scholarly journals Intracellular mass density increase is accompanying but not sufficient for stiffening and growth arrest of yeast cells

2018 ◽  
Author(s):  
Shada Abuhattum ◽  
Kyoohyun Kim ◽  
Titus M. Franzmann ◽  
Anne Eßlinger ◽  
Daniel Midtvedt ◽  
...  
Keyword(s):  
Mass Density ◽  
Physical And Mechanical Properties ◽  
Optical Diffraction ◽  
Yeast Cells ◽  
Cellular Mechanisms ◽  
Optical Diffraction Tomography ◽  
Long Time ◽  
Metabolic Arrest ◽  
Macromolecular Architecture ◽  
Physical And Chemical

AbstractMany organisms, including yeast cells, bacteria, nematodes and tardigrades, endure harsh environmental conditions, such as nutrient scarcity, or lack of water and energy for a remarkably long time. The rescue programs that these organisms launch upon encountering these adverse conditions include reprogramming their metabolism in order to enter a quiescent or dormant state in a controlled fashion. Reprogramming coincides with changes in the macromolecular architecture and changes in the physical and mechanical properties of the cells. However, the cellular mechanisms underlying the physical-mechanical changes remain enigmatic. Here, we induce metabolic arrest of yeast cells by lowering their intracellular pH. We then determine the differences in the intracellular mass density and stiffness of active and metabolically arrested cells using optical diffraction tomography and atomic force microscopy. We show that an increased intracellular mass density is associated with an increase in stiffness when the growth of yeast is arrested. However, increasing the intracellular mass density alone is not sufficient for maintenance of the growth-arrested state in yeast cells. Our data suggest that the cytoplasm of metabolically arrested yeast displays characteristics of solid. Our findings constitute a bridge between the mechanical behavior of the cytoplasm and the physical and chemical mechanisms of metabolically arrested cells with the ultimate aim of understanding dormant organisms.

scholarly journals Correlative all-optical quantification of mass density and mechanics of sub-cellular compartments with fluorescence specificity

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Raimund Schlüßler ◽  
Kyoohyun Kim ◽  
Martin Nötzel ◽  
Anna Taubenberger ◽  
Shada Abuhattum ◽  
...  
Keyword(s):  
Mass Density ◽  
Optical Diffraction ◽  
Physical Parameters ◽  
Implicit Assumption ◽  
Optical Diffraction Tomography ◽  
Quantitative Measurements ◽  
All Optical ◽  
Novel Method ◽  
Cellular Compartments ◽  
Longitudinal Modulus

Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples - so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample - a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.

scholarly journals Optical quantification of intracellular mass density and cell mechanics in 3D mechanical confinement

Soft Matter ◽  
2021 ◽  
Author(s):  
Sadra Bakhshandeh ◽  
Hubert M. Taïeb ◽  
Raimund Schlüßler ◽  
Kyoohyun Kim ◽  
Timon Beck ◽  
...  
Keyword(s):  
Cell Mechanics ◽  
Mass Density ◽  
Optical Diffraction ◽  
Diffraction Tomography ◽  
Brillouin Spectroscopy ◽  
Optical Diffraction Tomography

Optical quantification of intracellular mass density using optical diffraction tomography (ODT) and cell mechanics using Brillouin spectroscopy under 3D mechanical confinement.

scholarly journals Quantitative imaging of Caenorhabditis elegans dauer larvae during cryptobiotic transition using optical diffraction tomography

2021 ◽  
Author(s):  
Kyoohyun Kim ◽  
Vamshidhar R. Gade ◽  
Teymuras V. Kurzchalia ◽  
Jochen Guck
Keyword(s):  
Caenorhabditis Elegans ◽  
Material Properties ◽  
Structural Changes ◽  
Mass Density ◽  
Quantitative Imaging ◽  
Optical Diffraction ◽  
Physical Analysis ◽  
Diffraction Tomography ◽  
Optical Diffraction Tomography ◽  
Dauer Larvae

Upon starvation or overcrowding, the nematode Caenorhabditis elegans enters diapause by forming a dauer larva. This larva can further transit into an anhydrobiotic state and survive harsh desiccation. We previously identified the genetic and biochemical pathways essential for survival — but without an accompanying physical model, the mechanistic understanding of this amazing phenomenon will remain inadequate. Neither microscopic investigation of structural changes upon entry into anhydrobiosis nor the most basic quantitative characterization of material properties of living desiccated larvae, however, have been feasible, due to lack of appropriate techniques. Here, we employed optical diffraction tomography (ODT) to quantitatively assess the internal mass density distribution of living larvae in the reproductive and diapause stages. More importantly, ODT allowed for the first time physical analysis of desiccated dauer larvae: their mass density was significantly increased in the anhydrobiotic state. We also applied ODT on different mutants that are sensitive to desiccation. Remarkably, one of them displayed structural abnormalities in the anhydrobiotic stage that could not be observed either by conventional light or electron microscopy. Our advance opens a door to quantitatively assessing fine differences in material properties and structure necessary to fully understanding an organism on the verge of life and death.

scholarly journals Improved chromatic and sensory characteristics of Plavac Mali wines – efficiency of maceration enzymes

2017 ◽  
Vol 35 (No. 3) ◽  
pp. 236-245 ◽  
Author(s):  
IVANA ALPEZA ◽  
KARIN KOVAČEVIĆ GANIĆ ◽  
ANDREJA VANZO ◽  
STANKA HERJAVEC
Keyword(s):  
Sensory Quality ◽  
Yeast Cells ◽  
Enzyme Preparations ◽  
Pectolytic Enzymes ◽  
Colour Parameters ◽  
The Moment ◽  
Red Grape ◽  
Different Characteristics ◽  
Physical And Chemical ◽  
Better Than

