愛爾蘭科學家５日發(fā)表報告稱,，基因分析證實，全世界現(xiàn)有５０多萬匹純種賽馬都是生活在１８到１９世紀的２８匹馬的后代,。
１８世紀,，英國人最早開始培育純種馬。他們用英國母馬和馳騁在阿拉伯半島的駿馬交配,，培育出特別適合長距離賽跑的馬匹,。如今，純種馬是世界上最名貴的馬匹,，由其而生的賽馬業(yè)每年產(chǎn)值超過幾十億美元,。
為了考察現(xiàn)代賽馬的基因多樣性，愛爾蘭都柏林三一學院的科學家對２２１匹純種馬和１１７匹埃及馬,、土耳其馬的ＤＮＡ（脫氧核糖核酸）微衛(wèi)星進行了比較,。ＤＮＡ微衛(wèi)星是指ＤＮＡ基因組中小于１０個核苷酸的簡單重復序列，又稱短串聯(lián)重復,。
分析結(jié)果表明,，全世界現(xiàn)有的５０多萬匹純種馬都是生活在兩、三百年前的２８匹馬的后代,。更讓人驚訝的是,，９５％的雄性賽馬的Ｙ染色體來自１７００年出生的一匹阿拉伯駿馬。
這種遺傳學篩選方法同樣適用于人類的進化和遷徙的研究,，是經(jīng)典的遺傳學研究方法,。
以下是英文原文：
Virtually all 500,000 of the world’s thoroughbred racehorses are descended from 28 ancestors, born in the 18th and 19th centuries, according to a new genetic study. And up to 95% of male thoroughbreds can be traced back to just one stallion.
Thoroughbred horses were developed in 18th century in the UK. English mares were bred with Arabian and other stallions to create horses with great stamina for distance racing. Today, thoroughbreds are the most valuable of breeds, representing a multi-billion dollar annual industry, worldwide.
To assess the genetic diversity of modern racing horses, geneticist Patrick Cunningham of Trinity College in Dublin, Ireland, compared 13 microsatellite DNA loci – repeating sequences of DNA which vary in length – in 211 thoroughbreds and 117 other Shetland, Egyptian and Turkish horses. He also examined studbooks dating back to 1791.
He found the majority of the half million progeny alive today are descended from just 28 “founder” horses.
It was already known that just a handful of stallions (but many mares) were used to found the thoroughbred breed. But startlingly, the new research finds that, in 95% of modern racehorses, the Y-chromosome can be traced back to a single stallion - the Darley Arabian, born in 1700.
Speedy selections
Related work on sequencing the horse genome is also uncovering genes in thoroughbreds linked to speed and stamina. Screening for these traits could one day guide owners' and breeders' decisions when buying horses, which may sell for many millions of dollars.
"We hope to produce sounder, faster and better-performing horses," says Cunningham. He and colleague Emmeline Hill at University College Dublin is also using the horse genome to uncover genes that explain why one animal runs faster than another.
"Horses are flight animals naturally selected for speed and stamina in the wild," explains Hill. "With domestic selection, speed was further augmented in the thoroughbred."
Thirty-five per cent of the difference in racing performance between horses can be explained by genetics alone, says Hill. She is cross-referencing up to 140 recently discovered human genes for fitness and performance in a bid to track down equine equivalents. These genes are involved in traits related to the cardio-respiratory system, muscle strength and metabolism, she says.
Bleeding lungs
However, the analysis of thoroughbred genetics is also revealing the other side of the coin, notes Matthew Binns of the Royal Veterinary College in London, UK. Many negative traits are associated with inbreeding in the diminutive gene pool, he says. "The selections we've made for fantastic beasts have had some detrimental consequences."
One tenth of thoroughbreds suffer orthopaedic problems and fractures, 10% have low fertility, 5% have abnormally small hearts and the majority suffer bleeding in the lungs, says Binns.
But as well as allowing breeders to select for performance-related genes, elucidating the horse genome may allow researchers to breed out negative traits, he says.
"Now we have a good amount of the horse genome, there are interesting times ahead," says Binns. "Over the next 10 years there will be some changes in this very traditional industry."
Cunningham presented his findings on Monday at the British Association Festival of Science in Dublin.
