The BBC wildlife magazine for April 2013 had an article entitled 'How to recreate extinct species'. Here is the article in full (all credits go to BBC wildlife magazine and Henry Nichols (author of the article)).
Can we resurrect extinct species?
I recently read about a project to bring back the extinct aurochs, and a couple of years ago scientists claimed to be trying to clone a mammoth. How can we bring back extinct species-and should we?
when Micheal Critchton's novel 'Jurassic park' was published in 1990, The prospect of bringing extinct species back to life was little more than brilliant fiction. But, with recent advances in genetics, This is no longer the case.
There are two approaches to resurrection. Cloning involves inserting DNA into an egg cell from a similar living species,which is then implanted into a female to bring to term. Breeding back,by contrast,involves taking extant descendants of now-extinct species and selectively breeding them to recreate something more like their long-lost forebears.
when it comes to cloning , there are two essential ingredients: High quality ,complete DNA and the means to grow a cloned embryo to adulthood. Because DNA degrades rapidly, there is little chance of bringing back species that died out more than 100,000 years ago. So dinosaurs are out. But for more recently extinct species, where there are well-preserved specimens that still contain DNA and a suitable surrogate species, resurrection is a theoretical possibility.
Long live the mammoth?
The wooly mammoth appears to be the perfect candidate. Every specimen exhumed from the Siberian permafrost sparks a frenzy of speculation that one of its cells might contain a perfectly preserved nucleus (which stores the genetic information). Once thawed, this could replace the nucleus from an egg from the mammoth's closest relative, the Indian elephant. Cell division would be stimulated with chemicals or an electric current, and the resulting embryo inserted into a female elephant to bring them to term.
Alternatively , if the frozen mammoth were a male and its testes still contained viable sperm,these could be used to fertilize an elephant egg,creating a hybrid. However, the odds of pulling intact cells or sperm from ice are vanishing small- All mammoth DNA recovered to date has came in jumbled fragments rather than seamless stretches. Despite this,efforts continue. In 2008,researchers rearranged these snippets into a draft sequence of the mammoth genome. Though this is just a string of letters on a computer screen, there are at least two ways it could be transformed into a living, breathing mammoth. The purist's method would be to synthesise a nucleus from stratch, then clone it into an elephant egg. But at present constructing such vast lengths of DNA in a lab,let alone fashioning them into a fully functional nucleus, is just not possible. The alternative-a quick-and-dirty approach to mammoth making- would be to engineer an elephant embryo with mammoth like qualities,such as domed head and a shaggy coat of ginger hair. But it's not quite as simple as that. Even with a fully functional nucleus,cloning requires an abundant supply of suitable eggs.
part two soon
