Mercury antagonists: loss of phototactic response in the brine shrimp artemia and its prevention by thiamine

The positive phototactic behavior ofArtemia was disturbed when larvae cultured in 0.25 M NaCl were introduced into 10^?7 to 10^?5 M HgCl₂. At 10^?8 M, and in controls, Hg had no effect either on orientation or mortality, and 65% of the larvae were collected at the light source in 30 min or less. In contrast, at 10^?6 M, only 29% were able to do so. The presence of 10^?4 M thiamine hydrochloride in the excystment medium prevented fully the loss of light-sensitivity.     

Mercury antagonists: Effects of sodium chloride and sulfur group (VIa) compounds on excystment of the brine shrimp artemia

Brine shrimp excystment, although highly resistant, is severely inhibited by mmolar mercuric chloride. The presence of 100 mmolar NaCl largely prevents the toxic response. The chloride effect can be explained if the toxic Hg species, neutral HgCl₂, is converted into HgCl _inf3 ^sup2? and HgCl _inf4 ^sup2? since charged species not likely to penetrate cyst walls. Other Hg antagonists include SO _in3 ^su2? , SeO _inf3 ^sup2? , TeO _inf3 ^sup2? and TeO _inf4 ^sup2? , but not SO _inf4 ^sup2? and SeO _inf4 ^sup2? . The activity of both Te species can be explained by ready reduction of Te(VI) to Te(IV). Significant anti-mercurial effects were seen in mmolar thiols, ethionine and organoselenium compounds. Thiamine and methionine were both active Hg antagonists at 10 to 30 mmolar levels. The activities of S, Se and Cl^? compounds show that both geochemical and physiological modes of defense against and adaptation to high Hg levels exist.     

Uptake,assimilation and transport of nitrogen compounds by plants

This paper reviews current knowledge and presents some new information on the metabolism of nitrogen in various species of higher plants.The role of the root system is considered. It is shown that the roots of many herbaceous and woody plants can manufacture organic compounds of nitrogen from the nitrate or other forms of inorganic nitrogen they absorb from the medium. The extent to which they do this varies greatly with the age and nutrition of the plant and with the environmental conditions under which it is growing. The relationship is examined between the synthetic activities of the root and its activity in upward transport of nitrogen to the shoot. The latter process takes place predominantly, if not exclusively, in the xylem, and in each species one or more nitrogen-rich compounds, e.g., amides, ureides and amino acids, carry the bulk of the nitrogen leaving the root. A second group of plants is described in which roots do not function to any extent in the reduction of nitrate.Consideration is given to the fate of recently absorbed nitrogen once it reaches the shoot system. An inorganic source such as nitrate, or molecules such as amides containing surplus amino groupings, are shown to serve as nitrogen sources for synthesis of amino acids required for protein synthesis. Some of these amino acids arise directly from the photosynthetic apparatus. Alternatively, surplus nitrogen arriving from the root may be stored in the shoot, from where it is drawn upon extensively if uptake by the root fails to keep pace with the shoot's demands for nitrogen.The transport system for nitrogen is examined for the whole plant. The classes of sources and sinks for nitrogen are described, and information presented on the types of nitrogenous solutes they receive from the xylem and phloem.     

Inhibition of citrus postharvest pathogens by vapor of citral and related compounds in culture

The vapors of citral, its isomers geranial and neral, and its related compounds were examined for their effect on Penicillium digitatum, Penicillium italicum, and Geotrichum candidum, the major fungi responsible for postharvest spoilage of citrus. Vapor of citral and its two isomers generated from 15 microL L(-1) aqueous solutions in Petri dishes inhibited development of the three pathogens, with concentrations of 2-6 microL L(-1) also being effective against P. italicum. Vapors of citral and geranial from 15 microL L(-1) solutions were fungicidal to P. digitatum and G. candidum, while neral was fungicidal to G. candidum. Citral-related compounds were much less effective, with effectiveness decreasing from citronellal to citronellol and citronellic acid. R and S isomers of these three citral-related compounds generally had similar effects on the fungi tested.     

Stimulation of growth in papaya and other plants by dilute salt solutions

The growth of Solo papaya, Winter rye and Chinese cabbage is enhanced when they are cultivated in saline waters at 2500 to 3200 ppm total dissolved solids. Stimulation began at the germinating stage with rye and cabbage, but in the case of papaya only with 6 to 8 week old plants. The stimulation noted was not nutritionally based, as a complete nutrient was included.     

