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It is as if the long neck of the giraffe is transferred to a duck - lateral transfer of genes

At the unicellular levels - bacteria and archaea ('ancient' bacteria) - transferring genes between completely different species is a routine matter, says Prof. Peter Gugraten from the University of Connecticut, who came to Israel on a Fulbright scholarship for joint research with Dr. Uri Gofna from Tel Aviv

Prof. Peter Gograten, photo: University of Connecticut photo by Daniel Buttrey
Prof. Peter Gograten, photo: University of Connecticut photo by Daniel Buttrey
The classic concept of genetics is that creatures pass from generation to generation what they inherited from their parents with one level of precision or another, and only this precision produces the variation necessary to adapt to the environment or to be eliminated by natural selection. This concept is wrong because it relies on the assumption that sexual reproduction or reproduction by division (mainly in less developed plants and animals) is nature's only way of passing genes from generation to generation. At the unicellular levels - bacteria and archaea ('ancient' bacteria) - transferring genes between completely different species is a routine matter.

Prof. Peter Gograten, director of the bioinformatics laboratory and professor of molecular biology at the University of Connecticut, recently completed a six-month sabbatical stay at the biology department at Tel Aviv University, as part of the prestigious Fulbright program, managed in Israel by the USA-Israel Education Foundation. Together with Dr. Uri Gofna from Tel Aviv University, he studied how new traits are transferred to archaea, which previously existed in archaea or bacteria that are genetically distant from them.
"Until the nineties, they tended to think that even if there were lateral transfers of genes here and there, they were at the beginning of the formation of life, but in principle the evolution of most bacteria and microorganisms in general is vertical - tree-like. Cells divide and evolution continues only through the accumulation of mutations. The concept changed a lot when they realized that DNA segments can pass from one bacterium to another even if from distant species. It's like the giraffe's long neck turns into a duck."

Expanding the tree of life model
The phenomenon of lateral exchange of genes between creatures of different species requires the expansion of the tree of life model, and affects the concept of the organism and its closest molecular ancestors and provides examples of natural selection operating at several levels. Gene exchange, whether through the method of lateral gene transfer, fusion (hybridization) of species, or symbiosis turns the tree of life into a kind of network."

"Darwin proposed to draw the tree of life in the structure of coral, where the living branches on the surface are supported by a mass of dead branches. In phylogenetic trees, the molecular lifelines of organisms finally merge into a lucky ancestor whose descendants are found in the current lineages that coexisted with the extinct lineages. The lateral gene exchange complicates the reconstruction of the ancestor. Genes or the entire genome can belong to different evolutionary histories, and even infrequent transfers of genes will cause different molecular lineages to merge after their molecular ancestors existed in different living lineages at different times."

"Unfortunately, we see that creatures can suddenly acquire traits they need to live in a changing environment, such as resistance to antibiotics that can pass between distant organisms. The transfer is done simply by splicing a DNA segment encoding this ability between bacteria of different species.

Dr. Uri Gofna
Dr. Uri Gofna

One of the functions of the vertical transfer of genes is the ability to receive new metabolic combinations when genes that were involved in one pathway become involved in another metabolic pathway. One of the paths we discovered was transmitted in this way - the ability of a micro-organism to live from the production of methane, in the methanogen archaea, which are responsible for producing 40% of the methane on Earth. There are archaea that produce methane from acetic acid. They can do this because they received genes that are from a group of bacteria distant from them Clostirdia, when these genes joined the ancient genes for methane production (from hydrogen and (CO2) these archaea began to produce methane much more efficiently. Bacteria (bacteria) Archaea and Eukarya (the group to which the complex unicellular organisms belong more, as well as all other multicellular creatures (- they are evolutionarily distant groups that separated billions of years ago - the difference between birds and mammals is much smaller.

Other basic features also came to us this way - photosynthesis for example. The gene of cyanobacteria in which one mechanism of primitive photosynthesis worked was fused within a cyanobacterium from another family that had a second mechanism. This encounter created a more efficient mechanism in which the creature used water molecules to donate an electron and produce oxygen. This encounter gave birth to the oxygen-rich atmosphere as we know it today and changed the course of life.

