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Molecular Biology of Thermophilic and Psychrophilic Archaea
Published in Ajar Nath Yadav, Ali Asghar Rastegari, Neelam Yadav, Microbiomes of Extreme Environments, 2021
Chaitali Ghosh, Jitendra Singh Rathore
The cell membrane is a major barrier of the cell, which separates the vital cytoplasm from the surrounding environment. The major component of the cell membrane is phospholipids, which is involved in a wide variety of cellular processes. They work like a matrix to support integral membrane proteins having diverse functions. Other important functions governed by lipid are protein translocation, signal transduction, DNA replication and cell division, transport and many other cellular mechanisms (Dowhan 1997; Cronan 1978). Phospholipids consist of hydrophobic hydrocarbon tails as well as a polar head. Interaction between hydrophobic tails makes a bi-layer structure. In such an orientation, the hydrophobic region is oriented towards the inside of the membrane, whereas the polar head is linked by the glycerolphosphate backbone to the hydrophobic tail, facing the external aqueous face. The bilayer structure of the membrane is embedded with membrane-integral proteins and is semi permeable in nature. Therefore they allow an exchange of limited cellular constituents, including nutrients and ions (Raetz and Dowhan 1990). Composition of membrane lipid represents a taxonomic signature, used to differentiate the various kingdoms of life.
The Role of Nanoparticles in Cancer Therapy through Apoptosis Induction
Published in Hala Gali-Muhtasib, Racha Chouaib, Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
Marveh Rahmati, Saeid Amanpour, Hadiseh Mohammadpour
Endoplasmic reticulum (ER) is an organelle implicated in the secretion and correct folding of proteins, Ca2+ balance, as well as maintaining the quality control of proteins and cell homeostasis. In different situations, such as physiological or pathological conditions, the demand for folding proteins is increased, resulting in an elevation of unfolded or misfolded protein levels in the ER lumen. This burden on the ER is known as the ER stress. To cope with the stress, the unfolded protein response (UPR) is activated. If the URR cannot restore the stress, the UPR mediates apoptosis [38]. The studies have shown that two main pathways, a transcription factor- and a caspase-dependent signaling pathway, mediate ER stress-dependent apoptosis. The UPR mediators, such as transcription factor GADD153/CHOP, can disrupt the balance between BCL-2 and BAX, resulting in the induction of apoptosis. ER stress-induced apoptosis also occurs through the activation of CASP-12, independent of mitochondrial and death receptors pathways (Fig. 3.1) [39]. There is contradictory information about ER stress-mediated apoptosis. Some have demonstrated that UPR mediates apoptosis through CASP-12, while some claimed that CASP-12 is not related to UPR-mediated apoptosis, rather it is dependent on the mitochondrial apoptotic pathway [40, 41]. Interestingly, in most humans, CASP12 appears to be nonfunctional [42], and the ER-resident of CASP-4 is known to be implicated in ER stress-induced apoptosis [43–45].
Contrast enhancement agents and radiopharmaceuticals
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The cell membrane represents a barrier to the passage of material into the cell. Movement of radiopharmaceuticals may occur passively by diffusion down an electrochemical gradient, e.g. in lipid-soluble transport. This is a slow process and some structures are impermeable to all but the most essential materials. The blood–brain barrier is a classic example of this. However, if it is disrupted by a pathological process, radiopharmaceuticals such as pertechnetate are able to pass into the area of damage. More rapid mechanisms of transport are mediated by specialised structural components in the cell membrane. Facilitated diffusion results in the rapid transfer of substances along the electrochemical gradient; active transport results in movement against a concentration gradient involving the use of adenosine triphosphate (ATP) as a source of energy. Figure 2.24a demonstrates an axial slice from a 99mTc-hexamethylpropyleneamine oxime (HMPAO) scan.
Computation of the mitochondrial age distribution along the axon length
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Ivan A. Kuznetsov, Andrey V. Kuznetsov
Mitochondria generate easily usable chemical energy for cells. In addition to their direct involvement in cellular respiration, they are also involved in apoptosis, calcium buffering, and many other important biological functions (Fan et al. 2001; Picard and McEwen 2018). Abnormalities in mitochondrial transport occur in many neurological disorders (Zheng et al. 2019). Recent research implicates α-synuclein-induced disruptions of mitochondrial trafficking in the development of Parkinson’s disease (PD) (Clague and Rochin 2016; Shahmoradian et al. 2019). Since packed mitochondria membrane fragments are one of the components found in Lewy bodies (Shahmoradian et al. 2019), investigating the transport of mitochondria is important for understanding the fundamentals of PD, for example, in regard to possible energy deficits in dopaminergic neurons due to disruptions in mitochondrial axonal transport (Prots et al. 2018).
Multiple inhibitory effects of succinic acid on Microcystis aeruginosa: morphology, metabolomics, and gene expression
Published in Environmental Technology, 2022
Yi-dong Chen, Chu Zhao, Xiao-yu Zhu, Yuan Zhu, Ru-nan Tian
The cell membrane is an important barrier for the exchange of substances and energy between the intracellular and extracellular environments. It can maintain the relative stability of the intracellular environment and play a vital role in cell growth, division, and differentiation [33]. The cell membrane is the target site of some allelochemicals. Many studies have reported that allelochemicals can change the structure of cell membranes, destroy membrane integrity, and increase membrane permeability [20, 34]. Damaged cell membranes not only adversely affect the structure and function of the cell organelles but can also lead to the efflux of cytoplasm, further accelerating lysis of the algal cell. This is one of the most important mechanisms by which allelochemicals inhibit the growth of algae [18, 30]. Apigenin and 5,4’-dihydroxyflavone compromised the membrane integrity and induced permeabilization in 30% and 44% of the M. aeruginosa cells, respectively [34]. As the N-Phenyl-1-naphthylamine exposure dose increased, the percentage of membrane-damages cells increased [35]. The increase of nucleic acid and protein in algae culture exposed to 60 mg L−1 SA indicated that the cell membrane of Microcystis was damaged and the membrane permeability increased. The efflux of intracellular nucleic acid and protein adversely affected the normal cell metabolism. As shown in Figure 2, cell membrane damage increased with increased exposure dose and exposure time. After exposure to 60 mg L−1 SA for 48 h, some algal cells were lysed, a result similar to that of Zhao et al [20].
The response of three typical freshwater algae to acute acid stress in water
Published in Journal of Environmental Science and Health, Part A, 2022
Xing Ma, Xuan Chen, Jiangtao Fan, Yunzhong Wang, Jianfeng Zhang
The cell membrane is the first barrier between the external environment and the intracellular medium and plays an important role in cellular growth, metabolism, energy transduction, and maintenance of a constant intracellular environment.[37] Moreover, the cell membrane regulates the movement of substances entering or exiting the cell and catalyzes exchange reactions.[38] Maintaining the integrity of the cell membrane is necessary for the normal growth of algal cells. Similar to the response of algae to salinity stress, the osmotic pressure inside and outside algal cells also increases with the concentration of hydrogen ions in the culture medium. As a result, the death of algae under acid stress could be attributed to the structural destruction of the cell membrane caused by excessive osmotic pressure and the attack of ROS induced by excess H ions entering the cell membrane. This observation was confirmed by the entry of PI dye into cells with damaged membranes and the staining of nucleic acid substances.