The History Channel had a good program on last night about genealogy of the Royal Family. According to the genetic evidence, Queen Elizabeth's hemophilia gene was a spontaneous mutation which she had from birth and which neither of her parents had (it is now accepted that QE was not an illigitimate child).
OOOOPPPPPS!!!! I meant Queen Victoria, not Queen Elizabeth! Grandmother, I believe, of the son of the last Czar of Russia (son of Czar Nicholas II was a hemophiliac who inherited the gene from Queen Victoria of England).
It has been proposed that the mutation occurred in Victorias fathers testis. Older men tend to father more mutants than young men, but we really do not know if the mutation occurred in her mother or father.
It's not important (unless we're going to write a paper) but the chemists I hang around with attribute the molecular clock to Pauling. Here is the abstract of a 1998 review article, which I can't read because it is written in Japanese. The authors attribute the molecular clock to Pauling, at least as I read the abstract they do. But, frankly, I haven't seen the original literature, Here is the abstract:
I've read the Zuckerkandl and Pauling paper and it is not about the molecular clock. It was a theory paper in which they suggested that the molecules could be used to determine evolutionary relationships. It must be a bad translation of Japanese. At the time that the paper was written there wasn't enough data to infer a clock. I don't think that Kimura had come up with the neutral theory yet. They also made the blunder that I mentioned before in that paper. I'll look up the reference because you won't find it in PubMed because it dates before 1981. I think it dates from the 1960's, but I read the paper in the early 80's so I could just be remembering wrong.
I was wondering if all genetic hemophiliacs have a genetic link with Queen Elizabeth or if the random mutation occurs often enough that the hemophiliacs living today are mostly unrelated to each other (i.e. they trace their hemophilia gene to ancestors that they don't have in common).
I don't know how many hemophiliacs have died of AIDS, but in the late 1980s the companies making the clotting factor were using blood products that contained HIV. A (hemophiliac) friend of mine died of AIDS about 6 years ago.
What does this have to do with poultry genetics? Well, it addresses the rate of random mutation which is relevant to poultry genetics. I would really like to find the Red-Splashed White gene and keep a line of Red-Splashed White Rhode Island Red chickens. Rokimoto had a good idea to try to introduce the Exchequer-type mottling gene into the RIRs.
The basis for Linus Pauling's "molecular clock" is the idea that random mutations in DNA occur at a constant rate, when viewed over a long time span. But, what the basic rate is (mutations per thousand years) in a genome, I don't know.
By Infomaniac on Thursday, January 24, 2002 - 03:28 pm:
By Rokimoto on Thursday, January 24, 2002 - 06:02 pm:
Genes are big and many different mutations in the same gene can have similar effects. Duchenes muscular dystrophy is a very common mutation in humans. The gene is a million base-pairs long and many mutations are deletions within this long gene.
Achondroplastic dwarfism is one of the most common mutations in humans. It occurs in about 1 in 10,000 live births. Since it is a dominant mutation we can easily calculate that it's mutation rate is around 10^-4. Most genes mutate at a rate at least 100 times less frequently. Mutations that have observable effects in genes are literally one in a million. This is why we do not often see new mutations in our flocks.
All the domestic hamsters in the world are derived from a single litter. All the mutants that you see in the pet store have occurred in the domestic hamster population since the mid 1900's.
I don't think that Linus Pauling came up with the Molecular clock idea. Pauling and his associate Zuckerkandle? came up with the idea that we could trace the evolutionary history of an organism by looking at it's genetic material and observing the differences between species. The thing is that they were kind of right, but their thinking was wrong. They thought that they could sequence the proteins of a lamprey, fish and frog and get "fossil" sequences that would tell them evolutionary relationships. They forgot to think about the fact that the present lamprey have been evolving for as long as every other species on the planet. They could have realized that they would be observing molecular evolution in both branches lamprey and fish and lamprey and frogs, but they were assuming that the frogs changed and the lamprey had stayed the same.
This just makes it more difficult to analyze the data, but we have computers, now and I have two program suites that we use that can analyze the sequence of 10 taxa in a matter of minutes on my desk top computer. 10 years ago we worked on dedicated high speed workstations and it took much longer to analyze 5 taxa. Because of the method of calculation adding taxa does not increase the time linearly, but each new taxa adds more and more time until you could be waiting for days to see your results.
The molecular clock was an inference made after people got a lot of data and it began to look like mutations accumulated at a constant rate between very divergent species from man to bacteria. Wilson's lab was a major proponent of the molecular clock. It is a pretty inaccurate clock, but if you don't mind being off by a couple of million years out of 10 it is OK.
By Infomaniac on Thursday, January 24, 2002 - 07:00 pm:
1998:81209 CAPLUS
DN 128:124872
TI Molecular clock measuring biological evolution
AU Miyata, Takashi; Nikoh, Naruo
CS Grad. Sch. Sci., Kyoto Univ., Kyoto, 606-01, Japan
SO Kagaku (Tokyo) (1998), 68(2), 195-201
CODEN: KAGTAT; ISSN: 0022-7625
PB Iwanami Shoten
DT Journal; General Review
LA Japanese
CC 6-0 (General Biochemistry)
Section cross-reference(s): 3, 12, 13
AB A review with 12 refs., on the relationship between mutations in DNA and
evolution, the "mol. clock" discovered by Zuckerkandl and Pauling, dates
of the divergence between humans and the apes, and origin and evolution of
modern humans estd. by anal. of mitochondrial DNA of humans and
Neanderthals. Explosive evolution of animals (Cambrian explosion) are
also discussed by means of mol. clocks.
ST review mol clock evolution human primate; animal evolution mol clock DNA
review
IT Animal
Molecular evolution
Primate
(mol. clock measuring evolution in animals)
IT DNA
RL: BSU (Biological study, unclassified); BIOL (Biological study)
(mol. clock measuring evolution in animals)
By Rokimoto on Friday, January 25, 2002 - 12:04 am: