Zinc,copper, and iron nutrition studied with enriched stable isotopes

Enriched stable isotopes were used in nutrition studies of normal, healthy adults to measure zinc, copper, and iron absorption. After obtaining baseline values for zinc, copper, and iron absorption from diets adequate in all nutrients, the effects of age, pregnancy, and deveral dietary variables were studied. Stable isotopes of zinc, copper, and iron were incorporated into diets. Complete fecal samples were collected and the unabsorbed isotopes remaining in the samples were measured by thermal ionization mass spectrometry, the most precise analytical method for the determination of stable mineral isotopes. Stable isotopes were also infused in five young men to evaluate the potential of studying mineral utilization and kinetics with stable isotopes. The results of these studies demonstrate that a number of factors can affect mineral absorption, but the specific effects differ for different minerals. Isotopic enrichments could be measured in urine and blood, so kinetic studies of utilization of essential minerals are now feasible with enriched stable isotopes. Continued use of stable isotopes to determine mineral absorption, combined with stable-isotope studies of mineral utilization, balance data, and biochemical indicators of mineral status, should result in a better understanding of mineral requirements and metabolism under a variety of conditions.     

Stable isotopes in studies of intestinal absorption, exchangeable pools and mineral status: the example of magnesium.

Magnesium (Mg) is a biologically essential mineral and Mg deficiency is known to lead to severe biochemical and symptomatic disorders. Radioactive isotopes and, more recently, stable isotopes have been used as research tools to determine intestinal Mg absorption in humans and animals under different nutritional and physiological conditions. Mg isotopes are given orally or orally plus intravenously and analysed in faeces and/or in plasma and urine in order to calculate intestinal Mg absorption and possibly endogenous Mg excretion. Mg isotopes have been used to assess exchangeable pools of Mg under nutritional and physiopathological conditions. Mg isotopes are given intravenously and are analysed in plasma and urine to calculate the size and half-life of the various Mg exchangeable pools. More recently, in vitro isotopic tests have been developed to study the need of cells for Mg in different nutritional and genetic conditions. Whole blood is incubated with Mg isotopes and isotopic blood cell enrichment is measured, which reflects the avidity of cells for Mg and thus its initial status. This paper is a report on the use of stable Mg isotopes and their advantages in these different fields of Mg absorption and metabolism. The studies available have clearly demonstrated that stable isotopes provide a useful research tool for determining intestinal Mg absorption, and represent a precious research tool for the study of Mg metabolism and the assessment of Mg status.     

Stable isotope compounds - production,detection, and application

Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies.     

Effect of somatic and otolith growth rate on stable isotopic composition of early juvenile cod (Gadus morhua L) otoliths

The relative amounts of the stable isotopes of carbon and oxygen in fish otoliths can be used to reveal the environmental history experienced by the fish. This requires that the relative amounts of the isotopes are deposited in equilibrium with the surrounding environment, or that the offset from this equilibrium is known and can be quantified. It is known that carbon isotopes in biogenic carbonates are a mixture of carbon from the seawater and metabolically derived carbon, but the effect of the somatic growth rate of the fish is still unclear. The possible effect of otolith growth rate and fractionation of both carbon and oxygen isotopes are also not established. We carried out a controlled laboratory experiment where we reared cod (Gadus morhua L.) larvae and early juveniles at two temperatures (6 and 10 °C) and generated different growth rates within each temperature by manipulation of prey levels. The otoliths of the resulting fish were analysed for carbon and oxygen isotopes. We found no effect of otolith precipitation rate on fractionation of either carbon or oxygen isotopes. However, there was a depletion of ¹³C in the otoliths of fish with elevated metabolism. The proportion of metabolically derived carbon in the otoliths was estimated to be 28-32%. Our results suggest that measurements of oxygen isotopes in otoliths can be a reliable tool to estimate ambient temperature since the oxygen isotopes seem to be deposited in the otoliths independently of kinetic and metabolic effects. Fractionation of carbon isotopes in otoliths on the other hand can give valuable insight into metabolism and feeding pattern of fish.     

