不同采收成熟度油桃贮藏效果及果肉细胞超微结构观察

以秦光2号油桃果实为材料,在0℃贮藏条件下研究了5个采收成熟度果实的贮藏效果及果肉细胞超微结构的变化。结果表明,(1)处理Ⅳ成熟度果实贮藏40d后能保持相对较高的硬度和可溶性固形物,货架期品质好,好果率高,贮藏效果好,为最佳采收成熟度。(2)采收当天的处理Ⅰ、Ⅱ、Ⅲ成熟度的果实,果肉细胞的超微结构无明显差异;处理Ⅳ成熟度果实,叶绿体开始变形,细胞外壁开始有少许微纤丝松懈;处理Ⅴ成熟度果实,细胞壁中胶层开始溶解,电子密度降低,出现质壁分离和液泡破损现象。(3)贮藏50d后,不同成熟度的果实,果肉细胞的超微结构都发生明显变化,显示出果肉细胞间隙增大,细胞内含物减少,出现细胞空腔化;细胞壁中胶层降解,细胞壁弯曲或皱缩,质壁分离严重;细胞器变形或降解等现象。     

不同溶质桃果实的软化与乙烯合成相关基因的差异表达

以八成熟Stonyhard型桃‘霞脆’和‘有名白桃’、软溶质桃‘银花露’、硬溶质桃‘湖景蜜露’、不溶质桃‘金童6号’的果实为试材,研究了25 ℃和4 ℃贮藏条件下果实软化及乙烯生物合成途径相关基因表达水平的差异。结果显示：两种贮藏温度下,Stonyhard型桃‘有名白桃’和‘霞脆’果实释放极少量乙烯;25 ℃常温条件下,Stonyhard型桃果实硬度保持较高水平,但4 ℃低温诱导了‘有名白桃’果实软化。实时荧光定量PCR表明,软溶质、硬溶质和不溶质桃的PpACS1基因均具有高表达丰度,而Stonyhard型‘霞脆’和‘有名白桃’的表达水平极低;两种贮藏温度下,5个桃品种果实在整个贮藏期间均未检测到PpACS2和PpACS3基因的表达。此外,低温诱导了PpACO1基因在Stonyhard型桃‘霞脆’和‘有名白桃’中的表达,‘有名白桃’果实endo-PG基因受低温刺激表达也上调。说明不同肉质类型的桃贮藏期间果实软化与乙烯的生物合成关系密切,不同温度下通过调节相关基因的表达水平进而调控果实软化进程。     

不同质地桃果实软化过程中细胞壁组分变化的差异

以不同质地的桃果实为试材,采用测定乙醇不溶性物质(alcohol insoluble solids,AIS)及总果胶和水溶性果胶等相关指标的方法,研究了细胞壁组分变化的差异对不同质地桃果实软化过程的影响,以期阐明在成熟软化过程中不同质地桃果实的细胞壁组分的变化差异。结果表明:不同质地桃品种软化过程中细胞壁组分含量变化存在明显差异。软溶质桃在贮藏初期乙醇不溶性物质和纤维素含量迅速下降;在整个贮藏期间,软溶质桃的总果胶含量显著低于硬溶质和不溶质品种,而其水溶性果胶含量在贮藏的前期和中期一直保持较高水平。硬溶质和不溶质桃在整个贮藏期间细胞壁组分AIS、总果胶和纤维素含量均相近,且变化规律相似,即含量一直相对保持稳定,变化幅度较小。此外,水溶性果胶含量变化在溶质和不溶质桃之间存在明显差异。不溶质桃在整个贮藏期间水溶性果胶含量基本保持稳定,仅在贮藏后期缓慢升高;而溶质桃在贮藏中期水溶性果胶含量显著升高。     

不同肉质桃果实成熟过程中细胞壁相关酶活性变化

以软溶质型“霞晖5号”、硬溶质型“保佳红”、硬质型“保佳俊”、不溶质型“金童6号”桃果实为试材，采用果实细胞壁降解相关酶活性测定方法，研究了不同肉质桃果实成熟过程中硬度、呼吸强度、细胞壁降解相关酶活性及基因PG21、PME的表达差异对果实软化的影响，以期阐明不同肉质桃果实成熟过程中细胞壁相关酶活性变化差异。结果表明：软溶质型桃“霞晖5号”果胶甲基酯酶(PME)、纤维素酶(Cx)活性高于其它3种肉质类型的桃果实，多聚半乳糖醛酸酶(PG)活性高于不溶质型桃“金童6号”和硬质型桃“保佳俊”,表明PG、PME、Cx活性与软溶质型桃“霞晖5号”软化进程密切相关。4种肉质类型的桃果实β-半乳糖苷酶(β-gal)活性差异不显著，表明β-gal不是影响不同肉质类型的桃软化进程的关键因素。4种不同肉质类型的桃果实在成熟发育后期PG21基因相对表达强度整体呈上升趋势，“霞晖5号”和“保佳俊”PME基因相对表达量在整个果实发育后期均呈上升的趋势，酶活性与相关基因表达量变化趋势基本一致。     

