基于VRP模型环状管网优化设计的研究

给水工程中环状管网的优化设计对于降低整个工程造价起到重要作用。提出了基于VRP模型环状管网优化模型的构建,并利用MMAS算法对优化模型进行求解。以青海某科技示范园为例,详细介绍了环状管网优化模型的设计步骤,讨论了模型构建的方法、目标函数的组成、约束条件的形式。结果表明:利用MMAS算法求解,模型运行稳定,求解效率高,环状管网布置得到了优化,对实际工程具有应用价值。     

根癌农杆菌介导的磨盘柿遗传转化体系的优化

以磨盘柿叶片为外植体,通过农杆菌介导法,建立了ACC合成酶基因(ACS)遗传转化体系。研究了预培养时间、农杆菌菌液浓度、侵染时间、共培养时间和乙酰丁香酮(AS)浓度等因素对基因转化的影响。结果表明:适宜的预培养时间为2 d;用OD600值为1.0的菌液侵染15 min、共培养3 d,AS浓度200μmol/L有利于提高转化频率。经PCR分子检测,初步确定ACC合成酶基因已转入磨盘柿组培苗中。     

梯级水库优化调度模型的蚁群系统(ACS)算法求解研究

【目的】对梯级水库调度模型的动态、高维、非线性、复杂优化问题进行求解。【方法】在传统蚂蚁系统的基础上,将蚁群系统中的蚁密、蚁量系统的局部更新和蚁周系统的全局更新有机结合,提出了一种求解梯级水库优化调度模型的改进蚁群算法,即蚁群系统(ACS)算法,采用ACS算法对乌江梯级水库进行了优化调度实例研究。【结果】ACS算法兼顾了计算的时间和精度,优化得乌江梯级发电量为96.538亿kW·h,相比利用动态搜索算法求解的乌江梯级发电量95.882亿kW·h略大,但均接近于乌江梯级设计多年平均发电量100.21亿kW·h。【结论】采用ACS算法可快速求解乌江梯级水库优化调度模型,并可得到满意的结果,说明该优化算法是合理、可行的。     

利用体外产气法评定不同比例氨化秸秆替代苜蓿的组合效应

试验旨在研究苜蓿（alfalfa meal,AM）和氨化秸秆（ammoniated corn straw,ACS）的最佳组合比例,以提高粗饲料的利用率并降低饲养成本。将AM与ACS分别以100：0、80：20、60：40、50：50、40：60、20：80和0：100比例进行混合,每种组合3个重复,利用体外产气法评定不同组合发酵3、6、12、24、48 h的累积产气量（GP）,及发酵48 h时发酵液pH、干物质降解率（DMD）、氨态氮（NH₃-N）、微生物蛋白（MCP）和挥发性脂肪酸（VFA）浓度,进而计算不同组合的单项组合效应指数（SFAEI）和多项组合效应指数（MFAEI）。结果显示,发酵48 h时,AM20：ACS80组的累积产气量最高;而AM0：ACS100组的DMD显著低于其余各组（P<0.05）;AM20：ACS80组和AM0：ACS100组的NH₃-N浓度显著高于其他组（P<0.05）;AM20：ACS80组MCP浓度最高;AM20：ACS80组的乙酸和总挥发性脂肪酸（TVFA）浓度显著高于其他组（P<0.05）,各组乙酸/丙酸的比值均大于3,属于乙酸发酵型;发酵期间各组pH的变化范围为6.69~6.85。以MFAEI和SFAEI对各项指标进行评定时,仅有AM20：ACS80组出现正组合效应。由此可见,AM和ACS的比例为20：80时组合效应最佳。     

Ethylene biosynthesis in apricot: Identification of a ripening-related 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene

Apricots are climacteric fruits with a high susceptibility to flesh softening and loss of flavor during postharvest storage, and most of the ripening processes are regulated by ethylene, which also has an effect on its own biosynthesis. To understand this process in apricot, inhibition of ethylene biosynthesis and perception was performed for studying key genes involved in the ethylene biosynthetic pathway. Apricots, cv. “Patterson”, were harvested with yellow-green ground color and immediately treated with either the ethylene perception inhibitor 1-methyl cyclopropene (1-MCP) at 10 μL L⁻¹ or the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) at 1 g L⁻¹. After treatment, quality and physiological attributes such as firmness, color, total soluble solids, acidity, fruit weight, ethylene production and respiration rates were evaluated every 2 d until they ripened at 20 °C. Gene expression analysis was performed by quantitative polymerase chain reaction (qPCR). Both ethylene inhibitors were effective in reducing ethylene production, respiration rate and fruit softening. Three 1-aminocyclopropane-1-carboxylic-acid synthase (ACS) genes were characterized, but only the expression of ACS2 was highly reduced by ethylene inhibition, suggesting a key role in ethylene synthesis at ripening. Contrarily, ACS1 and ACS3 showed a higher expression under ethylene inhibition suggesting that the corresponding genes are individually regulated in a specific mode as observed in other climacteric fruits. Finally, changes in 1-aminocyclopropane-1-carboxylic-acid oxidase genes did not show a consistent pattern of ethylene modulation.     

