Toxicity of chromium to the marine planktonic copepodAcartia clausi,Giesbrecht

The toxicity of chromium to the marine planktonic copepodAcartia clausi, Giesbrecht was studied. The LC50 48 h values (concentration of chromium lethal to 50% of the test animals) vary with the experimental temperature, the form of chromium compound tested and the annual generation to which theAcartia specimens belong. The elevation of temperature resulted in a considerable increase ofAcartia's sensitivity to chromium. Cr⁶⁺ in the form of Na₂CrO₄ was more toxic toA. clausi than in the form of CrO₃ · Cr³⁺ in the form of Cr(NO₃)₃ 9 H₂O precipitated to the bottom and was not toxic toAcartia.Acartia specimens belonging to the summer generation were more sensitive to chromium than those belonging to the winter or autumn generation. The exposure ofAcartia to sublethal concentrations of chromium resulted in a reduction of its longevity proportional to the chromium concentrations used.Furthermore, whenA. clausi was exposed to sublethal chromium concentrations it showed a decrease of feeding capacity and increase of respiratory rates, which became more pronounced with increasing chromium concentrations.     

Biosorption of heavy metal ions by brown seaweeds from southern coast of Korea

Heavy metal ions (Pb²⁺, Cd²⁺, Mn²⁺, Cu²⁺, and Cr₂O₇ ^2?) were biosorbed by brown seaweeds (Hizikia fusiformis, Laminaria japonica, and Undaria pinnatifida) collected from the southern coast of South Korea. The biosorption of heavy metal ions was pH-dependent showing a minimum absorption at pH 2 and a maximum biosorption at pH 4 (Pb²⁺, Cd²⁺, Mn²⁺, and Cr₂O₇ ^2?) or pH 6 (Cu²⁺). Biosorption increased most noticeably for pH changes from 2 to 3. In the latter pH range, biosorption increased, because a higher pH decreased the electrostatic repulsion between metal ions and functional groups on the seaweed. In the pH range of 2 ～ 4, biosorption of negatively-charged chromium species (Cr₂O₇ ^?2) followed the pattern of positively-charged metal ions (Pb²⁺, Cd²⁺, Mn²⁺, and Cu²⁺). This suggests that the most prevalent chromium species were positively-charged Cr³⁺, reduced from Cr⁶⁺ in Cr₂O₇ ^?2. Whereas positively-charged heavy metal ions (Pb²⁺, Cd²⁺, Mn²⁺, and Cu²⁺) reached a plateau after the maximum level, biosorption of chromium ions decreased noticeably between pH 5 and 8. Kinetic data showed that biosorption by brown seaweed occurred rapidly during the first 10 min, and most of the heavy metals were bound to the seaweed within 30 min. Equilibrium adsorption data for a lead ion could fit well in the Langmuir and Freundlich isotherm models with regression coefficients (R ²) between 0.93 and 0.98.     

Chromate reduction by <Emphasis Type="Italic">Bacillus megaterium</Emphasis> TKW3 isolated from marine sediments

Summary Bacillus megaterium strain TKW3 was isolated from multiple-metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. This facultative aerobe utilized arabinose, mannitol, N-acetylglucosamine, maltose, caprate, citrate, butyrate or lactate as the sole source of carbon and energy for growth.B. megaterium TKW3 reduced highly toxic and soluble Cr⁶⁺ (as CrO₄²⁻) into almost non-toxic and insoluble Cr³⁺ under aerobic conditions. Complete reduction of 0.20 mM Cr⁶⁺ by B. megaterium TKW3 was achieved within 360 h. Initial Cr⁶⁺ concentration below 0.90 mM or inoculum less than 10⁷ cells ml⁻¹ did not have significant effect on ⁶⁺ reduction, while the residue Cr⁶⁺ concentration was the lowest at 10⁷ cells ml⁻¹. Cr⁶⁺ reduction by this strain was inhibited by high levels of NaCl (55%). B. megaterium TKW3 was also resistant to other oxyanions including 0.34 mM Cr₂O₇²⁻ 0.32 mM AsO₄³⁻, 0.58 mM SeO₃²⁻ and 0.53 mM SeO₄²⁻, and reduced soluble Se⁴⁺ (as SeO₃²⁻) to insoluble red amorphous Se⁰. B. megaterium TKW3 might have potential application in bioremediation of Cr-laden sediments associated with other oxyanions.     

