Transient state characteristics of adaptation to changes in light conditions for the cyanobacterium Oscillatoria agardhii

Transitions in growth irradiance level from 92 to 7 Em^-2 s^-1 and vice versa caused changes in the pigment contents and photosynthesis of Oscillatoria agardhii. The changes in chlorophyll a and C-phycocyanin contents during the transition from high to low irradiance (HL) were reflected in photosynthetic parameters. In the LH transition light utilization efficiencies of the cells changed faster than pigment contents. This appeared to be related to the lowering of light utilization efficiencies of photosynthesis. As a possible explanation it was hypothesized that excess photosynthate production led to feed back inhibition of photosynthesis. Time-scales of changes in the maximal rate of O₂ evolution were discussed as changes in the number of reaction centers of photosystem II in relation to photosynthetic electron transport. Parameters that were subject to change during irradiance transitions obeyed first order kinetics, but hysteresis occurred when comparing HL with LH transients. Interpretation of first order kinetic analysis was discussed in terms of adaptive response vs changes in growth rate.Non-standard abbreviations Chla chlorophyll a - CPC C-phycocyanin - PS II photosystem II - PS I photosystem I - RC II reaction center of photosystem II - P photosynthetic O₂-evolution - I irradiance, Em^-2 s^-1 - light utilization efficiency of cells, mmol O₂·mg dry wt^-1·h^-1/Em^-2 s^-1 - light utilization efficiency of photosynthetic apparatus, mol O₂·mol Chla ^-1·h^-1/Em^-2 s^-1 - P_max maximal rate of O₂ evolution by cells, mol O₂·mg dry wt^-1·h^-1 - P_max maximal rate of O₂ evolution by photosynthetic apparatus, mol O₂·mol·Chla ^-1·h^-1 - LL low light, E m^-2 s^-1 - HL high light, E m^-2 s^-1 - LH low to high light transition - HL high to low light transition - k specific rate of adaptation, h^-1 - specific growth rate, h^-1 - Q pool size of cell constituent, mol·mg dry wt^-1 - q net synthesis rate of cell constituent, mol·mg dry wt^-1·h^-1     

Na/H exchange in cultured epithelial cells from fish gills

Using primary cultures of gill pavement cells from freshwater rainbow trout, a method is described for achieving confluent monolayers of the cells on glass coverslips. A continuous record of intracellular pH was obtained by loading the cells with the pH-sensitive flourescent dye 2,7-bis(2-carboxyethyl)-5(6)-carboxyfluorescein and mounting the coverslips in the flowthrough cuvette of a spectrofluorimeter. Experiments were performed in HEPES-buffered media nominally free of HCO₃. Resting intracellular pH (7.43 at extracellular pH=7.70) was insensitive to the removal of Cl^– or the application of 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid (0.1 mmol·l^–1), but fell by about 0.3 units when Na⁺ was removed or in the presence of amiloride (0.2 mmol·l^–1). Exposure to elevated ammonia (ammonia prepulse; 30 mmol·l^–1 as NH₄Cl for 6–9 min) produced an increase in intracellular pH (to about 8.1) followed by a slow decay, and washout of the pulse caused intracellular pH to fall to about 6.5. Intracellular non-HCO ₃ ^– buffer capacity was about 13.4 slykes. Rapid recovery of intracellular pH from intracellular acidosis induced by ammonia prepulse was inhibited more than 80% in Na⁺-free conditions or in the presence of amiloride (0.2 mmol·l^–1). Neither bafilomycin A₁ (3 mol·l^–1) nor Cl removal altered the intracellular pH recovery rate. The K _m for Na⁺ of the intracellular pH recovery mechanism was 8.3 mmol·l^–1, and the rate constant at V _max was 0.008·s^–1 (equivalent to 5.60 mmol H⁺·l^–1 cell water·min^–1), which was achieved at external Na⁺ levels from 25 to 140 mmol·l^–1. We conclude that intracellular pH in cultured gill pavement cells in HEPES-buffered, HCO ₃ ^– -free media, both at rest and during acidosis, is regulated by a Na⁺/H⁺ antiport and not by anion-dependent mechanisms or a vacuolar H⁺-ATPase.Abbreviations BCECF 2,7-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein - BCECF/AM 2,7-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein, acetoxymethylester - Cholin-Cl choline chloride - DMSO dimethyl sulfoxide - EDTA ethylene diamine tetra-acetic acid - FBS foetal bovine serum - H ⁺ -ATPase Proton-dependent adenosine triphosphatase - HEPES N-[2-hydroxyethyl]piperazine-N[2-ethanesulfonic acid] - pH _i intracellular pH - pH _e extracellular pH - PBS phosphate-buffered saline - SITS 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid     

