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The carbon dioxide (CO2) conversion to useable compounds remains a great contest to scientists, engineers, and environmentalists with regard to the reverse of the oxidative degradation of organics. This conversion is essential for the development of complementary fuels and raw materials for various industries, which in turn will help in avoiding the drastic increase in tropospheric temperature due to greenhouse effect leading to global warming. The solar energy is the earth's essential power source along with the other various forms of energy for example fossil fuels, hydropower, wind, and biomaterials, etc. The final goal is to establish the artificial photosynthesis, which can be replicated thru various chemical reduction techniques of CO2 by employing appropriate photo-, thermal- and electro-catalysts in order to produce different one carbon atom (C1) and higher carbon atoms containing products. Besides, the utilization of clean and sustainable CO2 towards high-value products is of great interest today due to the recognized environmental worries and subsequent lessening of the fossil fuels utilization load to meet the energy demand of mankind. This way, solar energy can directly and/or indirectly be altered and stored in chemical energy form for industrial as well as societal applications. In this article our endeavor is to summarize the advances in CO2 chemical reduction research area till date especially in free radical-based methods such as electrochemical, photochemical and plasma chemical for the development of carbon species up to two carbon (C2) atoms containing products perceived in the chemical reduction of CO2. The author hopes that this piece of work will be helpful to researchers and readers who are focused on the field of CO2.

The carbon dioxide (CO2) conversion to useable compounds remains a great contest to scientists, engineers, and environmentalists with regard to the reverse of the oxidative degradation of organics. This conversion is essential for the development of complementary fuels and raw materials for various industries, which in turn will help in avoiding the drastic increase in tropospheric temperature due to greenhouse effect leading to global warming. The solar energy is the earth's essential power source along with the other various forms of energy for example fossil fuels, hydropower, wind, and biomaterials, etc. The final goal is to establish the artificial photosynthesis, which can be replicated thru various chemical reduction techniques of CO2 by employing appropriate photo-, thermal- and electro-catalysts in order to produce different one carbon atom (C1) and higher carbon atoms containing products. Besides, the utilization of clean and sustainable CO2 towards high-value products is of great interest today due to the recognized environmental worries and subsequent lessening of the fossil fuels utilization load to meet the energy demand of mankind. This way, solar energy can directly and/or indirectly be altered and stored in chemical energy form for industrial as well as societal applications. In this article our endeavor is to summarize the advances in CO2 chemical reduction research area till date especially in free radical-based methods such as electrochemical, photochemical and plasma chemical for the development of carbon species up to two carbon (C2) atoms containing products perceived in the chemical reduction of CO2. The author hopes that this piece of work will be helpful to researchers and readers who are focused on the field of CO2. [ABSTRACT FROM AUTHOR]

Riboflavin (RF) or vitamin B2 is susceptible to photodegradation. Encapsulation of sensitive components by modified yeast cells is a promising method for their widespread usage at industrial scale. Saccharomyces cerevisiae has been introduced as an appropriate carrier of bioactive compounds. The yeast cell comprises a phospholipid membrane that protects the core from the external environment. In this study, the effect of plasmolysis on efficiency of S. cerevisiae cells in encapsulation of RF were investigated. According to the results, plasmolysis increased the encapsulation efficiency (53.85% versus 58.22% for non-plasmolyzed and plasmolyzed yeast cells, respectively) and loading capacity (14.10 and 16.99% for non-plasmolyzed and plasmolyzed yeast cells, respectively). The loaded intact cells had a tied and intertwined structure while the loaded plasmolyzed cells were seen separately in the Scanning Electron Microscope images. According to the Transmission Electron Microscope images, plasmolysis did not destruct the yeast cells and the cell integrity was retained appropriately after the process but it increased the internal space for encapsulation. In X-ray diffraction analysis, RF had a crystalline structure and its encapsulation within the amorphous non-plasmolyzed and plasmolyzed yeast cells led to slight crystallinity in the structure of complex. The observed spectra of functional groups in Fourier Transform Infrared spectroscopy confirmed the successful entrapment of RF in the yeast cells. Plasmolysis depleted the cell contents susceptible to thermal process through which melting point of the yeast cells increased. Owing to the charged surface of yeast cells, they showed a burst release of RF in the simulated stomach (88% for non-plasmolyzed and 84% for plasmolyzed cells) and intestinal fluid (91% and 96% for non-plasmolyzed and plasmolyzed cells, respectively). [ABSTRACT FROM AUTHOR]

ABSTRACT The infection cycle of phage λ terminates in lysis mediated by three types of lysis proteins, each disrupting a layer in the bacterial envelope: the S105 holin, the R endolysin, and the Rz/Rz1 spanin complex targeting the inner membrane, cell wall or peptidoglycan, and the outer membrane, respectively. Video microscopy has shown that in most infections, lysis occurs as a sudden, explosive event at a cell pole, such that the initial product is a less refractile ghost that retains rod-shaped morphology. Here, we investigate the molecular basis of polar lysis using time-lapse fluorescence microscopy. The results indicate that the holin determines the morphology of lysis by suddenly forming two-dimensional rafts at the poles about 100 s prior to lysis. Given the physiological and biochemical similarities between the lambda holin and other class I holins, dynamic redistribution and sudden concentration may be common features of holins, probably reflecting the fitness advantage of all-or-nothing lysis regulation.IMPORTANCEIn this study, we use fluorescent video microscopy to track -green fluorescent protein (GFP)-labeled holin in the minutes prior to phage lysis. Our work contextualizes prior genetic and biochemical data, showing when hole formation starts and where holin oligomers form in relation to the site of lytic rupture. Furthermore, prior work showed that the morphology of lambda-infected cells is characterized by an explosive event starting at the cell pole; however, the basis for this was not clear. This study shows that holin most often oligomerizes at cell poles and that the site of the oligomerization is spatially correlated with the site of lytic blowout. Therefore, the holin is the key contributor to polar lysis morphology for phage lambda.

Across all kingdoms of life, cells secrete an extracellular polymer mesh that in turn feeds back onto them. This entails physical connections between the plasma membrane and the polymer mesh. In plant cells, one connection stands out: the Hechtian strand which, during plasmolysis, reflects the existence of a physical link between the plasma membrane of the retracting protoplast and the cell wall. The Hechtian strand is part of a larger structure, which we call the Hechtian structure, that comprises the Hechtian strand, the Hechtian reticulum and the Hechtian attachment sites. Although it has been observed for more than 100 years, its molecular composition and biological functions remain ill-described. A comprehensive characterization of the Hechtian structure is a critical step towards understanding this plasma membrane-cell wall connection and its relevance in cell signaling. This short review intends to highlight the main features of the Hechtian structure, in order to provide a clear framework for future research in this under-explored and promising field.