Mode of action of nitric oxide in inhibiting ethylene biosynthesis and fruit softening during ripening and cool storage of ‘Kensington Pride’ mango

The mode of action of nitric oxide (NO) in inhibiting ethylene biosynthesis and fruit softening during ripening and cool storage of mango fruit was investigated. Hard mature green mango (Mangifera indica L. cv. ‘Kensington Pride’) fruit were fumigated with 20 μL L⁻¹ NO for 2 h at 21 °C and allowed to ripen at 21 ± 1 °C for 10 d, or stored at 13 ± 1 °C for 21 d. During ripening and cool storage, ethylene production and respiration rate from whole fruit were determined daily. The 1-aminocyclopropane-1-carboxylic acid (ACC) content, activities of ACC synthase (ACS), ACC oxidase (ACO), and fruit softening enzymes such as pectin esterase (PE), endo-1,4-β-d-glucanase (EGase), exo- and endo-polygalacturonase (exo-PG, endo-PG) as well as firmness and rheological properties of pulp were determined at two- and seven-day intervals during ripening and cool storage, respectively. NO fumigation inhibited ethylene biosynthesis and respiration rate, and maintained higher pulp firmness, springiness, cohesiveness, chewiness, adhesiveness, and stiffness. NO-fumigated fruit during cool storage and ripening had lower ACC contents through inhibiting the activities of both ACS and ACO in the fruit pulp. NO-fumigated fruit showed decreased activities of exo-PG, endo-PG, EGase, but maintained higher PE activity in pulp tissues during ripening and cool storage. In conclusion, NO fumigation inhibited ethylene biosynthesis through inhibition of ACS and ACO activities leading to reduced ACC content in the fruit pulp which consequently, reduced the activities of fruit softening enzymes during ripening and cool storage.     

芍药‘桃花飞雪’开花衰老期间乙烯代谢生理机制的研究

以芍药（Paeonia lactiflora Pall.）品种‘桃花飞雪’为试材,测定了不同发育时期花枝以及花瓣的呼吸速率、乙烯释放速率、ACC含量、ACS和ACO活性的变化。结果表明：芍药切花花瓣的乙烯释放速率有明显的跃变峰,整枝花乙烯释放表现为末期上升型。花瓣与花枝呼吸速率均有明显的跃变,花瓣的跃变峰早于整枝花。花瓣的乙烯释放速率及呼吸速率均明显高于花枝,揭示花瓣是花枝产生乙烯的主要器官,花瓣的乙烯释放决定了花枝的开放与衰老进程。花瓣ACS活性与乙烯释放量的变化趋势较为一致,说明ACS是影响乙烯生物合成的限制因子。     

ACS基因和HBsAg基因的克隆及瞬时表达分析

本研究通过SDS法从香蕉幼嫩叶片中提取基因组DNA,通过PCR的方法对ACS启动子2.5Kb的序列进行缺失改造,克隆到了长1 185bp的ACS启动子片段,与GenBank报道序列相比较同源性为93.2%.经PlantCARE软件分析发现序列中含有多种调控元件,经预测ACS启动子可能被光、热、GA、乙烯或伤所诱导.为验证其果实特异表达活性,通过插入到pBI 101.2中间表达载体上的GUS基因5＇端前,构建了含GUS基因的瞬时表达载体pBACS.用基因枪法将pBACS转化到香蕉果实中,结果表明：用pBACS包被的金粉轰击的果实经GUS组织化学染色后,都出现兰色斑点,对照没有出现兰色斑点.因此认为GUS基因在香蕉果实成功实现瞬时表达.同时,通过改进的酚-氯仿提取法从乙肝病毒感染者的血清中提取总DNA,然后根据报道的序列设计特异性引物,同时在上游引物中引入了Kozak序列,经PCR克隆到HBsAg基因序列,长度为681bp.NCBI BLAST分析的结果表明,获得的HBsAg基因序列及推导的氨基酸序列与GenBank中所报道的序列的同源率分别为97.2%和97.4%.将经过改造的HBsAg基因替代pBACS中的GUS基因,成功构建了含有ACS启动子和HBsAg基因的香蕉树果实表达载体,为下一步转化香蕉,获得在果实中表达HBsAg蛋白的转基因植株奠定了基础.     

转反义ACS加工番茄材料的获得及其当代表现

采用农杆菌介导法将反义ACS基因导入加工番茄美东、UC-82中,用Southern杂交检测所获得的9株再生植株,结果表明有3株再生植株的染色体中有外源基因的插入。所获得的再生植株在基因转化处理当代表现各异,其中3号植株成熟延迟明显。果实转红后的色泽与对照在感官上无明显差异。转基因植株的表型观察与分子检测结果相吻合。     

Ethylene treatment of ‘Hayward’ kiwifruits (Actinidia deliciosa) during ripening and its influence on ethylene biosynthesis and antioxidant activity

The aim of this investigation was to assess the influence of ethylene treatment on ethylene biosynthesis and on antioxidant activity in kiwifruits during ripening. Kiwifruits were treated with ethylene of 100 μg ml⁻¹ at 20 °C for 24 h and then the ripening process at the same temperature was observed for 10 additional days. It was found that in treated fruits: (a) the flesh firmness in the early stage of ripening was significantly decreased in treated samples, (b) the contents of free sugars, soluble solids, ethylene, respiration and sensory value were increased and were significantly higher than in untreated fruits, (c) the ethylene biosynthesis was increased simultaneously with increase in 1-aminocyclopropane-1-carboxylic acid (ACC) content, ACC synthase (ACS) and ACC oxidase (ACO) activities, (d) the polyphenols content and the related antioxidant activity were increased significantly higher than in the untreated fruits and (e) the acidity and pH were not influenced by ethylene treatment.