I. Alves-Pereira

Essential oils and hydrocarbons from leaves and calli of Origanum vulgare ssp. virens

Abstract The essential oil of leaves of O. vulgare spp. virens was composed of ca 50% monoterpenoids, 40% sesquiterpenenoids and 3% n -Alkanes. Linalool was the main constituent, representing more than 16% of the total essential oil. n -Alkanes were the major compounds found in hydrodistillates of calli induced from leaves. Green friable calli (G-calli) and dark abnormal root primordia containing calli (R-calli) of Origanum vulgare ssp. virens were induced from leaves and established in the presence of 0.25 mg and 1 mg 1 −1 (2,4-D), respectively. Leaves, of the same type of those used in the calli induction, G-calli and R-calli were submitted to hydrodistillation and the respective hydrodistillates were analysed by GC and GC-mass spectrometry. The hydrodistillate from leaves consisted of ca 50% monoterpenoids (35.2% oxygenated monoterpenes and 14.3% monoterpene hydrocarbons) and ca 40% of sesquiterpenoids (2.5% oxygenated sesquiterpenes and 37.4% sesquiterpene hydrocarbons). Linalool (16.4%) and ( E )- β -ocimene (6.6%) were the major oxygenated monoterpene and monoterpene hydrocarbon, respectively. Globulol (0.94%) and δ-elemene (12.85%) were the major oxygenated sesquiterpene and sesquiterpene hydrocarbon, respectively. n -Alkanes, namely pentacosane (0.97%), heptacosane (0.9%) and nonacosane (1.0%), were also present. Hydrodistillates from G- and R-calli did not contain either mono- or sesquiterpenoids; n -alkanes were the main compounds found. The alkane concentration in R-calli was more than twice that of G-calli. Naphthalene (0.5 μg g −1 dry wt) and eicosane, (0.9 μg g −1 dry wt) produced by R-calli were absent in G-calli. Squalene concentration in G-calli was 6.7 fold greater than that found in R-calli.

Can muscle fatty acid signature be used to distinguish diets during the marine trophic phase of sea lamprey (Petromyzon marinus, L.)?

Characterization of muscle and liver fatty acid profiles, determination of liver lipogenic and lipolytic activities and estimation of liver fatty elongases and desaturases activities of sea lamprey were realized at the beginning of the spawning migration. The muscle fatty acid profile was consistent with the location of capture, and revealed that animals captured far upstream from the river mouth presented the lowest C18:1ω9 levels and the highest relative proportions of C20:4ω6, C20:5ω3 (EPA), C22:5ω3 (DPA) and C22:6ω3 (DHA). These results suggest: (i) the vital importance of the conservation of C20:4ω6 as a precursor of eicosanoids; (ii) the retention of EPA, DPA and DHA for metabolic energy for reproduction; and (iii) the utilization of C18:1ω9 for metabolic fuel use in the beginning of the spawning period. Hepatic lipolysis and lipogenesis revealed significant differences which could, eventually, result from the diet during the parasitic phase of sea lamprey life cycle. Present results revealed that the muscle act as a fat depot site which explains the few significant correlations observed for fatty acids between muscle and liver. Muscle neutral lipids fatty acid signature at the beginning of the spawning migration can be used to distinguish differences in the diet of sea lampreys during the marine trophic phase of their life cycle.

CGDEase, a Pseudomonas fluorescens protein of the PLC/APase superfamily with CDP-ethanolamine and (dihexanoyl)glycerophosphoethanolamine hydrolase activity induced by osmoprotectants under phosphate-deficient conditions

A novel enzyme, induced by choline, ethanolamine, glycine betaine or dimethylglycine, was released at low temperature and phosphate from Pseudomonas fluorescens (CECT 7229) suspensions at low cell densities. It is a CDP‐ethanolamine pyrophosphatase/(dihexanoyl)glycerophosphoethanolamine phosphodiesterase (CGDEase) less active on choline derivatives, and inactive on long‐chain phospholipids, CDP‐glycerol and other NDP‐X compounds. The reaction pattern was typical of phospholipase C (PLC), as either phosphoethanolamine or phosphocholine was produced. Peptide‐mass analyses, gene cloning and expression provided a molecular identity for CGDEase. Bioinformatic studies assigned it to the PLC branch of the phospholipase C/acid phosphatase (PLC/APase) superfamily, revealed an irregular phylogenetic distribution of close CGDEase relatives, and suggested their genes are not in operons or conserved contexts. A theoretical CGDEase structure was supported by mutagenesis of two predicted active‐site residues, which yielded essentially inactive mutants. Biological relevance is supported by comparisons with CGDEase relatives, induction by osmoprotectants (not by osmotic stress itself) and repression by micromolar phosphate. The low bacterial density requirement was related to phosphate liberation from lysed bacteria in denser populations, rather than to a classical quorum‐sensing effect. The results fit better a CGDEase role in phosphate scavenging than in osmoprotection.

