Search

While the treatment of red grapes with pulsed electric fields (PEFs) has been widely investigated, white grapes have been little studied to date. This work, therefore, investigates the PEF treatment of white grapes (Thompson Seedless) by applying different field strengths (2 to 6 kV/cm), resulting in different specific energy inputs (2.5 to 22.5 kJ/kg). Numerous parameters of the whole grapes and the extracted juice were analyzed, including the total phenolic index (TPI), reducing sugars, juice yields, and changes in color and texture. Changes in the aroma profile were investigated using instrument-based and sensory analysis. The most striking effect seen in the PEF-treated samples was the visual change in the grape skin, specifically browning. Depending on the field strength, the treated grapes showed a 26% to 50% reduction in crunchiness. No significant changes were measured in the juice yields compared with the control, although at E = 4.5 kV/cm there was an increase in reducing sugars of up to 11% (220.97 g/L) and a 30% higher TPI (398.90 mg/L). Aroma differences were not detected between the control and the treated grapes, meaning that consumers should not expect negative sensory effects in the juice of treated white grapes. [ABSTRACT FROM AUTHOR]

Cells of a cell-wall deficient line (cw15-type) of Chlamydomonas reinhardtii and of the corresponding wild type were grown during repetitive light-dark cycles. In a direct comparison, both lines showed approximately the same relative biomass increase during light phase but the cw-line produced significantly more, and smaller, daughter cells. Throughout the light period the average cellular starch content, the cellular chlorophyll content, the cellular rate of dark respiration, and the cellular rate of photosynthesis of the cw-line was lower. Despite this, several non-cell volume related parameters like the development of starch content per cell volume were clearly different over time between the strains. Additionally, the chlorophyll-based photosynthesis rates were 2-fold higher in the mutant than in the wild-type cells, and the ratio of chlorophyll a to chlorophyll b as well as the light-saturation index were also consistently higher in the mutant cells. Differences in the starch content were also confirmed by single cell analyses using a sensitive SHG-based microscopy approach. In summary, the cw15-type mutant deviates from its genetic background in the entire cell physiology. Both lines should be used in further studies in comparative systems biology with focus on the detailed relation between cell volume increase, photosynthesis, starch metabolism, and daughter cell productivity. Keywords: cell wall deficient mutant, diurnal rhythm, nonlinear microscopy, photosynthesis, single-cell analysis. Les cellules provenant d'une lignee de Chlamydomonas reinhardtii depourvue de paroi cellulaire (type cw15) et des cellules sauvages correspondantes ont ete cultivees durant des cycles lumiere-noirceur repetes. Par comparaison directe, les deux lignees presentaient approximativement la meme augmentation de biomasse relative durant la phase eclairee mais la lignee cw produisait significativement plus de cellules filles et de plus petite taille. Tout au long de la periode de lumiere, le contenu cellulaire moyen d'amidon, le contenu cellulaire en chlorophylle, le taux cellulaire de respiration mitochondriale et le taux cellulaire de photosynthese de la lignee cw etaient plus faibles. Malgre cela, plusieurs parametres non relies au volume de la cellule, comme le developpement du contenu en amidon par cellule, differaient clairement en fonction du temps entre les deux lignees. De plus, les taux de photosynthese a partir de la chlorophylle etaient deux fois plus eleves chez le mutant que chez les cellules sauvages; le rapport de chlorophylle a sur la chlorophylle b ainsi que l'indice de saturation lumineuse etaient aussi systematiquement plus eleves dans les cellules mutantes. Les differences dans le contenu en amidon ont aussi ete confirmees par des analyses sur cellules individuelles au moyen d'une approche sensible basee sur la microscopie a generation de seconde harmonique. En resume, le mutant cw-15 devie de son background genetique sur le plan de la physiologie entiere de la cellule. Les deux lignees devraient etre utilisees dans les futures etudes du domaine de la biologie comparative des systemes, en mettant l'emphase sur la relation detaillee que existe entre l'accroissement de volume cellulaire, la photosynthese, le metabolisme de l'amidon et la productivite des cellules filles. [Traduit par la Redaction] Mots-cles : mutant depourvu de paroi cellulaire, rythme diurne, microscopie non-lineaire, photosynthese, analyse sur cellules individuelles., Introduction Numerous studies have indicated that the natural light-dark rhythm is one of the most important signals in plant and algal physiology (see e.g., Stitt and Zeeman 2012). Under laboratory [...]