Differences in carbon and nitrogen stable isotope signatures amongst wild and released pheasant populations

Game birds such as pheasants Phasianus colchicus (Horsfield) are bred and released to supplement wild living populations prior to the hunting season. The total bag records of these birds are, therefore, not suitable for monitoring the development of wild populations because they are heavily influenced by game management. Wild and released pheasants can be expected to be genetically similar or identical to wild birds because wild birds are captured and used for breeding. It is, therefore, not possible to use genetic methods for identifying released individuals. Heavy stable isotopes are incorporated in animal tissues in a predictable manner and depend on the concentration of heavy isotopes in the diet. The heavy isotopes ¹³C and ¹⁵N accumulate in the food chain because the more common lighter isotopes are excreted at a higher rate than the heavy isotopes. Bred and released pheasant feed on a uniform plant-based diet, and it can, therefore, be expected that these animals have lower and less variable levels of heavy isotopes than individuals from a wild populations which feed on a diverse diet of plants and invertebrates. We investigated the isotope signatures in feathers from wild and released pheasant populations and compared the levels and variation in isotope signature amongst the populations. Bred and released pheasants are clearly identified in comparison to released pheasants as wild types have higher δ ¹⁵N.     

Can heavy isotopes increase lifespan? Studies of relative abundance in various organisms reveal chemical perspectives on aging

Stable heavy isotopes co‐exist with their lighter counterparts in all elements commonly found in biology. These heavy isotopes represent a low natural abundance in isotopic composition but impose great retardation effects in chemical reactions because of kinetic isotopic effects (KIEs). Previous isotope analyses have recorded pervasive enrichment or depletion of heavy isotopes in various organisms, strongly supporting the capability of biological systems to distinguish different isotopes. This capability has recently been found to lead to general decline of heavy isotopes in metabolites during yeast aging. Conversely, supplementing heavy isotopes in growth medium promotes longevity. Whether this observation prevails in other organisms is not known, but it potentially bears promise in promoting human longevity.     

Assessing temporal and spatial trends in estuarine nutrient dynamics using a multi-species stable isotope approach

Coastal urbanisation can alter estuarine nutrient dynamics through the input of point-source and diffuse pollutants, and nutrient concentrations can be highly influenced by seasonal and episodic rainfall and river flow. Understanding of both the spatial and temporal variability of nutrient dynamics is therefore critical to managing these estuaries. This can be achieved by periodically analysing the stable isotopes a range of aquatic taxa with variable nutrient turnover rates, mobility and distribution within the estuary. In two subtropical urban estuaries with different land use patterns, we analysed the carbon and nitrogen stable isotopes of phytoplankton, shrimp, prawns and fish at various proximities to pollution sources in dry and wet seasons. The fast nutrient turnover rates and ubiquity of phytoplankton in the estuary resulted in stable isotopes varying over fine-scale spatial scales, particularly in relation to proximity to point-source pollution. The slower nutrient turnover rates and localised habitat use of prawns, resulted in stable isotopes varying over larger spatial (between pollution sources) and temporal (seasonal) scales. The much slower nutrient turnover rates and high mobility throughout the estuary of fish resulted in stable isotopes varying over very large-scale spatial scales (between estuaries). These results illustrate a wide range of spatial and temporal changes to estuarine nutrient dynamics in subtropical urban estuaries in relation to rainfall conditions and nutrient inputs. This research also highlights the application of stable isotopes in assessing estuarine trophodynamics, and provides direction on the types of organisms that should be used to assess different spatial and temporal trends.     

Stable isotopes as tracers of organic matter input and transfer in benthic food webs: A review

Some of the ways that the application of stable isotopic tracers have contributed to the extremely hard task of understanding the energy and food web relations in benthic communities are illustrated in this review. Several methods are presented and their relative advantages are discussed, namely the use of endmembers, nitrogen isotopes, carbon isotopes, and sulfur isotopes. Special attention is given to the application of multiple tracers and transects sampling, natural and man-made perturbation experiments, and ¹⁵N additions as N cycle tracers.     

Do “heavy” eaters live longer?

A new hypothesis is put forward, linking cellular endurance with dietary consumption of stable heavy isotopes. Due to the isotope effect, biomolecules that incorporate heavier isotopes give rise to more stable molecular structures with increased resistance to damages associated with aging and age-related disease. The inclusion of heavy isotopes might be either active (selection for heavier isotopes) or passive (incorporation reflecting the existing abundance). The hypothesis links consumption of foods relatively rich in heavy isotopes (such as (13)C and D, derived from C4-plants), especially at the early stages of the organism's development, with enhanced longevity. Implications of diets and intestinal microflora are also discussed.     

Tracing water sources of terrestrial animal populations with stable isotopes: laboratory tests with crickets and spiders

Fluxes of carbon, nitrogen, and water between ecosystem components and organisms have great impacts across levels of biological organization. Although much progress has been made in tracing carbon and nitrogen, difficulty remains in tracing water sources from the ecosystem to animals and among animals (the "water web"). Naturally occurring, non-radioactive isotopes of hydrogen and oxygen in water provide a potential method for tracing water sources. However, using this approach for terrestrial animals is complicated by a change in water isotopes within the body due to differences in activity of heavy and light isotopes during cuticular and transpiratory water losses. Here we present a technique to use stable water isotopes to estimate the mean mix of water sources in a population by sampling a group of sympatric animals over time. Strong correlations between H and O isotopes in the body water of animals collected over time provide linear patterns of enrichment that can be used to predict a mean mix of water sources useful in standard mixing models to determine relative source contribution. Multiple temperature and humidity treatment levels do not greatly alter these relationships, thus having little effect on our ability to estimate this population-level mix of water sources. We show evidence for the validity of using multiple samples of animal body water, collected across time, to estimate the isotopic mix of water sources in a population and more accurately trace water sources. The ability to use isotopes to document patterns of animal water use should be a great asset to biologists globally, especially those studying drylands, droughts, streamside areas, irrigated landscapes, and the effects of climate change.     

Stable isotope views on ecosystem function: challenging or challenged?

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes.     

蜡质标本制作与保存对沉水植物稳定同位素的影响

实验通过模拟传统方法制作和保存蜡质标本, 旨在探究制作和保存的不同阶段对3种沉水植物碳、氮稳定同位素值的影响。结果表明, 制作和保存标本的过程均会对沉水植物的碳、氮稳定同位素值产生影响。植物标本压制的过程显著降低了沉水植物平均碳稳定同位素值, 其中马来眼子菜下降了1.78‰, 穗花狐尾藻下降了0.98‰, 金鱼藻下降了0.72‰。在压制过程中氮稳定同位素值只有金鱼藻显著下降了1.1‰。沉水植物标本制作的浸泡过程使穗花狐尾藻和马来眼子菜的碳稳定同位素值分别出现了1.00‰和0.52‰的上升, 金鱼藻的碳稳定同位素值增长小于0.08‰, 氮稳定同位素值没有显著变化。沉水植物对标本制作和保存的过程响应存在种间差异。在制作和保存过程中对植物碳稳定同位素产生的影响大于氮稳定同位素值。因此建议, 如果所研究对象的稳定同位素生态学差异小于3‰, 蜡质标本的样品需要进行实验校准, 不然会对结果产生影响。     

Martian Stable Isotopes: Volatile Evolution,Climate Change and Exobiological Implications

Measurements of the ratios of stable isotopes in the martian atmosphere and crust provide fundamental information about the evolution of the martian volatile and climate system. Current best estimates of the isotope ratios indicate that there has been substantial loss of gases to space and exchange of gases between the atmosphere and the crust throughout geologic time; exchange may have occurred through circulation of water in hydrothermal systems. Processes of volatile evolution and exchange will fractionate the isotopes in a manner that complicates the possible interpretation of isotopic data in terms of any fractionation that may have been caused by martian biota, and must be understood first. Key measurements are suggested that will enhance our understanding of the non-biological fractionation of the isotopes and of the evolution of the martian volatile system.     

Experiments on the Capture of Li,H, and D by Lithium Collectors at Different Surface Temperatures at the T-11M Tokamak

Prototypes of lithium emitters and collectors designed on the basis of capillary-porous systems (CPS) are being tried-out at the T-11M tokamak within the concept of continuous lithium circulation, previously proposed for stationary fusion neutron sources (FNSs). One of the goals of the T-11M tokamak research program are to implement the closure of the lithium circulation circuit and to develop the technology of recuperation (extraction and removal from the tokamak chamber) of hydrogen isotopes by using special lithium CPS-based collectors in order to prevent hydrogen isotope accumulation on the inner surface of the discharge chamber. In order to determine the optimal temperature regime for the future FNS operation, the effect of the temperature of the collector surface on its ability to capture lithium and hydrogen isotopes was studied. It is ascertained that the efficiency of capturing lithium and hydrogen isotopes by metal (12Cr18Ni10Ti) collectors in the operating regimes of the T-11M tokamak depends on the temperature of their collecting surfaces; namely, it remains almost constant in the temperature range from–196 to 50°С and then gradually decreases as the temperature rises to 300–400°С. In this case, the amount of the collected lithium is reduced by no more than sixfold, whereas the amount of collected hydrogen isotopes decreases by more than two orders of magnitude. Thus, the wall of a tokamak reactor chamber, which will be heated to 400°С but still coated with residual lithium (or its chemical compounds), will serve as a “mirror” for the incident hydrogen isotopes. It is found that the liquid lithium surface of the CPS-based collector can efficiently capture hydrogen isotopes falling onto it. As the lithium CPS-based collector is heated from 100 to 240°С, the amount of captured deuterium is reduced only twofold. This means that, in a steady-state mode, if, e.g., an MHD pump is used to transport liquid lithium from the collector back to the emitter, then, together with lithium, the captured hydrogen isotopes can also be transported into the recuperation zone.     

人指甲中氢、氧稳定同位素在法医学领域的应用

氢、氧稳定同位素作为一类化学示踪物质,在地理科学、环境生态和法庭科学等领域均有应用。在法庭科学研究领域,指甲作为一种记录人在不同时段内摄入氢、氧稳定同位素情况的载体,在推断人的生活地域变化轨迹方面具有很大的潜力,具有广阔的应用前景。本文从氢、氧稳定同位素溯源的基本原理,人指甲中氢、氧稳定同位素前处理方法和检验方法,人指甲氢、氧稳定同位素溯源技术的法医学应用等方面展开综述,并对稳定同位素溯源技术的发展等方面做了简要展望。     

Genetic action of 131I and 125I on the germ cells of male mice

A study was made of the genetic effects of iodine radioactive isotopes in male germ cells of (CBA X C57Bl)F1 hybrid mice. After a single intraperitoneal administration of Na131I (1.48 to 740 kBq/g) or Na125I (148 to 7400 kBq/g) to males the occurrence of dominant lethal mutations (DLM), reciprocal translocations (RT), and abnormal sperm heads (ASH) was studied. The radioactive iodine isotopes induced DLM at the postmeiotic spermatogenesis stages only. After the effect of the isotopes, the frequency of RT increased insignificantly with dose. The frequency of ASH was only increased with the highest 131I dose. Relative biological effectiveness of 131I and 125I was less than 1 with a reference to the indices under study.     

