动物造模 z-bo 2022-02-04 424

　　As we all know, when a species needs to change to adapt to its specific needs, evolution can help a lot. But what if the same "group" has different needs?

　　If there are only quantitative differences between these small groups, the species is usually a new subspecies. However, in many cases, there are differences between men and women, which makes it almost impossible to form new species (unless all men in the population cannot be killed). For more information, see "Men Ruling the World Through Asexuality." This crayfish did it! )

　　Therefore, as a result of evolution, genes that are beneficial to women will fight against genes that are harmful to men (and vice versa), and eventually balance. Now, scientists have found this situation in fruit flies, but this time they have found a solution to this genetic war.

　　The Greek God in Drosophila

　　In this example, the place where the war broke out were two genes-Apollo and Artemis (two in Greek mythology from the names of the sun god and the moon goddess). It is the part that contains the genome. These two genes are not only adjacent to each other, but also have evolutionary homology. About 200,000 years ago, the genes of our ancestors were repeated, and these two genes were born. In fact, scientists have discovered several varieties of fruit flies that have no duplicate ancestral genes. These fruit flies contain only one gene of this type. The Apollo gene has important functions. If this situation is eliminated, the survival rate of men and women will be reduced to 1/3, and all surviving men will be sterile. The lethality of Artemis seems to be low, but after removal, all females become sterile. It can be concluded that these ancestral genes play an important role in reproduction of both sexes. Two genes are derived from the duplication of ancestral genes and correspond to males and females respectively. But, surprisingly, the presence of these two genes is harmful to the opposite sex. In the absence of Artemis (corresponding to female genes), fertility increased by 15%. When female Apollo (Apollo) mutation loses function, fertility increases by more than 20%. This suggests that when genes mutate to continuously adapt to the needs of men, they can also interfere with female reproduction, and vice versa.

　　Male and female reactions

　　How to solve this kind of damage? In Drosophila melanogaster (a standard laboratory fruit fly), we found that Apollo is much more active in male germ cells than in females. Similarly, Artemis has higher activity among women. However, it is not yet known how Drosophila variants containing only the single gene described above achieve this male-male balance. However, in other subspecies of Drosophila, some ancestral genes are even repeated three times according to sex. In these cases, the expression activities of the two genes of the two sexes are significantly different.

　　What is the role of these genes? Scientists measured DNA sequences and found that these sequences can translate proteins, form fibers in cells and form the cytoskeleton. In men, these fibers transcribed by Apollo play an important role in the final cell division of spermatogenesis. The eggs of women without Artemis are usually larger and sterile. These genes also have other important functions (remember, 1/3 of fruit flies die because of lack of this gene), people don't know yet. Although these two genes are highly homologous, they have important evolutionary differences. For example, the proteins translated by the two differ by tens of amino acids, and the two genes each have newly added or deleted fragments during the replication process. This major difference (not yet determined) may have appeared about 50,000 years ago.

　　We need to study many details about this gene, but the picture of evolution is already clear. It is expected that this mechanism will also work in other species. For example, in mammals, the birth of eggs and sperm are two completely different processes, requiring proteins of different sexes. Gene duplication is also very common in life regeneration. This result can be observed by comparing the genes of the child and the parent. We look forward to further research, which can open up a new chapter of genetic mystery.