Boron absorption by crop plants as affected by other nutrients of the medium

Numerous reports on boron nutrition of plants have been published since WARINGTON (15), using Vicia faba, first discovered in 1923 that boron is essential for the growth of higher plants. Inorganic (7, 9, 11) and organic (1) constituents of the growth medium and climatic conditions such as light intensity (13), photoperiod (5, 16), and drying and wetting of the soil (10) are some of the factors affecting boron uptake by plants.     

Mercury from power plants: A probabilistic approach to the evaluation of potential health risks

Estimating the impacts of mercury (Hg) power plant emissions on the environment and human health involves the prediction of chemical concentrations in the different environmental media and the foodchain. As calculations show the ingestion pathway to dominate Hg risk, the reliable characterization of the processes influencing Hg concentrations in environmental media other than air is of particular importance. In this context, we present and implement an approach for the evaluation of Hg multimedia risks associated with power plant emissions. The approach is based on the investigation of four critical components influencing Hg ingestion risk: (1) Hg deposition; (2) hydrologic environment; (3) Hg uptake by fish; and (4) Hg uptake by vegetation. To capture the variability in the conditions affecting Hg risk, the problem is handled in a probabilistic way, where the influential parameters are assigned probability distributions or possible value ranges that cover a wide spectrum of emission possibilities and environmental conditions. Particular emphasis is given to the aquatic environment.     

Permeability profile estimation of flavonoids and other phenolic compounds by biopartitioning micellar capillary chromatography

This paper points out the usefulness of biopartitioning micellar chromatography (BMC) using capillary columns as a high-throughput primary screening tool providing key information about the oral absorption, skin permeability, and brain-blood distribution coefficients of 15 polyphenols (6 flavones, 2 flavonols, a flavanone, 2 flavan-3-ols, 3 phenolic acids, and a phloroglucinol) in a simple and economical way. For the compounds studied, except vicenin-2, rutin, chlorogenic acid, p-hydroxycinnamic acid, and 4-hydroxybenzoic acid, maximal oral absorption (>90%) can be expected, if there are not solubility problems or metabolic processes. On the other hand, the most retained compounds in BMC, that is, 5-hydroxyflavone, flavone, and flavanone, show the highest brain-blood distribution coefficients and skin permeability coefficients.     

Analysis of phenolic and other aromatic compounds in honeys by solid-phase microextraction followed by gas chromatography-mass spectrometry

The solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was used for the analysis of phenolic and other aromatic compounds in honey samples from different floral origin. Different parameters affecting the efficiency of the extraction, such as the type of the stationary phase of the fiber, NaCl and acetic acid addition, and extraction time, were optimized for the detection of the maximum number of compounds in the shortest analysis time. A total of 31 compounds were detected, with most of them identified and quantified by GC-MS. The principal component analysis (PCA) was applied to the data matrix; the results allowed for the differentiation between honeydew and nectar honeys on the basis of the salicylic acid concentration. It was found that this acid has a high contribution in the honeydew group (71.2-705.9 microg/100 g of honey) compared to the nectar honey group (0-47.6 microg/100 g of honey). The comparison of data in each honey group enabled us to characterize the floral source of some honeys using some aromatic compounds as markers.     

Fast and simple liquid chromatographic determination of nonphosphorylated thiamine in infant formula, milk, and other foods

A very fast and simple method for determination of nonphosphorylated thiamine in infant formula products, milk, and other nonfortified foods using reverse-phase ion-pairing liquid chromatography (LC) has been developed. Sample preparation consists of merely acid treatment to precipitate protein, followed by gravity filtration. No concentration, extraction, derivatization, or preliminary column cleanup is necessary. The chromatography is done on muBondapack C18 with an aqueous mobile phase containing 0.15% sodium hexane sulfonate, 20% MeOH, 1.5% HOAc, and 0.1% EDTA at a flow rate of 2.5 mL/min. Ultraviolet detection at 248 nm is used. A typical run takes 7 min, and 60 samples can be processed in 4 h. Results average from 96 to 104% of theory for the infant formula products analyzed. A 99 to 103% recovery of spike has been demonstrated. Method precision is good (2 to 4% RSD, short-term, and 2 to 5% RSD, long-term, depending on sample type). Peak separation from thiamine phosphate esters is achieved. Specificity is demonstrated by UV spectral scan and absorbance ratios. Equivalency to a microbial method (validated against the official AOAC fluorometric method) was established. The method is used for high-volume quality control testing of milk-based infant formula products in the ready-to-use, concentrate, or powder form.     