Pu同位素示踪技术在土壤侵蚀研究中的应用

土壤侵蚀是地球表面物质迁移的重要形式,也是造成土壤肥力下降和生态环境退化的重要诱因之一,对土壤侵蚀速率的定量研究是进行区域土壤侵蚀治理的前提和基础。大气核试验产生的Pu同位素具有较长的半衰期,其沉降到土壤中易被土壤中的黏土矿物和有机质吸附,近年来被认为是定量研究土壤侵蚀速率的重要示踪元素,尤其是质谱技术的发展,缩短了Pu同位素的测量时间并提高了其测量灵敏度,大力推动了土壤侵蚀核素示踪技术的发展。本文在梳理已有相关研究的基础上,总结土壤中Pu同位素的分布特征及吸附与迁移行为,阐述了应用Pu同位素示踪土壤侵蚀的基本原理和应用研究进展,并对Pu同位素和¹³⁷Cs示踪技术在土壤侵蚀研究中的适用性进行比较分析,对未来研究方向提出展望,以期为科学应用Pu同位素示踪技术研究土壤侵蚀提供参考。     

The application of stable isotopes in biomedical research

Many of the ways in which isotopes are used in biomedical research are reviewed. The use of stable isotopes in stable isotope dilution assays, for metabolite identification and in pharmacokinetic studies, is discussed and relevant examples are given to illustrate the various points made. Isotope effects and their implications for future drug design are considered. Some of the toxicity problems associated with the use of stable isotopes are also considered. Finally, a brief subjective view of possible future advances is made.     

脱甲河氢氧同位素组分时空分布特征及其影响因素

河水氢氧稳定同位素特征是研究水体转化和示踪水循环过程的重要内容.为研究河水氢氧稳定同位素特征,揭示河水补给来源,于2017年4—8月对亚热带农业小流域脱甲河4级河段(S_1、S_2、S_3和S_4)水体氢(D)、氧(¹⁸O)稳定同位素进行了监测,分析其时空动态特征和过量氘(d-excess)的变化规律,并探讨了它们与降水、高程和水质等影响因子的相关关系.结果表明:δD、δ¹⁸O和d-excess的变化范围分别在-43.17‰^-26.43‰(-35.50‰±5.44‰)、-7.94‰^-5.70‰(-6.86‰±0.74‰)和16.77‰~23.49‰(19.39‰±1.95‰).受季风环流的影响,δD和δ¹⁸O具有明显的季节变化特征,即春季(δD和δ¹⁸O为-29.88‰±3.31‰和-6.18‰±0.57‰)>夏季(δD和δ¹⁸O为-39.25‰±2.65‰和-7.32‰±0.42‰);空间上,δD和δ¹⁸O表现出明显的沿程变化,随着采样点的位置到河流源头的距离波动增加,δD为S_118O为S_118O与水温呈显著负相关(δD:r=-0.92;δ¹⁸O:r=-0.88);δ¹⁸O与海拔呈显著负相关(r=-0.96);在空间上,δ¹⁸O与水温呈显著正相关(r=0.98);δD和δ¹⁸O与降水量呈不显著负相关.     

Dietary change and stable isotopes: a model of growth and dormancy in cave bears.

In order to discuss dietary change over time by the use of stable isotopes, it is necessary to sort out the underlying processes in isotopic variation. Together with the dietary signal other processes have been investigated, namely metabolic processes, collagen turnover and physical growth. However, growth and collagen turnover time have so far been neglected in dietary reconstruction based on stable isotopes. An earlier study suggested that cave bears (Ursus spelaeus) probably gave birth to cubs during dormancy. We provide an estimate of the effect on stable isotopes of growth and metabolism and discuss collagen turnover in a population of cave bears. Based on a quantitative model, we hypothesized that bear cubs lactated their mothers during their first and second winters, but were fed solid food together with lactation during their first summer. This demonstrates the need to include physical growth, metabolism and collagen turnover in dietary reconstruction. Whereas the effects of diet and metabolism are due to fractionation, growth and collagen turnover are dilution processes.