A custom design multi‐flying jet plasma torches (MFJPT) reactor was tested for plasmolysis of water vapor and mixtures of water vapor‐carbon dioxide in a series of experimental investigations at various reactor operational parameters. Experimentation plans were applied within the range of induced power (100–300 watts) and various vapor/gas throughputs. The produced gases were analyzed through online gas chromatography. The results of water vapor plasmolysis in two schemes demonstrated the production of 1337 ppm of hydrogen from water vapor/argon and 1665 ppm from applying a water vapor/argon/CO2 combination. Valuable hydrocarbon gases (e.g., Ethane, Ethylene/Acetylene) were generated and detected at higher conversions upon introducing H2O vapor, argon, and CO2 mixtures. The experimental data were trained through machine learning and a Gaussian Process Regression (GPR) model has fitted the data quite well. Ultimately, optimization study outcomes are presented through a color heat‐map for system scaling‐up purposes. [ABSTRACT FROM AUTHOR]

Pulsed electrolysis has become a promising research topic in recent decades due to advances in solid-state semiconductor devices. These technologies have enabled the design and construction of simpler, more efficient, and less costly high-voltage and high-frequency power converters. In this paper, we study high-voltage pulsed electrolysis considering variations in both power converter parameters and cell configuration. Experimental results are obtained for frequency variations ranging from 10 Hz to 1 MHz, voltage changes from 2 V to 500 V, and electrode separations from 0.1 to 2 mm. The results demonstrate that pulsed plasmolysis is a promising method for decomposing water for hydrogen production. [ABSTRACT FROM AUTHOR]

The soil-borne Gram-negative β-proteobacterium Ralstonia solanacearum species complex (RSSC) infects tomato roots through the wounds where secondary roots emerge, infecting xylem vessels. Because it is difficult to observe the behavior of RSSC by a fluorescence-based microscopic approach at high magnification, we have little information on its behavior at the root apexes in tomato roots. To analyze the infection route of a strain of phylotype I of RSSC, R. pseudosolanacearum strain OE1-1, which invades tomato roots through the root apexes, we first developed an in vitro pathosystem using 4 day-old-tomato seedlings without secondary roots co-incubated with the strain OE1-1. The microscopic observation of toluidine blue-stained longitudinal semi-thin resin sections of tomato roots allowed to detect attachment of the strain OE1-1 to surfaces of the meristematic and elongation zones in tomato roots. We then observed colonization of OE1-1 in intercellular spaces between epidermis and cortex in the elongation zone, and a detached epidermis in the elongation zone. Furthermore, we observed cortical and endodermal cells without a nucleus and with the cell membrane pulling away from the cell wall. The strain OE1-1 next invaded cell wall-degenerated cortical cells and formed mushroom-shaped biofilms to progress through intercellular spaces of the cortex and endodermis, infecting pericycle cells and xylem vessels. The deletion of egl encoding β-1,4-endoglucanase, which is one of quorum sensing (QS)-inducible plant cell wall-degrading enzymes (PCDWEs) secreted via the type II secretion system (T2SS) led to a reduced infectivity in cortical cells. Furthermore, the QS-deficient and T2SS-deficient mutants lost their infectivity in cortical cells and the following infection in xylem vessels. Taking together, infection of OE1-1, which attaches to surfaces of the meristematic and elongation zones, in cortical cells of the elongation zone in tomato roots, dependently on QS-inducible PCDWEs secreted via the T2SS, leads to its subsequent infection in xylem vessels. [ABSTRACT FROM AUTHOR]

Carvacrol is the most studied phenolic substance, one of the essential components of thyme. The encapsulation technique can be used to make more stable carvacrol, which has decreased stability due to environmental factors. In this study, it was aimed to encapsulate and characterize carvacrol, which is used in the food, agriculture and pharmaceutical industry, with yeast cells. Yeast cells were pretreated with plasmolysis and carvacrol was encapsulated with both plasmolysed and non-plasmolysed cells. Carvacrol retained was 80.79% in the plasmolysed yeast cells and it was 90.43% in the non-plasmolysed yeast cell. The total amount of phenolic substances in the capsules was determined as to be 138.1 and 146.8 mg GAE/g for plasmolysed and non-plasmolysed yeast cells capsules respectively and the non-plasmolysed yeast capsules exhibited higher antiradical activity compared to the plasmolysed encapsules (PE). In addition, the encapsulation of carvacrol by yeast cells was proved by FTIR technique and structural properties were determined by scanning electron microscope.

Pulsed electrolysis has become a promising research topic in recent decades due to advances in solid-state semiconductor devices. These technologies have enabled the design and construction of simpler, more efficient, and less costly high-voltage and high-frequency power converters. In this paper, we study high-voltage pulsed electrolysis considering variations in both power converter parameters and cell configuration. Experimental results are obtained for frequency variations ranging from 10 Hz to 1 MHz, voltage changes from 2 V to 500 V, and electrode separations from 0.1 to 2 mm. The results demonstrate that pulsed plasmolysis is a promising method for decomposing water for hydrogen production.

Escherichia coli produces extracellular vesicles called outer membrane vesicles (OMVs) by releasing a part of its outer membrane. We previously reported that the combined deletion of nlpI and mlaE, related to envelope structure and phospholipid accumulation in the outer leaflet of the outer membrane, respectively, resulted in the synergistic increase of OMV production. In this study, the analysis of ΔmlaEΔnlpI cells using quick-freeze, deep-etch electron microscopy (QFDE-EM) revealed that plasmolysis occurred at the tip of the long axis in cells and that OMVs formed from this tip. Plasmolysis was also observed in the single-gene knockout mutants ΔnlpI and ΔmlaE. This study has demonstrated that plasmolysis was induced in the hypervesiculating mutant E. coli cells. Furthermore, intracellular vesicles and multilamellar OMV were observed in the ΔmlaEΔnlpI cells. Meanwhile, the secretion of recombinant green fluorescent protein (GFP) expressed in the cytosol of the ΔmlaEΔnlpI cells was more than 100 times higher than that of WT and ΔnlpI, and about 50 times higher than that of ΔmlaE in the OMV fraction, suggesting that cytosolic components were incorporated into outer-inner membrane vesicles (OIMVs) and released into the extracellular space. Additionally, QFDE-EM analysis revealed that ΔmlaEΔnlpI sacculi contained many holes noticeably larger than the mean radius of the peptidoglycan (PG) pores in wild-type (WT) E. coli. These results suggest that in ΔmlaEΔnlpI cells, cytoplasmic membrane materials protrude into the periplasmic space through the peptidoglycan holes and are released as OIMVs.

Escherichia coli produces extracellular vesicles called outer membrane vesicles (OMVs) by releasing a part of its outer membrane. We previously reported that the combined deletion of nlpI and mlaE , related to envelope structure and phospholipid accumulation in the outer leaflet of the outer membrane, respectively, resulted in the synergistic increase of OMV production. In this study, the analysis of Δ mlaE Δ nlpI cells using quick-freeze, deep-etch electron microscopy (QFDE-EM) revealed that plasmolysis occurred at the tip of the long axis in cells and that OMVs formed from this tip. Plasmolysis was also observed in the single-gene knockout mutants Δ nlpI and Δ mlaE. This study has demonstrated that plasmolysis was induced in the hypervesiculating mutant E. coli cells. Furthermore, intracellular vesicles and multilamellar OMV were observed in the Δ mlaE Δ nlpI cells. Meanwhile, the secretion of recombinant green fluorescent protein (GFP) expressed in the cytosol of the Δ mlaE Δ nlpI cells was more than 100 times higher than that of WT and Δ nlpI , and about 50 times higher than that of Δ mlaE in the OMV fraction, suggesting that cytosolic components were incorporated into outer-inner membrane vesicles (OIMVs) and released into the extracellular space. Additionally, QFDE-EM analysis revealed that Δ mlaE Δ nlpI sacculi contained many holes noticeably larger than the mean radius of the peptidoglycan (PG) pores in wild-type (WT) E. coli. These results suggest that in Δ mlaE Δ nlpI cells, cytoplasmic membrane materials protrude into the periplasmic space through the peptidoglycan holes and are released as OIMVs. [ABSTRACT FROM AUTHOR]

