Degradation of benzo(a)pyrene in Yangtze River source water with functional strains

Degradation of benzo(a)pyrene (BaP) existing in the Yangtze River, used as source water for Nanjing City, China, was investigated with functional strains. The removal rates of BaP were 37.5, 20.8 and 70.8% for the three strains of the native bacterium NJ, and the two functional strains of Xhhh and Fhhh, respectively. The Fhhh specific degradation rate of BaP was 3.02 × 10⁻⁶ day⁻¹, which was 1.9-fold of the rate with NJ and 3.7-fold of the rate with Xhhh. The concentrations of BaP in the source water, tap water and Fhhh reactor effluent were 8.3-, 7.6-, and 2.4-fold of that of the oral carcinogenicity unit risk. The results suggest that the functional strain Fhhh could be used for the reduction of BaP concentrations in source water and hence reduction of carcinogenic risk.     

Distribution and ecosystem risk assessment of polycyclic aromatic hydrocarbons in the Luan River,China

The distribution and ecosystem risk of 16 polycyclic aromatic hydrocarbons (PAHs) in the Luan River, China, has been investigated. ∑PAHs levels ranged from 37.3 to 234 ng L⁻¹ in water, from 20.9 to 287 ng g⁻¹ in sediment and from 36.9 to 378 ng g⁻¹ in bank soil, respectively. A method based on toxic equivalency factors (TEFs) and risk quotient (RQ) which can be used to assess the ecosystem risk of ∑PAHs sensitively and accurately was invented and a new ecosystem risk classification of ∑PAHs was suggested. The results indicated that the PAHs in aquatic environment of the Luan River resulted in low ecosystem risk and at S9 the ecosystem risk of PAHs in water was moderate. Low and moderate molecular PAHs presented much more ecosystem risk than high molecular PAHs in the Luan River basin and the mean ecosystem risk in water was higher than that in sediment and bank soil.     

Historical record and source apportionment of polycyclic aromatic hydrocarbons in the Lianhuan Lake sediments

Polycyclic aromatic hydrocarbons (PAHs) in a sediment core from the north Lianhuan Lake were collected to investigate its historical changes in the last one hundred years and its possible influence on ecological system in the lake. GC–MS was used to determine the concentrations of PAHs, and sediment chronological age was examined by ¹³⁷Cs dating approach. The concentrations of 16 different kinds of PAHs in the sediment samples ranged from 297 to 1,327 ng g⁻¹, and the low molecular weight (LMW) were predominant. The intensification of industrial and anthropogenic activities in the Daqing oil field may play the key role in the increase of PAHs concentrations in the late 1950s. To the early 1980s, the PAHs concentrations significantly decreased due to the grain size coarsening in the sediment samples, which was confirmed by the precipitation information. The 5–6 rings PAHs concentrations increased in the early 1980s may be attributed to the consumption of petroleum, coal and wood. The results showed that both the PAHs historical record and current concentrations may cause some influence on the Lianhuan Lake ecological system. The toxicology research on this ecological system should be done in the further investigations for determining the PAHs damage on human and ecological system health.     

Comparative toxicity of hydrophobic contaminants to microalgae and higher plants

To enable rapid and sensitive screening of phytotoxic compounds in terrestrial system, a 4 day solid-phase microalgal bioassay was developed. Three species of microalgae (Selenastrum capricornutum, Chlorococcum hypnosporum and Chlorococcum meneghini) were chosen to investigate their responses to DDTs (DDT, DDD and DDE) and PAHs (naphthalene, phenanthrene and pyrene) spiked sands. The bioassay results showed that PAHs and DDTs were toxic to microalgae in a 4-day exposure tests but not to seed germination of ryegrass (Lolium perenne). Phenanthrene was the most phytotoxic. Among three investigated endpoints, fluorescence emissions by microalgae were less sensitive than cell density (optical density OD₆₅₀) and chlorophyll a concentration as endpoints. In general, S. capricornutum was the most sensitive species for PAHs (EC₅₀ for phenanthrene = 9.4 mg kg⁻¹), while C. meneghini for DDTs (EC₅₀ for DDE = 20.0 mg kg⁻¹). Comparison of the microalgal tests with US EPA standard seed germination/root elongation test (using Lolium perenne) demonstrated the superior screening potential of phytotoxic hydrophobic compounds using the proposed bioassay. Using OD₆₅₀ as the endpoint, EC₁₀ of selected microalgae for PAHs and DDTs were 0.43–64.3 mg kg⁻¹ and 0.67–117 mg kg⁻¹ respectively, which were much lower than the EC₁₀ of L. perenne for both PAHs (94–187 mg kg⁻¹) and DDTs (113–483 mg kg⁻¹). The results encourage further studies involving wider types of vascular plants and more comparison with standard phytotoxicity tests from different authorities using contaminated soils to verify the effectiveness of the microalgal bioassay.     

