Recent insights into iron homeostasis and their application in graminaceous crops

Higher plants utilize various mechanisms to maintain iron homeostasis. To acquire sparingly soluble iron from the rhizosphere, graminaceous plants synthesize natural iron (III) chelators known as mugineic acid family phytosiderophores (MAs). Recent research has uncovered various genes involved in iron uptake and translocation, as well as factors regulating the expression of these genes, especially in rice. Manipulation of these molecular components is used to produce transgenic crops with enhanced tolerance to iron deficiency, or with a high seed iron content. Since iron homeostasis is closely linked to that of other mineral elements, an understanding of this phenomenon will serve as the basis for the production of crops with low concentrations of toxic metals and transgenic plants for phytoremediation.     

Professor Dr. Justus Mühlenpfordt zum 60. Geburtstag

An efficient potential for radiation research has been developed at the Central Institute of Isotope and Radiation Research in Leipzig since 1969. 2Iany problems in the field of basic and applied research of radiation chemistry and biology have been studied. Ten gamma plants and two electron accelerators have been designed and established for scientific, industrial and agricultural application.     

Carbon and oxygen isotope working standards from C3 and C4 photosynthates

A preparation of organic working standards for the online measurement of ¹³C/¹²C and ¹⁸O/¹⁶O ratios in biological material is presented. The organic working standards are simple and inexpensive C₃ and C₄ carbohydrates (sugars or cellulose) from distinct geographic origin, including white sugar, toilet and XEROX papers from Switzerland, maize from Ivory Coast, cane sugar from Brazil, papyrus from Egypt, and the core of the stem of a Cyperus papyrus plant from Kenya. These photosynthetic products were compared with International Atomic Energy standards CH-3 and CH-6 and other calibration materials. The presented working standards cover a 15 ‰ range of ¹³C/¹²C ratios and 9 ‰ for ¹⁸O/¹⁶O, with a precision<±0.2 ‰ for n>10.     

Использование изотопа N15 в изученпи усвояемости азотньіх минеральньіх удобрений

The effect of contamination of a cyanide, phosphate-buffered gold-plating bath with iron, cobalt, or nickel on the codeposition of these metals with gold, was investigated using ⁵⁹Fe, ⁵⁸Co and ⁶³Ni. It was shown that cobalt and nickel were practically not codeposited in gold if present in the solution in amounts up to 1000 or 2000 mg/dm³ respectively. Iron deposited in high amounts (up to 18%) depending on its concentration and the cathode current density. The diminishing in current efficiency of the plating process is proposed as an early signal of the contamination of gold deposit with iron.     

Leaf allocation patterns and 13C and 15N natural abundances of tropical lianas (Passiflora sp.) as dependent on external climbing support

The transformation from self-supporting lianas to host-supported climbing lianas is related to re-allocation of biomass and nutrients among plant organs. Therefore, first, variations in leaf mass per area (LMA), leaf carbon and nitrogen allocation and ¹³C and ¹⁵N natural abundances were analysed among three tropical Passiflora species (P. edulis, P. ligularis, and P. tripartita) in a greenhouse study. Second, the influence of a climbing support was considered for each species and parameter. P. ligularis leaves were most enriched in ¹³C in both treatments when compared with the other two species. This enrichment was caused by a high LMA, which is related to a high internal resistance to CO₂ diffusion. For P. edulis and P. tripartita, δ¹³C was additionally increasing with nitrogen content per area. Generally, there were no differences when considering carbon and nitrogen allocation to leaves of host-supported and self-supporting lianas. The only hints towards increased investment into leaves after the transition from self-supporting to host-supported stages could be seen by a trend to increased leaf areas and masses. δ¹³C values of supported P. edulis or P. tripartita plants were significantly increasing faster than those of non-supported plants once the interactions of leaf mass or nitrogen content per area were accounted for. Hence, the offer of a climbing support had only a minor impact on δ¹³C or δ¹⁵N values in vitro, but this could be different with increasing age of lianas in vivo.     

Assessing the subsequent effect of nitrogen released from tobacco-waste on maize crop using a 15N isotope technique

The investigation of the residual effect of nitrogen (N) released from tobacco-waste (TW) using isotope techniques will provide valuable data for sustainable organic farming. For this aim, a pot experiment was conducted using the ¹⁵N isotope technique. The experiment was based on a completely randomised design with four replications and was conducted on a calcareous ustochrepts soil. TW at levels of 0, 10, 20, 30 and 40 t ha^?1 and N fertiliser as (NH₄)₂SO₄ at levels of 0, 20, 40, 60 and 80 kg N ha^?1 were used for the Bezostaja-1 wheat variety. Concerning mineral N fertilisation with 20 and 80 kg N ha^?1, additional treatments with ¹⁵N-labelled (NH₄)₂SO₂ (10 at.% exc.) have been applied. Following harvesting wheat plants, the Pioneer 3377 maize variety was used to see the residual effect of TW. After harvesting, dry matter yields were recorded and total N concentrations were determined. ¹⁵N determinations and calculations were also made for ¹⁵N treatments separately. TW had a significant residual effect on the growth of corn plant under the pot condition. Increasing rates of TW significantly increased the dry matter yield of corn plant following wheat from 3.31 t ha^?1 (at control) to 7.89 t ha^?1 (at the TW treatment of 40 t ha^?1). The ¹⁵N values derived from the ¹⁵N fertiliser decreased with increasing TW application. The average values of N derived from N fertiliser (Ndff) varied from 2.14 to 3.09% at the rates of 20 and 80 kg N ha^?1, respectively. However, N derived from TW (Ndftw) significantly increased from 16.93 to 24.59% (at 20 kg N ha^?1), and it also increased from 23.06 to 28.15% (at 80 kg N ha^?1) with increasing TW applications from 20 to 40 t ha^?1, respectively.     

