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摘要银杏(Ginkgo biloha L)种子中UDPG pplASE最适温度为29-30℃，最适pH为7．5-8．0，二价阳离子中zn2 、Ba2 对其活性影响较小，Mn2、Mg2 对其有明显影响，而Cu2 、Pb2 有强烈的抑制作用。银杏种子幼小至膨大期，UDPG PPLlase活性较低；种子成熟期至贮藏初期，活性迅速而显著地增强；贮藏过程中活性保持较高水平. 相似文献
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银杏种子中ＵＤＰＧ ＰＰｌａｓｅ最适温度为２９－３０℃，最适ｐＨ为７．５－８．０，二价阳离子中Ｚｎ＾２＋，Ｂａ＾２＋对其活性影响较小，Ｍｎ＾２＋，Ｍｇ＾２＋，ＣＡ＾２＋对其明显影响，而Ｃｕ＾２＋，Ｐｂ＾２＋有强烈的抑制作用。银杏种子幼小至膨大期，ＵＤＰＧ ＰＰｌａｓｅ活性较低，种子成熟至贮藏初期，活性迅速而显著地增强，贮藏过程中活性保持较高水平。 相似文献
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以不同贮藏年限的沙葱种子为试材,采用不同浓度的稀土、氯化镧、氯化钇和氯化铈对贮藏2年和5年的沙葱种子进行浸种处理,测定其活力指标、抗氧化酶活性、超氧阴离子(O2·-)、丙二醛(MDA)和维生素C含量,明确不同处理对沙葱种子萌发及生理生化特性的影响,以期为提高种子利用率和保护种质资源提供参考依据.结果表明:不同浓度的药剂处理对沙葱种子的萌发效果不同,低浓度处理能够促进种子的萌发,其中400 mg·L-1氯化铈处理对沙葱种子萌发效果最好.20℃贮藏温度条件下,沙葱种子抗氧化酶活性最高,50℃贮藏温度条件下,氯化铈处理O2·-产生速率和MDA含量与CK相比,显著下降.维生素C含量在35℃和50℃条件下铈离子高于对照. 相似文献
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紫荆花粉生活力测定及贮藏方法研究 总被引：1，自引：0，他引：1
以紫荆花粉为试材,利用离体培养法、碘-碘化钾染色法(I2-KI)、醋酸洋红染色法和氯化三苯基四氮唑(TTC)染色法对花粉生活力进行测定,并研究了不同贮藏条件对花粉萌发的影响,以期了解紫荆花粉的萌发特性及适宜的贮藏方法。结果表明:培养基中添加不同浓度的蔗糖和硼酸对花粉的萌发有促进作用,紫荆花粉萌发的最适培养基为15%蔗糖+0.004%硼酸+0.08%的琼脂,萌发率达88.46%;I2-KI染色法和TTC染色法不适用于测定紫荆花粉生活力;而醋酸洋红染色法可以作为测定紫荆花粉生活力的方法;花粉生活力随贮藏时间的延长而下降,最佳贮藏方法为4℃干燥,耐贮藏力超过26d。 相似文献
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以苹果梨和新高梨为试材,测定了梨贮藏过程中果胶分解酶的活性变化.结果表明:2品种果实在软化过程中多聚半乳糖醛酸酶(PG)活性均增加且在贮藏后期新高梨的PG活性极显著(p<0.01)高于苹果梨;贮藏性强的苹果梨的β-半乳糖苷酶(β-Gal)活性很低且在贮藏中减少,但贮藏性相对较弱的新高梨的β-Gal活性极显著(p<0.01)高于苹果梨且在可溶性果胶增加的时期达活性高峰;苹果梨的果胶甲基酯酶(PME)活性在贮藏后期有所增加,但新高梨减少.可见,在贮藏过程中PG和β-Gal酶均是梨果实软化的重要酶,但β-Gal的作用比PG酶更重要;PME的活性变化因品种而异,与耐贮性关系不大. 相似文献
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贮藏温度与超干处理对沙芥属蔬菜种子活力及抗脂质过氧化的影响 总被引：1，自引：0，他引：1
以沙芥种子（含水量4.5%）和斧形沙芥种子（含水量4.3%）为材料,采用硅胶干燥法将其含水量分别降至3.1%、2.2%、1.3%,在50、35 和20 ℃条件下密闭贮藏1年,研究温度对种子活力及抗脂质过氧化的影响,为种子老化及贮藏研究提供理论参考。结果表明,沙芥和斧形沙芥种子在50、35和20 ℃下贮藏1年,其贮藏最佳含水量范围随贮藏温度的下降而变宽,沙芥种子由4.5% ~ 3.1%变为4.5% ~ 2.2%,而斧形沙芥则从4.3% ~ 2.2%变为4.3% ~ 1.3%;种子活力的劣变先于发芽率的降低,随着含水量的降低,贮藏后种子的相对电导率有不同程度的增加,且以初始含水量（对照）种子的萌发、活力和生物膜完整性保持最好,斧形沙芥种子贮藏的最佳含水量范围和抗老化能力大于沙芥种子;贮藏过程加剧了种子的产生和MDA含量的积累,其中以35 ℃贮藏后积累最少;CAT、GPX、APX贮藏后活性保持良好且受贮藏温度的影响;本试验表明,贮藏的最佳条件为35 ℃,沙芥种子含水量为4.5%,斧形沙芥种子为4.3%。 相似文献
