Regulation of the protein and gene expressions of ethylene biosynthesis enzymes under different temperature during peach fruit ripening

Ethylene has profound effect on fruit development and ripening, and the role of ethylene biosynthesis enzymes involving 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS), ACC oxidase (ACO), and S-Adenosyl-l-methionine synthetase (SAMS) in peach fruit (cv. Xiahui-8) was characterized under 25 and 4 °C, respectively. All these enzymes in ethylene synthesis pathway were identified using 2-DE and real-time PCR. Both protein and gene expressions of ACO and SAMS were much higher at 25 °C than at 4 °C. Among five members of ACS family, PpaACS4 may belong to system II ethylene biosynthesis, while PpaACS3 involved in system I during development stage, and low temperature can induce PpaACS1 expression. The ethylene release and low expressions of proteins and genes of most enzymes indicated that low temperature can effectively postpone ripening stage by reducing ethylene evolution. High gene expression of PpaSAMS did not cause excessive expression of SAMS protein under low temperature, and over-expression of PpaACS1 at low temperature still did not induce increase of ethylene production. The mechanism underlying the phenomenon about how temperature affects ethylene release was also discussed.     

Thermostability of photosynthesis in two new chlorophyllb-less rice mutants

Leaves of the two new chlorophyllb-less rice mutants VG28-1, VG30-5 and the wild type rice cv. Zhonghua 11 were subjected to temperatures 28, 36, 40, 44 and 48°C in the dark for 30 min or gradually elevated temperature from 30°C to 80°C at 0.5°C/min. The thermostability of photosynthetic apparatus was estimated by the changes in chlorophyll fluorescence parameters, photosynthetic rate and pigment content, chloroplast ultrastructure and tissue location of H₂O₂ accumulation. There were different patterns of F_o-temperature curves between the Chlb-less mutants and the wild type plant, and the temperature of F_o rising threshold was shifted 3°C lower in the Chlb-less mutants (48°C) than in the wild type (51°C). At temperature up to about 45°C, chloroplasts were swollen and thylakoid grana became misty accompanied with the complete loss of photosynthetic oxygen evolution in the two Chlb-less mutants, but chloroplast ultrastructure in the wild type showed no obvious alteration. After 55°C exposure, the disordered thylakoid and significant H₂O₂ accumulation in leaves were found in the two Chlb-less mutants, whereas in the wild type plant, less H₂O₂ was accumulated and the swollen thylakoid still maintained a certain extent of stacking. A large extent of the changes in qP, NPQ and F_v/F_m was consistent with the Pn decreasing rate in the Chlb-less mutants during high temperature treatment as compared with the wild type. The results indicated that the Chlb-less mutants showed a tendency for higher thermosensitivity, and loss of Chlb in LHC II could lead to less thermostability of PSII structure and function. Heat damage to photosynthetic apparatus might be partially attributed to the internal oxidative stress produced at severely high temperature.     

生物物种资源监测原则与指标及抽样设计方法

生物物种资源监测是了解生物物种资源现状、开展生物物种资源保护与管理的基础工作和重要手段.阐述了生物物种资源监测的科学性原则、可操作性原则和持续性原则.提出了监测计划的制定程序;监测计划应充分考虑所具有的人力、资金和后勤保障等条件,并进行定期评估.分析了指示物种在物种资源监测中的作用与不足;认为应选择具有不同生态需求和生活史的生物类群作为监测对象.讨论了监测指标的选取方法;监测指标应可测量、有科学基础、易被公众接受、低成本和高效益;监测方法应具有科学性,能检测到相应的变化,应采用高效率、低成本的标准化监测方法.分析了现有监测计划在抽样设计方面存在的问题,探讨了空间变异性和可检测率对监测数据误差的影响及其处理方式,讨论了样本量确定和监测样地的大小、形状及位置设计.监测样地要有较好的代表性,能在有限的监测面积中较好地反映监测区域内群落种类组成与数量特征.最后,讨论了生物物种资源监测的尺度和标准化问题.     

