Iron and copper in plasma membranes of maize (Zea mays L.) roots investigated by proton induced X-ray emission

Summary Plasma membranes of maize (Zea mays L., cv. Sil Anjou 18) roots were isolated by aqueous two-phase partitioning. Multi elemental analysis by proton induced X-ray emission (PIXE) was used for the investigation of elemental composition of plasma membranes. Fe, Cu, and Zn as well as P, S, and Ca were identified. We did not find significant amounts of V, Mn, Se, Mo, or W.Abbreviations EDTA ethylenediaminetetraacetic acid - HCF III hexacyanoferrate III (ferricyanide, K₃[FeCN₆]) - Hepes 2-[4-(2-hydroxyethyl)-1-piperazine]-ethanesulfonic acid - PIXE proton induced X-ray emission (proton microprobe) - STA siliciotungstic acid - Tris tris (hydroxymethyl)aminomethane     

Why do melanin ornaments signal individual quality? Insights from metal element analysis of barn owl feathers

Melanin-based variation in colour patterns is under strong genetic control and not, or weakly, sensitive to the environment and body condition. Current signalling theory predicts that such traits may not signal honestly phenotypic quality because their production does not entail a significant fitness cost. However, recent studies revealed that in several bird species melanin-based traits covary with phenotypic attributes. In a first move to understand whether such covariations have a physiological basis, we quantified concentrations of five chemical elements in two pigmented plumage traits in the barn owl (Tyto alba). This bird shows continuous variation from immaculate to heavily marked with black spots (plumage spottiness) and from dark reddish-brown to white (plumage coloration), two traits that signal various aspects of individual quality. These two traits are sexually dimorphic with females being spottier and darker coloured than males. We found an enhancement in calcium and zinc concentration within black spots compared with the unspotted feather parts. The degree to which birds were spotted was positively correlated with calcium concentration within spots, whereas the unspotted feather parts of darker reddish-brown birds were more concentrated in zinc. This suggests that two different pigments are responsible for plumage spottiness and plumage coloration. We discuss the implications of our results in light of recent experimental field studies showing that female spottiness signals offspring humoral response towards an artificially administrated antigen, parasite resistance and fluctuating asymmetry of wing feathers.An erratum to this article can be found at     

Penetration by Artificial Electron Acceptors of the Plasma Membrane-Bound Redox System into Intact Zea mays L. Roots Investigated by Proton-Induced X-Ray Emission

Proton-induced x-ray emission was used to investigate the penetration of compounds of the membrane-impermeant electron acceptors hexabromoiridate IV, hexachloroiridate IV, and hexacyanoferrate III into corn (Zea mays L.) roots. Maps of the heavy element distribution in cross-sections of fixed, epoxy-embedded roots showed for hexabromoiridate IV small amounts of Br in samples treated for 24 h with concentrations normally used in physiological experiments (0.02 mM). After treatment with high concentrations (0.8 mM) of these complexes, Fe and Ir as well as Br were found in root cross-sections. In samples taken at a distance of 5 mm behind the root tip, we found an even distribution of Fe, Ir, and Br over the whole cross-section. In samples taken 15 mm behind the root tip, about 99% of both Br and Ir was confined to the rhizodermal cell layer. The distribution did not change with the complex used. These data are consistent with the view that apoplastic diffusion of the electron acceptors was blocked by the hypodermal Casparian band.     

Correlations between melanin pigmentation and element concentration in feathers of White-tailed Eagles (Haliaeetus albicilla)

Summary The element concentration of moult feathers of White-tailed Eagles was investigated. Using the 2- MeV Hamburg proton microprobe we tried to differentiate between elements incorporated into the feather via the food chain and those which are deposited externally onto the feather vane. Regarding incorporated elements, special attention has been given to a possible correlation between element concentration and feather pigmentation. Concerning the elements detected in this work (S, K, Ca, Ti, Mn, Fe, Cu, Zn, Hg, Pb), calcium, manganese and zinc show a considerable enhancement within the pigmented feather as compared with pigment-free feather sections. On the other hand, no differences were found in concentrations for sulfur, titanium, iron, copper, mercury and lead. Our findings therefore imply a special enrichment of Ca, Mn and Zn within melanin, the source of the feather's pigmentation. The possible role of these elements with regard to melanin formation is discussed.