Effect of different oxidation states of chromium in causing chromosome alterations in cultured CHO cells

Four chromium salts with different oxidation states were tested for their influence in causing chromosome aberrations and sister-chromatid exchange in Chinese hamster ovary cellsin vitro. Cell cultures were treated with CrO₃, K₂Cr₂O₇, CrCl₂ and Cr(NO₃)₃.9H₂O at concentrations of 10^–7, 10^–6, 10^–5 and 10^–4 M for the aberration assay, and 10^–8, 10^–7, 10^–6 and 10^–5 M for the sister-chromatid exchange assay. It was noticed that Cr (VI) compounds-CrO₃ and K₂Cr₂O₇-considerably enhanced the frequencies of aberrations and sister-chromatid exchanges compared to the control cultures. CrCl₂ and Cr(NO₃)₃.9H₂O–Cr (II) and Cr (III) respectively-caused a slight increase in sister-chromatid exchange rates, but the frequencies of aberrations were almost unchanged compared to the controls. These investigations indicate a definite link between the metals and changes produced in the mammalian chromosomes, reaffirming the evidence of carcinogenic potential of Cr (VI) observed by other investigators.Abbreviations BrdU 5-bromo-2-deoxyuridine - CHO Chinese hamster ovary - SCE sister-chromatid exchange     

Effects of chromium VI stress on photosynthesis,chlorophyll integrity,cell viability,and proline accumulation in lichen <Emphasis Type="Italic">Ramalina farinacea</Emphasis>

In order to contribute to understanding of the response to metal stress, Ramalina farinacea (L.) Ach. was treated with different concentrations of chromium (VI) (5, 15, and 30 mM of K₂CrO₄) for 1, 3, and 24 h, and alterations in the photosystem II photosynthetic quantum yield, pigment content, integrity of chlorophyll, cell viability, and proline accumulation were investigated. Significant alterations of the photosynthetic quantum yield (F _v/F _m) ratio were observed in response to the increase in chromium concentration. The F _v/F _m ratio decreased in R. farinacea following 24-h treatment with 30 mM Cr⁶⁺ solution. In present study, in both control and other plant groups treated with 5 mM Cr⁶⁺, the Chl a/b ratio was approximately within the range of 2.0–3.5. However, this ratio significantly decreased for the samples treated with 15 (exposure period of 24 h) and 30 mM; (exposure periods of 3 and 24 h) Cr⁶⁺. We also showed that cell viability of samples treated with 15 and 30 mM Cr⁶⁺ significantly decreased. Accumulation of metal resulted in proline accumulation in R. farinacea thalli; however, when photodestructive effects on photosystem II occurred, proline intracellular concentration declined. On the basis of these results, we suggest that proline accumulation might not be the stress marker during heavy metal stress.     

Competitive adsorption of Pb, Cd and Zn ions onto Eichhornia crassipes in binary and ternary systems

A batch sorption technique was used to study the biosorption of Pb²⁺, Cd²⁺ and Zn²⁺ ions onto the vastly abundant water hyacinth weed, Eichhornia crassipes biomass in binary and ternary systems at a temperature of 30 °C and pH 4.84. Mutual interference effects were probed using equilibrium adsorption capacity ratios, , where the prime indicates the presence of one or two other metal ions. The combined action of the metals was found to be antagonistic, and the metal sorption followed the order Pb²⁺  Cd²⁺  Zn²⁺. The behaviour of competitive biosorption for Pb–Cd and Pb–Zn combinations were successfully described by the Langmuir Competitive Model (CLM), whilst the model showed poor fitting to the Cd–Zn data. In conclusion, Pb²⁺ ions could still be effectively removed from aqueous solution in the presence of both Cd²⁺ and Zn²⁺ ions, but removal of the Cd²⁺ and Zn²⁺ ions would be suppressed in the presence of Pb²⁺.     

