牛蒡子醇提物抑制小鼠宫颈癌U14生长的研究

通过建立小鼠宫颈癌U14实体瘤与腹水瘤2种动物模型,观察牛蒡子醇提物对实体瘤抑瘤率和腹水瘤生命延长率的影响。结果发现,以阴性对照组为基础,牛蒡子醇提物3个剂量组及环磷酰胺(CTX)阳性对照组实体瘤各组抑瘤率分别为31.7%、49.7%、57.4%和83.6%(P<0.01);腹水瘤各组生命延长率分别为39.8%、46.6%、62.5%和91.6%(P<0.01)。表明牛蒡子醇提物对小鼠宫颈癌U14的生长有一定的抑制作用。     

赣油14号不同播期的产量比较

通过不同播期试验,研究赣油14号播期与群体产量结构的关系。结果表明:在江西宜春,赣油14号的最佳播期为10月6日,适宜播期为9月29日~10月13日,产量可达1 792.5~1 929.8 kg/hm2;随着播期的推迟,产量表现为先增后减,变异系数为10.2;在产量结构3因子中,单株有效角果数对产量影响最大,变异系数达13.7;其次是千粒重,变异系数为4.45%;每角粒数对产量影响最小,变异系数为1.42。     

垄距和垄高对甘薯龙薯14号产量和机械收获性状的影响

[目的]研究甘薯龙薯14号机械化收获配套高产栽培技术,为其推广应用提供技术支持。[方法]采用两因素裂区试验方法,探讨不同垄距、垄高对甘薯薯块收获性状、产量的影响。[结果]不同垄距、垄高都对甘薯产量、收获性状有显著的影响。提高垄高可增加单株结薯数和大中薯重比例,降低明薯率、伤薯率,单株薯重和产量先提高后降低;单株结薯数、单株薯重、大中薯重比例、产量、明薯率、伤薯率随垄距的减小而提高。[结论]垄距80 cm、垄高30 cm处理的产量最高,为42.91 t/hm~2,其结薯数和大中薯比例也较高,明薯率为96.40%,较适合小型收获机收获。     

过量表达Fa14-3-3C促进拟南芥对低氮胁迫耐受性的研究

氮元素是植物生长发育过程必不可少的营养元素之一,对禾本科作物生长的影响更加明显。本研究采用RACE技术从高羊茅叶片中克隆获得Fa14-3-3C基因全长,并对其亚细胞定位与分子功能进行系统研究。在烟草表皮细胞中观察发现Fa14-3-3C-GFP主要定位在细胞质中与细胞膜上。将Fa14-3-3C基因在拟南芥中过量表达获得3个单拷贝转基因株系(抗性分离比为3∶1)。在低氮胁迫反应中,Fa14-3-3C过量表达株系OE-1与OE-3的根鲜重显著比野生型高,而OE-2与野生型差异不显著,通过荧光定量PCR分析发现OE-1与OE-3过量表达明显而OE-2没有过量表达,说明Fa14-3-3C对植物耐低氮胁迫调节具有剂量效应。定量观察植物根系生长发现在低氮处理早期OE-1转基因株系就显著优于野生型,主要是通过补偿根系生长的方式缓解低氮胁迫对植物的伤害。因此本研究不仅获得了耐低氮胁迫候选基因,而且验证了其在模式植物中的分子功能,为进一步通过基因工程等手段培育耐低氮胁迫种质资源奠定基础,具有重要理论研究价值与生产应用前景。     

14-3-3蛋白结构与功能预测及其在木薯成熟期的表达分析

为了深入研究木薯14-3-3蛋白结构和功能,也为研究木薯块根淀粉积累的分子调控提供新思路。本研究采用生物信息学方法对木薯14-3-3蛋白家族的组成成分与理化性质、系统发育进化、导肽、亚细胞定位、二级结构、功能结构域、三级结构及亲水性、疏水性进行分析和预测,并对14-3-3基因在不同木薯品种中进行差异表达分析。结果表明：（1）木薯14-3-3蛋白家族16个异构体存在多个不同的保守结构域,二级结构相似的亲水性蛋白家族成员在进化关系上可划分为2大不同的类别;（2）14-3-3基因家族16个成员在花叶木薯、ZM-Seaside和华南9号(SC9)块根成熟期的表达水平存在显著性差异(P<0.05),与花叶木薯和SC9相比,产量较高的木薯品系ZM-Seaside块根中14-3-3基因表达水平显著下降(P<0.05),推测14-3-3蛋白在木薯块根成熟期的淀粉积累过程中可能起着负调控作用。     

