Fungi and Water
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Fungi have cell walls similar to plants and are different from animals. The fungal cell wall is composed of chitin that gives shape, form, and rigidity to fungi. It protects against mechanical injury, prevents osmotic lysis, and provides passive protection against the ingress of potentially harmful macromolecules (2–3). Chitin is a polymer of N-acetyl-D-glucosamine. The major polysaccharides of the cell wall matrix consist of non-cellulosic glucans such as glycogen-like compounds, mannans (polymers of mannose), chitosan (polymers of glucosamine), and galactans (polymers of galactose). Small amounts of fucose, rhamnose, xylose, and uronic acids may be present (2). Glucan refers to a large group of D-glucose polymers having glycosidic bonds. Insoluble β-glucans are apparently amorphous in the cell wall. Yeast cell wall is composed of three layers and is about 200- to 600-nm thick. Its inner surface is chitinous, and its outer layer contains α-glucan (2). In addition to chitin, glucan, and mannan, cell walls may contain lipid, protein, chitosan, acid phosphatase, α-amylase, protease, melanin, and inorganic ions such as phosphorus, calcium, and magnesium (2). The fungal wall also protects cells against mechanical injury and blocks the ingress of toxic macromolecules. The fungal cell wall is also essential to prevent osmotic lysis. Even a small lesion in the cell wall can result in extrusion of cytoplasm due to the internal (turgor) pressure of the protoplast. The cell membrane of a fungus has a unique sterol and ergosterol (3).
Effect of Elevated CO2 Conditions on Medicinal Plants
Azamal Husen in Environmental Pollution and Medicinal Plants, 2022
Elevation in photosynthetic activity in plants is potentially related to rising inactivity of RuBisCO (ribulose 1,5-bisphosphate carboxylase enzyme) which can alter growth as well as production of secondary metabolites (Portis et al. 2007). Under higher carbon dioxide conditions, there is an increment in the rate at which carbon is subsumed into carbohydrates; this continues as RuBisCO becomes one of the limiting factors. The higher CO2 levels result in rapid leaf area development, which further increases the surface for transpiration and an enhanced rate of transpiration (Betts et al. 2007). There is an abrupt increase in stomatal conductance which causes the rapid opening of stomatal guard cells under e[CO2] in the atmosphere. There is also a significant improvement in the water-use efficiency of plants through increased turgor pressure which is important in the growth and development process.
Histomorphometry
C M Langton, C F Njeh in The Physical Measurement of Bone, 2016
In accomplishing this impressive technical achievement, Odgaard et al [111, 112] removed the marrow tissue before commencement to gain better image quality. This tacitly assumes that the trabecular network is entirely integrated, as is probably the case in young healthy material where the number of bone particles is 1. The same may not apply to unhealthy material where part of the network may be detached from the main framework. No matter how efficient the automation, or how fine the final product, there remains a fundamental error in extracting the marrow tissue from the spongiosa for the sake of image enhancement without first ensuring that isolated trabeculae and possibly larger trabecular profiles are not removed at the same time. The unanswered question is not whether isolated fragments of the cancellous network are lost, for the evidence indicates that they will be [60, 113, 114], but how much is lost in this way. For example, if the result from a video reconstruction of the block surface of a large ilial autopsy specimen from a normal 80-year-old man is typical and representative, it indicated by extrapolation the presence within his skeleton of not only 80 000 real trabecular termini but also 8000 real islands (M F Wilson and J E Aaron, unpublished data). Finally with respect to the marrow tissue itself, there also arises the possibility that it too contributes biomechanically. Like the growing plant shoot or root tip, it has turgor pressure which when biologically channelled can lift concrete paving stones.
Exosomes: from biology to immunotherapy in infectious diseases
Published in Infectious Diseases, 2023
Velia Verónica Rangel-Ramírez, Hilda Minerva González-Sánchez, César Lucio-García
In fungi, extracellular vesicles were discovered more than a decade ago in the pathogen Cryptococcus neoformans [337]. In contrast to mammalian cells and similarly to Gram-positive bacteria, these fungal-vesicles have to traverse a cell wall to be released, however, until now, many steps of this process are still unknown [338]. It has been suggested that vesicles would pass through channels for their release, that cell wall is remodelled by enzymes facilitating areas for extracellular vesicles transit, or that they are forced to pass through cell wall pores by turgor pressure [338,339]. Moreover, secretion in the Fungi is particular, since the majority of proteins lack the signal peptide [340], and different secretory mechanisms may be involved including the conventional route (ER-Golgi pathway), the ESCRT-mediated pathway and the one involving the Golgi reassembly stacking proteins (GRASP) [311].
