活性炭与Vc液对兔眼蓝莓外植体及愈伤组织褐化的影响

分别以兔眼蓝莓茎尖和茎段及已形成的愈伤组织为外植体,接种于改良WPM的培养基,并在此基础上分别设置加入200mg/L浓度的Vc液以及对照试验,两组均按一定含量活性炭梯度配置培养基,对比研究活性炭与Vc液对兔眼蓝莓外植体和愈伤组织形成中褐化的影响。结果表明:当培养基中加入Vc液且活性炭含量为100～200mg/L时,能有效防止外植体褐化发生;当培养基中加入Vc液且活性炭含量为200～500mg/L时,能有效防止愈伤组织褐化发生。研究为克服兔眼蓝莓初代培养时外植体及初代形成的愈伤组织时极易出现的褐化现象提供依据。     

仙客来愈伤诱导抗褐化研究

以仙客来（Cyclamen persicum Mill）法国莫莱尓F2代植株为材料,选取同一植株的叶片,叶柄和块茎做为外植体进行愈伤诱导,选取最佳愈伤诱导培养基,针对愈伤诱导过程中出现的褐化问题,从不同方面入手,寻求最佳的褐化控制培养基和培养条件,解决组织培养中褐化问题。结果表明：最佳愈伤诱导培养基是MS＋6-BA（0.5 mg/L）＋2,4-D（2 mg/L）＋KT（0.2mg/L）＋琼脂（9 g/L）＋蔗糖（30 g/L）;最佳褐化控制培养基是在愈伤诱导培养基中添加Vc（2mg/L）或PVP（0.5 mg/L）;暗培养能一定程度上抑制褐化的发生;活性炭虽能抑制褐化但同时也抑制仙客来愈伤组织的生长。     

陇东海棠初代离体培养中外植体褐化影响因素研究

为了降低陇东海棠离体初代培养中的褐化现象、提高培养成功率,研究了外植体类型、酒精消毒、低温处理、防褐化剂、暗培养时间和6-BA浓度对陇东海棠在组织培养中外植体褐化的影响。结果表明:以带芽茎段为外植体,用0.1%HgCl2灭菌处理12min,接种在MS+6-BA 0.5~1.0mg/L+IBA 0.2mg/L(pH值5.8)添加PVP 0.5~2g/L的培养基中,低温暗处理5d,对防止外植体褐化效果最佳。     

洋兰组培快繁褐变抑制因子探讨

兰科植物在组培快繁时,存在着易褐变死亡的问题.在培养基中添加1～2g/L活性碳,适时切除培养物的褐化部分及时更换新鲜培养基,能有效地抑制褐变死亡的发生.培养基中加入10%椰子水,采用适宜的培养温度,能促进原球茎的生长,减少原球茎增殖过程中的褐变.采用大花蕙兰幼嫩花梗做外植体,在诱导培养基中添加NAA,有利于防止外植体褐化,降低外植体的褐变率.     

梨外植体组培褐变的影响因子及预防措施

以鸭梨、黄金梨、阿巴特梨和杜梨为试材,对梨组培过程中影响外植体褐化的因素及防褐措施进行了研究。结果表明,品种、采样时期以及外植体内酚类物质含量等因素都显著地影响材料褐化率。抗褐剂试验表明,培养基中添加0.2g/L的聚乙烯吡咯烷酮(PVP)或100mg/L抗坏血酸(Vc),或将外植体在200mg/L抗坏血酸水溶液中浸泡30min后接入添加2g/L活性炭的培养基,均能显著抑制鸭梨褐化的发生。低温试验表明,鸭梨外植体经4℃低温处理6h后接种,或接入初期在4℃低温中培养12～24h,褐化程度明显减轻。     