Antimicrobial activity of isolate HL-12 against Clavibacter michiganensis subsp. michiganensis in the presence of cadmium

An actinomycete, strain HL-12, that was isolated from a farmland on the Huajiachi campus of Zhejiang University was capable of inhibiting the growth of Clavibacter michiganensis subsp. michiganensis (Cmm) and was identified as a member of Streptomyces. Its antimicrobial activity against Cmm was measured using the agar plate sensitivity method in pure culture and evaluated by the inhibition ratio of Cmm in soil. The inhibitory activity of strain HL-12 against Cmm following exposure to low concentrations of Cd was greater than the inhibitory activity following exposure to high concentrations of Cd both in liquid culture and in soil. A stronger inhibition was also seen following a 24 h preculture in the presence of Cd in liquid culture. The growth of Cmm in soil was stimulated at low concentrations of Cd (<5.0 mg Cd kg⁻¹ dry soil) but inhibited when cultured in high concentrations of Cd (5.0 and 10.0 mg Cd kg⁻¹ dry soil). A higher inhibition ratio of strain HL-12 against Cmm, which was over 40% after soil incubation for 2 weeks, was observed following exposure to low concentrations of Cd (<5.0 mg Cd kg⁻¹ dry soil).     

Toxicity of the amphoteric surfactant, cocamidopropyl betaine, to the marine macroalga, Ulva lactuca

The degradation of the synthetic, amphoteric surfactant, cocamidopropyl betaine (CAPB) and its toxicity to the marine macroalga, Ulva lactuca, has been evaluated using several different physiological test end-points over different periods of exposure up to 120 h. Droplet surface angle measurements revealed that, following a period of acclimation of about 24 h, CAPB began to degrade and that primary degradation was complete within 120 h. Effective quantum yield (∆F/F_m′) and relative growth rates (RGRs) were the most sensitive measures of phytotoxicity, with CAPB concentrations at and above 10 mg l⁻¹ eliciting irreversible, time-dependent and/or dose-dependent responses. Cell membrane damage, estimated from measurements of ion leakage, was detected only at a concentration of 40 mg l⁻¹ after 48 h of exposure to CAPB but by 120 h damage was evident at all measured concentrations above 10 mg l⁻¹. These observations suggest that both CAPB and its metabolites are intrinsically toxic to U. lactuca. The findings of this study are discussed in terms of the environmental consequences of applying CAPB to control harmful algal blooms.     

Dissolved organic carbon reduces uranium toxicity to the unicellular eukaryote <Emphasis Type="Italic">Euglena gracilis</Emphasis>

The influence of dissolved organic carbon (DOC), in the form of Suwannee River fulvic acid (SRFA), on uranium (U) toxicity to the unicellular eukaryote, Euglena gracilis (Z strain), was investigated at pH 6. In a background medium without SRFA, exposure of E. gracilis to 57 μg L⁻¹ U resulted in a 50% reduction in growth (IC₅₀). The addition of 20 mg L⁻¹ DOC (as SRFA), reduced U toxicity 4 to 5-fold (IC₅₀ increased to 254 μg L⁻¹ U). This reduction in toxicity was also evident at more sensitive effect levels with a 10% reduction in growth (IC₁₀) occurring at 5 μg L⁻¹ U in the background medium and at 17 μg L⁻¹ U in the SRFA medium, respectively. This amelioration of toxicity with the addition of SRFA was linked to a decrease in the bioavailability of U, with geochemical speciation modelling predicting 84% of U would be complexed by SRFA. The decrease in bioavailability of U in the presence of SRFA was also evident from the 11–14 fold reduction in the cellular concentration of U compared to that of E. gracilis in the background medium. Stepwise multiple linear regression analyses indicated that UO₂ ²⁺ alone explained 51% of the variation in measured U toxicity to E. gracilis. Preliminary U exposures to E. gracilis in the presence of a reactive oxygen species probe, suggest exposure to ≥60 μg L⁻¹ U may induce oxidative stress, but this endpoint was not considered to be a sensitive biological indicator.     