利用~(14)C研究檫树苗根系分泌物

檫树苗进行 14 CO2 喂饲后 ,培养于不同培养液中 ,同时动态测定苗木体内光合产物分配和根系分泌物数量 ,并对分泌物进行分离 .结果表明 :在标记后 1 5d内营养液和蒸馏水 2种培养处理苗木叶子中光合产物含量比例分别从 67.42 %下降至 35.0 8%和 34.50 %,而新梢和根中光合物比例分别上升了 1 0 .87%、1 4.5%和 1 7.60 %、 1 2 .68%.檫树苗根系分泌物分泌高峰出现在标记结束后第 3～ 5天 ,以后逐渐减少 ,动态测定的 1 0 d中蒸馏水培养处理分泌累积量一直大于营养液处理的量 ,它们 1 0 d中总共分泌量分别是 50 51 3和 45586dpm·株-1.从分泌物分离来看 ,2种处理檫树苗分泌物中都是糖类占优势 ,分别达到了 60 .0 3%(营养液培养 )和 59.70 %(蒸馏水培养 ) ,其次是有机酸 ,氨基酸占的比例最低 ,2种处理分别仅为 1 8.37%和 1 9.87%     

株型对棉株14C同化物生产及运转分配的影响

运用 14 C示踪技术 ,研究了简化整枝与早打主茎顶心、少留果枝改变株型对 14 C同化物生产分配的影响。结果表明 ,简化整枝蕾期、花铃期果枝叶的光合作用强度和14 C同化量均低于对照 ,且　14 C同化物向主茎和果枝的分配比例也较对照降低。简化整枝早打主茎顶心 ,可提高花铃期果枝叶、叶枝叶的光合作用强度和 14 C同化物向叶枝的分配比例。反映到产量和产量构成因素上 ,表现为简化整枝主茎结铃减少 ,叶枝结铃可弥补其损失 ,单铃重和衣分略有降低 ;简化整枝早打主茎顶心增加了叶枝结铃数 ,且单铃重和衣分略有提高。但处理间的皮棉产量均无显著差异     

Carbon mineralization and microbial activity in a field site trial used for 14C turnover experiments over a period of 30 years

 Long-term experiments on different crop management systems provide essential information about turnover of soil organic matter and changes in microbial properties over a period of time. A long-term field site trial, which was established in 1967 near Vienna, Austria, to document the fate of ¹⁴C-labelled manure (straw and farmyard) under different crop management systems (crop rotation, spring wheat and bare fallow), was investigated. Soil samples were taken in 1997 and separated into size fractions (>250 μm, 250–63 μm, 63–2 μm, 2–0.1 μm and <0.1 μm) after aggregate dispersion using low-energy sonication. Organic C, total N and ¹⁴C content were measured in the bulk soil and the size fractions and microbial properties were analysed in the bulk soil. Additionally, C mineralization in bulk soil samples was monitored at 20 °C over a period of 28 days, and subsequently ¹⁴C-CO₂ content was analysed. The distribution of organic C and N within the size fractions was similar between crop rotation and spring wheat; the highest amounts of organic C and N were found in the clay-sized fraction. The amounts of C and N were significantly smaller in the bare fallow, which was depleted of organic matter in the coarse-sized fractions. ¹⁴C distribution differed significantly from unlabelled C distribution, labelled C was accumulated in the silt-sized fraction, indicating weak humification of the applied manure C. The highest rate of C mineralization was measured in the crop rotation and spring wheat, whereas the emission rate of the bare fallow was about 40% lower. The higher ¹⁴C:C ratio of the bulk soil in comparison to the emitted CO₂ indicated that labelled C compounds still remained mineralizable after a period of 30 years. Microbial properties showed a great difference between crop management systems and bare fallow, particularly regarding urease and xylanase activity. Received: 31 May 1999     

Towards a better understanding of carbon flow in the rhizosphere: a time-dependent approach using carbon-14

 Controversies exist in interpreting rhizosphere C flow obtained by different ¹⁴CO₂ labelling methods. However, there is a need for the standardisation of methods in order to be able to compare values obtained for different plants, different stages of development and different habitats. Perennial bromegrass (Bromus erectus Huds) grown in soils of different fertility was exposed to a ¹⁴CO₂ atmosphere for different periods of time: 1 h, 298 h and 78 days. The evolution of ¹⁴CO₂ in the soil was measured during and after labelling. The ¹⁴C contents of plant and rhizosphere compartments were then estimated. The time-sequence of the rate of ¹⁴CO₂ evolution after 1 h of labelling, indicated a maximum after around 20 h, followed by an exponential decrease. When expressed as a percentage of net ¹⁴C assimilation, root-soil respiration accounted for 14% and 18% in the nutrient-poor and nutrient-rich soils, respectively. Integration of the hourly values over several days showed that the dynamics of the evolution rate were similar for the 298-h and 78-day experiments, thus indicating that rhizosphere C flow was dominated by newly assimilated C. This was confirmed by the proportions of below-ground ¹⁴C, measured for roots, respiration and soil, which were not significantly affected by the labelling regime. The differences were, however, found to be significant between the two types of soils. The conclusion was that the conditions for plant growth during labelling were more important than the length of time of labelling, and that this explained the discrepancies in the literature-cited values. A succession of short-term ¹⁴C labelling of plants at different development stages followed by an allocation period of about 1 week is proposed to give a reliable estimation of the dynamics of C flow in the rhizosphere. Received: 7 June 1999