Abstract Introduction This study reports on water management in the fields found in arid areas by the improvement of the soil’s water retention capacity. This was done using hydrogels from animal wastes to mitigate the effects of climate change that lead to rapid evaporation of water hence increased desertification rates. Method The modification of the cow dung to hydrogels involves the oxidation of urea or uric acid from chicken dung to form compounds that can undergo a condensation reaction with cellulose in the cow dung. This formed a product with high water retention capacity. Results The materials were characterized using Fourier transform infra-red spectroscopy and thermo-gravimetric analysis which confirmed the derivatization of some functional groups. The thermo-stability was improved, as the degradation temperatures for urea, glycerol, and chicken dung derivatives were 245, 220, and 228 °C, respectively, while the unmodified form was 198 °C. The UV–Vis analysis showed no evidence of starch in the modified material which was also confirmed by Lugol’s test. It was found out that modification had influence on the swelling ability giving it superabsorbent properties with swelling capacities (300 g g−1) within 5 min of moisture exposure plus a high water retention capacity of 90%. Conclusions The application of the modified materials in the growing of some selected plants showed that the moisture content could be sustained for a period of 6 weeks before the plants wilted. This confirms that the modified form of manure has potential application for hydration of plants in arid areas.

The cytoplasm of bacteria is maintained at a higher osmolality than the growth medium, which generates a turgor pressure. The cell membrane (CM) cannot support a large turgor, so there are two possibilities for transferring the pressure to the peptidoglycan cell wall (PGW): (1) the CM could be pressed directly against the PGW, or (2) the CM could be separated from the PGW by a periplasmic space that is isoosmotic with the cytoplasm. There is strong evidence for gram-negative bacteria that a periplasm exists and is isoosmotic with the cytoplasm. No comparable studies have been done for gram-positive bacteria. Here I suggest that a periplasmic space is probably essential in order for the periplasmic proteins to function, including especially the PBPs that remodel the peptidoglycan wall. I then present a semi-quantitative analysis of how teichoic acids could support a periplasm that is isoosmotic with the cytoplasm. The fixed anionic charge density of teichoic acids in the periplasm is ∼0.5 M, which would bring in ∼0.5 M Na+ neutralizing ions. This approximately balances the excess osmolality of the cytoplasm that would produce a turgor pressure of 19 atm. The 0.5 M fixed charge density is similar to that of proteoglycans in articular cartilage, suggesting a comparability ability to support pressure. An isoosmotic periplasm would be especially important for cell division, since it would allow CM constriction and PGW synthesis to avoid turgor pressure.

The cytoplasm of bacteria is maintained at a higher osmolality than the growth medium, which generates a turgor pressure. The cell membrane (CM) cannot support a large turgor, so there are two possibilities for transferring the pressure to the peptidoglycan cell wall (PGW): (1) the CM could be pressed directly against the PGW, or (2) the CM could be separated from the PGW by a periplasmic space that is isoosmotic with the cytoplasm. There is strong evidence for gram-negative bacteria that a periplasm exists and is isoosmotic with the cytoplasm. No comparable studies have been done for gram-positive bacteria. Here I suggest that a periplasmic space is probably essential in order for the periplasmic proteins to function, including especially the PBPs that remodel the peptidoglycan wall. I then present a semi-quantitative analysis of how teichoic acids could support a periplasm that is isoosmotic with the cytoplasm. The fixed anionic charge density of teichoic acids in the periplasm is ∼0.5 M, which would bring in ∼0.5 M Na+ neutralizing ions. This approximately balances the excess osmolality of the cytoplasm that would produce a turgor pressure of 19 atm. The 0.5 M fixed charge density is similar to that of proteoglycans in articular cartilage, suggesting a comparability ability to support pressure. An isoosmotic periplasm would be especially important for cell division, since it would allow CM constriction and PGW synthesis to avoid turgor pressure. [ABSTRACT FROM AUTHOR]

Superoxide dismutases (SODs) are enzymes detoxifying superoxide to hydrogen peroxide while temporal developmental expression and subcellular localisation are linked to their functions. Therefore, we aimed here to reveal in vivo developmental expression, subcellular, tissue‐ and organ‐specific localisation of iron superoxide dismutase 1 (FSD1) in Arabidopsis using light‐sheet and Airyscan confocal microscopy. FSD1‐GFP temporarily accumulated at the site of endosperm rupture during seed germination. In emerged roots, it showed the highest abundance in cells of the lateral root cap, columella, and endodermis/cortex initials. The largest subcellular pool of FSD1‐GFP was localised in the plastid stroma, while it was also located in the nuclei and cytosol. The majority of the nuclear FSD1‐GFP is immobile as revealed by fluorescence recovery after photobleaching. We found that fsd1 knockout mutants exhibit reduced lateral root number and this phenotype was reverted by genetic complementation. Mutant analysis also revealed a requirement for FSD1 in seed germination during salt stress. Salt stress tolerance was coupled with the accumulation of FSD1‐GFP in Hechtian strands and superoxide removal. It is likely that the plastidic pool is required for acquiring oxidative stress tolerance in Arabidopsis. This study suggests new developmental and osmoprotective functions of SODs in plants. FSD1 is localised in plastids, cytoplasm and nucleus and is crucial for endosperm rupture during seed germination under salinity. During hyperosmotic stress FSD1 accumulates in Hechtian strands concomitantly with ROS production, and it has osmoprotective role for plant cells during salinity. [ABSTRACT FROM AUTHOR]

Osmotic adjustment is one of the important mechanisms to adapt to drought and it is the only one which is activated under any level of water stress in the plant cells. Grapevine pollen grains response was tested to osmotic stress in fourteen genotypes, initiated by immersion in 55% or 65% polyethylene glycol solutions without and with addition of potassium chloride, to estimate the expressions of osmotic adjustment. The pollen grain test found differences both in the measurements of projected area cytoplasm and expressions of osmotic adjustment present in the cells. Italian Riesling increased pollen grains cytoplasm in PEG solutions with added KCl much more than other genotypes and had the high values for both expressions of induced and overall osmotic adjustment. The results obtained for expression of induced osmotic adjustment underlined the high K+ accumulation capacity of ‘Italian Riesling’, ‘Burgund mare’ 86 Şt., ‘Muscat d’Adda’ 22 Şt., ‘Muscat Ottonel’ 16 Şt., ‘Pinot gris’ 14 Şt. and ‘Argessis’. The lack of correlation between expressions of induced and intrinsic osmotic adjustment indicated that induced osmotic adjustment expressed by K+ might use different mechanisms that are activated at the time of water stress with different levels of solute accumulation. Because the accumulation of K+ in the cells is important in all developmental stages and, in grape yield and quality, pollen responses to induced osmotic adjustment expressed by K+ could be used as a screening method, for establishing the level of drought sensitivity in the grape varieties under water stress.

The entire crystallization process and the effect of freezing rates on the temperature of spontaneous freezing (TSF) of living onion epidermal cells were analysed in this study. The cells, stained with iodine at a concentration of 1%, were frozen at three different freezing rates, i.e. 2, 1.2, and 0.5°C/min, and were thawed at 5°C/min. The higher freezing rate caused a higher TSF. Moreover, this article presents a method for determining whether a cell is inactivated by a plasmolysis experiment. The results of plasmolysis showed that the formation of ice crystals did not cause fatal mechanical damages to the cells, even when the freezing rate was as slow as 0.1°C/min. Finally, this article also demonstrated the grey-scale changes that occurred in the cells, as evidenced by an image processing technique. This further highlighted the ice crystal growth process and showed the ice crystal content at different locations inside the cells.

