Physiological effects of mercury in the lichens Cladonia arbuscula subsp. mitis (Sandst.) Ruoss and Peltigera rufescens (Weiss) Humb

This study aimed at investigating the cellular distribution of Hg in the lichens Cladonia arbuscula subsp. mitis and Peltigera rufescens treated with Hg²⁺ and at testing if Hg treatment affects selected physiological parameters. In both species, increasing Hg accumulation under increasing Hg supply in the treatment solutions was found. P. rufescens showed a higher intracellular accumulation. Photosynthetic parameters were negatively affected in both species, as indicated by the decrease in photosynthetic pigments content, photosynthetic efficiency and chlorophyll integrity. Cell membranes of both species endured damage as indicated by the increase in the concentration of products of lipid peroxidation and decrease in ergosterol content. Nevertheless, differences between the two species were found, suggesting a differential sensitivity to Hg.     

Occurrence of emerging organic contaminants in a tropical urban catchment in Singapore

The aim of this study was to test in a short term laboratory experiment the accumulation and physiological effects of As in the epiphytic lichen Xanthoria parietina. Arsenic content in treated samples increased progressively with increasing concentration in treatment solutions. Treatment of X. parietina thalli with 0.1, 1, 10 ppm As solutions caused significant decrease of viability, measured as intensity of respiratory activity, and damages to cell membranes, assessed by increase of electric conductivity of rinsing water and lipid peroxidation products. Soluble proteins content decreased and H₂O₂ content increased already at the lowest As concentration tested (0.01 ppm). Photosynthetic efficiency, measured in terms of F_V/F_M ratio, decreased significantly only at the highest As concentration (10 ppm). It was concluded that As exposure causes physiological stress both on the mycobiont and the photobiont and that cell membrane damage, expressed in terms of electric conductivity of rinsing water, is the parameter most affected by As treatment.     

Inefficiencies analysis of a point-focus CPV∕T system

In this paper, a point-focus concentrating photovoltaic and thermal (CPV∕T) system, sized for a domestic application, is presented in order to evaluate its inefficiencies and the related costs. The CPV∕T system adopts parabolic concentrator mirrors to reflect the light on triple-junction cells InGaP∕InGaAs∕Ge (indium--gallium phosphide∕indium--gallium arsenide∕germanium) placed on pipes, where the cooling fluid flows; CPV∕T system consists of three modules in parallel linked to a tank that works as hot water storage. The main maintenance problems are due to: moving parts such as the tracking system, cell wear linked to hotspot problems and optics cleaning. In particular, the model presented allows us to evaluate electric and thermal outputs, energy inefficiencies, and maintenance costs of the CPV∕T system. The analysis has been subdivided in several steps and a FMECA (Failure Mode, Effects and Criticality Analysis) approach has been considered to investigate the main failure modes and their relative effects in terms of efficiency losses and intervention costs. So, the inefficiencies analysis has allowed to identify the system malfunction causes, evaluating the impact due to the stops for each type of fault. Hence, an economic analysis has allowed to evaluate the CPV∕T system convenience when inefficiencies and maintenance incidence are also considered.     

Cell size dependence of additive versus synergetic effects of UV radiation and PAHs on oceanic phytoplankton

Polycyclic Aromatic Hydrocarbons’ (PAHs) toxicity is enhanced by the presence of ultraviolet radiation (UVR), which levels have arisen due to the thinning of the ozone layer. In this study, PAHs’ phototoxicity for natural marine phytoplankton was tested. Different concentrations of a mixture of 16 PAHs were added to natural phytoplankton communities from the Mediterranean Sea, Atlantic, Arctic and Southern Oceans and exposed to natural sunlight received in situ, including treatments where the UVR bands were removed. PAHs’ toxicity was observed for all the phytoplankton groups studied in all the waters and treatments tested, but only for the pico-sized group a synergetic effect of the mixture and UVR was observed (p = 0.009). When comparing phototoxicity in phytoplankton from oligotrophic and eutrophic waters, synergy was only observed at the oligotrophic communities (p = 0.02) where pico-sized phytoplankton dominated. The degree of sensitivity was related to the trophic degree, decreasing as Chlorophyll a concentration increased.     

固定化细菌吸附铅和镉最佳包埋条件的确定

以聚乙烯醇和海藻酸钠为包埋剂,对细菌进行包埋固定化,以吸附铅、镉能力为主要考察指标,同时从机械强度、传质性、耐酸性等方面综合考虑,选择最优化的固定化小球最佳配方。并按照最佳配方进行了验证实验,对铅的吸附量达到0.9820mg/g,对镉的吸附量达到0.4670mg/g,机械强度、传质性和耐酸性都较好。     

Research Articles

The metabolism of phenanthrene was studied both in cell suspension cultures of wheat (Triticum aestivum) and soybean (Glycine max), and in intact plants of the water mossFontinalis antipyretica. Metabolism in cell suspension cultures strongly differed between the monocotyle and the dicotyle plant. Only small amounts oftrans-phenanthrene-9,10-dihydrodiole and phenanthrene-9,10-dione were detectable in the wheat culture. Soybean cultures, in contrast demonstrated a strong turnover resulting in a 75% reduction of the initial phenanthrene concentration. Metabolites were phenanthrene-9,10-dione, not further characterized polar metabolites and bound residues. Intact plants ofFontinalis antipyretica metabolized only small amounts of phenanthrene. Data obtained from cell cultures did not provide information for the metabolic potential in intact plants. Therefore standardized tests with model systems like suspension cultures lead to inadequate assessment of the ecological risk of certain xenobiotics.     

