大鼠早期三级卵泡中的卵母细胞能在联合培养系统中成批适当成熟

我们建立了由离体同步未分化颗粒细胞、动情前期垂体前叶和Δ-4雄烯二酮组成的“联合培养系统”。该联合培养系统可模拟正常生理状态下各相关细胞间的协同作用,更有效地诱发经DES 刺激后所获得的大量大鼠早期三级卵泡中的卵母细胞同步达到适当成熟,从而获得符合正常生理标准的成熟卵球,使卵巢内大量卵母细胞得到充分利用。我们的实验表明,经DES刺激,每侧幼龄大鼠卵巢中平均可取得处在早期三级卵泡中的189枚卵母细胞。在联合培养系统中培养,78%的卵母细胞排出第一极体达到成熟。这些成熟的卵母细胞中88%可正常受精,93%卵裂,经体外培养96h, 有59%的受精卵可发育到桑椹或囊胚。2-细胞期胚胎移植后可发育为健康个体。因此,该联合培养系统为研究大鼠卵母细胞成熟、受精和早胚发育的分子机制提供了非常有效的实验模型。     

野生苦刺花食用价值研究

对苦刺花的基本营养成分进行了较为全面的分析测定.结果表明:苦刺花粗蛋白含量为20.79%,氨基酸种类齐全,并含有VB1、VB2、VPP、VC及胡萝卜素等多种维生素,矿质元素含量丰富,还含有适量的纤维素、碳水化合物、酸及果胶等营养成分;重金属、硝酸盐、亚硝酸盐含量均未超过国家标准.因此,苦刺花营养成分种类齐全,含量丰富,具有较高的营养价值.     

甘薯愈伤组织对干旱胁迫和盐胁迫的生理反应对比

研究干旱胁迫和盐胁迫对“芦选一号”。日‘薯愈伤组织可溶性蛋白、可溶性糖、脯氨酸含量、SOD活性等的影响,从而在细胞水平上探讨甘薯抵御渗透胁迫的生理机制。并分析甘薯细胞对干旱处理（PEG-6000）和盐处理（NaCl）的反应差异。结果表明,可溶性蛋白质含量在干旱胁迫下缓慢升高,在轻度和中度盐胁迫的生长前期和中期有较大幅度的上升。但后期下降,表明短时间盐胁迫下,Na^＋可能促进可溶性蛋白的合成;MDA在重度干旱胁迫下的含量显著低于重度盐胁迫,而SOD活性显著高于盐胁迫。表明在盐胁迫下细胞膜透性增加的主要原网是膜脂过氧化作用。干旱处理则是PEG-6000脱水的直接结果;重度干旱胁迫下,可溶性糖含量在短期内迅速升高,然后下降,而脯氨酸含量则在胁迫中后期迅速上升。脯氨酸可能有补偿可溶性糖含量降低的作用。     

Molecular cloning, expression, and enzymatic activity of a novel endogenous cellulase from the mulberry longicorn beetle, Apriona germari

A novel endogenous beta-1,4-endoglucanase (Ag-EGase III) gene belonging to the glycoside hydrolase family (GHF) 5 was cloned from the mulberry longicorn beetle, Apriona germari. The Ag-EGase III gene spans 1061 bp and consists of a single exon coding for 325 amino acid residues. The Ag-EGase III showed 89% protein sequence identity to another beetle, Psacothea hilaris, cellulase belonging to GHF 5. The Ag-EGase III has the potential proton donor and nucleophile amino acids conserved in GHF 5 and two putative N-glycosylation sites. Northern blot and Western blot analyses showed that Ag-EGases were expressed in the gut; Ag-EGase III and Ag-EGase I were expressed in three gut regions, and no Ag-EGase II was found in hindgut, indicating that the foregut and midgut are the prime sites for cellulase synthesis in A. germari larvae. The cDNA encoding Ag-EGase III was expressed as a 47-kDa polypeptide in baculovirus-infected insect Sf9 cells and the enzyme activity of the purified recombinant Ag-EGase III was approximately 1037 U per mg of recombinant Ag-EGase III. The enzymatic property of the purified recombinant Ag-EGase III showed the highest activity at 55 degrees C and pH 6.0, and was stable at 60 degrees C at least for 10 min. In addition, the N-glycosylation of Ag-EGase III was revealed by treatment with tunicamycin of recombinant virus-infected insect Sf9 cells and with endoglycosidase F of purified recombinant Ag-EGase III, demonstrating that the carbohydrate moieties are not necessary for enzyme activity.     