亚热带季风常绿阔叶林树木年轮的~(13)C/~(12)C和空气CO_2浓度变化

测定了亚热带季风常绿阔叶林的几种树木年轮的~(13)C/~(12)C比率(δ~(13)C)。云南银柴的1962—1983年年轮δ~(13)C平均为-28.53±0.84(n=5),华润楠的1951—1984年年轮的δ~(13)C为-28.46±0.53(n=6)。黄果厚壳桂的1951—1984年年轮的δ~(13)C为-29.19±0.80(n=6),木荷的1975—1984年年轮δ~(13)C为-28.42±0.41(n=4),δ~(13)C数值偏离平均值逐年增大。计算空气CO_2浓度每年递增1.21μ1/L。     

鼎湖山地区人类活动对马尾松年轮13C/12C的影响

南亚热带鼎湖山保护区的非核心地带的旅游活动和附近工厂区污染气体的排放,影响了 年轮中的δ＾１３Ｃ值和窃据的δα值。旅游点年轮的δ＾１３Ｃ值自１９６５－１９９２年以年均－０．０２６‰速率下降,１９８０－１９９２年年均下降速率增至－０．０４４‰。工厂点的年轮δ＾１３Ｃ则随时间而递增,气体污染改变了δ＾１３Ｃ值的年际变化图式。１９８０－１９９２年,对照点、旅游点和工厂点空气ＣＯ２浓度年均增高速率分别为０     

Ecotoxicological assessment of lanthanum with Caenorhabditis elegans in liquid medium

With their widespread applications in industry, agriculture and many other fields, more and more rare earth elements (REEs) are getting into the environment, especially the aquatic systems. Therefore, understanding the aquatic ecotoxicity of REEs has become more and more important. In the present work, Caenorhabditis elegans (C. elegans) was used as a test organism and life-cycle endpoints were chosen along with elemental assay to evaluate the aquatic toxicity of lanthanum (La), a representative of REEs. The results show La3+ had significant adverse effects on the growth and reproduction of worms above a concentration of 10 μmol L?1. The elemental mapping by microbeam synchrotron radiation X-ray fluorescence (μ-SRXRF) illustrated how La treatment disturbed the metals distribution in the whole body of a single tiny nematode at lower levels. Our results suggested that the high-level REEs in some polluted water bodies would lead to an aquatic ecological crisis. The assessment we performed in the present work could be developed as a standardized test design for aquatic toxicological research.     

余甘子的化学成分和保健功能作用

余甘子是一种具有较高的食用和药用价值的野生植物资源．风味独特．营养丰富,保健功能强,含有多种对人体有益的活性物质,具有补益、抗肿瘤、抗衰老等保健作用,这一特性使余甘子得到广泛关注,成为联合国卫生组织指定在全世界推广种植的三种保健植物之一。本文介绍余甘子的化学成分和保健功能作用,旨在促进余甘子的开发利用。     

伊犁贝母药用资源研究现状与开发前景

伊犁贝母的主要药用部位是鳞茎,具有清热化痰、润肺止咳的功效,野生伊犁贝母资源曾被滥采滥挖,导致其药用资源短缺,新疆多地开展了人工伊犁贝母培育工作,但仍有许多不尽人意之处。本文就伊犁贝母鳞茎中以西贝素为主要代表的生物碱的化学成分、药理活性、临床作用、栽培工艺、开发应用现状及前景等方面进行全面的综述,为伊犁贝母药用资源的进一步深入研究和开发提供有益的参考和对策。     

杆状病毒进化研究进展

杆状病毒的进化研究对于理解病毒的多样性十分重要,因此就杆状病毒基于单基因和基因组的进化研究方法、进化与变异、转座子与进化、与宿主共进化的相互关系进行了简要的总结和概括。