A new discovery with tacoogenom may have the oldest chromosomes of all animals.
That’s a big deal, given the fact that these strange creatures did not even know if they had the gender form written on their genes.
Finally, the researchers of the University of Oregon seem to have solved the mystery.
Their peer -reviewed research trains the origin of sex chromosomes more than 480 million years ago and provides the first evidence of a genetic determination of the head and feet.
In order to judge whether the octopus is a male or a woman, biologists had previously rely on observations and distinguished individuals to lay eggs that produce sperm.
Searching for tacoogenom did not show any clear signs of the sex chromosome system. Scientists have begun to think that their head and feet are probably like some fish and reptiles. Gender was determined through environmental factors such as temperature where eggs are held, rather than inheritance of different chromosomes.
Examine the genes of two spot octopus in California (OCTOPUS BIMACULOIDES) – The first head and legs that decided the whole genomic sequence -The researchers have finally found a unique chromosome pair.
They discovered it with chromosomal number 17, which was only outstanding when the female octopasgenom was compared with the female octopasgenom. The female octopus seemed to lack one of the two copies.
“This specific chromosome has half of the sequence data and only one copy.” say Gabrielle Coffing, a doctoral program in biology and the first author of a new research.
“When we explored more, we came to the conclusion that we must have stumbled on the sex chromosome.”
We humans depend on the XY system, and two X -chromosome creates a default female body plan, but the presence of Y chromosome generally causes the development of male characteristics.
The octopus has the opposite system. Usually, it is a man who has a Double-Z pair and a woman with only one Z chromosome.
To confirm that this system exists in other heads, researchers compare three octopus, three squid species, and the Nautilus genome.
They Conclusion The head foot Z chromosome shall be “genome out of genome” with “single ancient origin”.
Two squid genomes And general octopus in East Asia (OCTOPUS SINENSIS) Although there was a signature of the same outdated value, it suggests that these creatures are from different systems, so that the Z chromosome occurs before splitting.
After further investigations, coffee and team discovered evidence of the chamber’s Nautilus chromosome ().Nautilus Pompilius) N. Pompirius Separated from the octopus 520 to 398 million years ago, Recent research This split was placed about 482 million years ago.
Therefore, the researcher of the University of Oregon Claim Z chromosome, “At least this had to have occurred so far.”
This means that octopus can have the oldest animal chromosomal that has been discovered so far, and even some insects be BE. thought Have a sex chromosome dating back 450 million years ago.
However, compared to the octopus, these ovary animal chromosomes are inadequate in the whole species.
For comparison The oldest accepted vertebrate chromosome It is a fish of a butterfly, and is considered to be about 180 million years ago. The female chin shark fish has a ZW sex chromosome set pair, contrasted with the female octopus “HEMIZYGOUS” Z chromosome.
ZW sex determination system It is found in birds, crustaceans, and some insects.
The octopus corresponding W chromosome may have been lost over time in the same way as the unfortunate trajectory of the human Y chromosome.
The story behind sex chromosome has changed significantly in recent years. Once, they were It is thought to be A unique feature of animal sex determination. However, biological research tends to be biased toward mammals.
After all, there are no sex chromosomes in fish or reptile, such as crocodile. Instead, the gender of their descendants is determined by other external factors through epigenetic regulations.
Obviously, there are still a lot of things to learn how sex chromosome has evolved and why. The octopus can be an attractive model of future research with their deep evolutional roots.
“Heads are already very interesting creatures, especially in neuroscience.” say。
“This only indicates another interesting thing about them. They really have an ancient sex chromosome.”
This study is published Current biology。
The earlier version of this article was released in March 2024 before the survey was reviewed.
