Mitochondrial DNA

[genebo]

Mitochondrial DNA is the part of the DNA that is located outside the nucleus of the cell. Due to it's location, in mammals it is only passed on by the female.

There is less known about what traits are passed along in mitochondrial DNA than in nuclear DNA. Possibly many of the sex-related traits are passed on or are controlled through here.

This came to mind while I was reviewing the English upgrade program, and a certain conclusion popped out at me. The English required that the upgrade process begin with a female of another breed and a registered male Dexter. The female offspring would be allowed into the grade-up program but the male offspring would not be eligible. This means that the only offspring eligible to be admitted into the upgrade registry would carry 100% of the mitochondrial DNA from the other breed.

Stop and think about that. 100% of the mitochondrial DNA of the grade cow would  be from the other breed.

Repeat the process with a grade cow and a registered Dexter bull and the female offspring would be eligible to be registered as a higher grade cow. Males are ineligible. The higher grade females will all carry 100% of the mitochondrial DNA from the other breed.

Carry this on all the way to the culmination of the grade-up process and the result will be the same: 100% of the mitochondrial DNA will be from the other breed.

It will not be until two generations after the final step of the grade-up process that the possibility of diluting the other breed's mitochondrial DNA could exist.

Whatever key traits exist or are controlled by mitochondrial DNA will survive fully intact throughout the English grade-up program. I'll bet they wish now that they had reversed the process and required the process to start with a Dexter cow and a bull from the other breed. It seems they prejudiced the process in favor of preserving the traits from the other breed.

[wvdexters]

You know that is interesting. I never thought about it before, but you are right. It is only passed from mother to daughter; always a direct unbroken line. This is something to really think about.

So every female "graded up" into the Dexter breed would therefor be carrying 100% of the mitochondrial DNA of the Non-Dexter (foreign breed). All of her offspring would carry her 100% foreign DNA and it would remain that way through all her offspring. The females would continue to pass on 100% of the foreign DNA continually. The chain would only be broken when the males of the line are bred; as the offspring from these matings would then carry 100% of the mitochondrial DNA of their dams. Wow

[cascade]

Mitochondria are tiny independent living creatures that live inside our cells (and in the cells of all animals). They are like a specialized bacteria, that work as the powerhouses for our cells. As somewhat independent little creatures (like bacteria) with a symbiotic relationship to the animals they inhabit, they have their own DNA that has nothing to do with OUR OWN DNA. When your mother's egg cells are formed, some clones of these bacteria-like mitochondria creatures are passed from your mother's cells into the egg cell that becomes you. Your father's sperm cells do NOT have these bacteria-like creatures called mitochondria. So your mitochondria are clones of your mother's mitochondria.

NONE of our own traits are in the DNA of these bacteria-like mitochondria.... But the mitochondria's own traits are in the mitochondria's dna. These little creatures have very limited (but important) functions within our cells. But if these creatures have a defect mutation in their DNA, then they won't be able to perform their limited functions very well and that affects the life of the human or the animal.

Mitochondria do NOT sexually reproduce, so they are just clones of each other. Mitochondria have very few genes.. a mere 37 genes in many cases. It's likely that many different British breeds of cattle all share identical mitochondria. Mutations in mitochondria DNA are very rare, because there are so few genes to mutate.

Keep in mind that the mitochondria are NOT the only microscopic creatures that have formed a symbiotic relationship with animals. There are trillions of (mostly friendly) important microscopic creatures that live in the gut of animals. These microscopic creatures also each have their own DNA and they affect the animal too. So we humans and animals actually have within us far more DNA from these other symbiotic creatures including mitochondria, than we have of our own DNA.

So if you consider ALL the DNA your cow has contained within her (including all the dna of the microscopic flora and fauna) then your cow has tons of DNA from the mixed breed animals you've had on your farm in the past and DNA from non-dexter cows (and even some non-cows) in your general area.

So if you want to consider the ALL the DNA contained within your purest Dexters... then you've got a real DNA mishmash on your hands. I wouldn't dwell on that overwhelming thought too long.... but it is nice to understand it.


PS. My own mitochondria come from Denmark, because that's where my mother's mother's mother's mother came from. But all the dna of of the trillions of microbes that are also part of me, come from all over the world and from every handrail that I touch and every toilet seat that I sit on and even the air that I breathe.

[jamshundred]

Second that Karrie!  Fascinating to think on Gene.  Thank you for starting this topic!  You hear breeders constantly remark on the one hand that animals used for upgrading were done so to " improve the breed", and then on the other hand, they say all that influence passes in just four generations.   HUH?    The udders Lucifer's dam was supposed to improve are no longer improved?  Those genetics are gone?   What about his red color?  Gone?   Platinum's grandmother is still removing horns in our breed, and whatever the genetics were she carried they are still changing the look of Dexters phenotype drastically.