Degradation of phenol by a coimmobilized entrapped mixed culture

Summary The degradation of phenol by a defined mixed culture, consisting of Pseudomonas putida P8 and Cryptococcus elinovii H1, was studied. The microorganisms were entrapped either in 30 g·l^-1 calcium-alginate or in chitosan-alginate. Chitosan-alginate entrapment was suitable for a continuous culture. The coimmobilized mixed culture of Cryptococcus elinovii H1 which degrades phenol via an ortho pathway and of Pseudomonas putida P8 which uses the meta cleavage pathway was able to degrade high phenol concentrations up to 3.2 g·l^-1 in semicontinuous cultures. The degradation performance in continuous cultures could reach a maximum of 0.41 g·l^-1·h^-1 phenol. The mixed culture could be stored for up to six months without loss of phenol degradation capacity.Dedicated to Professor Dr. Dr. h. c. K. Esser on the occasion of his 65th birthday     

Development of aldosterone-stimulation of short-circuit current across larval frog skin

Summary The short-circuit current (SCC) across isolated skin from bullfrog larvae in developmental stage XXI was small and insensitive to amiloride. Overnight incubation of this tissue with 10^-6 M aldosterone stimulated the SCC from 1.35±0.55 to 14.55±4.12 A·cm^-2 with 11.18±4.46 A·cm^-2 being blocked by 100 M amiloride. Histologic examination of aldosterone-treated skins revealed a separation of the apical cell layer from the underlying epidermis that was not seen in untreated preparations. The onset of amiloride-sensitive Na⁺ transport thus coincided with the exposure of the apical surface of newly differentiated epithelial cells. Similar results were obtained with skin from stage XXI larvae whose rate of metamorphosis had been stimulated by 10 g·l^-1 thyroxine (T₄) but not with skin from T₄-treated larvae in stages XIX and XX. Fluctuation analysis of the amiloride-sensitive SCC of the above preparations failed to show a consistent Lorentzian component in the power-density spectrum. Fluctuation analysis was possible on skins from larvae whose development had been accelerated by 7–9 days treatment with 10 g·l^-1 triiodothyronine (T₃). Aldosterone treatment of these tissues resulted in a significant increase in Na⁺ channel density.Abbreviations ASCC component of the short-circuit current (A·cm^-2) that is blocked by amiloride - fc frequency (Hz) at which the magnitude of the Lorenzian component of the power spectra is reduced by half - i current (pA) through individual amiloride-sensitive Na⁺ channels - I _Na+ amiloride-sensitive short-circuit current (A·cm^-2) that remains after treatment with a given amiloride concentration - k ₀₁ the rate constant (s^-1·M^-1) for the association of amiloride with Na⁺ channels - k ₁₀ rate constant (s^-1) for the dissociation of amiloride from Na⁺ channels - K _b magnitude of the power spectrum (A²·s·cm^-2) at a frequency of 1 Hz - KSCC short-circuit (A·cm^-2) current with K⁺ as the primary mucosal cation - M density of amiloride-sensitive Na⁺ channels in the apical cell membrane - SCC short-circuit current (A·cm^-2) - S _(f) magnitude of the power spectra (A²·s·cm^-2) at a given frequency - S ₀ the magnitude of the plateau region of the Lorentzian component of the power spectra (A²·s·cm^-2) - T ₃ Triiodothyronine - T ₄ Thyroxine     

Production of alkaloids by in vitro culture of Erythrina americana Miller

The production of erythroidines and other alkaloids was studied in cotyledons, callus and cell suspension cultures of Erythrina americana Miller. The cell suspension cultures, grown in Murashige & Skoog medium with naphthaleneacetic acid (3 mg l^–1) and kinetin (2 mg l^–1), produced 89 and 17 g - and -erythroidines respectively per g dry wt.     

