New discovery about the evolution of life

Humans may not have existed on Earth without the combination of two prokaryotes - small life forms without cell nuclei. UCLA molecular biologist James A. Lake published important new knowledge about prokaryotes and the evolution of life in the August 20 issue of Nature.

Internal symbiosis is the case of a cell living inside another cell. If two cells live together long enough, they will swap genes; they work together but often keep cell membranes and monkeys even their own genomes.

Lake discovered the first prokaryotes internal symbiosis. All other known endosymbiotic organisms have the participation of an eukaryote - a nucleus cell. Eukaryotes are found in all multicellular life forms including humans, animals and plants.

Lake, an honorary professor of molecular, cell and developmental biology and human genetics, said: 'This relationship has led to a completely different life form on Earth. We thought we needed eukaryote to do that, but we were wrong. '

In the Nature paper, Lake reports that two groups of prokaryotes - actinobacteria and clostridia - have teamed up to produce 'double-membrane' prokaryotes.

Lake said: 'A more advanced life form may not exist without this event. These are very important creatures. At the time these two prokaryotes evolved, there was no oxygen in the Earth's atmosphere. People cannot live, and no oxygen breathing creatures can live. '

Oxygen on Earth is the result of a subgroup of these two membrane prokaryotes. This subgroup, cyanobacteria, used the Sun's energy to produce oxygen through photosynthesis. They reproduce very quickly, pushing oxygen into the atmosphere; We cannot breathe without them. In addition, the combination of double-membrane prokaryotes has provided mitochondria in all human cells.

Electron micrograph of an actinobacteria species: Actinomyces israelii. (Photos: Wikipedia)

'This study is a new step in understanding how a group of animals have learned how to use solar energy and create the largest environmental change ever on Earth, and in school. This combination leaves very beneficial results, "said Carl Pilcher. He is the director of NASA's Space Biology Institute, based at NASA's Ames Research Center at Moffett Field, Calif, which co-sponsors research with the National Science Foundation.

"In addition to these two-membrane prokaryotes - which can use sunlight," Lake said, 'they have collected this abundant energy source. They have more genetic diversity than any other prokaryotes. Any other '.

He said: 'We have a gene flow from two different organisms, clostridia and actinobacteria. Because the group that owns the gene has two membranes, we hypothesize that internal symbiosis leads to two membranes. It seems that a single-membrane creature has 'swallowed' another creature. Their genome tells us that two-membrane prokaryotes combine genetic sequences from two different organisms'.

In this study, Lake looked back over 2.5 billion years ago. He performed genetic analysis of five prokaryotes groups.

Lake was very interested and interested in understanding the relationship between organisms.

He explained : 'We are all very interested in our ancestors. A friend of mine at UC Berkerley, Alan Wilson, was the first person to collect DNA from a large number of people around the world. He pointed out that we all have a kinship with a woman who lived in Africa 200,000 years ago. Some people in the mass media called her Eve, and he called her the lucky mother, the mother of all of us. '

'In this area, we have a large amount of data but cannot understand it. Internal fertility allows us to begin to clarify things; It tells us a lot of genes have been exchanged '.

'We missed the importance of collaboration. combined. If two prokaryotes come together, they can change the world. They restructured the Earth's atmosphere. That's a message of evolution for us: Collaboration, combining is the way forward. '

Actinobacteria have an unusual amount of DNA, with very high levels of necleotite 'G' and 'C' - chemicals that contain the data needed for protein formation. Nucleotite is based on the letters G (guanine), C (cytosine), A (adenine) and T (thymine); nucleotide chains act like chemical coding.

Some actinobacteria are pathogens, including tuberculosis and leprosy. Some clostridia can photosynthesize, something that no single membrane prokaryote can do. Photosynthesis may have been developed first in clostridia.

Two-membrane prokaryotes include pathogens that cause ulcers, and organisms that lead to the formation of chloroplasts in all green plants and are a precursor to plant growth.