降低苹果梨组培过程中外植体褐化的研究

为克服苹果梨组织培养过程中外植体的褐变现象,提高试验材料的成活率,试验以苹果梨1 a生营养枝嫩梢为试材,通过不同培养基配方、不同药剂处理及水培处理,探讨降低苹果梨外植体褐变的影响因素.结果表明:1/3 MS培养基中的外植体成活率较高;液体培养基较固体培养基对降低外植体的褐变的效果好;水培处理可有效降低外植体的褐变率;生长季节取材,随外植体木质化程度的加深,随水培期的延长,外植体的褐变率呈现先降低后上升的趋势,水培4 d 处理的外植体成活率最高;最佳取材时期为盛花后期,将材料水培6 d,在1/3 MS 6-BA 1.0 mg/L IBA 0.2 mg/L Vc 75 mg/L中获得83.3%的外植体成活率.     

豆瓣绿愈伤组织诱导及再生体系的建立

以豆瓣绿的叶片、叶柄及带芽茎段为试材,筛选最佳外植体类型;使用激素6-BA与IBA,选出适宜诱导愈伤组织与芽增殖的培养基;研究活性炭对瓶苗生根的影响,选出适合的生根培养基。结果表明:带芽茎段是诱导愈伤组织的最佳外植体,褐化率仅为6.7%,而叶片和叶柄褐化严重,二者褐化率均超过60%;最佳诱导愈伤组织培养基为MS+6-BA 2.0mg/L+IBA 0.1mg/L,出愈率100.00%;最佳不定芽增殖培养基为MS+6-BA 0.5mg/L+IBA 0.1mg/L,增殖系数为13.8;最佳生根培养基为1/2MS+IBA 0.2mg/L+活性炭1.00g/L。     

橄榄愈伤组织诱导体系的初步建立

采用橄榄不同部位外植体、抗氧化剂和植物生长调节剂,研究不同消毒剂、消毒时间和浓度以及植物生长调节剂、光照条件对诱导愈伤组织的影响。结果表明,新鲜去外表皮的幼嫩茎段作为外植体最利于愈伤组织诱导和防止褐变。外植体用自来水冲洗30分钟—洗衣粉水清洗5分钟—70%酒精浸泡30秒—0.1%升汞振荡10分钟效果最好。采用MS+2,4-D4.0mg/L+6-BA0.5mg/L+活性炭1g/L培养基,24小时光照培养更有利于抑制外植体褐化和愈伤组织诱导。     

科技文摘

梨外植体组培褐变的影响因子及预防措施 以鸭梨、黄金梨、阿巴特梨和杜梨为试材，对梨组培过程中影响外植体褐化的因素及防褐措施进行了研究。结果表明，品种、采样时期以及外植体内酚类物质含量等因素都显著地影响材料褐化率。抗褐剂试验表明，培养基中添加0．2g／L的聚乙烯吡咯烷酮（PVP）或100mg／L抗坏血酸（Vc），或将外植体在200mg／L抗坏血酸水溶液中浸泡30rain后接入添；gn2g／L活性炭的培养基，均能显著抑制鸭梨褐化的发生。低温试验表明，鸭梨外植体经4℃低温处理6h后接种，或接入初期在4℃低温中培养12～24h，褐化程度明显减轻。     

非洲菊再生体系的建立

以非洲菊幼嫩花托为外植体,以MS为基础培养基,研究了添加6-BA和NAA的培养基对愈伤组织诱导、丛生芽发生和丛生芽生根的影响。结果表明:花托的大小影响到愈伤组织的诱导和褐化,0.8cm的花托愈伤组织的诱导率高且褐化率低;愈伤组织诱导和芽分化的适宜培养基为MS+6-BA 10mg/L+NAA 0.2mg/L,丛生芽增值的适宜培养基为MS+6-BA 1.0mg/L+NAA 0.1mg/L,生根培养基为1/2MS+IAA 0.2mg/L。     

Relationship between renal hypertension and cardiac α1-adrenoceptor autoantibodies in rats

