Osmotic adjustments support growth of poplar cultured cells under high concentrations of carbohydrates.

KEY MESSAGE: Poplar callus maintained a specific difference in osmotic potential with respect to media when supplemented with different carbohydrate concentrations. This balance in osmotic potential guaranteed the growth capacity. Osmotic stress is caused by several abiotic factors such as drought, salinity, or freezing. However, the threshold of osmotic potential that allows the growth under stress conditions has not been thoroughly studied. In this study, different levels of osmotic stress in Populus alba (L.) callus have been induced with the addition of mannitol or sorbitol in the medium (from 0 to 500 mM). The key factor for preserving the growth was observed to be the restoration of a constant difference in osmotic potential between callus and medium for all the tested conditions. The osmotic adjustments were primarily achieved with the uptake of mannitol or sorbitol from the media considering their chemical properties instead of their biological functions. The decrease in water content (from - 1 to - 10% after 21 days) and mineral elements, such as potassium, calcium, and magnesium, together with the alterations in cell morphology, did not show negative effects on growth. The activity of sorbitol dehydrogenase was detected for the first time in poplar (+ 4.7 U l-1 in callus treated with sorbitol compared to control callus). This finding suggested the importance of choosing carefully the molecules used to exert osmotic stress for separating the dual function of carbohydrates in osmotic adjustments and cell metabolism.

High vacuum-assisted extraction affects virgin olive oil quality: Impact on phenolic and volatile compounds.

High vacuum technology has been incorporated into a new assisted extraction system applied to virgin olive oil (VOO) processing, which was tested at a lab-scale pilot plant to evaluate its impact on the physicochemical properties of the olive paste and oil. The vacuum system induced changes in the mechanical and structural properties of the olive cells, improving the coalescence of the oil droplets due to substantial cellular and intracellular mass transfer during the process, as shown by cryo-scanning electron microscopy (Cryo-SEM) analysis. The effects on the quality characteristics of VOOs extracted from three cultivars at different malaxation temperatures were evaluated. A significant increase in the phenolic content, from 25.2% to 48.6%, was observed. The content of volatile compounds responsible for the VOO flavor decreased as a function of malaxation temperature. The reduction of some volatile molecules related to the VOO off-flavor (ethanol, ethyl acetate and acetic acid) was also shown.

Cryo-scanning electron microscopy investigation of the Octopus Vulgaris arm structures for the design of an octopus-like arm artefact.

Octopus vulgaris is a cephalopod of the Octopodidae family. It has four pairs of arms and two rows of suckers which perform many functions, including bending and elongation. For this reason the octopus was chosen as model to develop a new generation of soft-body robots. In order to explain some of the fine structures of the octopus arm in relation to its specific ability, we examined the external and internal structures of O. vulgaris arms in a frozen-hydrated state using cryo-scanning electron microscopy. The arms showed skin with a very complex design that is useful to elongation, and a pore pattern distribution on their surface which is functional to cutaneous oxygen uptake. The analysis of freeze-fractured frozen-hydrated arm samples allowed us to describe the developmental differences in the relative proportion of the areas of axial nerve cord, intrinsic and extrinsic musculature, in relation to the growth of the arms and of the increase in functional capability. In the suckers, we analyzed the shedding mechanisms in the outer part of the infundibulum and described the outer and inner characteristics of the denticles, showing in detail their pore system, which is fundamental for their ability to explore the environment. These results are discussed by considering their possible application in the design of new octopus-like artefacts, which will be able to take advantage of some of these ultrastructure characteristics and achieve advanced bioinspired functionalities.

Gas exchange and foliage characteristics of two poplar clones grown in soil amended with industrial waste.

Plants can remove or immobilize various environmental contaminants; however, little is known about the physiological mechanisms underlying responses to soil amendment with biosolids contaminated with heavy metals. We investigated the responses of cuttings of hybrid poplar clones Eridano and I-214 grown for a season in soil amended with nutrient-rich organic material from tanneries, which contains potentially toxic amounts of heavy elements. Plant growth traits, gas exchange parameters, stomatal density and leaf layer thickness of frozen-hydrated leaves, and foliar concentrations of heavy metals and nitrogen were determined. Overall, soil amendment increased net assimilation rate and growth, but the cuttings accumulated only small quantities of heavy metal soil contaminants.

Flash thermal conditioning of olive pastes during the olive oil mechanical extraction process: impact on the structural modifications of pastes and oil quality.

