Aminoethoxyvinylglycine Effects on Late-Season Apple Fruit Maturation

Aminoethoxyvinylglycine (AVG) inhibits 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, and thus blocks ethylene synthesis. Preharvest foliar application of AVG to apple (Malus domestica Borkh.) fruit retards several key events of maturation including climacteric ethylene production, starch conversion to sugars, fruit softening, and abscission zone development. Although the impact of AVG on apple fruit maturation is well known, the biochemical basis of these effects is not well understood. The effects of AVG application on Redchief Delicious apple fruit maturation were studied. AVG applied four weeks prior to harvest significantly reduced internal ethylene levels, amylose degradation, and accumulation of sucrose, glucose, and sorbitol. Because AVG application coincidentally inhibited starch degradation and the increase in internal ethylene, we investigated the enzymatic basis of starch mobilization in apple fruit. Amylase activity was somewhat reduced in AVG-treated fruit. Amylase activity was less in AVG-treated fruit during the early stages of starch mobilization. Starch phosphorylase activity increased dramatically during the later stages of starch mobilization, but was not affected by AVG treatment. Soluble starch synthase activity was also unaffected by AVG treatment and remained constant throughout the eight-week harvest period. Moreover, AVG did not affect the levels of amylopectin, fructose, malate, ascorbate, citrate, or anthocyanin. These results suggest that apple fruit ripening has both ethylene-dependent and -independent processes occurring simultaneously.     

An in vivo experimental system to study sugar phloem unloading in ripening grape berries during water deficiency stress

An in vivo experimental system-called the 'berry-cup' technique-was developed to study sugar phloem unloading and the accumulation of sugar in ripening grape berries. The berry-cup system consists of a single peeled grape berry immersed in a buffer solution in a cup prepared from a polypropylene syringe. A small cross-incision (2 mm in length) is made on the stylar remnant of a berry during its ripening phase, the skin of the berry then being easily peeled off, exposing the dorsal vascular bundles without damaging either these or the pulp tissue of the berry. The sites of sugar phloem unloading are thus made directly accessible and may be regulated by the buffer solution. In addition, the unloaded photoassimilates are easily transported into the buffer solution in the berry-cup. With the berry-cup technique, it takes 60 min to purge the sugar already present in the apoplast, after which the amount of sugar in the buffer solution is a direct measure of the sugar unloading from the grape berry phloem. The optimum times for sampling were 20 or 30 min, depending on the type of experiment. Sugar phloem unloading was significantly inhibited by the inclusion of either 7.5 mm NaF or 2.5 mm PCMB in the buffer solution. This study indicates that sugar phloem unloading in ripening grape berries is via the apoplastic network and that the process requires the input of energy. The system was shown to be an appropriate experimental system with which to study sugar phloem unloading in ripening grape berries, and was applied successfully to the study of berry sugar unloaded from grapevines subjected to water stress. The results showed that water deficiency inhibits sugar unloading in grape berries.     

Possible Basic and Specific Functions of Plant Uncoupling Proteins (pUCP)

Evidence has been provided that the plant uncoupling proteins (pUCP) play basic physiological roles similar to the other uncoupling protein subfamily members (mammalian UCP1,2,3,4 and BMCP) and are effective in the situations of slight uncoupling that leads to: (1) accelerated respiration and metabolic rates that are beneficial to plant growth and development; (2) decreased formation of reactive oxygen species in mitochondria; and, (3) mild thermogenesis, inevitably accompanying the previous two phenomena. Hypothetically, specific physiological roles of pUCP such as cut off of ATP synthesis could be manifested in connection with climacteric respiratory rise during fruit ripening, seed dormancy, and plant senescence. pUCP might also facilitate growth under low temperatures, e.g., during seed germination or in roots. The existence of these specific roles is suggested by the immunochemical and functional localization of pUCP in mitochondria of fruits, seeds and roots of various plant species.     

