蓖麻DNA糖基化酶的序列与基因表达分析

为揭示DNA糖基化酶在调节蓖麻生长发育和影响基因印记过程中的分子机理,本研究基于蓖麻全基因组、利用生物信息学的方法结合转录组数据和RT-PCR半定量表达分析,鉴别蓖麻DNA糖基化酶氨基酸序列的结构特征、系统发生和表达形式。结果显示：三种DNA糖基化酶（DME、ROS和DML）氨基酸均为不稳定氨基酸,具有典型的与DNA结合和碱基切除修复有关的保守结构域;系统进化分析发现三种DNA糖基化酶在植物中同源性强,而且是独立演化的结果;在不同组织的表达上,蓖麻的DME和ROS基因具有相似的表达形式,即在根、茎和叶中不表达,在胚乳中表达最高,而DML在各个组织中都未检测到基因的表达。     

Influence of post-harvest treatments with fludioxonil and soy lecithin co-application in controlling blue and grey mould and fludioxonil residues in Coscia pears

The residue levels of fludioxonil (FLU) were determined in Coscia pear following a 1-, 2- or 4-min dip in an aqueous mixture of FLU containing 300 or 100 mg l^?1 (active ingredient, a.i.) at 20 and 50°C, respectively, with or without 2% soy lecithin. The efficacy of heat treatment with water and FLU mixtures was investigated on artificially inoculated pears for the control of post-harvest decay caused by blue (Penicillium expansum Link) and grey (Botrytis cinerea Pers. ex Fr.) mould. Treatment with 300 mg l^?1 FLU at 20°C increased residues significantly when treatment time rose from 1 to 2 min; no further increase was recorded when dip time raised from 2 to 4 min. FLU residue rates were unaffected by treatment time when 300 mg l^?1 a.i. was applied in combination with lecithin at 20°C. While treatment with 100 mg l^?1 a.i. at 50°C for 1 and 2 min resulted in similar residue levels, significantly higher residues were detected when dip time increased from 1 to 4 min. Co-application of lecithin significantly decreased FLU residues with respect to fruit treated with FLU alone. Treatments with FLU at 20 or 50°C effectively controlled decay over 10 days of incubation. While co-application of lecithin did not affect the efficacy of FLU at 300 mg l^?1and 20°C, treatment efficacy decreased when lecithin was applied in combination with 100 mg l^?1 FLU and 50°C for 4 min and to a greater extent when dip time was 1–2 min.     

Effects of various coatings and antioxidants on peel browning of ‘Bartlett’ pears

Peel browning of ‘Bartlett’ pears (Pyrus communis L) caused by various mechanical injuries during postharvest handling results in a reduction in visual quality. Various commercial and experimental coatings and antioxidants with potential to reduce peel browning of pears have been evaluated. Treatment with 0.2% diphenylamine (DPA) or 0.3% ethoxyquin (Eth) reduced peel browning on ‘Bartlett’ pears induced by vibration, rolling or scuffing. However, this effect only lasted for about 5 days when treated pears were stored at 0 °C. For the consideration of practical use, pears would have to be treated and packed shortly before transport to achieve a reduction in peel browning. DPA and Eth did not reduce peel browning on pears induced by handling at 20 °C after treatment. It is suggested that tight‐fill packaging and use of DPA or Eth would best reduce peel browning. Copyright © 2004 Society of Chemical Industry     

An above-ground biomass production model for a common reed (Phragmites communis Trin.) stand

A model is presented describing above-ground biomass production for a monospecific community of common reed (Phragmites communis Trin.), a perennial which is characteristically found in wetlands. The approach used follows the classic method applied to crop plants, namely the determination of stand phenology, and the establishment of the relationships governing leaf area production, light energy absorption by the leaves, and conversion efficiency of absorbed energy into biomass. The model also needed to take into account remobilisation of reserves accumulated in the rhizomes, which ultimately form a significant proportion of accumulated above-ground biomass. The final model was tested over two consecutive years, and produced promising results with regard to both the levels of production attained and the kinetics of the processes involved. The model can be used to determine production potential under given climatic conditions in its current form, and could even be applied to plant canopies with analogous biological characteristics, although scope remains for additional refinements.     

