Die Ölblumensymbiosen – Parallelismus and andere Aspekte ihrer Entwicklung in Raum and Zeit1, 2

The oil-bee/oil-flower relationships: parallelism and other aspects of their evolution in space and time A survey is given of our present knowledge and existing hypotheses concerning the biogeography, history, and phylogeny of plant taxa yielding fatty oil as a floral reward, and of the bee genera involved in their pollination. Four syngenetic complexes of the symbiosis arose convergently: The neotropical, the paleotropical, the holarctic, and the capensic complex. On the basis of the mutual structural adaptations of bees and flowers it is concluded that, in addition, parallelism within related groups as a result of a common tendency to develop the respective organs, has played an important role in the evolution of the oil-based floral interrelationships.     

Festkolloquium and Symposium "Präadaptation in der Evolution von Pflanze and Tier"

Zum Gelingen dieses Symposiums haben viele entscheidend beigetragen. Tatkräftige Hilfe bei der Organisation habe ich vielen Mitgliedern des Institutes zu verdanken. Stellvertretend für alle sollen nur Frau Dr. C. Gack and meine technische Assistentin, Frau Christine Gutmann , besonders crwähnt werden. Großzügige finanzielle Unterstützung erhielten wir von der Fa. Goedecke (Freiburg) und dem Herder-Verlag (Freiburg).     

Binding of Cd2+, Ni2+, Cu2+ and Zn2+ by isolated envelopes of Pseudomonas fluorescens

Abstract Cell envelopes of Pseudomonas fluorescens , cytoplasmic membrane, peptidoglycan and outer membrane were obtained from a fractionation procedure and tested for their metal binding capacity. Isolated envelopes (cytoplasmic membrane, peptidoglycan and outer membrane) were chemically modified and functional carboxyl groups transformed to electropositive amine groups, using carbodiimide ethylenediamine. Transformation of carboxyl groups was evaluated by measuring total amine groups in all fractions (modified or not). Using equilibrium dialysis and Scatchard plots for the data, we have established that isolated unmodified cell envelopes (cytoplasmic membrane, peptidoglycan and outer membrane) possess at least two types of metal binding sites with different association constants ( K _a and K '_a). Introduction of positive charges into the bacterial envelopes resulted in the disappearance of one type of metal binding site which had the highest association constant value for Ni²⁺, Cu²⁺ and Zn²⁺. All fractions, modified or not, always presented at least two types of binding sites with different association constants for Cd²⁺.     

Excretion of ions (Cd2+, Li+, Na+ and Cl−) by Tamarix aphylla

Excretion of minerals by the NaCl-resistant and comparatively cadmium-resistant tree Tamarix aphylla (L.) Karst, was investigated. Cd²⁺ was excreted by plants exposed for 1–10 days to 9 or 45 μ M Cd²⁺ solutions. Excretion of this toxic ion increased considerably with time but was less than 5% of the quantities that had been accumulated in the shoots. Excretion of Na⁺ and Cl⁻ was positively correlated with NaCl concentration (1.5, 10, 50 m M ) of the medium. The Na⁺/Cl⁻ ratios of the excrete were positively correlated with the concentration of the treatment solution. Ca²⁺ excretion decreased with increasing NaCl concentrations of the solution. Excretion of K⁺ and Mg²⁺ was only little affected by NaCl. Excretion of Li⁺ occurred whenever this element was supplied in the uptake solution; daily excretion rates of Li⁺ increased with time. The ecological significance of excretion is discussed in relation to the low selectivity of the mechanism in T. aphylla .     