In-depth mechanistic study on the formation of acrylamide and other vinylogous compounds by the maillard reaction

The formation of acrylamide was studied in low-moisture Maillard model systems (180 degrees C, 5 min) based on asparagine, reducing sugars, Maillard intermediates, and sugar degradation products. We show evidence that certain glycoconjugates play a major role in acrylamide formation. The N-glycosyl of asparagine generated about 2.4 mmol/mol acrylamide, compared to 0.1-0.2 mmol/mol obtained with alpha-dicarbonyls and the Amadori compound of asparagine. 3-Hydroxypropanamide, the Strecker alcohol of asparagine, generated only low amounts of acrylamide ( approximately 0.23 mmol/mol), while hydroxyacetone increased the acrylamide yields to more than 4 mmol/mol, indicating that alpha-hydroxy carbonyls are much more efficient than alpha-dicarbonyls in converting asparagine into acrylamide. The experimental results are consistent with the reaction mechanism based on (i) a Strecker type degradation of the Schiff base leading to azomethine ylides, followed by (ii) a beta-elimination reaction of the decarboxylated Amadori compound to afford acrylamide. The beta-position on both sides of the nitrogen atom is crucial. Rearrangement of the azomethine ylide to the decarboxylated Amadori compound is the key step, which is favored if the carbonyl moiety contains a hydroxyl group in beta-position to the nitrogen atom. The beta-elimination step in the amino acid moiety was demonstrated by reacting under low moisture conditions decarboxylated model Amadori compounds obtained by synthesis. The corresponding vinylogous compounds were only generated if a beta-proton was available, for example, styrene from the decarboxylated Amadori compound of phenylalanine. Therefore, it is suggested that this thermal pathway may be common to other amino acids, resulting under certain conditions in their respective vinylogous reaction products.     

Source and selectivity in the accumulation of mercury and other metals by the plants of Mt. Etna

The air Hg content at and near the summit of Mt. Etna is approximately 500- to 2000-fold lower than it is in the atmospheres around Antarctic, Hawaiian and Icelandic volcanoes. In contrast, the soils and plants on Mt. Etna show only 10- to 30-fold reductions in Hg content; in other words, there is at least a ten-fold enrichment relative to air. This disparity called into question the source of Hg in the vegetation and upper soil layers. Soils and a variety of plant species were analyzed for Hg, Fe, Cu, and Mn content at a number of stations on Mt. Etna including several also sampled for air Hg, and compared with the data for plants and soils from other volcanic and non-volcanic locations, especially Hawaii, Africa and Iceland. Etna vascular plants do not accumulate Hg, and lichens do so only to a moderate extent. Relative to their Fe content, however, all the Etna soils are enriched in Hg, but the reverse is true for Cu relative to Hg. The plants, on the other hand, when compared with their soils, are enriched in Hg relative to Cu. By comparing Fe/Hg atomic ratios for plants and soil, we calculated an Enrichment Factor (EF) for Hg. This value ranged from 19 to 102 for Etna, and 19 to 184 for all subtropical plants discussed here. The Hg EF for Icelandic samples was ca. 823, reflecting other environmental/geochemical determinants. No net surface deposition of Hg takes place on Etna from plant or atmospheric sources, and the relative Hg contents of soils and plants do not show a consistent relation to air Hg concenctration. Nevertheless, the plant/soil Cu and Hg ratios (CR) vary similarly as do the atomic ratio (AR) values for Fe and Hg. We conclude from these relationships that the atmosphere is not a major source of plant (or soil) Hg and that the likely alternatives are: release at some relatively remote point in time, but not to any significant degree since; release into the atmosphere as Hg = species other than Hg⁰; or movement from very deep subsurface compartments. These alternatives are not mutually exclusive. It is highly improbable that summit emissions constitute a significant source of Hg in the Mediterrean Basin.     

Nature conservation in Italy: Proposed national and regional parks and other areas deserving protection

The complex geological history of Italy is responsible for the remarkable number of different landscapes and ecosystems present today. The immigration of animals and plants from neighbouring lands, when natural bridges were available, the survival of warm species along the coast during the Quaternary glaciations, and the relict populations which remained in the Apennines after the withdrawal of the ice, have all contributed to the richness of wildlife. In order to preserve adequately this biotic variety it is necessary to protect a large number of separate areas as National or Regional Parks or as nature reserves. In addition, the existence of important bird migration routes along or across the Italian peninsula and islands makes it necessary to provide safe areas where these birds can rest and feed. In spite of these needs, the State and the Regional Governments are not sufficiently concerned with wildlife and environmental conservation and so far have done very little to improve the protection of nature in Italy. In this paper 56 main areas are discussed which are in urgent need of protection from commercial speculation and the threat of irreparable damage. The authors hope that national and international public opinion will encourage the Italian Government to establish many more protected territories and to provide the resources for realistic management.     