AIM: To examine the autoantibody against α₁-adrenoceptor and its biologic activities during the development of renal hypertension. METHODS: Renal hypertension of rat was achieved by clipped renal artery, the titre of autoantibody to α₁-adrenoceptor was detected using ELISA immunoassay. Furthermore, the biological offects of these autoantibodies on cultured cardiomyocytes were also examined. RESULTS: After two weeks of clipping renal arteries, both the frequency of occurrence and the titre of autoantibodies to cardiac α₁-adrenergic receptor were significantly increased as compared with the control of pre-treatment. The increased autoantibodies lasted for several weeks and then automatically decreased gradually to the pre-clipping level at 12 weeks. The biological effects of these autoantibodies displayed an "agonistic-like" activities on the beating frequency of cultured neonatal cardiomyocytes. CONCLUSION: Autoantibodies against α₁-adrenoceptor may play a role in the elevation of peripheral vascular resistance and in the development of cardiac hypertrophy in rats with renal hypertension.     

Influence of Mineral Nutrients on Strawberry Fruit Quality and Their Accumulation in Plant Organs

Abstract

This review is based partly on complete articles and partly on abstracts. Three of the 60 articles deal with the total uptake of elements in strawberry plant organs in two different strawberry production systems, both considered as optimal concerning amount and balance of elements. The effect on fruit quality may be dramatic if the level of a particular element is outside this range, but there may also be effects initiated by differences within the optimal range of elements. Most articles refer to product oriented quality, but some focus on consumer oriented quality, as discussed by Shewfelt (1999). The discussion here is on a general basis, so one should keep in mind that there are cultivar differences and that specification of nutrition ideally should mirror the needs of a single cultivar, or a group of cultivars with similar requirements. Also, to get a complete understanding of the subject future reviews should embrace a broader access of information including the effect on plant development of individual elements, such as the role of calcium in fruit firmness and its importance in cell wall structure. However, the intention here is to narrow the information to results that suggest a direct connection between nutrient uptake and fruit quality.     

辣椒素积累生理研究的最新进展

辣椒素的积累主要受到遗传、环境、竞争物质、酶的影响.在遗传方面,辣椒的基因型以及决定辣椒素含量的特定基因对辣椒素的积累起着决定作用,环境中的光照、温度、CO2、肥料起辅助作用,竞争物质,如木质素、类黄酮、蛋白质、单宁、生物碱、香豆素等物质与辣椒素的积累相互抑制,辣椒素的合成酶和降解酶同样影响辣椒素的积累.     

Mixed-severity fire regime in a high-elevation forest of Grand Canyon,Arizona, USA

Fire regime characteristics of high-elevation forests on the North Rim of the Grand Canyon, Arizona, were reconstructed from fire scar analysis, remote sensing, tree age, and forest structure measurements, a first attempt at detailed reconstruction of the transition from surface to stand-replacing fire patterns in the Southwest. Tree densities and fire-/non-fire-initiated groups were highly mixed over the landscape, so distinct fire-created stands could not be delineated from satellite imagery or the oldest available aerial photos. Surface fires were common from 1700 to 1879 in the 4,400 ha site, especially on S and W aspects. Fire dates frequently coincided with fire dates measured at study sites at lower elevation, suggesting that pre-1880 fire sizes may have been very large. Large fires, those scarring 25% or more of the sample trees, were relatively infrequent, averaging 31 years between burns. Four of the five major regional fire years occurred in the 1700s, followed by a 94-year gap until 1879. Fires typically occurred in significantly dry years (Palmer Drought Stress Index), with severe drought in major regional fire years. Currently the forest is predominantly spruce-fir, mixed conifer, and aspen. In contrast, dendroecological reconstruction of past forest structure showed that the forest in 1880 was very open, corresponding closely with historical (1910) accounts of severe fires leaving partially denuded landscapes. Age structure and species composition were used to classify sampling points into fire-initiated and non-fire-initiated groups. Tree groups on nearly 60% of the plots were fire-initiated; the oldest such groups appeared to have originated after severe fires in 1782 or 1785. In 1880, all fire-initiated groups were less than 100 years old and nearly 25% of the groups were less than 20 years old. Non-fire-initiated groups were significantly older (oldest 262 years in 1880), dominated by ponderosa pine, Douglas-fir, or white fir, and occurred preferentially on S and W slopes. The mixed-severity fire regime, transitioning from lower-elevation surface fires to mixed surface and stand-replacing fire at higher elevations, appeared not to have been stable over the temporal and spatial scales of this study. Information about historical fire regime and forest structure is valuable for managers but the information is probably less specific and stable for high-elevation forests than for low-elevation ponderosa pine forests.This revised version was published online in May 2005 with corrections to the Cover Date.     