Blue-light-induced pH changes associated with NO3−, NO2− and Cl− uptake by the green alga Monoraphidium braunii

In M. braunii, the uptake of NO₃⁻ and NO₂⁻ is blue-light-dependent and is associated with alkalinization of the medium. In unbuffered cell suspensions irradiated with red light under a CO₂-free atmosphere, the pH started to rise 10s after the exposure to blue light. When the cellular NO₃⁻ and NO₂⁻ reductases were active, the pH increased to values of around 10, since the NH₄⁺ generated was released to the medium. When the blue light was switched off, the pH stopped increasing within 60 to 90s and remained unchanged under background red illumination. Titration with H₂SO₄ of NO₃⁻ or NO₂⁻ uptake and reduction showed that two protons were consumed for every one NH₄⁺ released. The uptake of Cl⁻ was also triggered by blue light with a similar 10 s time response. However, the Cl⁻ -dependent alkalinization ceased after about 3 min of blue light irradiation. When the blue light was turned off, the pH immediately (15 to 30 s) started to decline to the pre-adjusted value, indicating that the protons (and presumably the Cl⁻) taken up by the cells were released to the medium. When the cells lacked NO₃⁻ and NO₂⁻ reductases, the shape of the alkalinization traces in the presence of NO₃⁻ and NO₂⁻ was similar to that in the presence of Cl⁻, suggesting that NO₃⁻ or NO₂⁻ was also released to the medium. Both the NO₃⁻ and Cl⁻-dependent rates of alkalinization were independent of mono- and divalent cations.     

Effects of interrupted K+ supply on growth and uptake of K+, Ca2+, Mg2+ and Na+ in spring wheat

Effects of interrupted K⁺ supply on different parameters of growth and mineral cation nutrition were evaluated for spring wheat (Triticum aestivum L. cv. Svenno). K⁺ (2.0 mM) was supplied to the plants during different periods in an otherwise complete nutrient solution. Shoot growth was reduced before root growth after interruption in K⁺ supply. Root structure was greatly affected by the length of the period in K⁺ -free nutrient solution. Root length was minimal, and root branching was maximal within a narrow range of K⁺ status of the roots. This range corresponded to cultivation for the last 1 to 3 days, of 11 in total, in K⁺ -free nutrient solution, or to continuous cultivation in solution containing 0.5 to 2 mM K⁺. In comparison, both higher and lower internal/external K⁺ concentrations had inhibitory effects on root branching. However, the differing root morphology probably had no significant influence on the magnitude of Ca²⁺, Mg²⁺ and Na⁺ uptake. Uptake of Ca²⁺ and especially Mg²⁺ significantly increased after K⁺ interruption, while Na⁺ uptake was constant in the roots and slowly increased in the shoots. The two divalent cations could replace K⁺ in the cells and maintain electroneutrality down to a certain minimal range of K⁺ concentrations. This range was significantly higher in the shoot [110 to 140 μmol (g fresh weight)^?1] than in the root [20 to 30 μmol (g fresh weight)^?1]. It is suggested that the critical K⁺ values are a measure of the minimal amount of K⁺ that must be present for physiological activity in the cells. At the critical levels, K⁺ (⁸⁶Rb) influx and Ca²⁺ and Mg²⁺ concentrations were maximal. Below the critical K⁺ values, growth was reduced, and Ca²⁺ and Mg²⁺ could no longer substitute for K⁺ for electrostatic balance. In a short-term experiment, the ability of Ca²⁺ to compete with K⁺ in maintaining electroneutrality in the cells was studied in wheat seedlings with different K⁺ status. The results indicate that K⁺, which was taken up actively and fastest at the external K⁺ concentration used (2.0 mM), partly determines the size of Ca²⁺ influx.     