The energy-conserving and energy-dissipating processes in mitochondria isolated from wild type and nonripening tomato fruits during development on the plant

Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, nonclimacteric) fruits. Fruit development was expressed in terms of evolution of chlorophyll a content allowing the assessment of a continuous time-course in both cultivars. Measured parameters: the cytochrome pathway-dependent respiration, i.e., the ATP synthesis-sustained respiration (energy-conserving), the uncoupling protein (UCP) activity-sustained respiration (energy-dissipating), the alternative oxidase(AOX)-mediated respiration (energy-dissipating), as well as the protein expression of UCP and AOX, and free fatty acid content exhibited different evolution patterns in the wild type and nor mutant that can be attributed to their climacteric/nonclimacteric properties, respectively. In the wild type, the climacteric respiratory burst observed in vitro depended totally on an increse in the cytochrome pathway activity sustained by ATP synthesis, while the second respiratory rise during the ripening stage was linked to a strong increase in AOX activity accompanied by an overexpression of AOX protein. In wild type mitochondria, the 10-M linoleic acid-stimulated UCP-activity-dependent respiration remained constant during the whole fruit development except in senescence where general respiratory decay was observed.     

Expression of cucumber lipid-body lipoxygenase in transgenic tobacco: lipid-body lipoxygenase is correctly targeted to seed lipid bodies

 A particular isoform of lipoxygenase (LOX, EC 1.13.11.12) localized on lipid bodies has been shown by earlier investigations to play a role during seed germination in initiating the mobilization of triacylglycerols. On lipid bodies of germinating cucumber (Cucumis sativus L.) seedlings, the modification of linoleoyl moieties by this LOX precedes the hydrolysis of the ester bonds. We analyzed the expression and intracellular location of this particular LOX form in leaves and seeds of tobacco (Nicotiana tabacum L.) transformed with one construct coding for cucumber lipid-body LOX and one construct coding for cucumber LOX fused with a hemagglutinin epitope. In both tissues, the amount of lipid-body LOX was clearly detectable. Biochemical analysis revealed that in mature seeds the foreign LOX was targeted to lipid bodies, and the preferred location of the LOX on lipid bodies was verified by immunofluorescence microscopy. Cells of the endosperm and of the embryo exhibited fluorescence based on the immunodecoration of LOX protein whereas very weak fluorescent label was visible in seeds of untransformed control plants. Further cytochemical analysis of transformed plants showed that the LOX protein accumulated in the cytoplasm when green leaves lacking lipid bodies were analyzed. Increased LOX activity was shown in young leaves of transformed plants by an increase in the amounts of endogenous (2E)-hexenal and jasmonic acid. Received: 9 August 1999 / Accepted: 28 September 1999     

Effect of some plant growth regulator treatments on apple fruit ripening

The activity of IAA oxidase (IAAox), peroxidases (POD), and polyphenoloxidases (PPO), as affected by different pre-harvest growth regulator treatments (ABA, AVG, NAA, PDJ), was determined in on-tree ripening apples (cv. Golden Delicious) before and during the ethylene climacteric. The production of ethylene was inhibited by AVG and delayed by NAA, whereas ABA and PDJ treatments caused, in the on-tree remaining fruits, a marked fruit drop and a decrease or a slight increase in ethylene levels respectively. While all treatments reduced POD activity, jasmonate increased IAAox and PPO activity. The inhibitory effect of NAA on all enzyme activity seems related to interference with C₂H₂ action or to a reduced sensitivity of the fruit abscission zone tissues to the hormone. The observed high fruit drop induced by ABA treatment made it impossible to detect differences in enzyme activity. AVG-treated fruits showed no substantial effects on IAAox and PPO activity in comparison to the control, a finding that seems to be related to a delay in all senescence processes caused by the very low level of the inhibited ethylene production. In control fruits IAAox activity increased during the initial ripening stages and decreased thereafter, POD activity increased throughout ripening and PPO showed little variation.     