The research in Israel - a molecular parasite that penetrates genes with the help of domesticated endonucleases

While Dr. Gugraten investigates the entire range of gene transfer between different creatures: their role in the ancient history of evolution, and natural processes that exist today, in the joint research with Dr. Gofna at Tel Aviv University, the two produce this variation in the laboratory and study its consequences. They study a molecular parasite known as an intein, which penetrates genes with the help of endonucleases (enzymes that know how to cut DNA) from homing endonucleases.

"These parasites are excellent examples of Richard Dawkins' concept of the selfish gene - that is, the idea that genes should be thought of as the only natural selection in themselves. These genes have their own life cycle that includes penetration, nesting and settling at the target site, decay and loss.

The research question that I and my colleagues in Tel Aviv (including Uri Gofna, Lilach Hadani, Adi Barzel and others) is under what conditions can these parasitic genes exist in a specific population. For example, the individual gene still follows its life cycle, but the concentration of parasitic activity has reached an equilibrium."

Dr. Gofna explains, "The group of Gugraten and his colleagues from Tel Aviv University is studying the parasitic genes in archaea isolated from the Dead Sea. These enzymes make a cut in the DNA. When the organism approaches to repair the cut, it copies the foreign segment in the process and the parasitic entity enters the new genome.

This enzyme cannot be cut in too many places because otherwise it will kill the creature, for example it cannot enter the middle of a garden, because it will interfere with its activity and then the parasite will die together with the host. To solve the problem they enter only within a DNA component known as an intron or intein. These parasitic genes are also known for their activity in other unicellular organisms: in addition to archaea, also in bacteria and in the mitochondria of eukaryotic organisms. We are trying to cure this archaeon of the parasite and see what the effects will be. So far this has not been done in any creature, and we hope to be able to find the conditions under which we can see a positive or negative effect of removing the parasite on the archaeon."

"In the first step, we examined a species that does not contain this parasite and compared its evolutionary competence compared to other archaea of ​​its kind that contain the parasite, i.e. which one grows faster. We didn't find any effect, apparently we don't know enough about the growing conditions of the archaeon or alternatively, the parasite does no harm, as it takes care of replicating itself for future generations."

In conclusion, Prof. Gugraten says that lateral transfer of genes, as well as symbiosis, provides a mechanism for integrating and expanding the level of organization in which natural selection operates, and contributes to selection at the group and community level. Other works on the way include comparing the genomes of bacteria, and researching ways to map the evolutionary path of the genes and the metabolic pathways into a tree or rather a web of life.

Prof. Gugraten admires the quality of the researchers he works with in Tel Aviv. According to him, when he arrived in Israel, he was surprised to see that mutual activity between groups from different fields is very common in Israel, "In the group I work with there are researchers from plant sciences, from life sciences, from mathematics, it is amazing to see how easy it is for people from different scientific backgrounds and from different groups to carry out a research project. In other universities that are not in Israel it is much more complicated, because first of all you have to establish contact between the professors who would appoint representatives on their behalf and it would take a long time for the project to get underway. Here the process is smooth."

"I'm more of a historian, interested in understanding how evolution created the life we ​​see around us. I'm less practical, so I'm interested in working with students who will later go into fields like genetic engineering and make these studies practical," Gograten explains.

Professor Peter Gograten was in Israel as part of the American Fulbright Program for the exchange of lecturers and students. Israel's participation in this program is managed by USA-Israel Education Fund.

Prosper Gugraten's visit to Tel Aviv University as a Fulbright Fellow was made possible thanks to supplementary funding received from the Edmond Safra Program for Bioinformatics.