Involvement of Multidrug Resistance-Associated Protein 1 in Intestinal Toxicity of Methotrexate

Purpose  Methotrexate (MTX) causes dose-limiting gastrointestinal toxicity due to exposure of intestinal tissues, and is a substrate of the multidrug resistance-associated protein (MRP) 1. Here we examine the involvement of MRP1, which is reported to be highly expressed in the proliferative crypt compartment of the small intestine, in the gastrointestinal toxicity of MTX. Methods  MTX was intraperitonealy administered to mrp1 gene knockout (mrp1 ^(−/−)) and wild-type (mrp1 ^(+/+)) mice. Body weight, food and water intake were monitored, intestinal histological studies and pharmacokinetics of MTX were examined. Results   mrp1 ^(−/−) mice more severely decreased body weight, food and water intake than mrp1 ^(+/+) mice. Almost complete loss of villi throughout the small intestine in mrp1 ^(−/−) mice was observed, whereas the damage was only partial in mrp1 ^(+/+) mice. Plasma concentration and biliary excretion profiles of MTX were similar in mrp1 ^(−/−) and mrp1 ^(+/+) mice, though accumulation of MTX in immature proliferative cells isolated from mrp1 ^(−/−) mice was much higher compared to mrp1 ^(+/+) mice. Immunostaining revealed localization of Mrp1 in plasma membrane of the intestinal crypt compartment in mrp1 ^(+/+) mice, but not in mrp1 ^(−/−) mice. Conclusion  Mrp1 determines the exposure of proliferative cells in the small intestine to MTX, followed by gastrointestinal toxicity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effects of oil pollution at Kuwait’s greater Al-Burgan oil field on polycyclic aromatic hydrocarbon concentrations in the tissues of the desert lizard <Emphasis Type="Italic">Acanthodactylus scutellatus</Emphasis> and their ant prey

Using indicator species to monitor the effects of oil pollution was thought to be useful to assess whether local desert reptiles and their insect prey could fulfill such a role in an area damaged in the second Gulf War (1990). Polluted sites with apparently different degrees of contamination (namely tar mat, soot, and clear sites) located at Kuwait’s Greater Al-Burgan oil field were compared with control areas outside this region in study conducted in 2002. Five Acanthodactylus scutellatus lizards from each study and control site were humanely killed and stored in a freezer at −20°C until analysis. Ants from the same sites were also collected and treated in a similar manner. Lizard and ant whole body tissues were subjected to gas chromatography–mass spectrometry (GC–MS) to determine concentrations of petroleum hydrocarbons (HCs). The study concentrated on sixteen polycyclic aromatic hydrocarbons (PAHs), EPA priority pollutants used as indicators of petrogenic HC contamination. There were significantly different concentrations of total PAHs in lizards and ants among all four study sites. Of the 16 PAHs, phenanthrene, fluoranthene, and benzo[a]anthracene were present in both lizard and ant samples from the Greater Al-Burgan oil field sites irrespective of the apparent degree of pollution but were undetectable in materials from the control sites. The range of total PAHs in lizards was 26.5–301 ng g⁻¹ and it was 6.7–82.1 ng g⁻¹ in ants. Concentrations increased progressively along an expected contamination gradient. Total PAHs were detected in biota even in an area (clear site) that did not appear, virtually, to contain petroleum soil pollution which supports the value of indicator biota species. For all three sites where PAHs were found in biota, the ratio of total PAHs in ants to lizards was consistently 3.3–3.4. These data show that, although 12 years have passed since the Kuwait oil spill catastrophe, all sites are still contaminated with PAHs. Use of lizard and ant materials in monitoring such desert locations seems to be an effective strategy.     

