Measurements of mineralization process in the femur growth plate and rib cartilage of the mouse using pixe in combination with a proton microprobe

The femoral bone from the 18-day pregnancy embryo and an rib cartilage of mature mice have been investigated using PIXE (proton induced X-ray emission) in combination with a proton microprobe on snap frozen cryosectioned material. The localization and the results of quantitative measurement of P, S, Cl, K, Ca, Fe and Zn have been correlated with the histochemical localization of inorganic deposits. It has been found that in calcifying and degenerating cartilage of the growth plate there is substantial loss of S; this element being indicative for sulphate groups of glycosaminoglycans. This change seems to be an important factor conditioning the process of mineralization. Zn is found in higher concentration in mineralized tissues, both in embryonal and mature cartilage as well as in the bone, and this suggests that Zn is also involved in the mineralization process. The mineralization of rib cartilage exceeds that of embryonal bone, and the Ca/P ratio is higher in the former than in the hydroxyapatite of the latter. The method described is a useful analytical tool especially for such types of studies in which elements are not easily redistributed by freezing, cutting and drying; e.g. in investigations of mineral deposits.     

Measurements of mineralization process in the femur growth plate and rib cartilage of the mouse using pixe in combination with a proton microprobe

Summary The femoral bone from the 18-day pregnancy embryo and an rib cartilage of mature mice have been investigated using PIXE (proton induced X-ray emission) in combination with a proton microprobe on snap frozen cryosectioned material. The localization and the results of quantitative measurement of P, S, Cl, K, Ca, Fe and Zn have been correlated with the histochemical localization of inorganic deposits. It has been found that in calcifying and degenerating cartilage of the growth plate there is substantial loss of S; this element being indicative for sulphate groups of glycosaminoglycans. This change seems to be an important factor conditioning the process of mineralization. Zn is found in higher concentration in mineralized tissues, both in embryonal and mature cartilage as well as in the bone, and this suggests that Zn is also involved in the mineralization process. The mineralization of rib cartilage exceeds that of embryonal bone, and the Ca/P ratio is higher in the former than in the hydroxyapatite of the latter. The method described is a useful analytical tool especially for such types of studies in which elements are not easily redistributed by freezing, cutting and drying; e.g. in investigations of mineral deposits.     

Copper binding in IscA inhibits iron‐sulphur cluster assembly in Escherichia coli

Among the iron‐sulphur cluster assembly proteins encoded by gene cluster iscSUA‐hscBA‐fdx in Escherichia coli, IscA has a unique and strong iron binding activity and can provide iron for iron‐sulphur cluster assembly in proteins in vitro. Deletion of IscA and its paralogue SufA results in an E. coli mutant that fails to assemble [4Fe‐4S] clusters in proteins under aerobic conditions, suggesting that IscA has a crucial role for iron‐sulphur cluster biogenesis. Here we report that among the iron‐sulphur cluster assembly proteins, IscA also has a strong and specific binding activity for Cu(I) in vivo and in vitro. The Cu(I) centre in IscA is stable and resistant to oxidation under aerobic conditions. Mutation of the conserved cysteine residues that are essential for the iron binding in IscA abolishes the copper binding activity, indicating that copper and iron may share the same binding site in the protein. Additional studies reveal that copper can compete with iron for the metal binding site in IscA and effectively inhibits the IscA‐mediated [4Fe‐4S] cluster assembly in E. coli cells. The results suggest that copper may not only attack the [4Fe‐4S] clusters in dehydratases, but also block the [4Fe‐4S] cluster assembly in proteins by targeting IscA in cells.     