I was thinking about this DNA.   I used to do lots of human family-line research.  It is said all our mitochondria DNA can be traced to it's origins, and they are now DNA typing men to determine family groups and immigration patterns.  It does NOT disappear in FOUR generations.  Or Fourteen.   Or Forty.

I was thinking about my own family and it dawned on me that most of us resemble some one or another female in our lineage.  Fascinating topic.

Judy

[genebo]

Mitochondrial DNA does exist in males. They get it from their female parents. However, they can not pass it on to their offspring. It only passes down through the egg, not the sperm.

Nuclear DNA is passed down equally by both sexes. One half of the nuclear DNA needed to create a new life is contained in the egg and the sperm. Only the egg contains mitochondrial DNA.

Each new life created will contain a full share of both mitochondrial and nuclear DNA. It's just that the source of the mitochondrial DNA is always the egg, which carries the dam's mitochondrial DNA.

In the English upgrade program, the bulls were required to be registered fullblooded Dexters, with a full compement of Dexter mitochondrial DNA. However, they could not pass that Dexter mitochondrial DNA down to their offspring. The English were not aware of this, and made their rules in the belief that their plan would prejudice the offspring to be more like a Dexter than the other breed. It wasn't until years later that the importance of mitochondrial DNA was discovered.

A lesson to be learned from this is that we should never underestimate the importance of trying to change a breed. No matter how well we think we understand the process of sexual reproduction, we do not understand it completely. The goal of the Swiss Village Foundation is to preserve the genetic material of every breed, to provide a source of genetic material that can be used to retreat from a bad breeding decision.

Brenn's semen is stored there. I would love to see semen added to their vault from Legacy bulls. I would also love to see some Legacy cows flushed and have their embryos added to the vault. Then no matter what the modernists do, no matter how far they carry the genetic dilution of the breed, it can always be re-created.

[cascade]

100% of all mitochondrial dna in ALL Dexters is cloned from their mother's mother's mother's mother's mother's mother's non-dexter mitochondria. If you trace back the mother line of the very purest of dexters, you will find that ALL the mitochondria are clones of mitochondria from other breeds of cattle. There is no such thing as "dexter" mitochondria. Dexters are a modern breed (only been around 100-200 years), and they came from tons of different maternal lines from tons of other breeds.

So the "legacy" dexters you are talking about, all have 100% non-dexter mitochondrial DNA

Concerning their own nuclear DNA (actual DNA of the animal, found in the cell nucleus), what makes dexters, "Dexters" is ongoing selection of defined Dexter traits. "Legacy" bulls that aren't well selected, can have VERY non-dexter traits. Meanwhile, Non-Legacy-on-paper bulls that are well-selected for "legacy" traits, can be some of the best "Legacy" dexter representatives.

Until you can make an exacting list of what you consider to be "Legacy" Dexter Traits, you have no hope of preserving "legacy" dexters, other than on paper.

If you want to really support your cause, then consider making a "legacy" trait selection list explaining to folks the traits they SHOULD be selecting for, vs. the traits they should be avoiding.

Here's my starter list... what would you add/change?

1. Bulls MUST be VERY friendly and VERY manageable, with lots of personality.

2. Cows MUST be sweet and let us work with their newborn calves (tagging/weighing, etc), and should have lots of personality.

3. Dexters must be COMPACT (not too large, not too small) Bulls between 38" - 44" at 3 years, should NOT be too leggy.

4. Dexters must be Black, Dun, or Red... no white other than near udders up to navel (white hairs in tail switch are ok)

5. Dexters must be Healthy and Hardy - can thrive and easily calve robust calves WITHOUT much shelter (other than trees/shade). Can thrive without a lot of chemicals, without a lot of vet work, without a lot of shots. Dexters should have naturally STRONG immune systems.

6. Dexters must be Thrifty - can thrive on forage and minerals alone WITHOUT grain supplements.

7. Dexters must be Dual (or triple) purpose and productive... Beefy, and milky enough, but not so milky that they MUST be milked. Could be used to do work as oxen if necessary

8. Dexters should have Lots of good general cattle conformation (sound udders, sound feet, strong backs, correct legs, good tracking, masculine bulls, etc.)

9. Dexters should be long-lived... Cows should make it to 18+ healthy productive years with no early arthritis, Bulls should make it to 13+ healthy years (if you don't eat them first).

