沙芥花粉萌发特性和柱头可授性的研究

 用培养基发芽法研究沙芥花粉萌发特性;用人工异株授粉法和联苯胺—过氧化氢法测定柱头可授期。结果表明：沙芥花粉萌发的最佳培养基是20%蔗糖+0.001%硼酸;花粉能够萌发的温度范围为15～38 ℃,最适萌发温度为25 ℃;从花蕾充分膨大期至开花后16 h花粉活力较强,开花后48 h花粉基本无活力;花粉储藏的适宜条件为低温（4 ℃）,储藏期为7 d。柱头可授期为开花前48 h至开花后96 h,其中开花后24～72 h可授性强。     

蓝叶忍冬开花生物学特性研究

试验选取性状优良的蓝叶忍冬为母本,主要研究蓝叶忍冬开花与结实期间的生物学特性,即对花期的物候观测、花粉活性测定、柱头可授性测定、花粉量测定、花粉胚珠比(P/O)以及花粉萌发率测定等。结果表明:蓝叶忍冬花粉活性及柱头可授性最高可达80%以上;花粉胚珠比率(P/O)与花粉量呈正相关,花粉量越高,其比值越高;蔗糖溶液浓度为150 g/L、硼酸溶液浓度为100 g/L时,其花粉萌发率相对最高。     

君子兰柱头可授性及花粉在柱头上萌发的研究

以大花君子兰为试材,用联苯胺-过氧化氢法测定君子兰柱头的可授性,观察柱头分泌液情况,荧光显微镜观察柱头结构和花粉在柱头上的萌发过程,研究开花时间对柱头可授性的影响。结果表明:柱头可授性能持续8d,开花3~4d可授性强,同一天中10:00—11:00可授性强;可授性强时,柱头分泌层的细胞排列逐渐疏松,细胞间隙逐渐增大,同时乳突与乳突之间间隔增大,并且分泌粘液量较大;授粉1~2h花粉开始在柱头上萌发,2h以后大量萌发,授粉4h后,花粉管伸长。因此,在君子兰开花3~4d的10:00—11:00进行人工授粉效果最好。     

莼菜传粉生物学及杂交技术研究

对莼菜花器官的结构、开花物候期、开花动态、柱头可授性、花粉活力、花粉/胚珠（P/O）、繁育系统、传粉方式及杂交技术进行初步研究。结果表明：莼菜群体花期为5月初～6月初,30 d左右,单朵花期2 d,同一朵花内的雌雄蕊在时间和空间上隔离。莼菜不存在无融合生殖现象,柱头可授期主要在开花第1天,人工授粉（第1天开放的花）结实心皮的比例为27.8 %,高于自然授粉（20.9 %）;花粉活力在自然条件下保持4～5 d。P/O平均为14 947,属专性异交（Obligate xenogamy）型。     

毛茛铁线莲开花结实生物学特性研究

定点观察毛茛铁线莲的开花物候、开花动态、单花的功能形态特征、花粉活性、访花昆虫的种类及频率,利用去雄、套袋、人工授粉对毛莨铁线莲结实生物学特性进行观察与调查.结果表明:(1)毛茛铁线莲10～11月开花,单花花期为14～18 d.(2)在散粉当天,花粉活性及柱头可授性均最高,随开花时间的延长,柱头可授性及花粉活力逐渐降低.(3)自然结实率、自花结实率和异花结实率差异显著,其中异花结实率最高.     

文冠果优良单株开花生物学特性研究

以陕西杨凌地区的文冠果优良单株为研究对象,通过野外实地定位观测,对文冠果的开花物候期、花形态特征、开花动态、可孕花空间分布、花粉活力和柱头可授性等进行了检测研究。结果表明:杨凌地区文冠果优良单株花期为4月上旬至4月中下旬,一般长达15d左右;树冠中上部的花先于下部开放,外围的花先于内膛开放,顶生花序底部的花先开放,侧生花序基本同时开放;文冠果优良单株花粉活力在初花期不高,开花后第5天达到最高;当花瓣基部斑晕由橙黄色变为橙红色时,柱头可授性最强。     

