Characterization of the temporal induction of hepatic xenobiotic-metabolizing enzymes by glucosinolates and isothiocyanates: requirement for at least a 6 h exposure to elicit complete induction profile

A mechanism of action of chemopreventive glucosinolates/isothiocyanates, established largely in vitro, is to modulate carcinogen-metabolizing enzymes. Extrapolation in vivo involves relating in vitro concentrations to plasma/tissue concentrations attained in vivo, thus assuming that even transient exposure modulates enzyme activity. To test this hypothesis, precision-cut rat liver slices were incubated with glucosinolates for up to 24 h, and the O-dealkylation of methoxyresorufin and ethoxyresorufin was determined; increased activities were observed only at incubations of at least 6 h. To evaluate phase II enzymes, isothiocyanates, namely, sulforaphane, erucin, and phenethyl isothiocyanate, were similarly incubated; quinone reductase increased after incubation for 6 h or longer. When glutathione S-transferase was monitored, the phenethyl isothiocyanate-manifested rise necessitated at least a 6 h incubation, whereas in the case of sulforaphane and erucin, the activity was elevated after only 2 h. It is inferred that a rise in carcinogen-metabolizing enzymes by glucosinolates/isothiocyanates necessitates tissue exposure of at least 6 h.     

Phase transitions, solubility, and crystallization kinetics of phytosterols and phytosterol-oil blends

The thermal properties, solubility characteristics, and crystallization kinetics of four commercial phytosterol preparations (soy and wood sterols and stanols) and their blends with corn oil were examined. Differential scanning calorimetry (DSC) revealed narrow melting peaks between 138 and 145 degrees C for all phytosterol samples, reversible on rescan. Broader and less symmetrical melting transitions at lower temperatures with increasing oil content were observed for two samples of phytosterol-oil admixtures. The estimated, from the solubility law, deltaH values (34.7 and 70.7 mJ/mg for wood sterols and stanols, respectively), were similar to the DSC experimental data. Fatty acid esters of soy stanols differing in the chain length of the acyl groups (C2-C12) exhibited suppression of the melting point and increase of the fusion enthalpy with increasing chain length of the acyl group; the propionate ester exhibited the highest melting point (Tm: 151 degrees C) among all stanol-fatty acid esters. Solubility of phytosterols in corn oil was low (2-3% w/w at 25 degrees C) and increased slightly with a temperature rise. Plant sterols appeared more soluble than stanols with higher critical concentrations at saturation. The induction time for recrystallization of sterol-oil liquid blends, as determined by spectrophotometry, depended on the supersaturation ratio. The calculated interfacial free energies between crystalline sediments and oil were smaller for sterol samples (3.80 and 3.85 mJ/m2) than stanol mixtures (5.95 and 6.07 mJ/m2), in accord with the higher solubility of the sterol crystals in corn oil. The XRD patterns and light microscopy revealed some differences in the characteristics among the native and recrystallized in oil phytosterol preparations.     

Boron remobilization at low boron supply in olive (Olea europaea) in relation to leaf and phloem mannitol concentrations

For plant species in which a considerable portion of the photoassimilates are translocated in the phloem as sugar alcohols, boron is freely translocated from mature organs to growing tissues. However, the effects of decreased plant boron status on boron remobilization are poorly understood. We conducted a growth chamber experiment (CE) and a field experiment (FE) to study the effects of low boron supply on boron remobilization in olive (Olea europaea L.), a species that transports considerable amounts of mannitol in the phloem. For the CE, several physiological parameters were compared between control (B+) and boron-deficient olive plants (B-) during the expansion of new leaves. Boron remobilization was assessed by measuring boron content of selected leaves at the beginning and at the end of the CE. As expected, boron was remobilized from mature leaves to young leaves of B+ plants; however, considerable boron remobilization was also observed in B- plants, suggesting a mechanism whereby olive can sustain a minimum boron supply for growth of new tissues despite an insufficient external boron supply. Boron deficiency caused inhibition of new growth but had no effect on photosynthetic capacity per unit leaf surface area of young and mature leaves, thereby altering the carbon utilization pattern and resulting in carbon allocation to structures within the source leaves and accumulation of soluble carbohydrates. Specifically, in mature B- leaves in the CE and in B- leaves in the FE, mannitol concentration on a leaf water content basis increased by 48 and 27% respectively, compared with controls. Carbon export ability (assessed by both phloem anatomy and phloem exudate composition of FE leaves) was enhanced at low boron supply. We conclude that, at low boron supply, increased mannitol concentrations maintain boron remobilization from source leaves to boron-demanding sink leaves.     

Persistence and efficacy of spinosad on wheat,maize and barley grains against four major stored product pests

The insecticidal and residual effect of spinosad on wheat, maize and barley grain was evaluated in the laboratory against adults of Sitophilus oryzae (F.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), Tribolium confusum (DuVal) (Coleoptera: Tenebrionidae), Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) as well as against larvae of T. confusum. Spinosad was applied as a solution to 2 kg lots of each commodity at three concentrations, 0.1, 0.5 and 1 ppm, and the treated grain quantities were kept at 25 °C and 65% RH. Samples were taken from each concentration-commodity combination at the day of storage and every 30 d for 6 consecutive months (6 bioassays). The test species were exposed for 14 d to the samples and mortality and reproduction were assessed over this exposure interval. With the exception of T. confusum, 1 ppm of spinosad was highly effective against the remainder of the tested species and provided protection for a period of storage at least 4 months. Although in general, spinosad performance was not very much affected by the grain type, efficacy on maize was less stable over the 6-month period of storage and declined sooner compared to the other commodities. Spinosad almost suppressed progeny production of R. dominica during the storage period, but did not suppress progeny of the other species, since progeny were recorded even 30 d post application especially with the lowest of the tested concentrations. The results of this study indicated that spinosad may provide suitable protection for 6 months against S. oryzae or R. dominica, but is not suitable for long-term protection against T. confusum or C. ferrugineus.     

