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X-Nuclei MRI and Energy Metabolism
Published in Guillaume Madelin, X-Nuclei Magnetic Resonance Imaging, 2022
Active transport. Active transport is defined as the movement of a solute across a membrane from the side of low electrochemical potential to the side with high electrochemical potential. The solute moves against its electrochemical gradient, which requires an outside source of energy. Active transport can be classified in two main categories: Primary active transport: This kind of transport needs ATP hydrolysis as a source of energy to transport ions or other solutes against their electrochemical gradient. Different types of proteins or enzymes (called ATPases) are responsible for primary active transport: P-type ATPase: Na+/K+-ATPase (sodium potassium pump), Ca2+-ATPase (calcium pump), H+-ATP (proton pump)F-ATPase: Mitochondrial ATPase, chloroplast ATPaseV-ATPase: Vacuolar ATPaseABC (ATP binding cassette) transporter: MDR, CFTR, etc.Secondary active transport: The electrochemical gradients set up by primary active transport store energy, which can be released as some ions move back down their gradients by facilitated diffusion. Secondary active transport uses this energy stored in these gradients to move other substances against their own gradients. The movement of some solutes down their electrochemical gradient across the membrane by facilitated diffusion is thus coupled with the active transport of other solutes against their electrochemical gradient. Two types of integral membrane proteins called cotransporters are responsible for secondary active transport: Symporters: A symporter allows two or more different kinds of solutes to cross the membrane in the same direction. Examples of symporters are: Na+/K+/2Cl–- symporter (NKCC), which uses the Na+ electrochemical gradient to import one K+ and 2 Cl– inside the cell; Na+/glucose cotransporter (SGLT); Cl–/K+ symporter; Na+/HCO3 cotransporter.Antiporters, or exchangers: An antiport or exchanger allows two or more different kinds of solutes to cross the membrane in one direction while others go in the other direction. Examples of exchangers are Na+/Ca2+ exchanger (which is reversible); Na+/H+ antiporter; Cl-/HCO-3 exchanger.
A review of quorum sensing regulating heavy metal resistance in anammox process: Relations, mechanisms and prospects
Published in Critical Reviews in Environmental Science and Technology, 2023
Caiyan Qu, Fan Feng, Jia Tang, Xi Tang, Di Wu, Ruiyang Xiao, Xiaobo Min, Chong-Jian Tang
Heavy metal resistance genes (HMRGs) play a crucial role in bacterial resistance to heavy metals, as they encode heavy metal-sensitive transcriptional regulators, binding proteins, efflux pumps, and detoxification enzymes (Jung et al., 2016). For instance, the copA gene encodes a Cu(I)-translocating P-type ATPase that is closely associated with Cu resistance, while the czcA gene encodes a heavy metal efflux pump that increases resistance to Co, Zn, and Ca (Rensing & Grass, 2003). In response to heavy metal stress, the abundance of HMRGs in anammox bacteria is significantly increased to enhance their resistance to heavy metals. Previous studies revealed that anammox bacteria increased the transcription of efflux genes encoding for the resistance nodulation cell division (RND) family, cation diffusion facilitators (CDF family) and P-type ATPase to export Zn(II), and upregulated cysteine synthesis genes to chelate Zn(II) (Ma et al., 2020). Genes involved in heavy metal homeostasis, mercuric resistance and chromate efflux were more abundant in the Cr and Hg contaminant sediment, which worked for Cr and Hg detoxification (Hemme et al., 2010; Yin et al., 2015b). Further, QS as a gene-to-phenotype regulation strategy was reported to involve the expression of HMRGs. Under Cu stress, AHL signal was recognized by the LasR regulator and directly binds to the cueR homolog to trigger the expression of Cu efflux gene (Thaden et al., 2010). Therefore, QS system is potential to regulate the HMRGs expression of anammox bacteria and symbiotic bacteria to enhance resistance to heavy metals.
Copper induces a downregulation of the Multidrug resistance protein 4 (MRP4) and Copper-transporting ATPase-RAN1 (RAN1) genes in red pine (Pinus resinosa) at low concentrations
Published in Chemistry and Ecology, 2023
Abagail Warren, Paul Michael, Kabwe Nkongolo
Copper transporting ATPase RAN1 (HMA7) is a membrane P-type ATPase that transports copper ions to ethylene receptors into the endoplasmic reticulum that are vital for the ethylene secretory pathway [23,24,40,41]. Copper acts as a cofactor of ethylene receptors, and for signalling transduction [23,24,41]; which is induced by RAN1. This transporter is also imperative for copper homeostasis in plants [12,25]. In this study, the RAN1 expression was downregulated in genotypes treated with the low concentration of 13 m/kg of copper sulfate, while the two higher concentrations of 130 and 1300 mg/kg did not induce differential expression when compared to water. This differs from the response of Quercus rubra as in this species RAN1 was downregulated under 656 and 1312 mg/kg copper sulfate treatment [8]. Arabidopsis thaliana shoots also showed supressed RAN1 activity after a treatment with 50 uM of copper sulfate [26]. Kobayashi et al. [12] reported that RAN1 is located in a region of high epistatic interactions indicating there may be other genes that influence RAN1 activity under copper stress.
Effect of Bacillus spp. strains on wheat nutrient assimilation and bioformulation by new spray drying approach using natural phosphate powder
Published in Drying Technology, 2022
Salah Eddine Azaroual, Najib El Mernissi, Youssef Zeroual, Brahim Bouizgarne, Issam Meftah Kadmiri
Much more pronounced effects on nutrient assimilation were observed in case of treatments receiving natural phosphate (PN), particularly wheat plants inoculated with bacilli strains isolated from rhizosphere samples. Interestingly, high amount of nutrients (NPK) in the root part of the plants was found in Natural Phosphate (PN) and P free control treatments (Figure 2). In contrary, higher NPK amounts were found in shoot part of the plants inoculated with the rhizosphere strains (Figure 2). According to our previous study,[4] the production of organic acids and inoculation with Bacillus spp. strains of the rhizosphere, affected significantly P content in plants in comparison with rock phosphate strains and un-inoculated treatments. In this assay, the change in the rhizosphere pH induced by rhizosphere bacilli strains can be considered as one of the hypothesis explaining nutrient assimilation by plant in contrary to plant accumulation of nutrients in the root observed in control treatments. Plant uptake of NPK nutrient by root in rhizosphere zone carry out through the membrane coupled to the transport of protons H+ (P-type ATPase). Also, the transport of nutrient from root to shoot is mediated by high affinity to H+-ATPase detected on root cells as well as in xylem and phloem cells.[31–35]