---

Melaninpigmentation und Elementkonzentration in Federn des Seeadlers (Haliaeetus albicilla)

Zusammenfassung Es wurden die Elementkonzentrationen in Mauserfedern von Seeadlern untersucht. Mit Hilfe der Hamburger 2-MeV-Protonenmikrosonde, die die Analyse von Probendetails im Mikrometerbereich ermöglicht, versuchen wir zwischen Elementen zu unterscheiden, die vom Adler mit der Nahrung inkorporiert, verstoffwechselt und während der Mauser in die Feder eingelagert wurden und solchen, die während der etwa einjährigen Verweilzeit der Feder im Gefieder extern aus der Atmosphäre aufgelagert wurden.Im Hinblick auf die eingelagerten Elemente untersuchen wir mögliche Zusammenhänge zwischen der Elementkonzentration und der Federpigmentierung. Von den nachgewiesenen Elementen (Schwefel, Kalium, Calcium, Titan, Mangan, Eisen, Kupfer, Zink, Quecksilber und Blei) zeigen Calcium, Mangan und Zink eine erhebliche Anreicherung in der pigmentierten Feder im Vergleich zu pigmentfreien Federausschnitten. Dagegen wurden keine signifikanten Unterschiede der Elementkonzentrationen von Schwefel, Titan, Eisen, Kupfer, Quecksilber und Blei festgestellt. Die gefundenen Ergebnisse bedeuten eine erhebliche Anreicherung von Calcium, Mangan und Zink im Melanin, das für die Federpigmentierung verantwortlich ist. Die mögliche Funktion dieser Elemente im Hinblick auf die Melaninbildung wird diskutiert.

     

Sulfide silver amplification of ferritin iron cores in blood and bone marrow cells. Methods, adaptations to microphysical analyses, and the impact of advanced iron overload

A short exposure of cell suspensions to gaseous hydrogen sulfide, appropriate fixations, and subsequent physical development of silver shells around sulfidated insoluble metals were used to amplify ferritin iron cores in blood and bone marrow cells. The methods described are suitable for both light microscopy and transmission electron microscopy. These techniques made it possible to visualize Prussian Blue stainable ferritin and haemosiderin, as well as a large variety of isoferritin iron and other smaller particles beyond the sensitivity of Prussian Blue staining. Admixtures of sulfidatible zinc and traces of other heavy metals had to be taken into consideration. For further research, adaptations of sulfide silver staining to microphysical analyses were developed. However, conventional energy dispersive X-ray analysis was not sensitive enough to signalize the presence of Fe in sulfide silver amplified iron cores of a single or a few ferritin molecule(s). Proton-induced X-ray emission was used to measure Fe and Zn down to 1 fg/single cell in unstained or sulfide silver stained smears on thin foils. However, multielement analysis of homogeneous cell concentrates was much easier to perform and far more sensitive. In advanced iron overload, highly increased sulfide silver staining was found in peripheral blood cells including lymphocytes, monocytes, eosinophils, basophils, and--in extreme cases--also in neutrophils and platelets.     

