[Olfactory dysfunctions are substantially more frequent than they are complained]. / Riechstörungen sind wesentlich häufiger als sie beklagt werden.

BACKGROUND: Probably less than 0.1% of the population of the western world might seek medical advice because of olfactory or gustatory dysfunctions. In contrast, it can be assumed that the prevalence of olfactory dysfunction is about 20%. The estimated number of unreported cases must be high. Related to the population of the city of Jena it shall be investigated, how many patients visit a doctor because of an olfactory dysfunction. MATERIALS AND METHODS: Data of all patients, who underwent olfactory testing at the ENT department of the university hospital in Jena between 1998 and 2004 and had their main residence in Jena were identified. Based on subjective self-assessment of smelling function and on different olfactory test procedures subjectively smelling-disturbed people and objectively smelling-disturbed people were separated. Calculation of the prevalence was based on data from the registration office of Jena. RESULTS: Related to the total population of Jena 0.23% of Jena's inhabitants underwent olfactory testing procedure between 1998 and 2004. 0.08% complained about subjective olfactory dysfunction. Only 0.05% were really suffering from olfactory dysfunction confirmed by olfactory testing. DISCUSSION: Only a small percentage of Jena's inhabitants visit a doctor because of olfactory dysfunction. Therefore, in Jena no other health behaviour concerning olfactory disorders can be observed than in other industrial countries. The estimated number of unreported cases of olfactory disturbances is higher than supposed. The medical professional societies should to an increased education of medical doctors and patients regarding symptoms, refined diagnostics, outlook and risen therapeutical chances of olfactory disorders.

Responses of Picea, Pinus and Pseudotsuga roots to heterogeneous nutrient distribution in soil.

The spatial distribution of plant-available mineral nutrients in forest soils is often highly heterogeneous. To test the hypothesis that local nutrient enrichment of soil leads to increased root proliferation in the nutrient-rich soil zone, we studied the effects of nutrient enrichment on the growth and nutrient concentrations of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) roots. Three-year-old seedlings were grown for 9 months in split-root containers filled with nutrient-poor forest mineral soil, with one side supplemented with additional mineral nutrients. Root dry weight and root length in Scots pine and Norway spruce were increased in the nutrient-supplemented soil compared with the nonsupplemented side, whereas root growth in Douglas-fir was unaffected by nutrient enrichment. Of the three species examined, Norway spruce exhibited the highest root and shoot growth and the highest nutrient demand. Specific root length (m g(-1)) and the number of root tips per unit root length were not affected by local nutrient addition in any of the species. Despite increased root growth in Norway spruce and Scots pine in nutrient-supplemented soil, their root systems contained similar nutrient concentrations on both sides of the split-root container. Thus, coniferous trees may respond to local nutrient supply by increased root proliferation, but the response varies depending on the species, and may only occur when trees are nutrient deficient. As a response to local nutrient enrichment, increases in root dry matter or root length may be better indicators of pre-existing nutrient deficiencies in conifers than increases in root nutrient concentrations.

The Role of Ligand Exchange in the Uptake of Iron from Microbial Siderophores by Gramineous Plants.

The siderophore rhizoferrin, produced by the fungus Rhizopus arrhizus, was previously found to be as an efficient Fe source as Fe-ethylenediamine-di(o-hydroxphenylacetic acid) to strategy I plants. The role of this microbial siderophore in Fe uptake by strategy II plants is the focus of this research. Fe-rhizoferrin was found to be an efficient Fe source for barley (Hordeum vulgare L.) and corn (Zea mays L.). The mechanisms by which these Gramineae utilize Fe from Fe-rhizoferrin and from other chelators were studied. Fe uptake from 59Fe-rhizoferrin, 59Fe-ferrioxamine B, 59Fe-ethylenediaminetetraacetic acid, and 59Fe-2[prime]-deoxymugineic acid by barley plants grown in nutrient solution at pH 6.0 was examined during periods of high (morning) and low (evening) phytosiderophore release. Uptake and translocation rates from Fe chelates paralleled the diurnal rhythm of phytosiderophore release. In corn, however, similar uptake and translocation rates were observed both in the morning and in the evening. A constant rate of the phytosiderophore's release during 14 h of light was found in the corn cv Alice. The results presented support the hypothesis that Fe from Fe-rhizoferrin is taken up by strategy II plants via an indirect mechanism that involves ligand exchange between the ferrated microbial siderophore and phytosiderophores, which are then taken up by the plant. This hypothesis was verified by in vitro ligand-exchange experiments.