Cytosolic iron‐sulphur protein assembly is functionally conserved and essential in procyclic and bloodstream Trypanosoma brucei

Cytosolic and nuclear iron‐sulphur (Fe/S) proteins include essential components involved in protein translation, DNA synthesis and DNA repair. In yeast and human cells, assembly of their Fe/S cofactor is accomplished by the CIA (cytosolic iron‐sulphur protein assembly) machinery comprised of some 10 proteins. To investigate the extent of conservation of the CIA pathway, we examined its importance in the early‐branching eukaryote Trypanosoma brucei that encodes all known CIA factors. Upon RNAi‐mediated ablation of individual, early‐acting CIA proteins, no major defects were observed in both procyclic and bloodstream stages. In contrast, parallel depletion of two CIA components was lethal, and severely diminished cytosolic aconitase activity lending support for a direct role of the CIA proteins in cytosolic Fe/S protein biogenesis. In support of this conclusion, the T. brucei CIA proteins complemented the growth defects of their respective yeast CIA depletion mutants. Finally, the T. brucei CIA factor Tah18 was characterized as a flavoprotein, while its binding partner Dre2 functions as a Fe/S protein. Together, our results demonstrate the essential and conserved function of the CIA pathway in cytosolic Fe/S protein assembly in both developmental stages of this representative of supergroup Excavata.     

Studies on ultrastructural identification and distribution of protein-polysaccharide in cartilage matrix

Previous reports on the ultrastructure of cartilage matrix have described fibers, amorphous ground substance and, in some instances, dense matrix granules. The fibers are presumably collagen, but the nature of the granules is unknown. The primary purpose of this study has been to investigate the ultrastructure of cartilage matrix ih chick embryos with particular emphasis on the distribution and composition of these granules. In matrix of the zone of articular cartilage, mature collagen fibers can be seen but granules are not present. In matrix of all other zones of cartilage, fibers are smaller and granules are present. When the matrix of epiphyseal cartilage is compared to that of the zone of hypertrophic cells, fibers are similar but the granules in the latter zone are larger and more numerous. The granules in both zones were digested by hyaluronidase and positive to colloidal iron staining. Chemical analyses of cartilage from these zones indicate the hexosamine and radiosulfate content of the zone of hypertrophic cells to be higher than that of the zone of epiphyseal cartilage. The increased hexosamine was shown by column chromatography to be principally sulfated mucopolysaccharide, thereby indicating a direct correlation between size and number of granules and sulfated mucopolysaccharide content in the two zones. These data and the results of the electron microscopic histochemical studies are consistent with the concept that the granules in cartilage matrix contain acidic mucopolysaccharide.     

An interaction between frataxin and Isu1/Nfs1 that is crucial for Fe/S cluster synthesis on Isu1

Depletion of the mitochondrial matrix protein frataxin is the molecular cause of the neurodegenerative disease Friedreich ataxia. The function of frataxin is unclear, although recent studies have suggested a function of frataxin (yeast Yfh1) in iron/sulphur (Fe/S) protein biogenesis. Here, we show that Yfh1 specifically binds to the central Fe/S-cluster (ISC)-assembly complex, which is composed of the scaffold protein Isu1 and the cysteine desulphurase Nfs1. Association between Yfh1 and Isu1/Nfs1 was markedly increased by ferrous iron, but did not depend on ISCs on Isu1. Functional analyses in vivo showed an involvement of Yfh1 in de novo ISC synthesis on Isu1. Our data demonstrate a crucial function of Yfh1 in Fe/S protein biogenesis by defining its function in an early step of this essential process. The iron-dependent binding of Yfh1 to Isu1/Nfs1 suggests a role of frataxin/Yfh1 in iron loading of the Isu scaffold proteins.     