Osmotic adjustment is one of the important mechanisms to adapt to drought and it is the only one which is activated under any level of water stress in the plant cells. Grapevine pollen grains response was tested to osmotic stress in fourteen genotypes, initiated by immersion in 55% or 65% polyethylene glycol solutions without and with addition of potassium chloride, to estimate the expressions of osmotic adjustment. The pollen grain test found differences both in the measurements of projected area cytoplasm and expressions of osmotic adjustment present in the cells. Italian Riesling increased pollen grains cytoplasm in PEG solutions with added KCl much more than other genotypes and had the high values for both expressions of induced and overall osmotic adjustment. The results obtained for expression of induced osmotic adjustment underlined the high K+ accumulation capacity of 'Italian Riesling', 'Burgund mare' 86 Şt., 'Muscat d'Adda' 22 Şt., 'Muscat Ottonel' 16 Şt., 'Pinot gris' 14 Şt. and 'Argessis'. The lack of correlation between expressions of induced and intrinsic osmotic adjustment indicated that induced osmotic adjustment expressed by K+ might use different mechanisms that are activated at the time of water stress with different levels of solute accumulation. Because the accumulation of K+ in the cells is important in all developmental stages and, in grape yield and quality, pollen responses to induced osmotic adjustment expressed by K+ could be used as a screening method, for establishing the level of drought sensitivity in the grape varieties under water stress. [ABSTRACT FROM AUTHOR]

Adventitious root cultures of Tarenaya rosea were successfully cryopreserved using the encapsulation-vitrification technique. Histological analysis revealed useful information on the successive steps of cryopreservation. Coupled with complementary histochemical approaches, these studies provided cellular and tissue descriptions of T. rosea root cultures during cryopreservation and contributed to an understanding of cellular stress responses, as well as characterization of the anatomical pattern of root regeneration. The effects of exposure duration to PVS3 solution (0–120 min), unloading treatment (direct and gradual), and recovery medium (liquid and solid) on recovery of cryopreserved roots were investigated. The highest recovery (91%) after cooling in liquid nitrogen (LN) was reached with PVS3 treatment for 90 min, gradual rehydration in unloading solution, and recovery on solid MS medium. The cryopreserved roots showed high multiplication capacity, which was maintained for up to four subcultures. The effect of cryopreservation on root structure was investigated by histological and histochemical studies. Plasmolysis intensified during exposure to loading and PVS3 solutions, but decreased after unloading treatment. The proportion of intercellular spaces increased progressively throughout the cryopreservation protocol, culminating in root cortex disruption. Histochemical analyses revealed polysaccharides, proteins, and both lipidic and pectic substances in intercellular spaces. The vascular cylinder remained intact, ensuring the formation of new roots from the pericycle, showing that proliferative capacity of cryopreserved roots had not diminished. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae is being used for long as a rich source of proteins, sugars, nucleotides, vitamins and minerals. Autolyzed and hydrolyzed yeast biomass has found numerous applications in the health food industry as well as livestock feeds. Here, we have compared three lysis methods for production of yeast lysates using autolysis, plasmolysis (ethyl acetate 1.5%), and enzymatic hydrolysis (Alcalase 0.2%). The efficiency of each process was compared according to soluble solid and protein contents, cell lysis monitoring, and release of intracellular materials, cell viability and microscopic analysis. Results showed that plasmolysis by ethyl acetate was found to be more efficient compared to autolysis, with a higher recovery of yeast extract (YE) content. In comparison, the content of released solids and proteins were higher during the enzymatic hydrolysis using Alcalase compared to autolysis and plasmolysis treatments. The highest decrease in optical density of 600 nm was monitored for the hydrolyzed cells. Besides, we defined "Degree of Leakage (DL)" as a new index of the lysis process, referring to the percentage of total released proteins from the cells and it was estimated to about 65.8%, which represents an appropriate indicator of the cell lysis. The biochemical and biophysical properties of the hydrolyzed yeast product as well as its biological activity (free radical scavenging activity and bacterial binding capacity) suggest that Alcalase could be used to accelerate the lysis of yeast cells and release the valuable intracellular components used for foodstuffs, feed and fermentation media applications. Production of baker's yeast lysates using autolysis, plasmolysis, and enzymatic hydrolysis methods. [ABSTRACT FROM AUTHOR]

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Optimized cryopreservation protocols are essential for the safe, cost-effective and long-term conservation of germplasm of great economic interest, such as Guinea (Petiveria alliacea L.), a medicinal species that synthesizes a great diversity of bioactive substances, among them polysulfides with antitumor activity. Somatic embryos (SEs) produced from in vitro roots were cryopreserved using the V-cryoplate technique. Their viability was measured using the triphenyltetrazolium test and their recovery by counting the number of secondary SEs produced per cryopreserved SE 90 days after liquid nitrogen (LN) exposure. Structural alterations were evaluated qualitatively and quantitatively during the successive stages of the protocol. SEs were dehydrated in 0.5 M sucrose, attached to cryoplates using sodium alginate solution (3%) and treated with PVS2 for different periods. After immersion in LN, SEs were rewarmed in unloading solution (1.2 M sucrose) at room temperature (25 °C) for 20 min. Viability based on the triphenyltetrazolium test was 100% after 15 min of treatment with PVS2 and LN exposure, and recovery, based on multiplication rate, was 21 somatic embryos produced per cryopreserved somatic embryo after 90 days of culture. The histological analysis of cryopreserved somatic embryos showed plasmolysis in the different cell types after treatment with PVS2, with meristematic and parenchymatic cells presenting a higher plasmolysis level. However, after rewarming, the level of plasmolysis decreased over cultivation time, reaching only 2% in meristematic cells after 30 days, indicating the good ability of Petiveria alliacea SEs to develop cryotolerance under the experimental conditions tested. [ABSTRACT FROM AUTHOR]

The infection cycle of phage λ terminates in lysis mediated by three types of lysis proteins, each disrupting a layer in the bacterial envelope: the S105 holin, the R endolysin, and the Rz/Rz1 spanin complex targeting the inner membrane, cell wall or peptidoglycan, and the outer membrane, respectively. Video microscopy has shown that in most infections, lysis occurs as a sudden, explosive event at a cell pole, such that the initial product is a less refractile ghost that retains rod-shaped morphology. Here, we investigate the molecular basis of polar lysis using time-lapse fluorescence microscopy. The results indicate that the holin determines the morphology of lysis by suddenly forming two-dimensional rafts at the poles about 100 s prior to lysis. Given the physiological and biochemical similarities between the lambda holin and other class I holins, dynamic redistribution and sudden concentration may be common features of holins, probably reflecting the fitness advantage of all-or-nothing lysis regulation.IMPORTANCEIn this study, we use fluorescent video microscopy to track -green fluorescent protein (GFP)-labeled holin in the minutes prior to phage lysis. Our work contextualizes prior genetic and biochemical data, showing when hole formation starts and where holin oligomers form in relation to the site of lytic rupture. Furthermore, prior work showed that the morphology of lambda-infected cells is characterized by an explosive event starting at the cell pole; however, the basis for this was not clear. This study shows that holin most often oligomerizes at cell poles and that the site of the oligomerization is spatially correlated with the site of lytic blowout. Therefore, the holin is the key contributor to polar lysis morphology for phage lambda., Competing Interests: The authors declare no conflict of interest.

