Promotive Effect of Low Concentrations of NaHSO3 on Photophosphorylation and Photosynthesis in Phosphoenolpyruvate Carboxylase Transgenic Rice Leaves

Spraying a 1-2 mmol/L solution of NaHSO3 on the leaves of wild-type rice (Oryza sativa L.)Kitaake (WT), phosphoenolpyruvate carboxylase (PEPC) transgenic (PC) rice and PEPC phosphate dikinase(PPDK) transgenic rice (PC PK), in which the germplasm was transformed with wild-type Kitaake as the gene receptor, resulted in an enhancement of the net photosynthetic rate by 23.0%, 28.8%, and 34.4%,respectively, for more than 3 d. It was also observed that NaHSO3 application caused an increase in the ATP content in leaves. Spraying PMS (a cofactor catalysing the photophosphorylation cycle) and NaHSO3 separately or together on leaves resulted in an increase in photosynthesis with all treatments. There was no additional effect on photosynthetic rate when the mixture was applied, suggesting that the mechanism by which NaHSO3 promotes photosynthesis is similar to the mechanism by which PMS acts and that both of compounds enhanced the supply of ATE After spraying a solution of NaHSO3 on leaves, compared with the WT Kitaake rice, a greater enhancement of net photosynthetic rate was observed in PEPC transgenic(PC) and PEPC PPDK transgenic (PC PK) rice, with the greatest increase being observed in the latter group. Therefore ATP supply may become the limiting factor that concentrates CO2 in rice leaves transformed with an exogenous PEPC gene and exogenous PEPC PPDK genes.     

Antiporter Gene from Hordum brevisubulatum （Trin.） Link and Its Overexpression in Transgenic Tobaccos

A vacuolar Na^ /H^ antiporter cDNA gene was successfully isolated fromHordeum brevisubulatum (Trin.) Link using the rapid amplification ofcDNA ends (RACE) method. The gene was named HbNHXI and was found to consist of 1 916 bp encoding a predicted polypeptide of 540 amino acids with a conserved amiloride-binding domain. Phylogenetic tree analysis of the Na^ /H^ antiporters showed that the HbNHXI gene shares 55.3%-74.8% similarity with the vacuolar-type Na^ /H^ antiporters. Transgenic tobaccos that contain the HbNHXI gene, integrated by forward insertion into the tobacco genome, were obtained via Agrobacterium tumerfaciens and characterized for the determination of the concentration of Na^ and K^ ions, as well as proline, in the presence of 300 mmol/L NaCl. The T1 transgenic plants showed more tolerance to salt and drought than did wild-type plants. Our data suggest that overexpression of the HbNHXI gene could improve the tolerance of transgenic tobaccos to salt and drought through the function of the vacuolar Na^ /H^ antiporter.     

Glycosides from Roots of Cyathula officinalis Kuan

Abstract: To search for new and bioactive compounds from traditional Chinese medicines, a new glycoside, 3-O-[α- L -rhamnopyranosyl-(1→3)-( n -butyl-β- D -glucopyranosiduronate)]-28-O-β- D -glucopyranosyloleanolic acid ( 1 ), was isolated from the roots of Cyathula officinalis Kuan, along with 3-O-(methyl-β- D -glucopyranosiduronate)-28-O-β- D -glucopyranosyl oleanolic acid ( 2 ), 3-O-β- D -glucopyranosyl oleanolic acid ( 3 ), 3-O-β- D -glucuronopyranosyl oleanolic acid ( 4 ), 3-O-[β- L -rhamnopyranosyl-(1→3)-(β- D -glucuronopyranosyl)] oleanolic acid ( 5 ), 3-O-(β- D -glucuronopyranosyl)-28-O-β- D -glucopyranosyl oleanolic acid ( 6 ), 28-O-β- D -glucuronopyranosyl-(1→4)-β- D -glucopyranosyl hederagenin ( 7 ), 3-O-[β- L -rhamnopyranosyl-(1→3)-β- D -glucuronopyranosyl]-28-O-β- D -glucopyranosyl oleanolic acid ( 8 ), and 3-O-[β- D -glucopyranosyl-(1→2)-α- L -rhamnopyranosyl-(1→3)-β- D -glucuronopyranosyl]-28-O-β- D -glucopyranosyl oleanolic acid ( 9 ). The structures of these compounds were determined based on spectral and chemical evidence. The 50 per cent growth-inhibiting (GI₅₀) of compounds 1 and 5 against MDA-MB-231 (a human breast cancer cell line) was 3.44 × 10^-4 and 4.66 × 10^-4 mol/L, respectively.
(Managing editor: Wei WANG)     

