Download F94L – A Muscling Mutation in Limousin Cattle

Animal Genetics Laboratory
SCHOOL OF VETERINARY SCIENCE
Gatton, QLD 4343
F94L – A Muscling Mutation in Limousin Cattle
The Animal Genetics Laboratory offers testing to Limousin breeders for the F94L muscling mutation. This
test is performed on a quarterly basis (January, April, July, October) for those breeders wishing to test their
animals. Application forms are available from the Australian Limousin Breeders’ Society.
What is the F94L Mutation?
The F94L mutation is located in the growth differentiation factor-8 gene, commonly called the myostatin
gene. Research conducted at The University of Adelaide showed that some Limousin animals carried a
mutation in the myostatin gene which caused increased carcass weight, silverside percentage and eye
muscle area1. The F94L mutation does not cause the extreme double-muscling that other mutations in the
myostatin gene cause in breeds such as Belgian Blue.
The mutation in the myostatin gene is a type of mutation called a ‘point mutation’ or a ‘single nucleotide
polymorphism’ (SNP). It is where one single letter in the genetic code gets changed to a different letter. In
the case of the F94L mutation, a ‘C’ has been changed to an ‘A’. The change in the genetic code is a natural
process that sometimes spontaneously takes place during cell replication. When this takes place in the
gametes (eggs or sperm) the mutation is passed onto the progeny and forms their unchanging genetic
make-up.
The F94L mutation is so named because the C → A mutation causes a change in the protein sequence at
amino acid position 94. (Amino acids are the building blocks of proteins and are each coded by three
letters of the genetic code.) The C → A mutation causes a change from phenylalanine to leucine at position
94, thus, F94L.
Animals carry two copies of every gene. Research has shown that the effect of the F94L mutation is greater
in animals that carry two copies of the ‘A’ allele (homozygous-A animals) than in animals that carry one
copy of the ‘A’ and one copy of the ‘C’ (heterozygous animals) and animals that have two copies of the ‘C’
allele (homozygous-C animals).
The F94L mutation has been shown to exist in Limousin, Charolais, Blonde d’Aquitaine and Angus cattle 2,3.
However, it is present at a high frequency in Limousin cattle (83-94%)3,4 and is present at a particularly high
frequency in the French Pure Limousin lines (98.9%)4.
Sellick, G.S., et al. (2007) Effect of myostatin F94L on carcass yield in cattle. Animal Genetics; 38: 440-446.
Dunner, S., et al. (2003) Haplotype diversity of the myostatin gene among beef cattle breeds. Genetics Selection Evolution; 35: 103-18
th
3 Sellick, G.S., et al. (2006) Polymorphisms within the cattle myostatin gene. Proceedings of the 30 International Congress of Animal Genetics; 30: A494
Vankan,
D.M.,
et
al.
(2010)
Real-time
PCR
genotyping
and
frequency
of
the
myostatin
F94L
mutation
in beef cattle breeds. Animal; 4: 530-534
4
1
2
How do we test for the F94L Mutation?
A common method for detecting single nucleotide polymorphisms (SNP) is to ‘cut’ the DNA with a
restriction enzyme. Restriction enzymes are proteins that cut DNA at a specific point in a specific sequence.
The restriction enzyme used in the F94L test is called TaqI and is a protein isolated from bacteria.
TaqI will cut a DNA sequence containing the letters or ‘bases’ T-C-G-A. This sequence of bases is located in
the myostatin gene where the F94L mutation occurs. Animals that carry the ‘C’ allele of the F94L mutation
will have their DNA cut by TaqI. However, animals that carry the preferred ‘A’ allele of the F94L mutation
will not have their DNA cut by TaqI.
Therefore, the presence of the ‘C’ allele will result in two fragments of DNA (of 100 base pairs and 110 base
pairs in length) whereas the presence of the ‘A’ allele will not be cut by TaqI and result in one fragment (of
210 base pairs in length). Animals that are heterozygous for F94L (carry both an ‘A’ and a ‘C’) will have all
three fragments of DNA (100, 110 and 210 base pairs in length).
F94L Factsheet, final version
P:\DOC\FORMS\Fact Sheets\Word Documents, last modified 21 May 2013, final version