Leaf age-dependent differences in sulphur assimilation and allocation in poplar (Populus tremula x P. alba) leaves

35S-sulphate was flap-fed to poplar leaves of different leaf development stages - young developing, expanding, mature, and old mature poplar leaves. (35)S-sulphate was taken up independent of the leaf development stage. Whereas young development leaves did not export the (35)S taken up, export increased with increasing leaf development stage. Expanding leaves allocated the exported (35)S mainly into apical tree parts (73-87%) and only to a minor extent (13-27%) in basipetal direction. Neither lower trunk sections nor the roots were sinks for the exported (35)S. Expanding and developing leaves, but not the shoot apex, were the main sinks for the (35)S allocated in apical direction. In contrast, mature and old mature leaves exported the (35)S taken up mainly in basipetal direction (65-82%) with the roots constituting the main sinks. The (35)S allocated into apical tree parts was found in expanding and developing leaves, but only to a minor extent in the shoot apex. Apical allocated (35)S was identified as sulphate. Apparently the demand of young developing leaves for reduced sulphur was not fulfilled by mature leaves. Therefore, reduced sulphur for growth and development of young developing leaves must be supplied from other sources. In vitro activity of enzymes involved in assimilatory sulphate reduction was measured to investigate whether demand for reduced sulphur by young leaves is met by their own sulphate reduction. ATP sulphurylase and APS reductase activities were not significantly lower in developing than in mature leaves. Sulphite reductase and serine acetyltransferase activities were highest in developing leaves; O:-acetylserine (thiol) lyase activity was similar in all leaf developing stages. Apparently, young developing poplar leaves are able to produce their own reduced sulphur for growth and development. Whether other sources such as storage tissues and/or roots are involved in reduced sulphur supply to developing leaves remains to be elucidated.     

The association between content of the elements S,Cl, K,Fe, Cu,Zn and Br in normal and cirrhotic liver tissue from Danes and Greenlandic Inuit examined by dual hierarchical clustering analysis

ProjectMeta-analysis of previous studies evaluating associations between content of elements sulphur (S), chlorine (Cl), potassium (K), iron (Fe), copper (Cu), zinc (Zn) and bromine (Br) in normal and cirrhotic autopsy liver tissue samples.ProcedureNormal liver samples from 45 Greenlandic Inuit, median age 60 years and from 71 Danes, median age 61 years. Cirrhotic liver samples from 27 Danes, median age 71 years. Element content was measured using X-ray fluorescence spectrometry. Statistics: Dual hierarchical clustering analysis, creating a dual dendrogram, one clustering element contents according to calculated similarities, one clustering elements according to correlation coefficients between the element contents, both using Euclidian distance and Ward Procedure.ResultsOne dendrogram separated subjects in 7 clusters showing no differences in ethnicity, gender or age. The analysis discriminated between elements in normal and cirrhotic livers. The other dendrogram clustered elements in four clusters: sulphur and chlorine; copper and bromine; potassium and zinc; iron. There were significant correlations between the elements in normal liver samples: S was associated with Cl, K, Br and Zn; Cl with S and Br; K with S, Br and Zn; Cu with Br. Zn with S and K. Br with S, Cl, K and Cu. Fe did not show significant associations with any other element.ConclusionsIn contrast to simple statistical methods, which analyses content of elements separately one by one, dual hierarchical clustering analysis incorporates all elements at the same time and can be used to examine the linkage and interplay between multiple elements in tissue samples.     

Effect of hydration in metHb: Reversible changes monitored by ESR of iron

The dehydration of human and bovine methemoglobins was monitored using ESR spectroscopy of the iron signal. The interconversion of the Fe(III) signal between the high spin form (at g 6) in solution and low spin form (at g 2) was quantitatively studied as a function of hydration. The dehydration process leads also to a loss of paramagnetism resulting in the appearance of about 40% Fe(II) below 0.40 grH₂O/grHb. The remaining 60% of Fe(III) ESR signal is distributed as the residual high spin form (at g 6, 5%) and low spin form (hemichromes H and P, 55%). The formation of hemichrome P was explained as resulting from the coordination of the cysteine residue at β⁹³ with the iron atom which follows the rupture of the proximal histidine bond. Experiments with hemoglobins where the sulphur atom of cysteine β was blocked (N-ethylmaleimide) did not showed the hemichrome P, confirming the involvement of the sulphur atom. This implies that the dehydration process induces displacements and torsion of the F helix, drastically changing the iron coordination at proximal site. In agreement with this proposition the Fe(II) symmetry is pentacoordinated with the disrupted bond to the proximal histidine at fifth coordination. This is also supported by ESR experiments with nitrosyl complex at low hydrations. All conformational changes were reversibly modulated by hydration degree and partially by lyophilization rate. A one-cycle dehydration of bovine hemoglobin followed by solubilization shows 100% reversibility of hemichrome P. Increasing the number of cycles of dehydration-hydration reduces the reversibility degree. With three cycles a reversibility of 70%–75% is observed. The level of 0.40 grH₂O/grHb was the critical hydration for the molecules to return to aquo met form and correspond also to a minimal water content necessary to cover all protein surface as obtained from other techniques.     

