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Heavy Metal Toxicity in Plants and Its Mitigation
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
As free-living and synergetic, PGPR can also directly improve plant growth by phosphorus solubilization for plant intake; nitrogen fixation; the absorption of micro elements such as iron by siderophores; the release of phytohormones as cytokinins, auxins, and gibberellins; and the decrease in ethylene production. PGPR can also improve plant growth by several indirect mechanisms such as antibiotic synthesis, exhaustion of iron by rhizospheres, induced systemic resistance, synthesis of cell wall–degrading enzymes, and the struggle for association with roots by quorum sensing (Glick et al., 2007; Daniels et al., 2004). Nitrogen-fixing bacteria chemically stimulate rhizobium nodule genes, Nod factors, and acyl homoserine lactone (AHL) production for phytoremediation. Dell’Amico et al. (2005) stated that in the presence of PGPR in relation to rhizoplane and rhizosphere, several populations of microbes are capable of tolerating large HM contaminants. Soil microbes are famous for enabling the mobility of metals in plants as well as oxidoreduction modification or with the synthesis of iron chelators and siderophores for confirming the presence of iron, and assembling the phosphates (Burd et al., 2000; Guan et al., 2001). Likewise, ethylenediaminetetraacetic acid (EDTA) and EGTA are also better chelators to stimulate the accessibility of metals in plants, while such chelators might cause negative impacts such as metal leakage and fewer microbes action (Römkens et al., 2002).
Endogenous Bioelectric Phenomena and Interfaces for Exogenous Effects
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
For regenerative therapy the fact is important, that in normal human mesenchymal stem cells (hMSCs), cell differentiation is accompanied by a progressive hyperpolarization. Artificial depolarization holds these cells in an undifferentiated (stem-like) state, while artificial hyperpolarization accelerates differentiation (77). An increasing Ca++ entry into the cell and a positive feedback loop between Ca++ entry and Ca++-dependent potassium channels is discussed as the next step after the changes in resting potential (78). In further signaling cascades till gene regulation, e.g. phosphatase and tensin homolog (PTEN) is involved as well as epigenetic regulators like histone decarboxylase (HDAC). Also Feng et al. (79) report that DC EF induces directional migration of neural precursor cells. Whole cell patching revealed that the cell membrane depolarized in the EF, and buffering of extracellular calcium via EGTA prevented cell migration. Immunocytochemical staining indicated that the same electric intensity could also enhance differentiation and increases the percentage of cell differentiation into neurons, but not astrocytes and oligodendrocytes. The results indicate that DC EF is capable of promoting cell directional migration and orchestrating functional differentiation, suggestively mediated by calcium influx during DC field exposure.
Microbial Biofilms and Biofilm Reactors
Published in Martin A. Hjortso, Joseph W. Roos, Cell Adhesion, 2018
Brent M. Peyton, William G. Characklis
Sloughing has been observed after substrate concentration decreases. Bott and Miller (43) observed a 50% decrease in biofilm weight in aluminum tubes at a liquid velocity of 0.5 m/s within 4 days after stopping the nutrient supply of 4 mg/L glucose. However, at a liquid velocity of 2.0 m/s, the decrease in biofilm weight was insignificant. These data indicate that the fluid conditions under which the biofilm was grown do have an effect on the sloughing properties. Sloughing has been induced (44) by adding ethylene glycol-bis(β-aminoethyl ether)-N,N-tetraacetic acid (EGTA), a calcium-specific chelant. The divalent calcium ions give tertiary structure to the polymer matrix and may play a major role in determining biofilm strength. Thus, removing calcium causes a partial collapse of the biofilm structure.
A generalized study of the distribution of buffer over calcium on a fractional dimension
Published in Applied Mathematics in Science and Engineering, 2023
Sanjay Bhatter, Kamlesh Jangid, Shyamsunder Kumawat, Sunil Dutt Purohit, Dumitru Baleanu, D. L. Suthar
In this paper, we have discussed four buffers (EGTA, Troponine, Calmodulin, BAPTA). BAPTA primarily protects cells against toxic calcium overload. EGTA is a chelating agent with a high affinity for calcium ions. EGTA is used as a buffer equal to the pH of the living cell. Calmodulin is a critical neuronal protein that is a crucial mediator of several -dependent intracellular signalling cascades in the brain. Calmodulin modulates synaptic transmission and synaptic plasticity through Ca, which relies on its target proteins in pre and postsynaptic compartments. Calmodulin is a regulatory protein used to detect changes in calcium ion concentration.