2021-09-06

The mystery of the genetic evolution of the sea dragon is revealed

By yqqlm yqqlm

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The mystery of the genetic evolution of the sea dragon is revealed

Sea dragon, seahorse and anglerfish belong to the Syngnathidae family. Their names refer to the dragon shape of their bodies and the spectacular colors of their special leaf-like skin appendages. They are considered experts in camouflage because of their ability to mimic the appearance of seaweed. Like other members of the Syngnathidae family, sea dragons exhibit special adaptability and behavior. They have a tubular toothless mouth and lack the pelvic and pelvic fins and scales typical of fish. Instead, they have a bony shell covering the entire body.

Dried seahorses are usually used in traditional medicine. They do not swim horizontally like general aquatic animals, but slide slowly on coral reefs and shallow coastal waters, almost vertically-like a horse-head The part is bent downward. Their stalkless tail can be used to hold things tightly. Like other seahorse species, the males of sea dragons are responsible for protecting the bright pink eggs attached to their bodies until they hatch.

Researchers from five teams in China, Singapore, Japan, and Germany, while performing genome sequencing and studying the genetic basis of other external characteristics of sea dragons, focused their work on sea dragons’ sex determination, Toothless and newly evolved skin appendages. The research team led by Professor Lin Qiang of the Chinese Academy of Sciences in Guangzhou showed that a series of genes are responsible for this evolutionary development, and these genes usually control the development of fins. Therefore, the leaf-like skin appendages of sea dragons are fins with varying heights.

The mystery of the genetic evolution of the sea dragon is revealed(1)

Like a seahorse, there is no sea dragon Dental. They use their long noses to suck their food, namely small crustaceans, and swallow them whole. Genomic analysis revealed that among the relatives of the hippocampus, several genes that contribute to the development of teeth in other fish and humans are also missing. The research team tested the corresponding hypothesis by turning off the scpp5 gene in zebrafish, which is a well-studied model organism with pharyngeal teeth. As expected, the mutant fish showed reduced teeth. Therefore, the function of the gene responsible for tooth loss was proved in the molecular biology CRISPR-Cas experiment.

It is also typical that the male members of the hippocampus family take care of the fertilized eggs until they hatch. The seahorse males have developed brood pouches, but the old sea dragon males still place sticky eggs visibly on their tails. The female lays her eggs on this special location on the male’s body, and then is carried by the male sea dragon to run around to protect them from predation. Generally speaking, it is more common for male fish to take care of fertilized eggs than female fish, although this particular form has only evolved among members of the hippocampus family.

In this case, the researchers looked for sex determination mechanisms previously unknown in sea dragons. In general, it is difficult to locate sex determination in fish, because in most cases, they do not have special sex chromosomes, such as the X and Y chromosomes of mammals. The research team found that the molecular basis of the sex determination of sea dragons is in Muller’s hormones, just as it was previously recorded in the hippocampus.