Comparison of bioleaching behaviors of different compositional sphalerite using <Emphasis Type="Italic">Leptospirillum ferriphilum</Emphasis>, <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis> and <Emphasis Type="Italic">Acidithiobacillus caldus</Emphasis>

Two sphalerite samples with different iron/sulphur (Fe/S) ratios, Shuikousan ore (Fe/S 0.2) and Dachang ore (Fe/S 0.52), were processed using three microbial species, Leptospirillum ferriphilum, Acidithiobacillus ferrooxidans and Acidithiobacillus caldus. Following 20 days of bioleaching in shake flask cultures, a higher zinc (Zn) extraction (96%) was achieved with Shuikousan ore than with Dachange ore (72%). The extraction efficiency increased when elemental S was added to Dachang ore to attain the same Fe/S ratio as that for Shuikousan ore. Following the addition of S, the redox potential, pH and total dissolved Fe for Dachang ore demonstrated similar behaviors to those of Shuikousan ore. Acidithiobacillus caldus and L. ferriphilum became the dominant species during the bioleaching of sphalerite with a high Fe/S ratio. In contrast, the dominant species were A. ferrooxidans and A. caldus during the bioleaching of sphalerite with a low Fe/S ratio. These results show that the Fe/S ratio has a significant influence on the bioleaching behavior of sphalerite and the composition of the microbial community.     

Simultaneous iron, zinc, sulfur and phosphorus speciation analysis of barley grain tissues using SEC-ICP-MS and IP-ICP-MS

The increasing prevalence of iron (Fe) and zinc (Zn) deficiencies in human populations worldwide has stressed the need for more information about the distribution and chemical speciation of these elements in cereal products. In order to investigate these aspects, barley grains were fractionated into awns, embryo, bran and endosperm and analysed for Fe and Zn. Simultaneously, phosphorus (P) and sulfur (S) were determined since these elements are major constituents of phytic acid and proteins, respectively, compounds which are potentially involved in Fe and Zn binding. A novel analytical method was developed in which oxygen was added to the octopole reaction cell of the ICP-MS. This approach greatly improved the sensitivity of sulfur, measured as (48)SO(+). Simultaneously, Fe was measured as (72)FeO(+), P as (47)PO(+), and Zn as (66)Zn(+), enabling sensitive and simultaneous analysis of these four elements. The highest concentrations of Zn, Fe, S and P were found in the bran and embryo fractions. Further analysis of the embryo using SEC-ICP-MS revealed that the speciation of Fe and Zn differed. The majority of Fe co-eluted with P as a species with the apparent mass of 12.3 kDa, whereas the majority of Zn co-eluted with S as a 3 kDa species, devoid of any co-eluting P. Subsequent ion pairing chromatography of the Fe/P peak showed that phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate: IP(6)) was the main Fe binding ligand, with the stoichiometry Fe(4)(IP(6))(18). When incubating the embryo tissue with phytase, the enzyme responsible for degradation of phytic acid, the extraction efficiency of both Fe and P was doubled, whereas that of Zn and S was unaffected. Protein degradation on the other hand, using protease XIV, boosted the extraction of Zn and S, but not that of Fe and P. It is concluded that Fe and Zn have a different speciation in cereal grain tissues; Zn appears to be mainly bound to peptides, while Fe is mainly associated with phytic acid.     

