水域生态学中生物稳定同位素样品采集、处理与保存

稳定同位素分析技术由于能够刻画复杂的食物网结构并追踪食物网中的能量流而成为水域生态学研究中的重要手段。但是当水生生物样品采集、处理和保存过程中存在不确定性时, 营养关系分析中的同位素结果可能会产生误导性解释。文章采用数据模拟分析和文献总结的方法, 研究了水域生态系统中样品采集、处理和保存对于稳定同位素的影响, 概括性地建议了水域生态系统中适合应用稳定同位素分析技术开展生态学研究的样品采集、处理和保存的注意事项。但今后仍需进一步评估样品采集、处理和保存对稳定同位素比值的影响效果, 确定化学动力学在水生生物样品采集、处理和保存中的作用, 以进一步完善水生生物样品的采集、处理和保存稳定同位素生态学研究规范。     

鸟类组织中稳定同位素周转率研究现状

稳定同位素分析技术被广泛应用于鸟类生态学多个方面的研究,如鸟类迁徙、营养级关系、生活史、食性等。根据不同的研究目的和要求,选择目标周期相对应的组织进行研究。在此前提下,掌握不同组织稳定同位素的周转率就显得尤为重要。目前国内有关鸟类组织稳定同位素周转率及其差异的研究较为有限,本文对国际上研究周转率的常见假说、方法和影响周转率的因素进行综述,旨在抛砖引玉,为利用稳定同位素技术开展鸟类学方面的研究提供依据。     

稳定同位素技术在鲨鱼摄食和洄游行为研究中的应用

随着稳定同位素分析技术的不断成熟,其在生态学领域中的应用也增长迅速,并成为动物摄食生态学的重要研究工具.鲨鱼因其在生物系统进化过程中的独特地位和海洋生态系统中的重要作用已成为海洋食物网研究的重点,然而国内针对鲨鱼摄食习性和洄游行为等方面的研究仍处于起步阶段.本文在总结了国内外鲨鱼稳定同位素分析组织样品选取和样品预处理方法的基础上,系统归纳了稳定同位素技术在鲨鱼摄食生态学,尤其在其摄食和洄游行为研究领域中的应用,着重分析稳定同位素技术在鲨鱼稳定同位素判别值和更新速率、食性分析、营养级评估、洄游路径分析和生态位分布等核心问题上的应用现状和发展前景,以期为国内学者开展鲨鱼类基础生物、生态学研究提供有益参考.     

基于稳定同位素的湿地食物源判定和食物网构建研究进展

湿地生物营养动力学是湿地生态系统结构和功能评价研究的基础.碳、氮稳定同位素作为识别营养关系的方法,已在湿地生态系统食物来源、组成和食物链传递研究中得到广泛运用.本文系统综述了稳定同位素食物贡献度计算模型和营养级确定的基本方法和理论;讨论了动物营养分馏值和基线的选择依据;概括了湿地生态系统典型食物源及其稳定同位素变化特征;总结了草食、杂食和肉食等不同营养级动物的食物来源.指出了稳定同位素在湿地食物源溯源和食物网研究中的不足;基于国内外研究现状和发展趋势及需求,展望了未来同位素技术在湿地食物网生态学研究中的运用前景和研究重点,提出需要加强稳定同位素营养分馏和基线的影响因素、样品处理和保存方式研究以及胃含物、分子标记物和多元素同位素结合分析.     

脂类抽提对北太平洋柔鱼肌肉碳、氮稳定同位素测定结果的影响

稳定同位素技术可深层次地分析头足类的摄食习性和栖息地等方面的重要信息.稳定同位素分析多选取动物肌肉为研究组织,然而,肌肉中的脂类含量会影响对其稳定同位素信息的准确解析.北太平洋柔鱼是重要的大洋经济性头足类,在海洋生态系统中具有重要的生态地位.本研究选取了53尾北太平洋柔鱼,通过分析脂类抽提对胴体肌肉稳定同位素比值的影响,探讨脂类物质对稳定同位素比值的干扰机制,对比不同碳稳定同位素比值校正模型的适用性,并提出适用于北太平洋柔鱼胴体肌肉δ¹³-C校正模型.结果表明： 北太平洋柔鱼肌肉的脂类抽提会引起稳定同位素测定结果的显著变化,δ¹³-C和δ¹⁵-N分别平均升高0.71‰和0.47‰,在分析组织碳稳定同位素比值时,脂类抽提在样品预处理过程中十分必要,其能消除脂类对样品稳定同位素分析的干扰,从而更加准确地分析研究对象食性与栖息地的变化.在单独进行氮稳定同位素比值分析时,则不需要进行脂类抽提.     

