Friday , July 1 2022

Dads, too, in the mitochondrial DNA passage NOVA | PBS | NEW


For the first time, when Taosheng Huang saw the test results, it was certain that a mistake had occurred. After a diagnosis by a technician, Huang did not believe it. "That is impossible," he said.

Huang, a pediatrician and geneticist at the Cincinnati Children's Hospital Medical Center, asked the patient to return to new blood samples to reduce mistakes that Huang could have distributed among some research laboratories. Huang knew that knowing that he broke off a major human genetic model, but repeatedly, the same result was.

Huang's patient, a four-year-old boy, made two different sets of mitochondrial DNA: his mother, one planned, and another from his father.

This was just the beginning. Using the modern DNA sequencing technology, Huang and his colleagues have demonstrated a paternal DNA-proven DNA mitocondrian with 17 different people. He is currently working on the magazine PNAS

"This is a truly positive discovery," says mongolian biologist Xinnan Wang Stanford University, but does not participate in new discoveries. "A completely new field can be opened … and change the way we look for the cause [certain] illnesses. "

In general, we are both mum and father of each genetic mix. The nucleus, which has our chromosomes, is true. But the nucleus is not the only part of the cell that has DNA. Cells contain power centers called mitochondria, they also make DNA sets, and they are often known as animals. Mitochondrial DNA is inherited only from motherhood. This lopsided purchase is very rational in the study of mitochondrial DNA frequently investigating traces of mother tongue over time.

Scientists are still not completely sure why This process has become a rigid matrilineal, but some theories have been avant-garde. On the one hand, sperm mitochondria consider higher mutation rates than eggs, making their introduction somewhat dangerous. Additionally, having a single mitochondrial type makes it easier to coordinate the nucleus and mitochondrial genomes because they produce the necessary raw materials for the appropriate functional cell, said Sophie Breton, a mitochondrial genetype at the University of Montreal, and did not participate in the study. Adding another mitochondrial interest group, so the theory goes, can confuse this intimate two-way dialogue.


Blue crystals with cows dyed blue and mitochondrial. Photo: Torsten Wittmann, University of California, San Francisco

Everything that drives the inheritance of the mitochondrial mothers is clear, our cells have taken some measures to maintain them. The brilliant machine of molecular machines is ready to be ready for non-involuntary contributions. Although sperm mitochondria helps strengthen egg hysteria, mitochondria will not last. Some mitochondria lose while sperm develops; Many of those who make it through the fertilization process are labeled with a chemical marker to make it easy to recognize eggs and allow easy access to paternity partners.

Some handful of animals, including birds and mice, occasionally become "endless" father's mitochondrial DNA, in addition to mother's English, humans have historically been excluded. Only a few mitochondrial DNA derivative reports are available, most of which have resulted in contamination or laboratory sample disorders. In one case, the one described in 2002, paid special attention if another research group confirmed it independently. But 16 years later, another example of this genetic abnormality was sought.

That's why Huang's four-year-old patient, when both parents inherited mitochondrial DNA, went away. When researchers made their subsequent genetic signatures through a tree of a boy's family, more than three generations were found when a 10-person family of the patient was confused with mitochondrial DNA. Now, the researchers knew where to look and what to search for when they opened searches. Shortly afterwards, seven additional people from two different families were reaffirmed to be in the same situation.

Surprisingly, all three families show similar characteristics to the inheritance of this unusual feature. Not all partners were disturbed, thinking that some individuals changed their genotypes in conventional fashion, thinking that mothers were only inherited from mitochondrial DNA. But it was clear that the genome of the mitochondrial humans of these families had broken their biological rules of paternity. Instead of excluding, parents of genetic information, in some way, maintained a rhythm with their widows during the fertilization period, leaving some children with a mixed mitochondria.

Thanks to these mixed genomes, daughters sent their heterogeneous heritage with their children, carbon copy. This means that children were necessarily inherited from children, although children did not have mythological DNA mites. Huangan was the original case of the four year old patient.


Sheep are one of the few mice that can be inherited from mothers and daughters. Photo credit: herbert2512, Pixabay

The children who bought mixed mitochondrial genomes present a somewhat more complex image. The ability to overcome the DNA of the participants is a key feature or a single-parent gene requires the offspring to show themselves. This means that the mitochondrial genome was inherited by hybrids that some men could transfer to their children, because they displayed more diversity, mixing Dad's genes with Mom. But men with no disorder maintained this abilities, occasionally at the extremities of the dead.

exactly how The mitochondrial DNA mothers continue to infiltrate embryos. It is definitely genetic, but not ironically, in the mitochondrial genome. In fact, aside from unusual inheritance, there seems to be no disease of any mitochondrial patient. Instead, any type of mitochondrial DNA in your children allows a mutation that is coded in the nucleus, of course. supposed Mom and dad will come.

Florence Marlow, a biologist who develops at Icahn School of Medicine, did not participate in this research, Mount Sinai, explains that the abnormality of mumps of sperm is usually in the process of being labeled destructively. If this labeling step never happens, he explains that the fertilized egg does not have any way of identifying and eliminating links between his father; while his father's mitochondrion lights up with Mom.

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Since the discovery of initial findings, Huang and his team have already identified several mitochondrial DNA mixed families. According to forecasts, this phenomenon can be up to 1,000 people in 1,000 people. Wang emphasizes that further research by other groups is needed to confirm the numbers, according to the work carried out by the Huang team, the mitochondria's father transmission may be wider than the researchers believe.

So how have you forgotten so much time? "Many people have given the maturity of the mumps given," said Breton. "But the sequencing techniques are very strong a few years ago.


Mouse cells from the connective tissue. Cell nuclei are dyed in blue and mitochondria are green. Photo credit: D. Burnette, J. Lippincott-Schwartz / NICHD

Father's father's opportunity in the near future may also include the possibility of reproductive technology support. Huang's team participated in the successful investigation and delivery of the "babysitter" childhood in 2016. As a result of the motherhood of the mother, mitochondrial disease, Huang and his colleagues transferred nuclear DNA to the sun, their chromosomes, but the mitochondria could be healthy. This hybrid egg, being the genetic information of both mother's mother, was fertilized with her father's son.

In theory, Breton suggests that while father's mitochondria is feasible, they could replace mother's mitochondria or maybe substitutes by looking at the need of a third parent.

But this is great, especially for the spermatozoa's mutagenic mutagenic mutation. We do not understand very well the implications of inherited mythical deceased parties, much less by artificial medical procedures, many of which follow ethical discussions.

For now, the inheritance of the mitochondrial DNA mother is still a rule. But when it opens the view of genetic inheritance, several doors are opened. "These results will change the way the mitochondrial heir is described," says Breton. "100 percent I am sure that you will find such cases in the future."

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