Production of anatoxin-a by cyanobacterial strains isolated from Portuguese fresh water systems

The occurrence of anatoxin-a in several freshwater systems in Portugal and its production by Portuguese cyanobacterial strains, after cultivation in laboratory, were studied. Surface water samples from 9 water bodies, for recreational and human consumption usage, were surveyed for anatoxin-a presence and for obtaining cultures of pure cyanobacterial strains. Anatoxin-a analysis was performed by high performance liquid chromatography (HPLC) with fluorescence detection (FLD) followed by Mass Spectrometry (MS) confirmation. No anatoxin-a was detected in all the natural water samples (limit of detection (LOD) = 25 ng l⁻¹) but among the 22 isolated cyanobacterial strains, 13 could produce anatoxin-a in laboratory conditions (LOD = 3 ng g⁻¹ dw). This proportion of anatoxin-a producing strains (59.1%) in laboratory is discussed considering the hypothesis that anatoxin-a is a more frequent metabolite in cyanobacteria than it was thought before and making its occurrence in Portuguese freshwaters almost certain. Therefore, health and ecological risks caused by anatoxin-a in Portugal, should be seriously considered.     

Microbial transformation of aniline to acetaminophen

In order to obtain acetaminophen, a popular analgesic-antipyretic, through microbial p-hydroxylation and N-acetylation of aniline, various fungi and bacteria were screened. Among them,Streptomyces species were chosen for strain improvement by the use of interspecific protoplast fusion technique. Two interspecific fused strains were developed betweenS. rimosus (N-cetylation function) andS. aureofaciens (p-hydroxylation function) and also betweenS. lividans andS. globisporus. For efficient protoplast fusion and cell wall regeneration, various conditions were examined. In a typical experiment of mixedS. rimosus (pro⁻ his⁻) andS. aureofaciens (ilv⁻) protoplasts with 40% (w/v) polyethylene glycol 3350 (PEG) for 3 min gave 8.3×10⁻⁷ of fusion frequency. Treatment of mixedS. lividans (pant⁻) andS. globisporus (leu⁻) protoplasts with 50% (w/v) PEG for 3 min at 30°C gave 1.2×10⁻⁶ of frequency. Among the fused strains, up to 40–50% increase in p-hydroxylation power was observed. To investigate the possibility of plasmid involvement in p-hydroxylation of acetanilide, plasmid curing was attempted. We found that cells treated with acriflavine (at the frequency of 100%) and cells regenerated from protoplsts ofS. aureofaciens (2% frequency) lost their p-hydroxylation function.     

First report of anatoxin-a-producing cyanobacterium Aphanizomenon issatschenkoi in northeastern Germany

The neurotoxin anatoxin-a (ATX), has been detected in several northeast German lakes during the last two decades, but no ATX producers have been identified in German water bodies so far. In 2007 and 2008, we analyzed phytoplankton composition and ATX concentration in Lake Stolpsee (NE Germany) in order to identify ATX producers. Sixty-one Aphanizomenon spp. strains were isolated, morphologically and phylogenetically characterized, and tested for ATX production potential by liquid chromatography-tandem mass spectrometry (LC-MS/MS). New primers were specifically designed to identify a fragment of a polyketide synthase gene putatively involved in ATX synthesis and tested on all 61 Aphanizomenon spp. strains from L. Stolpsee and 92 non-ATX-producing Aphanizomenon spp., Anabaena spp. and Anabaenopsis spp. strains from German lakes Langersee, Melangsee and Scharmützelsee.As demonstrated by LC-MS/MS, ATX concentrations in L. Stolpsee were undetectable in 2007 and ranged from 0.01 to 0.12 μg l⁻¹ in 2008. Fifty-nine of the 61 strains isolated were classified as Aphanizomenon gracile and two as Aphanizomenon issatschenkoi. One A. issatschenkoi strain was found to produce ATX at concentrations of 2354 ± 273 μg g⁻¹ fresh weight, whereas the other A. issatschenkoi strain and A. gracile strains tested negative. The polyketide synthase gene putatively involved in ATX biosynthesis was found in the ATX-producing A. issatschenkoi strain from L. Stolpsee but not in the non-ATX-producing Aphanizomenon spp., Anabaena spp. and Anabaenopsis spp. strains from lakes Stolpsee, Langersee, Melangsee, and Scharmützelsee.This study is the first confirming A. issatschenkoi as an ATX producer in German water bodies.     