High-affinity amylolytic enzymes produced by the mould Trichoderma harzianum

Summary The apparent substrate constants of the amylolytic enzymes produced by the mould Trichoderma harzianum CBS 354.33 were measured. The value for -amylase was 64 mg starch·1^-1 which is very low as compared with those of other -amylases. The substrate constant for glucoamylase was 78 mg starch·l^-1. Both enzymes were sensitive to Acarbose; 50% inhibition was observed at 2.5 mg·l^-1 (-amylase) and 0.10 mg·l^-1 (glucoamylase).     

Photoautotrophic micropropagation of Russet Burbank Potato

The photoautotrophic micropropagation of potato cv. Russet Burbank was investigated. Single node microcuttings were grown for four weeks on Murashige and Skoog (MS) medium with or without sucrose (30 g l^–1) in the growth room at 21/19 °C day/night temperature, with 16-h photoperiod at 150 mol m^–2 s^–1, with or without supplemental CO₂ at 1500 l l^–1. A 20% increase in the number of nodes per stem (from 7.5 to 9.4) and a 50% increase in stem dry weight were observed in cultures grown on media with sucrose and in CO₂ enriched atmosphere comparing to the conventionally micropropagated cultures or the cultures grown photoautotrophically on media without sucrose but in air supplemented with 1500 l l^–1CO₂. Stems of these cultures (from media with sucrose in CO₂ enriched air) almost doubled in length the stems of cultures from the other two treatments. No significant differences were observed between Control (MS medium supplemented with sucrose, 30 g l^–1) and photoautotrophic cultures coming from MS medium with no sucrose grown under 1500 l l^–1 of CO₂. Photoautotrophic cultures produced stems averaging 43.3 mm, with 7 nodes and weighing 9.2 mg (dry weight), similar to conventionally grown in vitro cultures (47.9 mm with 7.5 nodes, 9.7 mg dry weight). Growers may consider photoautotrophic culturing of potato in areas where the high sterility levels are difficult to maintain. Supplementing air in the growth room with 1500 l l^–1 of CO₂ could be beneficial for potato plantlet production even on media containing sucrose since it significantly improved quality, size and biomass of produced plantlets, speeding up the multiplication.     

Regulation of pH in the isolated perfused gills of the shore crabCarcinus maenas

Isolated posterior gills (no. 7) of shore crabsCarcinus maenas acclimated to brackish water of a salinity of 10 S were bathed and perfused with 50% sea water (200 mmol·l^-1 Na⁺), and the internal perfusate collected during subsequent periods of 5 min. During a single passage through the gill the pH of the perfusion medium decreased from ca. 8.1 to ca. 7.7, a result implying that the gill possesses structures which recognize unphysiologically high pH values in the haemolymph and regulates them down to physiological values of ca. 7.7. The calculated apparent proton fluxes from the epithelial cells into the haemolymph space amounted to 17.9 mol·g fw^-1·h^-1, a value of only 3.8% of net Na⁺ fluxes observed under comparable conditions. When 0.1 mmol·l^-1 KCN, an inhibitor of mitochondrial cytochrome oxidase, or 5 mmol·l^-1 ouabain, a specific inhibitor of Na⁺/K⁺-ATPase were applied in the internal perfusate, down-regulation of pH was no longer observed and the gill was completely depolarized, i.e. transepithelial potential differences dropped from-7.8 to 0 mV (haemolymph space negative to bath). Regulation of pH was completely inhibited by antagonists of carbonic anhydrase (0.1 mmol·l^-1 acetazolamide or 0.01 mmol·l^-1 ethoxyzolamide) applied in the perfusate. Inhibitors of Na⁺/H⁺ exchange, 0.1 mmol·l^-1 amiloride applied in the external bathing medium or in the internal perfusate, and symmetrical 0.01 mmol·l^-1 5-(N-ethyl-N-isopropyl)amiloride, as well as inhibitors of Cl^-/HCO₃ ^- exchange and Na⁺/HCO₃ ^- cotransport, 0.5 mmol·l^-1 4,4-diisothiocyanatostilbene-2,2-disulphonate or 0.3 mmol·l^-1 4-acetamido-4-isothiocyanatostilbene 2,2-disulphonate applied on both sides of the gill, and inhibitors of H⁺-ATPase, 0.05 mmol·l^-1 N-ethylmaleimide and 0.1 mmol·l^-1 N,N-dicyclohexylcarbodiimide —applied on both sides of the gill — did not alter the acidification of the perfusate observed in controls. Using artificial salines buffered to pH 8.1 with 0.75 mmol·l^-1 tris (hydroxymethyl) aminomethane instead of 2 mmol·l^-1 HCO₃ ^-, apparent proton fluxes were reduced to 11% of controls, a result suggesting that pH regulation by crab gills needs the presence of HCO₃ ^-. The findings obtained suggest that pH regulation by crab gills depends on the oxidative metabolism of the intact branchial epithelium and that carbonic anhydrase plays a central role in this process. Na⁺/H⁺ exchange, anion exchange or cotransport and active proton secretion seem not to be involved. While unimpaired active ion uptake is a prerequisite for pH regulation, ion transport itself is independent of it.Abbreviations acetazolamide (N-[sulphamoyl-1, 3, 4-thiadiazol-2-yl]-acetamide) - amiloride 3,5-diamino-6-chloropyrazinoyl-guanidine - CA carbonic anhydrase - DBI dextrane-bound inhibitor thiadiazolesulphonamide - DCCD N N dicyclohexylcarbodiimide - DIDS 4,4-diisothiocyanato-stilbene-2,2-disulphonate - EIPA 5-(N-ethyl-N-isopropyl) amiloride - ethoxyzolamide 6-ethoxy-2-benzothiazole-sulphonamide - fw fresh weight - J _H ⁺ apparent proton flux - NEM N-ethylmaleimide - PD transepithelial potential difference - PEG-STZ polyethylene-glycol-thiadiazolesulphonamide - STTS 4-acetamido-4-isothiocyanatostibene 2,2-disulphonate - SW sea water - TRIS tris(hydroxymethyl)aminomethane     