In this study, hydrogen production via microwave plasma is investigated, analyzed and simulated in a novel way for practical applications. The water vapor when in proximity of a tungsten electrode is modeled for the generation of hydrogen gas. A numerical simulation study is performed using plasma and electromagnetic wave COMSOL modules to analyze the plasmolysis of water vapor within a vacuum concealed reaction vessel entailing a tungsten electrode. A kinetic model is therefore developed to represent the reaction mechanisms and interactions between the species within the plasmolysis reactor. The dynamic results of electron density, electron temperature, plasma rate, and species interactions are extracted through the kinetic model. Within the time domain of 10−16 to 10−14 s, the hydrogen concentration is found to increase to 4.5815 × 10−11 mol/m3 with a corresponding decrease in water vapor concentration of 1.782 × 10−8 mol/m3, respectively. The dynamic variations in the concentrations of other dissociated species are investigated across the geometry of the reaction domain studied, and it is therefore concluded that the tip of the electrode entails the highest species concentrations. • Modeling of microwave hydrogen production via water vapor in COMSOL Multiphysics. • Plasma and electromagnetic frequency domain COMSOL modules utilized. • Hydrogen concentration of 4.5815 × 10−11 mol/m3 achieved within 10−16 to 10−14 s. • Corresponding water vapor concentration reduces by 1.782 × 10−8 mol/m3. [ABSTRACT FROM AUTHOR]

Genes necessary for the survival or reproduction of a cell are an attractive class of antibiotic targets. Studying essential genes by classical genetics, however, is inherently problematic because it is impossible to knock them out. Here, we screened a set of predicted essential genes for growth inhibition using CRISPR-interference (CRISPRi) knockdown in the human pathogen Vibrio cholerae. We demonstrate that CRISPRi knockdown of 37 predicted essential genes inhibits V. cholerae viability, thus validating the products of these genes as potential drug target candidates. V. cholerae was particularly vulnerable to lethal inhibition of the system for lipoprotein transport (Lol), a central hub for directing lipoproteins from the inner to the outer membrane (OM), with many of these lipoproteins coordinating their own essential processes. Lol depletion makes cells prone to plasmolysis and elaborate membrane reorganization, during which the periplasm extrudes into a mega outer membrane vesicle or “MOMV” encased by OM which dynamically emerges specifically at plasmolysis sites. Our work identifies the Lol system as an ideal drug target, whose inhibition could deplete gram-negative bacteria of numerous proteins that reside in the periplasm. [ABSTRACT FROM AUTHOR]

While it is well known that the nature of the applied electric field and the heterogeneity of the tissue can influence the impact of PEF treatment on the plant tissues found in plant-based foods, few studies have investigated the influence of PEF on plant structures that are made up of multiple structurally similar organs. The aim of this study was to understand the effect of pulsed electric fields (PEF), at different electric field strengths (0, 0.3, 0.7 and 1.2 kV/cm) and specific energy (7, 21 and 52 kJ/kg), on a multilayered plant material, with bunching onion bulb tissues being used as a model system. The present study found that carbohydrates leakage was an appropriate index to assess PEF induced damage and that plasmolysis of epidermal cells was a good indicator of plasma membrane integrity after PEF. In addition, electric field strength had a greater impact on the cell integrity than specific energy applied. While other studies have shown that different cell types have different sensitivities to PEF, using plasmolysis as an indicator of cell damage, this study clearly showed that the same PEF treatment conditions had a greater effect on the epidermal cells of the outer scales compared to the inner scales. Hence, while different plant cell types vary in their sensitivities to PEF the spatial location of the same cell type within a complex plant material made up of multiple similar organs, i.e. an onion bulb, can also influence how cells respond to the PEF treatment. Despite PEF induced disruption at the cellular level being detected by carbohydrate leakage, the epidermal cell plasmolysis test and by cryo-scanning electromicroscopy (cryo-SEM), no gross structural changes at the organ level were observed using cryo-SEM or fluorescence microscopy. This study also reports for the first time that PEF treatment can enhance fructan leakage from onion bulbs, which means that PEF treatments have the potential to manipulate the fructan contents of some plant-based foods. Unlabelled Image • Electric field strength had a greater impact on cell membrane permeability than specific energy input. • The effect of PEF treatment on epidermal cells increased from the outer to inner scale leaves. • The effect of PEF on the same tissue type depended on the location of the tissue within the same bulb. • Increasing the electric field strength increased fructan leakage. [ABSTRACT FROM AUTHOR]

Introduction: This study reports on water management in the fields found in arid areas by the improvement of the soil's water retention capacity. This was done using hydrogels from animal wastes to mitigate the effects of climate change that lead to rapid evaporation of water hence increased desertification rates. Method: The modification of the cow dung to hydrogels involves the oxidation of urea or uric acid from chicken dung to form compounds that can undergo a condensation reaction with cellulose in the cow dung. This formed a product with high water retention capacity. Results: The materials were characterized using Fourier transform infra-red spectroscopy and thermo-gravimetric analysis which confirmed the derivatization of some functional groups. The thermo-stability was improved, as the degradation temperatures for urea, glycerol, and chicken dung derivatives were 245, 220, and 228 °C, respectively, while the unmodified form was 198 °C. The UV–Vis analysis showed no evidence of starch in the modified material which was also confirmed by Lugol's test. It was found out that modification had influence on the swelling ability giving it superabsorbent properties with swelling capacities (300 g g−1) within 5 min of moisture exposure plus a high water retention capacity of 90%. Conclusions: The application of the modified materials in the growing of some selected plants showed that the moisture content could be sustained for a period of 6 weeks before the plants wilted. This confirms that the modified form of manure has potential application for hydration of plants in arid areas. [ABSTRACT FROM AUTHOR]

It was recently suggested to end the usage of the term cell wall in microbiology (including prokaryotes and fungi) because it represented an inappropriate and potentially misleading metaphor (Casadevall and Gow, 2022). The analysis of the arguments for such a move from the viewpoint of the plant physiologist indicates that the suggestion is based on misunderstandings, first, of the early history of cell biology and its terminology; second, of the development of modern concepts of cell wall function since the late 19th century; and third, of the nature of metaphors and their role in scientific communication. We conclude that misconceptions concerning cell walls may arise due to pedagogical shortcomings in introducing students to our technical terminology rather than from the fact that part of this terminology originated from metaphors. [ABSTRACT FROM AUTHOR]

Hechtian strands are thread-like structures in plasmolyzed plant cells that connect the cell wall to the plasma membrane. Although these strands were first observed more than 100 years ago, their physiological roles are largely unknown. Here, we used intracellular laser microdissection to examine the effects of disrupting Hechtian strands on plasmolyzed tobacco BY-2 cells. When we focused femtosecond laser pulses on Hechtian strands, targeted disruptions were induced, but no visible changes in cell morphology were detected. However, the calcofluor white signals from β-glucans was detected in plasmolyzed cells with disrupted Hechtian strands, whereas no signals were detected in untreated plasmolyzed cells. These results suggest that Hechtian strands play roles in sensing cell wall integrity.