Abstract Background Previous results with the planar robot MIT-MANUS demonstrated positive benefits in trials with over 250 stroke patients. Consistent with motor learning, the positive effects did not generalize to other muscle groups or limb segments. Therefore we are designing a new class of robots to exercise other muscle groups or limb segments. This paper presents basic engineering aspects of a novel robotic module that extends our approach to anti-gravity movements out of the horizontal plane and a pilot study with 10 outpatients. Patients were trained during the initial six-weeks with the planar module (i.e., performance-based training limited to horizontal movements with gravity compensation). This training was followed by six-weeks of robotic therapy that focused on performing vertical arm movements against gravity. The 12-week protocol includes three one-hour robot therapy sessions per week (total 36 robot treatment sessions). Results Pilot study demonstrated that the protocol was safe and well tolerated with no patient presenting any adverse effect. Consistent with our past experience with persons with chronic strokes, there was a statistically significant reduction in tone measurement from admission to discharge of performance-based planar robot therapy and we have not observed increases in muscle tone or spasticity during the anti-gravity training protocol. Pilot results showed also a reduction in shoulder-elbow impairment following planar horizontal training. Furthermore, it suggested an additional reduction in shoulder-elbow impairment following the anti-gravity training. Conclusion Our clinical experiments have focused on a fundamental question of whether task specific robotic training influences brain recovery. To date several studies demonstrate that in mature and damaged nervous systems, nurture indeed has an effect on nature. The improved recovery is most pronounced in the trained limb segments. We have now embarked on experiments that test whether we can continue to influence recovery, long after the acute insult, with a novel class of spatial robotic devices. This pilot results support the pursuit of further clinical trials to test efficacy and the pursuit of optimal therapy following brain injury.

The essential mineral nutrient potassium (K+) is the most impor- tant inorganic cation for plants and is recognized as a limiting factor for crop yield and quality. Nonetheless, it is only partially understood how K+ contributes to plant productivity. K+ is used as a major active solute to maintain turgor and to drive irreversible and reversible changes in cell volume. K+ also plays an important role in numerous metabolic processes, for example, by serving as an essential cofactor of enzymes. Here, we provide evidence for an additional, previously unrecognized role of K+ in plant growth. By combining diverse experimental approaches with computational cell simulation, we show that K+ circulating in the phloem serves as a decentralized energy storage that can be used to overcome local energy limitations. Posttranslational modification of the phloem-expressed Arabidopsis K+ channel AKT2 taps this "potassium battery," which then efficiently assists the plasma membrane H+-ATPase in energizing the transmembrane phloem (re) loading processes. [ABSTRACT FROM AUTHOR]

The cell cycle is a complex sequence of events by which cells grow and divide mitotically or meiotically. Mitosis results in the generation of two identical daughter cells, while meiosis generates gametes as a prerequisite for sexual reproduction. To study the localization and dynamics of proteins involved in the regulation and proceeding of the cell cycle, life cell imaging of proteins fused to fluorescent tags can be performed. However, in some cases this approach cannot be applied, e.g., due to low fluorescence intensity, fast bleaching, or degradation of recombinant proteins by the proteasome pathway. Instead, immunolabeling with protein-specific antibodies offers a useful approach for the analysis of intact cells. Alternatively, immunolabeling can also be applied to isolated and/or flow-sorted nuclei of particular cell cycle stages (G1, S, and G2) or of different endopolyploidy levels. The following chapter will detail indirect immunolabeling protocols to analyze the subcellular localization and distribution of cell cycle-specific proteins in Arabidopsis thaliana., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The cell cycle is a complex sequence of events by which cells grow and divide mitotically or meiotically. Mitosis results in the generation of two identical daughter cells, while meiosis generates gametes as a prerequisite for sexual reproduction. To study the localization and dynamics of proteins involved in the regulation and proceeding of the cell cycle, life cell imaging of proteins fused to fluorescent tags can be performed. However, in some cases this approach cannot be applied, e.g., due to low fluorescence intensity, fast bleaching or degradation of recombinant proteins by the proteasome pathway. Instead, immunolabeling with protein-specific antibodies represents a useful approach for the analysis of intact cells. Alternatively, immunolabeling can also be applied to isolated and/or flow-sorted nuclei of particular cell cycle stages (G1, S, and G2) or of different endopolyploidy levels. This chapter details indirect immunolabeling protocols to analyze the subcellular localization and distribution of cell cycle-specific proteins in Arabidopsis thaliana.

Potassium (K (+) ) is an important nutrient for plants. It serves as a cofactor of various enzymes and as the major inorganic solute maintaining plant cell turgor. In a recent study, an as yet unknown role of K (+) in plant homeostasis was shown. It was demonstrated that K (+) gradients in vascular tissues can serve as an energy source for phloem (re)loading processes and that the voltage-gated K (+) channels of the AKT2-type play a unique role in this process. The AKT2 channel can be converted by phosphorylation of specific serine residues (S210 and S329) into a non-rectifying channel that allows a rapid efflux of K (+) from the sieve element/companion cells (SE/CC) complex. The energy of this flux is used by other transporters for phloem (re)loading processes. Nonetheless, the results do indicate that post-translational modifications at S210 and S329 alone cannot explain AKT2 regulation. Here, we discuss the existence of multiple post-translational modification steps that work in concert to convert AKT2 from an inward-rectifying into a non-rectifying K (+) channel.