Phenotypic expression of Vogesella indigofera upon exposure to hexavalent chromium,Cr6+

A eubacterium producing a blue pigment was isolated from a drinking water filter, and subsequently identified as Vogesella indigofera. This bacterium was further investigated for its morphological and biochemical characteristics after exposure to hexavalent chromium, Cr⁶⁺. The threshold Cr⁶⁺ concentration inhibiting the pigment production by V. indigofera was 200–300 g ml^–1 in liquid cultures of nutrient broth and 100–150 g ml^–1 on nutrient agar plates. The Cr⁶⁺ concentration preventing V. indigofera growth was 300–400 g ml^–1 in liquid cultures, but greater than 150 g ml^–1 on agar plates. Moreover, rugose colonies without the blue pigmentation were observed on agar plates amended with 150 (g Cr⁶⁺) ml^–1. The biochemical utilization profiles of the colonies without pigmentation did not differ from the original pigment-producing ones, indicating phenotypic plasticity of this bacterium. The difference of phenotypic expression of V. indigofera under various Cr⁶⁺ concentrations might have potential application as a pollution bioindicator for heavy metals.     

Cadmium biosorption by a cadmium resistant strain of Bacillus thuringiensis: regulation and optimization of cell surface affinity for metal cations

A marine bacterial strain putatively identified asBacillus thuringiensis strain DM55, showed multiple heavy metal resistance and biosorption phenotypes. Electron microscopic studies revealed that DM55 cells are encased in anionic cell wall polymers that can immobilize discrete aggregates of cations. Factors affecting cell surface affinity for metal cations, monitored by means of Cd²⁺ binding capability, are investigated. The mechanisms of cadmium resistance and Cd²⁺ biosorption by the bacterium appeared to be inducible and coincident. Medium components affecting metal removal under cadmium-stressed growth conditions were explored based on the application of two sequential multi-factorial statistical designs. Concentrations of potassium phosphates and peptone were the most significant variables. Optimized culture conditions allowed DM55 cells grown in the presence of 0.25 mM CdCl₂ to remove about 79% of the metal ions within 24 h with a specific biosorption capacity of 21.57 mg g^–1 of biomass. Both fresh and dry cells of DM55 prepared under cadmium-free optimal nutrient condition were also able to biosorb Cd²⁺. In addition to the concentration of phosphate in the medium, KinA, a major phosphate provider in the phosphorelay of Bacillus cells, was also demonstrated to regulate the magnitude of cell surface affinity for cadmium ions.     

Chromium uptake and transport in barley seedlings (Hordeum vulgare L.)

Summary Potassium chromate is more toxic to the growth of barley in solution culture than chromic chloride, though apparent uptake of the latter is much faster. Inhibitor studies indicate that CrO₄ ^2- uptake is active whereas Cr³⁺ uptake is passive, demonstrating that the two forms do not share a common uptake mechanism. Studies on the form of Cr inside root cells show that in plants fed CrO₄ ^2- the Cr remains largely unchanged whereas in plants fed Cr³⁺ a little CrO₄ ^2- (0.5 per cent) is produced. This conversion is dependent on the presence of living material and is probably enzymatic. Chromate uptake follows Michaelis-Menten kinetics at low concentration and is competitively inhibited by sulphate. Transport of chromium up the root is very slow, accounting for the low levels of Cr in the shoots. Chromate is transported better than Cr³⁺ though still to a very limited extent. These experiments provide a physiological basis for previous observations.     

Repeated removal of cadmium and zinc from an industrial effluent by waste biomass Sargassum sp.

Waste biomass Sargassum sp. biosorbed 100% of Cd²⁺ and 99.4% of Zn²⁺ from a 3 and 98 mg l^–1 solution (pH 4.5), respectively, at the end of four serial experiments. Of the five desorbents studied in consecutive adsorption/desorption cycles, CaCl₂ 0.05 M eluted nearly 40% of both metals and decreased the biosorption in only 8% and 17% of Cd²⁺ and Zn²⁺, respectively. Although NaOH desorbent improved the heavy metal uptake from the second cycle onwards, it did not elute metals from the pre-loaded biomass.     

Biosorptive removal of chromium by husk of Lathyrus sativus: Evaluation of the binding mechanism,kinetic and equilibrium study

The adsorption of tri‐ and hexavalent chromium by the husk of Lathyrus sativus (HLS), which is an agro‐waste has been investigated to find a potential solution to environmental pollution. The pH‐dependent adsorption process finds the optimum values for trivalent and hexavalent chromium ions at about pH 5.0 and pH 2.0, respectively. The process is very fast initially and attains an equilibrium within 90 min following pseudo second‐order rate kinetics. Equilibrium adsorption data can best elucidated by the Langmuir–Freundlich dual model (r² = 0.998) in comparison with other isotherm models examined indicating that both physi‐ and chemisorption are components of the binding mechanism of chromium ions on HLS. The results show that one gram of HLS can adsorb 24.6 mg Cr³⁺ and 44.5 mg Cr⁶⁺. Fourier transform infrared data and functional group modification experiments indicate that –NH₂, ‐COOH, ‐OH, ‐PO₄^3? groups of the biomass interact chemically with the chromium ions. SEM‐energy dispersive X‐ray analysis and X‐ray diffraction spectrum analysis were used to further assess the morphological changes and the mechanisms of chromium ion interaction with HLS. The analysis signified that the biosorption process involved surface morphological changes, complexation and an ion exchange mechanism. The amorphous nature of HLS facilitating metal biosorption was indicated by the X‐ray diffraction analysis.     

