Prof. Oded Ravavi's laboratory previously discovered that worms bequeath to their offspring small RNA-type molecules that contain information about the parents' environment, such as nutritional status, infection with viruses and even the brain activity of the parents, thereby contributing to the survival of future generations. In their current study, Prof. Ravavi and his team tried to understand whether there are laws for the epigenetic inheritance of small RNAs over the generations or whether it is a passive and random inheritance
Researchers from Tel Aviv University have revealed three laws that dictate epigenetic inheritance, i.e. inheritance without a path Changes in sequence eDNA, throughout the generations. the research, which was published in the prestigious journal Cell, led by Prof. Oded Ravavi and his student Dr. Leah Khoury-Zavi from the Department of Neurobiology at the Faculty of Life Sciences and the Segol School of Neuroscience at Tel Aviv University.
Most of the experiences we will accumulate during life will not be passed on to our descendants. So for example, our training in the gym today will not make our children stronger. However, in recent years, studies in worms on epigenetic inheritance challenge our concept of the limits of heredity and evolution, and show that there are acquired traits that are indeed inherited. Prof. Ravavi explains that epigenetic inheritance of environmental reactions is inheritance that occurs separately from changes in the DNA sequences, by other inherited molecules. According to him, in many organisms in response to a change in the environment, for example stress, small RNA molecules "silence" or block the expression of certain genes. Studies conducted in recent years with the help of worms C. elegans, very important and common model animals, showed that small RNA molecules can also be passed on to future generations and thus transmit traits from generation to generation.
Prof. Ravavi's laboratory previously discovered that worms bequeath to their offspring small RNA molecules that contain information about the parents' environment, such as nutritional status, viral infection and even the brain activity of the parents, thus contributing to the survival of future generations. In their current study, Prof. Ravavi and his team tried to understand whether there are laws for the epigenetic inheritance of small RNAs over the generations or whether it is a passive and random inheritance.
According to Prof. Ravavi, "the preferred model animal for intergenerational epigenetic research is C. elegans Because the generation time of these worms is three and a half days, so it is possible to study many generations in a short time, and each such worm gives birth to hundreds of offspring - which gives statistical power. It is possible to perfectly control the environmental exposure and in addition, the worm fertilizes itself, so the genetic differences (in DNA) are also almost completely neutralized.
Dr. Khouri-Zavi points out that many laboratories have noticed that the epigenetic inheritance of small RNAs continues in most worms in the population for about three to five generations. According to her, in a previous study conducted in their laboratory, the researchers revealed the mechanism that controls the duration of inheritance, and in fact proved that this inheritance is a controlled process. However, even after this exposure, the question remains as to why some worms inherit the inherited responses in a strong way, while others did not inherit the epigenetic effect at all, even though all the offspring are genetically almost identical. "Although this partial inheritance was known, the way the epigenetic material is distributed in the offspring population remains completely mysterious. We wanted to know if there is some inheritance pattern that explains and predicts who will inherit the epigenetic traits - and for how long," she adds.
for the purpose of the experiment The researchers used a genetically engineered worm, which carries a gene that produces a fluorescent protein and causes the worm to glow under fluorescent light. The researchers activated a silencing reaction inherited by small RNAs against the fluorescent gene and examined which offspring inherited the silencing reaction and stopped glowing, and which offspring "forgot" the parental reaction and returned to express the gene after several generations. Dr. Khouri-Zavi repeated this process again and again, trying to understand the legality behind the epigenetic effect.
"Leah tested dozens of lineages of worms and a total of more than 20,000 individual worms," says Prof. Ravavi, "but the really challenging part of the work was deciphering the different patterns of inheritance, and understanding what is behind them." In the end, and while delving deeper into the mechanism of inheritance, the researchers discovered three laws that can be used to explain and even predict who inherited the epigenetic information:
- The first law: inheritance is uniform between worms that came from the same mother, that is, from the same lineage. The researchers were surprised to find that the differences in inheritance observed so far in previous studies were actually 'masked' by examining populations of worms rather than examining distinct lineages.
- The second law: the inheritance is very different between worms that come from different mothers, even though apparently the mothers are also supposed to be the same, because the worm fertilizes itself. The researchers characterized the mechanism that produces the difference between genetically identical mothers, and found that differences between different offspring stem from different 'internal states' that different - but genetically identical - mothers randomly adopt. In fact, it is the internal state of the mother, the degree of activity of the inheritance mechanism in each and every one, that determines the duration of the inheritance and hence also the fate of future generations.
- The third law: the researchers found that the more generations the epigenetic inheritance lasts in a particular lineage, the greater the chance that the inheritance will continue to the next generation as well - "in a kind of intergenerational momentum, like the 'hot hand rule' in basketball."
According to Prof. Ravavi, it is not yet known whether intergenerational epigenetic inheritance also exists among humans:We hope that the mechanism we discovered also exists in other organisms, but we will have to wait patiently. It should be remembered that genetic research also began with the monk Gregor Mendel's research on peas - and today we use Mendel's laws to predict whether our children will have straight or curly hair."
"The idea of acquired traits that are inherited is as old as it is scandalous, even before Darwin and Lamarck, the Greeks argued about it, and it is not consistent with genetic inheritance according to DNA", adds Prof. Ravavi. "The worms changed the rules by showing us that there is inheritance outside the genetic sequence, the inheritance of small RNAs, with the help of which the parents prepare the offspring for the difficulties to which they were exposed. From study to study we are shedding light on the molecular mechanisms and the mysterious dynamics of epigenetic inheritance, and the current study provides rules and "order in chaos".
More of the topic in Hayadan:
- A mechanism has been deciphered that allows the inheritance of brain activity from generation to generation - not through DNA
- Spotlight: Epigenetics - heredity not only in genes / Dorit Ferns
- The evolution within the evolution
The researchers revealed: three laws that dictate intergenerational epigenetic inheritance - not through changes in the DNA sequence
5 תגובות
tnhr you are simply very wrong. "If" is the "question" of "mother" when it comes to mother it is about hereditary security. When you use the term if you mean something big. if all wars If all the bombs, if all the failures. etc.
Did the researchers examine the possibility that epigenetic inheritance of the type described differs between worms created by self-fertilization (99.9% of this species are bisexual) and between those created with the help of the few males (one in a thousand, approximately) that are created each generation. It is clear that the laws of generalized heredity they propose are more suitable for the environment of self-reproduction, where it is actually difficult to see the fertilized egg as an organism that is not actually an organic part of the mother, like any other cell in her body (that is not on the fertilization track). Therefore, one can expect different levels of inheritance of traits - and especially a distinction between traits acquired from the mother in relation to traits acquired from the mother.
What's happening to the science website? They published my response.
Miracles are you now convinced that I was right about evolution not being random. And in addition, in my opinion, there are no randomness at all in physics either.
Worms have a "mother", not a "mother".
"Mother" is the name a person calls his mother.
The biological function is "if".