创新世界

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创新世界
This mechanism, known as physiological color change, relies on the movement of pigment-containing organelles (melanosomes in melanophores) within the cell’s cytoplasm. The cell itself does not change shape. Instead, a complex network of cytoskeletal tracks, primarily microtubules, guides the transport of these organelles. Motor proteins, such as dynein and kinesin, act as the engines for this transport. Hormonal signals, received by G-protein coupled receptors on the chromatophore’s surface, initiate a signaling cascade. For example, melanocyte-stimulating hormone (MSH) binding leads to an increase in intracellular cyclic AMP (cAMP). Elevated cAMP activates protein kinase A (PKA), which in turn phosphorylates motor proteins, leading to the dispersion of pigment granules from the cell center to the periphery, thus darkening the skin. Conversely, melanocyte-concentrating hormone (MCH) or melatonin binding leads to a decrease in cAMP, causing the motor proteins to reverse direction and aggregate the pigments in the center of the cell, lightening the skin. This entire process is reversible and allows the animal to adapt its coloration to the background, light levels, or social signals, albeit on a much slower timescale (minutes to hours) compared to the neuromuscular control in cephalopods.
激素对色素转运的调控
(如果日期未知或不相关,例如“流体力学”,则提供其显著出现的近似估计)
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