Wall appositions induced by ionophore A 23187, CaCl2, LaCl3, and nifedipine in characean cells

Summary The formation of wall appositions (plugs) by ionophore A 23187, CaCl₂, LaCl₃, and nifedipine was studied in mature internodal cells of characeaen algae. CaCl₂ at concentrations above 10^–2M induces thick fibrillar plugs without callose inNitella flexilis. InChara corallina andNitella flexilis ionophore A 23187 (1.25×10^–5 to 5×10^–5M) and LaCl₃ (7.5×10^–5 to 2.5×10^–4M) cause flat appositions which contain callose and have a more granular structure. Plug formation by ionophore A 23187, CaCl₂, and LaCl₃ is pH-dependent and occurs beneath the alkaline regions of the cell. Nifedipine (10^–4 to 10^–5M) induces plugs inNitella flexilis after previous injury. These callose-containing wall appositions consist of a heterogeneous granular core which is covered by a fibrillar layer. The results of this work are compared with previous studies on wound wall formation and chlortetracycline (CTC)-induced plug formation which reveal that abundant coated vesicles occur only when a thick fibrillar wall layer is formed. Neither LaCl₃ nor nifedipine inhibit the formation of CaCl₂- or CTC-plugs. The unusual effects of these substances, which normally act as Ca²⁺ antagonists and therefore should prevent and not induce plug formation, are discussed. It is suggested that La³⁺ mimicks the effects of calcium and that nifedipine binding to the Ca²⁺ channels is altered in the alkaline regions of characean internodes and allows an influx of Ca²⁺.Abbreviations AFW artificial fresh water - CTC chlortetracycline - DCMU dichlorphenyldimethylurea - DMSO dimethylsulfoxide - EGTA ethyleneglycoltetraacetic acid - MES 2-(N-morpholino) ethanesulfonic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - TAPS N-tris[hydroxymethyl]methyl-3-aminopropanesulfonic acid     

Removal of Cr(VI) from ground water by Saccharomyces cerevisiae

Chromium can be removed from ground water by the unicellular yeast, Saccharomyces cerevisiae. Local ground water maintains chromium as CrO₄ ^2- because of bicarbonate buffering and pH and E _h conditions (8.2 and +343 mV, respectively). In laboratory studies, we used commercially available, nonpathogenic S. cerevisiae to remove hexavalent chromium [Cr(VI)] from ground water. The influence of parameters such as temperature, pH, and glucose concentration on Cr(VI) removal by yeast were also examined. S. cerevisiae removed Cr(VI) under aerobic and anaerobic conditions, with a slightly greater rate occurring under anaerobic conditions. Our kinetic studies reveal a reaction rate (V_max) of 0.227 mg h^-1 (g dry wt biomass)^-1 and a Michaelis constant (Km) of 145 mg/l in natural ground water using mature S. cerevisiae cultures. We found a rapid (within 2 minutes) initial removal of Cr(VI) with freshly hydrated cells [55–67 mg h^-1 (g dry wt biomass)^-1] followed by a much slower uptake [0.6–1.1 mg h^-1 (g dry wt biomass)^-1] that diminished with time. A materials-balance for a batch reactor over 24 hours resulted in an overall shift in redox potential from +321 to +90 mV, an increase in the bicarbonate concentration (150–3400 mg/l) and a decrease in the Cr(VI) concentration in the effluent (1.9-0 mg/l).     

Use of ascorbic acid in the51Cr labelling of mouse fibrosarcoma cells

Summary We have studied and discussed the significance of the use of ascorbic acid in⁵¹Cr labelling of cells. The following two advantages seem credible if cells (mouse fibrosarcoma) in culture are incubated for about 2 h in a medium containing Na₂ ⁵¹CrO₄ and then ascorbic acid is added to the medium and incubation continued for ten more minutes:(a) the natural intracellular conversion of Cr⁶⁺ to Cr³⁺ appears to be aided,(b) the incorporation of chromium by cells is higher.     