10. While horns look terrific, some folks have been dehorning dexters for eons.... so both horned dexters, and dexters without horns are traditional. If really can't tolerate horns and you're going to de-horn, then you should consider using the polled gene that humanely removes horns.

[lonecowhand]

Oh, the list...

I'd add this , they need to be undiluted (uncrossed, un-upgraded) by other breeds since the establishment of the Breed, and I'd put THAT as number one. (and that fairly negates your #10)

[Deleted]

First I will say I know nothing about Mitochondrial DNA. If it is true that it can only come from the maternal side. Then every bovine would have the exact same clone of it.
I have herd it said that you should only select bulls from good maternal lines because that is where they get their Mitochondrial DNA. I say it makes no difference because the bull calf would have no ability to pass it on anyway. I am not saying that the maternal line is not important it is equally important to the paternal line. but not because of Mitochondrial DNA.

[cascade]

Apr 14, 2015 20:03:49 GMT lonecowhand said:

Oh, the list...

I'd add this , they need to be undiluted (uncrossed, un-upgraded) by other breeds since the establishment of the Breed, and I'd put THAT as number one. (and that fairly negates your #10)

The only problem with that, is that you can assume that EVERY dexter including legacy dexters has had accidental crosses and accidental "upgrades" since the establishment of the breed....   so that brings you back to having a list of features that you are selecting for and other features you are selecting against.... I have no problem if you want to select for horned dexters as part of a "legacy" program... I'm glad some breeders are wanting horns because they look great....  I had a guy call me yesterday looking for dexters and I asked him whether he cared about horns vs. no horns....  He seemed to be slightly leaning toward horns so I didn't hesitate to send him to someone with horned dexters  (I didn't try to sell him on polled dexters).    He also didn't care about color, but he did care about getting a good bargain... So I suggested that he look for some good, friendly, black, horned dexters and gave him some names of breeders.


  

[cascade]

Apr 14, 2015 20:43:57 GMT @dexterfarm said:

First I will say I know nothing about Mitochondrial DNA. If it is true that it can only come from the maternal side. Then every bovine would have the exact same clone of it.
I have herd it said that you should only select bulls from good maternal lines because that is where they get their Mitochondrial DNA. I say it makes no difference because the bull calf would have no ability to pass it on anyway. I am not saying that the maternal line is not important it is equally important to the paternal line. but not because of Mitochondrial DNA.

Over VERY long periods of time, the DNA of the mitochondria can accumulate mutations... so even though all bovine mitochondria are clones from the original bovine "Eve",  there are likely some accumulated mutational differences in the mitochondrial DNA from one old female line to another old female line.... In humans, you can have your mitochondrial DNA tested and find which of the handful of old female lines you come from.  

But since the mitochondria are just little bacteria-like creatures with a specific limited (but important) job to do, you are correct that most all of the actual maternal line traits have nothing to do with the mitochondria or the mitochondria's DNA.... but broken mitochondria, certainly can be problematic.   If a calf is born with broken mitochondria due to some bad mutation... it's an easy matter to simply cull the problematic calf.    You wouldn't know it was the mitochondria that was the problem, you'd just observe the negative effects. 

[wvdexters]

Like I said very interesting topic - Breeders have been talking about mitochondrial DNA for many years, and it is so remarkable when you stop and consider that it is only passed down through the females. From Mothers to their offspring - males play no part in inheritance.

This topic is pretty new to me, but I did do a little reading and it really is very interesting. The mitochondria are basically the "power houses" of the cells. But not only do they provide the energy to the cell, they control cell function also. What effect they have within the different cattle breeds is a question. If there are differences in the mitochondria within the breeds? If there is a lot of variation or if they are all quite similar? Interesting. I wonder if this has even been studied.

However there is quite a long list of problems/diseases that do occur when there is a problem/defect in the mitochondria. All kinds of problems from cancers, diabetes, syndromes etc. These would carry down the female side of the family line as they could only be inherited from their mothers.

This is my own mind working here (like I said this is a very interesting topic and with so much to learn) but with the mitochondria basically being responsible for a great deal of the function of the cell as well as generating the energy for the cell, I wonder what effects slight differences could make. Might some mitochondrial "lines" be better than others? I'm thinking about areas like thriftiness, or perhaps allowing the individual to be more adaptable or hardy? Like I said this is just my mind questioning and it would definitely take a great deal of research to answer them. Very interesting subject across the board.

I do think that it would be wise to really look at that female when considering her for our breeding program. While the sire is very important our future calves will be inheriting a great deal from her alone.

[genebo]

In order to better understand the importance of the female in breeding choices, look up and read some of Gearld Fry's writings.