ElaC encodes a novel binuclear zinc phosphodiesterase

ElaC is a widespread gene found in eubacteria, archaebacteria, and mammals with a highly conserved sequence. Two human ElaC variants were recently associated with cancer (Tavtigian, S. V., Simard, J., Teng, D. H., Abtin, V., Baumgard, M., Beck, A., Camp, N. J., Carillo, A. R., Chen, Y., Dayananth, P., Desrochers, M., Dumont, M., Farnham, J. M., Frank, D., Frye, C., Ghaffari, S., Gupte, J. S., Hu, R., Iliev, D., Janecki, T., Kort, E. N., Laity, K. E., Leavitt, A., Leblanc, G., McArthur-Morrison, J., Pederson, A., Penn, B., Peterson, K. T., Reid, J. E., Richards, S., Schroeder, M., Smith, R., Snyder, S. C., Swedlund, B., Swensen, J., Thomas, A., Tranchant, M., Woodland, A. M., Labrie, F., Skolnick, M. H., Neuhausen, S., Rommens, J., and Cannon-Albright, L. A. (2001) Nat. Genet. 27, 172-180; Yanaihara, N., Kohno, T., Takakura, S., Takei, K., Otsuka, A., Sunaga, N., Takahashi, M., Yamazaki, M., Tashiro, H., Fukuzumi, Y., Fujimori, Y., Hagiwara, K., Tanaka, T., and Yokota, J. (2001) Genomics 72, 169-179). Analysis of the primary sequence indicates homology to an arylsulfatase and predicts a metallo-beta-lactamase fold. At present, no ElaC gene product has been investigated. We cloned the Escherichia coli ElaC gene and purified the recombinant gene product. An enzymatic analysis showed that ElaC does not encode an arylsulfatase but rather encodes a phosphodiesterase that hydrolyzes bis(p-nitrophenyl)phosphate with a k(cat) of 59 s(-1) and K' of 4 mm. Kinetic analysis of the dimeric enzyme revealed positive cooperativity for the substrate bis(p-nitrophenyl)phosphate with a Hill coefficient of 1.6, whereas hydrolysis of the substrate thymidine-5'-p-nitrophenyl phosphate followed Michaelis-Menten kinetics. Furthermore, the enzyme is capable of binding two zinc or two iron ions. However, it displays phosphodiesterase activity only in the zinc form. The metal environment characterized by zinc K-edge x-ray absorption spectroscopy was modeled with two histidine residues, one carboxylate group, and 1.5 oxygen atoms. This corresponds to the coordination found in other metallo-beta-lactamase domain proteins. Phosphodiesterase activity is strongly dependent on the presence of zinc. These results identify the currently unassigned gene product ElaC to be a novel binuclear zinc phosphodiesterase.     

Quecksilber in Federn des Sperbers(Accipiter nisus) aus dem Erzgebirge

Zusammenfassung In der vorliegenden Arbeit wird der Quecksilbergehalt von 48 Mauserfedern (Hand- und Armschwingen) des Sperbers aus dem Erzgebirge (Freistaat Sachsen, BRD) untersucht. Die Federn stammen von 37 Weibchen und wurden zwischen 1980 und 1998 gesammelt. Zum Vergleich dienen fünf Federproben von Museumspräparaten, die vor 1930 auf dem Gebiet des Freistaates Sachsen gesammelt wurden. Die Federproben wurden mit der Hamburger Protonenmikrosonde analysiert. Die Quecksilbergehalte der Mauserfedern des selben Vogels können relativ große Unterschiede aufweisen (n=3 ). Eine deutliche Reduktion der Hg-Konzentration mit fortschreitender Handschwingenmauser zeigte nur ein Weibchen. Als Vergleichswert für eine Hg-Grundbelastung vor 1930 wurden 2,7 ppm Hg (n=5) ermittelt. Die in den 1980er Jahren stark angestiegenen Konzentrationswerte (x_G=22,6 ppm, n=25) fielen 1997/98 auf 4,0 ppm Hg (n=10) ab, was auf eine Verringerung des anthropogenen Quecksilbereintrages in die Umwelt nach 1990 schließen lässt. Regionale Kontaminationsunterschiede zeichneten sich zwischen dem Gebiet der Großstadt Chemnitz und dem höher belasteten Umland ab (1980–1990). Die höchsten Quecksilbergehalte wurden in Sperberfedern aus dem Bereich Niederwiesa-Flöha-Falkennau festgestellt (Landkreis Freiberg).

---

Mercury in the feathers of the Sparrowhawk(Accipiter nisus) from the Erz Mountains

Summary The present paper examines the concentration of mercury in 48 moult-feathers (primaries and secondaries) of the Sparrowhawk from the Erzgebirge region (province of Saxony, Germany). The feathers were collected from 37 females between 1980 and 1998. Five feather-samples of museum-preparations, collected in the area of the federal state of Sachsen before 1930, serve to provide a comparison with times with a low Hg use. All samples were analysed by the Hamburg proton micro-probe. The mercury contents of the moultfeathers from the same bird showed relatively great differences (n=3 ). Only one female showed a clear reduction of the Hg concentration with the progressive moult of the primaries. The feather-samples, collected before 1930, contained 2.7 ppm mercury (n=5). The concentration increased in the eighties up to 22.6 ppm (n=25) and decreased to 4.0 ppm in 1997/98. There was a reduction of the amount of mercury entering the environment as a result of human activities after 1990. Regional deviations of contamination were characteristic between the area of the city Chemnitz and the highly contaminated surroundings (1980–1990). The highest mercury concentration was established in the moult-feathers from the region of Niederwiesa-Flöha-Falkenau (county Freiberg, 1990).