The platypus gene reveals the evolutionary secret of mammals

Researchers claim they have decoded and analyzed the platypus genome - the furthest relatives of humans in the mammalian system.

The work has just appeared in Nature, opening a new door for scientists to study the genetic structure of this earliest mammal.

According to Jennifer Graves, National University of Australia, Canberra, co-project leader, the 'Platypus gene, similar to itself, is a surprising combination of reptilian and animal characteristics. breast.'

Platypus.(Photo: www.orgsites.com )

Analysis confirmed that platypus is the earliest animal in the mammalian genealogy .

The group of monogamous animals - including platypus and the closely related species of porcupine - are thought to be separated from other mammals at least 166 million years ago.

This very early separation means that the platypus gene carries information from the evolutionary timeline from the reptile to mammals, according to project director Wesley Warren, Washington University in St. Louis. Louis, Missouri.

'Platypus is of great importance in helping us understand which genes appear in ancestral reptiles and how mammals evolve their special traits.'

Eggs and milk

Platypus, an aquatic animal that lives in Western Australia, has long been puzzling for biologists.

Although classified into mammals, they retain primitive characteristics - including spawning - thought to be from mammals similar to mammals that lived more than 300 million years ago.

In this new work, scientists compare the platypus's genetic structure with other fully sequenced genes, including chickens, mice and humans. The main purpose is to identify which platypus traits are inherited from the ancient reptile ancestors and which characteristics evolved independently in the monogamous animal line.

As scientists predicted, platypus DNA was discovered to include some genes not found in other mammals. For example, the researchers identified the genes of egg yolk protein only with reptiles and fish.

According to Matt Phillips, a scientist from the Australian National University, not participating in this genetic project, 'New genetic data show that the egg laying characteristics of platypus are actually primitive features of reptile ancestors. '

However, the genome of mammals responsible for milk production is also detected in the platypus genome. While milk production and childbirth seem to go together, the platypus gene shows two common characteristics of mammalian species evolving at different times during the evolutionary period.

'The presence of complete milk-producing genes confirms that lactation evolved at least 166 million years ago, before the birth of a child.'

The picture illustrates the characteristics that platypus share with reptiles, birds and mammals.Scientists have deciphered platypus genes - the most distant relatives of humans in mammals - and revealed the evolutionary traces of mammals separated from reptiles hundreds of times ago. million years.(Photo: NFS / Nature)

Strange surprises

Genetic analysis also revealed new information about the basic biology of platypus and the origin of some of their unusual features.

A big surprise is the discovery of some specialized genes related to the ability to detect smells. This work shows that, in addition to the electric receptor in the mine, platypus also relies on chemical characteristics when locating and identifying aquatic prey.

The scientists also identified a set of genes involved in the production of platypus venom. Male platypus produces a painful snake-like venom, consisting of at least 19 different substances, which are inserted into the enemy's body or opponent through spurs on the hind legs of the male.

Previous studies found that producing toxins was the result of evolutionary change for genes that had other roles. Some similar genes appear to be mutated in platypus, but follow a process completely separate from the evolution of poison in solids.

Elliott Marguies, a scientist at the National Human Genome Research Institute in Bethesda, Maryland, said the importance of platypus genes beyond the field of early animal evolution.'For human genes, we are always trying to find the genes that play an important role, but it is a very difficult and exhausting process.'

He said comparing human genes and platypus would help researchers locate functional DNA sequences more easily.'Because platypus has evolved independently for a long time, any genetic sequence they have with humans is probably important.'