[ad_1]
This is the main conclusion of a survey conducted by Vctor Borrell, of the Institute of Neuroscience of Alicante, in collaboration with research centers in Germany, Switzerland, the United States, United States and United States and published today in Cell.
More than 500 million years ago, in Cmbrico, the primitive animals that inhabited the oceans abandoned the aquatic environment and colonized the Earth's surface, giving birth to the first reptiles, amphibians and birds of the planet.
The new environment forced animals to adapt all their vital systems, their senses, their diet and their mode of locomotion, and all these changes had their epicenter in the brain, which evolved into a much larger organ and complex than ever.
But evolution of the brain was not even among the different species: in amphibians, birds and reptiles, the cerebral cortex was organized into three layers of neurons, while in mammals it was extended to six layers.
These differences in size and complexity mark different cognitive abilities in animals, from the simplest to the last link in the chain occupied by primates and humans.
But how was this qualitative leap in the brains of animal species? .
"The big change took place in the production of neurons," says Vctor Borrell in statements to Efe.
Until then, the brains of vertebrates (mainly reptiles) produce neurons from stem cells that divide "directly" but something has changed and the mammalian cerebral cortex has "indirect" neurognosis, This allowed them to make many more neurons and to have a much more complex cerebral cortex.
"We still do not know where exactly but in the evolution of mutations occurred in particular regions of the genome, the part that does not encode the proteins," until recently misnamed "junk DNA ", explains the researcher.
And does the human genome have a "coding" part which contains the information necessary for protein formation and the "non-coding" which gives instructions on the amount of each protein to be made.
"It's a part of the genome that is very little known but very important because it determines how, when, and where each protein is expressed, something essential in an organism," warns Borrell.
Research, carried out with mouse embryos, chickens, snakes and organoids of the human brain (cell cultures mimicking the structure and function of an organ), concludes that there is 300 million years ago some changes alter this part of the genome. They altered the amount of expression of two genes (Robo and DII1) directly involved in the generation of neurons.
"The part of the genome that regulated the levels of the two proteins changed and, with that, changed the information that marked how much of these proteins had to be made, and that's what gave birth to neurons from that moment on, indirectly, "says Borrell.
But not only that: the neurons born from this (indirect) process were a new type of neuron", with different characteristics that are what we see in layers 2, 3 and 4 of the mammalian cerebral cortex and that reptiles do not have, "he says.
The study points out that this qualitative leap in evolution occurred without the need for new proteins, but with those that all vertebrates already had: "Just change the amount for that the number of neurons and the size of the brain and its complexity can be very different, "concludes Borrell.
Source: EFE
Photo: Archivo AFP
[ad_2]
Source link