Beispiele für die Anwendung der 15N-Tracertechnik in der Düngungsforschung mit emissionsspektrometrischen Analysenverfahren (NOI-5; Isonitromat-5200)

Es werden Varianten der Probenchemie für ¹⁵N-Bilanzexperimente in der Düngungsforschung vorgestellt, die den Erfordernissen des Isonitromat-5200 und des NOI-5 angepaßt sind. Die skizzierten Methoden umfassen die destillative Präparation markierter N-Mengen (0,1–1 mg) aus Bodenextrakten, verbunden mil einem Zvsatz unmatkierter N-Mengen bei der Titration sowie eine für den Routinebetrieb geeignete N-Bestimmung in nicht angereicherten Pflanzenaufschlüssen mit dem Isonitromat-5200 als ¹⁵N-Verdünnungsanalyse. Weiterhin werden einfache apparative Varianten zur Bestimmung von sog. Gasförmigen Düngersticksloffverlusten durch Denitrifizierung in gasdichten Kammern dargestellt.

Durch ¹⁵N-Analyse von Luftproben über ¹⁵N-angereicherten natürlichen Bodenmonolithen mit dem NOI-5 können unmittelbar die vom Dünger freigesetzten N₂ und N₂O-Mengen bestimmt werden. Bei Spezialversuchen in stickstofffreier Neon(He)-Atmosphäre können gebildete N₂-, NO- und N₂O-Spuren (um 1 Vol. %)nach gaschromatographischer Trennung (auf Perapak-Q) individuell am NOI-5 gemessen werden. Unter Verwendung von CO₂-Trägergas werden die N-Komponenten in einem Azotometer isoliert und mit Hilfe eines Dosierhahnes, dessen Volumen den geforderten Gasdruck garantiert, in Entladungsrohre überführt.     

Originalarbeiten 133m Xe zur Markierung von Gasphasen bei technischen Tracerexperimenten

Bei technischen Tracerexperimenten bereitet die Markierung von Gasphasen Schwierigkeiten, wenn man auf Außenwandmessungen angewiesen ist, da die Auswahl an geeigneten Radionukliden bzw. radioaktiv markierten Verbindungen dann sehr beschrānkt ist. Eine gute Ergänzung des Radionuklidangebotes für den genannten Zweck bietet ^133mXe, Halbwertszeit 2,3 d, E_γ = 0,23 MeV (16%). ^133mXe erhält man mit guten Ausbeuten bei einer Reaktoraktivierung von natürlichem Xenon. Die Sälligungsaktivität fär ^133mXe beträgt bei einem Fluß von 5,0 μ 10¹³ n/cm²s 48,5 mCi/cm³ Xenon (unter Normalbedingungen). An Veweilzeitmessungen von Gasphasen in technischen Anlagen werden die Einsatzmöglichkeiten des ^133mXe dargestellt.     

Phytochemical Constituents,Antioxidant Activity,and Toxicity Assessment of the Aerial Part Extracts from the Infraspecific Taxa of Matthiola fruticulosa (Brassicaceae) Endemic to Sicily

In a project designed to investigate the specific and infraspecific taxa of Matthiola endemic to Sicily (Italy) as new potential sources of bioactive compounds in this work, the infraspecific taxa of Matthiola fruticulosa were studied, namely, subsp. fruticulosa and subsp. coronopifolia. HPLC–PDA/ESI–MS and SPME–GC/MS analyses of hydroalcoholic extracts obtained from the aerial parts of the two subspecies led to the detection of 51 phenolics and 61 volatile components, highlighting a quite different qualitative–quantitative profile. The antioxidant properties of the extracts were explored through in vitro methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), reducing power and Fe²⁺ chelating activity assays. The results of the antioxidant tests showed that the extracts possess a different antioxidant ability: particularly, the extract of M. fruticulosa subsp. fruticulosa exhibited higher radical scavenging activity than that of subsp. coronopifolia (IC₅₀ = 1.25 ± 0.02 mg/mL and 2.86 ± 0.05 mg/mL), which in turn displayed better chelating properties (IC₅₀ = 1.49 ± 0.01 mg/mL and 0.63 ± 0.01 mg/mL). Lastly, Artemia salina lethality bioassay was performed for toxicity assessment. The results of the bioassay showed lack of toxicity against brine shrimp larvae for both extracts. The data presented indicate the infraspecific taxa of M. fruticulosa as new and safe sources of antioxidant compounds.     

Screening of medicinal plants traditionally used in Peruvian Amazon for in vitro antioxidant and anticancer potential

Plants mentioned in this study have numerous records in traditional Peruvian medicine being used in treatment of cancer and other diseases likely to be associated with oxidative stress. Amongst the eight plant species tested, only Dysphania ambrosioides exhibited combinatory antioxidant and anti-proliferative effect on a broad spectrum of cancer cells (DPPH and ORAC values = 80.6 and 687.3 μg TE/mg extract, respectively; IC₅₀ against Caco-2, HT-29 and Hep-G2 = 129.2, 69.9 and 130.6, respectively). Alkaloids and phenolic compounds might significantly contribute to anticancer/antioxidant activity of this plant. The results justify the traditional medicinal use of this plant. Our findings further suggest that D. ambrosioides might serve as a prospective material for further development of novel plant-based antioxidant and/or anti-proliferative agents. Detailed analysis of chemical composition together with toxicology assessments and in vivo antioxidant/anti-proliferative activity of this plant should be carried out in order to verify its potential practical use.