桃和油桃的贮藏

桃和油桃在市场供应过剩、进行运输或延长加工期时,要进行贮藏。一般在-0.5～0℃条件下可贮藏2～4周。超过3～4周再移到较高温度时,一般不能很好的后熟,其果肉特别是果核周围会变干而松散、湿软显著变褐。冷藏前在21～24℃下后熟1～3天可减轻这种褐变的程度。贮于2～5℃条件下会引起特别重的内部褐变,0℃下贮藏1～2周的果实移至5℃环境中,也会引起严重的褐变。10℃下贮藏的桃不发生褐变,但果肉会迅速变软。桃后熟的适宜温度一般在18℃～29℃之间。硬熟期采收的桃和用作加工的桃经常需分4～6k的后熟。一般来说,贮藏后进行后热比贮藏前进行后…     

李果实在高温下贮藏性及品质的变化

对东北李主栽品种绥李３号果实在２０、３０、３５、４０℃高温条件下的贮藏性和品质变化进行了研究。结果表明，在３０℃下贮藏，商品性能保持１５ｄ，与２０℃下贮藏相比约延长１５ｄ。３５℃下没有显著地软化，与３０℃大体相似，在４０℃下贮藏３－４ｄ能保持商品性，以后则发生腐败。３０℃贮藏３ｄ后移入２０℃贮藏，品质显著提高，但３０℃７ｄ后移入２０℃，贮藏时间虽可延长，但品质没有提高。而且３０℃贮藏后移入２０℃果实的硬度、果皮及果肉颜色的变化差异显著。各温度段的贮藏糖度、酸度变化差异都比较显著。     

1-甲基环丙烯和温度对桃和油桃贮藏品质的影响

 以‘秦光2 号’油桃和‘秦王’桃为试材, 在0 ℃和5 ℃两种贮藏温度条件下研究了1-甲基环丙烯(1-MCP) 对果实呼吸速率、乙烯释放速率、硬度、可滴定酸含量、可溶性固形物含量及果肉褐变的影响。结果表明, 0 ℃的贮藏温度能显著降低秦光2号油桃和秦王桃的呼吸速率和乙烯释放速率, 减缓果实软化。1μL·L ^-1的1-MCP 处理能降低果实的呼吸速率和乙烯释放速率, 抑制果实软化, 减少果肉褐变,但对可滴定酸和可溶性固形物含量无明显影响。     

晋虞1号桃简易气调贮藏试验研究

研究了晋虞1号桃在0℃下简易气调贮藏效果。结果表明:PVC+高效乙烯去除剂、PVC保鲜袋、PVC硅窗袋处理可有效地减少果实腐烂和果肉褐变,延缓果实硬度的下降,明显减轻果实冷害的发生,提高桃果实贮后品质,以PVC+高效乙烯去除剂处理效果最好,对照PE薄膜打孔袋处理贮藏效果较其他3个处理差。     

不同成熟度番茄果实在贮藏期间的品质变化

以京采8号为试材，研究不同成熟度番茄果实在4℃条件下随贮藏时间的品质变化，并利用番茄品质指数（TQI）对果实品质进行综合评价。结果表明：不同成熟度番茄果实的硬度均随贮藏时间的延长呈逐渐降低趋势，可溶性固形物、VC含量和糖酸比分别在贮藏3、7、7 d时最高，硝酸盐含量在贮藏3 d时最低；半熟期和坚熟期果实的可溶性糖含量在贮藏3 d时最高，完熟期果实的可溶性糖含量则在贮藏7 d时最高；半熟期和完熟期果实的有机酸含量在贮藏1 d时最高，坚熟期果实的有机酸含量则在贮藏3 d时最高；不同成熟度果实的TQI在贮藏3 d和7 d时较高。综合来看，半熟期、坚熟期和完熟期的果实，采收后在4℃条件下分别贮藏7、3、3 d，可在延长番茄货架期的同时获得果实最佳综合品质。     

桃果实肉质研究进展

桃果实以皮薄肉厚、味道鲜美、营养丰富等优点而深受国内外消费者喜爱。然而桃果实属于呼吸跃变型果实,且成熟期集中在夏季高温季节,采后迅速软化,导致果实品质下降、不耐贮藏及货架期短,是制约桃产业可持续发展的关键问题。前人研究发现桃果实具有不同的肉质类型,这其中也包含较耐贮运的肉质,为了解桃果实肉质的研究概况,笔者归纳总结了国内外关于桃果实肉质类型的分类及遗传定位、桃果实不同肉质形成的分子机制等方面的研究进展,并提出了存在的不足以及未来研究趋势。指出目前桃果实肉质的研究局限于果实成熟软化过程中细胞壁结构和相关物质的变化、细胞壁降解相关酶的活性变化,以及这些酶的基因克隆,认为未来激素调控桃果实成熟软化的转录调控机制,同时结合基因组、转录组、蛋白组和代谢组等多组学的研究将是桃果实肉质研究的重点方向。     

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.