May 17, 2008

Complete mtDNA genomes of Bos taurus and Bos indicus

Cytogenet Genome Res. 2008;120(1-2):150-156. Epub 2008 Apr 30.

Complete mitochondrial genomes of Bos taurus and Bos indicus provide new insights into intra-species variation, taxonomy and domestication.

Hiendleder S, Lewalski H, Janke A.

The taurine and zebuine cattle breeds comprise the majority of the world cattle population but their taxonomic status is still controversial. The two forms of cattle are currently classified as Bos taurus and Bos indicus species and are differentiated primarily by the presence or absence of a hump. However, these two species hybridize readily, producing fully fertile offspring. We have determined and analyzed complete B. taurus and B. indicus mitochondrial genome sequences to investigate the extent of sequence divergences and to study their taxonomic status by molecular dating. The sequences encompassed 16,338 and 16,339 nucleotides, respectively, and differed at 237 positions. Estimated divergence times indicated that the two cattle lineages separated 1.7-2.0 million years ago. Combined phylogenetic analyses of 18 new and 130 previously reported extant B. taurus and B. indicus control region sequences with data from 32 archaeological specimens of the extinct wild aurochs (Bos primigenius) identified four major maternal lineages. B. primigenius haplotypes were present in all but the B. indicus lineage, and one B. taurus sequence clustered with B. primigenius P haplotypes that were not previously linked with domestic cattle. The B. indicus cluster and a recently reported new B. primigenius haplotype that represents a new lineage were approximately equidistant from the B. taurus cluster. These data suggest domestications from several differentiated populations of B. primigenius and a subspecies status for taurine (B. primigenius taurus) and zebuine (B. primigenius indicus) cattle.



miz RAND BLOWTON said...

Yummy Yum Yum-which cow makes the best Beef Stew and which makes the most balanced milk? I'm sure scientists know the answer to that!

(The skinny Indian one looks good in high-heel shoes and a mini skirt)-except for that big thing on their neck-just joking!

miz RAND BLOWTON said...

Seriously..I know the Zebu Indicus can tolerate heat and bugs,more than western cattle-so those traits are incorporated into some of the western cows-I still can't tell by looking at it, if it's a beef or milk cow?????
DNA is present in plants,animals,as well as man so they can all be studied.I like reading about the cows as much as I like reading about people.

terryt said...

Miz. Beef from Wagyu, a breed of basically Japanese origin, is usually considered the best. Marbled fleh, i.e. fat distributed through it. However Wagyus are very slow maturing. Amoung European breeds angus, of Scottish origin, is usually regarded as especially good quality although Murray grey, a breed derived from angus hybrids, also wins a few prizes for tasty beef.

Milk is harder to judge because it depends what you mean by ballanced. More fat? less fat? more protein? etc. Quantity is dominated hy Holsteins, originally a Dutch breed.

Interesting snippets from the post: "these two species hybridize readily, producing fully fertile offspring". And: "the two cattle lineages separated 1.7-2.0 million years ago". Now modern humans and Neanderthals separated a mere half million years ago but many people believe the two species were unable to produce fertile hybrids. I realise speciation is not simply a function of time but something strange is going on here.