两种高危型HPV检测技术诊断宫颈病变的临床价值比较

目的:比较酶切信号放大法(Cervista)与导流杂交基因芯片技术(Hybri Ma)检测高危型人乳头状瘤病毒(HR-HPV)诊断宫颈上皮内瘤变2级或2级以上(CIN2+)的临床价值。方法:随机选择288例2012年3月至2013年1月在哈尔滨医科大学附属第一医院妇科门诊进行新柏氏液基细胞学检查的年龄在20~65岁的宫颈细胞学检测未明确意义的不典型鳞状细胞(ASCUS)的患者,采用Cervista技术与Hybri Ma技术进行高危型HPV检测,并对入组的患者行阴道镜下宫颈活组织检查。以病理学诊断结果为金标准,比较Cervista技术与Hybri Ma技术诊断宫颈上皮内瘤变2级或2级以上(CIN2+)的敏感度、特异度及ROC曲线。结果:在入组的288例患者中,Cervista技术和Hybri Ma技术检出高危型HPV的阳性率分别为49.31%和51.39%(P0.05),其诊断CIN2+的敏感度分别为95.65%和91.30%(P0.05),特异度分别为59.50%和56.20%(P0.05),阳性预计值分别为30.99%和28.38%(P0.05),阴性预计值分别为98.63%和97.14%(P0.05)。两组ROC曲线下面积分别为0.776和0.738(P0.05)。结论:Cervista技术与Hybri Ma技术诊断CIN2+的临床价值相当。     

宫颈癌研究新进展

宫颈癌是威胁女性健康的最常见的主要恶性肿瘤之一,据统计全世界每年新发现有数万女性患有宫颈癌这种癌症,越来越多的妇女死于宫颈癌。宫颈癌也是一种预防的肿瘤,其致病因素多种多样,包括初次性生活的年龄、吸烟、HPV、HSV、HCMV、EBV等因素。目前的检测方法有巴氏涂片法、薄层液基细胞学涂片法、宫颈组织活检及宫颈管刮术、HPV-DNA检测、计算机辅助细胞学检测系统等方法可以诊断宫颈癌。早期诊断、早期检查对宫颈癌的预防和治疗具有积极作用,同时降低宫颈癌的死亡率。     

脊髓型颈椎病的发病机制及治疗的研究进展

在中老年人群中脊髓型颈椎病是造成脊髓功能障碍的主要原因,其发病机制复杂,主要有静态和动态因素、缺血、内皮细胞损伤和血脊髓屏障的破坏、炎症及细胞凋亡等学说,每一种学说并不能够完美的解释脊髓型颈椎病的发病机制,仍需进一步实验研究探索其机制。对于进行性发展的脊髓型颈椎病多采用手术治疗,手术方式主要有前路、后路及前后路联合手术,如何选择手术方案仍是临床医生关注的焦点,本文就该病的发病机制及手术治疗的相关进展作一综述。     

苦参碱对大鼠宫颈癌组织中Survivin、Caspase-3和Caspase-7表达的影响

目的:探讨苦参碱对宫颈癌模型大鼠组织中Survivin、Caspase-3和Caspase-7的表达影响。方法:选取Wistar雌性大鼠34只,宫颈癌造模成功的19只分成阴性对照组(A组)和苦参碱组(B组);未造模的10只大鼠作为正常对照组(C组)。采用免疫印迹法检测三组大鼠宫颈癌组织中Survivin、Caspase-3和Caspase-7表达水平。结果:1A组大鼠组织中Survivin表达明显高于B、C组大鼠组织中Survivin水平,差异有统计学意义(P0.05);2A组大鼠组织中Caspase-3和Caspase-7的表达明显低于B、C组,差异有统计学意义(P0.05);3B组大鼠组织中Survivin、Caspase-3和Caspase-7的表达水平与C组比较存在差异,差异有统计学意义(P0.05)。结论:苦参碱能够明显下调宫颈癌大鼠凋亡抑制因子Survivin水平,改善凋亡因子Caspase-3和Caspase-7的表达。