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DNA That Should Only Pass Down From Mothers Can Come From Fathers, Too

Fibroblasts, or connective tissue cells. Nucleus in blue, mitochondria in green. Image: NICHD (Flickr) You probably learned two things about…

Fibroblasts, or connective tissue cells. Nucleus in blue, mitochondria in green. Image: NICHD (Flickr)

You probably learned two things about mitochondria in high school biology. Først, de er de powerhouses of the cell. Second, you can only inherit them from your mother. Men en ny undersøgelse synes at skyte den anden punkt.

A team of researchers from the United States, China, and Taiwan identified three unrelated families with members whose mitochondria contained DNA from both parents. Mens denne discovery kan reignite debat om naturen af ​​eterende mitochondrial DNA, forskerne håber det vil åbne nye måder at behandle sygdom.

The story began when a four-year-old patient suffering from fatigue and muscle pain was referred to physician-scientist Taosheng Huang at the Cincinnati Children‘s Hospital Medical Center. Others had suggested that the boy was showing signs of a mitochondrial disorder, so Huang sequenced and analyzed the boy’s mitochondrial DNA and found an abnormally high level of “heteroplasmy,” meaning different mitochondria seemed to contain different genes.

Mystified, he sequenced de mitochondrial DNA of the boy’s other family members, including his sisters, parents, grandparents, and siblings of his parents and grandparents. Det viste sig at han hadde, som forventet, hans rare mitokondrier fra hans mor, som delte det høje niveauet av heteroplasmy. Men videre analyse viste at hans mor, farfar, og to af hans store aunts havde arvet mitochondrial DNA fra begge foreldre.

Huang reached out to other labs, looking for families with members who similarly had high levels of heteroplasmy. Hij vond twee met vergelijkbare patronen, waar bepaalde individuen bleken erfelijk mitochondrial DNA van beide ouders, welke moeders dan zouden doorgeven aan hun eigen kinderen. And to further remove doubt, Huang enlisted the Baylor College of Medicine to take independent blood samples and sequence the three families’ mitochondrial DNA on their own. Their results confirmed Huang’s.

These results are naturally provocative, as several other attempts to show mitochondrial DNA passed from both parents or from the father to the child have turned up negative. Gizmodo has reached out to several outside sources for comment, and will update the post when we hear back. Det er uklart hvordan male mitochondria ville gøre det til en æg, siden egget ødelegger spermens mitokondrier etter befruktning. The new paper, published in the Proceedings of the National Academies of Sciences, proposes that perhaps a mutation turns off the egg’s mitochondrial elimination abilities.

This study probably does not have major implications on evolutionary timescales where maternal inheritance remains “absolutely dominant , “The authors write-it’s an exception to a rule. But Huang was more interested in what the result could mean for treating disease.

You may be familiar with another project, in which researchers produced a baby from three parents-an egg from a donor, the nucleus from a mother, and sperm from a father. Dit was om te voorkomen dat de moeder van passeren langs Leigh syndroom. “It’s a very complicated and costly procedure,” Huang explained to Gizmodo. Perhaps, if they can find the mechanism by which to transfer the father’s mitochondria instead of the mother’s, they would be able to offer these options without the three parent procedure.

It seems it can sometimes be hard to find firm rules in biology, even when it comes to the most well-accepted facts.

[PNAS]

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Faela