植物样品中碳、硫稳定同位素的测试

稳定同位素在其形成过程中记录了各种生态环境信息。进行植物中稳定同位素的分析,有助于植物的水分生理生态、光合作用、污染生态以及全球变化中的生态学研究。本文简要介绍了植物样品中稳定同位素碳、硫的形成过程、测试意义、样品制备及分析技术,碳同位素样品制备中的真空一高温炉法是在已有的安瓶小样法基础上改进而来,更具可操作性。标样测试表明该法分析的结果基本符合标准值。硫同位素分析样品的制备,采用艾氏卡试剂制取ＢａＳＯ＿４,三酸还原法制取Ａｇ＿２Ｓ,然后在高温炉中燃烧生成ＳＯ＿２,在质谱仪上进行测定．     

不同产地三疣梭子蟹的稳定同位素比值特征及原产地溯源

探索稳定同位素对三疣梭子蟹产地溯源的可行性,可为保护地理标志产品、追溯原产地来源提供理论依据。本研究以黄海、渤海和东海3个主产区海域的三疣梭子蟹为对象,分析了其碳、氮稳定同位素值差异性和不同组织中稳定同位素比值的相关性。结果表明: 不同产地的碳、氮稳定同位素比值有显著性差异,不同组织之间有明显的同位素分馏效应。利用建立的判别分析模型,通过三疣梭子蟹不同组织稳定同位素比值进行产地判别分析,采用肌肉和腮中碳、氮稳定同位素的产地判别正确率(>95%)明显高于肝胰性腺,说明肌肉和腮稳定同位素比值可以对不同海域的三疣梭子蟹进行有效区分。本研究填补了目前三疣梭子蟹稳定同位素溯源技术的研究空白。     

同位素标记相对和绝对定量蛋白组技术研究进展

近年来定量蛋白组学技术迅速发展,目前常用的有双向荧光差异凝胶电泳、同位素亲和标记、15N同位素标记、同位素标记相对和绝对定量和细胞培养条件下稳定同位素标记技术等。同位素标记相对和绝对定量技术以其高通量、高灵敏度、高重复性、高动态检测限和能对各种复杂样品进行相对和绝对定量研究等优势而备受研究者青睐,目前已发展到在同一实验中分析8组样品,增加了实验设计的灵活性。我们就同位素标记相对和绝对定量技术在定量蛋白组史中的地位作用、研究策略,以及在病毒致病机制研究和医药临床相关问题中的应用做简要综述。     

前处理与测试条件差异对化石牙釉质羟磷灰石稳定同位素数据的影响：以步氏巨猿动物群为例（英文）

牙釉质羟磷灰石的稳定同位素分析被广泛应用于古生物学研究之中,以重建古生态和古环境信息。在对不同研究中的同位素结果进行对比分析时,往往会忽略不同实验室、不同前处理方法可能引发的数据误差。为了探讨这些因素对牙釉质羟磷灰石同位素值的影响,重新测量了湖北省龙骨洞步氏巨猿动物群动物牙釉质样本的碳氧稳定同位素值,该批样本曾使用不同的前处理和实验方法进行过测试(Zhao et al., 2011; Nelson, 2014)。研究结果显示,重测的数据与Zhao et al.(2011)、Nelson (2014)发表的数据结果均存在一定差异。前处理方法与实验室测试差异都会造成牙釉质碳、氧稳定同位素结果的偏差。相较氧同位素而言,碳同位素值会更容易被前处理过程中反应试剂、反应时间等的不同所影响。但上述因素所导致的数据差异较小,不会对后续的分析产生实质性影响。本研究为直接对比不同来源牙釉质同位素值的可行性提供了初步的理论支持。建议为减少由于样品前处理和实验测试方案引发的数据误差,获得更加精确的研究结果,应尽可能采用同样的前处理与测试方案,多进行实验室间数据校正对比分析。     

