Amazoniac
Member
According to them, carotenoids are more prone to oxidation under low oxygen tension, but most food sources also provide some vitamin E. It must require to be present in significant amounts so that it's sacrificed while sparing carotenoids, which in turn can proceed to be converted without disturbance.
Yes, that appears to be the case. Worth reading:
[29a] Thyroxine and hypervitaminosis-A
Since we is on the topic of aldehyds, you also mentioned Alberto and Trabis' beloved methylglyoxal, which happens to be involved in diabetic damage once it's out of control (search for it in case it interests you); the following is related..
If we put aside all functions of poison A that involve the differentiation of cells, remodeling of tissues, formation of eye structures, and so on; we can focus on its direct involvement in vision:
- Vitamin A and Vision
- Metabolism of Carotenoids and Retinoids Related to Vision
- Grant Genereux's Theory Of Vitamin A Toxicity
- Retina, Retinol, Retinal and the Natural History of Vitamin A as a Light Sensor
"Broadened biological activity of vitamin A is a double-edged sword that also leads to broader toxicity caused by excessive vitamin A or its derivatives (Table 4). Retinoid toxicity can be caused by physical properties of retinoid (e.g., acting like a detergent at sufficient concentrations), chemical reactivity of retinoid (e.g., modification of random proteins by free retinal), or inappropriate biological activities (e.g., retinoic acid activating or suppressing gene expression at the wrong cell type or at the wrong time) (Table 4)."
"Retinal is the vitamin A derivative that is most toxic, due to its chemical reactivity."
"Retinal is the vitamin A derivative that is most toxic, due to its chemical reactivity."
The retina is in question and it consists of layers at the back of the eye. The known cone cells there are functional during daytime in bright light conditions, whereas the rod cells are relatively less sensitive, so they is more useful in dim lighting, allowing the guru to mostly sense shapes.
Both cells have their proteins (opsins) varying in structure to be sensitive to specific light spectrums, with cone cells having a group of opsins to allow them to interact with wavelengths respective to what we perceive as red, green, and blue spectrums (therefore forming colors). The poem is not in vain, it's because all these proteins are attached to poisonal, and their combination yields the familiar molecules required for vision: photopsins and rhodopsin.
When light strikes these molecules, it cleaves them with changes in conformation of poisonal from cis- to trans-poisonal. This signals the cerebra, and once you have multiple signals on different spots you start to form images. It's 11-cis-poisonal that is found attached to opsin through the protein's lysine residue. And this ties in with what has been posted previously on aldehydes being considered toxic due to their reactivity, being related to the carotenoid breakdown-products and all being prone to be quite harmful when they go awry.
In the first linked article they also claim that the "life time of all-trans-retinal is determined by the activity of RDH8 [117] and other dehydrogenases of the rod outer segment [44,70,108], which reduce the aldehyde to the alcohol (all-trans-retinol), a less chemically reactive species". It should be obvious that there is a good reason why poisonal is used for vision because it can be challenging to guard it, especially under brutal excitation.
They often refer to it as visual cycle to allude to the regenereuxion of the required form, but the process is more elaborate than it seems, it's detailed in the articles.
The point is that poison A is indispensable and irreplaceable for vision, it's at its fundamental core, and this simple aspect by itself invalidates all delusional speculations about its nature. Now get this (again):
Garrett Smith said:
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- Alterations in Vitamin A and E Levels in Liver and Testis of Wild Ungulates from a Lead Mining Area
- Beriberi, White Rice, and Vitamin B (978-0756763848)
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