人胎盘滋养层细胞培养与体外hCG释放的研究

本研究的目的是了解细胞滋养层细胞和合胞体滋养层细胞体外分化和生物学特性。方法:采用酶消化和Percoll密度梯度离心法,对人足月胎盘细胞滋养层细胞进行分离、纯化和体外培养。采用放射免疫法(RIA)检测细胞培养上清液hCG含量的变化。结果:经分离和纯化的细胞滋养层细胞在体外培养中生长良好,通过细胞分裂和融合形成合胞体滋养层细胞,随着合胞体滋养层细胞的生长,细胞培养上清液中hCG含量显著升高。我们认为从胎盘中分离和纯化的细胞滋养层细胞在体外培养中可分化和融合形成合胞体滋养层细胞,体外hCG含量的增加与合胞体滋养层细胞生长有关。     

Combinatorial interplay of promoter elements constitutes the minimal determinants for light and developmental control of gene expression in Arabidopsis.

Higher plants are able to integrate environmental and endogenous signals to regulate gene expression for optimal development. To define the minimal sequence requirement sufficient to integrate light and developmental signals in controlling promoter activity, we carried out a systematic analysis of the roles of four well-conserved 'light-responsive elements (LREs)' common to many nuclear-encoded photosynthetic genes. A gain-of-function assay using basal promoter-reporter fusions in stable transgenic Arabidopsis was employed to demonstrate that pairwise combinations of the LREs, but not the individual elements alone, can confer light-inducible expression to the reporter gene independently of the basal promoter context and the light-triggered morphological changes. The activity of the synthetic promoters with the paired LREs can be modulated at least by the phytochrome system. Further, those synthetic light-regulated promoters confer a photosynthetic cell-specific expression pattern and respond to the chloroplast development state. Our data suggest that distinct combinatorial interactions of LREs can serve as minimal autonomous promoter determinants which integrate light and developmental signals and modulate promoter activity.     

Inoculation of soybean (Glycine max. (L.) Merr.) with genistein-preincubated Bradyrhizobium japonicum or genistein directly applied into soil increases soybean protein and dry matter yield under short season conditions

In short-season soybean production areas, low soil temperature is the major factor limiting plant growth and yield. The decreases in soybean yield at low temperatures are mainly due to nitrogen limitation. Genistein, the most effective plant-to-bacterium signal in the soybean (Glycine max (L.) Merr.) nitrogen fixation symbiosis, was used to pretreat Bradyrhizobium japonicum. We have previously reported that this increased soybean nodulation and nitrogen fixation in growth chamber studies. Two field experiments were conducted on two adjacent sites in 1994 to determine whether the incubation of B. japonicum with genistein, prior to application as an inoculant, or genistein, without B. japonicum, applied onto seeds in the furrow at the time of planting, increased soybean grain yield and protein yield in short season areas. The results of these experiments indicated that genistein-preincubated bradyrhizobia increased the grain yield and protein yield of AC Bravor, the later maturing of the two cultivars tested. Genistein without B. japonicum, applied onto seeds in the furrow at the time of planting also increased both grain and protein yield by stimulation of native soil B. japonicum. Interactions existed between genistein application and soybean cultivars, and indicated that the cultivar with the greatest yield potential responded more to genistein addition.     

Factors affecting production of COS and CS2 in Leucaena and Mimosa species

Carbon disulfide (CS₂) and carbonyl sulfide (COS) are colorless, foul-smelling, volatile sulfur compounds with biocidal properties. Some plants produce CS₂ or COS or both. When used as an intercrop or forecrop, these plants may have agronomic potential in protecting other plants. Most of the factors which affect production of these plant-generated organic sulfides are unknown. We determined the effects of sulfate concentration, plant age, nitrogen fixation, drought stress, root injury (through cutting), and undisturbed growth on COS production in Leucaena retusa or Leucaena leucocephala and the effect of some of these factors on CS₂ production in Mimosa pudica. In addition, we determined if organic sulfides were produced in all Leucaena species. When L. retusa and M. pudica seedlings were grown in a plant nutrient medium with different sulfate concentrations (50 to 450 mg SL^-1), COS or CS₂ from crushed roots generally increased with increasing sulfate concentration. COS production was highest (74 ng mg^-1 dry root) for young L. retusa seedlings and declined to low amounts (<5 ng mg^-1 dry root) for older seedlings. Nitrogen fixation reduced the amounts of COS or CS₂ produced in L. leucocephala and M. pudica. Under conditions of undisturbed growth, root cutting, or drought stress, no COS production was detected in 4-to 8-weeks-old L. retusa plants. COS or CS₂ or both was obtained from crushed roots or shoots of all 13 known Leucaena species.     