Hydrolysis of glucuronide-based substrates mediated by tungsten, Cu2+, Fe2+, and Zn2+

A variety of metal microprojectiles are currently used for carrying foreign DNA into living cells via particle-acceleration techniques. While developing a microprojectile-mediated protocol for transforming cells of sugarbeet ( Beta vulgaris L.), formation of a blue precipitate was observed with the indigoqenic substrate 5-bromo-4-chloro-3-indolyl-β-D-glucuronic acid (X-gluc) in the absence of gusA DNA encoding β-D-glucuronidase (GUS). Tungsten microcarriers, but not gold or silicon carbide, proved capable of catalyzing the cleavage of the glucuronide residue from three histochemical substrates evaluated: X-gluc, salmon X-gluc and magenta X-gluc. Indigo-stained sugarbeet cells were observed following bombardment with tungsten in the absence of DNA. Addition of oxidative catalysts to tungsten microcarriers during substrate incubation had no apparent effect on the metal-mediated catalysis. Treatment of microcarriers with Proteinase K and heat ruled out the presence of enzymes. Microbiological evaluation indicated the absence of contaminating microbes. Similarly, metal-catalyzed hydrolysis of the fluorogenic substrate 4-methylumbelliferyl-β-D-glucuronic acid (4-MUG) was observed in the presence of tungsten spheres but not with gold or silicon carbide particles. With this substrate, hydrolysis also occurred with millimolar concentrations of Cu²⁺, Fe²⁺ and Zn²⁺ ions. Consequently, careful monitoring of DNA-minus controls and avoidance of millimolar concentrations of Cu²⁺, Fe²⁺ and Zn²⁺ ions are recommended in microprojectile bombardment experiments where transient assays for gusA expression are performed.     

Photophosphorylation in Scenedesmus in vivo: O2 evolution, ATP pools and transients, and phosphate binding during photoreduction of NO3−, NO2− and CO2

The relation between light-induced electron transport with NO₃^?, NO₂^? or CO₂ as acceptors, ATP pools and transients in dark-light-dark transitions, and phosphate uptake was examined in phosphorus-starved cells of Scenedesmus obtusiusculus Chod. Net O₂ evolution at saturating light was around 6 μmol × (mg chlorophyll × h)^?1 in the absence of any acceptor, but reached average rates of 21, 65 and 145 μmol × (mg chlorophyll × h)^?1 upon additions of 5 mM KNO₃, KNO₂ and KHCO₃, respectively. The apparent rate of photophosphorylation in transition experiments was only a few percent of the rate calculated from CO₂-dependent O₂ evolution. Blocking non-cyclic electron transport with DCMU inhibited phosphate assimilation, but acceleration of non-cyclic electron flow by addition of NO₃^? or NO₂^? did not stimulate phosphate assimilation as compared to the situation without an acceptor. A functional non-cyclic system might primarily be needed for an efficient shuttle transfer of ATP from the chloroplast to the cytoplasm. An inhibition of the non-cyclic system due to lack of reducible substrates accelerates the cyclic system and thus indicates a regulation mechanism between the two systems.     

Tyrosine Hydroxylase Phosphorylation in Bovine Adrenal Chromaffin Cells: The Role of Intracellular Ca2+ in the Histamine H1 Receptor-Stimulated Phosphorylation of Ser8, Ser19, Ser31, and Ser40

Abstract: Tyrosine hydroxylase (TOH), the rate-limiting enzyme in catecholamine biosynthesis, is regulated by phosphorylation. Activation of histaminergic H₁ receptors on cultured bovine adrenal chromaffin cells stimulated a rapid increase in TOH phosphorylation (within 5 s) that was sustained for at least 5 min. The initial increase in TOH phosphorylation (up to 1 min) was essentially unchanged by the removal of extracellular Ca²⁺. In contrast, the H₁-mediated response was abolished by preloading the cells with BAPTA acetoxymethyl ester (50 µ M ) and significantly reduced by prior exposure to caffeine (10 m M for 10 min) to deplete intracellular Ca²⁺. Trypticphosphopeptide analysis by HPLC revealed that the H₁ response in the presence or absence of extracellular Ca²⁺ resulted in a major increase in the phosphorylation of Ser¹⁹ with smaller increases in that of Ser⁴⁰ and Ser³¹. In contrast, although a brief stimulation with nicotine (30 µ M for 60 s) also resulted in a major increase in Ser¹⁹ phosphorylation, this response was abolished in the absence of extracellular Ca²⁺. These data indicate that the mobilization of intracellular Ca²⁺ plays a crucial role in supporting H₁-mediated TOH phosphorylation and may thus have a potentially important role in regulating catecholamine synthesis.     