Across all kingdoms of life, cells secrete an extracellular polymer mesh that in turn feeds back onto them. This entails physical connections between the plasma membrane and the polymer mesh. In plant cells, one connection stands out: the Hechtian strand which, during plasmolysis, reflects the existence of a physical link between the plasma membrane of the retracting protoplast and the cell wall. The Hechtian strand is part of a larger structure, which we call the Hechtian structure, that comprises the Hechtian strand, the Hechtian reticulum and the Hechtian attachment sites. Although it has been observed for more than 100 years, its molecular composition and biological functions remain ill-described. A comprehensive characterization of the Hechtian structure is a critical step towards understanding this plasma membrane-cell wall connection and its relevance in cell signaling. This short review intends to highlight the main features of the Hechtian structure, in order to provide a clear framework for future research in this under-explored and promising field., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

An improved direct transformation method via particle bombardment of split-immature zygotic embryo explants with intact embryonic axis is reported. This method involves abiotic stress (cold treatment and plasmolysis) treatments of explants prepared from immature embryos of 8-10 mm size for improved somatic embryogeneis. Transgenic events were produced using optimized bombardment conditions and selection with hygromycin or glufosinate. Transgenic somatic embryos developed within as little as 4 weeks after bombardment of explants. Transgenic plants were regenerated 4-5 months after bombardment and the entire process from bombardment to T1 seed production took 7-9 months. Plants regenerated from the system were fertile and showed more than 90% heritability of the transgene to the next generation. Transformation frequencies of 5.4 and 2.7% (based on the number of bombarded split-immature embryo explants) were observed with hygromycin and glufosinate selection, respectively. [ABSTRACT FROM AUTHOR]

[Objectives] The research was aimed to study the effect of a nano-iron oxide(ferrihydrite) on maize growth and antioxidant system and to provide theory basis for ferrihydrite used as a new iron fertilizer on maize growth. [Methods] Deionized water(CK1) was set up as control while a series of ferrihydrite, i.e. 10, 20, 50, 100, 200 and 500 mg·L-1 were used as treatments during seed germination. Then seedlings were transferred to 1/2 Hoagland solution without iron(CK2) and with EDTA chelated iron(CK3) while a series of ferrihydrite, i.e. 10, 20, 50, 100, 200 and 500 mg·L-1 with CK2 solution were used as treatments. The biological and physiological indicators as well as cell micro-morphological structures were determined during maize seed germination and seedling growth. [Results] The seed germination experiment results showed that the germination index, the vigor index and the average root length increased significantly by 38.33%, 61.99% and 53.91%, respectively, and the average germination time reduced by 56.63%, when the concentration of ferrihydrite was 20 mg·L-1 as compared with CK1. The seedling growth experiment results showed that the fresh weight of shoot, root of length and chlorophyll content increased significantly by 15.38%, 10.03% and 24.85% as compared with the CK2, when the concentration of ferrihydrite was 20 mg·L-1. Concentration higher than 50 mg·L-1 had damaged maize growth. Ferrihydrite concentrations of less than 20 mg·L-1 increased POD and CAT activities in maize leaves. However, the concentrations of more than 20 mg·L-1 led to the gradual reduction of POD and CAT activities. In addition, results of leaf Fe determination and transmission electron microscopy observation showed that ferrihydrite at the concentration of 10 mg·L-1 could enter the root cells of maize and significantly increased the content of iron in shoot by 75% as compared with CK2. However, higher ferrihydrite concentration of more than 20 mg·L-1 resulted in the plasmolysis of root cell. [Conclusions] The promoting effect of ferrihydrite on seed germination and growth of maize seedlings suggested that low lever ferrihydrite(10-20 mg·L-1) could be used as an alternative for EDTA-Fe, whereas high concentrations of ferrihydrite(≥ 50 mg·L-1) damaged maize growth [ABSTRACT FROM AUTHOR]

Gypsum deposits formed during the middle Miocene Badenian Salinity Crisis (BSC) contain perfectly preserved palynomorphs with fossilised cytoplasms. The nature of the cytoplasm indicates that plasmolysis in a condensed brine solution took place prior to fossilisation. Two forms of plasmolysis are present: concave in zonoporate grains and convex in saccate, inaperturate, pantoporate and colporate specimens. The composition of the palynomorph assemblage is typical for the Miocene European lowland, with plants representing swamp, riparian, mesic and upland communities. Among the dominant taxa are: Pinus/Picea, Taxodium/Glyptostrobus, Ericaceae, Cathaya, Engelhardia and Quercus. The percentages of pollen grains with preserved content are very high for some taxa (Engelhardia, Ericaceae, Fagus, Liquidambar, Potamogeton, Quercus, Taxodium/Glyptostrobus and the Tricolporopollenites pseudocingulum group) and constitute a valuable indicator of the proximity of source vegetation to the depositional basin. Analysis of the pollens shows that, despite the salinity crisis, swamp/riparian and mesic plant communities surrounded the sedimentary basin and the climate remained humid. [ABSTRACT FROM AUTHOR]

* Backgrounds and Aims Because stomata in bryophytes occur on sporangia, they are subject to different developmental and evolutionary constraints from those on leaves of tracheophytes. No conclusive experimental evidence exists on the responses of hornwort stomata to exogenous stimulation. * Methods Responses of hornwort stomata to abscisic acid (ABA), desiccation, darkness and plasmolysis were compared with those in tracheophyte leaves. Potassium ion concentrations in the guard cells and adjacent cells were analysed by X-ray microanalysis, and the ontogeny of the sporophytic intercellular spaces was compared with those of tracheophytes by cryo-scanning electron microscopy. * Key Results The apertures in hornwort stomata open early in development and thereafter remain open. In hornworts, the experimental treatments, based on measurements of >9000 stomata, produced only a slight reduction in aperture dimensions after desiccation and plasmolysis, and no changes following ABA treatments and darkness. In tracheophytes, all these treatments resulted in complete stomatal closure. Potassium concentrations are similar in hornwort guard cells and epidermal cells under all treatments at all times. The small changes in hornwort stomatal dimensions in response to desiccation and plasmolysis are probably mechanical and/or stress responses of all the epidermal and spongy chlorophyllose cells, affecting the guard cells. In contrast to their nascent gas-filled counterparts across tracheophytes, sporophytic intercellular spaces in hornworts are initially liquid filled. * Conclusions Our experiments demonstrate a lack of physiological regulation of opening and closing of stomata in hornworts compared with tracheophytes, and support accumulating developmental and structural evidence that stomata in hornworts are primarily involved in sporophyte desiccation and spore discharge rather than the regulation of photosynthesis-related gaseous exchange. Our results run counter to the notion of the early acquisition of active control of stomatal movements in bryophytes as proposed from previous experiments on mosses. [ABSTRACT FROM AUTHOR]