Use of the additive main effects and multiplicative interaction model in QTL mapping for adaptation in barley

The additive main effects and multiplicative interaction (AMMI) model has emerged as a powerful analytical tool for genotype x environment studies. The objective of the present study was to assess its value in quantitative trait locus (QTL) mapping. This was done through the analysis of a large two-way table of genotype-by-environment data of barley (Hordeum vulgare L.) grain yields, where the genotypes constituted a genetic population suitable for mapping studies. Grain yield data of 150 doubled haploid lines derived from the Steptoe x Morex cross, and the two parental lines, were taken by the North American Barley Genome Mapping Project (NABGMP) at 16 environments throughout the barley production areas of the USA and Canada. Four regions of the genome were responsible for most of the differential genotypic expression across environments. They accounted for approximately 50% of the genotypic main effect and 30% of the genotype x environment interaction (GE) sums of squares. The magnitude and sign of AMMI scores for genotypes and sites facilitate inferences about specific interactions. The parallel use of classification (cluster analysis of environments) and ordination (principal component analysis of GE matrix) techniques allowed most of the variation present in the genotype x environment matrix to be summarized in just a few dimensions, specifically four QTLs showing differential adaptation to four clusters of environments. Thus, AMMI genotypic scores, when the genotypes constituted a population suitable for QTL mapping, could provide an adequate way of resolving the magnitude and nature of QTL x environment interactions.Ignacio Romagosa was on sabbatical leave from the University of Lleida and the Institut de Recerca i Tecnologia Agroalimentàries, Lleida, Spain, when this study was conducted     

High-titer bicistronic retroviral vectors employing foot-and-mouth disease virus internal ribosome entry site.

Bicistronic retroviral vectors were constructed containing the foot-and-mouth disease virus (FMDV) internal ribosome entry site (IRES) followed by the coding region of beta-galactosidase (beta-gal) or therapeutic genes, with the selectable neomycin phosphotransferase gene under the control of the viral long terminal repeat (LTR) promoter. LNFX, a vector with a multiple cloning site 3' to foot-and-mouth disease virus IRES, was used to construct vectors encoding rat erythropoietin (EP), rat granulocyte colony-stimulating factor (G-CSF), human adenosine deaminase (ADA) and beta-gal. In transduced primary rat vascular smooth muscle cells the cytokines were expressed at high levels, similar to those obtained from vectors employing the viral LTR promoter. LNFZ, a vector encoding beta-gal, had a 10-fold increase in titer over that of LNPoZ, a comparable vector containing the poliovirus (Po) internal ribosome entry site. Primary canine vascular smooth muscle cells infected with LNFZ and LNPoZ expressed similar activities of beta-gal and neomycin phosphotransferase (NPT). Overall, these vectors had titers between 10(6) and 2 x 10(7) c.f.u./ml, indicating that foot-and-mouth disease virus IRES provides high-titer bicistronic vectors with high-level two gene expression.     

生物复苏——大绝灭后生物演化历史的第一幕

生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭（即集群绝灭）事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存－复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移（即从大绝灭转向其后的生物残存与复苏的研究）。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的     

苏云金芽孢杆菌δ-内毒素基因穿梭质粒的构建

在农业生产中长期使用化学农药已对环境和生态平衡造成一定破坏作用,同时有不少害虫也逐渐产生抗药性从而引起某些害虫的大流行,给农业生产带来巨大损失。应用苏云金杆菌杀虫蛋白基因(Bt基因)可构建具有抗虫作用的抗虫工程菌,这样通过拌种或植物叶面喷雾可达到快速、经济、有效的防治虫害的目的。国际上抗虫工程菌研究应用很快,如美国将BI基因转入到一种正常情况下定居在植物组织中的棒杆菌,将这种工程菌拌玉米种子,这样随植物生长该菌在植物体内大量繁殖,当玉米螟在茎和叶取食时,即因食用表达苏云金杆菌毒蛋白的工程菌而死亡。 田颖川等已克隆了苏云金芽孢杆菌内毒素基因CryIA(b)和CryIA(c)。本文将Bt基因CryIA(c)插入到大肠-枯草穿梭载体pBE-2中构建成Bt毒蛋白基因穿梭质粒pAMY,利用电穿孔法转人大肠杆菌DH5a,枯草芽孢杆菌B.subtilis BR151,IA511,野生型蜡状芽孢杆菌B.cereusa-47,短芽孢杆菌B.brevis A-5和枯草芽孢杆菌90-8,获得了具有较高杀虫活性的工程菌克隆。     

融合株SPSC发酵生产酒精的工艺研究 Ⅰ.絮凝速率、发酵过程的最适温度和pH值

酿酒酵母属(S. cereviae)变异株和粟酒裂殖酵母属(S. pombe)变异株进行属间原生质体融合得到融合株SPSC,该融合株比S. cereviae具有强的自身絮凝能力。以葡萄糖浓度150g/L的底物在30～44℃的温度范围内进行摇瓶厌氧发酵,获得最佳温度范围为34～38℃,最高发酵温度为40℃。在有效容积2.35L悬浮床反应器中,在pH值3.0～5.0范围内进行连续发酵,获得最适发酵pH为3.5～4.5。     

复合诱变原生质体选育耐热碱性蛋白酶高产菌

以地衣芽孢杆菌(Bacillus licheniformis)53号为原始菌株,在原生质体形成和再生的最佳条件下制备原生质体,对原生质体进行复合诱变,对大量再生突变株进行筛选,最终获得了高产、稳定、耐热的碱性蛋白酶产生菌53-G38-6,产酶活力由1104U/ml提高到22080U/ml。适宜的发酵条件:培养基(％)胰蛋白胨1,酵母膏0.5,玉米粉5,Na_2HP0_4·12H_20 0.4,KH_2P0_4 0.03,Na_2CO_3 0.1,自然pH。42℃旋转培养44～48h,得到的蛋白酶热稳定性强,60℃处理1h剩余酶活55％。酶反应最适条件:62℃,pH10.0,在pH9～10.5范围内稳定。