Differential effects of Na+, Mg2+, K+, Ca2+ and osmotic stress on the wild type and the NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii

In order to identify physiological components that contribute to salinity tolerance, we compared the effects of Na⁺, Mg²⁺ and K⁺ salts (NaCl, Na₂SO₄, MgCl₂, MgSO₄, KCl and K₂SO₄), Ca₂₊ (CaSO₄), mannitol and melibiose on the wild type and the single-gene NaCl-tolerant mutants stl1 and stl2 of Ceratopteris richardii. Compared with gametophytic growth of the wild type, stl2 showed a low level of tolerance that was restricted to Na⁺ salts and osmotic stress. stl2 exhibited high tolerance to both Na⁺ and Mg²⁺ salts, as well as to osmotic stress. In response to short-term exposure (3 d) to NaCl, accumulation of K⁺ and Na⁺ was similar in the wild type and stl1. In contrast, stl2 accumulated higher levels of K⁺ and lower levels of Na⁺. Ca²⁺ supplementation (1.0 mol m^?3) ameliorated growth inhibition by Na⁺ and Mg²⁺ stress in wild type and stll, but not in stl2. In addition, under Na⁺ stress (175 mol m^?3) wild-type, stll and stl2 gametopbytes maintained higher tissue levels of K⁺ and lower levels of Na⁺ when supplemented with Ca²⁺ (1.0 mol m^?3). stl2 gametophytes were extremely sensitive to K⁺ supplementation. Growth of stl2 was greater than or equal to that of the wild type at trace concentrations of K⁺ but decreased substantially with increasing K⁺ concentration. Supplementation with K⁺ from 0 to 1.85 mol m^?3 alleviated some of the inhibition by 75 mol m^?3 NaCl in the wild type and in stl1. In stl2, growth at 75 mol m^?3 NaCl was similar at 0 and 1.85 mol m^?3 K⁺ supplementation. Although K⁺ supplementation above 1.85 mol m^?3 did not alleviate inhibition of growth by Na⁺ in any genotype, stl2 maintained greater relative tolerance to NaCl at all K⁺ concentrations tested.     

Equine marker genes. Polymorphism for transferrin alleles, TfF1 and TfF2, in Thoroughbreds

The equine transferrin F variant is distinguishable into two types, F1 and F2, on alkaline polyacrylamide gel electrophoresis. Gene frequencies in 63 related Thoroughbreds are 0.39 and 0.19 for TfF¹TfF², respectively. In contrast the frequencies for these two alleles in 375 related Standardbreds is 0.00 and 0.59.     

Stimulation of proton extrusion by K+ and divalent cations (Ni2+, Co2+ Zn2+) in maize root segments

Entry of the divalent cations Ni²⁺, Co²⁺ and Zn²⁺ into cells of maize ( Zea mays L. cv. Dekalb XL 85) root tissue is accompanied by an acidification of the incubation medium, a decrease in both the pH of the cell sap and the level of malate in the cells, and by an inhibition of dark fixation of CO₂. K⁺, on the contrary, induces only a very low acidification of the incubation medium, does not change either the pH of the cell sap or the malate level in the cells, and induces an increase in CO₂ dark fixation. Different mechanisms are postulated for the stimulation of proton extrusion by divalent cations and K⁺.     