花龄对火棘柱头可授性及花粉活力的影响

以4种火棘属植物为试材,采用联苯胺-过氧化氢法和TTC法对火棘、全缘火棘、细圆齿火棘与细圆齿火棘细叶变种的柱头可授性和花粉活力分别进行了测定,旨在探讨花龄对火棘花粉活力及柱头可授性变化规律。结果表明:火棘雌雄性器官的育性具有同步性,有利于自然授粉结实;所试材料的花粉活力柱头可授性变化趋势一致,开花后1~2d花粉活力均最强,然后逐渐下降,花粉寿命为5~6d;所试材料均在开花后2~3d内柱头分泌粘液较多,可授性最强,可授期为3~4d;人工辅助授粉花粉收集的最佳时期为花后第1~2天,最佳授粉时期为花后第2~3天。     

龙牙百合生殖特性及繁育规律

以万载龙牙百合为试材,研究了柱头可授性、杂交指数OCI、不同授粉方式对龙牙百合结实的影响,并对其授粉后花粉管伸长情况进行了荧光观察。结果表明:龙牙百合柱头可授期为开花前1d至开花第9天,共10d,可授期较长,柱头在开花4~6d可授性最强;花粉生活力在开花第1~3天最强;花粉-胚珠比(P/O)介于3 673~4 670,杂交指数(OCI)为5,繁育系统属于专性异交,存在传粉限制,需要传粉媒介为其传粉;自花授粉能结实,切柱授粉有助于结实。     

杜鹃红山茶花粉活力与柱头可授性研究

以7a生杜鹃红山茶“红露珍”嫁接苗为试材,采用花粉离体培养法和联苯胺-过氧化氢法,研究测定了杜鹃红山茶不同月份的花粉活力和柱头可授性,并对其花期进行了观测.结果表明:杜鹃红山茶仅3月没有花开,8月开花量达到最大为24.2朵/株.12月当天散粉的花粉活力最好,花粉活力可达94.96％,柱头在未开花时,已具有可授性,不同月份柱头可授性持续时间不同,4、12月开花后48 h柱头仍有可授性.     

百香果花不同发育阶段花粉活力、柱头可授性及其对坐果的影响

【目的】探讨百香果花不同发育阶段花粉活力、柱头可授性变化及有效授粉期，为百香果生产及杂交育种提供理论依据。【方法】于百香果花不同发育阶段测定花粉的萌发率、柱头可授性及对花粉、柱头的电镜观察并进行人工授粉，统计坐果率及分析果实特性。【结果】百香果在花前5 h时的花粉就具有一定的活力，随后花粉活力不断升高，开花后3 h达到高峰，9 h后花粉活力仅为10.63%,20 h后为0。柱头可授性与花粉活力呈极显著正相关，相关系数为0.711，表明百香果花为雌雄蕊同熟。花前3 h授粉的坐果率最高，开花时及花后1 h次之，此后随着时间延长不断降低，花后9 h的坐果率为0。扫描电镜观察表明花前后不同时间的花粉在外观上无明显变化，柱头在花后7 h乳突细胞表面皱缩增多，20 h后柱头皱缩明显。说明可通过观察柱头的乳突细胞外观来判断柱头的可授性，而花粉却不能通过外观判断其活性。花粉活力及柱头可授性与坐果率显著相关，但与单果质量、果实横径、果实纵径、可食率等无显著的相关性，表明花粉活力及柱头可授性只影响坐果率，但对果实特性不产生影响。【结论】百香果花粉及柱头属于雌雄蕊同熟，花粉及柱头的活力期均较短，在开花当天均...     

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.     