[wvdexters]

Apr 14, 2015 17:29:09 GMT cascade said:

100% of all mitochondrial dna in ALL Dexters is cloned from their mother's mother's mother's mother's mother's mother's non-dexter mitochondria. If you trace back the mother line of the very purest of dexters, you will find that ALL the mitochondria are clones of mitochondria from other breeds of cattle. There is no such thing as "dexter" mitochondria. Dexters are a modern breed (only been around 100-200 years), and they came from tons of different maternal lines from tons of other breeds.

So the "legacy" dexters you are talking about, all have 100% non-dexter mitochondrial DNA

Concerning their own nuclear DNA (actual DNA of the animal, found in the cell nucleus), what makes dexters, "Dexters" is ongoing selection of defined Dexter traits. "Legacy" bulls that aren't well selected, can have VERY non-dexter traits. Meanwhile, Non-Legacy-on-paper bulls that are well-selected for "legacy" traits, can be some of the best "Legacy" dexter representatives.

Until you can make an exacting list of what you consider to be "Legacy" Dexter Traits, you have no hope of preserving "legacy" dexters, other than on paper.

If you want to really support your cause, then consider making a "legacy" trait selection list explaining to folks the traits they SHOULD be selecting for, vs. the traits they should be avoiding.

Here's my starter list... what would you add/change?

1. Bulls MUST be VERY friendly and VERY manageable, with lots of personality.

2. Cows MUST be sweet and let us work with their newborn calves (tagging/weighing, etc), and should have lots of personality.

3. Dexters must be COMPACT (not too large, not too small) Bulls between 38" - 44" at 3 years, should NOT be too leggy.

4. Dexters must be Black, Dun, or Red... no white other than near udders up to navel (white hairs in tail switch are ok)

5. Dexters must be Healthy and Hardy - can thrive and easily calve robust calves WITHOUT much shelter (other than trees/shade). Can thrive without a lot of chemicals, without a lot of vet work, without a lot of shots. Dexters should have naturally STRONG immune systems.

6. Dexters must be Thrifty - can thrive on forage and minerals alone WITHOUT grain supplements.

7. Dexters must be Dual (or triple) purpose and productive... Beefy, and milky enough, but not so milky that they MUST be milked. Could be used to do work as oxen if necessary

8. Dexters should have Lots of good general cattle conformation (sound udders, sound feet, strong backs, correct legs, good tracking, masculine bulls, etc.)

9. Dexters should be long-lived... Cows should make it to 18+ healthy productive years with no early arthritis, Bulls should make it to 13+ healthy years (if you don't eat them first).

10. While horns look terrific, some folks have been dehorning dexters for eons.... so both horned dexters, and dexters without horns are traditional. If really can't tolerate horns and you're going to de-horn, then you should consider using the polled gene that humanely removes horns.   



 

I would like to discuss this posting but am unable to do so here because it would be hi-jacking the thread.  This thread is about mitochondrial DNA not creating a list of "dexter traits".   I ask the moderator to please move this post as well as my reply to a new thread of its own. 

Kirk,  This list keeps popping up on just about every thread you participate in.  I can see that it is very important to you and that you have given it a great deal of thought and have put a lot of time into it.  Like I have said in the past; it is a good list full of excellent cattle traits.  But there are a lot of major problems with it from a Dexter breeders point of view.  This is of course my opinion, but as this list is merely your opinion, I believe it is valid .

1-8 are all excellent traits for cattle in general.  Except for the height requirement you have listed and perhaps the color, I would believe that these traits would be included in just about every breed's list of desired traits. 

9.  As I have said before I'm not sure where you get these ages as I have not seen too many 18 yr olds around breeding BUT OK.  We agree that health and longevity are certainly important.

Like I said - Good List.  All great characteristics of cattle.  But here's the problem......and it is a big one.  They are just that - a list of great cattle characteristics.  Simple

These traits you describe as "What makes a Dexter a Dexter" could pertain to just about any breed and to millions of animals that do not now have nor have they ever had in their lineage one drop of Dexter blood.   THEY ARE NOT DEXTERS!!!!! 

Kirk  a Low-line is NOT a Dexter!  A jersey x angus is NOT a Dexter!  The mixed breed cattle that I see grazing in the pastures all around here are not Dexters!  Yes, they are small, the right color, they may even be very friendly with wonderful personalities but that doesn't make them a member of the Dexter Breed.   Thrifty, long-lived animals with good conformation are just that - thrifty long-lived animals that look good.  Any old black cow that gives some extra milk while raising her calf doesn't GET to be called a Dexter. 