Cryopreservation stands out as the main strategy to ensure safe and cost efficient long-term conservation of plant germplasm, especially for biotechnological materials. However, the injuries associated with the procedure may result in structural damage and low recovery rates after cooling. Histological analysis provides useful information on the effects of osmotic dehydration, LN exposure, and recovery conditions on cellular integrity and tissue organization, allowing the determination of the critical steps of the cryopreservation protocol and, thus, the use of optimized treatments. Passiflora pohlii Mast. (Passifloraceae) is a native species from Brazil with potential agronomic interest. Recent studies showed the presence of saponins in its roots, which presented antioxidant activity. The goal of this work was to develop a cryopreservation technique for root tips of in vitro-derived plants of P. pohlii using the V-Cryo-plate technique and to characterize the anatomical alterations that occurred during the successive steps of the protocol. Root tips were excised from in vitro plants and precultured before adhesion to cryo-plates and then treated for different periods with the plant vitrification solutions PVS2 or PVS3. Treatment with PVS2 for 45 min resulted in higher recovery (79%) when compared with PVS3 (43%). The greatest number of adventitious roots per cryopreserved explant was also observed after a 45-min exposure to PVS2. Plasmolysis levels were higher in cortical cells of cryopreserved explants treated with PVS2, while pericycle and central cylinder cells were not damaged after this treatment. Thirty days after rewarming, no plasmolysis could be detected, regardless of the experimental conditions. [ABSTRACT FROM AUTHOR]

The entire crystallization process and the effect of freezing rates on the temperature of spontaneous freezing (TSF) of living onion epidermal cells were analysed in this study. The cells, stained with iodine at a concentration of 1%, were frozen at three different freezing rates, i.e. 2, 1.2, and 0.5°C/min, and were thawed at 5°C/min. The higher freezing rate caused a higher TSF. Moreover, this article presents a method for determining whether a cell is inactivated by a plasmolysis experiment. The results of plasmolysis showed that the formation of ice crystals did not cause fatal mechanical damages to the cells, even when the freezing rate was as slow as 0.1°C/min. Finally, this article also demonstrated the grey-scale changes that occurred in the cells, as evidenced by an image processing technique. This further highlighted the ice crystal growth process and showed the ice crystal content at different locations inside the cells. [ABSTRACT FROM AUTHOR]

Natural nanoscale polysaccharide and its application have attracted much attention in recent years. In this study, we report for the first time that a novel naturally occurring capsular polysaccharide (CPS-605) from Lactobacillus plantarum LCC-605, which can self-assemble into spherical nanoparticles with an average diameter of 65.7 nm. To endow CPS-605 with more functionalities, we develop amikacin-functionalized capsular polysaccharide (CPS) nanoparticles (termed CPS-AM NPs) with improved antibacterial and antibiofilm activities against both Escherichia coli and Pseudomonas aeruginosa. They also exhibit faster bactericidal activity than AM alone. The high local positive charge density of CPS-AM NPs facilitates the interaction between the NPs and bacteria, leading to extraordinary bactericidal efficiencies (99.9 % and 100 % for E. coli and P. aeruginosa, respectively, within 30 min) by damaging the cell wall. Very interestingly, CPS-AM NPs exhibit an unconventional antibacterial mechanism against P. aeruginosa , that is, they can induce plasmolysis, along with bacterial cell surface disruption, cell inclusion release and cell death. In addition, CPS-AM NPs exhibit low cytotoxicity and negligible hemolytic activity, showing excellent biocompatibility. The CPS-AM NPs provide a new strategy for the design of next-generation antimicrobial agents that can reduce the working concentration of antibiotics to fight against bacterial resistance. • A novel capsule polysaccharide (CPS-605) is obtained from Lactobacillus plantarum LCC-605. • AM is successfully conjugated with CPS-605 to generate CPS-AM NPs. • CPS-AM NPs significantly reduce the working concentration of amikacin. • CPS-AM NPs exhibit excellent antibacterial activity against Gram-negative strains. • CPS-AM NPs show great biofilm inhibition and disruption abilities. [ABSTRACT FROM AUTHOR]

Plasmolysis is a typical response of plant cells exposed to hyperosmotic stress. The loss of turgor causes the violent detachment of the living protoplast from the cell wall. The plasmolytic process is mainly driven by the vacuole. Plasmolysis is reversible (deplasmolysis) and characteristic to living plant cells. Obviously, dramatic structural changes are required to fulfill a plasmolytic cycle. In the present paper, the fate of cortical microtubules and actin microfilaments is documented throughout a plasmolytic cycle in living cells of green fluorescent protein (GFP) tagged Arabidopsis lines. While the microtubules became wavy and highly bundled during plasmolysis, cortical filamentous actin remained in close vicinity to the plasma membrane lining the sites of concave plasmolysis and adjusting readily to the diminished size of the protoplast. During deplasmolysis, cortical microtubule re-organization progressed slowly and required up to 24 h to complete the restoration of the original pre-plasmolytic pattern. Actin microfilaments, again, recovered faster and organelle movement remained intact throughout the whole process. In summary, the hydrostatic skeleton resulting from the osmotic state of the plant vacuole “overrules” the stabilization by cortical cytoskeletal elements.

Five-week-old tomato plants (Lycopersicon esculentum) cv. Perkoz grown in pots containing garden soil in a growth chamber were submitted to 50 or 150 mM NaCl for 1 h, 2 and 5 days. Tomato leaf anatomy generally did not change after short time salinity, except 5-day-treatment with 150 mM NaCl, where changed cell shape (shrunk and deformed) simultaneously with increased volume of intercellular spaces (IS) were observed. Although leaf hydration (H) depleted only 1 h after 150 mM NaCl treatment both salt concentrations generated two coexisting populations of salt-affected mesophyll cells: (i) slightly-affected (Sl-A) which showed incipient plasmolysis or slightly changed shapes, and (ii) severely-affected (Sv-A) which showed severe plasmolysis; serious deformation of cell shape or disorganization including cell degeneration. In Sl-A cells salinity changed location and shape of chloroplasts which were: more rounded, with oversized starch grains (SG) (2d) or more flat (5d). Salt-mediated changes were becoming more distinguished and pronounced with length of 150 mM NaCl treatment. The amount of salt-affected cells was changing during the experiment and depended on the salt concentration. In 50 mM-treated plants salt-affected cells appeared 1 h after treatment (~40%) and raised up to 78% on 2nd day, however the population of Sl-A cells dominated. In 150 mM NaCl-treated plants the percentage of affected cells raised during the experiment from 75% to 99%. Firstly Sl-A cells dominated, but on the 5th day the majority was Sv-A. Salt-affected cells were distributed quite evenly in palisade or spongy mesophyll, except 2 d after treatment with 50 mM NaCl, when their number was higher in the palisade mesophyll. Sv-A cells in the spongy mesophyll were located mostly near the bundle while in the palisade mesophyll more irregularly. Different susceptibility of cells to salt stress might be the consequence of an unequal distribution of osmotic stress and subsequent ionic stress or physiological state of cells.