Plant growth, phytochemical accumulation and antioxidant activity of substrate-grown spinach

Spinach production in soilless cultivation systems, mainly in substrate, transplanted with soil blocks and drip-irrigation is increasing worldwide. However, spinach establishment with soil blocks, with several seedlings per block compared with traditional planting methods, may affect light interception by plant canopy, wetting and salt patterns in root medium and therefore the plant growth and functional value of spinach. The effects of soil block number (plant density) and emitters spacing on plant growth, nitrate, proline and total phenols content and antioxidant activity were evaluated in spinach (Spinacia oleracea L). Five seedlings per soil block were transplanted to Styrofoam boxes filled with the substrate and grown during winter in an unheated greenhouse. Four treatments were carried out with two soil block numbers [8 (160 plants/m2) and 14 (280 plants/m2) soil blocks per Styrofoam box] and two emitter spacing [emitters spaced every 25 and 12.5 cm, respectively, with 4 and 8 emitters per Styrofoam box]. Neither plant density nor emitter spacing had any effect on shoot dry weight. Fresh yield increased as planting density and the number of emitters per Styrofoam box increased. The yield in Styrofoam boxes with 160 plants/m2 and 8 emitters (3.85 kg m−2) was ≈31 % lower than that obtained in treatment with 280 plants/m2 and 8 emitters (5.09 kg m−2). However, the leaf blade of the latter treatment presented a higher content of phenols and proline and greater antioxidant activity (FRAP and DPPH) as well as lower content of nitrate and lesser PDH activity. Decrease of space between emitters reduced the leaf blade nitrate concentration of spinach grown in a greenhouse during the winter. Leaf blade antioxidant activity (FRAP) decreased as planting density increased.

Effects of atrazine, isoproturon and diuron on glutathione metabolism of Saccharomyces cerevisiae

Abstract Triazines and phenylureas, mainly used in agricultural applications for the selective control of germinating grasses and broad-leaved weeds, are often found in contaminated groundwater, surface water and the effluents of wastewater treatment plants. The toxicity of these herbicides in eukaryotic cells is poorly understood. Saccharomyces cerevisiae is a promising unicellular organism for the toxicological evaluation of xenobiotics because its metabolism is similar to that of higher-level organisms. Consequently, the aim of this study was to compare the effects of three herbicides on yeast-cell growth and the glutathione cycle. Saccharomyces cerevisiae grown in the presence of 5 or 50 μm atrazine, diuron or isoproturon were compared with control cells grown in a rich medium. The results show that the glutathione-dependent buffer capacity decreased significantly in S. cerevisiae grown in the presence of both levels of any of the three herbicides, except in cells exposed to 50 μm isoproturon. In addition, chlorine herbicides inhibited cell growth, probably due to a decrease in antioxidant power and glutathione reductase activity. Isoproturon at 50 μm induced yeast-cell growth, increasing the buffer capacity mediated by glutathione as well as glutathione reductase and glutathione peroxidase activities of UE-ME3 strain. This strain may be useful in studies of isoproturon degradation.

Can mitochondrial malondialdehyde content be a useful tool to evaluate sea lamprey juveniles’ capacity to seawater acclimatization?

Abstract The sea lamprey is an anadromous species that migrates twice during its life cycle between freshwater and seawater. Microphagous larvae generally spend 4–5 years burrowed in the substrate of rivers and streams before undergoing metamorphosis that ends with the beginning of the juvenile trophic migration. Once metamorphosis is complete, sea lamprey juvenile downstream migrants are fully tolerant to seawater salinity. Pollution resulting from industrial effluents may disturb the seawater acclimatization causing oxidative damage, and ultimately may lead to a decrease of sea lamprey population. The aim of this study was to compare salt acclimation of sea lamprey juveniles captured in river basins with different levels of aquatic pollution, using mitochondrial glutathione (GSH) and malondialdehyde (MDA) of gills and liver as markers of physiological stress and cell damage. The results showed that juveniles from the Lima basin exhibited the highest levels of mitochondrial MDA in gills, even though significant changes in the stress markers of mitochondrial gills of all animals subject to salt acclimation were not detected. In addition, an increase in the oxidative damage of hepatic mitochondria of macrophthalmia from the Vouga basin suggests the occurrence of metabolic failures with the potential to disturb the capacity to adaptation to the marine environment.

Heat shock and titanium dioxide nanoparticles decrease superoxide dismutase and glutathione enzymes activities in Saccharomyces cerevisiae

Abstract The exposure of living organisms to metals can generate reactive oxygen species and failure in their antioxidant defences, triggering oxidative stress and oxidative damage. Despite the intensive use of engineered nanoparticles in numerous consumer and industrial products, data on their potential hazards in eukaryotic cells and their dependence on environmental factors such as temperature are still scarce. The aim of this study was to evaluate the antioxidant response of Saccharomyces cerevisiae, grown in presence of glycerol and glucose, to 5 μg/ml titanium dioxide nanoparticles (size<100 nm) under heat shock conditions. The results showed that biomass, levels of reactive oxygen species and glutathione reductase activity in respiratory/fermentative cells were higher than those detected in respiratory cells. Furthermore, respiratory/fermentative cells exhibited lower levels of glutathione, malondialdehyde, cytoplasmic catalase and glutathione peroxidase than those detected in the respiratory yeast. Saccharomyces cerevisiae grown in the presence of glycerol, glucose and titanium dioxide nanoparticles, under heat shock conditions, caused oxidative stress, due to a decrease in antioxidant defences such as superoxide dismutases or a slowdown of the glutathione cycle, relative to cells grown in presence of glycerol and glucose.