The quality of virgin olive oil (VOO) is strictly related to the concentrations of phenolic and volatile compounds, which are strongly affected by the operative conditions of the VOO mechanical extraction process. The aim of this work is to study the impact of a new technology such as flash thermal conditioning (FTC) on olive paste structural modification and on VOO quality. The evaluation of olive paste structure modification by cryo-scanning electron microscopy (cryo-SEM) showed that the application of FTC after crushing produces significant differences in terms of the breaking of the parenchyma cells and aggregation of oil droplets in comparison to the crushed pastes. The virgin olive oil flash thermal conditioning (VOO-FTC) featured a higher concentration of volatile compounds compared to that in the control, particularly of all saturated and unsaturated aldehydes and esters, whereas the phenolic concentration was higher in VOO obtained from the traditional process (VOO-C).

Compositional and tissue modifications induced by the natural fermentation process in table olives.

Olive fruits contain high concentrations of phenols that include phenolic acids, phenolic alcohols, flavonoids, and secoiridoids. The final concentration of phenols is strongly affected by brine conditions. The factors involved in modification by brine are still partially unknown and can include hydrolysis of secoiridoid glucosides and the release of hydrolyzed products. In this study olives from various Italian cultivars were processed by natural fermentation (e.g., without a preliminary treatment of olives with NaOH) using a selected Lactobacillus strain. Processed olives are characterized by a low phenolic concentration of phenols, consisting mainly of phenyl alcohols, verbascoside, and the dialdehydic form of decarboxymethylelenolic acid linked to (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA), whereas a high level of phenols occurs in olive brine from all the cultivars studied. Olives of the Coratina cultivar, control and with fermentation by Lactobacillus pentosus 1MO, were analyzed in a frozen hydrated state by cryo scanning electron microscopy and energy-dispersive X-ray microanalysis, on both surface and transversal freeze-fracture planes. Structural modifications, found in olives after fermentation, may explain the phenol release in brine.

Ultrastructural characterization of antennal sensilla and immunocytochemical localization of a chemosensory protein in Carausius morosus Brünner (Phasmida: Phasmatidae).

The aim of this work was to investigate the olfactory system of the walking stick insect, Carausius morosus. Morphological, ultrastructural and immunocytochemical studies of adult female antennae were conducted by scanning and transmission electron microscopy. Extensive cross-section series were made through the last antennal segment to define the cuticular apparatus, wall pore distribution and the number of innervating receptor neurons of each sensillum type. Single-walled wall pore sensilla occur in three subtypes: (i) with 27 or 28 branched receptor neurons, (ii) with two branched neurons and (iii) with one or two unbranched neurons, respectively. Double-walled wall pore sensilla were found in two subtypes with spoke channels, one with four unbranched neurons, the other with two unbranched neurons. One terminal pore sensillum was found, showing two cavities within the hair and being innervated by six sensory cells. Immunocytochemical experiments were performed to show the localization of a 19 kDa soluble protein found in the chemosensory organs of C. morosus. This protein shows an amino acid sequence homologous to the family of chemosensory proteins (CSP). The polyclonal antibody raised against the purified protein (CSP-cmA) showed, for the first time in CSPs, a strong labeling in olfactory sensilla, specifically in the sensillum lymph surrounding the dendritic branches of SW-WP sensilla and in the uninnervated lumen between the two concentric walls of DW-WP type 1 sensilla.

Physiological and morphological responses of olive plants to ozone exposure during a growing season.

We studied physiological (gas exchange and stomatal aperture) and morphological (individual leaf area and stomatal density) responses in leaves of five-year-old olive plants (Olea europaea L. cvs. Frantoio and Moraiolo) exposed to filtered air containing < 3 ppb O(3) or 100 ppb O(3) for 5 h day(-1) for 120 days in fumigation chambers. After 100 days of treatment, leaf drop and development of necrotic spots were observed in O(3)-fumigated plants of Moraiolo but not of Frantoio. Significant reductions in photosynthetic activity (57%) and stomatal conductance (69%) were detected in O(3)-fumigated plants of Frantoio compared with control plants. In O(3)-fumigated plants of Moraiolo, the decrease in photosynthetic activity (17%) was not statistically significant, but a significant reduction in stomatal conductance (40%) was observed. In both cultivars, leaves that developed after exposure to O(3) showed decreased stomatal aperture (63.6 and 54.8% with respect to the Frantoio and Moraiolo controls, respectively) and one-sided leaf area, and increased stomatal density compared with control leaves. Actual transpiring stomatal surface decreased substantially in both Frantoio (59.8%) and Moraiolo (56.3%) in response to O(3) treatment. Relative transpiring stomatal surface (RTSS) in Frantoio decreased from 0.54 (control) to 0.27% (O(3) treated) of total leaf surface. The corresponding values for Moraiolo were 0.79 and 0.42%. However, because the RTSS of Moraiolo leaves in the O(3) treatment was 0.42 versus 0.27% in Frantoio, the potential uptake of O(3) was higher for Moraiolo plants than for Frantoio plants. The large O(3)-induced reduction in transpiring stomatal surface in both cultivars could have significant effects on olive productivity in the Mediterranean area, where high O(3) concentrations persist for long periods during the year.