稳定同位素技术在头足类摄食生态学研究中的应用

头足类在海洋食物网营养关系中占有重要地位,然而对其复杂的生活史过程,尤其是摄食生态学信息仍知之甚少.稳定同位素技术作为传统食物网科学研究方法的有力补充,可更深层次地分析头足类的摄食习性和栖息地等方面的重要信息.本文在比较分析国内外头足类摄食生态学研究方法的基础上,系统归纳总结了稳定同位素技术在头足类摄食生态学研究中的发展现状并介绍最新进展情况,着重分析稳定同位素技术在头足类生活史信息,尤其是在摄食生态学研究中的应用现状及发展前景,包括测定样品标准化、头足类生长发育过程中的食性转换和洄游分布等核心问题,以促进其在头足类生物学研究中的应用.     

稳定同位素技术在个体溯源中的应用

个体身份确认是自然灾害、空难、爆炸、火灾、交通事故等事（案）件处置中的一项重要工作。利用稳定同位素分布的地域差异性对个体进行溯源，可以为个体身份确认提供重要信息。本文简要介绍了稳定同位素技术原理，系统阐述了用于个体溯源的元素类型和不同人体组织中稳定同位素蕴含的特征信息，并对该技术在个体溯源中的应用现状、存在问题以及未来发展进行了分析和展望。     

Application of Stable Isotope Tracers to Studies of Zooplankton Feeding,using the Rotifer <Emphasis Type="Italic">Brachionus calyciflorus</Emphasis> as an Example

We present a protocol and calculation methods for the determination of zooplankton ingestion and assimilation rates with stable isotope tracers. These methods have been developed from experiments with the rotifer Brachionus calyciflorus that had been fed ¹³C-labelled Scenedesmus obliquus. Stable isotope tracers offer the same advantages as radioisotopes. These include the possibility for direct and accurate quantification of ingestion and assimilation rates, short sample analysis times and low animal densities requirements. However, the use of stable isotope tracers requires relatively long sample preparation times and specialist equipment and is, thus, relatively costly for most laboratories. The application of stable isotope tracers in zooplankton feeding studies offers several advantages in comparison with radioisotopes. Firstly, they do not emit harmful radiation and can therefore be applied safely both in the laboratory and in the field. Secondly, the samples can be dried for safe storage and easy transportation. Thirdly, no aggressive chemicals are required for sample analysis.     

Tissue turnover and stable isotope clocks to quantify resource shifts in anadromous rainbow trout

Stable isotopes can illuminate resource usage by organisms, but effective interpretation is predicated on laboratory validation. Here we develop stable isotope clocks to track resource shifts in anadromous rainbow trout (Oncorhynchus mykiss). We used a diet-switch experiment and model fitting to quantify N stable isotope (δ¹⁵N) turnover rates and discrimination factors for seven tissues: plasma, liver, fin, mucus, red blood cells, muscle, and scales. Among tissues, diet-tissue δ¹⁵N discrimination factors ranged from 1.3 to 3.4 ‰. Model-supported tissue turnover half-lives ranged from 9.0 (fin) to 27.7 (scale) days. We evaluated six tissue turnover models using Akaike’s information criterion corrected for small sample sizes. The use of equilibrium tissue values was supported in all tissues and two-compartment models were supported in plasma, liver, and mucus. Using parameter estimates and their uncertainty we developed stable isotope clocks to estimate the time since resource shifts. Longer turnover tissues provided accurate estimates of time since resource switch for durations approximately twice their half-life. Faster turnover tissues provided even higher precision estimates, but only within their half-life post-switch. Averaging estimates of time since resource shift from multiple tissues provided the highest precision estimates of time since resource shift for the longest duration (up to 64 days). This study therefore provides insight into physiological processes that underpin stable isotope patterns, explicitly tests alternative models, and quantifies key parameters that are the foundation of field-based stable isotope analysis.     

An assessment of sample processing methods for stable isotope analyses of marine food webs

Carbon and nitrogen stable isotope ratios are commonly used in the study of marine food webs. However, different sample processing methods can influence the measurement of these stable isotope ratios. The purpose of this study is to define an adequate methodology to be used in the construction of whole food webs. It is demonstrated that acidification of the samples results in a decrease in carbon stable isotope values for sedimentary organic matter, suspended particulate organic matter, plankton and invertebrates with carbonated structures. The response was variable for nitrogen isotope ratios. Based on our results we recommend sample acidification for carbon analysis in these compartments where effects of this treatment were observed. We observed a decrease in δ¹³C values after washing with distilled water, so we do not recommend washing with water after acidification. For nitrogen analysis, acidification should be avoided. The various dehydration treatments studied caused significant differences only in nitrogen isotope ratios.     

