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Cytokinins can also be produced by recycled tRNAs in plants and bacteria. [20] [21] tRNAs with anticodons that start with a uridine and carrying an already-prenylated adenosine adjacent to the anticodon release on degradation the adenosine as a cytokinin. [20] The prenylation of these adenines is carried out by tRNA-isopentenyltransferase. [21]
Macrophages within the atherosclerotic legion area have a decreased ability to migrate, which further promotes plaque formation as they are able to secrete cytokines, chemokines, reactive oxygen species (ROS) and growth factors that stimulate modified lipoprotein uptake and vascular smooth muscle cell (VSMC) proliferation.
The binding of bacterial molecules to receptors on the surface of a macrophage triggers it to engulf and destroy the bacteria through the generation of a "respiratory burst", causing the release of reactive oxygen species. Pathogens also stimulate the macrophage to produce chemokines, which summon other cells to the site of infection. [2]
However, macrophages, especially alveolar macrophages, usually produce far lower levels of ROS than neutrophils, and may require activation for their bactericidal properties. Instead, their transient oxidative burst regulates the inflammatory response by inducing cytokine synthesis for redox signalling, resulting in an influx of neutrophils and ...
Beyond increasing inflammation and stimulating the immune system, macrophages also play an important anti-inflammatory role and can decrease immune reactions through the release of cytokines. Macrophages that encourage inflammation are called M1 macrophages, whereas those that decrease inflammation and encourage tissue repair are called M2 ...
Some shade-loving plants (sciophytes) produce such low levels of oxygen during photosynthesis that they use all of it themselves instead of releasing it to the atmosphere. [12] Although there are some differences between oxygenic photosynthesis in plants, algae, and cyanobacteria, the overall process is quite similar in these organisms.
The activated NADPH oxidase generates superoxide which has roles in animal immune response and plant signalling. [9] Superoxide can be produced in phagosomes which have ingested bacteria and fungi, or it can be produced outside of the cell. [10] In macrophages, superoxide kills bacteria and fungi by mechanisms that are not yet fully understood.
In bacteria, the special pair is called P760, P840, P870, or P960. "P" here means pigment, and the number following it is the wavelength of light absorbed. Electrons in pigment molecules can exist at specific energy levels. Under normal circumstances, they are at the lowest possible energy level, the ground state.