Many animal species die after breeding. But octopuses are even worse. After laying eggs, the female
The short and dark life of octopusesintrigued scientists. In 1944, researchers hypothesized that mating was somehow pushing a molecular "self-destruct" button inside the sea creatures.
Almost 80 years have passed, but this idea is finally taking shape. Recently, scientists have found that mating appears to alter several important biochemical pathways in female octopuses.
The unusual behavior has been linked to changes incholesterol metabolism in the optic glands. On its basis, more 7-dehydrocholesterol is formed, as well as some steroid hormones and bile acids. They affect the fact that the females take more active care of the offspring, but at the same time they force the octopus to harm itself.
During the study, scientists extracted visualglands of adult female octopuses and studied them. It turned out that they produce two main types of signaling molecules: neuropeptides and steroid hormones. The problem is that after mating, the activity of those genes that are responsible for encoding neuropeptides is noticeably reduced. In turn, the genes that encode the enzymes involved in the synthesis of steroid hormones are much more strongly expressed. Cholesterol-7-desaturase just refers to such enzymes. It converts cholesterol to 7-dehydrocholesterol, which controls maturation and lifespan in many invertebrates.
Remarkably, in humans, a mutation that causeselevated levels of 7-dehydrocholesterol cause Smith-Lemli-Opitz syndrome. Recall that this is an autosomal recessive disease associated with metabolic disorders. The biochemical basis of this disease is a violation of cholesterol synthesis caused by insufficient activity or absence of the enzyme 7-dehydrocholesterol reductase. People with this mutation often injure themselves, and this is very similar to the behavior of the female octopus, which has puzzled scientists.
Through further research, researchersfound that after mating in the visual glands of female octopuses, the metabolism of cholesterol and its components, for example, 7-dehydrocholesterol, changes dramatically. Most likely, its high levels are inherently toxic not only to humans, but also to octopuses. Perhaps they lead to the development of signaling factors that kill mollusks, triggering the mode
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