This is probably out of my depth of understanding, but it rambled into my mind the other day and won’t go away until I post it here:
Do dogs ( or other animals for that matter) have DNA? What I’m wondering is:
1)Say a chihuahua bit me but I did not see it bite me and I had a bit of its saliva or fur (what fur it has), and it was examined by the DNA doctors, would these fragments definitively tell what kind of dog bit me?
If you had a mutt and didn’t know what breeds were floating around inside’s its genetic structure, would a blood test tell you that Scout is part Rottweiler, Part blood hound and part corgi?
The problem with DNA in TV criminal cases is you have to have someone to match up with the sample from the crime. It is exactly like fingerprints.
I’m sure you could get someone to DNA test your dog’s puppies and your neighbor’s male dog to see if it sired those puppies but the cost might run between $300-500.
To the best of my memory no one has yet run out the specs for dogs (or people) - it would be a complicated job and costly to boot.
What do you mean, “the specs”? They have one chromosome of the human genome deciphered and claim they’ll be finished with the 20-odd set in 2 or 3 yr. I assume other species will be somewhat trivial after that, except in justification of the cost.
I thought the question was usually whether the dog had rabies.
Yes all cellular organisms have DNA. Many viruses do, as well, although many others use RNA as their genetic script, with special enzymes (like reverse transcriptase) to allow themselves to replicate.
Dogs have DNA. Large enough fragments of dog DNA could probably reliably be identified as dog DNA, but I don’t know that anyone has codified the differences (read: found the financial incentive to research & publish all the information needed) to distinguish Chihuahua DNA from Great Dane DNA.
This is entirely different, however from comparing DNA from the saliva in a dog bite to DNA from a suspected assailant - that should be doable, but whether your local forensics lab is willing to contribute the labor & supplies necessary to do so is a different matter.
Sue from El Paso
Experience is what you get when you didn’t get what you wanted.
Sue, you are my favorite Doctor. You put that in english any NY cab driver could understand.
The “Do dogs have DNA” question has been milling about in my brain since I read an article in the Smithsonian about a year ago about the newest breed of dog discovered and named, I think, the North Carolina dog, in the state of that name in the 1990’s. The guy who noticed the mongrels from state to state seemed to have the same look to them, found a pack of similar looking dogs in NC and studied them. Somehow he managed to domesticate the pack and discovered that this breed of dog was older than most other domestic breeds in the world. It was related or descended from ( I can’t remember) the wolf.
The only reason I remember this stuff is when the scientist who did the stuff with the DNA or blood work ( don’t you love how technical I am?) realized that the mutt North Carolina dog is related to the wolf, he realized the tonnage of importance that meant and said,
“Wow.” and went off to have a beer.
“It was related or descended from ( I can’t remember) the
wolf.”
No mystery there. My friend has a pack of them, half wolves. Nasty attitude looking things, but quite exotic.
Dogs and wolves are the same species. We pretend they aren’t, because historically there’s been a distinction made between canis familiaris and canis lupus, but they don’t really meet the criteria for seperate species (they can, and sometimes do, freely interbreed and the offspring are fertile).
In a related story, I seem to recall that a man was placed at the scene of a crime by matching the DNA fingerprint of a cat hair on his clothes to a cat the victim had in her apartment. Or something like that.
IIRC, it was the first time someone was convicted using non-human DNA evidence.
If I wanted smoke blown up my ass, I’d be at home with a pack of cigarettes and a short length of hose.
1-800-dna-type will (perhaps) connect you to a lab that will DNA type anything you want.
They don’t mess with the essentials of “chain of something” needed for court work but if you wanted to know if two samples matched they would do it. $300-$500.
I recently put down a large chunk of change for an adorable pure-bred dog. One of the things the AKC, and others who seem to know what they are talking about, recomended is a genetic test of the parents to determine if they have the marker gene for many different diseases or abnormalities. At the breeders I was shown a certificate that the parents were free of any genetically inherited eye or hip problems.
Kudos to Alphagene - I usually watch shows such as the New Detectives, which dramatize murder cases and how they are solved with the help of forensic sciences. I believe they did that one about the cat, also there was another case where they linked the suspect to the scene of the crime by doing a DNA test on some seed pods from nearby trees. A few of these pods were found in the suspects pickup, they actually matched them to the specific tree, as far as the show claimed, that was probably the first time that was ever done.
I wish I could find the reference, but I remember a story about cattle rustlers being busted because the calf they stole was compared to an uncooked steak from the mother and found to be a match.
A really interesting thing about DNA testing dogs is that the realtionships between breeds can be worked out. It seems that almost 3/4 of all domestic dogs today can trace their ancestry back to a single female dog. Interesting stuff. More complete info can be found at this website http://www.kc.net/~wolf2dog/dnaid.htm
Pretty interesting stuff.
I too became interested after laying out a chunk of cash for an unusual breed of dog (German Pinscher).
Just a quick question. I know that DNA exists in strings and very tiny strings at that. I also know that it is possible for theses “strings” to be damaged, and therefore unusable. So wouldn’t the process of winemaking, or the freezing of a steak do this? How could you use that DNA in a comparison? Sorry, I’m pretty ignorant in the field of biology.
“Teaching without words and work without doing are understood by very few.”
-Tao Te Ching
Democritus, You’d certainly think so, but from what I read DNA is pretty tough. I think they can grind up prehistoric teeth or whatever is in teeth (yikes) and get DNA from that. Wine and steaks just haven’t been damaged enough. And think about the cat hair story above…
The short answer is that the process of matching DNA works as well on fragments of DNA as it does on whole chromosomal-length DNA. In fact, very long segments of DNA usually are fragmented by enzymes called restriction endonuclases before being analyzed.
nuclease = enzyme that breaks apart the DeoxyriboNucleotides (building blocks of DNA).
endonuclease = enzyme that breaks bonds between “inside” nucleotides (an exonuclease chews off the end nucleotide, one at a time)
restriction endonuclease = enzyme that only breaks bonds between nucleotides that occur in a certain sequence. Usually the occurs in a palindromic segment of DNA such as:
These enzymes, then, "restrict" their activity to such segments. 100-500 base pair length segments are easy to work with. Chromosome length pieces are damn all to work with. By using different endonucleases, though, you can make overlapping segments & figure out the whole sequence.
When the DNA is already in multiple pieces because of having been aroung a few million years or whatever, there are usually enough copies so that these pieces overlap, too.
The long answer is...well damn, I guess that was the long answer.
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Sue from El Paso
Experience is what you get when you didn't get what you wanted.