Suitability of <Emphasis Type="Italic">Daphnia similis</Emphasis> as an alternative organism in ecotoxicological tests: implications for metal toxicity

The acute toxicity of metals to Daphnia similis was determined and compared to other daphnid species to evaluate the suitability of this organism in ecotoxicology bioassays. To verify the performance D. similis in toxicity tests, we also investigated the effect of Pseudokirchneriella subcapitata at 1 × 10⁵ and 1 × 10⁶ cells ml⁻¹ on Cd and Cr acute toxicity to the cladoceran. Daphnid neonates were exposed to a range of chromium and cadmium concentrations in the absence and presence of the algal cells. Metal speciation calculations using MINEQL⁺ showed that total dissolved metal concentrations in zooplankton culture corresponded to 96.2% free Cd and 100% free Cr concentrations. Initial total dissolved metal concentrations were used for 48 h-LC₅₀ determination. LC₅₀ for D. similis was 5.15 × 10⁻⁷ mol l⁻¹ dissolved Cd without algal cells, whereas with 1 × 10⁵ cells ml⁻¹, it was significantly higher (7.15 × 10⁻⁷ mol l⁻¹ dissolved Cd). For Cr, the 48 h-LC₅₀ value of 9.17 × 10⁻⁷ mol l⁻¹ obtained for the cladoceran in tests with 1 × 10⁶ cells ml⁻¹ of P. subcapitata was also significantly higher than that obtained in tests without algal cells (5.28 × 10⁻⁷ mol l⁻¹ dissolved Cr). The presence of algal cells reduced the toxicity of metals to D. similis, as observed in other studies that investigated the effects of food on metal toxicity to standard cladocerans. Comparing our results to those of literature, we observed that D. similis is as sensitive to metals as other standardized Daphnia species and may serve as a potential test species in ecotoxicological evaluations.     

Tolerance and accumulation of lead by species of <Emphasis Type="Italic">Iris</Emphasis> L.

Seedling development, accumulation and distribution of lead (Pb) in Iris lactea var. chinensis (Fisch.) Koidz. and I. tectorum Maxim. were studied using plants grown in sand culture and exposed to 0–10 mmol l⁻¹ concentrations of Pb supplied as Pb(NO₃)₂ for 28 days. A significant reduction in dry weight (dw) of shoots and roots of I. lactea var. chinensis was observed at 6 and 10 mmol l⁻¹, respectively, and a significant reduction in dw of shoots and roots of I. tectorum was observed at 6 mmol l⁻¹. Concentration of Pb in the shoots and roots of I. lacteal var. chinensis exposed to 4 mmol l⁻¹ Pb reached 1,109 μg g⁻¹ and 2,408 μg g⁻¹ dw, respectively. The index of tolerance (IT) of I. lactea var. chinensis among 0–8 mmol l⁻¹ Pb treatments were not significantly different, while those of I. tectorum at 6 mmol l⁻¹ Pb were significantly decreased. The results indicated that I. lactea var. chinensis was more tolerant to Pb than I. tectorum. Sub-cellular localization of Pb in root cells was evaluated using transmission electron microscopy (TEM) and Pb deposits were found along the plasma membrane of some root tip cells of I. lactea var. chinensis treated at 10 mmol l⁻¹ Pb. Deposits of Pd were also observed along the surface, in the root tip cell wall and in the cytoplasm of a few malformed cells of I. tectorum exposed at 10 mmol l⁻¹ Pb treatment. One possible mechanism to explain these observations may be that most cells can maintain normal activities in the plant by sacrificing a small number of cells that accumulate a large amount Pb and show toxicity. Future studies should be designed to test this hypothesis.     

Acute and chronic effects of sodium and potassium on the tropical freshwater cladoceran <Emphasis Type="Italic">Pseudosida ramosa</Emphasis>

In this study, the toxicities of sodium and potassium to the tropical freshwater cladoceran Pseudosida ramosa were assessed. Acute toxicity tests on this species showed that the 48-h LC₅₀ of Na⁺ was 556 mg l⁻¹, while that of K⁺ was 17.7 mg l⁻¹. Long-term exposure of female P. ramosa to sodium reduced the total number of survivors from 10 to 6 at a concentration of 249 mg l⁻¹, 21-day fecundity from 20.4 to 14.3 eggs female⁻¹ at concentrations ranging from 72 to 249 mg l⁻¹, 21-day fertility from 20.1 to 6.5 neonates female⁻¹ at concentrations ranging from 25 to 249 mg l⁻¹. Furthermore, fecundity of each brood from the second to the fifth was significantly lower at 249 mg l⁻¹ and fertility of each brood from the first to the fifth at concentrations ranging from 25 to 249 mg l⁻¹. A significant decrease in fertility was associated with an increase in the number of aborted eggs. Long-term exposure to potassium decreased the 21-day fecundity of P. ramosa from 14.2 to 10.8 eggs female⁻¹ at a concentration of 11 mg l⁻¹ and fertility (fourth brood only) at 6.2 and 11 mg l⁻¹. Tropical reservoirs located near areas where the soil is overloaded with fertilizers and ferti-irrigation with vinasse already show concentrations of Na⁺ and K⁺ very close to those producing sub-lethal long-term effects on P. ramosa. A possible consequence is that organisms of the aquatic biota cannot adapt and freshwater taxa may become locally extinct, transferring dominance to salt-tolerant taxa.     