Increased taxane accumulation in callus cultures of Taxus cuspidata and Taxus × media by some elicitors and precursors

In Taxus cuspidata callus, vanadyl sulfate (10 mg l^–1) induced a high (146 g g^–1 dry wt) production of 10-deacetylbaccatin III in comparison to 7 g g^–1 dry wt of the control. The content of paclitaxel in this species increased from 16 g g^–1 to 74 g g^–1 dry wt when 20 mg phenylalanine l^–1 was used. In T. media, p-aminobenzoic acid induced the highest content of 10-deacetylbaccatin III (481 g g^–1 dry wt) versus 181 g g^–1 in the control. Paclitaxel increased from 89 to 139 g g^–1 dry wt after adding chitosan (20 mg l^–1) to the cultures.     

Book reviews

Consider the perturbed harmonic oscillator Ty=-y+x²y+q(x)y in L²(), where the real potential q belongs to the Hilbert space H={q, xq L²()}. The spectrum of T is an increasing sequence of simple eigenvalues _n(q)=1+2n+_n, n 0, such that _n 0 as n. Let _n(x,q) be the corresponding eigenfunctions. Define the norming constants _n(q)=lim_xlog |_n (x,q)/_n (-x,q)|. We show that for some real Hilbert space and some subspace Furthermore, the mapping :q(q)=({_n(q)}₀, {_n(q)}₀) is a real analytic isomorphism between H and is the set of all strictly increasing sequences s={s_n}₀ such that The proof is based on nonlinear functional analysis combined with sharp asymptotics of spectral data in the high energy limit for complex potentials. We use ideas from the analysis of the inverse problem for the operator -ypy, p L²(0,1), with Dirichlet boundary conditions on the unit interval. There is no literature about the spaces We obtain their basic properties, using their representation as spaces of analytic functions in the disk.     

Living cell reaction process forl-isoleucine andl-valine production

Summary A new process (Living Cell Reaction Process) forl-isoleucine production using viable, non-growing cells ofBrevibacterium flavum AB-07 was optimised using ethanol as the energy source and -ketobutyric acid (-KB) as precursor.l-valine also could be produced from glucose at high yield by this process. This process differs from the usual fermentation method in that non-growing cells are used, and the production ofl-isoleucine andl-valine were carried out under conditions of repressed cell division and growth. Minimal medium missing the essential growth factor, biotin was employed as the reaction mixture for the production ofl-isoleucine andl-valine. The productivity ofl-isoleucine andl-valine were 200 mmol·l^–1 · day^–1 (molecular yield to -KB: 95%) and 300 mmol · l^–1 · day^–1 (molecular yield to glucose: 80%) respectively. The content ofl-isoleucine andl-valine in total amino acids produced in the each mixture were 97% and 96% respectively.     