A study of chromosomal aberrations in amniotic fluid cell cultures

This paper represents the analysis of 1916 routine amniotic fluid specimens harvested by an in situ fixation technique in a prospective study with regard to cultural chromosome anomalies. Excluding constitutional abnormalities, 2·9 per cent of 19432 cells analysed showed some form of chromosome anomaly, terminal deletions (57 percent) and chromatid/chromosome breaks and gaps (18 per cent) being the most frequent, followed by interchange aberrations (13 per cent) and trisomy (5 per cent). No case was found of more than one colony from the same culture showing the same anomaly without it being present in other cultures from the same fluid. The wholly abnormal colonies had a surplus of trisomies and from the mathematical considerations presented one may infer that these are likely to reflect the presence of abnormal cells in the amniotic fluid. Partly abnormal colonies appeared at a frequency that would correspond to virtual absence of selection against chromosomally abnormal cells when cultured in vitro. The aberrations found were similar to those seen as single cell anomalies, except for chromatid breaks and exchanges. The data suggest a basic preferential induction of trisomy for chromosomes 2,18,21, and the Y-chromosome. Structural aberrations showed a marked clustering of breakpoints around the centromeres. The frequency of mutant cells was low (1·4 × 10⁻³) before culture was initiated. At harvest, the frequency of abnormal cells was much higher (3 × 10⁻²) corresponding to 3 × 10⁻³ mutations per cell per generation accumulating over approximately ten generations in vitro.     

A selective N,N-dithenoyl-rhodamine based fluorescent probe for Fe3+ detection in aqueous and living cells

A novel N,N-dithenoyl-rhodamine based fluorescent and colorimetric Fe3+probe 1 was designed and synthesized by only one step from Rhodamine B hydrazide and 2-thiophenecarbonyl chloride.The structure of probe 1 was characterized by ~1 H NMR/~(13)C NMR spectroscopy,IR spectroscopy,and HRMS spectrometry.Accompanying with significant changes in visual color and fluorescent spectrum,probe 1 displayed good sensitivity for Fe~(3+)with an abroad pH span.The detection limit(3.76 μmol/L,0.2 mg/L) for Fe~(3+)was lower than WHO recommended value(0.3 mg/L) for drinking water.Using two thiophene carbonyl groups as coordinating functional recognition group,probe 1 showed excellent selectivity towards Fe3+over diverse coexistent metal ions and anions.The sensing mechanism between dithenoyl-substituted probe 1 and Fe~(3+)was further confirmed by ~1 H NMR and IR titration experiments,binding constants study,and Job's plot analysis.Furthermore,probe 1 also exhibited good cell membrane permeability and could be used as an efficient Fe~(3+) probe in living human cells.     

Distribution of14C-TNT and derivatives in different biochemical compartments ofPhaseolus vulgaris

¹⁴C-TNT was used to quantify the uptake rate and metabolic turnover of TNT inPhaseolus vulgaris. Seventeen plants were analysed by a special cell fractionation method with polar and nonpolar solvents and enzymes. We obtained three cytoplasmic fractions and five cell wall derived fractions. The recovery rate was 72% as measured by liquid scintillation counting.¹⁴C partitioned almost in equal amounts with approximately 50% in the cytoplasm and in the cell wall. The majority of the TNT-metabolites are present in the cytoplasm as was shown by GC/ ECD and thin layer chromatography. The¹⁴C in the cell wall is bound probably resulting in long-term immobilisation of these metabolites. We conclude that plants may also be a model for nitroaromatic turnover and immobilisation in soil components.     

Effect of iron and dissolved silica on primmorphs of Petrosia ficiformis (Poiret, 1789)

The suitability of the primmorphs system as a good model for biotechnological applications led researchers on primmorphs to look for a medium to stimulate cell proliferation and therefore growth of aggregates. Recent efforts have focused on the use of Fe⁺³ and Si that, supplemented to cell culture medium, were found to be promising for growth and morphogenesis of the sponge Suberites domuncula. In this work, we analysed the effect of iron and dissolved silica on primmorphs of Petrosia ficiformis, by testing them at different concentrations in successive experiments. The purpose of these experiments was to test their effect on primmorphs and individuate their optimal concentration for this species. Our results suggest a negative effect of iron on primmorphs of P. ficiformis and a positive effect of silica on primmorphs size and spiculogenesis at a concentration of 120 μM.