Roots of Iron-Efficient Maize also Absorb Phytosiderophore-Chelated Zinc.

To investigate the recognition of Zn-phytosiderophores by the putative Fe-phytosiderophore transporter in maize (Zea mays L.) roots, short-term uptake of 65Zn-labeled phytosiderophores was compared in the Fe-efficient maize cultivar Alice and the maize mutant ys1 carrying a defect in Fe-phytosiderophore uptake. In ys1, uptake and translocation rates of Zn from Zn-phytosiderophores were one-half of those in Alice, but no genotypical difference was found in Zn uptake and translocation from other Zn-binding forms. In ys1 and in tendency also in Alice, Zn uptake decreased with increasing stability constant of the chelate in the order: ZnSO4 [greater than or equal to] Zn-desferrioxamine > Zn-phytosiderophores > Zn-EDTA. Adding a 500-fold excess of free phytosiderophores over Zn to the uptake solution depressed Zn uptake in ys1 almost completely. In uptake studies with double-labeled 65Zn-14C-phytosiderophores, ys1 absorbed the phytosiderophore at similar rates when supplied as a Zn-chelate or the free ligand. By contrast, in Alice 14C-phytosiderophore uptake from the Zn-chelate was 2.8-fold higher than from the free ligand, suggesting that Alice absorbed the complete Zn-phytosiderophore complex via the putative plasma membrane transporter for Fe-phytosiderophores. We propose two pathways for the uptake of Zn from Zn-phytosiderophores in grasses, one via the transport of the free Zn cation and the other via the uptake of nondissociated Zn-phytosiderophores.

Effect of mineral nutritional status on shoot-root partitioning of photoassimilates and cycling of mineral nutrients.

Mineral nutrients taken up by the roots are, as a rule, transported in the xylem to the shoot, and photoassimilates transported in the phloem to the roots. According to the Thornley model of photosynthate partitioning, nutrient deficiencies should favour photosynthate partitioning to the roots. Examples are cited to show that this preferential partitioning is dependent on phloem mobility and hence on nutrient cycling from shoot to roots. Thus, root growth is enhanced under nitrogen and phosphorus deficiencies, but not under deficiencies of nutrients of low mobility in the phloem, such as calcium and boron. Enhanced root growth under nutrient deficiency relies on the import of both photosynthates and mineral nutrients. Cycling of mineral nutrients serves a number of other functions. These include the root supply of nutrients assimilated in the shoot (nitrate and sulphate reduction), maintenance of cation-anion balance in the shoot, providing an additional driving force for solute volume flow in the phloem and xylem, and acting as a shoot signal to convey nutrient demand to the root. Cycling of certain mineral nutrients through source leaves has a considerable impact on photosynthate export as demonstrated in impaired export under magnesium, potassium, or zinc deficiencies. Mineral nutrient deficiency can, therefore, affect photosynthate partitioning either directly via phloem loading and transport or indirectly by depressing sink demand.

Transfer of PCDD/PCDF from contaminated soils into carrots, lettuce and peas.

In a field experiment, the PCDD/PCDF transfer pathways from soil into carrots, lettuce and peas has been investigated. PCDD/PCDF contamination levels in soil varied between 5 ng I-TEq/kg on the control plot and 56 ng I-TEq/kg on the contaminated plot. PCDD/PCDF levels in carrots were threefold higher in the contaminated plot than in the control plot, which was a result of a tenfold increase in the PCDD/PCDF levels of the peel. PCDD/PCDF levels in lettuce and peas were not higher when grown on the contaminated plot and were much lower than in carrots, which indicates that the PCDD/PCDF in lettuce and peas from both plots are of atmospheric origin.