Cadmium-induced subcellular accumulation of O2·− and H2O2 in pea leaves

Cadmium is a toxic metal that produces disturbances in plant antioxidant defences giving rise to oxidative stress. The effect of this metal on H₂O₂ and O₂^·? production was studied in leaves from pea plants growth for 2 weeks with 50 µm Cd, by histochemistry with diaminobenzidine (DAB) and nitroblue tetrazolium (NBT), respectively. The subcellular localization of these reactive oxygen species (ROS) was studied by cytochemistry with CeCl₃ and Mn/DAB staining for H₂O₂ and O₂^·?, respectively, followed by electron microscopy observation. In leaves from pea plants grown with 50 µm CdCl₂ a rise of six times in the H₂O₂ content took place in comparison with control plants, and the accumulation of H₂O₂ was observed mainly in the plasma membrane of transfer, mesophyll and epidermal cells, as well as in the tonoplast of bundle sheath cells. In mesophyll cells a small accumulation of H₂O₂ was observed in mitochondria and peroxisomes. Experiments with inhibitors suggested that the main source of H₂O₂ could be a NADPH oxidase. The subcellular localization of O₂^·? production was demonstrated in the tonoplast of bundle sheath cells, and plasma membrane from mesophyll cells. The Cd‐induced production of the ROS, H₂O₂ and O₂^·?, could be attributed to the phytotoxic effect of Cd, but lower levels of ROS could function as signal molecules in the induction of defence genes against Cd toxicity. Treatment of leaves from Cd‐grown plants with different effectors and inhibitors showed that ROS production was regulated by different processes involving protein phosphatases, Ca²⁺ channels, and cGMP.     

Effects of Cd2+ and EDTA on young sugar beets (Beta vulgaris). II. Net uptake and distribution of Mg2+, Ca2+ and Fe2+/Fe3+

Levels of Mg²⁺, Ca²⁺ and Fe²⁺/Fe³⁺ were determined in roots and shoots of sugar beet seedlings (Beta vulgaris L. cv. Monohill) cultured for 5 weeks in a complete nutrient solution to which either Cd²⁺ (0, 5 or 50 μM), EDTA (0, 10 or 100 μM) or a combination of both was added. The plants subjected to the various treatments showed a variety of deficiency symptoms. Leaves of the Cd²⁺-treated plants became thin and chlorotic (Mg- and Fe-deficiency symptoms). The plants showed reduced growth and developed only a few brownish roots with short laterals (Ca-deficiency symptoms). EDTA treatment resulted in green, stunted, hard leaves and reduced growth (Ca-deficiency symptoms). The deficiency symptoms observed correspond well with the observed uptake rates and distributions of Mg²⁺, Ca²⁺ and Fe²⁺/Fe³⁺. Increases in either Cd²⁺, EDTA or a combination of both in the growth medium, were correlated with increasing Mg²⁺ levels in the roots and with decreasing Mg²⁺ levels in the shoots. Cd²⁺ alone or in combination with EDTA had little influence on Ca²⁺ levels in the shoots but decreased Ca²⁺ levels in the roots. Thus, Cd²⁺ affects Mg²⁺ and Ca²⁺ transport in opposite ways: Mg²⁺ transport to the shoots is inhibited while that of Ca²⁺ is facilitated. Treatment with EDTA alone did not affect Ca²⁺ concentrations in either the shoots or the roots. Treatment with Cd²⁺ lowered Fe²⁺ concentrations in both roots and shoots.     

l-Methionine-dl-sulfoximine resistant Het+ Nif+ and Het− Nif− strains of Nostoc muscorum assimilating methylamine as ammonium nitrogen source

Abstract The Het⁺ Nif⁺ and Het⁻ Nif⁻ strains of Nostoc muscorum sensitive to growth inhibition by methylamine (MA), overcame the MA inhibition as a result of their mutation to l -methionine- dl -sulfoximide (MSX)-resistant phenotype, which enabled them to assimilate MA like an ammonium nitrogen source. The MSX-resistant Het⁺ Nif⁺ strain synthesized the inhibitor-resistant transferase-defective glutamine synthetase (GS), which unlike parental GS underwent MA-dependent in vivo activation. These results suggest the involvement of GS enzyme in control of MA assimilation in cyanobacteria.