This is not a club- it is a BREED.  A heritage breed.  Dexter is not an adjective - It is a noun.  You neglected to list the MOST IMPORTANT thing that makes a DEXTER a DEXTER.  The animal must be BORN a Dexter.  From parents that ARE Dexters.   This as we both know (as we all know) is the first and most important fact and should be number 1 on your list.  It should be #1 on every Dexter Breeder's List.  Look at it this way.  A little heifer born on our farm is not a Low-line, nor is she a Devon, jersey, or whatever.   She may fit someone's list of desired traits for Low-lines but that doesn't make her one.  She is a Dexter, born of Dexter parents.  Plain and Simple.

My list > 1. Must be born of Registered Dexter parents.  Sire and Dam.  And so-on back through the line. 

Now we are talking about Dexters.

Now for #10 on your list.  Horns...........  I understand that this is something you really want.  But the facts do not support your position.

 

Taken directly from the 1921 Herd Book

 

The characteristics of the Dexter. In Great Britain the Dexter is regarded as a diminutive dual-purpose breed, although in the United States the beef side is given scant consideration. The essential characteristics are found in the head, short legs, small size, and color. The head is old-fashioned in a degree, tending towards plainness and crowned with more or less blacktipped, upright horns. The head of the bull is burlv and short and the horns often extend* directly out to each si'ie and then make a wide curve forward and upward, with considerable spare between the tii^s. The neck is moderately short and muscular, the zvithcrs show a dual-purpose thickness, the hack isunusuallv strongly supported, the depth of body and digestive caoacitv is comparativelv great, the /a/7 head is often prominent, the hind quarters suggest the dual-purpose type (more especially with the bull), the legs are very short, and the udder on mature cows frequently indicates great capacity for animals of such
small size.

Taken directly from The Livestock Conservancy

Dexter cattle are solid and compact in appearance. Most Dexters are black, though red and dun are also found. The cattle are horned, and their black‑tipped white horns arc upward. Two body conformations are found within the breed: cattle with normal bodies and very short legs, and cattle, which are proportionately small in every dimension.

Taken from the Journal of the Royal Agricultural Society of England 1898

The Dexter has a round plump body,  square behind, short legs and thick with the hoofs inclined to be turned in; the head is heavy, and wanting in that fineness and life which the head of the true Kerry possesses; and the horns of the Dexter are inclined to be long and straight.

The Dexter Breed was always a Horned Breed.  Dexters have horns!!!  FACT

10. While horns look terrific, (opinion - to which I personally agree.)  They are beautiful.

some folks have been dehorning dexters for eons....(Fiction)  While the practice of dehorning cattle has been around for centuries, the Dexter Breed has not.

so both horned dexters, and dexters without horns are traditional.  (Fiction) and absolutely UNTRUE.  Through all the historical documentation Dexter cattle are always described as horned cattle.  The breed is described as a horned breed. 

If really can't tolerate horns and you're going to de-horn, then you should consider using the polled gene that humanely removes horns.  (Opinion)  

Polled was not part of the Dexter Breed.  It is not traditional and never will be.  The ADCA chose to allow polled animals into the registry under threat of legal action and under great controversy.  To this day, decades later,  they still refuse to release any details about how the decision was made, or about the vote or even if there ever really was one. 

All polled animals in this country are from upgraded lines, from one bull with many instances of outcrossing in his pedigree.  It is important to remember that this is within an association that does not even allow upgrading.   Kirk you can keep saying that this is traditional but we both know it isn't.  Simply repeating something that you know is untrue over and over doesn't make it turn true all of a sudden.  It just gets worn.  Wouldn't it be better just to accept the truth and move on?  For everybody?  Polled dexters are not traditional to the breed.  They are newcomers and have a large following.   

   

         

[cascade]

Didn't mean to take this off topic.... I'm just reiterating the fact that if you want to keep "traditional" or "legacy" dexters looking and behaving a certain way, you shouldn't get too caught up in mitochondrial DNA lineages, or ancient old pedigrees, but rather you should select dexters each generation based on a list of traits that you believe make a dexter "traditional" in reality, and NOT just some paper-concept of what "traditional" means.

I've seen people say "I'm looking for a traditional bull" or "I'm looking for a legacy bull" without even caring about the physical and behavioral traits of the animal. I'd hate to see people start looking for XYZ mitochondria and testing for it, further detracting from caring about the actual physical and behavioral makeup of the animal.



PS... If you choose to say that horns are important to "traditional" dexters.... I can accept your definition of that, but it would seem that you'd have to disqualify de-horned dexters from being traditional. The polled gene doesn't eliminate the horned genetics (they're still there)... the polled gene simply "de-horns" dexters in the very most humane way possible.