Two commercial enzyme preparations were used in the production of wine from the Croatian autochthonous red grape variety Plavac Mali in order to improve the extraction of polyphenolic components from grapes, chromatic parameters, and sensory quality. During two vintages, the conventional maceration without enzymes was compared with the maceration using products with different characteristics: pectinase with additional cellulase and hemicellulase activity and pectinase with inactive yeast cells. Both products affected polyphenolic extraction and colour parameters: intensity and hue, and ratio between the yellow, red, and blue colour in young wines (2 months after fermentation) and at the moment of bottling (9 months after fermentation). The correlation between anthocyanins and colour intensity was very strong. The expected reduction of quantitative chromatic parameters during aging was confirmed. Significantly better results were observed in wines produced with pectinase, in relation to all analysed physical and chemical parameters. The sensory analysis showed that wines produced with pure pectolytic enzymes were significantly better than those produced without the enzymes. A product of the combination of pectolytic enzymes and inactive yeast cells had a partial influence on the improvement of the phenolic and sensory quality. The overall quality was significantly more expressed in wines produced with pectolytic enzymes, especially in young wines.

scholarly journals Study of the Incorporation of Biomass Bottom Ash as a Filler for Discontinuous Grading Bituminous Mixtures with Bitumen Emulsion

2021 ◽  
Vol 11 (8) ◽  
pp. 3334
Author(s):  
Jorge Suárez-Macías ◽  
Juan María Terrones-Saeta ◽  
Francisco Javier Iglesias-Godino ◽  
Francisco Antonio Corpas-Iglesias
Keyword(s):  
Raw Materials ◽  
Bottom Ash ◽  
Chemical Properties ◽  
Physical And Mechanical Properties ◽  
Waste Biomass ◽  
Bituminous Mixtures ◽  
Bitumen Emulsion ◽  
Main Disadvantage ◽  
Physical And Chemical ◽  
And Chemical Properties

Energy consumption, because of population development, is progressively increasing. For this reason, new sources of energy are being developed, such as that produced from the combustion of biomass. However, this type of renewable energy has one main disadvantage, the production of waste. Biomass bottom ash is a residue of this industry that currently has not much use. For this reason, this research evaluates its use as a filler in bituminous mixtures, since this sector also has a significant impact on the environment, as it requires large quantities of raw materials. With this objective, first, the physical and chemical properties of biomass bottom ashes were evaluated, verifying their characteristics for their use as filler. Subsequently, bituminous mixtures were conformed with biomass bottom ash as filler, and their physical and mechanical properties were analyzed through particle loss and Marshall tests. The results of these tests were compared with those obtained with the same type of mixture but with conventional and ophite aggregates. This study confirmed that biomass bottom ash was viable for use as a filler, creating mixtures with a higher percentage of bitumen, better mechanical behavior, and similar physical properties. In short, more sustainable material for roads was obtained with waste currently condemned to landfill.

Total-shear grating based optical diffraction tomography

2021 ◽  
Author(s):  
Piotr Zdańkowski ◽  
Julianna Winnik ◽  
Paweł Gocłowski ◽  
Maciej Trusiak
Keyword(s):  
Optical Diffraction ◽  
Diffraction Tomography ◽  
Optical Diffraction Tomography ◽  
Total Shear

scholarly journals THE INFLUENCE OF YEAST RACES ON THE AROMA-FORMING SUBSTANCES OF TABLE WINES

2021 ◽  
Vol 447 (3) ◽  
pp. 13-18
Author(s):  
Z.А. Anarbekova ◽  
G.I. Baigazieva
Keyword(s):  
Direct Contact ◽  
Fermentation Process ◽  
Alcoholic Fermentation ◽  
Grape Juice ◽  
Yeast Cells ◽  
Higher Alcohols ◽  
Long Time ◽  
Speed Up ◽  
Biotechnological Processes

Wine is a product of biochemical transformations, compounds present in grape juice, by controlled alcoholic fermentation, that is, effervescence. Grape and yeast enzymes play a key role in the processing of grapes and the preparation of wine, influencing all biotechnological processes of winemaking. Adding liquid or dry active yeast to the wort allows better control of the fermentation process. Under the influence of these yeasts, sugar is converted mainly into alcohol or carbon dioxide, but the yeast itself during fermentation produces many molecules (higher alcohols, esters) that affect the aroma and taste of wine. These transformations take about two weeks and lead to a significant increase in temperature, which must be regulated, not allowing it to rise above 18-20°C: otherwise, some of the aromatic substances may evaporate and the fermentation process itself will stop. The amount of yeast that determines the correct and complete fermentation depends both on the quality of the wort itself, and on the more or less prolonged access of air, the ambient temperature. The air, or rather the oxygen of the air, has a beneficial effect on fermentation as long as there are still many nutrients (sugars) in the wort; as the latter are consumed, extremely small yeast cells are formed, which persist for a long time in the form of turbidity. The rapid course of fermentation can be greatly facilitated by the periodic stirring of yeast, which, settling to the bottom, lose direct contact with nutrients — the lower layers almost do not function. You can mix the wort mechanically or by adding healthy whole grapes to it; in this case, the wort is constantly and automatically mixed: the berries, rising up in the fermenting liquid, carry the yeast with them. In order to speed up the fermentation, the wort is sometimes ventilated, that is, air is introduced into it, by mixing. This article shows the influence of the yeast race on the fermentation dynamics of white grape must, the composition of organic acids and aroma-forming components. The races that ensure the production of highquality wine materials are identified.

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