Change in life cycle parameters and feeding rate of <Emphasis Type="Italic">Ceriodaphnia silvestrii</Emphasis> Daday (Crustacea,Cladocera) exposure to dietary copper

Changes in life cycle parameters (survival, growth, reproduction) and feeding rate of the tropical cladoceran Ceriodaphnia silvestrii as affected by Cu contaminated algae Pseudokirchneriella subcapitata were investigated. The dietary copper exposure ranged from 3 × 10⁻¹⁵ to 68 × 10⁻¹⁵ g Cu algal cell⁻¹. Low waterborne copper exposure (around 10⁻¹⁰ mol l⁻¹ free Cu²⁺ ions) was kept in the experiments. The results show an increasing toxic effect on C. silvestrii with copper increase in algal cells; at the highest copper exposure, all life cycle parameters were significantly affected. A concentration of 38 × 10⁻¹⁵ g Cu algal cell⁻¹ reduced egg hatching percentile and the number of neonates produced per female, but did not cause any statistically significant effect on animals survival nor to the number of eggs produced per female. The following sequence of events was observed from the lowest to the highest copper contamination: reproduction, feeding rate, body length and, at last, survival was affected. We conclude that algal cells are an important route of copper exposure and toxicity to cladocerans.     

Feedback modeling of non-esterified fatty acids in rats after nicotinic acid infusions

A feedback model was developed to describe the tolerance and oscillatory rebound seen in non-esterified fatty acid (NEFA) plasma concentrations following intravenous infusions of nicotinic acid (NiAc) to male Sprague-Dawley rats. NiAc was administered as an intravenous infusion over 30 min (0, 1, 5 or 20 μmol kg⁻¹ of body weight) or over 300 min (0, 5, 10 or 51 μmol kg⁻¹ of body weight), to healthy rats (n = 63), and serial arterial blood samples were taken for measurement of NiAc and NEFA plasma concentrations. Data were analyzed using nonlinear mixed effects modeling (NONMEM). The disposition of NiAc was described by a two-compartment model with endogenous turnover rate and two parallel capacity-limited elimination processes. The plasma concentration of NiAc was driving NEFA (R) turnover via an inhibitory drug-mechanism function acting on the formation of NEFA. The NEFA turnover was described by a feedback model with a moderator distributed over a series of transit compartments, where the first compartment (M ₁) inhibited the formation of R and the last compartment (M _N ) stimulated the loss of R. All processes regulating plasma NEFA concentrations were assumed to be captured by the moderator function. The potency, IC ₅₀, of NiAc was 45 nmol L⁻¹, the fractional turnover rate k _out was 0.41 L mmol⁻¹ min⁻¹ and the turnover rate of moderator k _tol was 0.027 min⁻¹. A lower physiological limit of NEFA was modeled as a NiAc-independent release (k _cap ) of NEFA into plasma and was estimated to 0.032 mmol L⁻¹ min⁻¹. This model can be used to provide information about factors that determine the time-course of NEFA response following different modes, rates and routes of administration of NiAc. The proposed model may also serve as a preclinical tool for analyzing and simulating drug-induced changes in plasma NEFA concentrations after treatment with NiAc or NiAc analogues.     

The physiological response and sub-cellular localization of lead and cadmium in Iris pseudacorus L.