瓜叶绿素降解关键酶基因PPH和PAO cDNA片段的克隆与表达初步分析

 以西双版纳黄瓜和‘华黄5号’黄瓜叶片为试验材料,研究了衰老过程中两种黄瓜叶片叶绿素含量变化及脱镁叶绿素脱镁叶绿酸水解酶基因PPH和脱镁叶绿酸a加氧酶基因PAO的表达。结果表明：随着叶片衰老,叶绿素a和叶绿素b含量显著降低,叶绿素a与叶绿素b的比值在0.5左右,推测叶绿素b的含量可能对黄瓜叶片保绿起到重要作用。荧光定量RT-PCR分析结果显示：PPH和PAO在西双版纳黄瓜叶片生长35 d时表达量最高,分别为5.50和1.86;PPH在‘华黄5号’叶片35 d时表达量最高,为7.14,而PAO在35和45 d表达量都很高,分别为3.90和3.91;PPH和PAO在西双版纳黄瓜叶片中的表达量低于在‘华黄5号’中。     

Effects of simvastatin on PDGF-BB and serum-induced proliferation of vascular smooth muscle cells and on the expression of tumor suppressor gene PTEN

AIM:To observe the effect of simvastatin on the proliferation of vascular smooth muscle cells(VSMCs) induced by serum and growth factor PDGF-BB and the effect of simvastatin on the expression of PTEN,a important regulator of G₁/S cell cycle transition. METHODS:The DNA synthesis was determined by [³H]-TdR incorporation, cell cycle was examined with flow cytometry, the protein level of PTEN was measured by Western blot method. RESULTS: (1)Simvastatin inhibited [³H]-TdR incorporation in a dose dependent manner. (2) Flow cytometric DNA analysis revealed that simvastatin induced significantly enhancement of G₀/G₁ phase and decrease in S phase VSMCs.(3)Simvastatin increased protein level of PTEN and mevalonate, a metabolite of HMG-COA, reversed the effect of simvastatin on PTEN protein expression. CONCLUSION:Simvastatin may inhibit proliferation of VSMCs and retarded cell cycle in G₀/G₁ phase by increasing PTEN expression through inhibiting synthesis of mevalonate.     

微波消解ICP—MS法测定香菇中重金属含量

采用密闭微波消解法消解香菇样品,在优化微波消解条件的基础上,建立微波消解ICP—MS法同时测定千香菇中As、PI）、Cd、Cr、Cu、Zn、Mn、Fe和Mg九种重金属元素的方法,在最佳试验条件下,加标收率为92．0％～104．6％,RSD为2．2％-5．3％。该方法简便、快速、准确：     

Relationships of landscape,prey and agronomic variables to the abundance of generalist predators in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>) fields