A combined computational and experimental investigation of the [2Fe–2S] cluster in biotin synthase

Biotin synthase was the first example of what is now regarded as a distinctive enzyme class within the radical S-adenosylmethionine superfamily, the members of which use Fe/S clusters as the sulphur source in radical sulphur insertion reactions. The crystal structure showed that this enzyme contains a [2Fe–2S] cluster with a highly unusual arginine ligand, besides three normal cysteine ligands. However, the crystal structure is at such a low resolution that neither the exact coordination mode nor the role of this exceptional ligand has been elucidated yet, although it has been shown that it is not essential for enzyme activity. We have used quantum refinement of the crystal structure and combined quantum mechanical and molecular mechanical calculations to explore possible coordination modes and their influences on cluster properties. The investigations show that the protonation state of the arginine ligand has little influence on cluster geometry, so even a positively charged guanidinium moiety would be in close proximity to the iron atom. Nevertheless, the crystallised enzyme most probably contains a deprotonated (neutral) arginine coordinating via the NH group. Furthermore, the Fe···Fe distance seems to be independent of the coordination mode and is in perfect agreement with distances in other structurally characterised [2Fe–2S] clusters. The exceptionally large Fe···Fe distance found in the crystal structure could not be reproduced.     

Positive colloidal thorium dioxide as an electron microscopical contrasting agent for glycosaminoglycans, compared with ruthenium red and positive colloidal iron

In electron microscopy Thorotrast has been used as a specific contrasting agent for acid glycosaminoglycans. Because of its high atomic number, thorium (Z=90) gives good contrast in the electron microscope, but at present it is less frequently used for this purpose. We prepared a positive colloidal solution of ThO2 without stabilizers to compare its properties with those of ruthenium red and positive colloidal iron for contrasting fetal mouse epiphyseal cartilage. The results indicate that colloidal ThO2, which is easy to prepare in any laboratory, gives better results than ruthenium red and colloidal iron do in this kind of cartilage. Furthermore, as judged from data in the literature and obtained in our laboratory, it penetrates this tissue better than Thorotrast does, probably because of the absence of stabilizers.     

Solution structure of the bacterial frataxin ortholog, CyaY: mapping the iron binding sites

CyaY is the bacterial ortholog of frataxin, a small mitochondrial iron binding protein thought to be involved in iron sulphur cluster formation. Loss of frataxin function leads to the neurodegenerative disorder Friedreich's ataxia. We have solved the solution structure of CyaY and used the structural information to map iron binding onto the protein surface. Comparison of the behavior of wild-type CyaY with that of a mutant indicates that specific binding with a defined stoichiometry does not require aggregation and that the main binding site, which hosts both Fe(2+) and Fe(3+), occupies a highly anionic surface of the molecule. This function is conserved across species since the corresponding region of human frataxin is also able to bind iron, albeit with weaker affinity. The presence of secondary binding sites on CyaY, but not on frataxin, hints at a possible polymerization mechanism. We suggest mutations that may provide further insights into the frataxin function.     

Distribution of sulphur forms in soils from beech and spruce forests of Mont Lozère (France)