Bacterial Reduction of Hexavalent Chromium: Kinetic Aspects of Chromate Reduction by Enterobacter cloacae HO1

Kinetic aspects of the bacterial reduction of hexavalent chromium (chromate: CrO^2-₄) were investigated using Enterobacter cloacae strain HO1. E. cloacae strain HO1 could reduce hexavalent chromium to the trivalent form (Cr³⁺) anaerobically. High concentrations of CrO^2-₄ inhibited the reduction, and a substrate inhibition model gave a good fit to the observed data. The rate of chromate reduction was proportional to cell density. The effect of temperature on the reduction rate followed the Arrhenius equation. The rate of chromate reduction was also dependent on pH and the concentrations of carbon and energy sources in the culutre medium. Amino acids including asparagine, methionine, serine and threonine were utilized effectively as carbon and energy sources for chromate reduction.     

Nitrogen and phosphorus uptake by the Brazilian kelp Laminaria abyssalis (Phaeophyta) in culture

The uptake of ammonium, nitrate and phosphate by laboratory-grown young sporophytes of Laminaria abyssalis was measured in a perturbed system (batch mode) at 18 °C and 35 ± 5 µE m^–2 s^–1 photon flux density. Uptake of all appeared to follow saturation-type nutrient uptake kinetics. The NO _inf3 ^sup– (K _s = 14.0 µM, V _max = 5.0 µmol h^–1 g^–1 dry wt) and NH _inf4 ^sup+ (K _s = 4.6 µM, V _max= 2.0 µmol h^–1 g^–1 dry wt) were taken up simultaneously, although NH _inf4 ^sup+ was taken up more rapidly. Values of K ₃ and V _max for phosphate were, respectively, 2.21 µM and 0.83 µmol h^–1 g^–1 dry wt. Nitrate and phosphate were both consumed in similar rates (V _max /Ks 0.37) at low concentrations. NH _inf4 ^sup+ , thus, might be a more efficient form of N fertilizer if artificial enrichment of seawater is used.     

Screening yeast cells for absorption of selenium oxyanions

Certain yeast cells on solid nutrient medium produced colonies surrounded by a light zone of selenite absorption. This screening procedure resulted in the selection of 22 strains out of 200 isolates with different Se⁴⁺-absorbing capacity ranging from 16 to 98.8 g Se⁴⁺ g^–1 l^–1 h^–1. The highest rate of Se⁴⁺ elimination from the Na₂SeO₃ solution was observed with an oval shaped, cream pigmented fermentative yeast, tentatively called Candida sp. strain MS4. This strain was isolated from wastewater and found to accumulate selenium oxyanions. Se⁴⁺ uptake involved both inactive and active phenomena. The amounts of selenium (initial concentration 2 mg Se⁴⁺ l^–1) removed from aqueous solution by inactive and active phenomena were 667 g Se⁴⁺ g^–1 l^–1, and 1580 g Se⁴⁺ g^–1 l^–1, respectively. The strain also removed selenate inactively (135 g Se⁶⁺ g^–1 l^–1).     

Ulva rigida (Ulvales,Chlorophyta) tank culture as biofilters for dissolved inorganic nitrogen from fishpond effluents

Ulva rigida was cultivated in 7501 tanks at different densities with direct and continuous inflow (at 2, 4, 8 and 12 volumes d^–1) of the effluents from a commercial marine fishpond (40 metric tonnes, Tm, of Sparus aurata, water exchange rate of 16 m³ Tm^–1) in order to assess the maximum and optimum dissolved inorganic nitrogen (DIN) uptake rate and the annual stability of the Ulva tank biofiltering system. Maximum yields (40 g DW m^–2 d^–1) were obtained at a density of 2.5 g FW 1^–1 and at a DIN inflow rate of 1.7 g DIN m^–2 d^–1. Maximum DIN uptake rates were obtained during summer (2.2 g DIN M^–2 d^–1), and minimum in winter (1.1 g DIN m^–2 d^–1) with a yearly average DIN uptake rate of 1.77 g DIN m^–2 d^–1 At yearly average DIN removal efficiency (2.0 g DIN m^–2 d^–1, if winter period is excluded), 153 m² of Ulva tank surface would be needed to recover 100% of the DIN produced by 1 Tm of fish.Abbreviations DIN= dissolved inorganic nitrogen (NH _inf4 ^sup+ + NO _inf3 ^sup– + NO _inf2 ^sup– ); - FW= fresh weight; - DW= dry weight; - PFD= photon flux density; - V= DIN uptake rate     