Quantitative and Qualitative Aspects of Bacterial Communities Associated with Cultures of Chlorella minutissima

Microbiological conditions in 200 L cultures of microalgae Chlorella minutissima in polyethylene sleeves were examined. The influence of addition of antibiotic (nitrofurantoin) was studied. Samples were taken 2, 5, 9, and 14 d after inoculation and were spread on solid Zobell medium and on thiosulfate citrate bile salts sucrose agar for the enumeration of total numbers of bacteria and numbers of presumptive Vibrio bacteria, respectively. Microalgae grew well in the cultures and high numbers of culturable bacteria (about 10⁷ bacteria/mL) were present in all microalgae cultures. Addition of antibiotic in 200‐L cultures of C. minutissima did not result in a significant decrease of total counts of bacteria per unit volume (P > 0.05), while the numbers of presumptive Vibrio were higher in cultures added antibiotic compared with the control treatment (P < 0.05). The numbers of presumptive Vibrio per unit volume and the percentage of fast‐growing bacteria were higher in microalgae supernatant than in noncentrifuged samples. Representative colonies were taken from all samples and in total 649 bacterial strains were isolated during this study. A range of phylotypes was identified by amplification and sequencing of the 16S rDNA gene and phylogenetic trees were constructed. Several members of the Roseobacter clade were dominant among the culturable isolates.     

Insecticide resistance status of the codling moth Cydia pomonella (Lepidoptera: Tortricidae) from Greece

The codling moth Cydia pomonella L. is controlled mostly with chemical insecticides in Greece and control failures have been reported. However, there are no insecticide resistance studies in the country as yet. We examined the insecticide resistance status of 33 and 38 populations of fifth-instar non-diapausing and diapausing larvae, respectively by applying bioassays, biochemical and DNA diagnostics. Diagnostic concentrations of azinphos-methyl, phosalone, deltamethrin, thiacloprid, fenoxycarb, tebufenozide, methoxyfenozide and diflubenzuron were used in bioassays. Almost all populations showed reduced susceptibility to at least one insecticide and approximately half of them to all insecticides examined compared to a laboratory susceptible strain used as reference. However, only one out of six populations tested showed reduced susceptibility in ovicidal tests with fenoxycarb. Cross-resistances were observed among most insecticides, except from the pairs fenoxycarb–phosalone and thiacloprid–phosalone, in non-diapausing larvae. The more obvious biochemical marker associated with the reduced susceptibility observed in both larval instars was elevated cytochrome P₄₅₀ polysubstrate monooxygenases activity, followed by elevated glutathione-S-transferase activity and reduced carboxylesterases activity. Neither sodium channel nor AChE known resistance mutations were found in any of the approximately 1000 individuals of each larval instar screened with diagnostic PCR. Actions for Integrated Resistance Management and application of alternative control methods are discussed.     

Unveiling the influence of the environment on the migration pattern of the Atlantic pomfret (Brama brama) in North‐eastern Atlantic waters

Hydroclimatic variability is one of the main factors that drives inter‐annual changes in fish migration patterns. This study analyses the relationship between climate‐oceanographic factors and migration of the Atlantic pomfret (Brama brama) in NE Atlantic waters. Geo‐referenced catch data from logbooks of longliners operating in European Atlantic waters from 2002 to 2013 were linked to environmental indices at different temporal and spatial scales. Our results point to a strong influence of temperature at 200 m depth as the key factor along with the upwelling in the Galician (NW Iberian) waters. However, sea surface temperature (SST) indirectly affects the geographical display of Atlantic pomfret migration, and large migrations are observed in scenarios of high SSTs in the migratory area (c. above 14.7°C). Migrations are constrained during years when temperatures are below this threshold. A longer time‐series of annual landings (1950–2013) supports this evidence and highlights the significant influence of temperature at 200‐m depth along with the landings of the previous year. Length frequency distributions suggest an increase in size between consecutive seasons supporting the hypothesis that migration is a feeding strategy and a return to tropical waters of origin for spawning. Our study shows that the temperature of intermediate waters is a key variable in determining the northward migration of the Atlantic pomfret whereas density‐dependence and surface climatic conditions trigger secondary effects on the migration pattern of this species.     

Bioencapsulated probiotics increased survival, growth and improved gut flora of turbot (Psetta maxima) larvae

Bacterial diseases are probably the major cause of mortality in aquaculture. The use of probiotics is one of the solutions to manage bacterial infections, by preventing the colonization and exclusion of pathogenic bacteria. The effect of two selected probiotics in turbot (Psetta maxima) larvae was evaluated. Turbot larvae were reared on three different dietary treatments consisting of newly hatched Artemia nauplii from day 16 to 34 post-hatch. Groups A and B were fed with Artemia-containing probiotics FAA and FAB, respectively, and group C was control group. Results indicated that the addition of probiotics increased survival and promoted turbot growth, showing that they were beneficial for the aquaculture of turbot. Moreover, turbot fed with bioencapsulated probiotics attained higher percentages of survival during its development.