Iron Inefficiency in Maize Mutant ys1 (Zea mays L. cv Yellow-Stripe) Is Caused by a Defect in Uptake of Iron Phytosiderophores.

To determine the Fe inefficiency factors in the maize mutant ys1 (Zea mays L. cv Yellow Stripe), root exudates of Fe-inefficient ys1 and of two Fe-efficient maize cultivars (Alice, WF9) were collected in axenic nutrient solution cultures. Analysis by thin-layer chromatography and high-performance liquid chromatography revealed that under Fe deficiency ys1 released the phytosiderophore 2[prime]-deoxymugineic acid (DMA) in quantities similar to those of Alice and WF9. Under nonaxenic conditions, DMA released by plants of all three cultivars was rapidly decomposed by microorganisms in the nutrient solution. Uptake experiments with 59Fe-labeled DMA, purified from root exudates of either Fe-deficient Alice or ys1 plants, showed up to 20 times lower uptake and translocation of 59Fe in ys1 than in Alice or WF9 plants. The presence of microorganisms during preculture and short-term uptake experiments had no significant effect on uptake and translocation rates of 59Fe in Alice and ys1 plants. We conclude that Fe inefficiency in the maize mutant ys1 is the result of a defect in the uptake system for Fe-phytosiderophores.

Short-term effects of rhizosphere microorganisms on fe uptake from microbial siderophores by maize and oat.

Effects of rhizosphere microorganisms on Fe uptake by oat (Avena sativa) and maize (Zea mays) were studied in short-term (10 h) nutrient solution experiments. Fe was supplied either as microbial siderophores (pseudobactin [PSB] or ferrioxamine B [FOB]) or as phytosiderophores obtained as root exudates from barley (epi-3-hydroxy-mugineic acid [HMA]) under varied population densities of rhizosphere microorganisms (axenic, uninoculated, or inoculated with different microorganism cultures). When maize was grown under axenic conditions and supplied with FeHMA, Fe uptake rates were 100 to 300 times higher compared to those in plants supplied with Fe siderophores. Fe from both sources was taken up without the involvement of an extracellular reduction process. The supply of FeHMA enhanced both uptake rate and translocation rate to the shoot (more than 60% of the total uptake). However, increased density of microorganisms resulted in a decrease in Fe uptake rate (up to 65%), presumably due to microbial degradation of the FeHMA. In contrast, when FeFOB or FePSB was used as the Fe source, increased population density of microorganisms enhanced Fe uptake. The enhancement of Fe uptake resulted from the uptake of FeFOB and FePSB by microorganisms adhering to the rhizoplane or living in the free space of cortical cells. The microbial apoplastic Fe pool was not available for root to shoot transport or, thus, for utilization by the plants. These results, in addition to the low uptake rate under axenic conditions, are in contrast to earlier hypotheses suggesting the existence of a specific uptake system for Fe siderophores in higher plants. The bacterial siderophores PSB and FOB were inefficient as Fe sources for plants even when supplied by stem injection. It was concluded that microorganisms are involved in degradation processes of microbial siderophores, as well as in competition for Fe with higher plants.

Magnesium deficiency and high light intensity enhance activities of superoxide dismutase, ascorbate peroxidase, and glutathione reductase in bean leaves.