Synthesis of 1-O-monoacyl or 12-O-monoacyl, 1-,12-O-diacyl-, and 11,12-dehydrated excisanin A 7,14-acetonides and their cytotoxic activity

1-O-Monoacyl, 12-O-monoacyl, 1-,12-O-diacyl, and 11,12-dehydrated excisanin A 7,14-acetonides were synthesized from excisanin A isolated from Rabdosia excisa. The structure and cytotoxic activity relationships (SAR) of the natural parent ent-kaurene diterpenes and these semisynthetic analogues were studied by using P388 murine leukemia cells.     

Hapten synthesis for enzyme-linked immunoassay of the insecticide triazophos

Two haptens of the insecticide triazophos (O,O-diethyl O-[1-phenyl-1H-1,2,4-triazol-3-yl] phosphorothioate) were synthesized by introducing appropriate spacers in the O-ethyl site of the analyte molecular structure. First, thiophosphoryl chloride (PSCl(3)) reacts with methanol at low temperature to give O-ethyl dichlorothiophosphate. After reacting with 1-phenyl-3H-1,2,4-triazol, the O-ethyl dichlorothiophosphate was transformed into the intermediate O-ethyl O-(1-phenyl-1H-1,2,4-triazol-3-yl) chlorothiophosphate. Then the intermediate reacts with 4-aminobutyric acid and 6-aminobutyric acid to produce hapten I and hapten II, respectively. The molecule structures of the two haptens were identified by (1)H nuclear magnetic resonance spectrum and mass spectrum. An enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibody was also developed to evaluate the two haptens. Results showed that the monoclonal antibodies with high titers were obtained after immunizing with protein conjugates of these haptens and that the immunoassay has high affinity and specificity to triazophos. These results suggested that the haptens were synthesized successfully and could be used for immunoassay for the rapid screening and sensitive determination of this insecticide.     

Seasonal Variation of Virioplankton in a Eutrophic Shallow Lake

Lake Donghu is a typical eutrophic freshwater lake in which high abundance of planktonic viruses was recently revealed. In this study, seasonal variation of planktonic viruses were observed at three different trophic sites, hypertrophic, eutrophic, and mesotrophic regions, and the correlation between their abundances and other aquatic environmental components, such as bacterioplankton, chlorophyll a, burst size, pH, dissolved oxygen, and temperature, was analyzed for the period of an year. Virioplankton abundance detected by transmission electron microscope (TEM) ranged from 5.48 × 10⁸ to 2.04 × 10⁹ ml⁻¹ in all the sites throughout the study, and the high abundances and seasonal variations of planktonic viruses were related to the trophic status at the sampled sites in Lake Donghu. Their annual mean abundances were, the highest at the hypertrophic site (1.23×10⁹ ml⁻¹), medium at the eutrophic site (1.19×10⁹ ml⁻¹), and the lowest at the mesotrophic site (1.02×10⁹ ml⁻¹). The VBR (virus-to-bacteria ratio) values were high, ranging from 49 to 56 on average at the three sampled sites. The data suggested that the high viral abundance and high VBR values might be associated with high density of phytoplankton including algae and cyanobacteria in this eutrophic shallow lake, and that planktonic viruses are important members of freshwater ecosystems.     

腐生型眼虫Astasia longa两种TIM同工酶cDNA的克隆和分析

利用 3′ RACE和 5′ RACE技术 ,从腐生型眼虫长变胞藻 (Astasialonga)克隆了磷酸丙糖异构酶(TIM)的两个同工酶cDNA全序列。分析表明 :它们分别编码定位于细胞质的胞质型TIM (cTIM)和定位于质体的质体型TIM (pTIM) ;后者的N端具有引导该酶定位到质体中去的典型“前导序列”。根据这些事实我们推测腐生型眼虫A .longa质体中可能存在功能性的TIM ,并进一步认为该质体可能不只是一般意义上的“叶绿体退化的残迹” ,而仍是一种至少有TIM参与其代谢活动的功能性细胞器