1H and13C-NMR analysis of four pentasaccharides from urine of blood-group A and B,Leb adults. Confirmation of the structure of two new oligosaccharides: Fuc(α1–2)[GalNAc(α1–3)]Gal(β1–3)[Fuc(α1–4)]Glc and Fuc(α1–2)[Gal(α1–3)]Gal(β1–3)[Fuc(α1–4)]Glc

The major pentasaccharides Fuc(1-2)[GalNAc(1-3)]Gal(1-4)[Fuc(1-3)]Glc and Fuc(1-2) [Gal(1-3)]Gal(1-4)[Fuc(1-3)]Glc, which are normally present in the urine of bloodgroup A Le^b and B Le^b healthy subjects, were each found to be contaminated by a minor component when analysed by¹H-NMR. The determination of these structures, Fuc(1-2) [GalNAc(1-3)]Gal(1-3)[Fuc(1-4)]Glc and Fuc(1-2) [Gal(1-3)]Gal(1-3)[Fuc(1-4)]Glc, was based on the results of methylation analysis and¹H/¹³C-NMR spectroscopy.Abbreviations HPLC high performance liquid chromatography - GLC gas liquid chromatography - NMR nuclear magnetic resonance - COSY correlation spectroscopy - Gal d-galactopyranose - GalNAc 2-acetamido-2-deoxy-d-galactopyranose - Glc d-glucopyranose - Fuc l-fucopyranose - LNDFH I lacto-N-difucohexaose I (Le^b determinant     

Ion transport across leech integument

The dorsal skin of the leech Hirudo medicinalis was used for electrophysiological measurements performed in Ussing chambers. The leech skin is a tight epithelium (transepithelial resistance = 10.5±0.5 k· cm^-2) with an initial short-circuit current of 29.0±2.9 A·cm^-2. Removal of Na⁺ from the apical bath medium reduced short-circuit current about 55%. Ouabain (50mol·l^-1) added to the basolateral solution, depressed the short-circuit current completely. The Na⁺ current saturated at a concentration of 90 mmol Na⁺·l^-1 in the apical solution (K _M=11.2±1.8 mmol·l^-1). Amiloride (100 mol·l^-1) on the apical side inhibited ca. 40% of the Na⁺ current and indicated the presence of Na⁺ channels. The dependence of Na⁺ current on the amiloride concentration followed Michaclis-Menten kinetics (K _i=2.9±0.4 mol·l^-1). The amiloride analogue benzamil had a higher affinity to the Na⁺ channel (K _i=0.7±0.2 mol·l^-1). Thus, Na⁺ channels in leech integument are less sensitive to amiloride than channels known from vertebrate epithelia. With 20 mmol Na⁺·l^-1 in the mucosal solution the tissue showed an optimum amiloride-inhibitable current, and the amiloride-sensitive current under this condition was 86.8±2.3% of total short-circuit current. Higher Na⁺ concentrations lead to a decrease in amiloride-blockade short-circuit current. Sitmulation of the tissue with cyclic adenosine monophosphate (100 mol·l^-1) and isobutylmethylxanthine (1 mmol·l^-1) nearly doubled short-circuit current and increased amiloride-sensitive Na⁺ currents by 50%. By current fluctuation analysis we estimated single Na⁺ channel current (2.7±0.9 pA) and Na⁺ channel density (3.6±0.6 channels·m^-2) under control conditions. After cyclic adenosine monophosphate stimulation Na⁺ channel density increased to 5.4±1.1 channels·m^-2, whereas single Na⁺ channel current showed no significant change (1.9±0.2 pA). These data present a detailed investigation of an invertebrate epithelial Na⁺ channel, and show the similarities and differences to vertebrate Na⁺ channels. Whereas the channel properties are different from the classical vertebrate Na⁺ channel, the regulation by cyclic adenosine monophosphate seems similar. Stimulation of Na⁺ uptake by cyclic adenosine monophosphate is mediated by an increasing number of Na⁺ channels.Abbreviations slope of the background noise component - ADH antidiuretic hormone - cAMP cyclic adenosine monophosphate - f frequency - f _c coner frequency of the Lorentzian noise component - Hepes N-hydroxyethylpiperazine-N-ethanesulphonic acid - BMX isobutyl-methylxanthine - i _Na single Na⁺ channel current - I _Na max, maximal inhibitable Na⁺ current - I _SC short circuit current - K _i half maximal blocker concentration - K _M Michaelis constandard error of the mean - S _(f) power density of the Lorentzian noise component - S ₀ plateau value of the Lorentzian noise component - TMA tetramethylammonium - Trizma TRIS-hydroxymethyl-amino-methane - V _max maximal reaction velocity - V _T transepithelial potential - K half maximal blocker concentration     