Effect of maturation and cold storage on the organic acid composition of myrtle fruits

BACKGROUND: The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold‐stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes. RESULTS: After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold‐stored fruits, malic acid rose to 3 g kg^?1 and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits. CONCLUSION: Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold‐stored berries. This parameter can be used as a marker of the onset of fruit senescence. Copyright © 2012 Society of Chemical Industry     

蓖麻成熟期胚抑制消减cDNA文库构建及其差异表达基因分析

利用抑制性消减杂交（suppression subtractive hybridization,SSH）技术,以高含油量蓖麻品种油蓖5号开花后第15d胚和36d胚为实验材料构建36d成熟期胚消减cDNA文库。文库的插入片段平均长度约400bp,随机挑取700个克隆进行PCR筛选,获得596个阳性克隆,经过点杂交筛选后选择了521个阳性克隆进行测序。经过同源性比对归并后得到96个差异表达基因,其中包括31个未知基因。已知基因涉及油脂合成、糖的分解、蛋白质贮藏与降解等多个方面。本研究还通过RT—PCR检测了部分可能与蓖麻油脂合成相关基因的差异表达水平,对其可能的功能进行了简要的分析。     

Sensorial and physicochemical quality responses of pears (cv Rocha) to long‐term storage under controlled atmospheres

Pears (cv Rocha) kept under controlled atmospheres (CA) and air were evaluated after long‐term storage in terms of sensory attributes and physicochemical parameters, namely colour, firmness, polyphenoloxidase (PPO) activity and concentration of hydroxycinnamic compounds. The CA conditions were all combinations of 2 and 4% (v/v) O₂ with 0.5 and 1.5% (v/v) CO₂. Storage under CA conditions produced a beneficial effect on ‘Rocha’ pears in maintaining their quality and, consequently, in extending their shelf life and acceptability. Clear differences in sensorial attributes, colour parameters and PPO activity were found between CA‐ and air‐stored pears. The effect provided by the CA conditions persisted throughout the time of exposure to the open air. The 2% O₂ concentration produced a more beneficial effect than its 4% counterpart on the sensorial and physical characteristics of the pears. The former concentration of O₂ prevented yellowing and allowed regular softening, hence keeping a high flavour quality. No clear effects could be associated with CO₂ levels. Empirical models were developed that describe the effects of O₂ and CO₂ concentrations, as well as time at room temperature on physicochemical parameters pertaining to ‘Rocha’ pears. Copyright © 2004 Society of Chemical Industry     

包装对巴旦杏仁油脂氧化和抗氧化能力的影响

以经过加工的去壳巴旦杏仁为材料,研究不同包装材料对其酸价、过氧化值、TBA值、总酚含量、VE含量和DPPH自由基清除能力的影响,以期了解包装材料对巴旦杏仁贮藏过程中油脂氧化和抗氧化能力的影响.结果表明:巴旦杏仁在贮藏过程中发生油脂的氧化酸败,表现为过氧化值和酸价上升,TBA值增加;采用EVOH共挤膜包装可显著降低其贮藏过程中酸价和过氧化值的增加幅度,抑制TBA值增加,减轻脂肪的氧化酸败;并保持较高的自身抗氧化物质总酚和VE含量,减缓DPPH自由基清除能力的下降,相对较好地维持组织的抗氧化能力.     

三根汤凉茶的工艺研究

以芦根、白茅根、蒲公英根为原料,通过水浸提、调配和高温杀菌等工艺处理,制备三根汤凉茶。研究表明,最佳浸提工艺为:芦根:94℃、浸提74min、料液比1:15.8g/mL;白茅根:96℃、浸提58min、料液比1:19.4g/mL;蒲公英根:86℃、浸提65min、料液比1:14.2g/mL。最佳配方为芦根汁40%,白茅根汁40%,蒲公英汁13%,白砂糖7%,柠檬酸0.1%。该产品色泽淡黄、澄清透明、具有三根汤凉茶特有的香味。