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以甘肃成县紫皮早蒜鳞茎种子为试材,在浓度为1.5×10~(-2) mol·L~(-1) NaCl的胁迫下,添加不同浓度的外源Zn~(2+)(1.0×10~(-6)、10~(-5)、10~(-4)、10~(-3)mol·L~(-1)),研究其对成县紫皮早蒜鳞茎种子萌发、幼苗生长、幼苗渗透调节物质的含量和4种抗氧化酶活性的影响。结果表明:在单一NaCl胁迫下,成县紫皮早蒜鳞茎种子萌发和幼苗的生长受到严重抑制,添加不同浓度Zn~(2+)后,大蒜鳞茎种子萌发率和幼苗的耐盐性明显增强;添加Zn~(2+)浓度为1.0×10~(-6)mol·L~(-1)时,大蒜鳞茎种子萌发率、萌发指数和芽长、根长、幼苗鲜质量、苗干质量、根鲜质量、根干质量、抗氧化酶SOD、POD、CAT和APX活性达到最大,可溶性糖、脯氨酸和丙二醛含量降到最低;因此说明,外源Zn~(2+)可以缓解NaCl胁迫对成县紫皮早蒜鳞茎种子萌发和幼苗的伤害;最适浓度为1.0×10~(-6)mol·L~(-1)。 相似文献
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采用硅胶干燥的方法对‘皖杂一号’和‘丰收2号’西瓜品种的种子进行超干贮藏试验,几种不同干燥水平处理的种子在室温条件下历经了23年的密闭贮藏,种子含水量分别降至2.32%和2.23%时,发芽率分别为96%和91%。种子发芽率的高低与其含水量呈显著负相关;过氧化物酶(POD)活性、干种子种胚蔗糖含量与发芽率的变化呈正相关,而超氧化物歧化酶(SOD)活性与发芽率的变化呈负相关。比较‘皖杂一号’超干贮藏9、15、20和23年后种子发芽率变化发现,当种子含水量≥5.22%,随着贮藏时间的延长,发芽率下降较快;种子含水量在1.65%~4.12%,发芽率下降缓慢,经20~23年密闭贮藏后仍保持较高的发芽率。本试验结果表明,二倍体西瓜种子在超干条件下贮藏可以长期保持良好的生活力。 相似文献
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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. 相似文献
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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. 相似文献
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《International Journal of Fruit Science》2013,13(1):139-156
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. 相似文献
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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. 相似文献
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Fulé Peter Z. Crouse Joseph E. Heinlein Thomas A. Moore Margaret M. Covington W. Wallace Verkamp Greg 《Landscape Ecology》2003,18(5):465-486
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. 相似文献
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《International Journal of Fruit Science》2013,13(3):101-120
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. 相似文献
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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. 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献