Effects of radiation from 188Re on smooth muscle cell proliferation

AIM: Although endovascular radiotherapy inhibits neointimal hyperplasia, the exact alterations induced by β-particles irradiation remain to be elucidated. The objective of this study was to investigate the ability and the cellular mechanism of local β^-particles emission from ¹⁸⁸Re to inhibit vascular smooth muscle cells (SMCs). METHODS: The SMCs in vitro were irradiated by ¹⁸⁸Re with single doses of 2.6 Gy-25.8 Gy. The effects of β-particles on SMCs, such as effective irradiate doses, the period of inhibition for SMCs proliferation, the changes of cell proliferation rate and DNA synthesis rate, cell cycle progression and related gene expression, were investigated by cell count, [³H]-TdR incorporation, cell cycle progression analysis, cell viability and immunocytochemistry, respectivecy. RESULTS: β-particles irradiation with dose of 5.2 Gy could inhibit significantly SMCs proliferation. At dose of 20.6 Gy DNA synthesis inhibitory rate was 92%, SMCs proliferation rate was only 3%. Renoval of ¹⁸⁸Re did not abolish the inhibitory effects of β-particles on SMCs proliferation. The expression of P53 was up regulation and PCNA was down regulation after irradiation. CONCLUSION: β-particles from ¹⁸⁸ Re was significantly effective and permanent in inhibiting SMCs proliferation, and inhibitory effect was in dose-dependet manner ED50was 5 Gy, the best dose to inhibit SMCs proliferation was 20 Gy. β-particles irradiation induced SMCs to occur G₀/G₁ arrest, damaged the ability of SMCs reproliferation and led to cell clonogenic death. P53 and PCNA had regulatiory effects on SMCs proliferation after β-particles irradiation.     

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.     

Effect of L-Arg on plasma content of endothelin and expression of c-fos mRNA in the left ventricle of rats with renovascular hypertensive hypertrophy

AIM:To study the effect of L-Arg on plasma content of endothelin (ET) and the expression of proto-oncogene c-fos mRNA in the left ventricle of rats with renovascular hypertensive hypertrophy. METHODS: The level of c-fos mRNA were measured by in situ hybridization. The ET in plasma were measured by radioimmunoassay. RESULTS:After eight weeks of treatment with L-Arg, the expression of c-fos decreased markedly (P＜0.01). The ET content in plasma also decreased significantly by L-Arg(P＜0.01).CONCLUSION: Plasma ET content and the expression of c-fos in the left ventricle of rats with renovascular hypertensive hypertrophy could be decreased by L-Arg administration.     

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.     

Compositional and Functional Properties of Saskatoon Berry and Blueberry

Abstract

Saskatoon berry (Amelanchier alnifolia Nutt., Rosaceae) and blueberry (Vaccinium corymbosum L., Ericaceae) are substantially equivalent in all characteristics that are important to the consumer, including fruit color, shape, size, nutrition, texture, and uses. In addition, both fruits are native to North America and they have practically identical historical uses and known health benefits. Their composition, processing, nutritional value and metabolism, intended uses, and levels of undesirable substances are compared.     

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.     

Cryopreservation of shoot apices of hawthorn in vitro cultures originating from East Asia

The objective of this study was to establish a cryopreservation protocol for hawthorn shoot apices (Crataegus pinnatifida Bge.). Cryopreservation was carried out via encapsulation–dehydration, vitrification, and encapsulation–vitrification on shoot apices excised from in vitro cultures. We began by showing that cold-acclimation enhanced the regrowth of cryopreserved apices from 10.0 to 65.5% in encapsulation–dehydration. We then decided that the encapsulation–dehydration method was an optimal cryopreservation method for hawthorn shoot apices in terms of its high recovery after cryopreservation as well as its ease of use compared with vitrification and encapsulation–vitrification. In encapsulation–dehydration, the protocol leading to optimal regrowth was as follows: after cold-acclimation at 5 °C in the dark for 2 weeks, excised shoot tips were pretreated for 24 h at 25 °C on hormone-free Murashige and Skoog [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissue culture. Physiol. Plant. 15, 473–497] (MS) basal medium with 0.4 mol/L sucrose, then encapsulated and precultured in liquid MS medium with 0.8 mol/L sucrose for 16 h at 25 °C. Precultured beads were dehydrated for 6 h at 25 °C in the dessicator containing 50 g silica gel to a moisture content of 15.3% (fresh-weight basis) before cryostorage for 1 h. In addition, we examined the effect of adding glycerol to both the alginate beads and loading solution to enhance regrowth after cryopreservation in encapsulation–dehydration. In the present study, it was shown that adding 0.5 mol/L glycerol resulted in high regrowth percentages (82.5–90.0%) in four Crataegus species.     

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.