A novel strategy for quantitative proteomics using isotope-coded protein labels

Stable isotope labelling in combination with mass spectrometry has emerged as a powerful tool to identify and relatively quantify thousands of proteins within complex protein mixtures. Here we describe a novel method, termed isotope-coded protein label (ICPL), which is capable of high-throughput quantitative proteome profiling on a global scale. Since ICPL is based on stable isotope tagging at the frequent free amino groups of isolated intact proteins, it is applicable to any protein sample, including extracts from tissues or body fluids, and compatible to all separation methods currently employed in proteome studies. The method showed highly accurate and reproducible quantification of proteins and yielded high sequence coverage, indispensable for the detection of post-translational modifications and protein isoforms. The efficiency (e.g. accuracy, dynamic range, sensitivity, speed) of the approach is demonstrated by comparative analysis of two differentially spiked proteomes.     

The measurement of stable isotope natural abundance variations

Precise stable isotope natural abundance analysis of the elements of organic matter, yields a wealth of information for the biologist. Robust sample preparation methodology and analytical instrumentation is necessary to achieve precise results. Basic principles of isotope ratio mass spectrometry (IRMS) are detailed, with particular regard to sample size, gas production and transfer into the IRMS ion source. Gas preparation methods developed to give quantitative yields of pure simple gases from organic and inorganic materials include vacuum line combustion, ampoule combustion and automated elemental analysers used off and on-line. The new technique of GC-C-IRMS, where individual volatile organic compounds are separated by GC, combusted and analysed on-line by IRMS, is also described. The conventional dual batch inlet developed by geochemists for the most precise analysis of stable isotopes, is contrasted with continuous flow-IRMS analysis. The needs of the biological scientist for rapid throughput of small samples are discussed in this context. It is argued that the development of new instrumental approaches will permit many new applications of stable isotope methodology in the biological sciences.     

Freezing and chemical preservatives alter the stable isotope values of carbon and nitrogen of the Asiatic clam (Corbicula fluminea)

We tested the impacts of most common sample preservation methods used for aquatic sample materials on the stable isotope ratios of carbon and nitrogen in clams, a typical baseline indicator organism for many aquatic food web studies utilising stable isotope analysis (SIA). In addition to common chemical preservatives ethanol and formalin, we also assessed the potential impacts of freezing on δ¹³C and δ¹⁵N values and compared the preserved samples against freshly dried and analysed samples. All preservation methods, including freezing, had significant impacts on δ¹³C and δ¹⁵N values and the effects in general were greater on the carbon isotope values (1.3–2.2‰ difference) than on the nitrogen isotope values (0.9–1.0‰ difference). However, the impacts produced by the preservation were rather consistent within each method during the whole 1 year experiment allowing these to be accounted for, if clams are intended for use in retrospective stable isotope studies.     

Rapid and sensitive method for prenatal diagnosis of propionic acidemia using stable isotope dilution gas chromatography-mass spectrometry and urease pretreatment

Propionic acidemia is one of the most frequent inborn errors of metabolism caused by a deficiency of propionyl-CoA carboxylase. Methylcitric acid, a key indicator of this disorder, is increased in amniotic fluid when a fetus is affected. Therefore, the direct chemical analysis of cell-free amniotic fluid for methylcitric acid, using stable isotope dilution gas chromatography-mass spectrometry, was carried out for the prenatal diagnosis of propionic acidemia. We developed a simple, highly sensitive, and accurate method for quantitation of this polar methylcitric acid in amniotic fluids by applying a simplified urease pretreatment which we devised earlier for urine. As the recovery of methylcitric acid from amniotic fluid was as high as 91% with a coefficient of variation lower than 3% in this procedure, only 0.02 ml of sample was required for the analysis of the affected fetus. This new procedure takes 1 h for sample pretreatment, including derivatization, and 15 min for GC-MS measurement and provides final results within 1.5 h.