From a quantitative inventory of sulphur forms and sulphur budget, the relation between the distribution of the various sulphur forms and the sulphate fluxes in three soil profiles has been addressed. These profiles are located in two forested watersheds at Mont Lozère. One has been sampled in a beech forest and the other two in a spruce forest and in a harvested plot of this spruce forest, respectively. The mean annual input-output budgets showed a sulphur immobilization in the soil cover of the three plots. In the preserved spruce forest plot, because of larger dry depositions, the sulphur immobilization is much greater than in other plots and occurs essentially in the B horizons. In the other two profiles, the dominant immobilization occurs in the parent material.The total sulphur content is very high in the forest floor reaching 2065 g S g^-1 in the litter of one of the soils under spruce. In the organo-mineral horizons of soils under spruce, the total sulphur content decreases with depth and ranges from 310 to 520 g S g^-1 in the A horizons to 100–200 g S g^-1 in the parent material. In the profile under beech, the total sulphur content is lower except in the parent material. In all cases, the organic sulphur is the major part of sulphur often representing more than 90% of total sulphur. In organo-mineral soil horizons of the spruce forest, the part of the sulphateesters is more important than in the soil of the beech forest, probably related to the different nature of the microbial activity in the spruce forest. In contrast, the humification processes are more efficient in the soil under beech, which can be due to the greater input of organic sulphur by litterfall. It appears that the dominant organic sulphur form varies as a function of microbial ecology and sulphate flux. The maximum of the inorganic sulphate is located at the base of the B horizons in the soil of the spruce forest and in the parent material of the soil under beech. In these horizons, the high content of inorganic sulphate can be related to the higher amounts of amorphous Fe and Al phases.     

Positive colloidal thorium dioxide as an electron microscopical contrasting agent for glycosaminoglycans,compared with ruthenium red and positive colloidal iron

Summary In electron microscopy Thorotrast has been used as a specific contrasting agent for acid glycosaminoglycans. Because of its high atomic number, thorium (Z=90) gives good contrast in the electron microscope, but at present it is less frequently used for this purpose. We prepared a positive colloidal solution of ThO₂ without stabilizers to compare its properties with those of ruthenium red and positive colloidal iron for contrasting fetal mouse epiphyseal cartilage. The results indicate that colloidal ThO₂, which is easy to prepare in any laboratory, gives better results than ruthenium red and colloidal iron do in this kind of cartilage. Furthermore, as judged from data in the literature and obtained in our laboratory, it penetrates this tissue better than Thorotrast does, probably because of the absence of stabilizers.     

The concentration of manganese,iron, and strontium in hip joint bone obtained from patients undergoing hip replacement surgery

The aim of this study was to determine the concentrations of manganese (Mn), iron (Fe) and strontium (Sr) in the cartilage with adjacent compact bone and spongy bone collected from patients after total hip replacement surgery. In addition, we examined relations between the concentrations of the metals in the bone and selected environmental factors. The concentration of Fe was the highest while Mn concentration was the lowest. The concentrations of Fe in the spongy bone in patients from larger cities were higher than in those living in smaller towns and villages. Significant correlations were found between Fe and Mn concentrations in the cartilage with adjacent compact bone and in the spongy bone, and between Mn and Sr in the spongy bone. In general, Mn, Fe and Sr concentrations in the bones of patients from NW Poland were lower than in other Polish regions and Europe, especially in industrialized countries. In conclusion, it seems that in addition to routine monitoring of the abiotic environment, it is essential to monitor concentrations of heavy metals having a long-term impact in humans.     

蚯蚓和铁处理对苹果根铁营养影响

试验于2007～2009年在河北省永年县曹庄村和中国农业大学曲周实验站进行。在苹果树根际用不同价态的2500、5000、10000、20000mg/kg的铁处理玉米秸秆后接种蚯蚓,研究蚯蚓和铁对苹果根系生长、蚯蚓对铁的富集转移及根质外体铁的影响。结果表明:蚯蚓对铁有很大的富集量,在20000mg/kg(试验所用最高浓度)二价铁和三价铁处理的秸秆中可以成活并把秸秆转化为蚯蚓粪,促进根系生长,提高根的质外体铁含量,蚯蚓对二价铁的适应性高于三价铁。蚯蚓可将有机物料中的铁转移到果树根系内,5000mg/kg铁处理增加蚯蚓体内Fe2+含量和根质外体铁含量效果最好,蚯蚓、蚯蚓粪和根中的全铁含量随铁处理浓度的增加而增加。铁显著促进果树根系生长,没有用铁处理过的秸秆接种蚯蚓诱导的新根量明显少于用铁处理的,两种不同价态的铁都是以5000mg/kg的新根量最多。蚯蚓显著促进根系生长,没有接种蚯蚓的处理新根量显著少于接种蚯蚓的处理。     