A quantitative appraisal of the ambivalent metal ion binding properties of cytidine in aqueous solution and an estimation of the<Emphasis Type="Italic"> anti</Emphasis>–<Emphasis Type="Italic">syn</Emphasis> energy barrier of cytidine derivatives

The recently defined versus straight-line plots for L = pyridine-type (PyN) and ortho-aminopyridine-type (oPyN) ligands now allow the evaluation in a quantitative manner of the stability of the 1:1 complexes formed between cytidine (Cyd) and Ca²⁺, Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ or Cd²⁺ (M²⁺); the corresponding stability constants, , including the acidity constant, , for the deprotonation of the (N3)H⁺ site had been determined previously under exactly the same conditions as the mentioned plots. Since the stabilities of the M(PyN)²⁺ and M(oPyN)²⁺ complexes of Ca²⁺ and Mg²⁺ are practically identical, it is concluded that complex formation occurs in an outer-sphere manner, and this is in accord with the fact that in the pK_a range 3–7 metal ion binding is independent of or . Ca(Cyd)²⁺ and Mg(Cyd)²⁺ are more stable than the corresponding (outer-sphere) M(PyN)²⁺ complexes and this means that the C2 carbonyl group of Cyd must participate, next to N3 which is most likely outer-sphere, in metal ion binding, leading thus to chelates; these have formation degrees of about 50% and 35%, respectively. Co(Cyd)²⁺ and Ni(Cyd)²⁺ show no increased stability based on the hence, the (C2)O group does not participate in metal ion binding, but the inner-sphere coordination to N3 is strongly inhibited by the (C4)NH₂ group. In the M(Cyd)²⁺ complexes of Mn²⁺, Cu²⁺, Zn²⁺ and Cd²⁺, this inhibiting effect on M²⁺ binding at N3 is partially compensated by participation of the (C2)O group in complex formation and the corresponding chelates have formation degrees between about 30% (Zn²⁺) and 83% (Cu²⁺). The different structures of the mentioned chelates are discussed in relation to available crystal structure analyses. (1) There is evidence (crystal structure studies: Cu²⁺, Zn²⁺, Cd²⁺) that four-membered rings form, i.e. there is a strong M²⁺ bond to N3 and a weak one to (C2)O. (2) By hydrogen bond formation to (C2)O of a metal ion-bound water molecule, six-membered rings, so-called semichelates, may form. (3) For Ca²⁺ and Mg²⁺, and possibly Mn²⁺, and their Cyd complexes, six-membered chelates are also likely with (C2)O being inner-sphere (crystal structure) and N3 outer-sphere. (4) Finally, for these metal ions also complexes with a sole outer-sphere interaction may occur. All these types of chelates are expected to be in equilibrium with each other in solution, but, depending on the metal ion, either the one or the other form will dominate. Clearly, the cytidine residue is an ambivalent binding site which adjusts well to the requirements of the metal ion to be bound and this observation is of relevance for single-stranded nucleic acids and their interactions with metal ions. In addition, the anti–syn energy barrier has been estimated as being in the order of 6–7.5 kJ/mol for cytidine derivatives in aqueous solution at 25 °C.Abbreviations ADP^3– adenosine 5-diphosphate - AMP^2– adenosine 5-monophosphate - ATP^4– adenosine 5-triphosphate - CDP^3– cytidine 5-diphosphate - cl closed - CMP^2– cytidine 5-monophosphate - 3-CMP^2– cytidine 3-monophosphate - CTP^4– cytidine 5-triphosphate - Cyd cytidine - DNA deoxyribonucleic acid - I ionic strength - K_a acidity constant - K_I intramolecular equilibrium constant - L general ligand - M²⁺ general divalent metal ion - NTP^4– nucleoside 5-triphosphate - op open - oPyN ortho-aminopyridine-type ligand - PyN pyridine-type ligand - t-RNA transfer ribonucleic acid - Tu tubercidin (7-deazaadenosine)In honor of Professor Liang-Nian Ji on the occasion of his 70th birthday in friendship and with best wishes.     

