis correlated with a reduction in cellular NAD⁺/NADH ratio, which resulted from complex I suppression. Amobarbital, another representative complex I inhibitor, stimulated glucose consumption and decreased hepatic glucose output in vitro, too. Similar changes were observed while expression of NDUFA13, a subunit of complex I, was knocked down with gene silencing. These findings reveal mitochondrial complex I emerges as a key drug target for diabetes treatment. Inhibition of complex I improves glucose homoeostasis via non‐AMPK pathway, which may relate to the suppression of the cellular NAD⁺/NADH ratio.     

九节茶的组织培养和快速繁殖

1植物名称 九节茶[Sarcandra glabra（Thunb．）Nakai],又名草珊瑚、肿节风、接骨莲。 2材料类别带节茎段。     

PLZF-RARα融合基因的生物学功能研究

构建了8个PLZF-RARα融合基因突变体.用“滞后”胶实验证实PLZF-RARα与PML-RARα一样,亦能以同二聚体的形式结合到维甲酸反应元件(RARE)上,且PLZF的POZ结构域介导PLZF-RARα同二聚体的形成和稳定.但两者与RARE的结合类型存在差异,在DR5G,PML-RARα的结合强度大于PLZF-RARα;而在DR5T,则是PLZF-RARα强于PML-RARα.进一步工作证实PLZF-RARα能与RXR形成异二聚体,并产生4种复合物.用免疫沉淀法发现PLZF-RARα亦能与PLZF形成异二聚体,而且也是通过POZ结构域介导PLZF-RARα和PLZF异二聚体的形成.同PML-RARα一样,PLZF-RARα对RARE的结合反应亦受维甲酸调控.     

改良三倍体鲫鱼的生物学特性研究

利用鱼类远缘杂交和雌核发育相结合的方法培育出改良四倍体鲫鲤和改良二倍体红鲫,两者交配制备出一种改良三倍体鲫鱼（湘云鲫2号）.对改良三倍体鲫鱼的染色体数目和组型、性腺和垂体结构、外形特征、生长速度等方面进行了系统的研究.结果表明,改良三倍体鲫鱼的染色体数目为3n=150,核型公式为33m＋51sm＋33st＋33t;其精巢和卵巢在繁殖季节不能产生成熟配子,垂体超微结构显示,GTH细胞内的分泌颗粒和分泌小球在繁殖季节没有大量排出,该特征从内分泌的角度证明了它们的不育性;改良三倍体鲫鱼具有体背高、尾柄短和头部小的优良外形特征.与三倍体湘云鲫相比,改良三倍体鲫鱼不但保留了三倍体鱼生长速度快、不育等特点,而且在体形方面表现出明显的改良特征,是一种新型改良三倍体鲫鱼.