Degradation of polyaromatic hydrocarbons by Burkholderia cepacia 2A-12

A new strain of bacterium degrading polyaromatic hydrocarbons (PAHs), Burkholderia cepacia 2A-12, was isolated from oil-contaminated soil. Of three PAHs, the isolated strain could utilize naphthalene (Nap) and phenanthrene (Phe) as a sole carbon source but not pyrene (Pyr). However, the strain could degrade Pyr when a cosubstrate such as yeast extract (YE) was supplemented. The PAH degradation rate of the strain was enhanced by the addition of other organic materials such as YE, peptone, glucose, and sucrose. YE was a particularly effective additive in stimulating cell growth as well as PAH degradation. When 1 g YE l^–1, an optimum concentration, was supplemented into the basal salt medium (BSM) with 215 mg Phe l^–1, the specific growth rate (0.30 h^–1) and Phe-degrading rate (29.6 mol l^–1 h^–1) were enhanced approximately ten and three times more than those obtained in the BSM with 215 mg Phe l^–1, respectively. Both cell growth and PAH degradation rates were increased with increasing Phe and Pyr concentrations, and B. cepacia 2A-12 had a tolerance against Phe and Pyr toxicity at the high concentration of 730–760 mg l^–1. Through kinetic analysis, the maximum specific growth rate ( _max) and PAH degrading rate ( _max) for Phe were obtained as 0.39 h^–1 and 300 mol l^–1 h^–1, respectively. Also, _max and _max for Pyr were 0.27 h^–1 and 52 mol l^–1 h^–1, respectively. B. cepacia 2A-12 could simultaneously degrade crude oil as well as PAHs, indicating that this bacterium is very useful for the removal of oils and PAHs contaminants.     

Ethanol production in multistage continuous, single stage continuous, Lactobacillus-contaminated continuous, and batch fermentations

Saccharomyces cerevisiae-based ethanol fermentations were conducted in batch culture, in a single stage continuous stirred tank reactor (CSTR), a multistage CSTR, and in a fermentor contaminated with Lactobacillus that corresponded to the first fermentor of the multistage CSTR system. Using a glucose concentration of 260 g l^–1 in the medium, the highest ethanol concentration reached was in batch (116gl^–1), followed by the multistage CSTR (106gl^–1), and the single stage CSTR continuous production system (60gl^–1). The highest ethanol productivity at this sugar concentration was achieved in the multistage CSTR system where a productivity of 12.7gl^–1h^–1 was seen. The other fermentation systems in comparison did not exceed an ethanol productivity of 3gl^–1h^–1. By performing a continuous ethanol fermentation in multiple stages (having a total equivalent working volume of the tested single stage), a 4-fold higher ethanol productivity was achieved as compared to either the single stage CSTR, or the batch fermentation.     

Activation of fatty acids by non-glyoxysomal peroxisomes

Ethylene treatment (approx. 20 l ·1^-1 in air for 2 d) of tobacco (Nicotiana tabacum L. cv. Havana 425) plants markedly increases the endo--1,3-glucanase (EC 3.2.1.39) content of leaves. The antigenic form of the enzyme induced is the same one whose production is blocked by treating cultured cells with combinations of auxin (1.1 · 10^-5 M -naphthaleneacetic acid) and cytokinin (1.4 · 10^-6 M kinetin). Evidence is presented that cultured tobacco cells require ethylene for -1,3-glucanase accumulation: i) ethylene treatment increased the accumulation of \-1,3-glucanase in callus tissues >10 d after subculturing and in cell-suspension cultures; ii) callus tissues can produce ethylene; iii) conditions known to inhibit ethylene production (1 mM CoCl₂; 33° C treatment) or ethylene action (approx. 1.6 mmol · 1^-1 norbornadiene in air) inhibited -1,3-glucanase accumulation by callus tissues treated for 4 d following subculturing; and, these inhibitory effects were prevented by exogenous ethylene. Combinations of auxin and cytokinin blocked ethylene-induced accumulation of -1,3-glucanase by cell-suspension cultures. The results favor a model in which ethylene induces results favor a model in which ethylene induces 1,3-glucanase accumulation, and auxin and cytokinin inhibit this induction process.Abbreviations NAA -naphthaleneacetic acid - NDE norbornadiene     