大气CO2浓度和供氮水平对油菜中微量元素吸收及转运的影响

在温室大棚中模拟大气CO₂浓度升高（780 μmol·mol ^-1）,研究了抽薹期油菜各器官对钙、镁、硫、铁、锰、锌、钼、硼离子吸收与运输的影响.结果表明： 与自然CO₂浓度（对照）相比,高CO₂浓度不施氮条件下,茎的中、微量元素含量除锌增加外,其他均减少,施氮条件（0.2 g N·kg^-1土）下钙、硫、硼、锌增加,镁、锰、钼、铁减少;叶的中、微量元素两个氮水平下都表现为除钼含量增加外,其他均下降.CO₂浓度升高条件下,茎中钙和硫占中量元素总和的比值及硼和锌占微量元素总和的比值增加,镁、铁、锰、钼相应比值减少,两个氮水平下表现一致;CO₂浓度升高条件不施氮处理增加了钙在叶中的分配比例,而正常供氮处理则增加了镁的分配比例,两个氮水平下均促进了锰、锌、钼在叶中的分配比例.不施氮条件下,高CO₂浓度处理的运输系数S_Fe,_Mo和S_S,B高于自然CO₂浓度处理,而S_Mg,Fe、S_Mg,Mn和S_S,Fe低于自然CO₂浓度处理,表明CO₂浓度升高条件下油菜向上运输的钼和硫高于铁,硼高于硫,镁高于铁和锰;正常供氮条件下,高CO₂浓度处理的S_Mg,Fe、S_Mg,Mn、S_S,B高于自然CO₂浓度处理,而S_Ca,Mg、S_Fe,Mo、S_S,Fe相反,表明CO₂浓度升高条件下油菜向上运输的钙、铁和锰高于镁,硼高于硫,铁高于钼,硫高于铁.     

大气CO2浓度和供氮水平对油菜中微量元素吸收及转运的影响

在温室大棚中模拟大气CO₂浓度升高（780 μmol·mol ^-1）,研究了抽薹期油菜各器官对钙、镁、硫、铁、锰、锌、钼、硼离子吸收与运输的影响.结果表明： 与自然CO₂浓度（对照）相比,高CO₂浓度不施氮条件下,茎的中、微量元素含量除锌增加外,其他均减少,施氮条件（0.2 g N·kg^-1土）下钙、硫、硼、锌增加,镁、锰、钼、铁减少;叶的中、微量元素两个氮水平下都表现为除钼含量增加外,其他均下降.CO₂浓度升高条件下,茎中钙和硫占中量元素总和的比值及硼和锌占微量元素总和的比值增加,镁、铁、锰、钼相应比值减少,两个氮水平下表现一致;CO₂浓度升高条件不施氮处理增加了钙在叶中的分配比例,而正常供氮处理则增加了镁的分配比例,两个氮水平下均促进了锰、锌、钼在叶中的分配比例.不施氮条件下,高CO₂浓度处理的运输系数S_Fe,_Mo和S_S,B高于自然CO₂浓度处理,而S_Mg,Fe、S_Mg,Mn和S_S,Fe低于自然CO₂浓度处理,表明CO₂浓度升高条件下油菜向上运输的钼和硫高于铁,硼高于硫,镁高于铁和锰;正常供氮条件下,高CO₂浓度处理的S_Mg,Fe、S_Mg,Mn、S_S,B高于自然CO₂浓度处理,而S_Ca,Mg、S_Fe,Mo、S_S,Fe相反,表明CO₂浓度升高条件下油菜向上运输的钙、铁和锰高于镁,硼高于硫,铁高于钼,硫高于铁.