Numerous prokaryotes accumulate polyhydroxybutyrate (PHB) intracellularly as a storage material. It has also been proposed that PHB accumulation improves bacterial stress resistance. Cupriavidus necator and its PHB non-accumulating mutant were employed to investigate the protective role of PHB under hypertonic conditions. The presence of PHB granules enhanced survival of the bacteria after exposure to hypertonic conditions. Surprisingly, when coping with such conditions, the bacteria did not utilize PHB to harvest carbon or energy, suggesting that, in the osmotic upshock of C. necator , the protective mechanism of PHB granules is not associated with their hydrolysis. The presence of PHB granules influenced the overall properties of the cells, since challenged PHB-free cells underwent massive plasmolysis accompanied by damage to the cell membrane and the leakage of cytoplasm content, while no such effects were observed in PHB containing bacteria. Moreover, PHB granules demonstrated “liquid-like” properties indicating that they can partially repair and stabilize cell membranes by plugging small gaps formed during plasmolysis. In addition, the level of dehydration and changes in intracellular pH in osmotically challenged cells were less pronounced for PHB-containing cultures, demonstrating the important role of PHB for bacterial survival under hyperosmotic conditions. [ABSTRACT FROM AUTHOR]

Plant genebanks often use cryopreservation to securely conserve clonally propagated collections. Shoot tip cryopreservation procedures may employ vitrification techniques whereby highly concentrated solutions remove cellular water and prevent ice crystallization, ensuring survival after liquid nitrogen exposure. Vitrification solutions can be comprised of a combination of components that are either membrane permeable or membrane impermeable within the timeframe and conditions of cryoprotectant exposure. In this study, the osmotic responses of sweet potato [ Ipomoea batatas (L.) Lam.] suspension cell cultures were observed after treatment with plant vitrification solution 2 [PVS2; 15% ( v/v) dimethyl sulfoxide (DMSO), 15% ( v/v) ethylene glycol, 30% ( v/v) glycerol, 0.4 M sucrose], plant vitrification solution 3 (PVS3; 50% ( v/v) glycerol, 50% ( w/v) sucrose), and their components at 25 and 0°C, as well as cryoprotectant solution, PGD (10% ( w/v) PEG 8000, 10% ( w/v) glucose, 10% ( v/v) DMSO) at 25°C. At either 25 or 0°C, sweet potato cells plasmolyzed after exposure to PVS2, PVS3, and PGD solutions as well as the PVS2 and PVS3 solution components. Cells deplasmolyzed when the plasma membrane was permeable to the solutes and when water re-entered to maintain the chemical potential. Sweet potato suspension cells deplasmolyzed in the presence of 15% ( v/v) DMSO or 15% ( v/v) ethylene glycol. Sweet potato plasma membranes were more permeable to DMSO and ethylene glycol at 25°C than at 0°C. Neither sucrose nor glycerol solutions showed evidence of deplasmolysis after 3 h, suggesting low to no membrane permeability of these components in the timeframes studied. Thus, vitrification solution PVS2 includes components that are more membrane permeable than PVS3, suggesting that the two vitrification solutions may have different cryoprotectant functions. PGD includes DMSO, a permeable component, and likely has a different mode of action due to its use in two-step cooling procedures. [ABSTRACT FROM AUTHOR]

In plant cells, molecular connections link the cell wall-plasma membrane-actin cytoskeleton to form a continuum. It is hypothesized that the cell wall provides stable anchor points around which the actin cytoskeleton remodels. Here we use live cell imaging of fluorescently labelled marker proteins to quantify the organization and dynamics of the actin cytoskeleton and to determine the impact of disrupting connections within the continuum. Labelling of the actin cytoskeleton with green fluorescent protein (GFP)-fimbrin actin-binding domain 2 (FABD2) resulted in a network composed of fine filaments and thicker bundles that appeared as a highly dynamic remodelling meshwork. This differed substantially from the GFP-Lifeact-labelled network that appeared much more sparse with thick bundles that underwent 'simple movement', in which the bundles slightly change position, but in such a manner that the structure of the network was not substantially altered during the time of observation. Label-dependent differences in actin network morphology and remodelling necessitated development of two new image analysis techniques. The first of these, 'pairwise image subtraction', was applied to measurement of the more rapidly remodelling actin network labelled with GFP-FABD2, while the second, 'cumulative fluorescence intensity', was used to measure bulk remodelling of the actin cytoskeleton when labelled with GFP-Lifeact. In each case, these analysis techniques show that the actin cytoskeleton has a decreased rate of bulk remodelling when the cell wall-plasma membrane-actin continuum is disrupted either by plasmolysis or with isoxaben, a drug that specifically inhibits cellulose deposition. Changes in the rate of actin remodelling also affect its functionality, as observed by alteration in Golgi body motility. [ABSTRACT FROM AUTHOR]

Plasmolysis of hypocotyl cells of transgenic Arabidopsis thaliana and Nicotiana benthamiana diminishes the dynamics of the remodeling of the endoplasmic reticulum (ER) in the central protoplast, namely that withdrawn from the cell wall, and more persistent cisternae are formed, yet little change in the actin network in the protoplast occurs. Also, protein flow within the ER network in the protoplast, as detected with fluorescence recovery after photobleaching (FRAP), is not affected by plasmolysis. After plasmolysis, another network of strictly tubular ER remains attached to the plasma membrane-wall interface and is contained within the Hechtian strands and reticulum. FRAP studies indicate that protein flow within these ER tubules diminishes. Actin is largely absent from the Hechtian reticulum and the ER becomes primarily associated with altered, branched microtubules. The smaller volume of the central protoplast is accompanied by decreased movement rates of tubules, cisternae, and spheroid organelles, but this reduced movement is not readily reversed by the increase in volume that accompanies deplasmolysis. [ABSTRACT FROM AUTHOR]

A three-domain pressure-volume relationship (PV curve) was studied in relation to leaf anatomical structure during dehydration in the grey mangrove, Avicennia marina. In domain 1, relative water content (RWC) declined 13% with 0.85 MPa decrease in leaf water potential, reflecting a decrease in extracellular water stored primarily in trichomes and petiolar cisternae. In domain 2, RWC decreased by another 12% with a further reduction in leaf water potential to −5.1 MPa, the turgor loss point. Given the osmotic potential at full turgor (−4.2 MPa) and the effective modulus of elasticity (~40 MPa), domain 2 emphasized the role of cell wall elasticity in conserving cellular hydration during leaf water loss. Domain 3 was dominated by osmotic effects and characterized by plasmolysis in most tissues and cell types without cell wall collapse. Extracellular and cellular water storage could support an evaporation rate of 1 mmol m−2s−1 for up to 54 and 50 min, respectively, before turgor loss was reached. This study emphasized the importance of leaf anatomy for the interpretation of PV curves, and identified extracellular water storage sites that enable transient water use without substantive turgor loss when other factors, such as high soil salinity, constrain rates of water transport. [ABSTRACT FROM AUTHOR]

This work analyzes the effect of Pulsed Electric Fields (PEF) as a pre-treatment of the osmotic dehydration (OD) of kiwifruit ( Actinidia deliciosa cv Hayward ) in the internal structure and in the internal water transport. PEF pre-treatments were done using three PEF intensities (100, 250 and 400 V/cm) and analyzed by TD-NMR. The OD was carried out by immersing the samples in 61.5% sucrose solution at 25 °C. The application of a PEF pre-treatment before the OD produces a process of plasmolysis proportional to the electric field applied. It is because the PEF removes the mobile charges of the medium, such as electrolytes, organic acids, amino acids; Ca + 2 is the major culprit of the plasmolysis because it fixes some of the junctions of the microtubules between the cell wall and the membrane. Therefore, a previous plasmolysis produces an increase in the apoplastic transport increasing the rate of dehydration. Industrial relevance This research describes the effect of the PEF pre-treatment of osmotic dehydration in the microstructure and in the internal water liquid phases transports of the kiwifruit tissue by using TD-NMR. The results of this research have demonstrated that the application of an electric field prior to the osmotic dehydration produces a process of plasmolysis more the greater the electric field applied, due to the elimination of the mobile charges of the medium and mainly affecting the internal transports. Therefore, PEF pre-treatment accelerate the OD treatment preserving the structure and consequently remaining the life cycles, necessaries to obtain a long shelf life of the product. It has been demonstrated the useful of the TD-NMR as a technique able to analyzed the effect of PEF at a microstructural degree. [ABSTRACT FROM AUTHOR]