Somatic embryogenesis in callus cultures of Rosa hybrida L. cv. Landora

Callus was initiated from immature leaf and stem segments of rose (Rosa hybrida cv. Landora) and subcultured every four weeks on a basal medium of half-strength Murashige & Skoog (1962) salts plus 30 g l^-1 sucrose (1/2 MS) and supplemented with 2.2 M BA, 5.4 M NAA and 2.2–9.0 M 2,4-D. Embryogenic callus and subsequently somatic embryos were obtained from 8-week-old callus culture on 1/2 MS+2.2 M BA+0.05 M NAA+0.3 M GA₃+200–800 mg l^-1 L-proline. Long-term cultures were established and maintained for up to 16 months by repeated subculture of embryogenic callus on L-proline deficient medium. About 12% of cotyledonary stage embryos taken from cultures cold-stored at 8±1°C for 4 days germinated on 1/2 MS+2.2 M BA+0.3 M GA₃+24.7 M adenine sulphate.Abbreviations BA benzyladenine - NAA -naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid     

Ecotoxicity of lead to the zebra musselDreissena Polymorpha,Pallas

The effect of lead on the filtration rate of the zebra musselDreissena polymorpha was investigated, together with the accumulation of Pb in the soft tissues of the mussels. The NOEC-filtration was 116 g.l^–1 (0,56 mol.l^–1) and the EC₅₀-filtration was 370 g.l^–1 (1.79 mol.l^–1). The NOEC-accumulation was the concentration found in the control water (1.4g.l^–1). These experiments show that the EC₅₀-filtration for Pb is similar to that for Cd, higher than that for Cu and lower than that for Zn. The water quality criteria for lead allow 25 g Pb.l^–1 in surface water. This will not cause short-term effects. Long-term effects may, however, occur, since an accumulation of Pb as low as 16 g.l^–1 was recorded in this study.     

Specific Cd2+ uptake of encapsulated Aureobasidium pullulans biosorbents

Calcium alginate capsules containing Aureobasidium pullulans cells were prepared by an in-situ one-step method. The Cd²⁺uptakes of free biosorbent and capsule biosorbent were described well by the Freundlich isotherms. The Cd²⁺ uptake of capsule biosorbent was lower than that of free biosorbent with Cd^{2 +}at 100 mg l^–1. The total cadmium uptake of capsule biosorbent increased with the increase in encapsulated cell density and plateaued at a value of 23 g Cd²⁺/capsule with 150 g dry biosorbent l^–1 core volume of a capsule. The specific cadmium uptake of encapsulated biosorbent was 85% to that of free biosorbent at 35 g biosorbent dry weight l^–1 core volume of a capsule, decreased to 35% at 176 g biosorbent dry weight l^–1.     

Inversion of gravitropism by symmetric blue light on the clinostat

Gravitropic stimulation of maize (Zea mays L.) seedlings resulted in a continuous curvature of the coleoptiles in a direction opposing the vector of gravity when the seedlings were rotated on a horizontal clinostat. The orientation of this response, however, was reversed when the gravitropic stimulation was preceeded by symmetric preirradiation with blue light (12.7 mol photons·m^–2). The fluence-response curve of this blue light exhibited a lower threshold at 0.5 mol·m^–2, and could be separated into two parts: fluences exceeding 5 mol·m^–2 reversed the direction of the gravitropic response, whereas for a range between the threshold and 4 mol·m^–2 a split population was obtained. In all cases a very strong curvature resulted either in the direction of gravity or in the opposite orientation. A minor fraction of seedlings, however, curved towards the caryopsis. Furthermore, the capacity of blue light to reverse the direction of the gravitropic response disappeared with the duration of gravitropic stimulation and it depended on the delay time between both stimulations. Thistonic blue-light influence appears to be transient, which is in contrast to the stability observed fortropistic blue-light effects.This work was supported by the Deutsche Forschungsgemeinschaft.