The influence of varied Mg supply (10-1000 micromolar) and light intensity (100-580 microeinsteins per square meter per second) on the concentrations of ascorbate (AsA) and nonprotein SH-compounds and the activities of superoxide dismutase (SOD; EC 1.15.11) and the H(2)O(2) scavenging enzymes, AsA peroxidase (EC 1.11.1.7), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2) were studied in bean (Phaseolus vulgaris L.) leaves over a 13-day period. The concentrations of AsA and SH-compounds and the activities of SOD and H(2)O(2) scavenging enzymes increased with light intensity, in particular in Mg-deficient leaves. Over the 12-day period of growth for a given light intensity, the concentrations of AsA and SH-compounds and the activities of these enzymes remained more or less constant in Mg-sufficient leaves. In contrast, in Mg-deficient leaves, a progressive increase was recorded, particularly in concentrations of AsA and activities of AsA peroxidase and glutathione reductase, whereas the activities of guaiacol peroxidase and catalase were only slightly enhanced. Partial shading of Mg-deficient leaf blades for 4 days prevented chlorosis, and the activities of the O(2) (.-) and H(2)O(2) scavenging enzymes remained at a low level. The results demonstrate the role of both light intensity and Mg nutritional status on the regulation of O(2) (.-) and H(2)O(2) scavenging enzymes in chloroplasts.

Role of the root apoplasm for iron acquisition by wheat plants.

The role of the root apoplasm for iron acquisition was studied in wheat (Triticum aestivum L. cv Ares) grown in nutrient solution under controlled environmental conditions. To obtain different levels of Fe in the root apoplasm, plants were supplied in the dark for 5 hours (preloading period) with various (59)Fe-labeled Fe compounds [Fe(III) hydroxide; microbial siderophores: Fe rhodotorulic acid (FeRDA) and ferrioxamin (FeDesferal(3)), and synthetic Fe chelate (FeEDDHA)], each at a concentration of 5 micromolar. Large pools of apoplasmic Fe were formed after supplying Fe(III) hydroxide or FeRDA, but no such pools were observed after supplying FeDesferal or FeEDDHA. Depending on plant Fe nutritional status (preculture +/- 0.1 millimolar FeEDTA), apoplasmic Fe was used to different extent for translocation to the shoot. Under Fe deficiency, a much greater fraction of the apoplasmic Fe was utilized than in Fe-sufficient plants, as a result of the different rates of phytosiderophore release. Because of the diurnal rhythm in release of phytosiderophores in Fe-deficient plants, the utilization of the apoplasmic Fe for translocation into the shoot started 2 hours after onset of the light period and was dependent on the concentration of Fe in the apoplasm, which followed the order: Fe(III) hydroxide >> FeRDA >> FeDesferal = FeEDDHA. From these results, it can be concluded that in soil-grown plants the apoplasmic Fe pool loaded by various indigenous Fe compounds such as siderophores in the soil solution can be an important Fe source in graminaceous species, particularly during periods of limited Fe supply from the soil.

Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots.

The recent proposal of Tipton and Thowsen (Plant Physiol 79: 432-435) that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prélude) plants. The role of O(2) in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O(2). However, in the presence of O(2) the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O(2) ([unk]), as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron transport in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O(2) ([unk]) may have in the acquisition of ferric iron by dicotyledonous plants.

Evidence for a specific uptake system for iron phytosiderophores in roots of grasses.

Roots of grasses in response to iron deficiency markedly increase the release of chelating substances (;phytosiderophores') which are highly effective in solubilization of sparingly soluble inorganic Fe(III) compounds by formation of Fe(III)phytosiderophores. In barley (Hordeum vulgare L.), the rate of iron uptake from Fe(III)phytosiderophores is 100 to 1000 times faster than the rate from synthetic Fe chelates (e.g. Fe ethylenediaminetetraacetate) or microbial Fe siderophores (e.g. ferrichrome). Reduction of Fe(III) is not involved in the preferential iron uptake from Fe(III)phytosiderophores by barley. This is indicated by experiments with varied pH, addition of bicarbonate or of a strong chelator for Fe(II) (e.g. batho-phenanthrolinedisulfonate). The results indicate the existence of a specific uptake system for Fe(III)phytosiderophores in roots of barley and all other graminaceous species. In contrast to grasses, cucumber plants (Cucumis sativus L.) take up iron from Fe(III)phytosiderophores at rates similar to those from synthetic Fe chelates. Furthermore, under Fe deficiency in cucumber, increased rates of uptake of Fe(III)phytosiderophores are based on the same mechanism as for synthetic Fe chelates, namely enhanced Fe(III) reduction and chelate splitting. Two strategies are evident from the experiments for the acquisition of iron by plants under iron deficiency. Strategy I (in most nongraminaceous species) is characterized by an inducible plasma membrane-bound reductase and enhancement of H(+) release. Strategy II (in grasses) is characterized by enhanced release of phytosiderophores and by a highly specific uptake system for Fe(III)phytosiderophores. Strategy II seems to have several ecological advantages over Strategy I such as solubilization of sparingly soluble inorganic Fe(III) compounds in the rhizosphere, and less inhibition by high pH. The principal differences in the two strategies have to be taken into account in screening methods for resistance to ;lime chlorosis'.

