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Mitochondrial DNA can come from both parents

arstechnica.com

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Re: Mitochondrial DNA can come from both parents

#21

Post by mbreese »

eridan2 wrote: post #14
ghshephard wrote: post #11

I'm not sure how much of a "plot twist" this is - when I took my biology course decades ago, it was explained to me that both maternal and paternal mitochondria were passed on, but the Egg is so much larger than the sperm, that the impact of of paternal mitochondria, and amount passed on, was relatively minor. I guess the interesting detail here is that the amount present raises to the level of catching a DNA scan.

it is not about the size; paternal mtdna dies after fertilization: https://www.iflscience.com/health-and-medicine/paternal-mito...

That study was in C. elegans. Has anything similar been done in mammals?

Re: Mitochondrial DNA can come from both parents

#22

Post by mbreese »

ArchTypical wrote: post #18
ghshephard wrote: post #11

I'm not sure how much of a "plot twist" this is - when I took my biology course decades ago, it was explained to me that both maternal and paternal mitochondria were passed on, but the Egg is so much larger than the sperm, that the impact of of paternal mitochondria, and amount passed on, was relatively minor. I guess the interesting detail here is that the amount present raises to the level of catching a DNA scan.

> I'm not sure how much of a "plot twist" this is I was taught differently in 1998. There was the press coverage of: https://en.wikipedia.org/wiki/Lucy_(Australopithecus) which was referenced in a scene of https://www.imdb.com/title/tt2872732/ It can be said that it's a plot twist that was stoked for decades.

I remember being taught that there was a paternal component of mtDNA, but that the contribution was really small (<10%, maybe <1%). However, I don't remember if this was undergrad (~ 1998) or grad (~2000)... probably grad school.

Re: Mitochondrial DNA can come from both parents

#24

Post by ArchTypical »

mbreese wrote: post #22
ArchTypical wrote: post #18

Earlier quoted context omitted.

> I'm not sure how much of a "plot twist" this is I was taught differently in 1998. There was the press coverage of: https://en.wikipedia.org/wiki/Lucy_(Australopithecus) which was referenced in a scene of https://www.imdb.com/title/tt2872732/ It can be said that it's a plot twist that was stoked for decades.

I remember being taught that there was a paternal component of mtDNA, but that the contribution was really small (<10%, maybe <1%). However, I don't remember if this was undergrad (~ 1998) or grad (~2000)... probably grad school.

> probably grad school.

I was an undergrad, which still puts us both above the vast majority in education.

Re: Mitochondrial DNA can come from both parents

#25

Post by CWuestefeld »

pbhjpbhj wrote: post #13

Aside: this question came to mind today, is there any discernible genetic component from a surrogate mother (a womb donor, as it were)? It seems highly likely to me a priori ?

Certainly an epigenetic contribution. It turns out that the mother's body during pregnancy can have a huge and heritable impact on the baby. E.g., studies have shown that nutritional problems (like famine) during pregnancy can cause the baby to have obesity problems later in life. These have been shown to be the result not of direct genetics (the fetus's DNA has already been selected), but by causing a different mix of genes to be expressed.

That shouldn't be too surprising. It seems logical that evolution would find a way to prepare a baby to be born into an highly-food-constrained environment so their metabolism will be more conserving of resources.

What really is surprising (at least to me) is that the child's propensity has been observed to be passed down even to the grandchild.

Re: Mitochondrial DNA can come from both parents

#26

Post by qaminsod »

ArchTypical wrote: post #24
mbreese wrote: post #22

Earlier quoted context omitted.

I remember being taught that there was a paternal component of mtDNA, but that the contribution was really small (<10%, maybe <1%). However, I don't remember if this was undergrad (~ 1998) or grad (~2000)... probably grad school.

> probably grad school. I was an undergrad, which still puts us both above the vast majority in education.

Get a room nerds.

Re: Mitochondrial DNA can come from both parents

#27

Post by inetknght »

amelius wrote: post #3

In the age of low-cost DNA sequencing, shouldn't this be simple to figure out?

I work as a software developer at a DNA analysis company with an in-house lab. You might be surprised to know how much knowledge is regurgitated and how little actual research occurs.

Re: Mitochondrial DNA can come from both parents

#28

Post by eggie »

droithomme wrote: post #8
JohnJamesRambo wrote: post #6

Earlier quoted context omitted.

How do you know paternal mitochondrial dna transmission isn’t so rare that it has no real measurable effect on population mapping?

In humans between 1 in 1000 and 1 in 10,000 of the mtDNA is copied from the father, and how much and which parts seems to depend a lot on the particular father, perhaps suggesting that there exists an as yet undiscovered checksum scheme, and not random chance. Most mtDNA between humans is the same, and mtDNA is only 16,569 base pairs long. So in most offspring the paternal mtDNA contribution of 1-20 base pairs happen…

> undiscovered checksum scheme

I don't think checksum is a fair metaphor for anything happening in biological systems.

> Most mtDNA between humans is the same

And most DNA is also the same. A percent difference is the kind of thing that would require millions of years of divergence to develop.

> mtDNA is only 16,569 base pairs long

This is really not so precise. There will be a mixture of lengths due to insertions and deletions, even in the same individual, even in the same cell.

> The differences between mother and child are almost always due to the father's contribution, and not to mutations.

Do you have a citation for this?

Re: Mitochondrial DNA can come from both parents

#29

Post by eggie »

ghshephard wrote: post #11

I'm not sure how much of a "plot twist" this is - when I took my biology course decades ago, it was explained to me that both maternal and paternal mitochondria were passed on, but the Egg is so much larger than the sperm, that the impact of of paternal mitochondria, and amount passed on, was relatively minor. I guess the interesting detail here is that the amount present raises to the level of catching a DNA scan.

I agree. However, it can be hard to observe, even in the large, public sequencing data that is currently available. There is a large amount of mtDNA inserted into the nuclear genome, and this can make it appear that there is rampant heteroplasmy until you control for it. The actual contribution is extremely hard to observe.

Re: Mitochondrial DNA can come from both parents

#30

Post by Retric »

eggie wrote: post #28
droithomme wrote: post #8

Earlier quoted context omitted.

In humans between 1 in 1000 and 1 in 10,000 of the mtDNA is copied from the father, and how much and which parts seems to depend a lot on the particular father, perhaps suggesting that there exists an as yet undiscovered checksum scheme, and not random chance. Most mtDNA between humans is the same, and mtDNA is only 16,569 base pairs long. So in most offspring the paternal mtDNA contribution of 1-20 base pairs happen…

> undiscovered checksum scheme I don't think checksum is a fair metaphor for anything happening in biological systems. > Most mtDNA between humans is the same And most DNA is also the same. A percent difference is the kind of thing that would require millions of years of divergence to develop. > mtDNA is only 16,569 base pairs long This is really not so precise. There will be a mixture of lengths due to insertions an…

Checksum is a solid analogy, take natural abortion. If a fetus fails specific challenges it’s removed. This is very common, with a significant portion of pregnancy’s ending this way.
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