彩色多普勒超声对原位肝移植术后血流动力学研究

目的:探讨彩色多普勒超声(CDI)在原位肝移植术后对移植肝血流动力学变化的诊断价值。方法:应用CDI连续观察6例原位肝移植患者移植肝脏形态学变化,肝动脉峰值流速(HAmax)、门静脉及肝静脉平均流速(PVmean,HVmean)等指标,并以30例健康成人男性肝脏的血流动力学参数作为正常对照组。结果:在术后2周内肝脏移植组的HAmax低于正常对照组,1周内表现更为明显;术后1周内移植肝脏组的PVmean高于正常对照组,1周后表现不明显;移植肝脏组的Hvmean与正常对照组相比无明显差异。2周后,HA、PV和HV的血流速度基本上趋于正常。结论:CDI技术对了解肝移植术后移植肝的灌注情况,及早发现肝移植术后早期的并发症有重要意义。     

贵州环口螺科一新种记述(前鳃亚纲,中腹足目,环口螺科)

在整理贵州省贵阳地区陆生贝类标本时,经鉴定发现1新种,即奇异阿勇螺Arinia mirifica sp.nov..隶属于前鳃亚纲、中腹足目、环口螺科、阿勇螺属.对新种形态特征、栖息环境进行了记述,并对其近似种也进行了讨 论.     

RNA 沉默的病毒抑制子

RNA 沉默是一种在真核生物体内普遍保守的、通过核酸序列特异性的相互作用来抑制基因表达的调控机制 . RNA 沉默的一种重要生物学效应是防御病毒的侵染,而针对寄主的这种防御机制,许多植物病毒已演化通过编码 RNA 沉默的抑制子来克服这种防御反应 . 目前,已从植物、动物和人类病毒中鉴定了 20 多种 RNA 沉默的抑制子,围绕抑制子的鉴定和作用机理研究已成为病毒学研究的一个热点 . 对 RNA 沉默抑制子的发现、鉴定方法、作用机理及与病毒病症状形成的关系、动物病毒的沉默抑制子等方面的最新进展做了综述,并对沉默抑制子的应用和存在的问题进行了讨论 .     

DNA错配修复蛋白MutS和MutL的相互作用研究

MutL 和 MutS 是DNA错配修复系统中起关键作用的修复蛋白. 利用基因融合技术高效表达了MutL 和 MutS融合蛋白,并利用它们发展了一种研究二者相互作用的简便方法. 融合蛋白MutL-GFP (Trx-His6-GFP-(Ser-Gly)6-MutL),MutL-Strep tagⅡ (Trx-His6-(Ser-Gly)6-Strep tagⅡ-(Ser-Gly)6-MutL) 和 MutS (Trx-His6-(Ser-Gly)6-MutS) 被构建并在大肠杆菌中高效表达. 收集菌体细胞、超声波破碎后离心取上清进行SDS-聚丙烯酰胺凝胶电泳 (SDS-PAGE) 分析,结果表明有与预期分子质量相应的诱导表达条带出现,其表达量约占全细胞蛋白的30％且以可溶形式存在. 利用固定化金属离子配体亲和层析柱分别纯化融合蛋白,其纯度达到90％. 通过将MutS蛋白固定的方法研究两种MutL融合蛋白分别与MutS之间的相互作用. 结果表明：只有MutS蛋白与含有错配碱基DNA分子结合后才与MutL蛋白发生相互作用. 通过检测MutL融合蛋白标记的绿色荧光信号或酶学显色信号来鉴定相互作用的发生. 建立的融合分子系统方法也为研究其他的蛋白质或生物大分子之间的相互作用提供了一个技术平台.     

中国植物区系新资料

在对中国科学院西双版纳热带植物园标本馆植物标本的鉴定清理工作中,发现中国新记录植物2种,兹报道如下,供有关部门和研究者参考。     

利用GUS基因瞬时表达探索佛手叶盘基因枪转化参数

佛手是芳香科枸橼类植物,有很好的药用和观赏价值,但其品种较为单一,对其进行遗传改良和品种选育显得十分必要.为了将基因枪转化方法应用于佛手的遗传改良和品种选育,本实验以GUS基因为报告基因,利用基因枪方法将其转入金华佛手外植体内,通过检测GUS基因在佛手叶盘中的瞬时表达情况,分析了外植体的幼嫩程度、射程、氦气压力、真空度、轰击次数等参数对GUS瞬时表达的影响,并研究了最佳检测时间.结果表明,以幼叶为受体,在射程为6 cm、氦气压力为7.584×106Pa,真空度为88.046 kPa条件下,2 d后可检测出GUS基因的最佳表达活性.轰击次数多少对GUS基因瞬时表达影响不明显.     

细胞衰老与肿瘤发生及药物治疗

肿瘤细胞往往具有衰老障碍而表现出无限增殖的能力。细胞衰老障碍与肿瘤化疗和多药耐药关系密切,恢复肿瘤细胞衰老通路是肿瘤治疗和逆转多药耐药的一个很有前途的研究方向。