The force-from-lipid principle and its origin, a ‘what is true for E. coli is true for the elephant’ refrain
Published in Journal of Neurogenetics, 2022
Boris Martinac, Ching Kung
MscL is half-activated by membrane tension of ∼12 mN/m and fully activated by close to lytic tension of a pure lipid bilayer (Sukharev, Sigurdson, Kung, & Sachs, 1999; Nomura et al., 2012). This makes MscL a MS channel requiring the highest membrane tension on the physiological spectrum ranging from 1 to 25 mN/m, which perfectly fits its role of a osmoregulatory emergency nanovalve opening upon extreme changes in turgor pressure during a hypoosmotic shock experienced by bacterial cells (Bialecka-Fornal, Lee, & Phillips, 2015; Levina, Totemeyer, Stokes, Louis, Jones & Booth, 1999). Being relatively simple in structure, MscL has been analyzed extensively on how it opens and closes. Essential in determining its open structure was the activation of MscL by lipid forces, including the insertion of the cone-shaped amphipath lysophosphoshatidylcholine (LPC) into a single leaflet of the lipid bilayer (Perozo, Cortes, et al., 2002). The change from closed to open structure in MscL entails an iris-like expansion resulting in a large pore of 28Å in diameter (Sukharev, Betanzos, Chiang, & Guy, 2001; Betanzos, Chiang, Guy, & Sukharev, 2002; Perozo, Cortes, et al., 2002; Wang et al., 2014). This expansion is driven by ‘pulling’ the N-terminal helix and tight protein–lipid interactions with TM2 (Bavi, Cortes, et al., 2016; Iscla, Wray, & Blount, 2008).
Bio-acoustic signaling; exploring the potential of sound as a mediator of low-dose radiation and stress responses in the environment
Published in International Journal of Radiation Biology, 2022
Bruno F. E. Matarèse, Jigar Lad, Colin Seymour, Paul N. Schofield, Carmel Mothersill
Drought stress and predation constitute two of the major physiological stressors of vascular plants. Under drought stress some plants produce measurable bio-acoustic emissions (De Roo et al. 2016). The mechanisms for generating these signals are not fully understood but may involve the effects of decreasing hydrostatic pressure in xylem, leading to the production of ultrasonic sound emissions variously measured as >20 kHz (Tyree and Dixon 1983) and from 10 to 300 kHz (Laschimke et al. 2006). With rapidly decreasing pressure in the xylem, collapse of bubbles caused by cavitation has been suggested as one mechanism for the generation of sound, but an alternative hypothesis derived to explain the ‘violent acoustic activity’ detected in Ulmus sp. in response to drought stress, is release of energy from the xylem-adherent bubble system that normally contributes to water flow (Laschimke et al. 2006; Zweifel and Zeugin 2008; Gagliano et al. 2012a, 2012b; Gagliano 2013). Respiration and metabolic growth activity of the cambium is another method suggested to be involved (Zweifel and Zeugin 2008). The cambium is the portion between the xylem and phloem where cells are rapidly dividing and is responsible for secondary growth of stems and roots (Zweifel and Zeugin 2008; Schöner et al. 2016). At nighttime when the plant is subject to drought stress, the cambium has increased turgor pressure due to increased respiration. This increased pressure causes greater levels of carbon dioxide to enter the xylem, resulting in more gas bubbles and subsequent acoustic emissions. In the absence of drought stress and consequent xylem cavitation, young corn roots are able to produce clicking sounds under water – the reason for retaining or developing this mechanism is unknown (Schöner et al. 2016). It is apparent that a variety of plant species have developed mechanisms for sound production.
Related Knowledge Centers
- Bacteria
- Cell Wall
- Lipid Bilayer
- Lysis
- Osmosis
- Semipermeable Membrane
- Vacuole
- Cell Membrane
- Solution
- Tonicity