A two-year field study investigated the possible effects of grain sorghum (Sorghum bicolor [L.] Moench) and uncultivated areas on the abundance of generalist predators in commercially-managed cotton (Gossypium hirsutum L.) fields in Texas, USA. From 63 to 70 fields were sampled for pests and predators over nine consecutive weeks during early stages of cotton development. Additional data on agronomic practices and landscape composition at three spatial scales were also collected for each field. Stepwise regression analyses were used to determine the relationships of landscape, agronomic and prey variables to the abundance of generalist predators. Because the variables most closely linked to predator levels could vary over time, separate regressions were conducted for three time periods corresponding to stages of grain sorghum growth (half-bloom, hard-dough, maturity) in each year. Significant relationships between predator abundance and agricultural landscape composition appear in both years and in all three time periods, but the specific relationships of landscape variables to cotton predator levels differed between and within years. At maturity in 2001, predator levels rose as the amount of uncultivated land from 1.6 to 3.2 km distant and the perimeter shared with grain sorghum increased. During 2002, the area of grain sorghum (half-bloom) and uncultivated land (hard-dough) within 1.6 km of cotton fields were both positively related to predator numbers. Cotton planting dates and the abundance of cotton fleahoppers (Pseudatomoscelis seriatus [Reuter]) were also strongly linked to predator numbers during both years. Results suggest that the total amount of grain sorghum or uncultivated land in an area is more important than the presence of these habitats adjacent to cotton fields, and that landscape composition may sometimes be the most important factor in determining predator abundance.     

Inferring the effects of landscape structure on roe deer (Capreolus capreolus) movements using a step selection function

In this study, we sought to understand how landscape structure affects roe deer movements within their home-range in a heterogeneous and fragmented agricultural system of south-western France. We analysed the movements of 20 roe deer fitted with GPS collars which recorded their locations every 2–6 h over several months (mean = 9 months). Based on empirical observations and previous studies of roe deer habitat use, we hypothesised that roe deer should avoid buildings and roads, move preferentially along valley bottoms and through the more wooded areas of the landscape. To test these hypotheses we paired each observed movement step with 10 random ones. Using conditional logistic regression, we modelled a step selection function, which represents the probability of selecting a given step as a function of these landscape variables. The selected model indicated that movements were influenced by all the tested landscape features, but not always in the predicted direction: our results suggested that roe deer tend to avoid buildings, roads, valley bottoms and possibly the more wooded areas (although the latter result should be interpreted with caution, as it may be influenced by a bias in the rate of GPS fix acquisition in woods). The distances to buildings and to roads were the most influential variables in the model, suggesting that the avoidance of potential sources of disturbance may be a key factor in determining ranging behaviour of roe deer in human dominated landscapes.     

Inoculation of growing media with the rhizobacterium Variovorax paradoxus 5C-2 reduces unwanted stress responses in hardy ornamental species

Inoculation of growing media with plant growth promoting rhizobacteria (PGPR) has a number of potential benefits for the production of ornamental plants. Certain rhizobacteria synthesise the enzyme ACC deaminase, which cleaves ACC, the precursor of the plant hormone ethylene. Bacterial metabolism is now known to lead to a reduction in [ACC] in the plant transpiration stream and bacteria are hypothesised to act on ACC exuded from roots. This in turn reduces the ethylene generated in plants growing in growing media inoculated with these bacteria. Here we tested if applications of the ACC deaminase containing rhizobacteria Variovorax paradoxus⁵C–²could be of benefit to ornamental growers by reducing ethylene generation in stressed plants. Ethylene is produced at levels that are inhibitory to growth and development under a number of abiotic stresses. The propagation and production of hardy ornamentals is deleteriously affected by abiotic stresses that involve ethylene signalling, including drought and physical wounding. Inoculation of growing media with V. paradoxus 5C-2 lowered ethylene emission from mature leaves of Cytisus × praecox experiencing drought stress. In addition, bacterial inoculation of the growing media resulted in significantly reduced abscission of the mature leaves under drought treatment. Beneficial effects of inoculation where also found in the wounding response of Fargesia murielae following divisional propagation and late season senescence in Aquilegia × hybrida in response to drought stress. Together these results demonstrate that V. paradoxus⁵C–²has real potential for use on ornamental nurseries in situations where plant stresses are unavoidable.