17 תגובות

  1. Accumulation of random mutations in bio which are point mutations and whether replication or deletion of entire genes are too slow in the severe evolutionary competition.
    A solution of receiving external DNA in a stressed state makes sense when the alternative is to die. The problem is that there is not too much selection on what we will enter, it is closer to a roulette bet.
    Matrimonial reproduction means receiving DNA from a close and surviving creature, and this greatly improves the chances of receiving a different, normal, and possibly improved combination.

  2. Uncle:
    As with any Hebrew word - the phrase "biological sex" is also ambiguous.
    As mentioned - almost every word has an ambiguity (see entry The stacking paradox )

    This does not prevent us from using the words and the expression "biological sex" is allowed and should be used.
    If you want an explanation of the different ways in which biological sex is defined, you are welcome to read, for example, here:
    http://www.talkorigins.org/faqs/faq-speciation.html

    And in relation to horizontal transfer versus vertical transfer:
    Vertical transfer of genes is their transfer from the parents.
    Horizontal transfer is transfer from those who are not the parents.
    It's that simple.

  3. First of all, it is not clear to me what the difference is between horizontal gene transfer and vertical transfer.
    Everyone recognizes the fact that all the individuals that make up a population of a defined species (by us) are different from each other (even identical twins). When does a particular individual belong to a certain species and when does it belong to another species? This is a question that is difficult to answer objectively. Usually a test of the parents is used as an accepted method for such association.
    When the difference of offspring seems large relative to the average population it is common to decide that the new population will be defined as a new species evolved from the old species. A number of problems arise here. Does a child born to parents whose sex cells have changed drastically as a result of the parents' exposure to strong radiation or to certain substances still belong to his parents' sex even if he clearly resembles an individual of another sex? To which species would a creature that developed from a sex cell identical to that existing in an individual of a certain species, created by the synthesis of inorganic elements be associated (an achievement that is expected to appear in the coming years)

  4. You need to differentiate between macroevolution and microevolution. Even a dog can change color in a wave of mutation. However, it will always remain a dog.

  5. S.:
    You're the best mind reader. How do you know what I think?
    I posed a question here, I didn't claim to have the answers.

  6. Horizontal gene transfer is the best evidence I have ever seen for evolution.
    If creatures were created by God and do not change as Bible and creationists say,
    So the proof that bacteria, for example, change all the time is a complete refutation of the creationist Bible

  7. I think one of the goals of evolution, among other things, is to explain the freak show in the comments above me.

  8. Nahum,

    There is no such question as "Who created man?" Even if the question is grammatically correct, as well as "how is a blue cat"?
    That's a stupid question. Why would there be "someone"? Where did this someone come from? And who the hell created it?
    This is a baseless and even meaningless question. That's why science doesn't deal with it.
    But the best you think the answer is "a mysterious invisible being created man, chose a certain genetic group and demands that they worship him by separating foods, not pressing electrical switches on a certain day of the week and muttering words from an ancient book".
    It is logical that out of such illogicality an illogical question would arise.

  9. What is more amazing
    This is how millions of years of evolution did not produce intelligent beings
    Then in a relatively short period of time man, the dolphin, etc. were created.
    Was there a lateral transfer of foreign genes
    Will the human brain also transfer horizontally to monkeys and other creatures.

  10. On the one hand, Gugraten says that this is an example of the concept of the book "The Selfish Gene" by Richard Dawkins, and on the other hand, that it contributes to selection at the group level, when most of Dawkins' book The Selfish Gene is dedicated to showing that selection at the group level is something that does not exist.

  11. Think about a method where children are raised from a herd of raccoons, what grows will be transferred directly to the NBA,

  12. Correct me if I'm wrong, but there is a hidden refutation of evolution here. After all, they always claim that if they find a creature with genes that are supposed to be in a nearby creature but are found in every distant creature, this is a refutation of the claim of common descent. Because the chances of such distant species having similar genes is slim. Not so ?

  13. It doesn't matter what man is made of. The question is who created it. Science does not have the tools or the pretension to try to answer this question.

  14. Human genetics is created from a collection of germs and viruses plus radiation and carcinogens.

    In short, shit

    It's okay, God was made of shit too

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