Protoplasmaresistenz von Meeresalgen und Meeresanthophyten gegen Schwermetallsalze

Zusammenfassung Es wurde die Resistenz des Plasmas von 14 Phaeophyceen, 32 Rhodophyceen, 17 Chlorophyceen und 3 Meeres-Phanerogamen durch Einlegen der Thalli 48 Stunden lang in konzentrationsabgestuften Lösungsreihen von MnSO₄, ZnSO₄, Cr₂(SO₄)₃, VOSO₄ und CuSO₄ (10^–6–1 Mol/L) ermittelt.Diese Resistenzgrenzen in den verschiedenen Lösungen von Mangan-, Zink-, Chrom-, Vanadyl- und Kupfersulfat ergeben für die einzelnen Meeresalgen charakteristische Resistenzkombinationen, die der Ausdruck konstitutioneller Unterschiede des Plasmas der einzelnen Algen sind. Die Resistenzkombinationen der untersuchten Meeresalgen decken sich im allgemeinen mit denen von Anthophyten.Alle von uns untersuchten Algen und Meeres-Phanerogamen sind durch eine hohe Resistenz gegen Mangansulfat, die Meeres-Phanerogamen auch gegen Zinksulfat ausgezeichnet.Das Protoplasma der meisten untersuchten Phaeophyceen und der drei Meeres-Phanerogamen weist gegen Mangansulfat die höchste Resistenz auf (1 Mol/L), während das Protoplasma der Rhodophyceen die geringste Resistenz besitzt (0,1–10^–2 Mol/L). Das Protoplasma der Chlorophyceen nimmt hinsichtlich der Resistenzgrenzen gegenüber Mangansulfat eine Stellung zwischen Phaeophyceen und Rhodophyceen ein.Die Resistenzgrenzen des Plasmas der untersuchten Meeresalgen gegen Zink-, Chrom-, Vanadyl- und Kupfersulfat liegen in niederen, hypotonischen Konzentrationen.Es ist zu vermuten, daß die Widerstandsfähigkeit gegen hypertonische Konzentrationen —wie bei uns in MnSO₄ — darauf beruht, daß auf dem Plasma eine irreversibel koagulierte Oberflächenschicht erzeugt wird, welche den Salzen ein weiteres Eindringen ins Binnenplasma verwehrt. Da bei niedrigeren, hypotonischen Konzentrationen — wie bei uns in ZnSO₄, Cr₂(SO₄)₃, VOSO₄ und CuSO₄ — diese Möglichkeit nicht gegeben ist, stirbt das Plasma ab, falls es nicht resistent ist.

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Protoplasmic resistances of marine algae and marine anthophytes to heavy metal salts

Summary Plasmatic resistances of 14Phaeophyceae, 32Rhodophyceae, 17Chlorophyceae, and 3 marine phanerogams were determined by immersion of thalli for 48 hours into concentration-graded solution series of MnSO₄, ZnSO₄, Cr₂(SO₄)₃, VOSO₄, and CuSO₄ (10^–6–1 mol/l).These limits of resistance in various solutions of manganese, zinc, chromium, vanadyl, and copper sulfates yield resistance combinations characteristic for the algal species, which are an expression of constitutional differences in the plasma of the algae tested. Resistance combinations of the marine algae investigated generally coincide with those of anthophytes. All the algae and marine phanerogams investigated by us are characterized by high resistance to manganese sulfate, the marine phanerogams also to zinc sulfate.The protoplasm of most of thePhaeophyceae investigated and of the three marine phanerogams shows the highest resistance to manganese sulfate (1 mol/l), whereas the protoplasm of theRhodophyceae is least resistant (10^–1–10^–2 mol/l). The protoplasm ofChlorophyceae occupies an intermediate position betweenPhaeophyceae andRhodophyceae in respect to the resistance limits.Plasmatic resistance limits to zinc, chromium, vanadyl, and copper sulfates of the marine algae investigated correspond to low, hypotonic concentrations.It may be guessed that the resistance to hypertonic concentrations—as, in our case, of MnSO₄—is due to the formation of an irreversibly coagulated surface layer, which prohibits the salts from entering the ground plasm. Since this possibility is absent in lower, hypotonic concentrations (as, in our experiments, in ZnSO₄, Cr₂(SO₄)₃, VOSO₄, and CuSO₄) the protoplasm is killed, provided it is not hardy.