Growth promotion and protection against salt stress by Pseudomonas putida Rs-198 on cotton

The strain Rs-198 isolated from alkaline soil was investigated and identified as Pseudomonas putida on the basis of its physiological and biochemical properties as well as its 16S rDNA sequence analysis. The effects of the strain Rs-198 on cotton seedling growth under salt stress were studied. The results indicated that Rs-198 could protect against salt stress and promote cotton seedling growth. After treatment with Rs-198, the germination rate and healthy stand of cotton were increased by 23.8% and 30.7%, respectively. Individual plant height, fresh weight and dry weight of cotton seedling were increased by 12.8%, 30.7% and 10.0%, respectively as compared to the control (CK). In the fields, Rs-198 also exhibited the ability to increase the cotton's germination rate and healthy stand, which were 16.0% and 22.4% higher than that of CK. Further analysis showed that Rs-198 could increase the absorption of the Mg²⁺, K⁺ and Ca²⁺ and decrease the uptake of the Na⁺ from the soil and also improve the production of endogenous indole acetic acid (IAA) content and reduce the abscisic acid (ABA) content of cotton seedling under salt stress.     

Simultaneous determination of thiamine and riboflavin in foods by liquid chromatography

Recent methods for determination of thiamine (thiochrome) and riboflavin by liquid chromatography (LC) are outlined and discussed, and a new method allowing the simultaneous determination of these 2 vitamins by using a single fluorescence detector is described. This system involves an ODS 5 micron ultrasphere column and a pH 7.5 mobile phase composed of 0.005M tetrabutyl ammonium phosphate in methanol-water (20 + 80).     

Antioxidant and anti-inflammatory activities of selected medicinal plants containing phenolic and flavonoid compounds

The antioxidant, anti-inflammatory, and cytotoxic activities of water and ethanol extracts of 14 Chinese medicinal plants were investigated and also their total phenolics and flavonoid contents measured. The antioxidant activity was evaluated in a biological assay using Saccharomyces cerevisiae , whereas the radical scavenging activity was measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Total phenolics and flavonoid contents were estimated by Folin-Ciocalteu and aluminum chloride methods, respectively. The anti-inflammatory activities of the plant extracts were determined by measuring the inhibition of production of nitric oxide (NO) and TNF-α in LPS and IFN-γ activated RAW 264.7 macrophages. Their cytotoxic activities against macrophages were determined by Alamar Blue assay. Four plants, namely, Scutellaria baicalensis , Taxillus chinensis , Rheum officinale , and Sophora japonica , showed significant antioxidant activity in both yeast model and also free radical scavenging methods. The ethanol extract of S. japonica showed highest levels of phenolics and flavonoids (91.33 GAE mg/g and 151.86 QE mg/g, respectively). A positive linear correlation between antioxidant activity and the total phenolics and flavonoid contents indicates that these compounds are likely to be the main antioxidants contributing to the observed activities. Five plant extracts (S. baicalensis, T. chinensis, S. japonica, Mahonia fortunei , and Sophora flavescens ) exhibited significant anti-inflammatory activity by in vitro inhibition of the production of NO and TNF-α with low IC(50) values. These findings suggest that some of the medicinal herbs studied in this paper are good sources of antioxidants.     

Effects of Fe compounds on nutrient uptake by plants grown in sand media with different pH

The effect of soil and foliar application of different iron (Fe) compounds (FeSO₄, Fe‐EDTA, Fe‐EDDS, and Fe‐EDDHA) on nutrient concentrations in lettuce (Lactuca sativa cv. Australian gelber) and ryegrass (Lolium perenne cv. Prego) was investigated in a greenhouse pot experiment using quartz sand as growth medium. Soil application was performed in both the acidic and alkaline pH range, and foliar application to plants grown in the alkaline sand only. Lettuce growth was depressed by Fe deficiency in the alkaline sand, whereas the treatments had no effect on ryegrass growth. Soil‐applied Fe compounds raised the Fe concentrations in lettuce. This was especially true for the Fe chelates, which also increased yields. Soil‐applied Fe compounds had no statistically significant effect on Fe concentrations in ryegrass. Concentrations of manganese (Mn) in lettuce were equally decreased by all soil‐applied chelates. In the alkaline sand, soil application of Fe‐EDDHA elevated copper (Cu) and depressed zinc (Zn) concentrations in lettuce. The chelates increased Zn concentration in ryegrass. Foliar application of Fe‐EDDS increased Fe concentrations in lettuce and in ryegrass most. Fe‐EDDHA depressed Mn and Zn concentrations in lettuce more than other Fe compounds, suggesting the existence of another mechanism, in addition to Fe, that transmits a corresponding signal from shoot to roots with an impact on uptake of micronutrients.