An Improved Method for Non-destructive Measurements of the pH at the Root-Soil Interface (Rhizosphere).

A simple and non-destructive method is described which allows the measurement of the rhizosphere pH of soil-grown plants simultaneously, by optical methods (pH indicator) and by microelectrodes. The surface of the root-soil interface is covered by a prefixed thin sheet ( ~3 mm) of agar mixed with a pH indicator (e.g. bromocresol green). Following observations of the pH changes in the agar, detailed measurements of the pH can be made by pushing antimony microelectrodes through the agar into the rhizosphere. Examples are presented of the pH gradients along the roots of both, 4 year old Norway Spruce trees supplied with NH(4)-N or NO(3)-N (pot experiment) and 60 year old Norway Spruce trees grown on acid mineral soil. In long unbranched roots a distinct pH gradient occurs in the rhizosphere with high values in basal and apical zones and low values in the zone 2 - 5 em behind the root apex. The rhizosphere pH can therefore be considerably higher or lower compared to the bulk soil. This method can be used to accurately measure the pH gradient across the rhizosphere, even by distances less than 1 mm from the root surface. These root-induced pH changes could considerably affect microbial activity and solubility of mineral elements in the rhizosphere and thus also mineral element uptake particularly on acid soils.

Localization and capacity of proton pumps in roots of intact sunflower plants.

Proton extrusion by roots of intact sunflower plants (Helianthus annuus L.) was studied in nutrient solutions or in agar media with a pH indicator. Proton extrusion was enhanced by either iron deficiency, addition of fusicoccin, or single salt solutions of ammonium or potassium salts. The three types of proton extrusion differ in both localization along the roots and capacity. From their sensitivity to ATPase inhibitors it seems justified to characterize them as proton pumps driven by plasma membrane APTases.Enhanced proton extrusion induced by preferential cation uptake from (NH(4))(2)SO(4) or K(2)SO(4) was uniformly distributed over the whole root system. In contrast, the enhancement effect of fusicoccin was confined to the basal root zones and that of iron deficiency to the apical root zones. Also the rates of proton extrusion per unit of root fresh weight differed remarkably and increased in the order: Fusicoccin << K(2)SO(4) < (NH(4))(2)SO(4) < iron deficiency.Under iron deficiency the average values of proton extrusion for the whole root system are 5.6 micromoles H(+) per gram fresh weight per hour; however, for the apical root zones values of about 28 micromoles H(+) can be calculated. This high capacity is most probably related to the iron deficiency-induced formation of rhizodermal transfer cells in the apical root zones. It can be assumed that the various types of root-induced acidification of the rhizosphere are of considerable ecological importance for the plant-soil relationships in general and for mobilization of mineral nutrients from sparingly soluble sources in particular.

Accumulation of zinc and Organic Acids in Roots of Zinc Tolerant and Non-tolerant Ecotypes of Deschampsia caespitosa.