The seedling development and physiological responses of Iris pseudacorus L. to Pb and Cd and their combination were studied for 28 days liquid culture and sub-cellular localization of Pb and Cd in the root tip cells treated with 2,070 mg L⁻¹ Pb and 1,000 mg L⁻¹Cd for 16 days sand culture was evaluated. Results showed that the dry weights (DWs) of shoots and roots of I. pseudacorus were significantly decreased at 500 mg L⁻¹Pb and 25 mg L⁻¹Cd + 500 mg L⁻¹Pb treatments and the root DWs under all treatments were significantly decreased in comparison with that of control. The concentrations of Chla in the leaves were decreased at all treatments, while, the concentrations of Chlb and total carotenoids were not significantly decreased under 25 mg L⁻¹Cd and 25 mg L⁻¹Cd + 500 mg L⁻¹Pb treatments. The MDA and proline concentrations and POD activities in the shoots and roots were increased under treatments of 500 mg L⁻¹Pb and 25 mg L⁻¹Cd + 500 mg L⁻¹Pb, but POD activities in the shoots and roots and MDA concentrations in the shoots were significantly decreased at 25 mg L⁻¹ Cd treatment. The results of sub-cellular localization of Pb and Cd showed that numerous Pb deposits were found on the inner surface of died cell walls in the cortex treated with 2,070 mg L⁻¹ Pb and Cd deposits were found in the cell wall treated with 1,000 mg L⁻¹ Cd. Pb and Cd deposits were not found in the cytoplasm. The results indicated that POD and proline showed strong beneficial properties against Pb and Cd stress and there were some mechanisms keeping most cells with normal activities in the plant from Pb toxicity by sacrificing a few cells that accumulated a large amount Pb. Sub-cellular localizations of Pb and Cd in the root tip cells of I. pseudacorus were little difference with the localizations in other species of Iris in the previous studies.     

Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (<Emphasis Type="Italic">Scenedesmus obliquus</Emphasis>) and a consumer (<Emphasis Type="Italic">Daphnia magna</Emphasis>)

The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of colonies) in Scenedesmus at concentrations of 10–100 μl l⁻¹ that were far below the No Observed Effect Concentration (NOEC) value of 1,000 μl l⁻¹ for growth inhibition. The NOEC-value of FFD-6 for colony-induction was 3 μl l⁻¹. Daphnia survival was strongly affected by FFD-6, yielding LC_50–24h and LC_50–48h of 148 and 26 μl l⁻¹, respectively. In addition, clearance rates of Daphnia feeding on unicellular Scenedesmus were inhibited by FFD-6, yielding a 50% inhibition (EC_50–1.5h) at 5.2 μl l⁻¹ with a NOEC of 0.5 μl l⁻¹. When Daphnia were offered FFD-6-induced food in which eight-celled colonies (43 × 29 μm) were most abundant, clearance rates (~0.14 ml ind.⁻¹ h⁻¹) were only 25% the rates of animals that were offered non-induced unicellular (15 × 5 μm) Scenedesmus (~0.56 ml ind.⁻¹ h⁻¹). As FFD-6 concentrations in the treated food used in the experiments were far below the NOEC for clearance rate inhibition, it is concluded that the feeding rate depression was caused by the altered morphology of the Scenedesmus moving them out of the feeding window of the daphnids. The surfactant evoked a response in Scenedesmus that is similar to the natural chemically induced defensive reaction against grazers and could disrupt the natural information conveyance between these plankton organisms.     

Impact of nutrient components on production of the phytoestrogens daidzein and genistein by hairy roots of <Emphasis Type="Italic">Psoralea corylifolia</Emphasis>

Transformed hairy roots of Psoralea corylifolia were established by infection with Agrobacterium rhizogenes LBA 9402. The aim of this work was to elucidate the effects of media constituents on production of the phytoestrogenic isoflavones daidzein and genistein. A. rhizogenes strain LBA 9402 harboring Ri plasmid was used to transform stem segments of in vitro seedlings. The resultant hairy roots were confirmed by polymerase chain reaction (PCR) and exhibited Ri T-DNA. Transformed hairy root clones were cultured in Murashige and Skoog’s (MS) medium altered with different concentrations of NH₄ ⁺ and NO₃ ⁻ and their growth and production of isoflavones were assessed. Biomass and productivity increased when MS medium was supplemented with NH₄ ⁺ and NO₃ ⁻ at a ratio of 20:10. Increased yield of daidzein was obtained when sucrose level in the culture medium increased, whereas decreased level of sucrose favored genistein production. The hairy roots produced the highest levels of daidzein (2.06% dry wt.) and genistein (0.37% dry wt.) in the presence of low concentrations of PO₄ ³⁻. Hairy roots secreted trace amounts of daidzein and genistein into the culture medium. The present results demonstrated that the productivity of daidzein was 2.2-fold more than that of untransformed roots.