A much higher zinc level was necessary to inhibit root elongation in the zinc tolerant ecotype as compared to the non-tolerant ecotype of Deschampsia caespitosa. In the presence of a range of high levels of zinc, zinc accumulated to a much higher concentration in the roots of the tolerant ecotype, especially in the root sap. Accumulation of citrate in the root sap was highly correlated to the accumulation of zinc. Gel filtration chromatography of the root sap showed zinc to be mainly present as zinc-citrate. This was the only zinc complex found. The malate concentration of the root sap was much lower than the concentration of citrate. However the malate content of aqueous root homogenates was comparable or even greater than the content of citrate, suggesting that malate and citrate are located in different compartments within the cell. The results are consistent with a model of zinc tolerance in which zinc is complexed with citrate in the vacuole.

Mechanism of Short Term Fe Reduction by Roots : Evidence against the Role of Secreted Reductants.

The hypothesized role of secreted reducing compounds in Fe(III) reduction has been examined with Fe-deficient peanuts (Arachis hypogaea L. cv A124B). Experiments involved the exposure of roots to (a) different gas mixtures, (b) carbonyl cyanide m-chlorophenylhydrazone (CCCP), and (c) agents which impair membrane integrity.Removing roots from solution and exposing them to air or N(2) for 10 minutes did not result in any accumulation in the free space of compounds capable of increasing rates of Fe(III) reduction when roots were returned to solutions. On the contrary, exposing roots to N(2) decreased rates of Fe(III) reduction. CCCP also decreased rates of Fe(III) reduction.Acetic acid and ethylenediaminetetraacetic acid (disodium salt) (EDTA) impaired the integrity and function of the plasma membranes of roots of Fe-deficient peanuts. That is, in the presence of acetic acid or EDTA, there was an efflux of K(+) from the roots; K(+) ((86)Rb) uptake was also impaired. Acetic acid increased the efflux from the roots of compounds capable of reducing Fe(III). However, both acetic acid and EDTA caused rapid decreases in rates of Fe(III) reduction by the roots. In addition to peanuts, acetic acid also decreased rates of Fe(III) reduction by roots of Fe-deficient sunflowers (Helianthus annuus L. cv Sobrid) but not maize (Zea mays L. cv Garbo).These results suggest that, at least in the short term, the enhanced Fe(III) reduction by roots of Fe-deficient plants is not due to the secretion of reducing compounds.

Mechanism of iron uptake by peanut plants : I. Fe reduction, chelate splitting, and release of phenolics.

Iron deficiency in peanuts (Arachis hypogeae L.) caused an increase in release of caffeic acid, a higher rate of Fe(III) reduction, and increased rates of both Fe(III) chelate splitting and iron uptake.Experiments on Fe(III) reduction by phenolics (in vitro experiments) and by roots of Fe-deficient peanuts exclude the direct involvement of released phenolics in Fe(III) reduction by roots: Fe(III) reduction by phenolics had a pH optimum higher than 8.0 and was strongly dependent on the concentration and the stability of the supplied Fe(III) chelates. In contrast, Fe(III) reduction by roots of Fe-deficient peanuts had a pH optimum of about 5.0 and was less dependent on the stability of the supplied Fe(III) chelates. Furthermore, the observed release of phenolics into nutrient solution would have to be at least 200 times higher to attain the reduction rates of roots of Fe-deficient peanuts. The results of these experiments support the idea of an enzymic reduction of Fe(III) on the plasmalemma of cortical cells of roots.

Induction of transfer-cell formation by iron deficiency in the root epidermis of Helianthus annuus L.

Helianthus annuus L. responds to iron deficiency by forming a thickened cortex and abundant root hairs in a zone near the root apex that corresponds to the primary developmental stage. Cytological investigations revealed that within 24 to 48 h of iron deficiency most of the peripheral cells differentiate into transfer cells. The wall labyrinth is always situated on the peripheral walls that face the external medium. The cytoplasm of these cells is characterized by numerous mitochondria, extensive rough endoplasmic reticulum, and large leucoplasts containing protein bodies. These observations are discussed in relation to the fact that Helianthus, as an "iron efficient" plant, responds physiologically to iron deficiency by extrusion of H(+), production of reducing substances, and a steep increase in the uptake efficiency of Fe.